
	Exposure Research

NERL News

About NERL

Where You Live

Publications/
Presentations

Assistance
Opportunities

Ecosystems Research Division Publications: 2006

This page lists publication titles, citations and abstracts produced by NERL's Ecosystems Research Division for the year 2006, organized by Publication Type. Your search has returned 159 Matching Entries.

See also Ecosystems Research Division citations with abstracts: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008

Technical Information Manager: Janice Sims - (706) 355-8011 or sims.janice@epa.gov

		Presented/Published
EPA PUBLISHED PROCEEDINGS	Fish Physiology, Toxicology, and Water Quality:	06/29/2006

U.S. EPA. Fish Physiology, Toxicology, and Water Quality:. Proceedings of the Eighth International Symposium, Chongqing, CHINA, October 12 - 14, 2004. D.J. Randall and M. Dung Yuk Man (ed.), U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/062 (NTIS PB2006-114095), 2006.
Abstract:	Twenty-one participants from Europe, North America and China convened in Chongqing, China, October 12-14, 2005, for the Eighth International Symposium in Fish Physiology, Toxicology and Water Quality. The subject of the meeting was "Hypoxia in vertebrates: Comparisons of terrestrial and aquatic vertebrates". These Proceedings include 13 papers presented over the three day period and discuss the responses of fish, reptiles and mammals to hypoxia. These papers report on the responses of animals to hypoxia at the behavioural, physiological and molecular levels. Clearly hypoxia has wide ranging effects, the responses are complex and there are many similarities in the responses of all vertebrates to hypoxia. Organisms respond to hypoxia by reducing energy expenditure, in particular inhibiting reproduction, feeding and exercise. That is animals only expend energy that is absolutely necessary for survival. There is extensive reorganization of cellular machinery directed by hypoxia inducible factors (HIFs), proteins that increase during hypoxia and have a marked effect on the expression of many genes. As a result, anaerobic metabolism is up regulated and many aspects of aerobic metabolism are down regulated. Many cells enter cell cycle arrest. Thus organisms stop reproducing and growing during hypoxia and if the effects of hypoxia are severe, development of eggs and larvae is compromised.

JOURNAL	A Screening Model for Simulating Dnapl Flow and Transport in Porous Media: Theoretical Development	01/01/2006

WILLSON, C. S., J. W. WEAVER, AND R. J. CHARBENEAU. A Screening Model for Simulating Dnapl Flow and Transport in Porous Media: Theoretical Development. ENVIRONMENTAL MODELLING AND SOFTWARE. Elsevier Science Ltd, London, Uk, 21(1):16-32, (2006).
Abstract:	There exists a need for a simple tool that will allow us to analyze a DNAPL contamination scenario from free-product release to transport of soluble constituents to downgradient receptor wells. The objective of this manuscript is to present the conceptual model and formulate the equations and modules which are utilized in this screening model.

JOURNAL	Estimating Streamflow and Associated Hydraulic Geometry, the Mid-Atlantic Region, USA	06/15/2006

MOHAMOUD, Y. M. AND R. S. PARMAR. Estimating Streamflow and Associated Hydraulic Geometry, the Mid-Atlantic Region, USA. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION. American Water Resources Association, Middleburg, VA, 42(3):755-768, (2006).
Abstract:	Methods to estimate streamflow and channel hydraulic geometry were developed for ungaged streams in the Mid-Atlantic Region. Observed mean annual streamflow and associated hydraulic geometry data from 75 gaging stations located in the Appalachian Plateau, the Ridge and Valley, and the Piedmont Physiographic Provinces of the Mid-Atlantic Region were used to develop a set of power functions that relate streamflow to drainage area and hydraulic geometry to streamflow.

JOURNAL	Probing the Enantioselectivity of Chiral Pesticides	01/02/2006

GARRISON, A. W. Probing the Enantioselectivity of Chiral Pesticides. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(1):16-23, (2006).
Abstract:	Up to 25% of all pesticides are chiral; that is, they exist as two mirror image isomers called enantiomers. It is known that enantiomers usually differ in their biological properties through their differential interaction with enzymes or other naturally occurring chiral molecules. This may lead to differences in microbial degradation rates, which would mean that one enantiomer is more persistent in the environment than the other. Comprehensive risk assessments require a combination of exposure data with effects factors; therefore, it is desirable to assess enantiomer selectivity for both exposure and effects.

JOURNAL	Identification and Prediction of Fish Assemblages in Streams of the Mid-Atlantic Highlands, USA	02/01/2006

CYTERSKI, M. J. AND M. C. BARBER. Identification and Prediction of Fish Assemblages in Streams of the Mid-Atlantic Highlands, USA. TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY. American Fisheries Society, Bethesda, MD, 135(1):40-48, (2006).
Abstract:	Managing aquatic resources requires meaningful assessment endpoints on which to base decisions. In freshwater streams, assessment endpoints are often defined as fish communities. Given limited resources available for environmental monitoring, having a means of predicting fish assemblages in streams where no sampling has yet occurred would be useful. This tool could be used for regional screening-level analyses of fish communities, as well as input to local scale model applications for evaluating management scenarios of stream degradation/restoration. In this study a set of fish assemblages (a list of fish species and their corresponding relative abundances) representative of different stream types in the Mid-Atlantic Highlands (MAH) region of the United States was defined using a k-means cluster analysis performed on relative abundance estimates.

JOURNAL	A Simple and Fast Extraction Method for Organochlorine Pesticides and Polychlorinated Biphenyls in Small Volumes of Avian Serum	02/06/2006

SUNDBERG, S. E., J. J. ELLINGTON, AND J. J. EVANS. A Simple and Fast Extraction Method for Organochlorine Pesticides and Polychlorinated Biphenyls in Small Volumes of Avian Serum. JOURNAL OF CHROMATOGRAPHY: B BIOMEDICAL SCIENCES AND APPLICATIONS. Elsevier Science Ltd, New York, NY, 831(1-2):99-104, (2006).
Abstract:	A solid-phase extraction (SPE) method was developed using 8 M urea to desorb and extract organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) from avian serum for analysis by capillary gas chromatography with electron capture detection (GC-ECD). The analytes were efficiently extracted from the denatured serum- lipoprotein-analyte complex by one passage through an Oasis® HLB (hydrophilic- lipophilic-balanced) SPE cartridge. No further cleanup was necessary, the entire extraction procedure and GC-ECD analysis can be accomplished in less than three hours. Serum volumes ranged from 100 µL to 1 mL with absolute recoveries of 90-101% for PCBs and 74% to 101% for the OC pesticides.

JOURNAL	Modulation of the Cytotoxicity and Genotoxicity of the Drinking Water Dbp Iodoacetic Acid By Suppressors of Oxidative Stress	03/31/2006

CEMELI, E., E. D. WAGNER, D. ANDERSON, S. D. RICHARDSON, AND M. J. PLEWA. Modulation of the Cytotoxicity and Genotoxicity of the Drinking Water Dbp Iodoacetic Acid By Suppressors of Oxidative Stress. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(6):1878-1883, (2006).
Abstract:	Drinking water disinfection by-products (DBPs) are generated by the chemical disinfection of water and may pose a hazard to the public health. Previously we demonstrated that iodoacetic acid was the most cytotoxic and genotoxic DBP analyzed in a mammalian cell system. Little is known of the mechanisms of its genotoxicity. The involvement of oxidative stress in the toxicity of iodoacetic acid was analyzed with the antioxidants catalase and butylated hydroxyanisole (BHA). Iodoacetic acid toxicity was quantitatively measured with and without antioxidants in Salmonella typhimurium strain TA100 and with Chinese hamster ovary (CHO) cells. The endpoints included cytotoxicity in S. typhimurium or in CHO cells, mutagenicity in S. typhimurium, and genotoxicity in CHO cells. Neither catalase nor BHA reduced the level of iodoacetic acid-induced cytotoxicity in S. typhimurium. In CHO cells neither antioxidant caused a significant reduction in iodoacetic acid-induced cytotoxicity. However, in S. typhimurium, BHA or catalase reduced the mutagenicity of iodoacetic acid by 33.5% and 26.8%, respectively. Likewise, BHA or catalase reduced iodoacetic acid-induced genomic DNA damage by 86.5% and 42%, respectively. These results support the hypothesis that oxidative stress is involved in the induction of genotoxicity and mutagenicity by iodoacetic acid.

JOURNAL	Estrogenic Activity of Dicofol With the Human Estrogen Receptor: Isomer-and Enantiomer-Specific Implications	06/15/2006

HOEKSTRA, P. F., B. K. BURNISON, A. W. GARRISON, T. NEHELI, AND D. C. MUIR. Estrogenic Activity of Dicofol With the Human Estrogen Receptor: Isomer-and Enantiomer-Specific Implications. CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 64(1):174-177, (2006).
Abstract:	Dicofol is a non-systemic acaricide/miticide currently registered in the U.S. and Canada for use on a wide variety of crops. This agrochemical has been identified as a potential candidate substance for the United Nations Economic Commission for Europe (UN-ECE) Persistent Organic Pollutant (POP) Protocol and implicated as a potential endocrine disrupting compound. The technical product is usually synthesized from technical DDT and consists of approximately 80 percent and 20 percent of p,p´- and o,p´-dicofol isomers. The o,p´-substituted isomer of dicofol is chiral and may have enantiomer-specific activity; however, the stereospecific activity of o,p´-dicofol has not been reported. In this study, we examined the isomer- and enantiomer-specific endocrine disruption potential of dicofol using yeast-based steroid hormone receptor gene transcription assay designed with the human estrogen receptor (hER). Estrogenic activity of (plus)-17-beta estradiol (positive control), p,p´-dicofol, racemic o,p´-dicofol [(plus minus)-o,p´-dicofol] and the individual o,p´-dicofol enantiomers was measured via quantification of beta-galactosidase. The (plus minus)-o,p´- and p,p´-dicofol were weak estrogen mimics (EC50: 4.2 × 10(-6) M and 1.6 × 10(-6) M, respectively) relative to estradiol (3.7 × 10(-10) M). For o,p´-dicofol, the beta-galactosidase induction by (-)-o,p´-dicofol (EC50: 5.1 × 10(-7) M) was greater than the racemic mixture. However, the (+)-o,p´-dicofol enantiomer was found to have negligible estrogenic activity. These data indicate that dicofol is a weak hER agonist due to activity of the achiral p,p´-isomer and (-)-o,p´-substituted enantiomer and emphasizes the influence of chemical structure and configuration on biological responses to exposure from chiral compounds.

JOURNAL	Estimation of Phosphate Ester Hydrolysis Rate Constants. I. Alkaline Hydrolysis	02/20/2006

WHITESIDE, T. S., S. H. HILAL, AND L. A. CARREIRA. Estimation of Phosphate Ester Hydrolysis Rate Constants. I. Alkaline Hydrolysis. QSAR & COMBINATORIAL SCIENCE. John Wiley & Sons, Ltd., Indianapolis, IN, 25(2):123-133, (2006).
Abstract:	SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition states of a molecule. This difference is a function of the reference rate and internal and external perturbations to the reference rate. The internal perturbations are comprised of electrostatic and resonance effects. The external perturbations quantify solute-solvent interactions based on the dielectric constant of the solvent and the steric effect of substituent groups. These perturbation models have been tested using 225 reliably measured second order hydrolysis rate constants over a variety of temperatures. The RMS deviation of the calculated versus observed values was 0.401 log M-1 s-1.

JOURNAL	Groundwater N Speciation and Redox Control of Organic N Mineralization By O2 Reduction to H2o2	07/15/2006

WASHINGTON, J. W., R. THOMAS, D. M. ENDALE, K. L. SCHROER, AND L. SAMARKINA. Groundwater N Speciation and Redox Control of Organic N Mineralization By O2 Reduction to H2o2. GEOCHIMICA ET COSMOCHIMICA ACTA. Elsevier Science Ltd, New York, NY, 70(14):3533-3548, (2006).
Abstract:	Samples were collected from one spring and one well that were selected to reflect agricultural impacts, and a spring and a well that were considered to show little to no evidence of agricultural impact. These samples were characterized for fixed N species and dissolved organic N. These analytes were monitored in the agricultural spring for up to two years along with other analytes that we reported upon previously.

JOURNAL	Metabolomic Evaluation of Rat Liver and Testis to Characterize the Toxicity of Triazole Fungicides	06/15/2006

EKMAN, D. R., H. C. KEUN, C. D. EADS, C. M. FURNISH, R. N. MURRELL, J. C. ROCKETT, AND D. J. DIX. Metabolomic Evaluation of Rat Liver and Testis to Characterize the Toxicity of Triazole Fungicides. Metabolomics. Plenum Press, New York, NY, 2(2):63-73, (2006).
Abstract:	The effects of two triazole fungicides, myclobutanil and triadimefon, on endogenous rat metabolite profiles in blood serum, liver, and testis was assessed using proton nuclear magnetic resonance (1H-NMR) spectroscopy. Adult male Sprague-Dawley rats were dosed daily by gavage for 14 days with myclobutanil or triadimefon, at two dose levels for each triazole. Following exposure, serum, liver, and testis were collected and processed for NMR analysis. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) of the resulting spectra were used to determine changes in metabolite profiles as a result of exposure. Using this approach, responses common to both triazoles were identified, as well as responses indicative of differences in the toxicity of these two compounds. Although changes were observed in serum metabolites following exposure, none were robust enough to be considered a biomarker of exposure/effect. A number of metabolic changes were, however, observed in the liver with both triazoles, particularly in metabolites related to the methionine cycle. The testes of myclobutanil-exposed animals displayed altered levels of creatine and creatinine, consistent with testicular toxicity. Overall, the results of this study support the possible application of a metabolomics approach to assessing the toxicity of triazole fungicides and identifying biomarkers of exposure and/or effect.

JOURNAL	The Movement of Oil Under Non-Breaking Waves	09/15/2006

BOUFADEL, M. C., R. D. BECHTEL, AND J. W. WEAVER. The Movement of Oil Under Non-Breaking Waves. MARINE POLLUTION BULLETIN. Elsevier Science Ltd, New York, NY, 52(9):1056-1065, (2006).
Abstract:	The combined effects of wave kinematics, turbulent diffusion, and buoyancy on the transport of oil droplets at sea were investigated in this work using random walk techniques in a Monte Carlo framework. Six hundred oil particles were placed at the water surface and tracked for 500 wave periods. A dimensionless formulation was presented that allowed reporting distances in terms of the wave length and times in terms of the wave period. Stokes' drift was, expectedly, the major mechanism for horizontal transport. It was also found that plumes that have large terminal rise velocities move faster forward but spread less than those that have small terminal rise velocities. The increase in wave slope (or wave steepness) caused an increase in transport and spreading of the plume. Our results supported treating the oil as completely mixed vertically in a layer near the surface. In the horizontal direction, buoyant plumes had spreading coefficients that are essentially constant after about 200 wave periods. But neutrally buoyant plumes had horizontal spreading coefficients that increased with time (for the simulation time of 500 wave periods). Techniques for generalizing the results for a wide range of wave parameters were presented.

JOURNAL	Bioaccumulation, Biotransformation, and Metabolite Formation of Fipronil and Chiral Legacy Pesticides in Rainbow Trout	04/01/2006

KONWICK, B. J., A. W. GARRISON, M. C. BLACK, J. K. AVANTS, AND A. T. FISK. Bioaccumulation, Biotransformation, and Metabolite Formation of Fipronil and Chiral Legacy Pesticides in Rainbow Trout. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(9):2930-2936, (2006).
Abstract:	To assess the fate of current-use pesticides it is important to understand their bioaccumulation and biotransformation by aquatic biota. We examined the dietary accumulation and enantioselective biotransformation of the chiral current-use pesticide fipronil, along with a mixture of selected chiral [alpha-hexachlorocyclohexane (alpha-HCH), heptachlor epoxide (HEPX), polychlorinated biphenyls (PCBs) 84, 132, 174, o,p'-DDT, and o,p'-DDD], and non-chiral (p,p'-DDT, p,p'-DDD) organochlorine compounds in juvenile rainbow trout (Oncorhynchus mykiss). Fish rapidly accumulated all compounds, as measured in the carcass (whole body minus liver and GI tract) during the 32 d uptake phase, which was followed by varying elimination rates of the chemicals during the 96 d depuration period. No biotransformation was observed for alpha-HCH, HEPX, PCB 174, o,p'-DDT, or o,p'-DDD based on consistent enantiomeric fractions (EFs) in the fish and their t(1/2)s falling on a log Kow - log t(1/2) relationship established for recalcitrant contaminants in fish. p,p'-DDT and PCBs 84 and 132 were biotransformed based on the former's t(1/2) position below the log Kow - log t(1/2) relationship and the PCBs change in EF. Fipronil was rapidly biotransformed, based on a change in EF, a t(1/2) which fell below the log Kow - log t(1/2) relationship, which accounted for 88% of its elimination, and the rapid formation of fipronil sulfone, a known metabolite. Fipronil sulfone was found to persist longer than its parent compound fipronil and needs to be considered in fate studies of fipronil. This research demonstrates the utilities of the log Kow - log t(1/2) relationship as a mechanistic tool for quantifying biotransformation and of chiral analysis to measure biotransformation in fish.

JOURNAL	Multisubstrate Biodegradation Kinetics for Binary and Complex Mixtures of Polycyclic Aromatic Hydrocarbons	07/15/2006

KNIGHTES, C. D. AND C. A. PETERS. Multisubstrate Biodegradation Kinetics for Binary and Complex Mixtures of Polycyclic Aromatic Hydrocarbons. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 25(7):1746-1756, (2006).
Abstract:	Biodegradation kinetics were studied for binary and complex mixtures of nine polycyclic aromatic hydrocarbons (PAHs): naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, phenanthrene, anthracene, pyrene, fluorene and fluoranthene. Discrepancies between the observed biodegradation rates and those predicted by a sole-substrate model indicate that significant substrate interactions occurred in both the binary and complex mixture experiments. For all compounds except naphthalene, biodegradation was enhanced. The observations were compared to predictions from two multi-substrate biodegradation kinetic models: one that accounts for competitive inhibition and one that does not. Both models are fully predictive in that parameters had been determined from an independent set of sole-substrate experiments. In the binary experiments, the major multi-substrate effect was biomass enhancement due to growth on naphthalene. Substrate interactions were orders-of-magnitude larger for most of the compounds in the complex mixtures, but significant competitive inhibition effects counteracted some of the biomass enhancement effect. This study has demonstrated that the sole-substrate model is inadequate to describe multi-substrate biodegradation kinetics for a broad range of PAH mixtures. While the multi-substrate model without inhibition did an adequate job of predicting the observed effects in some cases, we advocate the use of the multi-substrate model with inhibition for similar modeling efforts in light of the evidence that the model was correct more often than not. Theory supports its use because of the common enzyme pathways for biodegradation of PAHs.

JOURNAL	Distribution of Chiral PCBs in Selected Tissues in the Laboratory Rat	06/15/2006

KANIA-KORWEL, I., A. W. GARRISON, J. K. AVANTS, K. C. HORNBUCKLE, L. W. ROBERTSON, W. W. SULKOWSKI, AND H. J. LEHMLER. Distribution of Chiral PCBs in Selected Tissues in the Laboratory Rat. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(12):3704-3710, (2006).
Abstract:	The enantiomeric enrichment of polychlorinated biphenyl (PCB) atropisomers has been reported in both wildlife and in humans. The biological processes causing this enrichment are only poorly investigated, a fact that limits the use of enantiomeric fractions (EFs) as a tool to study various processes of environmental relevance. To further understand these enantioselective processes, this study investigates the tissue distribution and EFs of some PCB atropisomers after administration of PCB mixtures to immature male Sprague-Dawley rats. The mixtures selected for this study, Aroclor 1254 and an environmental mixture extracted from Chlorofen-contaminated soil, are qualitatively different and are known to induce different groups of hepatic enzymes. Animals were sacrificed six days after dosing, PCBs were extracted, and, whenever possible, the EFs of PCBs 84, 91, 95, 149, 174 and 176 were determined by chiral gas chromatography. The EFs of PCB 95 (adipose tissue, liver and skin) and PCB 149 (adipose tissue, liver, skin and blood) in tissues from Aroclor 1254-treated animals differed significantly from EFs in the Aroclor standard, while only EFs of PCB 95 (blood) and PCB 174 (adipose tissue) in tissues from soil extract-treated animals were different from the Chlorofen soil extract. PCB 149 in tissues from soil extract-treated animals underwent no statistically significant enantiomeric enrichment. These differences in the EFs clearly suggest that the enantioselective enrichment of PCB atropisomers may correlate with exposure history, and with the induction of hepatic enzymes, and that EFs may be useful chemical markers of physiologic and biochemical changes following exposure to PCBs.

JOURNAL	Environmental Mass Spectrometry: Emerging Contaminants and Current Issues, 2006	06/15/2006

RICHARDSON, S. D. Environmental Mass Spectrometry: Emerging Contaminants and Current Issues, 2006. ANALYTICAL CHEMISTRY. American Chemical Society, Washington, DC, 78(12):4021-4046, (2006).
Abstract:	This biennial review covers developments in Environmental Mass Spectrometry over the period of 2004-2005. A few significant references that appeared between January and February 2006 are also included. Analytical Chemistry's current policy is to limit reviews to include 100-200 significant references and to mainly focus on new trends. As a result, as was done in the previous 2004 Environmental Mass Spectrometry review, this 2006 review will be limited in its focus to new, emerging contaminants and environmental issues that are driving most of the current research. Even with a more narrow focus, only a small fraction of the quality research publications could be discussed. Thus this review will not be comprehensive, but will highlight new areas and discuss representative papers in the areas of focus.

JOURNAL	Monitoring the Speciation of Aqueous Free Chlorine from Ph 1-12 With Raman Spectroscopy to Determine the Identity of the Potent Low-Ph Oxidant	07/01/2006

CHERNEY, D., S. E. DUIRK, J. C. TARR, AND T. W. COLLETTE. Monitoring the Speciation of Aqueous Free Chlorine from Ph 1-12 With Raman Spectroscopy to Determine the Identity of the Potent Low-Ph Oxidant. APPLIED SPECTROSCOPY. Society for Applied Spectroscopy, 60(7):764-772, (2006).
Abstract:	The speciation of aqueous free chlorine above pH 5 is a well-understood equilibrium of H2O + HOCl (equilibrium) OCl- + H3O+ with a pKa of 7.5. However, the identity of another very potent oxidant present at low pH (below 5) has been attributed by some researchers to Cl2 (aq), and by others to H2OCl+. We have conducted a series of experiments designed to ascertain which of these two species is correct. First, using Raman spectroscopy, we found that an equilibrium of H2O + H2OCl+ (equilibrium) HOCl + H3O+ is unlikely because the "apparent pKa" increases monotonically from 1.25 to 2.11 as the analytical concentration is increased from 6.6 to 26.2 mM. Second, we found that significantly reducing the chloride ion concentration changed the Raman spectrum and also dramatically reduced the oxidation potency of the low-pH solution (as compared to solutions at the same pH that contained equimolar concentrations of Cl- and HOCl). The chloride ion concentration was not expected to impact an equilibrium of H2O + H2OCl+ (equilibrium) HOCl + H3O+, if it existed. These observations supported the following equilibrium as pH is decreased: Cl2 (aq) + 2H2O (equilibrium) HOCl + Cl- + H3O+. The concentration-based equilibrium constant was estimated to be approximately 2.56 x 10(-4) M2 in solutions whose ionic strengths were ~0.01 M. The oxidative potency of the species in low pH solutions was investigated by monitoring the oxidation of secondary alcohols to ketones. These and other results reported here argue strongly that Cl2 (aq) is the correct form of the potent low-pH oxidant in aqueous free-chlorine solutions.

JOURNAL	Reduction of Nitrosobenzenes and N-Hydroxylanilines By Fe (II) Species: Elucidation of Reaction Mechanism	07/15/2006

COLON, D., E. J. WEBER, J. L. ANDERSON, P. WINGET, AND L. A. SUAREZ. Reduction of Nitrosobenzenes and N-Hydroxylanilines By Fe (II) Species: Elucidation of Reaction Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(14):4449-4454, (2006).
Abstract:	There has been a substantial effort toward understanding the reduction of nitroaromatics in Fe(II)-treated ferric oxide systems, little has been done to gain insight into the factors controlling the transformation of their reaction intermediates, nitrosobenzenes and N-hydroxylanilines, in such systems. Nitrosobenzenes, the first intermediates, were reduced by Fe(II) solutions as well as by Fe(II)-treated goethite suspensions at pH 6.6. Experimental observations indicate a reactivity trend in which the presence of electron-withdrawing groups in the para position increased the rate of reduction of the nitrosobenzenes. N-hydroxylanilines, the second intermediates, were reduced in Fe(II)-treated goethite suspensions but were not reduced by Fe(II)aq. Their reactivity trend indicates that electron-withdrawing groups in the para position decreased their rate of reduction. The bond dissociation enthalpy of the N-O linkage was the most useful molecular descriptor for predicting the rates of reduction of N-hydroxylanilines in Fe(II)-treated goethite suspensions suggesting that the breakage of the N-O bond is the rate-determining step for reduction. The rate of reduction of p-cyano-N-hydroxylaniline showed a linear relationship against the concentration of surface-associated Fe(II) in hematite, goethite, and lepidocrocite suspensions, while having a relatively low sensitivity toward changes in pH within the near-neutral range in hematite suspensions.

JOURNAL	QSAR Study of the Reduction of Nitroaromatics By Fe (II) Species	08/15/2006

COLON, D., E. J. WEBER, AND J. L. ANDERSON. QSAR Study of the Reduction of Nitroaromatics By Fe (II) Species. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(16):4976-4982, (2006).
Abstract:	The development of predictive models for the reductive transformation of nitroaromatics requires further clarification of the effect of environmentally relevant variables on reaction kinetics and the identification of readily available molecular descriptors for calculating reactivity. Toward these goals, studies were performed on the reduction of a series of monosubstituted nitrobenzenes in Fe(II)-treated goethite suspensions. The energy of the lowest unoccupied molecular orbital, E(LUMO) (B3LYP/6-31G*, water), of the nitrobenzenes was capable of explaining 99% of the variability in the rates. Results of experiments in which the surface area loading of ferric oxides was systematically varied indicate that (i) the reactivity of mineral-surface-associated Fe(II), Fe(II)surf, toward the reduction of p-cyanonitrobenzene (CNNB) decreased in the following order: hematite > goethite > lepidocrocite > ferrihydrite, and (ii) the surface density of Fe(II)surf did not play a crucial role in determining the observed reactivity trend. CNNB was reduced in Fe(II)-only control experiments in a pH range of 7.28 to 7.97 with a pH dependency consistent with the transformation of Fe(II) to Fe(OH)3 or related oxides. The pH dependency of the reduction of CNNB in Fe(II)-treated ferric oxide suspensions (pH 6.1-7.97) could be accounted for by the oxidation of Fe(II)surf, forming an Fe(III) oxide.

JOURNAL	Occurrence of a New Generation of Disinfection By-Products	12/01/2006

KRASNER, S. W., H. S. WEINBERG, S. D. RICHARDSON, S. J. PASTOR, R. CHINN, M. J. SCLIMENTI, G. D. ONSTAD, AND A. D. THRUSTON,JR. Occurrence of a New Generation of Disinfection By-Products. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(23):7175-7185, (2006).
Abstract:	A survey of disinfection by-product (DBP) occurrence in the United States was conducted at 12 drinking water treatment plants. In addition to currently regulated DBPs, more than 50 DBPs that rated a high priority for potential toxicity were studied. These priority DBPs included iodinated trihalomethanes (THMs), other halomethanes, a nonregulated haloacid, haloacetonitriles, haloketones, halonitromethanes, haloaldehydes, halogenated furanones, haloamides, and nonhalogenated carbonyls. The purpose of this study was to obtain quantitative occurrence information for new DBPs (beyond those currently regulated and/or studied) for prioritizing future health effects studies. THMs and haloacetic acids (HAAs) represented the two major classes of halogenated DBPs formed on a weight basis. Haloacetaldehydes represented the third major class formed in many of the waters. In addition to obtaining quantitative occurrence data, important new information was discovered or confirmed at full-scale plants on the formation and control of DBPs with alternative disinfectants to chlorine. Although the use of alternative disinfectants (ozone, chlorine dioxide, and chloramines) minimized the formation of the four regulated THMs, trihalogenated HAAs, and total organic halogen (TOX), several priority DBPs were formed at higher levels with the alternative disinfectants as compared with chlorine. For example, the highest levels of iodinated THMs, which are not part of the four regulated THMs, were found at a plant that used chloramination with no pre-chlorination. The highest concentration of dichloroacetaldehyde was at a plant that used chloramines and ozone; however, this disinfection scheme reduced the formation of trichloroacetaldehyde. Preozonation was found to increase the formation of trihalonitromethanes. In addition to the chlorinated furanones that have been measured previously, brominated furanones, which have seldom been analyzed, were detected, especially in high-bromide waters. The presence of bromide resulted in a shift to the formation of other bromine-containing DBPs not normally measured (e.g., brominated ketones, acetaldehydes, nitromethanes, acetamides). Collectively, approximately 30 and 39 percent of the TOX and total organic bromine, respectively, were accounted for (on a median basis) by the sum of the measured halogenated DBPs. In addition, 28 new, previously unidentified DBPs were detected. These included brominated and iodinated haloacids, a brominated ketone, and chlorinated and iodinated aldehydes.

JOURNAL	Uncertainty from Synergistic Effects of Multiple Parameters in the Johnson and Ettinger (1991) Vapor Intrusion Model	05/26/2006

TILLMAN, F. D. AND J. W. WEAVER. Uncertainty from Synergistic Effects of Multiple Parameters in the Johnson and Ettinger (1991) Vapor Intrusion Model. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 40(22):4098-4112, (2006).
Abstract:	Migration of volatile chemicals from the subsurface into overlying buildings is known as vapor intrusion (VI). Under certain circumstances, people living in homes above contaminated soil or ground water may be exposed to harmful levels of these vapors. Vapor intrusion is a particularly difficult pathway to assess, as challenges exist in delineating subsurface contributions to measured indoor-air concentrations as well as in adequate characterization of subsurface parameters necessary to calibrate a predictive flow and transport model. Often, a screening-level model is employed to determine if a potential indoor inhalation exposure pathway exists and, if such a pathway is complete, whether long-term exposure increases the occupants' risk for cancer or other toxic effects to an unacceptable level. A popular screening-level algorithm currently in wide use in the United States, Canada, and the U.K. for making such determinations is the Johnson and Ettinger (J&E) model. Concern exists over using the J&E model for deciding whether or not further action is necessary at sites as many parameters are not routinely measured (or are un-measurable). Many screening decisions are then made based on simulations using best estimate look-up parameter values. While research exists on the sensitivity of the J&E model to individual parameter uncertainty, little published information is available on the combined effects of multiple uncertain parameters and their effect on screening decisions. This paper presents results of multiple-parameter uncertainty analyses using the J&E model to evaluate risk to humans from vapor intrusion. Software was developed to produce automated uncertainty analyses of the model. Results indicate an increase in cancer risk from multiple-parameter uncertainty compared with single-parameter uncertainty by as much as 1285% for the case simulated. Additionally, a positive skew in model response to variation of some parameters was noted for both single and multiple parameter uncertainty analyses. From these results, an example order of data collection is presented to reduce output uncertainty. An on-line version of the model with automated uncertainty analyses is available to the public on EPA's Office of Research and Development website(http://www.epa.gov/athens/onsite).

JOURNAL	Biochemical and Genetic Characterization of An Early Step in a Novel Pathway for the Biosynthesis of Aromatic Amino Acids and P-Aminobenzoic Acid in the Archaeon Methanococcus Maripaludis	11/30/2006

PORAT, I., M. SIEPRAWSKA-LUPA, Q. TENG, F. J. BOHANON, R. H. WHITE, AND W. B. WHITMAN. Biochemical and Genetic Characterization of An Early Step in a Novel Pathway for the Biosynthesis of Aromatic Amino Acids and P-Aminobenzoic Acid in the Archaeon Methanococcus Maripaludis. Molecular Microbiology. Blackwell Publishing Limited, Oxford, Uk, 62(4):1117-1131, (2006).
Abstract:	Methanococcus maripaludis is a strictly anaerobic, methane-producing archaeon and facultative autotroph capable of biosynthesizing all the amino acids and vitamins required for growth. In this work, the novel 6-deoxy-5-ketofructose-1-phosphate (DKFP) pathway for the biosynthesis of aromatic amino acids (AroAAs) and p-aminobenzoic acid (PABA) was demonstrated in M. maripaludis. Moreover, PABA was shown to be derived from an early intermediate in AroAA biosynthesis and not from chorismate. Following metabolic labeling with [U13C]-acetate, the expected enrichments for phenylalanine and arylamine derived from PABA were observed. DKFP pathway activity was reduced following growth with aryl acids, an alternative source of the AroAAs. Lastly, a deletion mutant of aroA', which encodes the first step in the DKFP pathway, required AroAAs and PABA for growth. Complementation of the mutants by an aroA' expression vector restored the wild-type phenotype. In contrast, a deletion of aroB', which encodes the second step in the DKFP pathway, did not require AroAAs or PABA for growth. Presumably, methanococci contain an alternative activity for this step. These results identify the initial reactions of a new pathway for the biosynthesis of PABA in methanococci.

JOURNAL	Characterization of Fungi from Hypersaline Environments of Solar Salterns Using Morphological and Molecular Techniques	08/10/2006

CANTRELL, S. A., L. CASILLAS-MARTINEZ, AND M. MOLINA. Characterization of Fungi from Hypersaline Environments of Solar Salterns Using Morphological and Molecular Techniques. Mycological Research. Cambridge University Press, Cambridge, Uk, 110(8):962-970, (2006).
Abstract:	The Cabo Rojo Solar Salterns located on the southwest coast of Puerto Rico are composed of two main ecosystems (i.e., salt ponds and microbial mats). Even though these locations are characterized by high solar radiation (mean light intensity of 39 mol photons m-2d-1) they harbor a diverse microscopic life. We have used morphological and molecular techniques to identify a series of halotolerant fungi. A total of 183 isolates and 36 species were cultured in this study. From the water from the salt ponds, 86 isolates divided in 26 species were cultured. Some of the halotolerant fungi isolated from water are Cladosporium cladosporioides, nine Aspergillus sp., five Penicillium sp. and the black yeast Hortaea werneckii. A distinctive isolate with a blue mycelium was cultured from the salt ponds, representing a new species of Periconia based on morphology and ribosomal DNA analysis. From sediments around the salt ponds we cultured 44 isolates divided in 8 species. Most of the sediment isolates were identified as Mycelia Sterilia, while several were Chaetomium globosum. A total of 53 isolates divided in 16 species were isolated from the three layers of the microbial mats. In the three layers of the microbial mat, Aspergillus niger was the most frequent isolate. PLFA profiles generated from the different layers of the microbial mats indicated that the uppermost layers of the mats contained fungal biomarker, 18:2w6. This fatty acid decreased with depth, the highest concentration was observed in the green upper layer and it disappeared in the black bottom anoxic layer. This correlates with the isolation of fungi using the serial dilution technique. This is the first study that documents the presence of fungi in microbial mats.

JOURNAL	Bioaccumulation and Biotransformation of Chiral Triazole Fungicides in Rainbow Trout (Oncorhynchus Mykiss)	12/30/2006

KONWICK, B. J., A. W. GARRISON, J. K. AVANTS, AND A. T. FISK. Bioaccumulation and Biotransformation of Chiral Triazole Fungicides in Rainbow Trout (Oncorhynchus Mykiss). AQUATIC TOXICOLOGY. Elsevier Science Ltd, New York, NY, 80(4):372-381, (2006).
Abstract:	There are very little data on the bioaccumulation and biotransformation of current-use pesticides (CUPs) despite the fact that such data are critical in assessing their fate and potential toxic effects in aquatic organisms. To help address this issue, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to dietary concentrations of a mixture of chiral triazole fungicides (bromuconazole, cyproconazole, metconazole, myclobutanil,penconazole, propiconazole, tebuconazole, tetraconazole, and triadimefon) and a chiral legacy pesticide [alpha-hexachlorocyclohexane (alpha-HCH)] to study the bioaccumulation and biotransformation of these CUPs. Fish accumulated all triazoles rapidly during the 8 days uptake phase and was followed by rapid elimination, which was estimated by taking accelerated sampling times during the 16 days depuration period. Half-lives (t1/2s) and times to 95% elimination (t95s) ranged from 1.0 to 2.5 and 4.5 to 11.0 days, respectively. Chiral analysis suggested no significant selectivity in biotransformation for most of the compounds based on statistically unaltered enantiomer fractions (EFs) in the fish compared to food values; exceptions were a change in EF of myclobutanil and changes in diastereomer fractions (DFs) of propiconazole and cyproconazole. No biotransformation was observed for alpha-HCH based on consistent EFs in the fish throughout the experiment and a t1/2 (15.8 days) that fell within the 95% confidence interval of a log Kow-log t1/2 relationship developed for assessing biotransformation of organic contaminants. This relationship did show that biotransformation accounted for a majority (ranging from 59.9 to 90.4%) of the elimination for all triazoles, and that triazole compounds with oxygen and hydroxyl functional groups were more easily biotransformed. This research indicated that chiral analysis may potentially miss biotransformation of CUPs and other potential non-persistent organic contaminants and shows the utility of the log Kow-log t1/2 relationship as a mechanistic tool for quantifying biotransformation. Based on the rapid biotransformation of the triazoles, future research should focus on formation of metabolites and their fate and possible effects in the environment.

JOURNAL	Extending the Diffuse Layer Model of Surface Acidity Behavior: I. Model Development	08/01/2006

LOUX, N. T. Extending the Diffuse Layer Model of Surface Acidity Behavior: I. Model Development. CHEMICAL SPECIATION AND BIOAVAILABILITY. Science and Technology Letters, 18(3):105-116, (2006).
Abstract:	Considerable disenchantment exists within the environmental research community concerning our current ability to accurately model surface-complexation-mediated low-porewater-concentration ionic contaminant partitioning with natural surfaces. Several authors attribute this unacceptable variation to uncertainties in our understanding of surface acidity behavior. In support of this contention, many authors are not satisfied with our ability to model surface acidity behavior in controlled, pure phase laboratory systems. The present work was designed to more closely examine the theoretical aspects of those variable energies likely to be contributing to the excess free energies associated with surface acidity behavior.

PAPER IN NON-EPA PROCEEDINGS	Challenges of Passive Treatment of Metal Mine Drainage in the Iberian Pyrite Belt (Southern Spain): Preliminary Studies	03/30/2006

ROTTING, T. S., R. C. THOMAS, C. AYORA, AND J. CARRERA. Challenges of Passive Treatment of Metal Mine Drainage in the Iberian Pyrite Belt (Southern Spain): Preliminary Studies. In Proceedings, 2006 7th ICARD, St. Louis, MO, March 26 - 30, 2006. American Society of Mining and Reclamation, Lexington, KY, 1753-1767, (2006).
Abstract:	AMD in the Iberian Pyrite Belt is a problem of global scale. Successful implementation of passive treatment systems could remediate at least part of this problem at reasonable costs. However, initial trials with ALD and RAPS based on gravel size limestone failed due to rapid loss of chemical reactivity and plugging. Limestone buffered organic substrate (LBOS), which employs fine-grained limestone in an organic matrix, is an attractive alternative to conventional RAPS or ALD substrates, because it combines high reactivity with low plugging. However, LBOS has only been tested on ferric-iron waters, while our target AMD is mainly ferrous iron. Due to the high ferrous to ferric iron ratio, we envision a LBOS treatment system that relies on sulfate reducing bacteria (SRB) in addition to the fine-grained limestone in the substrate. This study presents preliminary batch and column trials on reactivity and hydraulic properties. Other challenges include finding appropriate and locally available LBOS components. Tested substrates include compost, wood chips, limestone screenings and sugar beet lime. Results show that only some SRB types tolerate the high metal concentrations. Reactors with SRB activity produce higher alkalinity, but support lower flow rates than reactors based on limestone dissolution only.

PAPER IN NON-EPA PROCEEDINGS	Watershed Health Assessment Tools-Investigating Fisheries (What-If): A Modeling Toolkit for Watershed and Fisheries Management	07/14/2006

RASHLEIGH, B., M. C. BARBER, M. J. CYTERSKI, J. M. JOHNSTON, Y. M. MOHAMOUD, AND R. S. PARMAR. Watershed Health Assessment Tools-Investigating Fisheries (What-If): A Modeling Toolkit for Watershed and Fisheries Management. In Proceedings, iEMSs Third Biennial Meeting: Summit on Environmental Modelling and Software, Burlington, VT, July 09 - 13, 2006. International Environmental Modelling and Software Society, Manno, Switzerland, Internet, (2006).
Abstract:	The Watershed Health Assessment Tools-Investigating Fisheries (WHAT-IF) is a decision-analysis modeling toolkit for personal computers that supports watershed and fisheries management. The WHAT-IF toolkit includes a relational database, help-system functions and documentation, and multiple statistical and simulation modeling tools. The tools consist of a hydrologic and stream geometry calculator, a fish assemblage predictor, a fish habitat suitability calculator, and a process-based model to predict biomass dynamics of stream biota (the BASS model). The tools can be used to assess conditions and associated stressors in aquatic ecosystems, to examine causes of impairment, and to forecast ecological outcomes of habitat alterations and fisheries management actions. WHAT-IF also supports screening analysis, such as prioritization of areas for restoration and comparison of alternative watershed and habitat management scenarios. The toolkit was originally developed for the Mid-Atlantic Highlands region of the U.S.; investigations are underway to transfer the technology to other regions.

PRESENTATION	U.S. Gasoline Composition Study	03/07/2006

WEAVER, J. W. U.S. Gasoline Composition Study. Presented at MTBE and Other Fuel Oxygenates: Comprehensive Site Assessment and Successful Groundwater Remediation Workshop, Reno, NV, March 06 - 07, 2006.
Abstract:	This presentation presents results from a 2004/2005 study of U.S. gasoline composition. Differences in composition are driven by regulation, octane requirements, refining methods, and performance needs. Major differences in composition were traced to a few compounds: benzene, MTBE, ethanol; and octane: iso-octanes, oxygenates, toluene.

PRESENTATION	Aqueous Protonation Properties of Amphoteric Nanoparticles	03/26/2006

LOUX, N. T. Aqueous Protonation Properties of Amphoteric Nanoparticles. Presented at 231st American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	A divergence is predicted between the acidity behavior of charged sites on micron sized colloidal particles and nanoparticles. Utilizing the approximate analytical solution to the Poisson-Boltzmann equation published by Ohshima et al. (1982), findings from the work included: 1): the excess free energy term associated with charge/potential relationships is given by: Del G excess,sigma/psi = Del G electrostatic + Del G hydration + Del G dipole + Del G Debye-Huckel, 2) the excess free energy terms included in effective acidity constant behavior includes a charging energy term: Del G excess,pK = Del G excess,sigma/psi + Del G charging, 3) Del G charging becomes increasingly significant with decreasing counterion condensation, and 4) hydration and charging energies impart an asymmetric behavior in the charge dependency of effective acidity constant behavior.

PRESENTATION	The Potential for the Use of Canines in Vapor Intrusion Investigations	03/20/2006

BIRD, S. L. The Potential for the Use of Canines in Vapor Intrusion Investigations. Presented at 18th Annual National Tanks Conference, Memphis, TN, March 20 - 22, 2006.
Abstract:	Dogs have been used extensively in law enforcement and military applications to detect narcotics and explosives for over thirty years and in arson investigations to detect accelerants since they are much more accurate at discriminating between accelerants and by-products of combustion than are field volatile organic compound (VOC) detectors. Relatively few environmental applications, however, have taken advantage of this canine capability. Detection dogs have the potential to rapidly screen houses for vapor intrusion of a variety of VOCs from contaminated groundwater sources. Dogs can rapidly screen for the presence of a substance in indoor air and are also capable of moving towards the source of volatile materials. The primary learning objective of this presentation is to provide the audience member with an understanding of the potential and limitations of using dogs in vapor intrusion investigations. An operational demonstration of scent detection dogs will be included in the presentation.

PRESENTATION	The Comparison of Two Watersheds Using a Watershed Nutrient Loading Model	05/16/2006

FRICK, W. E., A. C. SIGLEO, AND L. M. PRIETO. The Comparison of Two Watersheds Using a Watershed Nutrient Loading Model. Presented at Second Interagency Conference on Research in the Watersheds, Otto, NC, May 16 - 18, 2006.
Abstract:	Monitoring data, collected from the Yaquina River, Oregon, from 1999 through 2002 were used as the basis for developing the nutrient flux model as part of a larger agency program for quantifying nutrient processes. The PNWL nitrate loading model indicates that the nitrate load is generally a direct function of water discharge normalized to drainage area. The relationship is least accurate during the first major storm event of the water year in the fall. The dissolved nitrate concentrations during the first fall storm event tend to exceed those of the predicted nitrate values possibly due to the washout of nutrients during the first storm. The nitrate source in the freshwater reaches of Oregon coastal rivers is due primarily to nitrogen leaching from litter fall in alder stands in the surrounding watershed. The highest concentrations occurred during winter periods of higher runoff, whereas the lowest concentrations occurred during late summer and low river flow. To test the predictive ability of the model for other Oregon coastal rivers, empirical data from the nearby Alsea River were compared with the nitrate concentrations predicted by the model. The results indicated that the model provides a reasonable first estimate of nitrate concentrations from water discharge data, which may then be used to calculate nutrient loads. However, the model appears to predict slightly higher values than expected for the Alsea. Differences between predicted and observed concentrations may be reduced by adjusting the model coefficients. However, they may reflect watershed differences, not just statistical variations. For example proximate source areas may be more important than distal ones in determining nitrate concentrations.

PRESENTATION	Transport, Air-Surface Exchange and Landscape Accumulation of Airborne Pollutants Deposited Onto Rural Catchments: the Case of Mercury	05/24/2006

TSIROS, I. X. AND R. B. AMBROSE. Transport, Air-Surface Exchange and Landscape Accumulation of Airborne Pollutants Deposited Onto Rural Catchments: the Case of Mercury. Presented at 8th Conference on Meteorology-Climatology Atmospheric Physics, Athens, GREECE, May 24 - 26, 2006.
Abstract:	This paper presents a modeling analysis of airborne mercury fate in rural catchments by coupling components of simulation models developed and published previously by the authors. Results for individual rural catchments are presented and discussed, with a focus on the major mercury mass balance components: hydrologic transport, air-surface exchange, and accumulation in the watershed soils. Sensitivity analyses are performed to evaluate parameters controlling the predicted mercury loading fluxes, including intra- and inter-annual weather variability, landscape characteristics, and other environmental parameters. Simulations were designed to calculate mercury flux response to microclimatic and other environmental variables for several mercury concentration level scenarios. We conclude, finally, that the models used in the present study are suited for use in linked atmospheric-hydrologic mercury modeling studies for assessing acceptable loadings of mercury to the atmosphere to protect environmental quality in rural watersheds.

PRESENTATION	Organophosphate Pesticide Degradation in the Presence of Naturally Occurring Aquatic Constituents Under Drinking Water Treatment Conditions	06/12/2006

DUIRK, S. E., C. TARR, AND T. W. COLLETTE. Organophosphate Pesticide Degradation in the Presence of Naturally Occurring Aquatic Constituents Under Drinking Water Treatment Conditions. Presented at American Water Works Association Annual Conference, San Antonio, TX, June 11 - 15, 2006.
Abstract:	Little work to date has solely investigated the kinetics and pathways of pesticide transformations under drinking water treatment conditions. Free chlorine has been found to react with s-triazine, carbamate, and organophosphate pesticides. However, these experimental conditions did not account for naturally occurring aquatic constituents such as natural organic matter (NOM) or inorganic ions (i.e., bromide). The kinetics and degradation pathways for chlorpyrifos (CP), an OP pesticide, have been established in buffered deionized water. However, the effect of NOM and bromide on the rate of CP has yet to be thoroughly investigated. This research was designed to examine the influence of NOM and bromide on the loss of CP in the presence of free chlorine.

PRESENTATION	Modeling Mercury in Stream Ecosystems	05/08/2006

AMBROSE, R. B. Modeling Mercury in Stream Ecosystems. Presented at 5th National Monitoring Conference, San Jose, CA, May 07 - 11, 2006.
Abstract:	Mercury is a classic multimedia pollutant. Natural and anthropogenic emissions are driven by a complicated set of transport and transformation reactions operating on a variety of scales in the atmosphere, landscape, surface water, and biota. In the past 15 years, surface water mercury model development has focused on lake ecosystems. Given our present understanding of environmental mercury transport, this presentation summarizes important components of a robust riverine mercury modeling system, from the upland watershed through the flood plains, riparian wetlands, the drainage network, and the underlying sediments. The important hydrological, transport, and transformation processes that should be included in riverine mercury models are highlighted, along with the key solids and mercury variables.

PRESENTATION	Estimating and Projecting Impervious Cover in the Southeastern United States	05/08/2006

HARRISON, J., L. R. EXUM, S. L. BIRD, AND C. PERKINS. Estimating and Projecting Impervious Cover in the Southeastern United States. Presented at 5th National Monitoring Conference, San Jose, CA, May 07 - 11, 2006.
Abstract:	Urban/suburban land use constitutes the fastest growing land use class in the Southeastern United States. Predominant development practices increase impervious surface--areas preventing infiltration of water into the underlying soil. Uncontrolled increase of impervious areas (roads, buildings and parking) causes detrimental hydrologic changes, stream channel erosion, habitat degradation and severe impairment of aquatic communities. Development practices that reduce impervious area and include preventative strategies to protect water quality are more effective and less costly than remedial restoration efforts. Simple and reliable methods to estimate and project impervious cover can help identify areas where a watershed is at risk of changing rapidly from a system with relatively pristine streams to one with significant symptoms of degradation. We provide a multiple data source (MDS) estimation of imperviousness in the Southeastern U.S. In this study, a method for estimating and projecting impervious cover for 12/14 digit hydrologic unit codes (HUCs) over a large area was developed and tested. These methods were applied throughout EPA Region 4?s eight southeastern states to provide a screening tool to guide monitoring and educational efforts.

PRESENTATION	Dynamic Changes in Colored Dissolved Organic Matter and Total Suspended Matter Control UV Exposure of Coral Reefs in the Florida Keys	02/20/2006

ZEPP, R. G., G. C. SHANK, E. BARTELS, E. STABENAU, W. S. FISHER, AND C. FICHOT. Dynamic Changes in Colored Dissolved Organic Matter and Total Suspended Matter Control UV Exposure of Coral Reefs in the Florida Keys. Presented at 2006 Ocean Sciences Meeting, Honolulu, HI, February 20 - 24, 2006.
Abstract:	Variation in ultraviolet (UV) light exposure is one important environmental factor that influences the health of coral reefs. Here we present evidence that the reef tract in the Florida Keys experiences significantly higher variability in UV exposure than other surrounding coastal waters of South Florida. The variability is attributable primarily to fluctuations in the nature and concentration of colored dissolved organic matter (CDOM) and total suspended matter (TSM) over the reefs. The dynamic changes in CDOM are related to a combination of natural and human factors. In this presentation we use a new technique based on remotely sensed ocean color to estimate UV attenuation in the Florida Keys region. Relationships between visible remote sensing reflectance, UV attenuation, and absorption by colored dissolved organic matter (CDOM) in the ocean water are applied to SeaWiFS normalized water-leaving radiances to calculate the CDOM absorption and UV attenuation for the water over the coral reefs. Using this approach we demonstrate that patch reefs in the Keys that are well protected from UV radiation by CDOM and TSM have significantly higher coral cover than the reefs that receive higher and more variable exposure.

PRESENTATION	Development of a Structure-Searchable Database for Pesticide Metabolites and Environmental Degradates	03/05/2006

PROTZEL, A., G. DANNAN, R. C. KOLANCZYK, O. MEKENYAN, S. ABEL, P. K. SCHMIEDER, AND W. J. JONES. Development of a Structure-Searchable Database for Pesticide Metabolites and Environmental Degradates. Presented at Society for Toxicology Annual Meeting, San Diego, CA, March 05 - 09, 2006.
Abstract:	USEPA is modifying and enhancing existing software for the depiction of metabolic maps to provide access via structures to metabolism information and associated data in EPA's Office of Pesticide Programs (OPP). The database includes information submitted to EPA in support of pesticide registration such as pesticide metabolism in laboratory animals, plants, livestock, in addition to environmental degradates. The database will be used by OPP risk assessors to increase efficiency of data access and performance of risk assessments. The system includes the ability to: depict hierarchical connection sequences of parent chemical and all listed metabolites; track radiolabel within a pathway and combine/separate maps from associated radiolabel studies; identify all maps (and the parent chemical structure) that contain a specific metabolite of concern; search for specific sub-structures of toxicological concern and indicate its presence across chemicals; and, compare complete maps across chemicals and species. Associated chemical identifiers and tracking information is included, as well as bioassay and analytical chemistry. In its simplest mode, the database will furnish curated structures of pesticides and their metabolites suitable for searches in other databases, provide metabolic maps plus tabulations of amounts of metabolites, and other parameters. In a more advanced mode, the database may be used by risk assessors to perform substructure searches for types of compounds and toxicophores, and to identify metabolism commonalities and differences across pesticides and species. At present, some of these questions are answered manually and the results may vary among individual risk assessors. The database is expected to make this process more efficient, to furnish more reliable results, and to serve as a tool for hypothesis formulation by EPA researchers.

PRESENTATION	1h-Nmr Metabolomics Analyis of Zebrafish (Danio Rerio) Exposed to the Environmentally-Relevant EDC 17 Alpha-Ethinylestradiol (Ee2)	03/26/2006

WHITEHEAD, T. L., D. R. EKMAN, E. J. DURHAN, K. M. JENSEN, M. D. KAHL, E. A. MAKYNEN, D. L. VILLENEUVE, AND G. T. ANKLEY. 1h-Nmr Metabolomics Analyis of Zebrafish (Danio Rerio) Exposed to the Environmentally-Relevant EDC 17 Alpha-Ethinylestradiol (Ee2). Presented at American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	Elevated levels of endocrine-disrupting chemicals (EDCs) have been reported in waterways worldwide and have been shown to affect numerous aspects of development, behavior, reproduction, and survival in various fish species. We have examined the effects of the synthetic steroid 17 alpha-ethinylestradiol (EE2) on endogenous metabolite levels in tissue and plasma from reproductively mature zebrafish (Danio rerio). EE2 is a highly specific and potent agonist of the estrogen receptor used extensively in the U.S. as an active ingredient in oral contraceptives. It has been observed in aquatic environments and is therefore considered relevant as an environmental contaminant. Fish were exposed to two concentrations of EE2 (30 or 100 ng/L) or control water for up to 96 hours in a flow-through system. Endogenous metabolites were detected in brain, liver and gonad extracts and in native plasma using 1H-NMR spectroscopy. PCA and PLS-DA techniques were employed to define metabolites responsible for class separation between control, low-dose exposure, and high-dose exposure populations. Ultimately, differential metabolic profiles will provide predictive biomarkers for risk assessment and support computational toxicology modeling efforts to characterize toxicity pathways of environmentally-relevant compounds in a systems- and population-modeling context.

PRESENTATION	Aqueous Chlorination of Chlorpyrifos in the Presence of Bromide and Natural Organic Matter	03/26/2006

DUIRK, S. E., C. J. TARR, AND T. W. COLLETTE. Aqueous Chlorination of Chlorpyrifos in the Presence of Bromide and Natural Organic Matter. Presented at American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	The rates and pathways for pesticide transformation under drinking water treatment conditions are known for only a few pesticides and only under limited conditions. For example, it is known that chlorine reacting with organophosphate (OP) pesticides that contain the thiophosphate functionality (P=S) often results in the formation of oxons (P=O). The resulting oxons are more toxic than the parent pesticides. The transformation rates and pathways for chlorpyrifos (CP), an OP pesticide, have been established in buffered deionized water. However, the effects of naturally occurring aquatic constituents have yet to be thoroughly investigated. This work expands our understanding of the influence of bromide and natural organic matter (NOM), two important naturally occurring constituents, on CP degradation in treated water. Also, results are interpreted with the aid of a model capable of predicting CP degradation pathways in the presence of free chlorine.

PRESENTATION	Aqueous Chlorination of Chlorpyrifos in the Presence of Bromide and Nom	03/26/2006

DUIRK, S. E., C. J. TARR, AND T. W. COLLETTE. Aqueous Chlorination of Chlorpyrifos in the Presence of Bromide and Nom. Presented at American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	The rates and pathways for pesticide transformation under drinking water treatment conditions are known for only a few pesticides and only under limited conditions. For example, it is known that chlorine reacting with organophosphate (OP) pesticides that contain the thiophosphate functionality (P=S) often results in the formation of oxons (P=O). The resulting oxons are more toxic than the parent pesticides. The transformation rates and pathways for chlorpyrifos (CP), an OP pesticide, have been established in buffered deionized water. However, the effects of naturally occurring aquatic constituents have yet to be thoroughly investigated. This work expands our understanding of the influence of bromide and natural organic matter (NOM), two important naturally occurring constituents, on CP degradation in treated water. Also, results are interpreted with the aid of a model capable of predicting CP degradation pathways in the presence of free chlorine.

PRESENTATION	Occurrence of Iodo-Acid and Iodo-Thm DBPs in U. S. Chloraminated Drinking Waters	03/26/2006

RICHARDSON, S. D., F. G. CRUMLEY, J. J. ELLINGTON, J. J. EVANS, B. C. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, AND E. D. WAGNER. Occurrence of Iodo-Acid and Iodo-Thm DBPs in U. S. Chloraminated Drinking Waters. Presented at American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	Iodo-acids were recently identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid (IAA), bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. There is concern about these new iodo-acid DBPs because mammalian cell toxicity studies have revealed that IAA is highly cytotoxic and genotoxic - with a genotoxicity 2X that of regulated bromoacetic acid. New evidence indicates that iodinated DBPs may be increased in formation in chloraminated vs. chlorinated drinking water, and this is of concern because many water utilities are switching from chlorine to chloramines. We developed a negative chemical ionization mass spectrometry method to measure these iodo-acids in drinking water and are conducting a large occurrence study of these iodo-acids in chloraminated drinking waters across the U.S.

PRESENTATION	Occurrence and Toxicity of Iodo-Acid Disinfection By-Products in Chloraminated Drinking Water	03/16/2006

RICHARDSON, S. D., J. J. ELLINGTON, F. G. CRUMLEY, J. J. EVANS, M. J. PLEWA, AND E. D. WAGNER. Occurrence and Toxicity of Iodo-Acid Disinfection By-Products in Chloraminated Drinking Water. Presented at Symposium "Safe Drinking Water: Where Science Meets Policy.", Chapel Hill, NC, March 16 - 17, 2006.
Abstract:	As part of a recent Nationwide Disinfection By-Product (DBP) Occurrence Study, iodo-acids were identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid (IAA), bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. There is concern about these new iodo-acid DBPs because mammalian cell cytotoxicity and genotoxicity studies have revealed that IAA is highly cytotoxic and genotoxic, with a genotoxicity potency 2X higher than bromoacetic acid, the most genotoxic of the regulated haloacetic acids (HAAs). Also, many drinking water treatment plants in the United States have switched from chlorine to chloramines for treatment. New evidence indicates that iodinated DBPs may be increased in formation in chloraminated vs. chlorinated drinking water. The goal of this work was to develop an analytical method to quantify these five iodo-acids in drinking water, measure their occurrence in drinking waters treated with chloramination, and investigate the toxicity of the four synthesized iodo-acids (beyond IAA). An initial sampling of chloramine drinking water treatment plants conducted in May 2005 revealed IAA in all finished waters; bromoiodoacetic acid in 4 of the 5 finished waters; and the other iodo-acids in one of the finished waters. The highest level was 1.7 ppb (for IAA) in waters from two cities. The study was then expanded in the fall of 2005 to include 22 cities - 21 cities in the U.S. and one in Canada--that use chloramination. These samples are currently being analyzed, and data from these samples will be presented, along with new toxicity information.

PRESENTATION	Estimation of Phosphate Ester Hydrolysis Rate Constants Alkaline Hydrolysis	03/22/2006

WHITESIDE, T. S., S. H. HILAL, AND L. A. CARREIRA. Estimation of Phosphate Ester Hydrolysis Rate Constants Alkaline Hydrolysis. Presented at American Chemical Society National Meeting, Atlanta, GA, March 26 - 30, 2006.
Abstract:	SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition states of a molecule. This difference is a function of the reference rate and internal and external perturbations to the reference rate. The internal perturbations are comprised of electrostatic and resonance effects. The external perturbations quantify solute-solvent interactions based on the dielectric constant of the solvent and the steric effect of substituent groups. These perturbation models have been tested using 225 reliably measured second order hydrolysis rate constants over a range of temperatures. The RMS deviation of the calculated versus observed values was 0.401 log M-1s-1.

PRESENTATION	Project Summary: Development of the Virtual Beach Model, Phase I: An Empirical Model	01/18/2006

FRICK, W. E. AND Z. GE. Project Summary: Development of the Virtual Beach Model, Phase I: An Empirical Model. Presented at NOAA's Oceans and Human Health Initiative All PI's 2006 Annual Meeting, Charleston, SC, January 18 - 20, 2006.
Abstract:	Mathematical models based on water-quality and other environmental surrogates may help to provide water quality assessment within a few hours and potentially provide one to three day forecasts, providing beach managers and public-health officials a tool for developing beach-specific predictive models for their own beaches, with the goal of making beaches swimmable as much as possible. The USEPA, Office of Research Development, is working on developing such as tool called "Virtual Beach." Because considerable experience in developing predictive statistical models is required, the USEPA is collaborating with USGS (Columbus) to incorporate their experience and modeling procedures and approaches into Virtual Beach. This paper is a project summary of work accomplished so far.

PRESENTATION	Pops in Alligator Livers from Lake Apopka, Florida, USA	03/29/2006

GARRISON, A. W., L. J. GUILLETTE, JR., T. E. WIESE, AND J. K. AVANTS. Pops in Alligator Livers from Lake Apopka, Florida, USA. Presented at 1st Network Conference on Persistent Organic Pollutants, Birmingham, UK, March 29 - 30, 2006.
Abstract:	Reproductive disorders in American alligators (Alligator mississippiensis) inhabiting Lake Apopka, Florida, have been observed for several years. Such disorders are hypothesized to be caused by endocrine disrupting contaminants occurring in the Lake due to pesticide spills and runoff from bordering agricultural lands, and various studies have resulted in identification of several POPs (persistent organic pollutants), some of them known endocrine disrupters. However, previous studies have not determined the enantiomer composition of any chiral POPs identified, although it is known that enantiomers of chiral pesticides often differ in their biological activity, including endocrine disruption. In this study, livers from 10 juvenile alligators inhabiting Lake Apopka were extracted and analyzed using chiral gas chromatography-mass spectrometry for identification of organochlorine pesticides; in so doing, the enantiomer fractions of any chiral pesticides identified were also measured. In summary, p,p'-DDE was the most prominent POP (persistent organic pollutant) identified.

PRESENTATION	Watershed Health Assessment Tools-Investigating Fisheries (What-If): A Modeling Toolkit for Watershed and Fisheries Management	07/10/2006

RASHLEIGH, B., M. C. BARBER, M. J. CYTERSKI, J. M. JOHNSTON, Y. M. MOHAMOUD, AND R. S. PARMAR. Watershed Health Assessment Tools-Investigating Fisheries (What-If): A Modeling Toolkit for Watershed and Fisheries Management. Presented at International Environmental Modelling and Software Society Conference, Burlington, VT, July 09 - 13, 2006.
Abstract:	The Watershed Health Assessment Tools-Investigating Fisheries (WHAT-IF) is a decision-analysis modeling toolkit for personal computers that supports watershed and fisheries management. The WHAT-IF toolkit includes a relational database, help-system functions and documentation, and multiple statistical and simulation modeling tools. The tools consist of a hydrologic and stream geometry calculator, a fish assemblage predictor, a fish habitat suitability calculator, and a process-based model to predict biomass dynamics of stream biota (the BASS model). The tools can be used to assess conditions and associated stressors in aquatic ecosystems, to examine causes of impairment, and to forecast ecological outcomes of habitat alterations and fisheries management actions. WHAT-IF also supports screening analysis, such as prioritization of areas for restoration and comparison of alternative watershed and habitat management scenarios. The toolkit was originally developed for the Mid-Atlantic Highlands region of the U.S.; investigations are underway to transfer the toolkit to other regions.

PRESENTATION	Statistical Basis for Dynamic Prediction of Beach Bacteria Concentrations	01/20/2006

GE, Z. AND W. E. FRICK. Statistical Basis for Dynamic Prediction of Beach Bacteria Concentrations. Presented at NOAA's Oceans and Human Health Initiative All PI's 2006 Annual Meeting, Charleston, SC, January 18 - 20, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Water Quality Modeling Research	01/24/2006

AMBROSE, R. B., R. A. BURKE, W. E. FRICK, E. J. HAYTER, J. M. JOHNSTON, S. R. KRAEMER, J. W. WASHINGTON, B. R. FAULKNER, M. M. HANTUSH, P. M. MAYER, AND E. A. STRIZ. Water Quality Modeling Research. Presented at Water Quality BOSC Review, Cincinnati, OH, January 23 - 25, 2006.
Abstract:	The multi-year planning science question of what additions to models are most needed for the TMDL process for priority stressors is addressed. Our research provides both the needed process research and the necessary technology (watershed hydrologic, hydrodynamic, and water quality models) to address bacteria, sediment and toxic stressors.

PRESENTATION	Testing New Capabilities for Simulating Free and Dissolved Phase Transport Using Mt3dms	10/16/2006

TONKIN, M., J. W. WEAVER, C. ZHENG, AND J. HAAS. Testing New Capabilities for Simulating Free and Dissolved Phase Transport Using Mt3dms. Presented at Conference for Association for Environmental Health and Sciences, Amherst, MA, October 16 - 19, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Occurrence of Iodo-Acid and Iodo-Thm DBPs in Chloraminated Drinking Waters in the U.S.	01/30/2006

RICHARDSON, S. D., F. G. CRUMLEY, J. J. ELLINGTON, J. J. EVANS, B. C. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, AND E. D. WAGNER. Occurrence of Iodo-Acid and Iodo-Thm DBPs in Chloraminated Drinking Waters in the U.S. Presented at AWWA Inorganic Contaminants Workshop, Austin, TX, January 29 - 31, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Thermodynamic Reaction Constants for Modeling Aqueous Environmental Mercury Speciation	08/09/2006

LOUX, N. T. Thermodynamic Reaction Constants for Modeling Aqueous Environmental Mercury Speciation. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	Unacceptably high fish tissue mercury residues are responsible for the majority of fish consumption advisories issued in 48 states of the United States of America. Mercury also has emerged as a transboundary contaminant of global concern. Although monomethylmercury is generally considered to be the problematic species of the element, the environmental fate and transport behavior of mercury is heavily influenced by the complex speciation behavior of all compounds of mercury in environmental (and biological) matrices. As with all environmental ionic toxicants, ionic mercury may react with a suite of soluble inorganic ligands, immobile ionic binding sites on environmental surfaces, and reactive ionic sites on naturally occurring dissolved and particulate organic carbon. Understanding the complex environmental speciation behavior of ionic mercury is made possible only by employing geochemical equilibrium speciation models to describe these various and competing simultaneous equilibrium reactions. The application of equilibrium speciation models in turn requires not only datasets of representative environmental analytical data, but also a suite of thermodynamic reaction constants that adequately represent the energetics of these reactions. Given the long and distinguished history of mercury investigations in the field of chemistry, those reaction constants describing complexation (and solubility) reactions between mercurous and mercuric mercury and inorganic ligands are relatively well represented in compendia published by authors including Sillen, Martell, Smith, Lindsay, Sadiq, and Rai and coworkers. Listings of thermodynamic constants describing reactions between monomethylmercury and environmental inorganic ligands are much less mature. Lastly, tables of constants for describing complexation reactions between ionic mercury species and immobile sites on environmental surfaces and with dissolved and particulate organic carbon can be viewed as listings of model-dependent parameters. This work will report on recent findings in the development of thermodynamic reaction constants for simulating problematic environmental mercury complexation phenomena.

PRESENTATION	Comparison of Direct and Indirect Impacts of Fecal Contamination in Two Different Watersheds	05/22/2006

LEE, Y. J. AND M. MOLINA. Comparison of Direct and Indirect Impacts of Fecal Contamination in Two Different Watersheds. Presented at American Society for Microbiology 106th General Meeting, Orlando, FL, May 21 - 25, 2006.
Abstract:	There are many environmental parameters that could affect the accuracy of microbial source tracking (MST) methods. Spatial and temporal determinants are among the most common factors missing in MST studies. To understand how spatial and temporal variability affect the level of fecal contamination in surface waters and the sensitivity of MST methods, we sampled the streams of two cattle farms located in different watersheds: cows have unrestricted access to one, while the other is affected only by runoff. Anaerobic fecal bacteria such as Bacteroides are more abundant than other indicator bacteria such as E. coli, making it a good fecal indicator in surface waters. However, it is possible that Bacteroides might persist in anaerobic sediments for extended periods of time questioning its use as an indicator of recent fecal contamination. To test this, we employed Bacteroides-specific molecular probes to detect fecal contamination in surface waters and sediments. Bacteroides signatures were detected over time in both water and sediment samples in both watersheds regardless of the type of cattle impact or the presence of runoff due to rain events. The watershed impacted directly by cow feces showed more stable and higher level of indicators than the watershed impacted only by fecal runoff. Bacteroides signatures from the watershed under indirect cattle impact suggest that this marker might survive longer than expected in the environment. Results also suggest that spatial variation is one of the most important factors affecting the applicability of the tested MST methods.

PRESENTATION	Comparing and Linking Plumes Across Modeling Approaches	02/20/2006

FRICK, W. E., Z. GE, T. KHANGAONKAR, AND D. SCHWAB. Comparing and Linking Plumes Across Modeling Approaches. Presented at 2006 Ocean Sciences Meeting, Honolulu, HI, February 20 - 24, 2006.
Abstract:	River plumes carry many pollutants, including microorganisms, into lakes and the coastal ocean. The physical scales of many stream and river plumes often lie between the scales for mixing zone plume models, such as the EPA Visual Plumes model, and larger-sized grid scales for regional circulation models, such as the Princeton Ocean Model (POM) used to simulate Great Lakes circulation. A potential advantage of the smaller scale models is that they frequently use entrainment theory to simulate the growth of plumes, a technique that has proven useful in simulating turbulent plumes discharged from various channels and structures, some approaching the dimensions of rivers. This study explores the overlap and potential for linkage of some of these models. A comparison of predictions is also presented. Applications for both the Great Lakes (Burns Ditch, near Porter, Indiana) and the coastal ocean are included.

PRESENTATION	Modeling Mercury Dynamics in Stream Systems With Wasp7: Characterizing Processes Controlling Short and Long Term Response	08/08/2006

WOOL, T. A., R. B. AMBROSE, AND C. D. KNIGHTES. Modeling Mercury Dynamics in Stream Systems With Wasp7: Characterizing Processes Controlling Short and Long Term Response. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	Mercury transport through stream ecosystems is driven by a complicated set of transport and transformation reactions operating on a variety of scales in the atmosphere, landscape, surface water, and biota. Riverine systems typically have short residence times and can experience large fluctuations in flow, depth, and velocity. Rivers are intimately connected to their drainage basins from which they receive both pollutant loads and dilution water. Important components of a riverine mercury modeling system include the upland watershed through the flood plains, riparian wetlands, the drainage network, and the underlying sediments. WASP7 is a dynamic, mass balance framework for modeling contaminant transport and fate in surface water systems. The WASP7 mercury module simulates Hg0, Hg(II), and MeHg, as well as silt, sand, and particulate organic matter. Linkage is provided through external files from watershed loading models, including WCS and GBMM, and to aquatic food web models, including BASS. The relative importance of watershed loading, in-stream transport, and mercury transformation processes in controlling short and long-term mercury response is investigated in a case study of mercury fate in Brier Creek, Georgia. WASP7 first simulated long-term mercury buildup in the sediment layers. Finer scale simulations were then run, calculating mercury dynamics under current conditions. Model parameters were calibrated to available water column and sediment mercury data, and sensitivity analyses were conducted to determine the key parameters and forcing functions controlling short and long-term mercury fate in this stream. This case study provides a realistic example of the capabilities and limitations of stream mercury simulations. Data needs to support WASP7 applications to mercury dynamics in riverine ecosystems are itemized, and a collaborative monitoring, process science, and model development program is recommended.

PRESENTATION	Challenges and Successes Modeling the Influences of Land Use Changes on Mercury Dynamics	08/06/2006

TSIROS, I. X., R. B. AMBROSE, AND C. D. KNIGHTES. Challenges and Successes Modeling the Influences of Land Use Changes on Mercury Dynamics. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	Linked sets of atmospheric, watershed, water body, and food web models and supporting data are required to evaluate the effectiveness of proposals to regulate atmospheric mercury emissions. Simulating mercury dynamics in watersheds is a key step linking changes in atmospheric deposition with changes in stream loading rates. This step is challenged by uncertainties in mercury fate process descriptions, incomplete empirical datasets, and gaps in simulation technology. Case studies indicate that land use and vegetative cover strongly influence mercury accumulation and subsequent runoff and erosion loading rates. Land use changes, then, significantly complicate long-term hind casts and forecasts of watershed mercury fate. A small number of field-scale and watershed-scale models have been developed and applied to watershed mercury cycling, including WARMF, WCS-Mercury, GBMM, and GLEAMS-Hg. The loading, transport, and transformation processes controlling mercury cycling through watersheds are summarized, and their implementation in this set of simulation models is reviewed. Uncertainties and differences in process descriptions are highlighted, and areas of convergence are noted. Most of these watershed mercury cycling processes are strongly affected by land use and vegetative cover. Simple example calculations of mercury accumulation and delivery rates are provided for different land use scenarios. In particular, disturbed and impervious surfaces should more efficiently deliver mercury deposited from the atmosphere. Modeling case studies are reviewed to highlight the relative contributions of different land uses on watershed loading rates. Calculations of watershed mercury loading rates under changing land use patterns are presented. These calculations are suggestive, but highly uncertain. Given present uncertainties, watershed models can be used to bound the timing and extent of load reductions following changes in mercury deposition rates, and to explore factors that might complicate the watershed response. Additional watershed mercury data would help to constrain model calibrations somewhat, giving more accurate runoff and loading calculations. To reduce predictive uncertainties, however, better descriptions of processes controlling mercury transport and fate processes are needed.

PRESENTATION	Data Tools and Interpretation	02/10/2006

RASHLEIGH, B. Data Tools and Interpretation. Presented at Georgia River Network Conference, Milledgeville, GA, February 10, 2006.
Abstract:	As watershed groups in the state of Georgia form and develop, they have a need for collecting, managing, and analyzing data associated with their watershed. Possible sources of data for flow, water quality, biology, habitat, and watershed characteristics include the U.S. Geological Survey, U.S. EPA, and the state of Georgia. Some considerations for data management include the following: data standardization, documentation and metadata, and data verification. Data should be examined for outliers that can indicate possible pollution problems. Possible analyses for watershed data include correlation, regression, and multivariate analysis. Summarizing data with statistics and presenting it in report form makes it more informative and easier to understand and detect patterns in the watershed.

PRESENTATION	Characterization of PCB Bioaccumulation in the Lake Hartwell Foodweb Using the Aquatox Model	07/18/2006

RASHLEIGH, B., M. C. BARBER, AND D. WALTERS. Characterization of PCB Bioaccumulation in the Lake Hartwell Foodweb Using the Aquatox Model. Presented at VIIth International Congress on the Biology of Fish, St. John's, NL, CANADA, July 18 - 22, 2006.
Abstract:	PCBs from the Sangamo-Weston Superfund Site near Clemson, South Carolina, USA, were released into the Twelvemile Creek arm of Lake Hartwell until the early 1990s. Monitoring data have shown that while PCB concentration in sediments declined since 1995, PCB concentrations in largemouth bass have remained in the range of 5-10 ppm. The EPA aquatic ecosystem model AQUATOX was applied to this system to better understand food web dynamics and characterize bioaccumulation. The model was parameterized with available flow, nutrients, and TOC data, calibrated with observed fish biomass data, and then initialized with measured PCB values in water (0.05ug/L), sediment (5 ppm), and fish. According to model results, PCB loadings at approximately half the initial conditions were necessary to simulate fish PCB concentrations in the range of observed data over a 5-year period. The model demonstrated that contaminated detritus loaded to the system was incorporated into the food chain through direct consumption and ingestion by benthic organisms. More detritial PCB was consumed than deposited (17% vs. 4%), thereby maintaining the PCB concentrations in fish while the concentrations in the sediment declined. The model can be used to estimate the time needed for PCB concentrations in fish to be reduced to target levels for recovery (>2.0 ppm).

PRESENTATION	Use of Tracer Injection Experiments to Quantify Nitrate Loss in Two Adjacent Wetland Streams Draining An Agricultural Field in the Georgia Piedmont	02/09/2006

SCHROER, K. L., R. C. THOMAS, D. M. ENDALE, J. W. WASHINGTON, AND V. NZENGUNG. Use of Tracer Injection Experiments to Quantify Nitrate Loss in Two Adjacent Wetland Streams Draining An Agricultural Field in the Georgia Piedmont. Presented at 2006 USDA-CSREES National Water Conference, San Antonio, TX, February 05 - 09, 2006.
Abstract:	This study investigated the extent to which nitrate was removed from and/or stored in a small wetland depression downgradient of a 10-ha cattle rotational grazing pasture and a 2.5-ha cropped catchment at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center in Watkinsville, GA. A stream originates at a perennial spring at the base of the pasture and is protected from surface runoff by a berm. An adjacent stream is open to surface runoff from part of the pasture and receives shallow groundwater from the cropped catchment and part of the pasture but does not have a discrete perennial spring. The two streams join approximately 60m downstream. Background NO3--N concentrations in the two stream channels generally decrease from 0.43-0.86mM (6-12mg/L) at the source to 0.04-0.36mM (0.5-5mg/L) at their confluence, with more loss observed along the runoff stream. Daily load calculations and natural chloride concentrations indicate that dilution by ground water flux does not fully account for nitrate loss. We performed four seasonal stream tracer injection experiments in the spring-fed channel and one in the run-off channel. We injected nitrate and bromide at constant rates for 30 minutes and sampled intensively at several sampling locations throughout the day until field measurements of [NO3-] reached pre-injection background levels. In addition, at one control station in each stream, we sampled several times throughout the rising and falling [NO3-] limb for T, pH, DO, SpC, dissolved organic C, Fe (II, III and total), NH4+, and the dissolved gases N2O, CH4, CO2 and H2. Results show slightly lower percent recoveries for nitrate on the falling time/concentration curves at downstream locations, which indicates non-conservative behavior of nitrate. Stable isotope analysis may be needed to distinguish between denitrification and uptake by plants.

PRESENTATION	Emerging Environmental Contaminants and Current Issues	03/02/2006

RICHARDSON, S. D. Emerging Environmental Contaminants and Current Issues. Presented at Alberta Research Council, Edmonton and Vegreville, AB, CANADA, March 02, 2006.
Abstract:	Much has been achieved in the way of environmental protection over the last 30 years. However, as we learn more, new concerns arise. This presentation will discuss emerging environmental contaminants that the U.S. EPA and other agencies are currently concerned about. Emerging contaminants include drinking water disinfection by-products (DBPs), pharmaceuticals, perfluorooctanoic acid (PFOA), polybrominated diphenyl ether (PBDE) flame retardants, and algal toxins. Emerging DBPs include iodo-acids, iodo-trihalomethanes, bromonitromethanes, haloamides, and nitrosamines (including nitrosodimethylamine, NDMA). New toxicological research is revealing that some of these emerging DBPs are more genotoxic and cytotoxic than DBPs that are currently regulated. Moreover, there are new issues with the use of alternative disinfectants (chloramines, ozone, chlorine dioxide), as many of these emerging DBPs are increased in formation with alternative disinfectants, relative to chlorine. Some of the emerging contaminants (e.g., nitrosamines) are currently listed on the Unregulated Contaminants Monitoring Rule (UCMR2), which requires EPA to select five or more contaminants every five years to consider for regulation. Other emerging contaminants are listed on the Contaminant Candidate List (CCL), which identifies drinking water contaminants that might be regulated by EPA at a future date, and other emerging contaminants are currently under consideration for the UCMR or CCL. The status and health/environmental issues with these emerging environmental contaminants will be discussed.

PRESENTATION	The Next Generation of Drinking Water Disinfection By-Products and Health Issues	03/03/2006

RICHARDSON, S. D. The Next Generation of Drinking Water Disinfection By-Products and Health Issues. Presented at Invited Seminar at the University of Alberta, Edmonton, AB, CANADA, March 03, 2006.
Abstract:	Drinking water disinfection by-products (DBPs) are of concern because some epidemiologic studies have shown that some DBPs are associated with cancer or adverse reproductive/developmental effects in human populations, and other studies have shown that certain DBPs cause similar health effects in laboratory animals. As a result, the U.S. EPA has regulated several DBPs. However, more than 500 DBPs have been reported in drinking water for which little or no occurrence and health data exist. In an effort to obtain new information on unregulated DBPs, we initiated a Nationwide Occurrence Study to quantify priority DBPs (those predicted by toxicology experts to have an adverse health effect) to determine how often they occur and at what levels. Various analytical methods, including mass spectrometry, were used to quantify these priority DBPs and identify new ones. An important and unexpected finding of this study was that many of the priority DBPs (e.g., iodo-trihalomethanes, trihalonitromethanes, MX analogs, and dihaloaldehydes) were formed at higher levels with the use of alternative disinfectants (ozone, chloramines, chlorine dioxide) as compared to chlorine. In addition, five iodo-acids were identified for the first time. One of these iodo-acids-- iodoacetic acid--is more genotoxic and cytotoxic than other DBPs currently regulated, and there is information that points to increased iodo-DBP formation with the use of chloramines. A follow-up iodo-DBP occurrence study is currently in progress, where these iodo-acid and iodo-trihalomethane DBPs are being quantified in chloraminated drinking waters across the United States (and one site in Canada). In addition, a new EPA study (the Four Lab Study), which involves the chemical and toxicological evaluation of complex drinking water mixtures treated with chlorine and alternative disinfectants, will be briefly discussed, along with other important new health effects information.

PRESENTATION	Emerging Contaminants in the Environment	04/03/2006

RICHARDSON, S. D. Emerging Contaminants in the Environment. Presented at Tenth International Symposium on Biological and Environmental Reference Materials, Charleston, SC, April 03 - 07, 2006.
Abstract:	Much has been achieved in the way of environmental protection over the last 30 years. However, as we learn more, new concerns arise. This presentation will discuss chemical and microbial contaminants that the U.S. EPA and other agencies are currently concerned about. In this group of contaminants are perfluorooctanoic acid (PFOA), pharmaceuticals, pesticide degradation/reaction products, and polybrominated diphenyl ethers (PBDEs); emerging drinking water pollutants, such as perchlorate, organotins, and algal toxins; new drinking water disinfection by-products (DBPs), such as nitrosodimethylamine (NDMA), iodo-acids, iodo-trihalomethanes, and bromonitromethanes; as well as pathogenic microorganisms like Cryptosporidium, Giardia, Legionella, microsporidia, and Helicobacter pylori. Many of these contaminants have been proposed for consideration under the Unregulated Contaminants Monitoring Rule, which requires EPA to select five or more contaminants every five years to consider for regulation. In 1998, a Contaminant Candidate List was established, which explicitly identifies drinking water contaminants that might be regulated by EPA at a future date. Analytical methods are available for many of the proposed contaminants; however, several contaminants do not have rugged, reliable methods. The status and issues with these chemical contaminants will be discussed.

PRESENTATION	Emerging Environmental Contaminants and Current Issues, Meeting in Seattle, Wa	05/28/2006

RICHARDSON, S. D. Emerging Environmental Contaminants and Current Issues, Meeting in Seattle, Wa. Presented at American Society for Mass Spectrometry Conference, Seattle, WA, May 28 - June 01, 2006.
Abstract:	Much has been achieved in the way of environmental protection over the last 30 years. However, as we learn more, new concerns arise. This presentation will discuss chemical and microbial contaminants that the U.S. EPA and other agencies are currently concerned about. In this group of contaminants are perfluorooctanoic acid (PFOA), pharmaceuticals, pesticide degradation/reaction products, and polybrominated diphenyl ethers (PBDEs); emerging drinking water pollutants, such as perchlorate, organotins, and algal toxins; new drinking water disinfection by-products (DBPs), such as nitrosodimethylamine (NDMA), iodo-acids, iodo-trihalomethanes, and bromonitromethanes; as well as pathogenic microorganisms like Cryptosporidium, Giardia, Legionella, microsporidia, and Helicobacter pylori. Many of these contaminants have been proposed for consideration under the Unregulated Contaminants Monitoring Rule, which requires EPA to select five or more contaminants every five years to consider for regulation. In 1998, a Contaminant Candidate List was established, which explicitly identifies drinking water contaminants that might be regulated by EPA at a future date. Analytical methods are available for many of the proposed contaminants; however, several contaminants do not have rugged, reliable methods. The status and issues with these chemical contaminants will be discussed.

PRESENTATION	Overview of Emerging Contaminants of Concern in Drinking Water	02/09/2006

RICHARDSON, S. D. Overview of Emerging Contaminants of Concern in Drinking Water. Presented at USDA National Water Conference, San Antonio, TX, February 05 - 09, 2006.
Abstract:	Much has been achieved in the way of environmental protection over the last 30 years. However, as we learn more, new concerns arise. This presentation will discuss chemical and microbial contaminants that the U.S. EPA and other agencies are currently concerned about. In this group of contaminants are perfluorooctanoic acid (PFOA), pharmaceuticals, pesticide degradation/reaction products, and polybrominated diphenyl ethers (PBDEs); emerging drinking water pollutants, such as perchlorate, organotins, and algal toxins; new drinking water disinfection by-products (DBPs), such as nitrosodimethylamine (NDMA), iodo-acids, iodo-trihalomethanes, and bromonitromethanes; as well as pathogenic microorganisms like Cryptosporidium, Giardia, Legionella, microsporidia, and Helicobacter pylori. Many of these contaminants have been proposed for consideration under the Unregulated Contaminants Monitoring Rule, which requires EPA to select five or more contaminants every five years to consider for regulation. In 1998, a Contaminant Candidate List was established, which explicitly identifies drinking water contaminants that might be regulated by EPA at a future date. Analytical methods are available for many of the proposed contaminants; however, several contaminants do not have rugged, reliable methods. The status and issues with these chemical contaminants will be discussed.

PRESENTATION	Modeling Processes Controlling Mercury Fate in Watersheds Receiving Atmospheric Deposition Comparison of Field Scale Gleams and Watershed Scale Wcs-Gbmm	08/06/2006

AMBROSE, R. B., I. X. TSIROS, T. A. WOOL, AND T. DAI. Modeling Processes Controlling Mercury Fate in Watersheds Receiving Atmospheric Deposition Comparison of Field Scale Gleams and Watershed Scale Wcs-Gbmm. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	Long-term simulations of mercury fate in watersheds are needed to support regulations such as TMDLs and to predict the effectiveness of regulatory proposals, such as the Clean Air Mercury Rule (CAMR). Scientific uncertainties in mercury fate process descriptions combined with incomplete empirical datasets and gaps in available simulation technology have lead to significant levels of uncertainty in long-term predictions. These issues are investigated in a case study of mercury fate in Brier Creek, Georgia. Atmospheric deposition and soil concentration data were used along with simulation models to calculate mercury build-up and transport through Brier Creek watershed. Two linked models were used to examine watershed-scale terrestrial transport and fate of mercury: the Watershed Characterization System Mercury Tool (WCS) and the Grid-Based Mercury Model (GBMM). The more detailed GLEAMS-Hg was used to examine field-scale transport and fate of mercury, and to better constrain key parameters in the watershed-scale models. Brier Creek watershed was subdivided for the WCS-GBMM simulations. GLEAMS-Hg simulations were run on a set of fields within the watershed representing different land uses. Decadal-scale simulations were used to calibrate the models to recent soil mercury data. Finer scale simulations were run to calculate daily mercury loading under current conditions. Predicted runoff and erosion loadings were compared, and sensitivity analyses were conducted to determine the key parameters and forcing functions controlling long and short-term mercury loading from this watershed. This case study provides a realistic example of the capabilities and limitations of watershed mercury simulations. General spatial loading patterns and trends can be calculated, but specific spatial and temporal details in the simulations are uncertain. While uncertainties could be reduced with more data, better descriptions of mercury transport and fate processes are needed.

PRESENTATION	Investigating Complexity in Food Web Bioaccumulation Modeling Using the Bioaccumulation and Aquatic System Simulator	08/08/2006

BARBER, M. C. AND J. M. JOHNSTON. Investigating Complexity in Food Web Bioaccumulation Modeling Using the Bioaccumulation and Aquatic System Simulator. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	Bioaccumulation of methylmercury in exposed fish communities is primarily mediated via dietary uptake rather than direct gill uptake from the ambient water. Consequently, accurate predication of fish methylmercury concentrations demands reasonably realistic presentations of a community's food web and trophic dynamics. Although many fish bioaccumulation models have characterized fish diets as simple food chains or as static food webs whose dietary proportions are constant, real world food webs and trophic dynamics are much more complex. Fish, for example, often feed opportunistically or selectively on prey items based on their availability. Foraging patterns and strategies of fish also typically follow well-defined relationships with the fish?s age or body size (i.e., length or weight). The size of prey consumed by fish also strongly correlated to its own body size. Each of these relationships, and others, makes characterization of food webs for bioaccumulation modeling a nontrivial challenge. In the work presented here, we use the BASS Bioaccumulation and Aquatic System Simulator to investigate the effects of different dynamic food web structures on methylmercury bioaccumulation in three structurally and regionally different fish communities. Communities analyzed by this research include canal, alligator hole, and marsh fish communities in the Florida Everglades, riverine fish communities of the Shenandoah River Basin, VA, and reservoir fish communities of the Cheyenne River, SD. This research demonstrates that food web complexity does strongly influence simulated methylmercury bioaccumulation in fish. Simulated patterns that are compared to field observations are both species and community dependent. Key parameters influencing simulated bioaccumulation dynamics include elective versus fixed dietary percentages, predator-prey size relationships, and assumed prey switching behavior when nominal prey are unavailable. Other key parameters, that are mediated by the assumed predator-prey size relationships, are the growth rates and recruitments patterns of forage fish within the community of interest.

PRESENTATION	Simulation of Freshwater Plume from Lake Pontchartrain and the Mississippi River in the Wake of Hurricane Katrina	02/22/2006

KHANGAONKAR, T., W. E. FRICK, H. LIU, AND Z. YANG. Simulation of Freshwater Plume from Lake Pontchartrain and the Mississippi River in the Wake of Hurricane Katrina. Presented at 2006 Ocean Sciences Meeting, Honolulu, HI, February 20 - 24, 2006.
Abstract:	In the spirit of a post-Katrina response, a three-dimensional hydrodynamic model was set up and applied to the hurricane Katrina affected region of Mississippi River delta, Lake Pontchartran, and the Gulf of Mexico coastline near New Orleans. Following Katrina, there was concern about dispersion and spreading of bacteria and other contaminants from the CSO mixed streams from de-watering of New Orleans into Lake Pontchartrain, and subsequent flow of the contaminated water out of the Lake into the coastal waters. The objective of this modeling effort was to develop a numerical predictive tool to assess the short term/long-term ecosystem impacts from the outflow of polluted water and re-suspended contaminated sediments from Lake Pontchartrain, on the nearby wetlands along the coastline near the mouth of Mississippi River.

PRESENTATION	The Athens Lab's Role in EPA's Computational Toxicology Program With An Emphasis on Metabolomics as a Diagnostic Tool for Toxicology	02/24/2006

COLLETTE, T. W. The Athens Lab's Role in EPA's Computational Toxicology Program With An Emphasis on Metabolomics as a Diagnostic Tool for Toxicology. Presented at UGA Interdisciplinary Toxicology Program - Staff, Student and Faculty Retreat, Athens, GA, February 24, 2006.
Abstract:	This presentation gives a brief introduction to EPA's computational toxicology program and the Athens Lab's role in it. The talk also covered a brief introduction to metabolomics; advantages/disadvanage of metabolomics for toxicity assessment; goals of the EPA Athens metabolomics group; metabolomics applications underway; and some planned/recently initiated projects.

PRESENTATION	Virtual Beach Using Empirical Models to Predict Recreational Water Quality	01/20/2006

FRICK, W. E. AND Z. GE. Virtual Beach Using Empirical Models to Predict Recreational Water Quality. Presented at NOAA's Ocean and Human Health Initiative All PI's 2006 Annual Meeting, Charleston, SC, January 18 - 20, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Approaches to Ecosystem and Human Exposure to Mercury for Sensitive Populations	09/02/2006

MANGIS, D. R., J. M. JOHNSTON, AND E. M. SUNDERLAND. Approaches to Ecosystem and Human Exposure to Mercury for Sensitive Populations. Presented at International Conference on Environmental Epidemiology and Exposure, Paris, FRANCE, September 02 - 06, 2006.
Abstract:	Both human and ecosystem exposure studies evaluate exposure of sensitive and vulnerable populations. We will discuss how ecosystem exposure modeling studies completed for input into the US Clean Air Mercury Rule (CAMR) to evaluate the response of aquatic ecosystems to changes in mercury deposition will be used to improve human exposure modeling for methylmercury. The ecosystem study completed for CAMR utilizes the mercury models WASP, WCS, BASS, and SERAFM to evaluate depositional change dynamics in five freshwater case studies, forecasting the impacts of mercury reductions to ecosystems and fish tissue concentrations. Results from the five freshwater case studies showed that most freshwater systems will achieve 90% of the benefits of the mercury emissions reductions as the result of CAMR in 2-3 decades. The time lag in ecosystem response has a major effect on the benefits of regulations and how quickly these benefits are translated into human health benefits. By coupling ecosystem process models developed to evaluate the impacts of mercury reductions on sensitive ecosystems with atmospheric source models, and human consumption models, we can improve our human exposure risk analyses of mercury control scenarios, and better evaluate the impacts of local mercury hotspots to ecosystems and local fish consumptive human populations.

PRESENTATION	Integrated Multimedia Decision-Making for Human and Ecological Risk Assessment: A National-Scale Study of Land Application of Arsenic-Bearing Wastes	09/02/2006

BABENDREIER, J. E. Integrated Multimedia Decision-Making for Human and Ecological Risk Assessment: A National-Scale Study of Land Application of Arsenic-Bearing Wastes. Presented at International Conference on Environmental Epidemiology and Exposure, Paris, FRANCE, September 02 - 06, 2006.
Abstract:	Requisite to the development and application of sound waste management policies, decision-makers must discern the impact of a given waste management approach upon both human and ecological receptors. To configure such policies solely upon the assessment of impact to humans, for example, may result in unacceptable risk to ecological receptors. Historically, intuition reflecting the most likely affected community and exposure pathway of concern has guided the focus of risk assessments upon one or the other class of receptors. Presumably, this has been well founded for single-medium assessments in light of relative toxicity for a given contaminant and location of receptors at a given site. For many contaminants though, it is actually the case that significant risks are presented to both receptor classes, expressed through a variety of media/pathway exposures, where significance depends upon a host of decision variables the decision-maker must consider and ultimately set for a given policy (e.g., distance from source, acceptable risk level, and % population protected). In this work, using 3MRA and associated national, regional, and site-based data sets, an assessment of risks to human and ecological receptors is considered for land application of Arsenic-bearing wastes across the conterminous United States.

PRESENTATION	Comparing the Utility of Multimedia Models for Human and Ecological Exposure Analysis: Two Cases	09/02/2006

RECKHOW, K. H., J. E. BABENDREIER, R. T. DI GUILIO, AND D. A. VALLERO. Comparing the Utility of Multimedia Models for Human and Ecological Exposure Analysis: Two Cases. Presented at International Conference on Environmental Epidemiology and Exposure, Paris, FRANCE, September 02 - 06, 2006.
Abstract:	A number of models are available for exposure assessment; however, few are used as tools for both human and ecosystem risks. This discussion will consider two modeling frameworks that have recently been used to support human and ecological decision making. The study will compare and contrast a Bayesian approach for pooling pre-implementation model forecasts with post-implementation measurements to assess compliance with the relevant water quality standard with an integrated multimedia national-scale study of land application of arsenic-bearing wastes (the latter is presented separately at this conference). A specific application of each model will provide a case study. The first case will address the U.S. EPA?s Multimedia, Multipathway, and Multireceptor Risk Assessment (3MRA) model from the standpoint of determining a variety of exposure profiles for receptor classes of concern for land-based arsenic disposal scenarios. This approach will be compared to a Bayesian process for updating model output using subsequent monitoring data. The updated results are a combination of our understanding of the system (reflected in model results) and the information in the data. The Bayesian SPARROW model was used to predict mean and standard deviation of the nitrogen loading as the basis for constructing the prior distribution of the nitrogen concentrations in the Neuse River Basin, North Carolina. The comparison will consist of a judgment by the presenters of the advantages and disadvantages of these model applications for ecological and exposure assessments.

PRESENTATION	Modeling Mercury Behavior in a Contaminated Desert Stream and Constructed Wetland	02/22/2006

BROWN, S., L. SAITO, C. D. KNIGHTES, AND M. GUSTIN. Modeling Mercury Behavior in a Contaminated Desert Stream and Constructed Wetland. Presented at NWRA 2006 Conference, Mesquite, NV, February 21 - 23, 2006.
Abstract:	The Steamboat Creek (SBC) watershed is highly contaminated with mercury and is considered the most polluted tributary of the Truckee River. Restoration is being considered at its confluence with the Truckee River to reduce pollutant loads, but there is concern that restoration could exacerbate mercury loading to the river. In this study, a new mercury model (SERAFM) was applied to provide insight on mercury transformation kinetics in SBC in relation to residence time and season. The steady state, single segment, mass balance model was used to simulate mercury processes in a reach of SBC and a wetland mesocosm. Calibrated mercury transformation rates and sorption coefficients were restricted to documented ranges. The general trend of mercury concentrations were represented by the model with an overall error of 14% and 15% for the reach and mesocosm, respectively, with the greatest error observed when mercury dynamics in the study areas were extreme. The model performed well overall, but some modifications are suggested for modeling western U.S. stream mercury dynamics.

PRESENTATION	Overview of Session Goals With Examples of the Evolution of Multi-Media Modeling for Informing Regulatory Decisions at the U.S. Environmental Protection Agency	08/06/2006

KNIGHTES, C. D. Overview of Session Goals With Examples of the Evolution of Multi-Media Modeling for Informing Regulatory Decisions at the U.S. Environmental Protection Agency. Presented at Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Abstract:	The presence of high concentrations of mercury in fish tissue worldwide has resulted in increased concern of the exposure risks of fish-eating populations. To develop effective regulations and management practices requires a solid quantitative assessment of the entire mercury exposure pathway from source to receptor. This pathway includes anthropogenic emissions, atmospheric deposition, watershed and water body cycling, aquatic bioaccumulation, and consumption by humans. The National Exposure Research Laboratory within the US EPA has been developing a water quality tool kit that incorporates independently developed models with associated linkages to permit modeling of the different requisite compartments for mercury as well as other contaminants. Here, we present the EPA?s development of an integrated linked multi-media modeling framework with examples of its implementation. The specific models within the framework include watershed models (WCS-MLM and GBMM), water body models (WASP7 and SERAFM), and bioaccumulation models (BASS and FGETS). Together, these models have been used for regulatory support, such as TMDL development, and for policy support, such as for the Clean Air Mercury Rule. Case studies of specific applications of these models will be presented in this session, and the challenges in using empirical and modeling science for these model applications will be discussed. Applications of mercury modeling cannot be viewed as predictive a priori; rather each model must be calibrated on a site basis. The lack of available data and understanding of mercury process chemistry limit the robustness and reliability of current modeling forecasts. An overview of the goals of this entire session, including its platform and poster presentations, will be discussed.

PRESENTATION	Perfluorooctanoic Acid (Pfoa) and Perfluorononanoic Acid (Pfna) in Neonatal Mice Following in Utero Exposure to 8-2 Fluorotelomer Alcohol (Ftoh)	06/26/2006

HENDERSON, W. M. Perfluorooctanoic Acid (Pfoa) and Perfluorononanoic Acid (Pfna) in Neonatal Mice Following in Utero Exposure to 8-2 Fluorotelomer Alcohol (Ftoh). Presented at Teratology Society 46th Annual Meeting, Tucson, AZ, June 24 - 29, 2006.
Abstract:	The fluorotelomer alcohols (FTOHs) are the probable precursors of a homologous series of perfluoroalkyl carboxylic acids (PFCAs) detected globally in both mammalian and environmental samples. Recently, 8-2 FTOH has been classified as a xenoestrogen and its derivatives, perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA), have been correlated with developmental toxicity in rats and rabbits. Previous work in our laboratory determined that in mice, fetal concentrations of the terminal metabolites, PFOA and PFNA, increase up to gestation day (GD) 18 following a single oral maternal exposure on GD8. However, maternal serum and liver concentrations gradually decreased having reached peak concentrations by 24 h post-treatment. The purpose of this study was to investigate the neonatal transfer of these stable metabolites following in utero exposure to 8-2 FTOH. In conclusion, exposure of neonates to metabolites of 8-2 FTOH can occur both pre- and postnatally following a single oral maternal dose on GD8.

PRESENTATION	A Risk-Assessment of Landfill Disposal of Wtp-Generated Abrs Using the Integrated Multimedia Modeling System 3mra 1.X	02/13/2006

BABENDREIER, J. E. A Risk-Assessment of Landfill Disposal of Wtp-Generated Abrs Using the Integrated Multimedia Modeling System 3mra 1.X. Presented at Symposium on Disposal of Arsenic-Bearing Water Treatment Residuals, Tucson, AZ, February 13 - 14, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Plume Formation, Transport and Modeling, Presented in Reno, Nevada	03/06/2006

WEAVER, J. W. Plume Formation, Transport and Modeling, Presented in Reno, Nevada. Presented at MTBE and Other Fuel Oxygenates: Comprehensive Site Assessment and Successful Groundwater Remediation Workshop, Reno, NV, March 06 - 07, 2006.
Abstract:	This presentation presents information on plume formation, transport and modeling. The outline for the presentation is: conceptualization of hydrocarbon releases; factors affecting plume length and concentration; modeling considerations; and uncertainty in model calculations.

PRESENTATION	On-Line Tools for Proper Vertical Positioning of Vertical Sampling Intervals During Site Assessment	03/20/2006

WEAVER, J. W. AND V. GOROKHOVSKI. On-Line Tools for Proper Vertical Positioning of Vertical Sampling Intervals During Site Assessment. Presented at 18th Annual National Tanks Conference, Memphis, TN, March 20 - 22, 2006.
Abstract:	This presentation presents on-line tools for proper vertical positioning of vertical sampling intervals during site assessment. Proper vertical sample interval selection is critical for generate data on the vertical distribution of contamination. Without vertical delineation, there is the possibility of underestimating the length of a contaminant plume. Tools are needed to plan proper vertical sampling, because of the expense of characterization. EPA developed an on-line calculator to estimate plume diving that uses estimates of hydraulic conductivity and aquifer recharge to estimate the minimum depth to collect a meaningful sample. This calculator has provided a useful tool for improved site assessment and raised awareness of recharge-driven plume diving. The method is limited, however, by the need to estimate the recharge rate, a parameter that is difficult to estimate in practice. Consequently, the resulting plume diving calculation results might be too uncertain for practical use. To avoid this problem, modifications to the procedure have been developed. Here the model fits the solution to water levels to avoid the need to estimate recharge rates. Additional work to overcome limitations in the methodology involves numerical solution for sloping aquifer bottoms.

PRESENTATION	Occurrence and Toxicity of Iodo-Acid and Iodo-Thm DBPs in Chloraminated Drinking Water	03/17/2006

RICHARDSON, S. D., F. G. CRUMLEY, J. J. ELLINGTON, J. J. EVANS, B. C. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, AND E. D. WAGNER. Occurrence and Toxicity of Iodo-Acid and Iodo-Thm DBPs in Chloraminated Drinking Water. Presented at Safe Drinking Water Symposium, Chapel Hill, NC, March 17, 2006.
Abstract:	As part of a recent Nationwide Disinfection By-Product (DBP) Occurrence Study, iodo-acids were identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid, bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. They were identified in drinking water samples from a plant using chloramination for disinfection. Gas chromatography (GC) with low and high resolution electron ionization (EI)-mass spectrometry (MS) was used to identify them. These identifications have since been confirmed using authentic chemical standards, both commercial (for iodoacetic acid) and synthesized (for the other four iodo-acids). There is concern about these new iodo-acid DBPs because mammalian cell cytotoxicity and genotoxicity studies have revealed that iodoacetic acid is highly cytotoxic and genotoxic, with a genotoxicity potency 2X higher than bromoacetic acid, the most genotoxic of the regulated haloacetic acids. Also, many drinking water treatment plants in the United States have switched from chlorine to chloramines for treatment. New evidence indicates that the formation of iodinated DBPs will be higher in chloraminated drinking water than in chlorinated drinking water. The goal of this work was to develop an analytical method to quantify these five iodo-acids in drinking water, measure their occurrence in several drinking waters treated with chloramination, determine whether they are maximized in waters treated with chloramines only (compared to chlorine and chlorine-chloramines), and investigate the mammalian cell cytotoxicity and genotoxicity of the four synthesized iodo-acids (beyond iodoacetic acid). In addition, two iodo-trihalomethanes (THMs) - dichloroiodomethane and bromochloroiodomethane - were also measured in this study for comparison purposes to the iodo-acids and to determine whether they are also increased in formation by chloramination.

PRESENTATION	Modeling for Environmental Decision Making	03/14/2006

WEAVER, J. W. Modeling for Environmental Decision Making. Presented at The Model Management Course, Stony Brook, NY, March 14, 2006.
Abstract:	This presentation describes the role of models in environmental decision making. An outline of the presentation is the role of models in decision support; the modeling process, past and current; assumptions and limitations; and examples of models.

PRESENTATION	Evaluation of Uncertainty in the J&e Model	03/15/2006

WEAVER, J. W. AND F. TILLMAN. Evaluation of Uncertainty in the J&e Model. Presented at 16th Annual AEHS Meeting and West Coast Conference on Soils, Sediments, and Water, San Diego, CA, March 13 - 16, 2006.
Abstract:	This presentation presents an evaluation of uncertainty in the J&E model. The outline for the presentation is: general commentary on modeling; uncertainty analysis on J&E model; uncertainty reduction analysis; generic best/worst case determination; and correlation of soil and building air flows.

PRESENTATION	EPA on-Line Calculators for Site Assessment Calculations	03/15/2006

WEAVER, J. W. EPA on-Line Calculators for Site Assessment Calculations. Presented at 16th Annual AEHS Meeting and West Coast Conference on Soils, Sediments, and Water, San Diego, CA, March 13 - 16, 2006.
Abstract:	This presentation presents information on the EPA on-line calculators for site assessment calculations which are located on the website www.epa.gov/athens/onsite.

PRESENTATION	Gasoline Composition in the US (1976-2005)	03/20/2006

WEAVER, J. W., L. M. PRIETO, AND L. R. EXUM. Gasoline Composition in the US (1976-2005). Presented at 18th Annual National Tanks Conference, Memphis, TN, March 20 - 22, 2006.
Abstract:	Gasoline composition data are collected by EPA for Clean Air Act compliance requirements, by industry for various purposes and, recently, by EPA/ORD for a compositional study (Weaver et al., 2005, EPA/600/R-05/032, http://www.epa.gov/athens). Each of these data sets are potentially valuable for evaluation of potential environmental impacts from gasoline and impacts on remediation. This part of the study uses thirty years? of industry data from approximately 175 cities, and shows the trends in lead, vapor pressure, benzene, ethers and alcohols. Samples are collected and analyzed by a voluntary industry consortium, currently organized by Northop Grumman Corp in Bartlesville, Oklahoma (http://pps.ms.northropgrumman.com/default.htm). The interpretation of data from these studies requires an understanding of federal and state regulations on fuel composition. Multiple sources of information on these programs were used to develop reliable, up-to-date maps showing gasoline requirements imposed by various regulations. In addition to the insights provided by these comparison of data for cities under differing regulatory requirements, models of each city?s composition are been developed. These will provide a means to estimate release composition given an estimated release data. This information is anticipated to be useful for site assessment and modeling of sites.

PRESENTATION	Estimating and Projecting Impervious Cover in the Southeastern United States	03/20/2006

EXUM, L. R., S. L. BIRD, J. HARRISON, AND C. PERKINS. Estimating and Projecting Impervious Cover in the Southeastern United States. Presented at 18th Annual National Tanks Conference, Memphis, TN, March 20 - 22, 2006.
Abstract:	Urban/suburban land constitutes the fastest growing land use class in the Southeastern United States. Predominant development practices increase impervious surface--areas preventing infiltration of water into the underlying soil. Uncontrolled increase of impervious areas (roads, buildings, parking) can cause detrimental hydrologic changes, stream channel erosion, habitat degradation and severe impairment of aquatic communities. Development practices that reduce impervious area and include preventative strategies to protect water quality are more effective and less costly than remedial restoration efforts. The extensive hydrological alteration of watersheds associated with increased impervious cover is very difficult to control and correct. Complete identification and eventual prevention of urban water quality problems pose significant monitoring, smart growth and water quality management challenges. Simple and reliable methods to estimate and project impervious cover can help identify areas where a watershed is at risk of changing rapidly from a system with relatively pristine streams to one with significant symptoms of degradation. We provide a multiple data source (MDS) estimation of imperviousness in the Southeastern U.S. In this study, a method for estimating and projecting impervious cover for 12/14 digit hydrologic units over a large area was developed and tested. These methods were applied throughout EPA Region 4's eight southeastern states to provide a screening tool to guide monitoring and educational efforts. These estimates demonstrate an inexpensive method to determine impervious cover with known accuracy at the watershed and sub-watershed scales, and characterize imperviousness changes over time. Additionally, this report estimates future impervious cover in the Southeastern U.S. using the MDS technique. These estimates can guide in-situ monitoring to confirm problems, aid listing of impaired waters under Section 303(d) of the Clean Water Act and total maximum daily load(TMDL) development, provide reliable information to enable sound local planning and land-use decisions, and promote protection and restoration of urban streams.

PRESENTATION	Mapping Gasoline Requirements, Applicable Regulations and Bans	03/22/2006

EXUM, L. R., J. W. WEAVER, AND L. M. PRIETO. Mapping Gasoline Requirements, Applicable Regulations and Bans. Presented at Annual MTBE Meeting, Association of State and Territorial Solid Waste Management Officials, Memphis, TN, March 22, 2006.
Abstract:	Federal and State regulations play an important role in understanding gasoline composition around the United States. Multiple sources of information on these programs were used to develop reliable, up-to-date maps showing gasoline requirements imposed by various regulations. The sources of information included the U.S. Environmental Protection Agency?s Offices of Transportation and Air Quality (OTAQ) and Underground Storage Tanks (OUST), the Department of Energy's Energy Information Administration, the American Petroleum Institute and the National Petroleum Refiner?s Association. To enhance understanding of the various requirements separate maps were made for: (1) Reformulated Gasoline (RFG)/Conventional Gasoline (CG) including mandatory, opt-in and opt-out areas, (2) current and past Winter Oxygenated Fuel Requirements Program, (3) Summer Reid Vapor Pressure Standards, (4) current state bans for methyl tertiary-butyl ether (MTBE), and (5) refinery locations around the U.S, and (6) locations included in EPA/ORD gasoline studies. The presentation will overview the scope of requirements around the U.S.

PRESENTATION	Subsurface Soil Conditions Beneath and Near Buildings and the Potential Effects on Soil Vapor Intrusion	03/22/2006

TILLMAN, F. AND J. W. WEAVER. Subsurface Soil Conditions Beneath and Near Buildings and the Potential Effects on Soil Vapor Intrusion. Presented at 18th Annual National Tanks Conference, Memphis, TN, March 20 - 22, 2006.
Abstract:	Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion. Volatile organic chemicals in contaminated soils or groundwater can emit vapors that may migrate through subsurface soils and enter indoor air spaces of overlying buildings. The evaluation of contaminated sites for the potential for soil vapor intrusion routinely uses a 1-dimensional screening-level model known as the Johnson and Ettinger model. Unsaturated zone moisture content may vary between locations beneath a structure and outside the footprint of the building slab. These differences may have a large effect on vapor-phase transport in the unsaturated zone and vapor intrusion of soil gas into overlying buildings. Continued drying of sub-slab soils will provide increased pathways for vapor transport directly beneath a building. Sub-slab locations near the edge of a structure appear to respond to rainfall at land surface. Subsequently, vapor intrusion risk assessments based on outside-of-slab moisture content values may not be protective of exposures to organic vapors transported from below a building slab.

PRESENTATION	Estimation of Physical Properties and Chemical Reactivity Parameters of Organic Compounds	04/03/2006

HILAL, S. H. AND L. A. CARREIRA. Estimation of Physical Properties and Chemical Reactivity Parameters of Organic Compounds. Presented at 2nd Knoxville Workshop on Reactive Toxicity, Knoxville, TN, April 01 - 04, 2006.
Abstract:	The computer program SPARC (Sparc Performs Automated Reasoning in Chemistry)has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC uses computational algorithms based on fundamental chemical structure theory to estimate a variety of reactivity parameters. Resonance models were developed/calibrated on more than 5000 light absorption spectra, whereas electrostatic interaction models were developed using more than 4500 ionization pKas in water. Solvation models (i.e., dispersion, induction, etc.) have been developed using more than 10000 physical property data points on properties such as vapor pressure, boiling point, solubility, activity coefficient, Henry's constant, GC retention times, Kow, etc. At the present time, SPARC predicts chemical reactivity parameters such as gas phase electron affinity, ionization pKa, ester hydrolysis rate constant, Delta H formation, E(1/2) reduction potential and numerous physical properties of organic compounds from molecular structure. Modeling the Michael addition reactions through SPARC will be discussed at this meeting.

PRESENTATION	Gasoline Composition in the United States (1976-2005)	04/04/2006

WEAVER, J. W., L. M. PRIETO, AND L. R. EXUM. Gasoline Composition in the United States (1976-2005). Presented at EPA Region 3 LUST Conference, Roanoke, VA, April 03 - 05, 2006.
Abstract:	Gasoline composition data are collected by EPA for Clean Air Act compliance requirements, by industry for various purposes and, recently, by EPA/ORD for a compositional study (Weaver et al., 2005, EPA/600/R-05/032, http://www.epa.gov/athens). Each of these data sets are potentially valuable for evaluation of potential environmental impacts from gasoline and impacts on remediation. This part of the study uses thirty years' of industry data from approximately 175 cities, and shows the trends in lead, vapor pressure, benzene, ethers and alcohols. Samples are collected and analyzed by a voluntary industry consortium, currently organized by Northop Grumman Corp in Bartlesville, Oklahoma (http://pps.ms.northropgrumman.com/default.htm). The interpretation of data from these studies requires an understanding of federal and state regulations on fuel composition. Multiple sources of information on these programs were used to develop reliable, up-to-date maps showing gasoline requirements imposed by various regulations. In addition to the insights provided by these comparison of data for cities under differing regulatory requirements, models of each city's composition are been developed. These will provide a means to estimate release composition given an estimated release data. This information is anticipated to be useful for site assessment and modeling of sites.

PRESENTATION	Assessment of Plume Diving	04/05/2006

NICHOLS, E. AND J. W. WEAVER. Assessment of Plume Diving. Presented at EPA Region 3 LUST Conference, Roanoke, VA, April 03 - 05, 2006.
Abstract:	This presentation presents an assessment of plume diving. Observations included: vertical plume delineation at East Patchogue, NY showed BTEX and MTBE plumes sinking on either side of a gravel pit; Lake Druid TCE plume sank beneath unlined drainage ditch; and aquifer recharge/discharge areas drive ground water flow. Also presented were methods to assess potential for and magnitude of diving plumes using: analytical and numerical models; field characterization techniques; and geochemical assessment.

PRESENTATION	Emerging Drinking Water Disinfection By-Products and Health Issues	04/12/2006

RICHARDSON, S. D. Emerging Drinking Water Disinfection By-Products and Health Issues. Presented at Invited Seminar at the University of Illinois, Urbana, IL, April 12 - 16, 2006.
Abstract:	This presentation presents emerging disinfection by-products and potential health effects; results from the Four Lab Study; and toxicity-based identification work (addressing >50% TOX in high molecular weight fraction).

PRESENTATION	Entrainment Models	03/29/2006

FRICK, W. E. Entrainment Models. Presented at Invited Lecture at the Georgia Insitute of Technology, Atlanta, GA, March 29, 2006.
Abstract:	This presentation presented information on entrainment models. Entrainment models use entrainment hypotheses to express the continuity equation. The advantage is that plume boundaries are known. A major disadvantage is that the problems that can be solved are rather simple. The purpose of this presentation is to argue that simple entrainment models can help to refine complex fluid dynamics models.

PRESENTATION	Effects of Watershed Disturbance on Small Streams	04/03/2006

BURKE, R. A. Effects of Watershed Disturbance on Small Streams. Presented at Gerogia College and State University Environmental Club, Milledgeville, GA, April 03, 2006.
Abstract:	This presentation presents the effects of watershed disturbance on small streams. The South Fork Broad River Watershed was studied to evaluate the use of landscape indicators to predict pollutant loading at small spatial scales and to develop indicators of pollutants. Also studied was Robinson Forest, Kentucky. This area was selected for the mountaintop mining/valley fill impacts on streams. Visual observation and available data indicates dramatic impact on stream condition.

PRESENTATION	Watershed Restoration and Fisheries Management in the Mid-Atlantic Highlands	04/11/2006

BARBER, M. C., M. J. CYTERSKI, J. M. JOHNSTON, Y. M. MOHAMOUD, B. RASHLEIGH, R. S. PARMAR, AND K. L. WOLFE. Watershed Restoration and Fisheries Management in the Mid-Atlantic Highlands. Presented at EPA Region III Fish Database and Tools Summit, Berkeley Springs, WV, April 11, 2006.
Abstract:	This presentation is about watershed restoration and fisheries management in the Mid-Atlantic Highlands. The goal of the Canaan Valley Institue is to develop and implement solutions to restore damaged areas and protect aquatic systems in the Mid-Atlantic Highlands. A decision analysis software system, WHAT-IF (Watershed Health Assessment Toolkit - Investigating Fisheries) is presented. This system will assist with watershed management and restoration strategies.

PRESENTATION	Enantiomer-Specific Fate and Effects of Modern Chiral Pesticides	03/28/2006

GARRISON, A. W. Enantiomer-Specific Fate and Effects of Modern Chiral Pesticides. Presented at Workshop on Chiral Xeniobiotics, Birmingham, UK, March 28, 2006.
Abstract:	This slide presentation presents enantiomer-specific fate and effects of modern chiral pesticides. The research areas presented were analytical separation of enantiomers; environmental occurrence of enantiomers; transformation rates and enantioselectivity; bioaccumulation; and enantioselectivity effects. Conclusions of the presentation were many modern pesticides are chiral; capillary electrophoresis is useful for laboratory studies of pesticide transformation; microbial transformation is usually observed to be enantioselective, but it is not possible at this time to predict the direction or extent of selectivity in a different environment; and enantiomers usually differ in their effects, including toxicity and ED activity, but little definitive work has been done with pesticides; metabonomics, proteomics and other modern molecular biochemistry techniques are applicable to investigate toxicity mechanisms; accurate risk assessment requires investigation of the fate and effects of each enantiomer of a chiral pesticide; and the ultimate goal of this research is to show whether the manufacture and use of single-enantiomer pesticides is of benefit to the environment.

PRESENTATION	Aerobic Denitrification: Implications for the Mom River Basin	05/16/2006

THOMAS, R., J. W. WASHINGTON, AND L. SAMARKINA. Aerobic Denitrification: Implications for the Mom River Basin. Presented at EPA Science Forum, Washington, DC, May 16 - 18, 2006.
Abstract:	Each year about 1.6 million metric tons of nitrogen, mostly from agriculture, is discharged from the lower Mississippi/Atchafalaya River Basin into the Gulf of Mexico, and each spring this excess nitrogen fuels the formation of a huge hypoxic zone in the Gulf. In the Mississippi, as well as most nitrogen-degraded rivers and streams, NO(3-) is the dominant N species and therefore understanding its biogeochemical behavior is critical for accurate nitrogen fate modeling. Based on thermodynamic modeling of data representing samples from natural freshwater systems, dissolved O(2) and NO(3-) were reduced to nearly equal redox potentials in every sample we analyzed, suggesting simultaneous reduction of O2 and NO(3-). In an effort to evaluate implications of these thermodynamic data experimentally, five headspace-recirculating microcosm reactors were constructed using engineered glass jars, copper tubing, and a peristaltic pump. An O(2) saturated, sterile synthetic river water solution (0.13 mM NO(3)) was added to the reactors aseptically along with three different inoculums taken from (1) natural river water, (2) wetland surface water, and (3) wetland sediment slurry. Two sterile controls were also employed. The reactors were sealed and headspace gas, originally of atmospheric composition, was recirculated through the solution. Within approximately three weeks, the N(2)O concentration in the headspace increased greater than five fold, while the nitrate concentration in the slurry decreased concomitantly. At the end of the experiment, the dissolved O(2) concentration in the slurry was approximately that of water equilibrated with atmospheric O(2). Although aerobic denitrification recently has been shown to take place under non-environmental conditions such as sewage treatment facilities where NO(3-) and C(org) are very concentrated, to our knowledge this is the first work to report aerobic denitrification under conditions typically found in environmental settings, such as the Mississippi River Basin. Our discovery of aerobic denitrification is expected to have a high impact on N-fate modeling as most existing models call for denitrification to take place in anoxic settings, yet most impacted surface waters are aerobic.

PRESENTATION	Metabolomics for Developing Markers of Chemical Exposure and Distinguishing Toxicity Pathways	05/16/2006

WHITEHEAD, T. L., T. W. COLLETTE, D. R. EKMAN, A. W. GARRISON, J. F. KENNEKE, AND Q. TENG. Metabolomics for Developing Markers of Chemical Exposure and Distinguishing Toxicity Pathways. Presented at EPA Science Forum, Washington, DC, May 16 - 18, 2006.
Abstract:	Metabolomics involves the application of advanced analytical and statistical tools to profile changes in levels of endogenous metabolites in tissues and biofluids resulting from disease onset, stress, or chemical exposure. Nuclear Magnetic Resonance (NMR) spectroscopy-based metabolomics has proven useful in mammalian systems for distinguishing between sites and mechanisms of toxicity for tissue-specific toxins. Metabolomics has been characterized as the true measure of metabolic outcomes suggested by changes in gene and protein expression; as such, metabolomics provides a connection between these molecular endpoints and whole organism responses. Although used mostly in mammalian studies, metabolomics is now finding utility in a wide variety of other organisms including aquatic species. We have developed a research program in metabolomics that involves numerous partners across EPA, other federal labs, academia, and the private sector. Our goals are to: 1) develop metabolite-based markers that can be used by EPA in chemical exposure assessments and 2) develop and test hypotheses about toxicity pathways for risk assessments. We are focusing this program on ecologically relevant species - in particular, small fish toxicological models. For example, to better understand the mode-of-action of endocrine-disrupting chemicals (EDCs) in small fish (fathead minnow, zebrafish), we are conducting metabolomic analyses with multiple tissues (brain, blood, liver, and gonad) and urine. Initial metabolomic studies were focused on collection of baseline data for actively-spawning male and female fathead minnows. Subsequent work is focusing on animals exposed to potent EDCs, such as the steroid 17 alpha-ethinylestradiol (EE2). We are developing hypotheses about which tissue- and biofluid-specific metabolite changes will be definitively related to exposure, based on the current understanding of modes-of-action for these chemicals. Results will allow testing of these hypotheses to refine understanding of activity, and will help ensure that molecular markers of EDC exposure, another outcome of this research, are meaningful. While certain metabolites are being specifically targeted in these studies, we will also discern changes in the complete metabolic profile using NMR spectroscopic data with statistical approaches that allow capturing subtle changes in less-abundant metabolites. These data will be integrated with genomic, proteomic, and whole organism data from untreated fish and those exposed to known EDCs.

PRESENTATION	An Integrative Watershed Modeling Framework (Iwmf) for Ecosystem Sustainability Assessment at the Watershed Scale	05/16/2006

MOHAMOUD, Y. M. An Integrative Watershed Modeling Framework (Iwmf) for Ecosystem Sustainability Assessment at the Watershed Scale. Presented at EPA Science Forum, Washington, DC, May 16 - 18, 2006.
Abstract:	The public's right to continued access and use of ecosystem services requires an evaluation of the environmental risks that are associated with activities such as urban development, agriculture, forestry, mining, water withdrawal, and dam construction. Human activities can cause hydrological alterations and other stressors that occur over time, interact with one another resulting in combined and cumulative environmental effects on the ecosystem. Assessing the combined environmental effects of human activities, such as urban development and dam construction, on downstream water availability, quality and demand and on channel morphology and biological integrity of aquatic ecosystems is a major challenge that affects the application of established assessment protocols such as the Total Maximum Daily Load (TMDL) development process. One way to address the combined and the cumulative environmental effects of urban development and water resources development jointly is to use comprehensive watershed models that can simulate the interactions between multiple stressors. Many watershed models and modeling approaches are not adequately comprehensive and do not address changes in water availability resulting from reduced baseflow due to increased impervious cover or increased water withdrawal. This study presents a modeling approach or framework which would allow resource managers and decision makers to link upstream development activities, particularly urban development and water resources development, to downstream environmental effects. The proposed integrative watershed modeling framework (IWMF) is an iterative and adaptive watershed modeling approach that is suitable for evaluating combined environmental effects associated with different land and water development scenarios and for selection of specific development alternatives leading to sustainable use of ecosystem services. The proposed framework is based on the Hydrological Simulation Program- FORTRAN (HSPF) and has three main components: water availability (hydrological alterations), water quality (water quality alterations) and water demand (water allocation) simulation models.

PRESENTATION	Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Chloraminated Drinking Water	05/16/2006

RICHARDSON, S. D., J. J. ELLINGTON, F. G. CRUMLEY, J. J. EVANS, B. C. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, AND E. D. WAGNER. Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Chloraminated Drinking Water. Presented at EPA Science Forum, Washington, DC, May 16 - 18, 2006.
Abstract:	As part of a recent Nationwide Disinfection By-Product (DBP) Occurrence Study, iodo-acids were identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid, bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. These identifications have since been confirmed using authentic chemical standards, both commercial (for iodoacetic acid) and synthesized (for the other four iodo-acids). There is concern about these new iodo-acid DBPs because mammalian cell cytotoxicity and genotoxicity studies have revealed that iodoacetic acid is highly cytotoxic and genotoxic, with a genotoxicity potency 2X higher than bromoacetic acid, the most genotoxic of the regulated haloacetic acids. Also, many drinking water treatment plants in the United States have switched from chlorine to chloramines for treatment. New evidence indicates that the formation of iodinated DBPs will be higher in chloraminated drinking water than in chlorinated drinking water. The goal of this work was to develop an analytical method to quantify these five iodo-acids in drinking water, measure their occurrence in several drinking waters treated with chloramination, determine whether they are maximized in waters treated with chloramines only (compared to chlorine and chlorine-chloramines), and investigate the mammalian cell cytotoxicity and genotoxicity of the four synthesized iodo-acids (beyond iodoacetic acid). Two iodinated trihalomethanes (iodo-THMs), dichloroiodomethane and bromochloroiodomethane, were also measured in these waters. These iodo-THMs were the most commonly found iodo-THMs in the previous Nationwide DBP Occurrence Study. An analytical method similar to EPA Method 552.3 (developed for chlorinated and brominated acetic acids) was developed to extract and quantify iodo-acid concentrations in drinking water samples. The first method applied used tert-amyl methyl ether (TAME) for liquid-liquid extraction (after acidifying the water samples) and sulfuric acid/methanol for derivatization. Later, recoveries were improved by using ethyl acetate for extraction and salting out with sodium sulfate prior to extraction. Gas chromatography/mass spectrometry (GC/MS) with negative chemical ionization (NCI)-MS (and selected ion monitoring) was found to offer the lowest detection limits of the detection techniques investigated (low and sub-ng/L for a 1 L water sample). Analyses were carried out using an Agilent 6890 GC coupled to a 5973 MSD mass spectrometer. Iodo-THMs were extracted using solid phase microextraction (SPME) and were analyzed using GC with high resolution electron ionization (EI)-MS and stable isotope dilution (deuterated standards of each analyte). Two samplings have been conducted to-date on drinking water plants using chloramination for disinfection. The first sampling took place in May 2005 (of five plants), and the second sampling took place in the fall of 2005 (21 plants). Iodoacetic acid and bromoiodoacetic acid were found in most of the plants sampled, at sub-ppb to low-ppb levels. (E)-2-iodo-3-methylbutenedioic acid was also found in many of the plants, and (E)-3-bromo-3-iodo-propenoic acid and (Z)-3-bromo-3-iodo-propenoic acid were found in a few of the plants sampled at sub-ppb levels. The two iodo-THMs sampled, dichloroiodomethane and bromochloroiodomethane, were found at all plants sampled, at low ppb or sub-ppb levels (with a high of 10.2 ppb for bromochloroiodomethane).

PRESENTATION	Development of the Virtual Beach Model, Phase 1: An Empirical Model	05/16/2006

GE, Z. AND W. E. FRICK. Development of the Virtual Beach Model, Phase 1: An Empirical Model. Presented at EPA Science Forum, Washington, DC, May 16 - 18, 2006.
Abstract:	With increasing attention focused on the use of multiple linear regression (MLR) modeling of beach fecal bacteria concentration, the validity of the entire statistical process should be carefully evaluated to assure satisfactory predictions. This work aims to identify pitfalls and misunderstandings of the statistical aspect of modeling. The importance of preliminary inspection of raw data, useful transformations, development of interaction terms, adjustment for time-series effects, identification of outliers, correlation studies, and model selection criteria are stressed. It is recommended the model selection process should be conducted using R2 and Cp statistic as joint criteria. The methodology is illustrated with real data of Huntington Beach, OH, in 2001. Dynamic modeling, as a new concept, is advanced for prediction purpose, as beach bacteria MLR models are in fact beach specific and time varying. This work also serves as a statistical basis for US EPA's public domain pathogen assessment software, Virtual Beach.

PRESENTATION	Nanoscale Biosensors in Ecosystem Exposure Research	03/20/2006

ZEPP, R. G. Nanoscale Biosensors in Ecosystem Exposure Research. Presented at Workshop on Nanosensors and Nanomaterials for Sensors in Ecosystems Research, Research Triangle Park, NC, March 20, 2006.
Abstract:	This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nanowire or carbon nanotubes for sensing of microorganisms; environmental detection of harmful bacteria; and possible limitations to environmental applications.

PRESENTATION	Research Programs at the Ecosystems Research Division, U.S. Environmental Protection Agency	04/20/2006

WEST, C. C. Research Programs at the Ecosystems Research Division, U.S. Environmental Protection Agency. Presented at Chemistry Club at the University of Georgia, Athens, GA, April 20, 2006.
Abstract:	This presentation presents information on the research programs at the Ecosystems Research Division (ERD) of the U.S. Environmental Protection Agency located in Athens, Georgia. The presentation gives an overview of the Agency, laws and regulations that the Agency operates under, the Office of Research and Development's mission and how research is done at ERD.

PRESENTATION	Enhancing Hspf Model Channel Hydraulic Representation	11/06/2006

MOHAMOUD, Y. M. Enhancing Hspf Model Channel Hydraulic Representation. Presented at American Water Resources Association Annual Water Resources Conference, Baltimore, MD, November 06 - 09, 2006.
Abstract:	The Hydrological Simulation Program - FORTRAN (HSPF) is a comprehensive watershed model, which employs depth-area-volume-flow relationships known as hydraulic function table (FTABLE) to represent stream channel cross-sections and reservoirs. An accurate FTABLE determination for a stream cross-section site requires an accurate determination of mean flow depth, mean flow width, roughness coefficient, longitudinal bed slope, and length of the stream reach. A method that uses regional regression equations to estimate mean flow depth, mean flow width, and roughness coefficient is presented. Comparisons of FTABLES generated by the proposed method (alternative method) and FTABLES generated by the BASINS method were made. The alternative method is considered as an enhancement over the BASINS method. First, the alternative method employs a spatially variable roughness coefficient whereas the BASINS method employs an arbitrarily selected spatially uniform roughness coefficient. Second, the alternative method uses mean flow width and mean flow depth estimated from regional regression equations whereas the BASINS method uses mean flow width and depth extracted from the National Hydrography Dataset (NHD). Third, the alternative method offers users the option to use separate roughness coefficients for the in-channel and the floodplain sections of compound channels. Fourth, the alternative method has higher resolution in the sense that area, volume, and flow data are calculated at smaller depth intervals than the BASINS method. To test whether the alternative method enhances channel hydraulic representation over the BASINS method, comparisons of observed and simulated streamflow, flow velocity, and suspended sediment were made for four test watersheds. The results of the comparisons show that the method used to estimate the FTABLE has little influence on hydrologic calibration whereas it has great influence on hydraulic and sediment calibration. The hydrologic calibration results show that observed and simulated daily streamflow comparisons had Nash-Sutcliffe efficiencies that ranged from 0.50 to 0.61 and monthly comparisons had efficiencies that ranged from 0.61 to 0.84. Comparisons of observed and simulated suspended sediments had model efficiencies that ranged from -0.13 to 0.56 for the daily and 0.26 and 0.70 for the monthly comparisons. The overall results of the hydrological, hydraulic, and sediment comparisons show that the alternative method determines a relatively more accurate FTABLE than the BASINS method. We conclude that hydraulic calibration enhances sediment simulation performance, but further improvement in sediment calibration can only be achieved only when hydrological simulation performance is improved with the use of representative precipitation data that has the correct temporal and spatial distribution over the watershed.

PRESENTATION	Seminar in Buffalo, Ny: the Next Generation of Drinking Water Disinfection By-Products and Health Issues	04/28/2006

RICHARDSON, S. D. Seminar in Buffalo, Ny: the Next Generation of Drinking Water Disinfection By-Products and Health Issues. Presented at Invited Seminar at the State University of New York, Buffalo, NY, April 28, 2006.
Abstract:	This powerpoint presentation covered drinking water emerging disinfection by-products and potential health effects; the Nationwide Four Lab Study; and toxicity-based identification work.

PRESENTATION	Simulating Lake Pontchartrain and Mississippi River Outflow After Hurricane Katrina	06/22/2006

FRICK, W. E., T. KHANGAONKAR, H. LIU, AND Z. YANG. Simulating Lake Pontchartrain and Mississippi River Outflow After Hurricane Katrina. Presented at Air & Waste Management Association's 99th Annual Conference and Exhibition, New Orleans, LA, June 20 - 23, 2006.
Abstract:	Hurricane Katrina was the direct cause of the flooding of New Orleans in September 2005. Between its passage and the pumping of flood waters back into Lake Pontchartrain and the Mississippi River, the flood waters acquired considerable amounts of contaminants, notably silver, but also bacteria and other pollutants. As pumping commenced there was concern about the transport of these contaminants from the mixed outfall streams into Lake Pontchartrain and the Mississippi River, and subsequent flow of the contaminated water out of the lake into Mississippi Sound and other coastal waters. The objective of this modeling effort was to develop a numerical predictive tool that could predict the transport and fate of pollutants. Such a capability could be helpful in assessing the short and long-term ecosystem impacts from the outflow of polluted water and re-suspended contaminated sediments from Lake Pontchartrain on the nearby wetlands along the coastline near the mouth of Mississippi River. The model used was Finite Volume Coastal Ocean Model (FVCOM) using available input data.

PRESENTATION	Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Drinking Water	06/04/2006

RICHARDSON, S. D., J. J. ELLINGTON, F. G. CRUMLEY, J. J. EVANS, E. D. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, AND E. D. WAGNER. Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Drinking Water. Presented at 34th International Symposium on Environmental Analytical Chemistry, Hamburg, GERMANY, June 04 - 08, 2006.
Abstract:	As part of a recent Nationwide Disinfection By-product (DBP) Occurrence Study, iodo-acids were identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid, bromoiodoacetic acid, (E)-3-bromo-3-iodo- propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. There is concern about these new iodo-acid DBPs because mammalian cell cytotoxicity and genotoxicity studies have revealed that iodoacetic acid is highly cytotoxic and genotoxic, with a genotoxicity potency 2X higher than bromoacetic acid, the most genotoxic of the regulated haloacetic acids. Also, many drinking water treatment plants in the United States have switched from chlorine to chloramines for treatment. New evidence indicates that the formation of iodinated DBPs will be higher in chloraminated drinking water than in chlorinated drinking water. The goal of this work was to develop an analytical method to quantify these five iodo- acids in drinking water and measure their occurrence in drinking waters treated with chloramination. Two iodinated trihalomethanes(iodo-THMs), dichloroiodomethane and bromochloroiodomethane, were also measured in these waters. These iodo-THMs were the most commonly found iodo-THMs in the previous Nationwide DBP Occurrence Study. An analytical method similar to EPA Method 552.3 (developed for chlorinated and brominated acetic acids) was developed to extract and quantify iodo-acid concentrations in drinking water samples. Gas chromatography/mass spectrometry (GC/MS) with negative chemical ionization (NCI)-MS offered low detection limits (low and sub-ngL). Iodo-THMs were extracted using solid phase microextraction (SPME) and were analyzed using GC with high resolution electron ionization (EI)-MS and stable isotope dilution (deuterated standards of each analyte). Two samplings have been conducted to-date on drinking water plants using chloramination for disinfection. The first sampling took place in May 2005 (of five plants), and the second sampling took place in the fall of 2005 (21 plants). Iodoacetic acid and bromoiodoacetic acid were found in most of the plants sampled, at sub-ppb to low-ppb levels. (E)-2-iodo-3- methylbutenedioic acid was also found in many of the plants, and (E)-3-bromo-3-iodo-propenoic acid and (Z)-3-bromo-3-iodo-propenoic acid were found in a few of the plants sampled at sub-ppb levels. The two iodo-THMs sampled, dichloroiodomethane and bromochloroiodomethane, were found at all plants sampled, at low ppb or sub-ppb levels (with a high of 10.2 ppb for bromochloroiodomethane).

PRESENTATION	EPA Modeling Tools for Wellhead Protection	05/08/2006

KRAEMER, S. R. EPA Modeling Tools for Wellhead Protection. Presented at 5th National Monitoring Conference, San Jose, CA, May 07 - 11, 2006.
Abstract:	This powerpoint presentation presents information on EPA modeling tools for wellhead protection. Presented is information on protection zone delineation using models; the Wellhead Decision Support System (WellHEDSS); and the WhAEM2000 model.

PRESENTATION	Potential Entrapment of Oil in a Tidal Marsh in Long Island New York	05/03/2006

BOUFADEL, M. AND J. W. WEAVER. Potential Entrapment of Oil in a Tidal Marsh in Long Island New York. Presented at 2006 Freshwater Spill Conference, Portland, OR, May 01 - 03, 2006.
Abstract:	This presentation describes hydraulic and biological characteristics of a tidal marsh located on the southern shore of Long Island, NY, coupled with transport simulations which indicated potential for entrapment of spilled oil in the marsh.

PRESENTATION	Modeling the Impacts of Land Use Change on Hydrology and Water Quality of a Pacific Northwest Watershed	11/06/2006

MOHAMOUD, Y. M. AND A. C. SIGLEO. Modeling the Impacts of Land Use Change on Hydrology and Water Quality of a Pacific Northwest Watershed. Presented at American Water Resources Association Annual Water Resources Conference, Baltimore, MD, November 06 - 09, 2006.
Abstract:	In many parts of the world, aquatic ecosystems are threatened by hydrological and water quality alterations due to extraction and conversion of natural resources for agriculture, urban development, forestry, mining, transportation, and water resources development. To evaluate the potential effect of urban development on hydrology and water quality, predictive models are often utilized. This study used the Hydrological Simulation Program- Fortran (HSPF) to assess the effects of land use change on hydrology and water quality of the Yaquina watershed near Newport, Oregon. The watershed land is currently used for silviculture. Because of its proximity to the coast, however, much of the watershed is a prime candidate for development, such as retirement community housing and vacation homes. Using hypothetical development scenarios, this study demonstrated that comprehensive watershed models can be an important land use planning tool for decision makers.

PRESENTATION	Raman Spectroscopy-Based Metabolomics for Differentiating Toxicities of Conazole Fungicides	06/24/2006

CHERNEY, D., D. R. EKMAN, D. J. DIX, AND T. W. COLLETTE. Raman Spectroscopy-Based Metabolomics for Differentiating Toxicities of Conazole Fungicides. Presented at Metabolomics Society Annual Meeting, Boston, MA, June 24 - 28, 2006.
Abstract:	Conazole fungicides are widely used both agriculturally for the protection of crops, and pharmaceutically in the treatment of topical and systemic infections. Heavy usage has created concern over the impact these compounds may have through environmental exposure to humans and other organisms. We have developed a Raman spectroscopy-based metabolomics approach, and have applied it to characterize the toxicities of three important conazole fungicides - myclobutanil, triadimefon, and propiconazole. These chemicals were chosen because they exhibit three different and known modes of toxicity. The Raman method proved capable of differentiating responses, via metabolomic analysis of urine collections, of rats exposed (individually) to these contaminants. A number of approaches were evaluated to reduce sample fluorescence to a level where adequate spectral information could be obtained. For example, a liquid-core optical fiber (or Raman waveguide) constructed of Teflon® AF allowed rapid sample photobleaching such that information-rich spectra could be acquired from urine without significant sample preparation. However, tangential flow filtration of the urine with a 500 nominal molecular weight limit filter, followed by Raman analysis with near-infrared laser excitation, proved a more robust method. Using this approach, we clearly observed changes in levels of important endogenous metabolites that were indicative of the toxic modes of action. The quality of PLS-DA models from the Raman data were comparable to those built using 1H- NMR data from the same set of urine samples. Analysis of Raman spectral changes that were related to chemical exposure yielded information that was consistent and complementary to that from NMR. With further development, the Raman approach may offer a viable metabolomics tool at a fraction of the instrumentation cost of NMR.

PRESENTATION	A Metabolomic Approach to Understanding Endocrine Disruption in Fathead Minnow	06/24/2006

EKMAN, D. R., T. W. COLLETTE, Q. TENG, G. T. ANKLEY, K. M. JENSEN, M. D. KAHL, AND D. L. VILLENEUVE. A Metabolomic Approach to Understanding Endocrine Disruption in Fathead Minnow. Presented at Metabolomics Society Annual Meeting, Boston, MA, June 24 - 28, 2006.
Abstract:	Although widely used in the study of rodent toxicity responses to assess human risk, metabolomics is now finding utility in toxicity assessments in a wide variety of other organisms including environmentally relevant small fish species such as fathead minnow (FHM) and medaka. To better understand temporal and dose responses to endocrine-disrupting chemicals (EDCs) within the hypothalamic-pituitary-gonadal (HPG) axis of FHM, we have begun a series of 1H-NMR and MS-based metabolomics studies using multiple tissues and biofluids. Reported here are the results of an exposure conducted using a model EDC, 17 alpha-ethinylestradiol (EE2), at two dose levels, with 192 fish being sampled at a number of time points during exposure and after an eight day depuration phase. This approach has proven useful as a tool to characterize different responses relative to dose and time, including what appears to be a compensation effect to extended exposure to the high dose of EE2 (100ng/L). In addition, feminization of the male fish appears to be described by similarities of the metabolite profiles with those of control females. We have also begun to explore the use of fish urine to assess toxicity, as this provides the potential for conducting non-lethal sampling of an important biofluid of fish. This would allow us to assess responses from an individual fish over the time course of an exposure, making any metabolomic analyses potentially more meaningful. To this end, we have begun an exhaustive NMR assignment of metabolites observed in spectra generated for urine derived from control males. In addition, a small-scale exposure was conducted using the EDC vinclozolin, to determine the utility of using urine for toxicity assessment.

PRESENTATION	Physicochemical Property Calculations	09/10/2006

CARREIRA, L. A., T. S. WHITESIDE, A. N. SARAVANARAJ, AND S. H. HILAL. Physicochemical Property Calculations. Presented at American Chemical Society Meeting, San Francisco, CA, September 10 - 14, 2006.
Abstract:	Computer models have been developed to estimate a wide range of physical-chemical properties from molecular structure. The SPARC modeling system approaches calculations as site specific reactions (pKa, hydrolysis, hydration) and `whole molecule' properties (vapor pressure, boiling point, molecular volume, diffusion coefficient, electron affinity, refractive index, Henry's constant, solubility, activity coefficient, liquid/liquid portioning). The system consists of a toolbox of base models whose parameters are shared across both site specific and whole molecule properties. The power of the technique is its ability to couple whole molecule and site specific chemistry to calculate new properties. For example water pKa and properties models are coupled to calculate the gas phase pKa and the pKa in any solvent or mixed solvent. pKa and property models are coupled to calculate tautomeric equilibrium constants in any solvent. pKa, hydrolysis and property models are coupled to calculate complex macro pKa's where ionization, hydrolysis and tautomerization may couple to yield very complex apparent pKa's. pKa and partition coefficient are coupled to calculate logD distributions as a function of pH. Several examples of complex modeling will be presented.

PRESENTATION	Calculation of Physicochemical Properties for Environmental Modeling	09/13/2006

HILAL, S. H., L. A. CARREIRA, T. WHITESIDE, AND A. N. SARAVANARAJ. Calculation of Physicochemical Properties for Environmental Modeling. Presented at American Chemical Society Meeting, San Francisco, CA, September 10 - 14, 2006.
Abstract:	Recent trends in environmental regulatory strategies dictate that EPA will rely heavily on predictive modeling to carry out the increasingly complex array of exposure and risk assessments necessary to develop scientifically defensible regulations. In response to this need, researchers at ERD-Athens and University of Georgia have developed a predictive modeling system SPARC (SPARC Performs Automated Reasoning in Chemistry) that calculates a large number of physical and chemical properties from molecular structure across all classes of organic chemicals. SPARC execution involves the classification of molecular structures and the selection and execution of appropriate mechanistic models, such as induction, resonance, and field effects to quantify reactivity. The basic mechanistic models in SPARC were designed and parameterized to be portable to any type of chemistry or organic chemical structure. This expanded prediction capability allows one to choose, for exhaustive validation, the reaction parameters for which large and reliable data sets exist. Resonance models were developed/calibrated on more than 5000 light absorption spectra, whereas electrostatic interaction models were developed using more than 4500 ionization pKas in water. Solvation models (i.e. dispersion, induction, etc) have been developed using more than 10000 physical property data points on properties such as vapor pressure, boiling point, solubility, activity coefficient, Henry's constant, GC retention times, Kow, etc. At the present time, SPARC predicts chemical properties such as gas phase electron affinity, ionization pKa, ester hydrolysis rate constant, heat of formation, chemical reduction potential and many other physical properties strictly from molecular structure.

PRESENTATION	Development of Near-Shore Hydrodynamic Models for Beach Closure Forecasting in the Great Lakes	02/22/2006

SCHWAB, D., D. BELETSKY, W. E. FRICK, Z. GE, M. MCCORMICK, A. WINKELMANN, AND A. FOLEY. Development of Near-Shore Hydrodynamic Models for Beach Closure Forecasting in the Great Lakes. Presented at 2006 Ocean Sciences Meeting, Honolulu, HI, February 20 - 24, 2006.
Abstract:	Water quality managers and other planning and decision entities are increasingly calling for up-to-the-minute data on present water quality conditions or forecasts of these data that can be used to adjust or respond to quickly developing activities with environmental implications. Examples include the forecast of short term water quality conditions for the withdrawal of water for drinking water supply; short range predictions of potentially dangerous conditions at water supply intakes; the forecast of beach closings and openings from bacterial contamination from combined sewer overflow (CSO); the knowledge of the trajectory of materials from dangerous spills; short range prediction of the impact of shoreline activities at one site or another shoreline site; and the forecasting of upwelling and downwelling events and the associated nutrient and bacterial redistributions required for toxic plankton blooms. This project intends to develop predictive nearshore hydrodynamic transport models of these phenomena.

PRESENTATION	Meeting in Tucson: 3mra: A Multi-Media Human and Ecological Modeling System for Site-Specific to National Scale Regulatory Applications	05/16/2006

LANIAK, G. F., J. E. BABENDREIER, S. KRONER, Z. SALEEM, K. L. WOLFE, AND R. S. PARMAR. Meeting in Tucson: 3mra: A Multi-Media Human and Ecological Modeling System for Site-Specific to National Scale Regulatory Applications. Presented at NSF Environmental Observatories Modeling Workshop: Grand Challenges of the Future for Environmental Modeling, Tucson, AZ, May 16 - 17, 2006.
Abstract:	3MRA provides a technology that fully integrates the full dimensionality of human and ecological exposure and risk assessment, thus allowing regulatory decisions a more complete expression of potential adverse health effects related to the disposal and reuse of contaminated wastestreams. 3MRA provides a technology that facilitates research, model development, and regulatory assessment. This, in turns, establishes a pathway for assimilating modeling-based research products directly into regulatory-based assessments.

PRESENTATION	Meeting in Tucson: Model Evaluation Science to Meet Today's Quality Assurance Requirements for Regulatory Use: Addressing Uncertainty, Sensitivity, and Parameterization	05/16/2006

BABENDREIER, J. E., K. L. WOLFE, R. S. PARMAR, AND G. F. LANIAK. Meeting in Tucson: Model Evaluation Science to Meet Today's Quality Assurance Requirements for Regulatory Use: Addressing Uncertainty, Sensitivity, and Parameterization. Presented at NSF Environmental Observatories Modeling Workshop: Grand Challenges of the Future for Environmental Modeling, Tucson, AZ, May 16 - 17, 2006.
Abstract:	The EPA/ORD National Exposure Research Lab's (NERL) UA/SA/PE research program addresses both tactical and strategic needs in direct support of ORD's client base. The design represents an integrated approach in achieving the highest levels of quality assurance in environmental decision-making, with technology development focuses on: (a) methods for holistic compositional and performance based model evaluation; (b) tools for uncertainty analysis and parameter estimation; (c) tools for conducting screening, local, and global-based sensitivity analyses; (d) tools for communicating uncertainty in outcomes and how best to reduce it; (e) methods and tools for addressing the computational burdens of quality assurance; (f) model evaluation demonstrations supporting selected research applications; and (g) national and international outreach efforts (leveraging collaborations and tools outside of EPA). This research is enhancing multimedia modeling and performance-based assessments underpinning major Agency initiatives. In the future, model evaluation will be a requisite decision-making component needed to analyze performance in achieving environmental benefits. Improving the overall efficiency of regulatory programs, this research is directly supporting multiple Program Office and ORD missions in allowing EPA to improve models and regulatory programs through better characterization of model sensitivities and uncertainties. Results from complementary approaches being undertaken to enhance model evaluation science and the Agency's capabilities will help EPA form the needed technical basis to: 1) better drive strategic research planning by identifying needs for improved science and data; 2) more accurately identify uncertainty in exposure and risk assessments of solid and hazardous waste management facilities; and 3) directly support the Office of Solid Waste and Emergency Response's (OSWER) Resource Conservation Challenge and One Cleanup Initiatives.

PRESENTATION	On-Line Tools for Proper Vertical Positioning of Vertical Sampling Intervals During Site Assessment: Meeting in Montgomery, Alabama	05/16/2006

WEAVER, J. W. AND V. GOROKHOVSKI. On-Line Tools for Proper Vertical Positioning of Vertical Sampling Intervals During Site Assessment: Meeting in Montgomery, Alabama. Presented at 17th Annual UST Assessment and Remediation Conference, Montgomery, AL, May 16 - 17, 2006.
Abstract:	This presentation, On-Line Tools for Proper Vertical Positioning of Sampling Intervals During Site Assessment, describes an approach to locating monitoring wells that is based on application of ground water models. The ideal use of both the model and site assessment funds is to construct an iterative modeling/data collection approach that draws on the strengths of both.

PRESENTATION	Meeting in Alabama: Evaluation of Uncertainty in the J&e Model	05/17/2006

WEAVER, J. W. AND F. TILLMAN. Meeting in Alabama: Evaluation of Uncertainty in the J&e Model. Presented at 17th Annual UST Assessment and Remediation Conference, Montgomery, AL, May 16 - 17, 2006.
Abstract:	This presentation presents an evaluation of uncertainty in the J&E model. The outline for the presentation is: challenges in vapor intrusion assessment; general commentary on modeling; uncertainty analysis on J&E model; uncertainty reduction analysis; generic best/worst case determination; and application to petroleum hydrocarbons.

PRESENTATION	Simulating Metabolism of Xenobiotic Chemicals as a Predictor of Toxicity	06/19/2006

JONES, W. J., P. K. SCHMIEDER, R. C. KOLANCZYK, AND O. MEKENYAN. Simulating Metabolism of Xenobiotic Chemicals as a Predictor of Toxicity. Presented at BOSC Review of the Computational Toxicology Program, Research Triangle Park, NC, June 19 - 20, 2006.
Abstract:	EPA is faced with long lists of chemicals that need to be assessed for hazard. A major gap in evaluating chemical risk is accounting for metabolic activation resulting in increased toxicity. The goals of this project are to develop a capability to forecast the metabolism of xenobiotic chemicals of EPA interest, to predict the most likely formed metabolites, and to interface that information with toxic effect models. Results will identify metabolites of equal or greater toxicity than the parent chemical. An existing metabolism simulator is being refined by focusing on reactions leading to increased toxicity for the effects endpoint of concern and which are currently simulated with low reliability. The toxic effect endpoint considered is endocrine disruption mediated by direct chemical binding to the estrogen receptor (ER). The principal reactions under investigation, ring oxidation and O-dealkylation, are those that result in hydroxylated metabolites predicted to bind the ER with greater affinity than the parent chemical. Chemicals for study were selected from EPA concern lists (food use inerts) provided by the Office of Prevention, Pesticides, and Toxic Substances (OPPTS) and include chemicals not predicted to be estrogenic as parent but for which forecasted metabolites are predicted to bind ER. Concurrent research will expand and enhance a QSAR for prediction of chemical binding to the ER as a means of assessing potential estrogenicity of parent chemicals and forecasted metabolites. Model results will be used to prioritize chemicals for further study and provide transformation reliability estimates. To enhance the simulator performance, chemical metabolism maps will be collected from the published literature and determined from in vitro rat hepatic microsome experiments. Newly acquired maps (and transformations) will be used to re-train the metabolism simulator and improve reliability estimates. In conjunction with metabolism experiments, analytical methods used to verify bioactivated metabolites formed in rat microsomes will be optimized to detect metabolites formed in fish liver tissue slices. Metabolically-competent liver slices from male fish that produce vitellogenin when exposed to xenobiotics will be used to study chemical bioactivation to ER-active forms. Data from these studies are used to improve the metabolic simulator and prioritize chemicals for testing that have the potential to be bioactivated to more toxic species. Metabolism data for training and improvement of the simulator will be stored and accessed using a database manager software under development. In addition, the database software is capable of search functions, depiction of metabolic maps, and provides access via structures to metabolism information and associated data collected from EPA's Office of Pesticide Programs (OPP). The database is specifically designed to store information submitted to EPA in support of pesticide registration such as pesticide metabolism in laboratory animals, plants, and livestock as well as environmental degradates. The database will be used by OPP risk assessors to increase efficiency of metabolism data access and performance of risk assessments. The system includes the ability to: depict hierarchical connection sequences of parent chemical and metabolites; track radiolabel within a pathway and combine/separate maps from associated studies; identify all maps (and parent structure) containing a specific metabolite of concern; search for sub-structures of toxicological concern and indicate its presence across chemicals and maps; and compare map similarity across chemicals and species. The database contains associated chemical identifiers as well as bioassay and analytical chemistry data. In its simplest mode, the database will furnish curated (verified) structures of chemicals/pesticides and their metabolites suitable for searches in other databases and provide metabolic maps plus tabulations of amounts of metabolites and other parameters. In a more advanced mode, the database will allow the risk assessor to perform searches for specific compounds and toxicophores and identify metabolism commonalities and differences across pesticides and species. At present, this process is performed manually and the results may vary among individual risk assessors. The database/software is expected to make this process more efficient, to furnish more reliable results, and to serve as a tool for hypothesis formulation by EPA researchers. Finally, prioritized chemical lists (based upon predicted toxic effects of parent chemical and metabolites) with transformation reliability estimates will be provided to OPPTS for chemical evaluations (risk assessments) and ranking for toxicity testing. This research will expand the knowledge-base of metabolic pathways and transformation products for important groups of toxic chemicals and demonstrate an approach that integrates metabolism simulation with toxic effects modeling.

PRESENTATION	Emerging Contaminants in Water and Current Health Issues	06/08/2006

RICHARDSON, S. D. Emerging Contaminants in Water and Current Health Issues. Presented at Seminar at the German Institute of Hydrology, Koblenz, GERMANY, June 08, 2006.
Abstract:	This presentation presents emerging contaminants in water and potential health effects. Contaminants talked about include the following: DBPs; PFOA; pharmaceuticals; pesticide degradation products; perchlorate; algal toxins; organotins; pathogens; naphthenic acids; and benzotriazoles.

PRESENTATION	A Metabolomic Approach to Understanding Endocrine Disruption in Fathead Minnow	11/06/2006

EKMAN, D. R., T. W. COLLETTE, Q. TENG, T. L. WHITEHEAD, G. T. ANKLEY, K. M. JENSEN, M. D. KAHL, AND D. L. VILLENEUVE. A Metabolomic Approach to Understanding Endocrine Disruption in Fathead Minnow. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Although widely used in the study of rodent toxicity responses to assess human risk, metabolomics is now finding utility in toxicity assessments in a wide variety of other organisms including environmentally relevant small fish species such as fathead minnow (FHM) and medaka. To better understand temporal and dose responses to endocrine-disrupting chemicals (EDCs) within the hypothalamic-pituitary-gonadal (HPG) axis of FHM, we have begun a series of 1H-NMR and MS-based metabolomics studies using multiple tissues and biofluids. Reported here are the results of an exposure conducted using a model EDC, 17 alpha-ethinylestradiol (EE2), at two dose levels, with 192 fish being sampled at a number of time points during exposure and after an eight day depuration phase. This approach has proven useful as a tool to characterize different responses relative to dose and time, including what appears to be a compensation effect upon extended exposure to the high dose of EE2 (100ng/L). In addition, exposure of the males to the high dose of EE2 produced a decrease in the similarity of their metabolite profiles while the exposed females responded in an opposite fashion by becoming more similar metabolically. Furthermore, feminization of the male fish appears to be described by similarities of their metabolite profiles with those of control females.

PRESENTATION	Raman Spectroscopy-Based Metabolomics for Differentiating Toxicities of Triazole Fungicides	11/06/2006

COLLETTE, T. W., D. CHERNEY, D. R. EKMAN, AND D. J. DIX. Raman Spectroscopy-Based Metabolomics for Differentiating Toxicities of Triazole Fungicides. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Conazole fungicides are widely used both agriculturally for the protection of crops, and pharmaceutically in the treatment of topical and systemic infections. Heavy usage has created concern over the impact these compounds may have through environmental exposure to humans and other organisms. We have developed a Raman spectroscopy-based metabolomics approach, and have applied it, as a proof-of-concept, to characterize the toxicities of three important conazole fungicides: myclobutanil, triadimefon, and propiconazole. These chemicals were chosen because they exhibit three different and known modes of toxicity. The Raman method proved capable of differentiating responses, via metabolomic analysis of urine collections, of rats exposed (individually) to these contaminants. Tangential flow filtration of the urine with a 500 nominal molecular weight limit filter, followed by Raman analysis with near-infrared laser excitation, proved a robust method, and avoided any interference from sample fluorescence. Using this approach, we clearly observed changes in levels of important endogenous metabolites that were indicative of the toxic modes of action. The quality of cluster-analysis models from the Raman data were comparable to those built using data from NMR spectroscopy (which is the more-standard metabolomic approach) from the same set of urine samples. Analysis of Raman spectral changes that were related to chemical exposure yielded information that was consistent and complementary to that from NMR. With further development, the Raman approach may offer a viable metabolomics tool at a fraction of the instrumentation cost of NMR. These encouraging results using the rat model have led us to extend and evaluate the Raman method to the analysis of urine from fathead minnow since eco-metabolomics applied to small fish models is an important goal of our metabolomics program.

PRESENTATION	Characterization of Metabolites in Small Fish Biofluids and Tissues By Nmr Spectroscopy	11/06/2006

TENG, Q., D. R. EKMAN, T. W. COLLETTE, T. L. WHITEHEAD, G. T. ANKLEY, K. M. JENSEN, M. D. KAHL, AND D. L. VILLENEUVE. Characterization of Metabolites in Small Fish Biofluids and Tissues By Nmr Spectroscopy. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Nuclear magnetic resonance (NMR) spectroscopy has been utilized for assessing ecotoxicity in small fish models by means of metabolomics. Two fundamental challenges of NMR-based metabolomics are the detection limit and characterization of metabolites (or NMR resonance assignments) with limited sample mass. To face these challenges, we have begun a comprehensive NMR resonance assignment of metabolites observed in spectra of liver for two important small fish models - fathead minnow and zebrafish - and also for urine in male fathead minnow. Reported here are the results of the assignment using a suite of two-dimensional NMR spectroscopy, including TOCSY, 1H/13C HMBC, 1H/13C HMQC and HR MAS spectra acquired on two 600 MHz NMR systems equipped with LC/NMR/MS and cryogenic probe at the EPA NMR facility in Athens, GA and a 800 MHz system at the University of Georgia. In addition, we will report on the identity of metabolites in these tissues and fluids that seem to be most related to exposure to important endocrine disrupting chemicals.

PRESENTATION	Acute and Chronic Effects of Fipronil and Its Enantiomers to Aquatic Organisms	11/06/2006

OVERMYER, J., W. A. WILSON, D. ROUSE, A. W. GARRISON, J. K. AVANTS, M. DELORENZO, P. KEY, K. CHUNG, B. KONWICK, AND M. BLACK. Acute and Chronic Effects of Fipronil and Its Enantiomers to Aquatic Organisms. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Fipronil is a phenylpyrazole insecticide used in agriculture and domestic settings for controlling various insect pests in crops, lawns and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (+) and (-) enantiomers and the racemic mixture of fipronil were assessed using Ceriodaphnia dubia (water flea), Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Chronic effects were also assessed using C. dubia. Results of the acute study showed that S. vittatum IS-7 was the most sensitive freshwater species while P. pugio was the most sensitive marine species. Ceriodaphnia dubia, S. vittatum IS-7, P. clarkii and P. pugio showed greater sensitivity to either a specific isomer or the racemate of fipronil. The (+) enantiomer was significantly more toxic to C. dubia and P. clarkii than the (-) enantiomer or the racemate; the racemate was significantly more toxic to S. vittatum IS-7 than either of the individual enantiomers. The (-) enantiomer was significantly more toxic to larval P. pugio than the (+) or the racemate; however, this was not observed with the adults. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. Ceriodaphnia dubia exposed in an 8-day chronic test showed significant decreases in reproduction and fitness indicators at lower concentrations of the (+) enantiomer compared to the racemic mixture or the (-) enantiomer. Neonates born during this time period showed a significant increase in mortality and decrease in fitness when exposed the (+) compared to the racemate or the (-) enantiomer. These results indicate that the most toxic isomer or racemate of fipronil is organism specific and that acute and chronic exposures can result in isomer specific toxicity.

PRESENTATION	Using 1h-Nmr Metabolomics to Characterize Altered Metabolic Profiles in Zebrafish (Danio Rerio) Exposed to the Model Edcs 17 Alpha-Ethinylestradiol (Ee2) and Fadrozole	11/06/2006

WHITEHEAD, T. L., T. W. COLLETTE, D. R. EKMAN, Q. TENG, G. T. ANKLEY, E. J. DURHAN, K. M. JENSEN, M. D. KAHL, AND D. L. VILLENEUVE. Using 1h-Nmr Metabolomics to Characterize Altered Metabolic Profiles in Zebrafish (Danio Rerio) Exposed to the Model Edcs 17 Alpha-Ethinylestradiol (Ee2) and Fadrozole. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Elevated levels of endocrine-disrupting chemicals (EDCs) have been reported in waterways worldwide and have been shown to affect numerous aspects of development, behavior, reproduction, and survival in various fish species. We have examined the effects of the synthetic steroid 17 alpha-ethinylestradiol (EE2) and the cytochrome P450 19 (aromatase) inhibitor fadrozole (FAD) on endogenous metabolite levels in reproductively mature zebrafish (Danio rerio). EE2 is a highly specific and potent agonist of the estrogen receptor used extensively in the U.S. as an active ingredient in oral contraceptives. It has been observed in aquatic environments and is therefore considered relevant as an environmental contaminant. FAD has been used extensively in breast cancer research as an inhibitor of aromatase activity and has been shown to bind reversibly to aromatase in birds, mammals, and fish. For this study, fish were exposed to two concentrations of EE2 (30 or 100 ng/L) or FAD (25 or 100 micrograms/L) or control water for 96 hours in a flow-through system followed by a 96 hour depuration phase prior to collection. Endogenous metabolites were profiled in liver and gonad extracts using 1H- NMR-based metabolomics techniques. Principal Components Analysis (PCA) and Partial Least-Squares Discriminant Analysis (PLS-DA) were employed to define metabolites responsible for class separation between control, low-dose exposure, and high-dose exposure populations. Ultimately, differential metabolic profiles will provide predictive biomarkers for risk assessment and support computational toxicology modeling efforts to characterize toxicity pathways of environmentally-relevant compounds in a systems- and population-modeling context.

PRESENTATION	Gasoline Composition in the US (1976-2005)	06/12/2006

WEAVER, J. W., L. M. PRIETO, AND L. R. EXUM. Gasoline Composition in the US (1976-2005). Presented at 15th Annual State Fund Administrators Conference, Oklahoma City, OK, June 11 - 14, 2006.
Abstract:	Gasoline composition data are collected by EPA for Clean Air Act compliance requirements, by industry for various purposes and, recently, by EPA/ORD for a compositional study (Weaver et al., 2005, EPA/600/R-05/032, http://www.epa.gov/athens). Each of these data sets are potentially valuable for evaluation of potential environmental impacts from gasoline and impacts on remediation. This part of the study uses thirty years' of industry data from approximately 175 cities, and shows the trends in lead, vapor pressure, benzene, ethers and alcohols. Samples are collected and analyzed by a voluntary industry consortium, currently organized by Northop Grumman Corp in Bartlesville, Oklahoma (http://pps.ms.northropgrumman.com/default.htm). The interpretation of data from these studies requires an understanding of federal and state regulations on fuel composition. Multiple sources of information on these programs were used to develop reliable, up-to-date maps showing gasoline requirements imposed by various regulations. In addition to the insights provided by these comparison of data for cities under differing regulatory requirements, models of each city¿s composition are been developed. These will provide a means to estimate release composition given an estimated release data. This information is anticipated to be useful for site assessment and modeling of sites.

PRESENTATION	The Enantioselectivity of Chiral Pesticides Presents a Green Chemistry Opportunity	08/28/2006

GARRISON, A. W. The Enantioselectivity of Chiral Pesticides Presents a Green Chemistry Opportunity. Presented at 2006 Gordon Research Conference on Green Chemistry, Oxford, UK, August 27 - September 01, 2006.
Abstract:	This presentation will include a summary of the use and environmental occurrence of modern chiral pesticides with data on their enantioselective fate and effects. Information on enantioselectivity will facilitate a science-based approach toward fostering the production and use of single- or enriched-enantiomer pesticides that would relieve the environment of thousands of tons of unnecessary chemicals which, in the worst cases, may have adverse impacts.

PRESENTATION	Effects of Mountaintop Mining/Valley Fill (Mtm/Vf) on Functional Indicators in Appalachian Headwater Streams	06/20/2006

BURKE, R. A., S. FULTON, K. M. FRITZ, B. R. JOHNSON, AND C. BARTON. Effects of Mountaintop Mining/Valley Fill (Mtm/Vf) on Functional Indicators in Appalachian Headwater Streams. Presented at EPA Regional Science Workshop on Headwaters and Associated Wetlands in the Mid-Atlantic Highlands Region, Philadelphia, PA, June 20 - 21, 2006.
Abstract:	The objectives of this poster were 1)to evaluate the impact of MTM/VF on the functional attributes SOD, soil/sediment respiration rate, soil/sediment DEA and dissolved trace gas concentrations across gradients of mining disturbance and hydrolgy and 2)compare these functional attributes in ephemeral and intermittent channels and adjacent upland soils to evaluate whether or not headwater channels are hotspots of C and/or N cycling.

PRESENTATION	Meeting in Philadelphia: Nutrient Concentrations in Flowing Waters of the South Fork Broad River, Georgia Watershed	06/21/2006

BURKE, R. A., J. MOLINERO, D. L. SPIDLE, AND L. M. PRIETO. Meeting in Philadelphia: Nutrient Concentrations in Flowing Waters of the South Fork Broad River, Georgia Watershed. Presented at EPA Regional Science Workshop on Headwaters and Associated Wetlands in the Mid-Atlantic Highlands Region, Philadelphia, PA, June 20 - 21, 2006.
Abstract:	The objective of this poster is by comparing nutrient and DOM concentrations in small and large streams, we hope to better understand: (1) watershed controls on stream nutrient and DOM concentrations; and (2) the variability of nutrient and DOM concentrations within a river network.

PRESENTATION	Control of Single-Couple Oxidation State By Simultaneous Reduction and Oxidation in Non-Equilibrium Complex Systems	06/26/2006

WASHINGTON, J. W. AND R. THOMAS. Control of Single-Couple Oxidation State By Simultaneous Reduction and Oxidation in Non-Equilibrium Complex Systems. Presented at 2006 Gordon Research Conference on Environmental Sciences: Water, Plymouth, NH, June 25 - 30, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Presentation in Atlanta: Working to Keep Waste Out of the Landfills and Streams EPA Region 4 Response Support Corps Activities, a Personal Perspective	07/11/2006

KITCHENS, J. Presentation in Atlanta: Working to Keep Waste Out of the Landfills and Streams EPA Region 4 Response Support Corps Activities, a Personal Perspective. Presented at Atlanta Federal Health & Safety Council, Atlanta, GA, July 11, 2006.
Abstract:	In the aftermath of Hurricane Katrina it became evident that there were a multitude of problems created by the storm. Although human concerns were foremost, it became evident that during recovery environmental problems must be addressed. The Environmental Protection Agency's effort in the wake of Katrina was to minimize and mitigate damage to the environment. The EPA responded with many resources and personnel; however, due to the enormity of the area affected, more personnel were needed to assist in these efforts. This is where the EPA Region 4 Response Support Corps comes into the picture. The Corps is composed of personnel throughout the Agency who have committed their time to assist in time of great need. They operate on a purely volunteer basis and with the blessing and support of their management. This presentation is a personal perspective of one EPA employee who volunteered to help with the cleanup efforts in Mississippi.

PRESENTATION	Changing Climate and Photobiogeochemical Cycles in Aquatic Environments	07/11/2006

ZEPP, R. G., D. J. ERICKSON III, N. D. PAUL, AND B. A. SULZBERGER. Changing Climate and Photobiogeochemical Cycles in Aquatic Environments. Presented at 33rd American Society for Photobiology Meeting, Rio Grande, PUERTO RICO, July 08 - 12, 2006.
Abstract:	Global biogeochemistry plays a critical role in controlling life processes, climate and their interactions, including effects on atmospheric greenhouse gas concentrations. Recent evidence indicates that the light-driven part of aquatic biogeochemical cycles is being altered by interactive global changes in solar UV irradiance, warming, precipitation, clouds and atmospheric circulation. Four specific examples are reviewed here: 1) changes in runoff from land to water; 2) changes in stratification and mixing; 3) warming-induced changes in microbial cycling of UV-absorbing colored dissolved organic matter; 4) changes in water to atmosphere fluxes of trace gases. For example, warming and precipitation change can alter the transfer of organic matter from terrestrial to aquatic ecosystems and thereby influence UV penetration into water bodies, with major consequences for aquatic biogeochemical processes. Moreover, future changes in climate may enhance stratification, reduce vertical mixing and alter the mixed layer depth of lakes and the ocean, which will alter UV effects on biogeochemistry in the surface layer. These changes in biogeochemistry include modification of carbon cycling that is linked to effects on the cycling of metals and mineral nutrients such as nitrogen. Changes in metal cycling can also affect the light-induced production of reactive oxygen species in aquatic systems, and these changes in oxidative activity affect contaminant decomposition and microbial cycling of carbon and other elements. Interactions between changing solar UV and climate change in aquatic environments are changing water-to-atmosphere exchange of trace gases, such as methyl bromide and dimethylsulfide. Methyl bromide can catalyze depletion of the ozone layer and oceanic emissions of dimethylsulfide produce particulates (i.e., sulfate aerosols) that directly and indirectly (via clouds) have a cooling effect on the marine atmosphere.

PRESENTATION	Relationship of Microbial Community Structure and Carbon Dynamics in Soils from Brazilian Savannas	08/21/2006

MOLINA, M., R. G. ZEPP, A. KOZOVITS, J. BRESOLIN, AND M. BUSTAMANTE. Relationship of Microbial Community Structure and Carbon Dynamics in Soils from Brazilian Savannas. Presented at 11th International Symposium on Microbial Ecology, Vienna, AUSTRIA, August 20 - 25, 2006.
Abstract:	Fertilization is a widespread management practice in savanna areas of central Brazil (Cerrado) that are undergoing rapid agricultural land use changes. We conducted field and laboratory studies in soils with added fertilizers to determine the effect that fertilization of native areas have on microbial composition and decomposition rates of soil organic matter (SOM) pools. We compared microbial communities from native (savanna and forest) and managed (pasture and N, P, N+P, Ca-fertilized savanna) areas using phospholipid fatty acid analysis (PLFAs) and fungal to bacterial ratios. The structure of the microbial community varied as a function of the fertilization treatment and management practice (p<0.000l). Calcium and the control treatment exhibited the same community structure and had a higher concentration of Gram negative biomarkers, while N, P, and N+P treatments had a higher concentration of Gram positive biomarkers and similar microbial communities. Phosphorus amendments produced the highest fungal:bacterial ratio after 10 days of fertilization. The effect of added fertilizers was further studied in the laboratory using gas-tight jars containing soils amended with N and P. Results from a two-compartment model indicated that although N and P treatments produced very similar decay constants for the labile C, P addition enhanced CO2 evolution from the more refractory SOM. CO was taken up by the soil cores in all cases. CO deposition velocities were enhanced by the addition of fertilizer with particularly large effects observed with soil cores amended by P. This study indicates that the presence of fertilizers significantly affects the amount and type of C that is recycled by the microbial community in Cerrado soils.

PRESENTATION	Data for Environmental Modeling: An Overview	07/11/2006

LANIAK, G. F. Data for Environmental Modeling: An Overview. Presented at International Environmental Modelling and Software Society Conference, Burlington, VT, July 09 - 13, 2006.
Abstract:	The objective of the project described here, entitled Data for Environmental Modeling (D4EM), is the development of a comprehensive set of software tools that allow an environmental model developer to automatically populate model input files with environmental data available from both local and internet-based databases. Included in this project summary are descriptions of: 1) the range of data needs associated with modern environmental assessments, 2) key software development decisions and strategies, 3) a description of the D4EM system design, and 4) a description of the relationship between the D4EM software system and environmental models and modeling systems.

PRESENTATION	Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Chloraminated Drinking Water	08/17/2006

RICHARDSON, S. D., F. G. CRUMLEY, K. BUETTNER, J. J. ELLINGTON, J. J. EVANS, B. C. BLOUNT, L. K. SILVA, F. L. CARDINALI, M. J. PLEWA, E. D. WAGNER, R. J. MILTNER, G. LUTHER, T. WAITE, AND A. B. MCKAGUE. Occurrence of Iodo-Acid and Iodo-Thm Disinfection By-Products in Chloraminated Drinking Water. Presented at Gordon Research Conference on Drinking Water Disinfection By-Products, South Hadley, MA, August 13 - 18, 2006.
Abstract:	Iodo-acids were recently identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid (IAA), bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. There is concern about these new iodo-acid DBPs because mammalian cell toxicity studies have revealed that IAA is highly cytotoxic and genotoxic¿with a genotoxicity 2X that of regulated bromoacetic acid. IAA has also been shown to cause developmental effects in mouse embryos. New evidence indicates that iodinated DBPs may be increased in formation in chloraminated vs. chlorinated drinking water, and this is of concern because many water utilities are switching from chlorine to chloramines. We developed a negative chemical ionization mass spectrometry method to measure these iodo-acids in drinking water and are conducting an occurrence study of these iodo-acids in chloraminated drinking waters across the U.S.

PRESENTATION	Evaluating the Regional Predictive Capacity of a Process-Based Mercury Exposure Model (R-Mcm) for Lakes Across Vermont and New Hampshire, USA	11/06/2006

KNIGHTES, C. D. Evaluating the Regional Predictive Capacity of a Process-Based Mercury Exposure Model (R-Mcm) for Lakes Across Vermont and New Hampshire, USA. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Regulatory agencies are confronted with a daunting task of developing fish consumption advisories for a large number of lakes and rivers with little resources. A feasible mechanism to develop region-wide fish advisories is by using a process-based mathematical model. One model of this type is the Regional Mercury Cycling Model (R-MCM), which has been specifically designed to model a series of lakes for a given region. Using the Regional Environmental Monitoring Assessment Program (REMAP) data set, R-MCM was applied to 91 lakes across Vermont and New Hampshire using a series of parameter refinement tiers. Using the simplest application through site-specific parameterization, visual analyses and statistical metrics were used to evaluate the trends in simulated results versus observed mercury concentrations. R-MCM was found to generally under-predict HgT and MeHg water column concentrations, while over-predicting sediment MeHg concentrations. Through a series of progressive parameter refinements, potential improvements in model prediction were evaluated as a function of the different model parameters. Separation of observed and predicted data by lake characteristics identified some patterns of bias and fit, but it was difficult to make any solid conclusions regarding model performance versus lake type. Default level input parameterization produced the largest amount of scatter in the predicted data points. By using site-specific values for the default level characteristics, scatter was reduced but model performance was not generally improved. This analysis demonstrates that R-MCM and the general state of mercury science and modeling are not at a point where fish advisories can be determined using a regional predictive model a priori. However, this work suggests that need for additional research on the transport and transformation of mercury to account for higher total mercury and methylmercury concentrations in these water bodies.

PRESENTATION	Mercury Cycling and Biomagnification	11/06/2006

HOFF, D., J. M. JOHNSTON, AND C. DUCHENEAUX. Mercury Cycling and Biomagnification. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Montreal, QC, CANADA, November 05 - 09, 2006.
Abstract:	Mercury cycling and biomagnification was studied in man-made ponds designed for watering livestock on the Cheyenne River Sioux Reservation in South Dakota. Multiple Hg species were quantified through multiple seasons for 2 years in total atmospheric deposition samples, surface water, shallow ground water, sediments, soils, plankton, macroinvertebrates and fish. No point source contamination of Hg was found during the investigation. Atmospheric deposition was the only documented source of Hg loading to the systems. The highest concentrations of methyl Hg occurred in plankton samples, while the average percent methyl Hg of total Hg was similar to that of water. These findings suggest that plankton is a key component to understanding the biological biomagnification of Methyl Hg in these systems. Additionally, plankton Hg concentrations varied temporally with water concentrations. Fish burdens of Hg ranged up to 1.5 ppm in Northern Pike and were not temporally dependent.

PRESENTATION	Chlorinated Vs. Chloraminated Drinking Water: Toxicity-Based Identification of Disinfection By-Products Using Esi-MS and Esi-MS/MS	11/30/2006

RICHARDSON, S. D., F. G. CRUMLEY, M. J. PLEWA, E. D. WAGNER, T. H. MIZE, AND R. ORLANDO. Chlorinated Vs. Chloraminated Drinking Water: Toxicity-Based Identification of Disinfection By-Products Using Esi-MS and Esi-MS/MS. Presented at 19th Annual Tandem Mass Spectrometry Workshop, Lake Louise, AB, CANADA, November 29 - December 02, 2006.
Abstract:	Drinking water disinfection by-products (DBPs) are of concern because some epidemiologic studies have shown that some DBPs are associated with cancer or adverse reproductive/developmental effects in human populations, and other studies have shown that certain DBPs cause similar health effects in laboratory animals. As a result, the U.S. EPA has regulated several DBPs. However, more than 500 DBPs have been reported in drinking water for which little or no occurrence and health data exist. In addition, there is almost no information on high molecular weight DBPs (>1000 Da), which are indicated to comprise >50% of the total organic halide (TOX) from chlorinated drinking water. None of these high molecular weight halogenated by-products have ever been precisely identified, and there is no information on potential toxicity of this high molecular weight fraction. There is also very little information regarding highly polar DBPs, which are missed by most commonly used analytical techniques. The goal of this research is to use a bio-assay directed approach to focus identification work on the most toxicologically important DBPs. To this end, drinking water is being collected from full-scale treatment plants that use chlorine, ozone, chlorine dioxide, and chloramines as disinfectants, and this drinking water is being fractionated initially according to molecular size (through the use of ultrafiltration membranes). Previous results from our research have shown that most of the toxicity resides in the <1000 Da fraction, with significant toxicity also in the 1000-5000 Da fraction. New research is further refining these fractions and investigating molecular weight fractions of <500, 500-1000, 1000-3000, 3000-5000, and >5000 Da. A mammalian cell genotoxicity/cytotoxicity assay is being used to determine the toxicity of each fraction and to direct the identification work. Gas chromatography (GC) with high resolution mass spectrometry (MS) is being used to identify the lower molecular weight, non-polar drinking water DBPs; ESI-MS and ESI-MS/MS with a linear ion trap-Fourier transform (FT) mass spectrometer are being used to obtain structural information on high molecular weight and highly polar DBPs. Tentative identifications of new chloro-bromo DBPs will be presented, along with new toxicity information on the five molecular weight fractions collected.

PRESENTATION	Dissolved Methane in the Sills Area, Gulf of California, Mexico	10/24/2006

MORALES, K. C., J. V. MACIAS ZAMORA, AND R. A. BURKE. Dissolved Methane in the Sills Area, Gulf of California, Mexico. Presented at Workshop on Oxygen Minimum Systems in the Ocean: Distribution, Diversity and Dynamics , Concepcion, CHILE, October 24 - 26, 2006.
Abstract:	The northern part of the Gulf of California is physically separated from the rest of the Gulf by a series of sills and islands. Its waters are highly productive as several water masses interact with each other at the sills. One of the characteristics in the area is the presence of the Oxygen Minimum Zone located just south of the sills. Its chemical manifestation can probably be best observed by methane concentrations in the water column. We decided to measure the distribution of methane concentration in the water column in this area to serve as a tracer of mixing water masses.

PRESENTATION	Bacteria, Beaches and Swimmable Waters: Introducing Virtual Beach	11/06/2006

FRICK, W. E. Bacteria, Beaches and Swimmable Waters: Introducing Virtual Beach. Presented at 4th International Conference on Marine Waste Water Discharges and Coastal Environment, Antalya, TURKEY, November 06 - 10, 2006.
Abstract:	Safe beaches meet water quality standards and are valued for their aesthetics and the recreational opportunities that they afford. In the United States recreational water quality assessments and beach closure decisions are presently based on samples of enterococci or Escherichia coli that typically take a day or more to culture and develop. Thus decisions to close beaches are generally based on old information that, due to the great daily variability in bacteria concentrations, leads to an unsatisfactory number of false positive and negative outcomes. Beaches are closed when they could be open and open when they should be closed, no one knowing their true status until the next day. Researchers have shown that various techniques, including empirical statistical models, can provide better results. To make such models generally available to the public, the EPA Office of Research and Development, in collaboration with the USGS, NOAA, and others, is developing the Virtual Beach model platform. Virtual Beach is designed to provide the public tools for developing site-specific predictive models for its beaches. Virtual Beach features both the multiple linear regression (MLR) and time-series forecasting techniques to relate indicator bacteria concentration to predictor variables. It emphasizes the value of data inspection, transformations, interaction terms, adjustment for time-series effects, identification of outliers, and model selection criteria. R2 and Cp statistics are joint criteria in the model selection process. The value of dynamic modeling, that explicitly recognizes the fact that beach conditions often reflect longer-term dynamic variations, is investigated and documented. Virtual Beach was tested with the Huntington Beach, Ohio 2006 summer bacteria data that was disseminated daily on the internet. The findings support the conclusion that readily available environmental data may be effective, where such data are available, in nowcasting and forecasting bacteria concentrations at locations around the world.

PRESENTATION	Capabilities and Limitations of Contaminant Transport Models	09/26/2006

WEAVER, J. W. Capabilities and Limitations of Contaminant Transport Models. Presented at Brownfields West Virginia: Risk and Rewards, Charleston, WV, September 26, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Model Parameter Estimation	09/27/2006

WEAVER, J. W. Model Parameter Estimation. Presented at Workshop on the Application to Fate/Transport Modeling to the Remedial Decision Making Process, Charleston, WV, September 27, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Meeting in West Virginia: Modeling for Environmental Decision Making	09/27/2006

WEAVER, J. W. Meeting in West Virginia: Modeling for Environmental Decision Making. Presented at Workshop on the Application to Fate/Transport Modeling to the Remedial Decision Making Process, Charleston, WV, September 27, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Comments and Observations: Particulate Matter Case Study	10/11/2006

BABENDREIER, J. E. Comments and Observations: Particulate Matter Case Study. Presented at NSF-EPA TransAtlantic Uncertainty Colloquium, Washington, DC, October 10 - 11, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	In Vitro Metabolism Research at NERL/Erd: An Overview of Conazole Fungicides	10/11/2006

KENNEKE, J. F. AND C. S. MAZUR. In Vitro Metabolism Research at NERL/Erd: An Overview of Conazole Fungicides. Presented at Metabolism Research Meeting, Research Triangle Park, NC, October 11, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Emerging Drinking Water Disinfection By-Products and New Health Issues: Meeting in Savannah	10/06/2006

RICHARDSON, S. D. Emerging Drinking Water Disinfection By-Products and New Health Issues: Meeting in Savannah. Presented at Environmental Symposium at Atlantic State University, Savannah, GA, October 06, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Modeling Urban Development Impacts With Hspf	11/09/2006

MOHAMOUD, Y. M. Modeling Urban Development Impacts With Hspf. Presented at Clarksburg Integrated Monitoring Team, Clarksburg, MD, November 09, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Meeting in Westford, Ma: Gasoline Composition in the U.S. (1976-2005)	11/02/2006

WEAVER, J. W., L. R. EXUM, AND L. M. PRIETO. Meeting in Westford, Ma: Gasoline Composition in the U.S. (1976-2005). Presented at MTBE and Other Fuel Oxygenates: Considerations for Assessments and Remediation, New England Interstate Water Pollution Control Commission, Westford, MA, November 02 - 03, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Meeting in Westford, Ma: Plume Formation, Transport and Modeling	11/02/2006

WEAVER, J. W. Meeting in Westford, Ma: Plume Formation, Transport and Modeling. Presented at MTBE and Other Fuel Oxygenates: Considerations for Assessments and Remediation, New England Interstate Water Pollution Control Commission, Westford, MA, November 02 - 03, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Meeting in Westford, Ma: Model Parameter Estimation	11/02/2006

WEAVER, J. W. Meeting in Westford, Ma: Model Parameter Estimation. Presented at MTBE and Other Fuel Oxygenates: Considerations for Assessments and Remediation, New England Interstate Water Pollution Control Commission, Westford, MA, November 02 - 03, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Mass Spectrometry and Toxicity Characterization of Drinking Water Fractions: Are High Molecular Weight DBPs Toxic?	11/30/2006

RICHARDSON, S. D., F. G. CRUMLEY, F. FASANO, M. J. PLEWA, E. D. WAGNER, L. WILLIAMSON, M. BARTLETT, P. ANGEL, AND R. ORLANDO. Mass Spectrometry and Toxicity Characterization of Drinking Water Fractions: Are High Molecular Weight DBPs Toxic? Presented at 19th Annual Tandem Mass Spectrometry Workshop, Lake Louise, AB, CANADA, November 29 - December 02, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Chemistry, Reactivity, and Formation of Disinfection By-Products	11/04/2006

RICHARDSON, S. D., C. RAV-ACHA, AND G. D. SIMPSON. Chemistry, Reactivity, and Formation of Disinfection By-Products. Presented at American Water Works Association Water Quality Technology Conference, Denver, CO, November 03 - 05, 2006.
Abstract:	There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Selection and Calibration of Subsurface Reactive Transport Models Using a Surrogate-Model Approach	12/15/2006

MATOTT, L. S. AND A. J. RABIDEAU. Selection and Calibration of Subsurface Reactive Transport Models Using a Surrogate-Model Approach. Presented at American Geophysical Union Fall 2006 Meeting, San Francisco, CA, December 11 - 15, 2006.
Abstract:	While standard techniques for uncertainty analysis have been successfully applied to groundwater flow models, extension to reactive transport is frustrated by numerous difficulties, including excessive computational burden and parameter non-uniqueness. This research introduces a novel surrogate-based method that overcomes such difficulties by utilizing a global search technique that samples from a hierarchy of candidate reactive transport models. During calibration, the search algorithm is driven toward least-squares minimization of the most parsimonious model that best matches the available calibration data. This surrogate-model approach is demonstrated via application to several nitrate contamination problems. Results indicate that, due to the utilization of simpler models in regions of parameter insensitivity, the method is able to identify quality model fits at reduced computational expense, relative to traditional techniques. Furthermore, comparisons with a formal multi-model ranking procedure suggest the new approach is a promising tool for multi-model ranking and selection.

PRESENTATION	IMPACT OF BT ( BACILLUS THURINGIENSIS ) CROPS ON BAT ACTIVITY IN SOUTH TEXAS AGROECOSYSTEMS	10/19/2006

KENNARD, K. S., T. G. HALLAM, S. T. PURUCKER, J. K. WESTBROOK, AND G. F. MCCRACKEN. IMPACT OF BT ( BACILLUS THURINGIENSIS ) CROPS ON BAT ACTIVITY IN SOUTH TEXAS AGROECOSYSTEMS. Presented at 36th Annual North American Symposium on Bat Research, Wilmington, NC, October 18 - 21, 2006.
Abstract:	The widespread adoption of transgenic insecticidal crops raises concerns that nontarget species may be harmed and food webs disrupted. The goal of this research is to determine how transgenic Bt (Bacillus thuringiensis) crops impact the activity of Brazilian freetailed bats (Tadarida brasiliensis), an abundant natural predator of insect pests in the agricultural region of South Central Texas. We predicted that bat activity would be reduced over Bt crops during periods of local emergence of insect pests. We used twelve Anabat II detectors to monitor bats foraging over Bt and non-Bt corn and cotton fields. Bat activity, measured by the number of calls, was less over Bt fields at some sites. Bat activity also varied between sites and over time, possibly reflecting different insect densities and distances to major roosts. This study has conservation implications for declining bat populations.

PRESENTATION	Spatial Analysis and Decision Assistance (Sada) Training Course	10/25/2006

PURUCKER, S. T. Spatial Analysis and Decision Assistance (Sada) Training Course. Presented at University of Tennessee, Knoxville, TN, October 25 - 27, 2006.
Abstract:	Spatial Analysis and Decision Assistance (SADA) is a Windows freeware program that incorporates tools from environmental assessment into an effective problem-solving environment. SADA was developed by the Institute for Environmental Modeling at the University of Tennessee and includes integrated modules for GIS, visualization, geospatial analysis, statistical analysis, human health and ecological risk assessment, cost/benefit analysis, sampling design, and decision support. SADA began in the middle 1990s as a simple tool for integrating human health risk with spatial modeling tools. Since then, SADA has continued as an evolving freeware product targeted to individuals needing the integration or expansion of existing models into a spatial context. Because of the varied user base, SADA was engineered with an open and highly scaleable environment that in most cases allows additional functionality without an apparent increase in complexity. As a result, applications of SADA have extended into other disciplines that place strong emphasis on the spatial distribution of data. This paper provides an overview of the central functions of SADA and discusses how we addressed the problem of presenting complex and integrated models in a tractable manner. Information on SADA and a free download of the program can be found at http://www.tiem.utk.edu/~sada/.

PUBLISHED REPORT	User Manual for Express, the Exams-Przm Exposure Simulation Shell	09/28/2006

BURNS, L. A. User Manual for Express, the Exams-Przm Exposure Simulation Shell. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/095 (NTIS PB2007-100140), 2006.
Abstract:	The Environmental Fate and Effects Division (EFED) of EPA's Office of Pesticide Programs(OPP) uses a suite of ORD simulation models for the exposure analysis portion of regulatory risk assessments. These models (PRZM, EXAMS, AgDisp) are complex, process-based simulation codes that combine chemical and physical data required by EPA of industry with agronomic, physiographic , and limnological descriptions of the environmental settings into which pesticides are released. This complexity, while providing significant sophistication and specificity in analysis, has posed difficulties in maintaining a transparent, reproducible process clearly devoid of arbitrariness in parameter selections, exposure metrics, and interpretation of ecological and human health risks. This project was undertaken to develop a Graphical User Interface (GUI) to combine regulatory simulation models, their supporting databases, regulatory "scenarios" for major crops, and data input screens for chemical properties into a user-friendly "simulation shell" lending itself to consistent analytical practices and reproducible exposure and risk assessments. The resulting computer software "Express (the EXAMS - PRZM Exposure Simulation Shell)" is a joint project of EFED and ORD. EFED designed and funded an initial draft of the Express software, and retains responsibility for developing and maintaining crop-specific modeling scenarios for regulatory analyses. ORD is responsible for continuing development, quality control, maintenance, and public availability of the software and its constituent models and analytical modules. With the completion of Express, exposure metrics (peak, 4-day, 21-day, 60-day, annual) for ecological and human health risk assessments can be easily and conveniently and, as importantly, reproducibly, developed for any or all of the agronomic scenarios developed by EFED. Probabilistic analyses (Weibull distribution) of these exposure metrics are derived by coupling 30-year time-series of meteorological data to linked PRZM/EXAMS simulation studies. Express significantly reduces the variability, lack of reproducibility by external analysts, and perceived arbitrariness of EPA's regulatory processes for determining the safety and appropriate uses of registered pesticides.

PUBLISHED REPORT	Determining Active Oxidant Species Reacting With Organophosphate Pesticides in Chlorinated Drinking Water	09/28/2006

DUIRK, S. E., D. CHERNEY, C. TARR, AND T. W. COLLETTE. Determining Active Oxidant Species Reacting With Organophosphate Pesticides in Chlorinated Drinking Water. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/103 (NTIS PB2007-100144), 2006.
Abstract:	Chlorpyrifos (CP) is an organophosphate (OP) pesticide that was used as a model compound to investigate the transformation of OP pesticides at low pH and in the presence of bromide and natural organic matter (NOM) under drinking water treatment conditions. Raman spectroscopy was used to determine which active chlorine species was responsible for the rapid oxidation of CP below neutral pH. Over the pH range of 2-11, three active chlorine species were identified with Raman bands of 725, 711, and 538 cm-1. The first two bands were easily assigned to HOCl and OCl- respectively. The 538 cm-1 band was identified as Cl2(aq) after bubbling chlorine gas through phosphate buffered water at pH 2. Either at low pH or in water treatment plants that use direct injection of Cl2(g), molecular chlorine rapidly reacts with CP transforming it to chlorpyrifos oxon (CPO). In the presence of bromide, the loss of CP was found to be accelerated when aqueous chlorine was added. It was found that bromide acts as a catalyst in the oxidation of CP to CPO via the formation of hypobromous acid (HOBr) at concentrations relevant to drinking water treatment. Also, NOM was found to not inhibit the oxidation of CP to CPO in the presence of free chlorine under the experimental conditions in this study. A previously developed screening-level model used to predict OP pesticide degradation pathways was modified to model the effects of both bromide and NOM. The model adequately described the oxidation of CP to CPO by free chlorine as well as the stability of CPO over the course of the experiment. This work demonstrated the applicability of screening-level models to predict the fate of OP pesticides under drinking water treatment conditions.

PUBLISHED REPORT	Estimation of Hydrolysis Rate Constants of Carboxylic Acid Ester and Phosphate Ester Compounds in Aqueous Systems from Molecular Structure By Sparc	09/28/2006

HILAL, S. H. Estimation of Hydrolysis Rate Constants of Carboxylic Acid Ester and Phosphate Ester Compounds in Aqueous Systems from Molecular Structure By Sparc. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/105 (NTIS PB2007-100142), 2006.
Abstract:	SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external mechanistic perturbation components. The internal perturbations quantify the interactions of the appended perturber (P) with the reaction center (C). These internal perturbations are factored into SPARC's mechanistic components of electrostatic and resonance effects. External perturbations quantify the solute-solvent interactions (solvation energy) and are factored into H-bonding, field stabilization and steric effects. These models have been tested using 1471 reliable measured base, acid and general base-catalyzed carboxylic acid ester hydrolysis rate constants in water and in mixed solvent systems at different temperatures. In addition, they were tested on 397 reliably measured second order base, acid and general base-catalyzed phosphate ester hydrolysis rate constants over a range of temperatures. The RMS deviation error between predicted and measured values for carboxylic acid ester and phosphate ester compounds was close to the intralaboratory experimental error.

PUBLISHED REPORT	Wasp7 Benthic Algae Model Theory and User's Guide	09/28/2006

AMBROSE, R. B., J. L. MARTIN, AND T. A. WOOL. Wasp7 Benthic Algae Model Theory and User's Guide. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/106 (NTIS PB2007-100139), 2006.
Abstract:	The standard WASP7 eutrophication module includes nitrogen and phosphorus cycling, dissolved oxygen-organic matter interactions, and phytoplankton kinetics. In many shallow streams and rivers, however, the attached algae (benthic algae, or periphyton, attached to submerged substrates) are often of greater importance than phytoplankton. These attached plants affect water quality in various ways, and their impact must often be considered in order to properly evaluate riverine water quality conditions. An advanced WASP7 eutrophication module has been developed to handle streams and rivers with bottom algae. This supplemental user manual documents the new bottom algae algorithms, including the kinetic equations, the additional model input and output, and a series of model verification tests. This advanced WASP7 module, named "periphyton," includes the standard WASP7 eutrophication algorithms, and incorporates bottom algae, with three additional state variables: bottom algal biomass, bottom algal cell nitrogen, and bottom algal cell phosphorus. Bottom algae are not subject to advective and dispersive transport. Sources and sinks include nutrient uptake, growth, nutrient excretion, death, and respiration. Nutrient uptake rates are driven by concentrations of inorganic nitrogen and phosphorus in the water column and within algal cells, and are controlled by cell minimum and half-saturation parameters. Biomass growth is computed from a maximum zero or first-order rate constant that is adjusted internally by water temperature, bottom light intensity, internal nutrient concentrations, and maximum carrying capacity. Nutrient excretion, death, and respiration are represented by first-order, temperature dependent rates. Growth, respiration, and death rates affect other model state variables, including dissolved oxygen and nutrients. The algorithms for predicting bottom algal biomass and nutrient concentrations are based upon the periphyton routines included in the QUAL2K model (Chapra 2005).

PUBLISHED REPORT	Evaluation of the State-of-the-Art Contaminated Sediment Transport and Fate Modeling System	09/28/2006

HAYTER, E. J. Evaluation of the State-of-the-Art Contaminated Sediment Transport and Fate Modeling System. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/108 (NTIS PB2007-100141), 2006.
Abstract:	Modeling approaches for evaluating the transport and fate of sediment and associated contaminants are briefly reviewed. The main emphasis is on: 1) the application of EFDC (Environmental Fluid Dynamics Code), the state-of-the-art contaminated sediment transport and fate public domain modeling system, to a 19-mile reach of the Housatonic River, MA; and 2) the evaluation of a 15-year simulation of sediment and PCB transport and fate in this 19-mile reach. The development of EFDC has been supported by Regions 1 and 4, the Office of Water, the Office of Superfund Remediation Technology Innovation (OSRTI), and the Office of Research and Development (ORD) - NERL/ERD. EFDC is currently being used at the following Superfund sites: Housatonic River, MA; Kalamazoo River, MI; Lower Duwamish Waterway, WA; and Portland Harbor, OR. The evaluation of the modeling results showed that EFDC is capable of simulating the transport and resultant concentrations of TSS and PCBs in this reach of the Housatonic River within specified model performance measures. Specifically, a statistical summary of the performance of the EFDC model for TSS and PCB concentrations found that the relative bias at the downstream boundary of the model domain (i.e., Rising Pond dam) is well within the model performance measure of ± 30% for TSS (-11.93%) and just outside the measure for PCB concentrations (-31.97%). For median relative error, the model performance measure is also ± 30%, and the EFDC model is within the performance measure for both TSS (-27.12%) and PCB (-3.32%) concentrations. Considering the fact that the model was only minimally calibrated, and that the system modeled had widely varying hydraulic and morphologic regimes, the EFDC model's performance, as quantified by relative bias and median relative errors, is considered good. This demonstrates that EFDC is a robust modeling system that can be successfully implemented at other contaminated sediment sites.

PUBLISHED REPORT	Watershed Health Assessment Tools Investigating Fisheries What If Version 2 a Manager's Guide to New Features	09/28/2006

JOHNSTON, J. M. Watershed Health Assessment Tools Investigating Fisheries What If Version 2 a Manager's Guide to New Features. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/109 (NTIS PB2007-100143), 2006.
Abstract:	The Canaan Valley Institute (CVI) is dedicated to addressing the environmental problems in the Mid-Atlantic Highlands (MAH). Their goal is to develop and implement solutions to restore damaged areas and protect aquatic systems. In most wadeable streams of the Mid-Atlantic Highlands region of the eastern United States, habitat alteration resulting from agriculture and development is the primary stressor for fish communities. Sedimentation is the primary source of habitat degradation in Highlands's streams, and productive, sustainable fisheries, i.e., trophy trout streams, are among the valued aquatic endpoints. Planned restoration activities in the region include riparian zone restoration and stream channel design to mitigate near stream inputs and stabilize streambanks. Natural Stream Channel Design (NSCD) is also being investigated by CVI for further optimization of instream habitats for fish communities. Models that predict the responses of fish and stream insect populations and communities to key habitat characteristics are necessary for CVI's watershed management goals, both for determining where to restore and how, as well as evaluating the most probable outcome of various alternatives. The USEPA National Exposure Research Laboratory (NERL) has developed a suite of modeling tools to be used for this purpose. The CVI Watershed Health Assessment Tool Investigating Fisheries, WHAT IF v.2, contains five components: 1) a Regional Prioritization Tool for identifying areas most suitable for riparian restoration and aquaculture; 2) a Hydrologic Tool for predicting hydrologic inputs to streams and bankfull flow; 3) a Clustering Tool for predicting fundamental fish assemblages; 4) a Habitat Suitability Tool for both fishes and benthic insects to relate habitat measures to the suitability of streams for specific species; and 5) the BASS (Bioaccumulation and Aquatic Systems Simulator) model, a generalized aquatic ecosystem simulator to examine fish community dynamics over time. BASS permits the evaluation of comparative risk change due to instream restoration combined with fisheries management. The USEPA Environmental Monitoring and Assessment Program (EMAP) surface water dataset (available online, two index periods in the 1990's) is the basis of the habitat associations derived among fish and insect species and communities.

		ORD Home \| Search EPA \| Search NERL \| Search EIMS \| Contacts \| Help


		EPA Home \| Privacy and Security Notice \| Contact Us Last Updated on Tuesday, October 23, 2007 URL: http://cfpub.epa.gov/ordpubs/nerlpubs/nerlpubs_erd_2006.cfm