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Ecosystems Research Division Publications: 2003

This page lists publication titles, citations and abstracts produced by NERL's Ecosystems Research Division for the year 2003, organized by Publication Type. Your search has returned 144 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
BOOK CHAPTER	Overview of Phytotransformation and Control of Wastes	12/01/2003

MCCUTCHEON, S. C. AND J. L. SCHNOOR. Overview of Phytotransformation and Control of Wastes. Chapter 1, McCutcheon, S.C. and J.L. Schnoor (ed.), Phytoremediation: Transformation and Control of Contaminants. Wiley-Interscience Publishers, 3-58, (2003).
Abstract:	Overview of phytoremediation which is a cost-effective means of managing wastes. Applications are being tested for cleaning up contaminated soil, water, and air.

BOOK CHAPTER	Making Phytoremediation a Successful Technology	12/03/2003

MARMIROLI, N. AND S. C. MCCUTCHEON. Making Phytoremediation a Successful Technology. , Chapter 3, McCutcheon, S.C. and J.L. Schnoor (ed.), Phytoremediation: Transformation and Control of Contaminants. Wiley-Interscience Publishers, 85-119, (2003).
Abstract:	Phytoremediation is becoming a proven technique; soon, the method should be inexpensive, esthetic, and effective for large areas such as urban brownfields.

BOOK CHAPTER	Proof of Phytoremediation for Explosives in Water and Soil	12/01/2003

MCCUTCHEON, S. C., V. F. MEDINA, AND S. L. LARSON. Proof of Phytoremediation for Explosives in Water and Soil. , Chapter 14, McCutcheon, S.C. and J.L. Schnoor (ed.), Phytoremediation: Transformation and Control of Contaminants. Wiley-Interscience Publishers, 429-480, (2003).
Abstract:	Field pilots prove the concept of using created treatment wetlands to restore groundwaters and flooded soils contaminated with explosives.

BOOK CHAPTER	Hydrologic Feasibility Assessment and Design in Phytoremediation	12/01/2003

WEAVER, J. W., S. C. MCCUTCHEON, AND S. L. HUTCHINSON. Hydrologic Feasibility Assessment and Design in Phytoremediation. , Chapter 22, McCutcheon, S.C. and J.L. Schnoor (ed.), Phytoremediation: Transformation and Control of Contaminants. Wiley-Interscience Publishers, 695-716, (2003).
Abstract:	Several design considerations for phytoremediation are based on the capability of trees to remove contaminated water from aquifer.

BOOK CHAPTER	Phytoremediation of Perchlorate	12/01/2003

NZENGUNG, V. A. AND S. C. MCCUTCHEON. Phytoremediation of Perchlorate. , Chapter 29, McCutcheon, S.C. and J.L. Schnoor (ed.), Phytoremediation: Transformation and Control of Contaminants. Wiley-Interscience Publishers, 863-885, (2003).
Abstract:	Perchlorate is taken up from contaminated waters by a variety of plants under a wide range of conditions similar to those observed at contaminated sites.

BOOK CHAPTER	Solar Ultraviolet Radiation and Aquatic Carbon, Nitrogen, Sulfur and Metals Cycles	01/28/2003

Zepp, R. G. Solar Ultraviolet Radiation and Aquatic Carbon, Nitrogen, Sulfur and Metals Cycles. , Chapter 5, E.W. Helbling and H. Zagarese (ed.), UV Effects in Aquatic Organisms and Ecosystems. Royal Society of Chemistry, Cambridge, Uk, 137-183, (2003).
Abstract:	Solar ultraviolet radiation (290-400 nm) has a wide-ranging impact on biological and chemical processes that affect the cycling of elements in aquatic environments. This chapter uses recent field and laboratory observations along with models to assess these impacts on carbon, nitrogen, sulfur and metals cycles. Much emphasis is placed on the interactions of LJV radiation with carbon capture and storage, decomposition, and trace gas exchange. UV exposure generally inhibits phytoplankton photosynthesis and also affects microbial processes both through direct inhibition of bacterial activity as well as through effects on the biological availability of carbon and nitrogen substrates. One important aspect of LJV interactions with carbon cycling involves the formation and decomposition of UV-absorbing organic matter, principally chromophoric dissolved organic matter (CDOM). CDOM controls UV exposure in the sea in many freshwater environments and it can be directly photodecomposed to dissolved inorganic carbon, carbon monoxide, and various carbonyl-containing compounds. UV can potentially affect nitrogen and sulfur cycling in a variety of ways including alterations in nitrogen fixation, effects on the biological availability of dissolved organic nitrogen, UV photoinhibition of organisms such as bacterioplankton and zooplankton that affect sources and sinks of dimethylsulfide (DMS) and UV-initiated photoreactions that oxidize DMS and produce carbonyl sulfide. Metal cycling also interacts in many ways with UV radiation via photoinhibition of microbial redox cycling, direct photoreactions of dissolved metal complexes and of metal oxides and indirect reactions that are mediated by photochemically-produced reactive oxygen species (ROS). Photoreactions can affect the biological availability of essential trace nutrients such as iron and manganese, transforming the metals from complexes that are not readily assimilated to free metal ions or metal hydroxides that are available.

JOURNAL	Using Rotifer Population Demographic Parameters to Assess Impacts of the Degradation Products from Trinitrotoluene Phytoremediation	06/01/2003

Hitchcock, D. R., S. C. McCutcheon, AND M. C. Smith. Using Rotifer Population Demographic Parameters to Assess Impacts of the Degradation Products from Trinitrotoluene Phytoremediation. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 55(2):143-151, (2003).
Abstract:	The objective of this study was to evaluate the aquatic chronic lethal and sublethal toxicity effects from the phytoremediation of water contaminated with 2,4,6-trinitrotoluene (2,4,6-TNT) by the wetland plant species Myriophyllum aquaticum (parrot feather). Rotifers (Brachionus calyciflorus) fed with an algal species (Nannochloropsis spp.) were used as aquatic test populations. Continuous flow laboratory microcosms were used to determine effects on rotifer populations by 2,4,6-TNT and the primary degradation product amino-dinitrotoluene (ADNT) during and after phytoremediation. Rotifer demographic parameters from life tables, including survivorship, fecundity, reproductive values, net reproductive rate, generation time, intrinsic growth rate, and life expectancy, were used as measures of treatment effects. High performance liquid chromatography (HPLC) analyses were performed to determine nitroaromatic concentrations. Results from this study show significant differences in rotifer demographic parameters between microcosms with elevated initial 2,4,6-TNT concentrations. Significant differences in demographic parameters also existed between microcosms that did and did not receive phytoremediation treatment and control microcosms. This study shows that TNT phytoremediation via artificial wetlands may not only clean up hazardous waste at munitions sites, but also encourage the growth of aquatic populations such as rotifers.

JOURNAL	Cosolvent Effects on Phenanthrene Sorption-Desorption on a Fresh-Water Sediment	04/01/2003

Bouchard, D. C. Cosolvent Effects on Phenanthrene Sorption-Desorption on a Fresh-Water Sediment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 22(4):736-740, (2003).
Abstract:	This study evaluated the effects of the water-miscible cosolvent methanol on the sorption-desorption of phenanthrene by the natural organic matter (NOM) of a fresh-water sediment. A biphasic pattern was observed in the relationship between the log of the carbon-normalized sorption distribution coefficient (Koc) and the volumetric fraction of methanol (fc) that was accounted for with phenanthrene solubility data. Results also indicated that methanol elicited additional effects on phenanthrene sorption beyond the solution phase effects. The level of fc was observed to have a significant effect on sorption-desorption hysteresis, with hysteresis being greater for treatments where phenanthrene and sediment were equilibrated with methanol-phenanthene solutions, but desorbed with aqueous solutions. These results are discussed in light of the deformable pore network of the rubbery-glassy NOM polymer construct.

JOURNAL	Reductive Dehalogenation of Halomethanes in Iron-and Sulfate-Reducing Sediments. 1. Reactivity Pattern Analysis	02/15/2003

Kenneke, J. F. AND E. J. Weber. Reductive Dehalogenation of Halomethanes in Iron-and Sulfate-Reducing Sediments. 1. Reactivity Pattern Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 37(4):713-720, (2003).
Abstract:	The incorporation of reductive transformations into environmental fate models requires the characterization of natural reductants in well-characterized sediments and aquifer materials. For this purpose, reactivity patterns (i.e., the range and relative order of reactivity) for a series of halogenated methanes were measured in an iron- and sulfate reducing sediment, as well as model systems representing iron sulfide and Fe(II) associated with Fe(III) containing minerals. The strong similarity in reaction patterns between the iron- and sulfate-reducing sediments suggests a common mechanism for reductive transformation. The comparison of reactivity patterns measured in the sediment and model systems, in addition to those reported for the reduction of halogenated methanes in iron porphyrin and mercaptojuglone model systems, suggests that Fe(II) adsorbed to Fe(III) containing minerals is the dominant reductant in both the iron- and sulfate-reducing sediments despite the significant formation of FeS.

JOURNAL	Application of Aquatox, a Process-Based Model for Ecological Assessment, to Contentnea Creek in North Carolina	12/01/2003

Rashleigh, B. Application of Aquatox, a Process-Based Model for Ecological Assessment, to Contentnea Creek in North Carolina. JOURNAL OF FRESHWATER ECOLOGY 18(4):515-522, (2003).
Abstract:	The aquatic ecosystem simulation model AQUATOX was parameterized and applied to Contentnea Creek in the coastal plain of North Carolina to determine the response of fish to moderate levels of physical and chemical habitat alterations. Biomass of four fish groups was most sensitive to temperature and detritus, but showed little sensitivity to changes in nutrients, sediment, pH, or dissolved oxygen. The model appears useful for assessment of stream ecosystem response to certain types of stressors; its utility should be determined further by model applications in other study areas and ecoregions.

JOURNAL	Methodologies for Calibration and Predictive Analysis of a Watershed Model	04/15/2003

Doherty, J. AND J. M. Johnston. Methodologies for Calibration and Predictive Analysis of a Watershed Model. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 39(2):251-265, (2003).
Abstract:	The use of a fitted-parameter watershed model to address water quantity and quality management issues requires that it be calibrated under a wide range of hydrologic conditions. However, rarely does model calibration result in a unique parameter set. Parameter nonuniqueness can lead to predictive nonuniqueness. The extent of model predictive uncertainty should be investigated if management decisions are to be based on model projections. Using models built for four neighboring watersheds in the Neuse River Basin of North Carolina, the application of the automated parameter optimization software PEST in conjunction with the Hydrologic Simulation Program Fortran (HSPF) is demonstrated. Parameter nonuniqueness is illustrated, and a method is presented for calculating many different sets of parameters, all of which acceptably calibrate a watershed model. A regularization methodology is discussed in which models for similar watersheds can be calibrated simultaneously. Using this method, parameter differences between watershed models can be minimized while maintaining fit between model outputs and field observations. In recognition of the fact that parameter nonuniqueness and predictive uncertainty are inherent to the modeling process, PEST's nonlinear predictive analysis functionality is then used to explore the extent of model predictive uncertainty.

JOURNAL	Use of Pretreatment Zones and Zero-Valent Iron for the Remediation of Chloroalkenes in An Oxic Aquifer	05/15/2003

Kenneke, J. F. AND S. C. McCutcheon. Use of Pretreatment Zones and Zero-Valent Iron for the Remediation of Chloroalkenes in An Oxic Aquifer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 37(12):2829-2835, (2003).
Abstract:	Pre-treatment zones (PTZs) composed of sand, 10% zero-valent iron [Fe(0)]/sand, and 10% pyrite (FeS2)/sand were examined for their ability to prolong Fe(0) reactivity in aboveground column reactors and a subsurface permeable reactive barrier (PRB). The test site had an acidic, oxic aquifer contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). The 10% FeS2 and 10% Fe(0) PTZs removed dissolved oxygen and affected the pH and Eh in the PTZ. None of the PTZs had any effect on pH or Eh in the 100% Fe(0) zone. Nitrate and sulfate were removed more quickly in the Fe(0) zones preceded by either the 10% Fe(0) PTZ or 10% FeS2. PCE first-order degradation rate constants (kobs) decreased significantly (>80%) with increasing column pore volumes regardless of the PTZ material used. kobs finally leveled off after approximately one year of operation. The column results predict that the PRB will experience a breakthrough of PCE in 3-5 years and illustrates the importance of incorporating temporal variations in degradation rate constants when designing PRBs.

JOURNAL	Stable Carbon Isotope Ratio and Composition of Microbial Fatty Acids in Tropical Soils	01/03/2003

Burke Jr., R. A., M. Molina, J. E. Cox, L. J. Osher, AND M. C. Piccolo. Stable Carbon Isotope Ratio and Composition of Microbial Fatty Acids in Tropical Soils. JOURNAL OF ENVIRONMENTAL QUALITY 32(1):198-206, (2003).
Abstract:	The soil microbial community plays a critical part in tropical ecosystem functioning through its role in the soil organic matter (SOM) cycle. This study evaluates the relative effects of soil type and land use on: (1) soil microbial community structure and (2) the contribution of SOM derived from the original forest vegetation to the functioning of pasture and sugarcane ecosystems. We used principal components analysis (PCA) of soil phospholipid fatty acid (PLFA) profiles to evaluate microbial community structure and PLFA stable carbon isotope ratios (d13C) as indicators of the d13C of microbial substrates. Soil type mainly determined the relative proportions of gram positive versus gram negative bacteria whereas land use primarily determined the relative proportion of fungi, protozoa, and actinomycetes versus other types of microorganisms. Application of a simple model to our PLFA d13C data from land use chronosequences indicates that forest derived SOM is actively cycled for appreciably longer times in sugarcane ecosystems developed on Andisols (mean turnover time = 50 years) than in sugarcane ecosystems developed on an Oxisol (mean turnonver time = 13 years). Our analyses indicate that soil chronosequence PLFA d13C measurements can be useful indicators of the contribution that SOM derived from the original vegetation makes to continued ecosystem function under the new land use.

JOURNAL	Estimation of Surplus Biomass of Clupeids in Smith Mountain Lake, Virginia	03/31/2003

Cyterski, M. J., J. Ney, AND M. Duval. Estimation of Surplus Biomass of Clupeids in Smith Mountain Lake, Virginia. TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY 132(2):361-370, (2003).
Abstract:	Mean annual estimates of surplus biomass of alewife Alosa pseudoharengus and gizzard shad Dorosoma cepedianum in Smith Mountain Lake, Virginia, were calculated using data on the biomass, growth, and mortality of each clupeid species. Surplus biomass, defined as production over a time period, less the difference between biomass at the end and beginning of the time period, was determined for each cohort of both prey species. Mean total alewife biomass estimated from hydroacoustic surveys during 1993-1998 was 37 kg/ha. Mean total gizzard shad cove rotenone biomass from 1990-1997 was 89 kg/ha. Coupling biomass with estimated growth and mortality rates, mean annual alewife and gizzard shad surplus biomass, summed across all cohorts, was 74 kg/ha and 116 kg/ha, respectively. The surplus biomass of alewife barely meets piscivore demand (primarily largemouth bass Micropterus salmoides and striped bass Morone saxatilis) while predator demand might exceed gizzard shad surplus biomass when prey availability is taken into account.

JOURNAL	Book Review of "ECOLOGICAL Effects of Roads"	06/02/2003

Bird, S. L. Book Review of "ECOLOGICAL Effects of Roads". JOURNAL OF ENVIRONMENTAL QUALITY 32(3):1151, (2003).
Abstract:	Throughout the world, roads have become a permanent part of our environment. The ecological effects of roads and traffic are as consequential as other topical issues such as losses in biological diversity and damage by exotic and invasive species. However, this issue has usually received less attention from environmental managers, ecologists, and the public in general. Roadways impact ecological function through a variety of mechanisms from vehicular mortality of wildlife to hydrologic alterations. The effects of roads are incremental and cascading-roads lead to more roads and other development. This book discusses the biology of roads and roadside verges, describes the effects of roads and traffic, and discusses methods for mitigating the adverse effects of roads on the environment. This book aims to be a practical guide to the general issues and solutions for the ecological impacts of roads.

JOURNAL	Enantioseparation of Malathion, Cruformate, and Fensulfothion Organosphosphorus Pesticides By Mixed-Mode Electrokinetic Capillary Chromatography	02/15/2003

Anigbogu, V., H. Woldeab, A. W. Garrison, AND J. Avants. Enantioseparation of Malathion, Cruformate, and Fensulfothion Organosphosphorus Pesticides By Mixed-Mode Electrokinetic Capillary Chromatography. INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY 83(2):89-100, (2003).
Abstract:	Mixed-mode electrokinetic capillary chromatography (mixed-ECC) has been used for the enantioseparation of organophosphorus pesticides. In mixed-ECC, a combination of three pseudostationary phases including surfactants, neutral, and charged cyclodextrins, are used to resolve very challenging enantioseparation problems. The conditions mimic a mixture of micellar electrokinetic capillary chromatography (MECC) and dual-cyclodextrin electrokinetic capillary chromatography (dual-CECC) conditions. In this work SDS, carboxymethyl- -CD, hydroxypropyl-BCD, and organic modifiers were mixed at various concentrations in order to achieve enantioseparation of three organophosphorus pesticides- cruformate (ruelene), malathion, and fensulfothion. The best condition for separation of ruelene enantiomers was by using a mixture of 70 mM SDS/15 mM carboxymethyl-BCD/45 mM hydroxypropyl-BCD/20 % (v/v) acetonitrile in 20 mM borate buffer at pH 8.6, applied voltage of 25 kV at 25oC. Malathion enantiomers were successfully resolved using either 10 mM SDS/50 mM CM-BCD/40 mM hydroxypropyl-BCD or 50 mM CM-BCD/50 mM hydroxypropyl-BCD/20% (v/v) methanol in 20 mM borate buffer. Fensulfothion enantiomers were successfully resolved using a mixture of 75 mM SDS/12.5 mM carboxymethyl-BCD/45 mM hydroxypropyl-BCD in the same 20 mM borate buffer. The results demonstrate the versatility of the mixed-mode electrokinetic capillary chromatography (mixed mode ECC) technique in handling very difficult separations such as the organophosphoramidates. It offers options for selectivity control by combining three or more pseudostationary phases in the background electrolyte (BGE). The approach to optimization in mixed-mode ECC is generally more straightforward than the use of a solid stationary phases(s) in HPLC. In theory, the separation selectivity of such mixed-ECC system can be modified to the extremes of MECC and the dual-CECC of the chiral selectors.

JOURNAL	Interactive Effects of Ozone Depletion and Climate Change on Biogeochemical Cycles	01/15/2003

Zepp, R. G., T. V. Callaghan, AND D. J. ERICKSON. Interactive Effects of Ozone Depletion and Climate Change on Biogeochemical Cycles. PHOTOCHEMICAL AND PHOTOBIOLOGICAL SCIENCES 2(1):51-61, (2003).
Abstract:	The effects of ozone depletion on global biogeochemical cycles, via increased UV-B radiation at the Earth's surface, have continued to be documented over the past 4 years. In this report we also document various effects of UV-B that interact with global climate change because the detailed interactions between ozone depletion and climate change are central to the prediction and evaluation of future Earth environmental conditions. There is increasing evidence that elevated UV-B has significant effects on the terrestrial biosphere with important implications for the cycling of carbon, nitrogen and other elements. Increased UV has been shown to induce carbon monoxide production from dead plant matter in terrestrial ecosystems, nitrogen oxide production from Arctic and Antarctic snowpacks, and halogenated substances from several terrestrial ecosystems. New studies on UV effects on the decomposition of dead leaf material confirm that these effects are complex and species-specific. Decomposition can be retarded, accelerated or remain unchanged. It has been difficult to relate effects of UV on decomposition rates to leaf litter chemistry, as this is very variable. However, new evidence shows UV effects on some fungi, bacterial communities and soil fauna that could play roles in decomposition and nutrient cycling. An important new result is that not only is nitrogen cycling in soils perturbed significantly by increased UV-B, but that these effects persist for over a decade. As nitrogen cycling is temperature dependent, this finding clearly links the impacts of ozone depletion to the ability of plants to use nitrogen in a warming global environment. There are many other potential interactions between UV and climate change impacts on terrestrial biogeochemical cycles that remain to be quantified. There is also new evidence that UV-B strongly influences aquatic carbon, nitrogen, sulfur, and metals cycling that affect a wide range of life processes. UV-B accelerates the decomposition of colored dissolved organic matter (CDOM) entering the sea via terrestrial runoff, thus having important effects on oceanic carbon cycle dynamics. Since UV-B influences the distribution of CDOM, there is an impact of UV-B on estimates of oceanic productivity based on remote sensing of ocean color. Thus, oceanic productivity estimates based on remote sensing require estimates of CDOM distributions. Recent research shows that UV-B transforms dissolved organic matter to dissolved inorganic carbon and nitrogen, including carbon dioxide and ammonium and to organic substances that are either more or less readily available to micro-organisms. The extent of these transformations is correlated with loss of UV absorbance by the organic matter. Changes in aquatic primary productivity and decomposition due to climate-related changes in circulation and nutrient supply, which occur concurrently with increased UV-B exposure, have synergistic influences on the penetration of light into aquatic ecosystems. New research has confirmed that UV affects the biological availability of iron, copper and other trace metals in aquatic environments thus potentially affecting the growth of phytoplankton and other microorganisms that are involved in carbon and nitrogen cycling. There are several instances where UV-B modifies the air-sea exchange of trace gases that in turn alter atmospheric chemistry, including the carbon cycle.

JOURNAL	Prediction of the Vapor Pressure, Boiling Point, Heat of Vaporization and Diffusion Coefficient of Organic Compounds	08/08/2003

Hilal, S. H., S. W. Karickhoff, AND L. A. Carreira. Prediction of the Vapor Pressure, Boiling Point, Heat of Vaporization and Diffusion Coefficient of Organic Compounds. QSAR & COMBINATORIAL SCIENCE 22(6):565-574, (2003).
Abstract:	The prototype computer program SPARC has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC solute-solute physical process models have been developed and tested for vapor pressure (at any temperature), heat of vaporization (at 25C and the boiling point), diffusion coefficient (at 25C) and boiling point (at any pressure) for a relatively large number of organic molecules. The RMS deviation error of the predicted the vapor pressures, heats of vaporization (at any temperature) and boiling points (at any pressure) were close to the intralaboratory experimental errors.

JOURNAL	Changes in Enantiomeric Fractions During Microbial Reductive Dechlorination of Pcb132, Pcb149, and Aroclor 1254 in Lake Hartwell Sediment Microcosms	03/15/2003

Pakdeesusuk, U., W. J. Jones, C. M. Lee, A. W. Garrison, W. L. O'Niell, D. L. Freedman, J. T. Coates, AND C. S. Wong. Changes in Enantiomeric Fractions During Microbial Reductive Dechlorination of Pcb132, Pcb149, and Aroclor 1254 in Lake Hartwell Sediment Microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 37(6):1100-1107, (2003).
Abstract:	Enantioselectivity of microbial reductive dechlorination of chiral PCBs in sediments from Lake Hartwell, SC, was determined by microcosm studies and enantiomer-specific GC analysis. Sediments from two locations in the vicinity of the highest levels of PCB contamination were used as inocula. Dechlorination activity was monitored by concentration decreases in the spiked chiral PCBs and formation of dechlorination products using both achiral and chiral chromatography. Live microcosms spiked with PCB132 (234-236) exhibited dechlorination of PCB132 to PCB91 (236-24) and PCB51 (24-26). Meta-dechlorination was the dominant mechanism. Microcosms spiked with PCB149 (245-236) exhibited preferential para-dechlorination of PCB149 to PCB95 (236-25), followed by meta-dechlorination to PCB53 (25-26) and subsequently PCB19 (26-2). Dechlorination of chiral PCB132 and PCB149 was not enantioselective. In Aroclor 1254-spiked microcosms, reductive dechlorination of PCB149 also was non-enantioselective. These results suggest that dechlorinating enzymes responsible for dehalogenation of the chiral PCB132 and PCB149 congeners bind both enantiomers equally. Reductive dechlorination of PCB91 and PCB95, however, occurred in an enantioselective manner indicating that the dechlorinating enzymes for these PCBs are enantiomer-specific. The chlorine substitution pattern on the biphenyl ring appears to influence whether reductive dechlorination of chiral PCB congeners is enantioselective. Enantioselective PCB dechlorination by the microbial population of Lake Hartwell sediments occurs for select chiral PCBs; thus, certain chiral PCBs may be useful as markers for in situ reductive dechlorination. These results represent the first evidence of stereoselective reductive dechlorination of PCBs under controlled conditions.

JOURNAL	H2 Consumption During the Microbial Reductive Dehalogenation of Chlorinated Phenols and Tetrachloroethene	08/15/2003

Jones, W. J., C. S. Mazur, AND C. L. TebesStevens. H2 Consumption During the Microbial Reductive Dehalogenation of Chlorinated Phenols and Tetrachloroethene. BIODEGRADATION 14(4):285-295, (2003).
Abstract:	Competition for molecular hydrogen exists among hydrogen-utilizing microorganisms in anoxic environments, and evidence suggests that lower hydrogen concentrations are observed with more energetically favorable electron-accepting processes. The transfer of electrons to organochlorines via reductive dehalogenation reactions plays an important role in hydrogen dynamics in impacted systems. We studied the flux of aqueous hydrogen concentrations in methanogenic sediment microcosms prior to and during reductive dehalogenation of a variety of substituted chlorophenols (CP) and tetrachloroethene (perchloroethylene, PCE). Mean hydrogen concentrations during reductive dehalogenation of 2,4-CP, 2,3,4-CP, and PCP were 3.6 nM, 4.1 nM, and 0.34 nM, respectively. Sediment microcosms that were not dosed with chlorophenols yet were actively methanogenic maintained a significantly higher mean hydrogen concentration of 9.8 nM. During active PCE dehalogenation, sediment microcosms maintained a mean hydrogen concentration of 0.82 nM. These data indicate that during limiting hydrogen production, the threshold ecosystem hydrogen concentration is controlled by microbial populations that couple hydrogen oxidation to thermodynamically favorable electron accepting reactions, including reductive dehalogenation of chloroaromatic compounds. We also present revised estimates for the Gibbs free energy available from the reductive dehalogenation of a variety of substituted chlorophenols based on recently published values of vapor pressure, solubility, and pKa for these compounds.

JOURNAL	The Emergence of Ecological Engineering as a Discipline	10/15/2003

Gattie, D. K., E. W. Tollner, M. C. Smith, AND S. C. McCutcheon. The Emergence of Ecological Engineering as a Discipline. ECOLOGICAL ENGINEERING 20(5):409-420, (2003).
Abstract:	Pioneering efforts in the field of ecological engineering research and practice have proven to be tremendous strides toward establishing a new engineering discipline with a science base in ecology. Case studies, demonstrations and applications pertaining to restoration, rehabilitation, conservation, sustainability, reconstruction, remediation and reclamation of ecosystems using ecological engineering techniques are numerous. This has brought the field to the current level where many scientists and engineers adequately support the concept of, and need for, ecological engineering, and generally agree that ecological engineering has been sufficiently defined. There is also general agreement that its emergence as an engineering discipline remains a difficult task. This paper discusses certain general characteristics of existing engineering disciplines that can guide the emergence of ecological engineering. The authors then propose and discuss three concepts: 1) certification in ecological design, 2) development of core ecological engineering sciences and 3) establishment of formal ecological engineering areas of research, as elements of a formal approach to emerge ecological engineering as a principled, quantitative, novel, formal and recognized engineering discipline that coalesces past, current and future outputs of research and practice into cohesive underpinnings for the field.

JOURNAL	Accumulation of Perchlorate in Tobacco Plants: Development of a Plant Kinetic Model	05/12/2003

Sundberg, S. E., J. J. Ellington, J. J. Evans, D. Keys, AND J. W. Fisher. Accumulation of Perchlorate in Tobacco Plants: Development of a Plant Kinetic Model. JOURNAL OF ENVIRONMENTAL MONITORING 5(3):505-512, (2003).
Abstract:	Previous studies have shown that tobacco plants are tolerant of perchlorate and will accumulate perchlorate in plant tissues. This research determined the uptake, translocation, and accumulation of perchlorate in tobacco plants. Three hydroponics growth studies were completed under greenhouse conditions. Depletion of perchlorate in the hydroponics nutrient solution and accumulation of perchlorate in plant tissues were determined at two-day intervals using ion chromatography. Perchlorate primarily accumulated in tobacco leaves, yielding a substantial storage capacity for perchlorate. Mass balance results show that perchlorate degradation was negligible in plants. Tobacco plants were show to effectively accumulate perchlorate over a wide range of initial concentrations (10 ppb to 100 ppm) from the hydroponics solution. Results suggest that tobacco plants are potential plants for the phytoremediation of perchlorate. A mathematical model was developed to describe the distribution of perchlorate in tobacco plants under rapid growth conditions. The distribution of inorganic chemicals such as perchlorate has not been modeled previously. The Plant Kinetic (PK) model defined a plant as a set of compartments, described by mass balance differential equations and plant-specific physiological parameters. Data obtained from a separate hydroponics growth study with multiple solution perchlorate concentrations were used to validate predicted root, stem, and leaf concentrations. There was good agreement between model predictions and measured concentrations in the plant. The model, once adequately validated, can be applied to other terrestrial plants and inorganic chemicals currently used for both phytoremediation and ecological risk assessment.

JOURNAL	Tribromopyrrole, Brominated Acids, and Other Disinfection Byproducts Produced By Disinfection of Drinking Water Rich in Bromide	09/01/2003

Richardson, S. D., A. D. Thruston Jr., C. RavAcha, L. Groisman, I. Popilevsky, O. Juraev, V. Glezer, B. McKague, M. J. Plewa, AND E. D. Wagner. Tribromopyrrole, Brominated Acids, and Other Disinfection Byproducts Produced By Disinfection of Drinking Water Rich in Bromide. ENVIRONMENTAL SCIENCE & TECHNOLOGY 37(17):3782-3793, (2003).
Abstract:	Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comprehensive investigation of DBPs formed by chlorine dioxide under high bromide conditions. Drinking water from full scale treatment plants in Israel was studied, along with source water (Sea of Galilee) treated under carefully controlled laboratory conditions. Select DBPs (trihalomethanes, haloacetic acids, aldehydes, chlorite, chlorate, and bromate) were quantified. Many of the DBPs identified have not been previously reported, and several of the identifications were confirmed through the analysis of authentic standards. Elevated bromide levels in the source water caused a significant shift in speciation to bromine-containing DBPs, bromoform and dibromoacetic acid were the dominant DBPs observed, with very few chlorine-containing compounds found. Iodo-trihalomethanes were also identified, as well as a number of new brominated carboxylic acids and 2,3,5-tribromopyrrole, which represents the first time a halogenated pyrrole has been reported as a DBP. Most of the bromine-containing DBPs were formed during pre-chlorination at the initial reservoir, and were not formed by chlorine dioxide itself. An exception was the iodo-THMs, which appeared to be formed by a combination of chlorine dioxide with chloramines or chlorine (either added deliberately or as an impurity in the chlorine dioxide). A separate laboratory study was also conducted to quantitatively determine the contribution of fulvic acids and humic acids (from isolated natural organic matter in the Sea of Galilee) as precursor material to several of the DBPs identified. Results showed that fulvic acid plays a greater role in the formation of THMs, haloacetic acids, and aldehydes, but 2,3,5-tribromopyrrole was produced primarily from humic acid. Because this was the first time a halopyrrole has been identified as a DBP, 2,3,5-tribromopyrrole was tested for mammalian cell cytotoxicity and genotoxicity. In comparison to other DBPs, 2,3,5-tribromopyrrole was 8X, 4.5X, and 16X more cytotoxic than dibromoacetic acid, 3-chloro-4-(dichloromethyl)-5-hydroxy-2-[5H]-furanone [MX], or potassium bromate. 2,3,5-Tribromopyrrole also induced acute genomic damage, with a genotoxic potency (299 M) similar to that of MX.

JOURNAL	Quantitative Structure-Activity Relationships for Chemical Reductions of Organic Contaminants	08/15/2003

Tratnyek, P. G., E. J. Weber, AND R. P. Schwarzenbach. Quantitative Structure-Activity Relationships for Chemical Reductions of Organic Contaminants. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 22(8):1733-1742, (2003).
Abstract:	Sufficient kinetic data on abiotic reduction reactions involving organic contaminants are now available that quantitative structure-activity relationships (QSARs) for these reactions can be developed. Over 50 QSARs have been reported, most in just the last few years, and they are summarized as a group here. The majority of these QSARs concern dechlorination reactions, and most of the rest concern nitro reduction reactions. Most QSARs for reduction reactions have been developed mainly as diagnostic tools for determining reduction mechanisms and pathways. So far, only a few of these QSARs are sufficiently precise in formulation, yet general in scope, that they might be useful for predicting contaminant fate. Achieving the goal of developing predictive models for the kinetics of contaminant reduction in the environment will require a delicate balance between process-level rigor and practical levels of approximation.

JOURNAL	Water Analysis: Emerging Contaminants and Current Issues	06/15/2003

Richardson, S. D. Water Analysis: Emerging Contaminants and Current Issues. ANALYTICAL CHEMISTRY 75(12):2831-2857, (2003).
Abstract:	This review covers developments in Water Analysis over the period of 2001-2002. A few significant references that appeared between January and February 2003 are also included. Previous Water Analysis reviews have been very comprehensive; however, in 2001, Analytical Chemistry changed its approach to include only 100-200 significant references and to mainly focus on new trends. As a result, this year the review will limit its focus to new, emerging contaminants and environmental issues that are driving most of the current research. Even with this 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 only discuss representative papers in the areas of focus.

JOURNAL	Disinfection By-Products and Other Emerging Contaminants in Drinking Water	11/01/2003

Richardson, S. D. Disinfection By-Products and Other Emerging Contaminants in Drinking Water. TRENDS IN ANALYTICAL CHEMISTRY 22(10):666-684, (2003).
Abstract:	Although drinking water disinfection by-products (DBPs) have been studied for the last 30 years, significant, new concerns have arisen. These concerns include adverse reproductive and developmental effects recently observed in human populations, concerns that the types of cancer observed in laboratory animals (for regulated DBPs) do not correlate with the cancers observed in human populations (indicating that other DBPs may be important), and concerns arising from human exposure studies that show that other routes besides ingestion (i.e., inhalation and dermal adsorption) are also significant sources of DBP exposures. In addition, many drinking water utilities are changing their primary disinfectant from chlorine to alternative disinfectants (e.g., ozone, chlorine dioxide, and chloramines), which generally reduce regulated trihalomethane and haloacetic acid levels, but can increase the levels of other potentially toxicologically important DBPs. For example, results of a new U.S. nationwide DBP occurrence study (discussed in this review) demonstrated that bromo-trihalonitromethanes, iodo-trihalomethanes, dihaloaldehydes, MX (MX is 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone), and brominated forms of MX were formed at higher levels when alternative disinfectants were used to treat drinking water. Specific DBPs of emerging toxicological interest include brominated and iodinated compounds including bromonitromethanes, iodo-trihalomethanes, iodo-acids, and brominated forms of MX--as well as nitrosodimethylamine (NDMA). In addition to DBPs, there are also new concerns over the presence of pharmaceuticals, organotins, methyl-tert-butyl ether (MTBE), perchlorate, and algal toxins in drinking water. This article will discuss these drinking water contaminants of emerging concern and the analytical methods currently being used for their determination.

JOURNAL	An Exact Method for Relating Zwitterionic Microscopic to Macroscopic Acidity Constants	07/15/2003

Loux, N. T. An Exact Method for Relating Zwitterionic Microscopic to Macroscopic Acidity Constants. CHEMICAL SPECIATION AND BIOAVAILABILITY 15(2):47-51, (2003).
Abstract:	Zwitterions are aqueous solvated molecules simultaneously possessing one negatively and one positively charged site. Although electroneutral, the environmental interaction of zwitterions with other ionic species is likely to differ significantly from the behavior of comparable electroneutral species without charged sites. Amino acids, the zwitterionic species that have received the most historical scrutiny, are believed to possess at least four microscopic acidity constants: ka = [H+] [+H3NRCOO-]/[+H3NRCOOH], kb = [H+] [H2NRCOOH]/[+H3NRCOOH], kc = [H+] [H2NRCOO-]/[+H3NRCOO-], and kd = [H+] [H2NRCOO-]/[H2NRCOOH]. Unfortunately, due to their comparable energetics, these microscopic acidity constants cannot be discerned using standard potentiometric titration procedures. In response, experimentally observable macroscopic constants (K1 and K2) have historically been related to the microscopic constants with the following relationships: K1 = ka + kb and 1/K2 = 1/kc + kd. It will be demonstrated that these equations are approximations suitable for restricted pH ranges and that more exact expressions can be derived: K1 = ka + kb + kcka/[H+] + kdkb/[H+] and 1/K2 = 1/kd + 1/kc + [H+]/kakc + [H+]/kbkd.

JOURNAL	Moditoring What Would It Look Like?	11/15/2003

Burns, L. A. Moditoring What Would It Look Like? UPDATE: STONE ENVIRONMENTAL NEWS ON FIFRA AND ENVIRONMENTAL FATE ISSUES (Fall 2003):2-3, (2003).
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

JOURNAL	Sage Analysis of Transcriptome Responses in Arabidopsis Roots Exposed to 2,4,6-Trinitrotoluene	11/01/2003

Ekman, D. R., W. W. Lorenz, A. E. Przybyla, N. L. Wolfe, AND J. D. Dean. Sage Analysis of Transcriptome Responses in Arabidopsis Roots Exposed to 2,4,6-Trinitrotoluene. PLANT PHYSIOLOGY 133(3):1397-1406, (2003).
Abstract:	Serial Analysis of Gene Expression (SAGE) was used to profile transcript levels in Arabidopsis thaliana roots and assess their responses to 2,4,6-trinitrotoluene (TNT) exposure. SAGE libraries representing control and TNT-exposed seedling root transcripts were constructed, and each was sequenced to a depth of roughly 32,000 tags. More than 19,000 unique tags were identified overall. The second most highly induced tag (27-fold increase) represented a glutathione S-transferase. Cytochrome P450 enzymes, as well as an ABC transporter and a probable nitroreductase, were highly induced by TNT exposure. Analyses also revealed an oxidative stress response upon TNT exposure. Although some increases were anticipated in light of current models for xenobiotic metabolism in plants, evidence for unsuspected conjugation pathways was also noted. Identifying transcriptome-level responses to TNT exposure will better define the metabolic pathways plants use to detoxify this xenobiotic compound, which should help improve phytoremediation strategies directed at TNT and other nitroaromatic compounds.

JOURNAL	A Review and Comparison of Models for Predicting Dynamic Chemical Bioconcentration in Fish	09/15/2003

Barber, M. C. A Review and Comparison of Models for Predicting Dynamic Chemical Bioconcentration in Fish. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 22(9):1963-1992, (2003).
Abstract:	Over the past 20 years, a variety of models have been developed to simulate the bioconcentration of hydrophobic organic chemicals by fish. These models differ not only in the processes they address but also in the way a given process is described. Processes described by these models include chemical diffusion through the gill's interlamellar water, epithelium, and lamellar blood plasma; advective chemical transport to and from the gill by ventilation and perfusion, respectively; and internal chemical deposition by thermodynamic partitioning to lipid and other organic phases. This article reviews the construction and associated assumptions of 10 of the most widely cited fish bioconcentration models. These models are then compared with respect to their ability to predict observed uptake and elimination rates using a common database for those model parameters that they have in common. Statistical analyses of observed and predicted exchange rates reveal that rates predicted by these models can be calibrated almost equally well to observed data. This fact is independent of how well any given model is able to predict observed exchange rates without calibration. The importance of gill exchange models and how they might be improved are also discussed.

JOURNAL	Tribromopyrrole Its Appearance in the Environment	12/30/2003

Glezer, V., O. Juraev, AND S. D. Richardson. Tribromopyrrole Its Appearance in the Environment. CHEMISTRY OF HETEROCYCLIC COMPOUNDS 39(12):1647-1648, (2003).
Abstract:	Disinfection of drinking water has been used approximately 100 years, but only since the 1970s has the formation of hazardous products during this process been investigated. Concern for the potential human health hazards associated with chlorinated drinking water has been heightened by the widespread recognition of mutagenic activity exhibited by disinfection by-products (DBPs). More than 500 DBPs have been reported, mainly aliphatic and partly aromatic compounds, with very little information about heterocyclic compounds. The detailed study of DPBs formed by disinfection of one of the main Israel drinking water sources - the Sea of Galille (or Lake Kinereth) was carried out. The main peculiarity of this water is a very high bromide ion content: ~2 mg/L.

JOURNAL	Distribution of PCB 84 Enantiomers in C57bl/6 Mice	03/15/2003

Lehmler, H. J., D. J. Price, A. W. Garrison, W. J. Birge, AND L. W. Robertson. Distribution of PCB 84 Enantiomers in C57bl/6 Mice. FRESENIUS ENVIRONMENTAL BULLETIN 12(2):254-260, (2003).
Abstract:	Nineteen of the 209 possible PCB congeners exist as pairs of stable rotational isomers that are enantiomeric to each other. A racemic mixture of PCB atropisomers is present in technical PCB mixtures, thus raising concerns about enantioselective distribution, metabolism, and disposition of these congeners. We investigated the distribution and enantiomeric fractions (EF) of PCB 84 in untreated female C57B1/6 mice. PCB 84 was injected intraperitoneally with 600 mumol/kg body weight, and the EFs were determined by chiral gas chromatography in the liver, brain, lung, heart, spleen and kidney after three or six days. The EFs in brain, liver, lung and heart were significantly different from the racemic PCB 84 standard at days three and six, with an enrichment of (+)-PCB 84 in all four tissues. A significant enrichment of (+)-PCB 84 in the kidney was observed for day six. No significant difference was observed for the spleen on both time points. Tissue EFs for the brain showed the highest EF, whereas the EFs in the spleen were almost identical with the PCB 84 standard. The EFs did not change significantly between day three and six, suggesting that the differential distribution of (+)-PCB 84 may primarily occur during the initial distribution phase.

JOURNAL	Role of the Photo-Fenton Reaction in the Production of Hydroxyl Radicals and Photobleaching of Colored Dissolved Organic Matter in a Coastal River of the Southeastern United States	12/15/2003

White, E. M., P. P. Vaughan, AND R. G. Zepp. Role of the Photo-Fenton Reaction in the Production of Hydroxyl Radicals and Photobleaching of Colored Dissolved Organic Matter in a Coastal River of the Southeastern United States. AQUATIC SCIENCES 65(4):402-414, (2003).
Abstract:	Photochemical reactions involving colored dissolved organic matter (CDOM) in natural waters are important determinants of nutrient cycling, trace gas production and control of light penetration into the water column. In this study the role of the hydroxyl radical ((OH)-O-.) in CDOM photodegradation was explored as well as the contribution of photo-Fenton chemistry to (OH)-O-. formation. Photochemically produced (OH)-O-. was observed under aerobic and dioxygen-depleted conditions in highly colored, acidic natural water samples obtained from a freshwater reach of the Satilla River, a river in the southeastern United States. Net aerobic (OH)-O-. formation along with the production of hydrogen peroxide and Fe(II) provided evidence of photo-Fenton produced (OH)-O-.. A reduction in (OH)-O-. production in the presence of iron chelators further suggests the importance of iron and the photo-Fenton reaction in this water. Apparent quantum yield values for the photochemical production of (OH)-O-. were determined from 300-320 nm. In addition, the relationship between (OH)-O-. photoproduction and effects of irradiation on the optical properties of CDOM was examined. Changes in the light absorption and fluorescence properties of water samples from the Satilla River and other natural waters were compared to (OH)-O-. production rates. The ability of constituents of Satilla River water, principally the dissolved organic matter, to scavenge (OH)-O-. was also considered. Results indicate that the photo-Fenton reaction accounts for more than 70% of total photochemical (OH)-O-. production in Satilla River water. Given the significant levels of (OH)-O-. produced in this water, it is possible that (OH)-O-. influences CDOM photobleaching.

NEWSLETTER ARTICLE	Speciation of Organics in Water	04/01/2003

Collette, T. W., T. L. Williams, AND J. C. D'Angelo. Speciation of Organics in Water. In: The Raman Review, U.S. Environmental Protection Agency, Washington, DC(1):1-3, (2003).
Abstract:	We describe herein a method for determining constants for simultaneously occurring, site-specific "microequilibria" (as with tautomers) for organics in water. The method is based in part on modeling temperature-variant Raman spectra according to the van't Hoff equation. Spectra are measured with a charge-coupled device (CCD)-based, dispersive Raman spectrometer. The success of the method depends on accurate quantification of small spectral changes that are monotonic with temperature due to changes in relative concentration of equilibrium components. The method assumes that we can neglect intensity and frequency fluctuations in spectra collected over a period of days that are not due to chemical compositional changes (e.g., frequency shifts due to ambient instrument temperature fluctuations). Also, the method assumes that we can neglect the temperature dependence of the Raman spectrum of an individual conformer. We have investigated these assumptions and found that we can typically reduce frequency and intensity fluctuations to tolerable levels by normalizing all spectra on the basis of the atmospheric N2 stretching band at 2331 cm-1, which is observed in all of our spectra. Further, we have found that we can typically neglect the temperature dependence of Raman spectra if areas of depolarized bands are used in the modeling.

PAPER IN NON-EPA PROCEEDINGS	Trace Gas Concentrations in Small Streams of the Georgia Piedmont	04/25/2003

Burke Jr., R. A. AND J. Molinero. Trace Gas Concentrations in Small Streams of the Georgia Piedmont. In Proceedings, 2003 Georgia Water Resources Conference, Athens, GA, April 23 - 24, 2003. University of Georgia, Athens, GA, 842-845, (2003).
Abstract:	Seventeen headwater watersheds within the SFBR watershed ranging from 0.5 to 3.4 km2 were selected. We have been monitoring concentrations of the trace gases nitrous oxide, methane, and carbon dioxide, and other parameters (T, conductivity, dissolved oxygen, pH, nutrients, flow rate) on an approximately monthly basis for the last year. Percentages of forested land, agricultural and pasture land, residential areas, wetlands and open water surfaces within the watershed were calculated from the National Land Cover Data (NLCD) database. Nitrous oxide concentrations have varied widely from 10 nM (atmospheric equilibrium concentration) to nearly 80 nM among the streams. Overall, the streams draining watersheds dominated by developed land use have the highest dissolved nitrous oxide concentrations although the difference is statistically significant only for comparisons with the forest and mixed land use watersheds. Also, the streams draining watershed dominated by pasture have significantly greater nitrous oxide concentrations overall than streams draining forested watersheds. These results suggest that small streams could be a significant source of nitrous oxide to the atmosphere in some watersheds. Carbon dioxide concentrations in the stream range from about 30 to 900 microM (about 3 to 75 supersaturated with respect to the atmosphere). As for nitrous oxide, the streams draining residential areas had the highest overall carbon dioxide concentrations, although the only statistically significant comparison was with streams draining forested areas. Methane concentrations range from about 0.06 to 40 microM (about 30 to 20,000 supersaturated with respect to the atmosphere). Overall, streams draining watersheds dominated by pastures had significantly higher methane concentrations than streams draining any other land use type. As for nitrous oxide and carbon dioxide, the streams from forested watersheds had the lowest methane concentrations.

PAPER IN NON-EPA PROCEEDINGS	Relations Between Land Use and Stream Nutrient Concentrations for Small Watersheds in the Georgia Piedmont	04/25/2003

Molinero, J. AND R. A. Burke Jr. Relations Between Land Use and Stream Nutrient Concentrations for Small Watersheds in the Georgia Piedmont. In Proceedings, 2003 Georgia Water Resources Conference, Athens, GA, April 23 - 24, 2003. University of Georgia, Athens, GA, 821-824, (2003).
Abstract:	We have been sampling nutrient concentrations in 17 headwater streams within the South Fork Broad River (SFBR) watershed on a monthly basis since November 2001. The streams were classified as either developed (n=4), agriculture/pasture (n=4), mixed land use (n=6) or forested (n=3) based on information from the National Land Cover Data (NLCD) database. The lowest mean nitrogen concentrations were observed in streams draining forested watersheds. A set of landscape indicators explained 93 % of the spatial variability in the total nitrogen concentrations which suggests that watershed land use has an important effect on stream nitrogen levels. Total phosphorus varied seasonally at some of the sites, with high concentrations observed during the summer and low concentrations in winter. Only 4 out of 14 non-forested sites showed higher mean total phosphorus concentrations and no relationships were found between the landscape indicators and the total phosphorus concentrations in the streams. We suggest that, in contrast to what was observed for nitrogen, in-stream sources (e. g. decaying plant material), in-stream cycling, or strong pollution sources (e. g. manure, septic tanks) are more important than watershed land use in determining the total phosphorus concentrations in these small streams.

PRESENTATION	Determining Dispersant Effectiveness Data for a Suite of Environmental Conditions	04/07/2003

Chandrasekar, S., G. A. Sorial, AND J. W. Weaver. Determining Dispersant Effectiveness Data for a Suite of Environmental Conditions. Presented at International Oil Spill Conference, Vancouver, Canada, April 7-10, 2003.
Abstract:	Chemical dispersants are used in oil spill response operations to enhance the dispersion of oil slicks at sea as small oil droplets in the water column. To assess the impacts of dispersant usage on oil spills, US EPA is developing a simulation model called the EPA Research Object-Oriented Oil Spill (ERO3S) model (http://www.epa.gov/athens/research/projects/eros/). Due to the complexity of chemical and physical interactions among spilled oils, dispersants and the sea, an empirical approach to the interaction between the dispersant and oil slick may provide a useful or practical approach for including dispersants in a model. The main objective of this research was to create a set of empirical data on three oils and two dispersants that has the potential for use as an input to the ERO3S model. These data were intended to give an indication of the amount of dispersal of these oils under certain environmental conditions. Recently, the US EPA developed an improved dispersant testing protocol, called the baffled flask test (BFT) which was a refinement of the swirling flask test. This protocol was the basis of the experiments conducted in this study. The variations in the effectiveness of dispersants caused by changes in oil composition, dispersant type, and the environmentally related variables of temperature, oil weathering, and rotational speed of the BFT were studied. The three oils that were tested were South Louisiana Crude Oil, Alaska North Slope Crude, and Number 2 fuel oil. Two dispersants that scored effectiveness above 85% by the BFT were selected for this study. A factorial experimental design was conducted for each of the three oils for the four factors, namely, volatilization, dispersant type, temperature and flask speed. Each of the four factors was studied at three levels except for the dispersant factor where only two dispersants are considered. Statistical analysis of the experimental data was performed separately for the three oils. Analysis of variance was conducted to determine which factors, or set of factors were related to the percent effectiveness. Empirical relationships between the amount of oil dispersed and the variables studied were developed.

PRESENTATION	Development of a Composition Database for Selected Multicomponent Oils	04/07/2003

Wang, Z., B. Hollebone, M. Fingas, B. Fieldhouse, L. Sigouin, M. Landriault, J. Noonan, AND J. W. Weaver. Development of a Composition Database for Selected Multicomponent Oils. Presented at International Oil Spill Conference, Vancouver, Canada, April 7-10, 2003.
Abstract:	During any oil spill incident, the properties of the spilled oil, including its chemical composition, physical properties, and changes due to weathering, are immediately important. U.S. EPA is currently developing new models for application to environmental problems associated with accidental spills and releases of petroleum hydrocarbons and other oil products. Multicomponent composition data, needed as input for simulation with the EPA Research Object-Oriented Oil Spill (ERO3S) model, is unavailable in the literature due to the complexity and expense of making the measurements. Environment Canada has previously developed a database on various physical and chemical properties of crude oils and petroleum products. In this cooperative project, 10 oils and refined products identified by the U.S. EPA are characterized by the oil spill research lab of Emergencies Science and Technology Division to extend the existing information in the database. Measured oil physical properties include API gravity, density, sulphur content, water content, flash point, pour point, viscosity, surface tension, adhesion, the equation for predicting evaporation, emulsion formation, and simulated boiling point distribution. The chemical composition of the oils include hydrocarbon groups, volatile organic compounds, n-alkane distribution, distribution of alkylated polyaromatic hydrocarbon (PAH) homologues and other EPA priority PAHs, biomarker concentrations. This project will provide the most complete and comprehensive database for the selected multicomponent oils to date. The new composition data will be integrated into the existing Environment Canada oil properties database. The results will be available to the public both on the world wide web and as a database on disc.

PRESENTATION	Should Latitudinal Atmospheric Trace Vapor Concentrations Be Reported on a Mass Density Basis?	04/23/2003

Loux, N. T. Should Latitudinal Atmospheric Trace Vapor Concentrations Be Reported on a Mass Density Basis? Presented at Georgia Water Resources Conference, Athens, GA, April 23-24, 2003.
Abstract:	For the past several decades the issue of global atmospheric trace vapor migration has been of concern to environmental professionals concerned with global distillation/cold condensation of toxic compounds, contamination of remote ecosystems, global climate change and stratospheric ozone depletion. In response to this concern, experimental databases of latitudinal trace vapor concentrations and global atmospheric transport models have been developed. These experimental databases typically contain vapor concentration data in units of mass concentration (e.g., ng/m3), volume fraction (e.g., parts per million) and mole fraction (e.g., parts per million). In contrast to measurements reported in units of volume and mole fractions, we will demonstrate that mass concentration data are functionally dependent on tropospheric temperature. Hence, the value of atmospheric trace gas concentration data reported on a mass concentration basis is severely limited unless concurrent atmospheric temperature, and perhaps even pressure and relative humidity data also are available.

PRESENTATION	Landscape-Level Indicators in Small Georgia Watersheds	04/23/2003

Senter, J., S. L. Bird, AND B. Rashleigh. Landscape-Level Indicators in Small Georgia Watersheds. Presented at Georgia Water Resources Conference, Athens, GA, April 23-24, 2003.
Abstract:	Landscape level indicators in small watersheds can be used as a screening tool to guide in-situ monitoring to confirm stream condition problems, aid listing of impaired waters under Section 303(d) of the Clean Water Act and total maximum daily load (TMDL) development, and provide reliable scientific information to energize sound local planning and land-use decisions. A series of landscape watershed indicators are developed for 12-digit HUCs in Georgia Piedmont. These landscape indicators are then compared to in-stream measures of water quality and biotic integrity at 180 different sampling sites. Indicators evaluated include impervious area, percent land cover types (forested, agricultural, developed), riparian stream cover, and point source discharges. While landscape indicators point to many in-stream quality issues, a substantial number are not indicated by these approaches.

PRESENTATION	Beyond the Indices: Relations of Habitat and Fish Characteristics in the Georgia Piedmont	04/23/2003

Rashleigh, B. AND J. G. Kennen. Beyond the Indices: Relations of Habitat and Fish Characteristics in the Georgia Piedmont. Presented at Georgia Water Resources Conference, Athens, GA, April 23-24, 2003.
Abstract:	The Georgia Department of Natural Resources has conducted biological sampling at 180 stream sites in the Georgia Piedmont (1998-99) and recorded several trophic and abundance characteristics of the fish assemblages and habitat at each site. These characteristics were combined to form an index that provides a screening tool for multiple sites across the Piedmont. In this analysis we focus at the level of the individual characteristics to gain additional insight about ecological variability and the dominant environmental gradients across sites sampled. Data were stratified to control for variation associated with basin area, which resulted in a subset of 88 sites that ranged in size from 8 to 39 km2. Principal Components Analysis (PCA) indicated that important patterns in fish data were related to the number of benthic invertivore, cyprinid, and simple lithophilic species; and pioneering vs. sunfish species. In addition, PCA indicated that habitat variability was related to riffle amount, sediment deposition and embeddedness, and bank stability, and stream width and depth. Multiple regression indicated that the number of benthic invertivore, cyprinid, and lithophilic species appeared to be primarily associated with substrate characteristics. These results can be used to guide protection and management activities in the Georgia Piedmont, and support restoration efforts of impaired streams in the state.

PRESENTATION	Photoreactivity of Chromophoric Dissolved Organic Matter (Cdom) Derived from Decomposition of Various Vascular Plant and Algal Sources	03/23/2003

Zepp, R. G., M. A. Moran, AND D. Koopmans. Photoreactivity of Chromophoric Dissolved Organic Matter (Cdom) Derived from Decomposition of Various Vascular Plant and Algal Sources. Presented at 225th American Chemical Society National Meeting, New Orleans, LA, March 23-27, 2003.
Abstract:	Chromophoric dissolved organic matter (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organic matter sources found in watersheds and coastal regions of the Southeastern United States. The species examined were derived from microbial decomposition of litter from two woody vascular plants (live oak, loblolly pine), two non-woody vascular plants (Spartina, the sea grass Thalassia) and the algal species Synechococcus. Absorption properties of the algal CDOM were significantly different that those of the CDOM derived from the terrestrial, vascular plant sources. For example, the spectral slope coefficient of the UV-visible spectra ranged from 0.028 nm(-1) for the Synechococcus CDOM to 0.010-0.015 nm(-1) for the vascular plant derived CDOM. Photoreaction of all the CDOM on exposure to simulated solar radiation resulted in increases in the spectral slope coefficients and blue shifts in their excitation-emission fluorescence spectra. The photodegradation rate constant of the Synechococcus CDOM, judged by its photobleaching at 350 nm, was almost an order of magnitude greater than that of the terrestrially derived CDOM. Exposure of CDOM from these sources produced measurable biologically labile photoproducts, even in extensively degraded material.

PRESENTATION	Photocheical Production of Hydroxyl Radical in Natural Water the Role of Iron and Dissolved Organic Matter	03/23/2003

White, E. M., P. P. Vaughan, AND R. G. Zepp. Photocheical Production of Hydroxyl Radical in Natural Water the Role of Iron and Dissolved Organic Matter. Presented at 225th American Chemical Society National Meeting, New Orleans, LA, March 23-27, 2003.
Abstract:	Photochemical hydroxyl radical (OH) production was measured in several natural waters to investigate the importance of colored dissolved organic matter (CDOM) and iron-CDOM complexes as sources of OH. High rates of OH photoproduction in highly colored, iron-rich, acidic waters are likely due to the involvement of photo-Fenton reactions, in which iron(II) and iron(II)-CDOM complexes react with hydrogen peroxide. The production of OH, hydrogen peroxide and iron(II) was monitored during the irradiation of Satilla River water, providing evidence of photo-Fenton produced OH. Addition of iron chelators, to inhibit the photoreduction of iron, reduced photochemical OH production, further indicating this pathway. The effects of OH on the optical properties of CDOM, through OH scavenging by CDOM, were also investigated for the Satilla River and other waters. Changes in the absorbance and fluorescence properties of these waters were observed in the presence of added OH sources and scavengers.

PRESENTATION	Effects of Sunlight on Carboxyl Content of Dissolved Organic Matter in the Satilla River of Georgia, United States	03/23/2003

Xie, H., O. C. Zafiriou, W. J. Cai, AND R. G. Zepp. Effects of Sunlight on Carboxyl Content of Dissolved Organic Matter in the Satilla River of Georgia, United States. Presented at 225th American Chemical Society National Meeting, New Orleans, LA, March 23-27, 2003.
Abstract:	A study examined the effect of sunlight-initiated photo-degradation of dissolved organic matter (DOM) on its carboxyl content, and the role of oxygen and iron in this process. Solar-simulated irradiations were performed on 0.2-mm filtered water samples collected from the highly colored Satilla River in Georgia, USA. Prior to the irradiations the samples were purged with air, pure oxygen or pure nitrogen to obtain three different initial oxygen levels: air-, oxygen- or nitrogen-saturated, respectively. The influence of iron was studied by comparing samples with and without addition of deferrioxamine mesylate, a strong, photochemically inert, iron-complexing ligand. The carboxyl contents of DOM before and after irradiations were determined using potentiometric titrations. Photochemically induced loss of absorbance and dissolved organic carbon (DOC), production of carbon dioxide (CO2), oxygen consumption, and variations of pH and [Fe(II)] were also monitored. For all the treatments, the carboxyl content in mmoles per liter of sample did not change significantly over the time course of irradiation up to 46 hours. However, the DOC-normalized carboxyl content (mmol/mg C) after 46 hour of exposure increased by a factor of 1.6 and 2.6 in the air- and oxygen-saturated samples, respectively. The variations of the DOC-normalized carboxyl content in all other treatments were within the experimental uncertainty. The results unequivocally indicate that the prolific photoproduction of CO2, which has long been hypothesized as a result of photodecarboxylation of DOM, cannot be accounted for by the changes of carboxyl content observed. In addition, methylation of the carboxylic groups on DOM reduced the rate of CO2 production only by 25%. This study, therefore, strongly suggests that the primary mechanism for photoproduction of CO2 was not photodecarboxylation or that carboxylic groups were photochemically regenerated.

PRESENTATION	Using Visual Plumes Predictions to Modulate Combined Sewer Overflow (Cso) Rates	10/28/2003

Frick, W. E. AND D. L. Denton. Using Visual Plumes Predictions to Modulate Combined Sewer Overflow (Cso) Rates. Presented at First Interagency Conference on Research in the Watersheds, Benson, AZ, October 28-30, 2003.
Abstract:	High concentrations of pathogens and toxic residues in creeks and rivers can pose risks to human health and ecological systems. Combined Sewer Overflows (CSOs) discharging into these watercourses often contribute significantly to elevating pollutant concentrations during wet weather, particularly following extended periods of dry weather during which pollutants accumulate, or after seasonal applications of pesticides that cause high concentrations in retention structures and flood control basins drained by the CSOs. In many instances the discharges from the CSOs are controlled by pumps that run intermittently in response to water level elevations in the retention basins. These pumps usually run at full volume, modulated only in quantum fashion when more than one pump serves the overflow structure. The either no-flow or high-flow mode of operation is insensitive to conditions in the ambient flow or the effluent, and to results that might be achieved to ameliorate the impact of pathogens or toxic residues by controlled and optimum mixing of CSO effluent and ambient streams. In principle, plume models simulating the mixing process in real time based on continuously measured stream levels and CSO volumes, together with variable flow pumps, could be used to blend the effluent with the receiving stream in a way that mitigates the impact of the CSO on the downstream environment. The Visual Plumes model is used on a CSO discharging to urban Arcade Creek in Sacramento, California to demonstrate the potential benefits that could be realized from the implementation of this kind of control strategy and technique.

PRESENTATION	Difmod2: A Next Generation Diffuse Layer Model	08/10/2003

Loux, N. T. Difmod2: A Next Generation Diffuse Layer Model. Presented at 39th International Union of Pure and Applied Chemistry Congress and 86th Conference of the Canadian Society for Chemistry, Ottawa, Canada, August 10-15, 2003.
Abstract:	Jenne (1998) suggested that the majority of uncertainty in our current ability to model the environmental partitioning behavior of ionic species on natural surfaces resulted from uncertainties in our understanding of surface acidity behavior. Traditional 2-pK Grahame-Gouy-Chapman diffuse layer models of bound surface site acidity (>SOHx(x-1)) use mass action expressions of the following form: K = [>SOH(x-1)(x-2)]aH+EXP(- delta G (excess)/RT)/[>SOHx(x-1)] where EXP() is the exponential function, delta G (excess) = F psi (F = Faraday's constant and psi = surface potential) and the other symbols have their usual meaning. Recent findings suggest that this expression for delta G(excess) may be too simplistic. DIFMOD2, a next generation diffuse layer model, relies on a redefinition of delta G(excess): delta G(excess) = delta G(electrostatic) + delta G(hydration) + delta G(dipole) + delta G (act. coeff) + delta G(charging). The first four terms to the right of the equal sign have been discussed by Loux and Anderson, 2001 (Coll. Surfs. A., 177:123-131). Delta G(charging) is described by Loux (2000; Paper 114 of Env. Comp. And Geochem. Divisions, 219th ACS National Meeting) and Loux (2002; "Effective Acidity Constant Behavior Near Zero Charge Conditions", In Keane, M (Ed.), Interfacial Applications in Environmental Engineering, 2002). Although DIFMOD2 was developed using the Entropic Balanced Surface Potential Model (Loux, 1985; PhD thesis), a version based on traditional Poisson-Boltzmann theory will be introduced and used to explain anomalous effective acidity constant behavior near the pH (ZPC).

PRESENTATION	Difmod2pb: A Next Generation Diffuse Layer Model	08/12/2003

Loux, N. T. Difmod2pb: A Next Generation Diffuse Layer Model. Presented at 39th International Union of Pure and Applied Chemistry Congress and 86th Conference of the Canadian Society for Chemistry, Ottawa, Ontario, August 10-15, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Mammalian Cell Cytotoxicity and Genotoxicity of New Drinking Water Disinfection By-Products	05/10/2003

Plewa, M. J., E. D. Wagner, A. C. Kim, R. Nelson, AND S. D. Richardson. Mammalian Cell Cytotoxicity and Genotoxicity of New Drinking Water Disinfection By-Products. Presented at 2003 Environmental Mutagen Society Conference, Miami, FL, May 10-14, 2003.
Abstract:	The disinfection of drinking water continues to protect the public health against acute disease. Drinking water disinfection by-products (DBPs) are formed by the reaction of a disinfectant with naturally occurring organic matter. Many DBPs are genotoxic and are implicated as human carcinogens and teratogens. Two new DBPs, 2,3,5-tribromopyrrole (TBP) and iodoacetic acid (IA) were isolated and chemically characterized. TBP was isolated from chlorine dioxide-chlorine and chlorine dioxide-chloramine treated water from the Sea of Galilee, Israel, that contained bromide levels of approximately 2 mg/L. This is the first time a halopyrrole has been identified as a DBP. Using a microplate-based chronic cytotoxicity assay, TBP was a strong cytotoxin in Chinese hamster ovary (CHO) cells. The concentration of TBP that reduced the CHO cell density by 50% (%C?) after 72 h exposure was 60.6 microM. At concentrations above 150 microM, TBP induced genomic DNA damage in CHO cells treated for 4 h using the single cell gel electrophoresis (SCGE comet) assay. IA was identified in chloramine-treated drinking water from Texas, U.S.A. that contained bromide levels of 0.25 mg/L. IA is a very potent CHO cell chronic cytotoxin with a %C? value of 2.9 microM. IA is also the strongest genotoxic agent of the 22 DBPs we have analyzed. IA at concentrations of 5 microM and above after 4 h exposure induced genomic DNA damage in CHO cells. For the monohalogenated acetic acids the rank order, from high to low toxicity, for both CHO cell chronic cytotoxicity and acute genotoxicity was iodoacetic acid > bromoacetic acid >> chloroacetic acid.

PRESENTATION	Diverse Models for Solving Contrasting Outfall Problems	01/30/2003

Frick, W. E. Diverse Models for Solving Contrasting Outfall Problems. Presented at 4th International Exhibition and Conference on Environmental Technology, Athens, Greece, January 30-February 4, 2003.
Abstract:	Mixing zone initial dilution and far-field models are useful for assuring that water quality criteria will be met when specific outfall discharge criteria are applied. Presented here is a selective review of mixing zone initial dilution models and relatively simple far-field transport models. An argument is made for the continued diversity of model development, based on the complexity of the problems addressed, theoretical and experimental uncertainty, model accessibility, and the long-term outlook for improvement.

PRESENTATION	Estimation of Physiochemical Properties of Organic Compounds By Sparc	03/23/2003

Hilal, S. H., L. A. Carreira, AND S. W. Karickhoff. Estimation of Physiochemical Properties of Organic Compounds By Sparc. Presented at 225th American Chemical Society National Meeting, New Orleans, LA, March 23-27, 2003.
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 8000 physical property data points on properties such as vapor pressure, boiling point, solubility, Henry's constant, GC retention times, Kow, etc. At the present time, SPARC predicts ionization pKa, carboxylic acid ester hydrolysis rate constant, E1/2 reduction potential in many solvents, gas phase electron affinity and numerous physical properties for a broad range of molecular structures.

PRESENTATION	Modeling Dispersant Interactions With Oil Spills	03/23/2003

Weaver, J. W. AND M. C. Boufadel. Modeling Dispersant Interactions With Oil Spills. Presented at 225th American Chemical Society National Meeting, New Orleans, LA, March 23-27, 2003.
Abstract:	EPA is developing a model called the EPA Research Object-Oriented Oil Spill Model (ERO3S) and associated databases to simulate the impacts of dispersants on oil slicks. Because there are features of oil slicks that align naturally with major concepts of object-oriented programming, this approach was chosen to implement the model. The two most obvious of these are the splitting of slicks into patches and the dispersal of oil into droplets. These have aspects of inheritance and polymorphism as individual slicks and droplets share some common behaviors (polymorphism) and share composition at the time of separation (inheritance). Other aspects of the object-oriented approach give the ability of the model to specify components of the graphical user interface and solution technique. This allows the computer code to contain models based upon varying conceptualization and/or suites of test problems. Each of these can have its own interface and selection of numerical solver that are generated automatically. When selected, each model can "tell" the interface what inputs are needed from the user, what numerical technique to use, and what outputs to display. The main model within ERO3S treats spreading of oil as a function of density, viscosity, interfacial tension, wind and current speeds. By imposing the implicit function theorem on the spreading equation, each of these parameters of the oil slick can vary with time. Thus change in physical properties driven by compositional change can be incorporated into the model. Compositional change is driven by primarily volatilization, but also dissolution. The data that drives the simulations is taken from four sources: chemical properties from the EPA/University of Georgia chemical property estimator called SPARC (SPARC--Performs Automated Reasoning in Chemistry), historical climate data from NOAA buoy data, a database of oil compositions and physical properties developed by Environment Canada, and a set of data on the effects of dispersants on oil slicks developed at the University of Cincinnati. The dispersant data were measured using a newly developed dispersant effectiveness testing protocol. This empirical data set includes the effects of oil composition, dispersant type, weathering, wave energy, temperature, and salinity. These properties are then matched to simulated conditions within the model. Temperature variation, for example, is treated by choosing a sequence of diurnal variations in temperature from the buoy database, generating temperature-dependent Henry's constants and solubilities from SPARC, and using the empirical dispersant data set to approximate dispersal of the oil slick. Given the time since spilling the oil, the simulated amount of weathering and the salinity, the transfer of oil into the water column due the dispersal of the oil is determined by the model. Simulation results with site-specific data from a tidal marsh in New York are presented as illustrative of planning exercises on dispersant usage.

PRESENTATION	Predicting Environmental Concentrations of Airborne Pollutants in Terrestrial Receptors: the Case of Mercury	09/08/2003

Ambrose Jr., R. B., I. X. Tsiros, AND T. A. Wool. Predicting Environmental Concentrations of Airborne Pollutants in Terrestrial Receptors: the Case of Mercury. Presented at 8th International Conference on Environmental Science and Technology, Lemnos, Greece, September 8-10, 2003.
Abstract:	The question of mercury in the environment has rapidly become one of the high-profile environmental issues in several countries and internationally. There are environmental and human health concerns associated with elevated levels of mercury linked to industrial mercury emissions. Natural and anthropogenic emissions to the atmosphere can subsequently be released by deposition to terrestrial receptor sites such as watershed soils and surface waters. Recent studies have demonstrated that airborne mercury is the dominant source of mercury to watersheds in many areas, and that similar atmospheric mercury inputs will result in different mecury levels in fish as the result of differences in chemistry and dynamics of the water body, the hydrologic response of the watershed, and the form of mercury deposited to the watershed. Therefore, agencies involved in the regulation of mercury and the development of mercury policy need data and tools that will assist them in assessing and managing mercury risks and to support programs aimed at reducing mercury loading. For example, the US EPA's total maximum daily load (TMDL) program is used to set the maximum load of pollutants that can be discharged within a given impaired water of a catchment that receives pollutant contributions from both air and water or just air. Determination of TMDLs for mercury in watersheds must therefore include point source discharges to the water as well as atmospheric deposition resulting from nearby and distant atmospheric emissions and natural background sources. Atmoshperic deposition can occur directly onto the aquatic systems as well as to the watershed, where it may accumulate in the soils, with a fraction ultimately delivered to the surface water network. The TMDL must quantify the contributions of Hg to the terrestrial and aquatic systems in a catchment from local, regional and global sources. To address this need, a platform for atmospheric mercury deposition monitoring and source attribution is required along with a combination of transport/fate model development and process studies. This paper presents a modeling analysis of airborne mercury fate in catchments which are important receptors in terms of exposure to mercury. The analysis is performed by coupling components of simulation models developed and published previously by the authors. Results from comparison of observational and simulated data for individual river catchments in the context of TMDLs in Georgia, USA are presented. The results obtained offer some degree of confidence in the model's ability to relate readily available environmental parameters to mercury fluxes in catchments. In addition, since loading of mercury deposited from the atmosphere onto the catchment soils is of major importance, a sensitivity analysis is performed to evaluate parameters controlling the predicted mercury loading flux, including intra- and inter-annual weather variability, landscape characteristics and other environmental parameters. Scenarios representing soils with different landscape and hydrologic transport characteristics were developed and simulations were designed to calculate mercury flux response to microclimatic and other environmental variables for several mercury concentration level scenarios. The predictions presented in this work can be useful tools since they might allow air pollution control officials to better evaluate the fate of airborne mercury deposited onto terrestrial receptor sites when considering technological approaches to managing and reducing mercury releases in the environment. 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 watersheds. Such linked modeling systems will be critical for assessing multiple interactive stressors and for evaluating the effectiveness of criterion-based restoration goals.

PRESENTATION	Dissolved Organic Carbon (Doc) Concentrations in Small Streams of the Georgia Piedmont	05/27/2003

Molinero, J. AND R. A. Burke Jr. Dissolved Organic Carbon (Doc) Concentrations in Small Streams of the Georgia Piedmont. Presented at North American Benthological Society Annual Meeting, Athens, GA, May 27-31, 2003.
Abstract:	Dissolved organic matter (DOM) supports microbial activity and contributes to transport of N and P in streams. We have studied the impact of land uses on dissolved organic carbon (DOC) concentrations in 17 Georgia Piedmont headwater streams since January 2001. We classified the watersheds as developed (n =4), pasture/agricultural (n=4), forested (n=3) and mixed land uses (n=6). Mean DOC concentrations were low (0.95-1.28 mg C/l) in forest streams and somewhat higher in other watersheds. However, no significant correlations were found between stream DOC and watershed land use, and neither population density, road density nor discharge explained a significant portion of DOC variability. A significant inverse correlation was found between DOC and oxygen concentrations (R2 = 0.70). DON was a variable portion (5 to 46 %) of the total dissolved nitrogen in the streams. We conclude that (1) conversion of forest to other land uses increases DOC in Georgia Piedmont streams, that (2) DOM influences dissolved oxygen concentrations and (3) plays a significant role in the transport of nitrogen in these streams, but (4) land use and several common landscape indicators are poor predictors of DOC concentrations.

PRESENTATION	Using Canines in Source Detection of Indoor Air Pollutants	07/21/2003

Bird, S. L. Using Canines in Source Detection of Indoor Air Pollutants. Presented at Indoor Air Quality Problems and Engineering Solutions Symposium, Research Triangle Park, NC, July 21-23, 2003.
Abstract:	Dogs have been used extensively in law enforcement and military applications to detect narcotics and explosives for over thirty years. Dogs are regularly used in arson investigations to detect accelerants since they are much more accurate at discriminating between accelerants and by-products of combustion than field VOC detectors. Controlled laboratory studies have documented accurate detection by dogs of specific compounds associated with explosives and narcotics at air concentrations below 1 ppb. Relatively few applications have taken advantage of this canine capability in the environmental arena. Dogs could be used to rapidly screen houses for problems such as vapor intrusion of a variety of VOCs, identifying the presence of mildews and toxic molds, or rapidly identifying houses where illicit pesticide use has occurred. Dogs can serve as a rapid screen to indicate the presence of a substance in air in a house and are also capable of moving towards the source of volatile materials. Benzene, toluene, ethylene, and xylene (BTEX) are major constituents of gasoline and frequent culprits in vapor intrusion into buildings from contaminated groundwater. Since indoor air contamination can also occur from household sources responsibility is often contested. This presentation demonstrates the use of dogs to signal the presence of the BTEX suite of compounds and the ability of the canines to move to the source of contamination.

PRESENTATION	Modeling the Response of Fish Populations to Eutrophication	08/03/2003

Rashleigh, B. AND D. J. Randall. Modeling the Response of Fish Populations to Eutrophication. Presented at Ecological Society of America Annual Meeting, Savannah, GA, August 3-8, 2003.
Abstract:	Eutrophication resulting from nonpoint source pollution is one of the largest environmental problems in lakes and reservoirs around the world. Two characteristics of eutrophication, decreased dissolved oxygen and increased concentration of ammonia, are known to affect fishes, yet models of eutrophication rarely include fishes. We developed a model to quantify population-level effects of eutrophication on fish. The model uses oxygen, ammonia, pH, and temperature outputs from a water quality model as driving variables and incorporates results from individual-level fish toxicology studies of growth, survival, and reproduction conducted in the laboratory. The model is applied to Lake Peipsi in Estonia/Russia. We focus on two common, commercially-important fish species, smelt (prey) and pikeperch (predator). Results indicate that the two fish species respond similarly to eutrophication, the fish populations are most sensitive to changes in oxygen, and over time, ammonia and oxygen changes are synergistic in their effects on populations. This model can be used to assess the response of the fisheries to future water quality scenarios and restoration activities.

PRESENTATION	Modeling the Effects of Eutrophication of Fish Populations	08/04/2003

Rashleigh, B. AND D. J. Randall. Modeling the Effects of Eutrophication of Fish Populations. Presented at Ecological Society of America Annual Meeting, Savannah, GA, August 3-8, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Effects of Fertilizer Type (Chicken Litter Vs. Inorganic Fertilizer) and Cattle Grazing on the Soil Microbial Community	03/25/2003

Kisselle, K., R. G. Zepp, M. Molina, R. A. Burke Jr., AND A. J. Franzluebbers. Effects of Fertilizer Type (Chicken Litter Vs. Inorganic Fertilizer) and Cattle Grazing on the Soil Microbial Community. Presented at 2003 Annual Symposium: Soil Biodiversity and Function, Lancaster, United Kingdom, March 25-27, 2003.
Abstract:	Pasture plots included unharvested, hayed, light and heavy cattle grazing pressure, fertilized with either inorganic N-P-K or broiler litter. Total phospholipid fatty acids (PLFAs) followed a seasonal trend and were higher in grazed plots than hayed & unharvested plots. Fungi and protozoa made up a larger percentage of the microbial community during the growing season, while bacteria and actinomycetes made up more in the autumn samples. Broiler litter plots had less fungi and slightly more bacteria and actinomycetes than plots receiving inorganic fertilizer. The hayed treatment had higher quantities of protozoan PLFAs and smaller quantities of bacterial PLFAs. Indirect evidence of top-down control of bacterial populations in all plots is given by a significant inverse relationship between a protozoan PLFA and the sum of several bacterial PLFAs.

PRESENTATION	Gc/MS Identification of Drinking Water Disinfection By-Products from Milwaukee's New Ozonation Plants	06/08/2003

Thruston Jr., A. D., S. D. Richardson, L. A. Couillard, C. Lewis, AND P. Klappa. Gc/MS Identification of Drinking Water Disinfection By-Products from Milwaukee's New Ozonation Plants. Presented at 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 8-12, 2003.
Abstract:	The Milwaukee Water Works recently added ozonation disinfection facilities to their municipal drinking water treatment. Coupling ozone treatment with biologically active filtration (BAF) was seen as a logical step to enhance multiple water quality objectives (an effective barrier to further Cryptosporidium contamination in light of the 1993 outbreak, in which 400,000 people became ill, and 100 people died), and fit current industry and regulatory trends toward organics removal. Because of concerns about potential increased levels of disinfection by-products (DBPs) in the finished water resulting from ozonation, special emphasis was placed on the use of biological filtration as a technique to potentially remove most of these DBPs from the finished water - which is of growing interest in the U.S. This led to a collaboration with EPA's National Exposure Research Laboratory (NERL) facility in Athens, GA to collect a series of samples from various stages of water treatment from the Milwaukee plant in August 2002. These samples were analyzed for a comprehensive list of DBPs (including many DBPs that are not regulated).

PRESENTATION	Disinfection By-Products of Health Concern in Drinking Water: Results of a Nationwide Occurrence Study	06/08/2003

Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, H. S. Weinberg, R. Chinn, M. J. Sclimenti, S. Pastor, AND G. D. Onstad. Disinfection By-Products of Health Concern in Drinking Water: Results of a Nationwide Occurrence Study. Presented at 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 8-12, 2003.
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. Environmental Protection Agency (EPA) has regulated several DBPs; however, most DBPs have not been tested for adverse health effects due to the high costs involved. In order to prioritize new DBPs for health effects testing, we initiated a Nationwide Occurrence Study to quantify 'high priority' DBPs (those predicted by toxicology experts to possibly have an adverse health effect) to determine how often they occur and at what levels. The fate and transport of these DBPs in the distribution system was also studied, and new DBPs were identified.

PRESENTATION	EPA's on-Line Calculators and Training Course	03/12/2003

Weaver, J. W. EPA's on-Line Calculators and Training Course. Presented at U.S. EPA Office of Underground Storage Tanks Annual Conference, San Francisco, CA, March 10-12, 2003.
Abstract:	EPA has developed a suite of on-line calculators called "OnSite" for assessing transport of environmental contaminants int the subsurface. The calculators are available on the Internet at http://www.epa.gov/athens/onsite, and are divided into four categories: Parameter Estimates, Simple Transport Models, Unit Conversions, and Scientific Demos Since their inception in 1998, the calculators have been used by State Agencies, EPA Regional Offices and private consulting firms; and there has been a steady increase in their use. The web site will be demo-ed with emphasis on the latest additions, which include estimation of biodegradation rates from field data, uncertainty in model results and State-specific chemical data for use as inputs.With tight budgets, employee turnover and high workloads, there may be little time and money for training. EPA is adapting its modeling training course "Modeling Subsurface Transport of Petroleum Hydrocarbons" for the Internet. The course is divided into self-study modules, each with a set of objectives, 15 to 20 web pages that are enhanced with graphics and on-line calculators, review, a quiz. A certificate is automatically generated when the quiz is passed. Currently completed modules focus on fate and transport of contaminants, with more to be added in the coming months.

PRESENTATION	Software Tools for Assessment of Contaminated Sites	03/12/2003

Weaver, J. W. Software Tools for Assessment of Contaminated Sites. Presented at U.S. EPA Office of Underground Storage Tanks Annual Conference, San Francisco, CA, March 10-12, 2003.
Abstract:	Models have become an integral part of decision-making for many LUST sites if only because they form the basis of RCBA tiered assessments. Models, though, are based on a series of assumptions concerning how chemicals behave in the environment, how water flows through the ground, even how a contaminant release occurs. How can you identify these assumptions? We'll present a field guide to models that helps identify model assumptions and their impacts on model results. Data is important too and we'll show how the amount and quality of available data affect model results. In practice, inputs to models are selected from various sources, including measurements, literature, defaults, estimates, and calibration. A number of these issues are addressed by a set of on-line calculators that EPA developed for assessment of contaminated sites. We'll look at calculators that can be used to estimate parameters, convert units, assess uncertainties in calculations. Participants that bring laptops can run the calculators themselves from a CD that will be provided. Lastly we'll look at ways to evaluate modeling work. Some steps of evaluation of models can be boiled down to nearly a recipe; also needed are knowledge of fate and transport, modeling in general, and the specific details of the model used.

PRESENTATION	Risk Assessment Analyses Using EPA's on-Line Site-Specific Transport Models and Field Data	08/12/2003

Weaver, J. W. Risk Assessment Analyses Using EPA's on-Line Site-Specific Transport Models and Field Data. Presented at 2003 Resource Conservation and Recovery Act National Meeting: Putting Resource Conservation into Resource Conservation and Recovery Act, Washington, DC, August 12-15, 2003.
Abstract:	EPA has developed a suite of on-line calculators and transport models to aid in risk assessment for subsurface contamination. The calculators (www.epa.gov/athens/onsite) provide several levels of tools and data. These include tools for generating commonly-used model input parameters, transport models, unit conversions and scientific demos. Background information is provided on the calculators, along with an on-line training course on contaminant fate, transport and modeling. The purpose of these resources is to simplify and promote the correct use of the underlying ideas. An example of an input parameter calculator is the retardation factor used in subsurface transport models. The web site includes chemical data sets from superfund, regional RCRA programs and State Agencies. Thus access is provided to a suite of data sets in addition to implementing the formula itself. The available models address recharge-driven plume diving of contaminant plumes; risk estimates of contaminants at receptor locations; and the range of uncertainty in model outputs. Visitors to the web site have used these to design monitoring networks and assess the quality of modeling reports submitted in support of natural attenuation remedies. The presentation will be based on an example application of the web calculators that was drawn from a State Agency case file, and includes evaluation of field data, model application and parameter uncertainty. Suggestions for additions to the calculator site are welcome as we wish to expand the applicability of the web site by addressing more classes of problems.

PRESENTATION	Modeling of Metal Binding on Humic Substances Using the Nist Database: An a Priori Functional Group Approach	05/12/2003

Zhang, Z. Z. AND G. W. Bailey. Modeling of Metal Binding on Humic Substances Using the Nist Database: An a Priori Functional Group Approach. Presented at Seventh International Symposium on Fish Physiology, Toxicology, and Water Quality, Tallinn, Estonia, May 12-15, 2003.
Abstract:	Various modeling approaches have been developed for metal binding on humic substances. However, most of these models are still curve-fitting exercises-- the resulting set of parameters such as affinity constants (or the distribution of them) is found to depend on pH, ionic strength, and concentrations of metals and humic substances. Consequently, these models are not satisfactory to predict metal binding under environmental settings. We have developed an a priori model based on the elemental composition and functional group concentrations of humic substances, using the National Institute of Standard and Technology (NIST) database of critically selected stability constants of metal complexes. We tabulated the stability constants of metal complexes with selected functional groups and have plotted the corresponding conditional stability constants at several pH levels. These data showed that in addition to oxygen-bearing groups, the nitrogen-bearing groups and sulfur-bearing groups are also important for metal binding. The amino acid group plays a significant role for binding of Cu(II), Hg(II), Cr(III) and Fe(III), whereas the SH-functional group is important for the binding of soft Lewis acids' metals, such as Cd(II), Hg(II), and Pb(II). We have shown that such a simple model is capable of predicting adsorption and competitive adsorption of metals when the concentration of metals is below 10(-5) to 10(-6) M, which is the relevant metal concentration under most environmental settings.

PRESENTATION	Modeling Chemical Fate and Metabolism for Computational Toxicology	05/05/2003

Weber, E. J., T. W. Collette, W. J. Jones, J. F. Kenneke, C. S. Mazur, L. A. Suarez, C. T. Stevens, J. W. Washington, K. Wolfe, N. L. Wolfe, G. W. Bailey, AND R. S. Parmar. Modeling Chemical Fate and Metabolism for Computational Toxicology. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	The goal of ORD's Computational Toxicology initiative is to develop the science for EPA to prioritize toxicity-testing requirements for chemicals subject to regulation. Many toxic effects, however, result from metabolism of parent chemicals to form metabolites that are much more toxic than the parent. Consequently, an accurate computerized simulator of metabolism is essential for meeting the objectives of the Computational Toxicology initiative. Because the liver is the primary organ for chemical metabolism, initial efforts will focus on the development of a metabolic simulator describing liver metabolism (i.e., a virtual liver). The primary goal of this research is to develop a computational system that will predict and prioritize metabolic pathways for the liver metabolism of organic chemicals.The metabolic simulator must allow for prioritization of many competing metabolic pathways for parent chemicals. The prioritization process requires the integration of reliable rate data. When this data is absent, it is necessary to populate a database with metabolic rate constants based on: 1) experimentally measured values, 2) rate constants derived from mechanistic-based SPARC or QSAR models, and 3) advanced spectroscopic techniques (e.g., NMR) for measuring metabolic rate constants and identifying metabolites in vivo and in vitro. An initial challenge of this research is the selection of representative chemicals for study. To ensure focus on the highest priority chemicals, a workgroup specifically on metabolism will be formed. Such a workgroup will allow partners outside of ORD (e.g., OPPT, OSW and OW) an opportunity to have their priority questions answered in addition to the ORD research agenda.

PRESENTATION	Three-Dimensional Modeling of Cohesive Sediment Transport in a Partially Stratified Micro-Tidal Estuary to Assess Effectiveness of Sediment Traps	10/01/2003

Hayter, E. J., V. Paramygin, AND C. John. Three-Dimensional Modeling of Cohesive Sediment Transport in a Partially Stratified Micro-Tidal Estuary to Assess Effectiveness of Sediment Traps. Presented at 7th International Conference on Nearshore and Estuarine Cohesive Sediment Transport Processes, Williamsburg, VA, October 1-4, 2003.
Abstract:	The three-dimensional (3D) finite difference model Environmental Fluid Dynamics Code (EFDC) was used to simulate the hydrodynamics and sediment transport in a partially stratified micro-tidal estuary. The estuary modeled consisted of a 16-km reach of the St. Johns River, Florida, and two tributaries - the Ortega and Cedar Rivers. The Cedar River flows into the Ortega a few kilometers from the confluence of the Ortega and St. Johns Rivers. The objective of this study was to investigate the effect of sediment traps (with varying sediment removal efficiencies) placed along the Cedar River on the net sediment flux from the Cedar River. Sediment traps have been proposed as a remedial measure to minimize the transport of contaminated sediments from the Cedar River into the Ortega and St. Johns Rivers. In addition to the Cedar and Ortega Rivers, there are three secondary tributaries of the system - Fishing Creek, Butcher Pen Creek and Williamson Creek. At the mouth of the Ortega River, the semi-diurnal tidal range varies from 0.14m (neap tide) to 0.28m (spring tide), with a mean of 0.19m. The bottom and suspended sediments are mostly mixture of clays, silts and organic matter. Suspended sediment concentrations are normally in the 10 - 20 mg/L range. However, during runoff events it usually exceeds 100 mg/l. The dominant range of organic content in the bottom sediment is 20-30%.An orthogonal-curvilinear grid was developed to represent the modeling domain. The model consisted of 2,856 active cells. Six vertical layers were used. Measured water surface elevations and salinities at three levels over the water column were used at the open water boundaries in the St Johns River. In the six tributaries, the required discharge time-series were obtained from a watershed model (SWMM). The boundary values for suspended sediment concentrations were obtained using a sediment concentration-discharge-rating curve. The model was cold-started for a 30-day spin-up period. The resulting restart file was used to hot-start the runs made during the subsequent 121-day calibration period and 180-day confirmation period. Satisfactory agreements were obtained between measured and predicted water surface elevations, current velocities, and sediment fluxes (at three transects during the calibration period) during both the calibration and confirmation periods.

PRESENTATION	Predicting Bacterial Concentration on the Nation's Beaches	05/05/2003

Frick, W. E. Predicting Bacterial Concentration on the Nation's Beaches. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	A classical example of the failure of institutions and environmental technology to protect the nation's aesthetic, recreational, and public health values is represented by the July-August, 1999 Huntington Beach, California beach closure. This multi-million dollar regional public health disaster (high bacterial concentrations) affected perhaps a million vacationers and may be compared with major environmental disasters, such as the Exxon Valdez oil spill, in shaping public perceptions. The short-term result was the abandonment, under intense political pressure, of the local sanitation district's 301(h) waiver of secondary treatment privileges. As an important discharger in the area, it has committed to upgrade to full secondary treatment and to chlorine disinfection of the effluent discharged more than four miles offshore, at a capital improvement cost estimated to range from $250M to $400M.However, an independent science review of extensive monitoring data has yet find a strong link between offshore plume concentrations and distribution and surf zone elevated bacterial levels, the two regions being separated by bands of much lower concentrations. There are indications that other sources ? a power plant's effluent also serving combined sewer overflows, the Santa Ana River, a bird sanctuary, public toilets, and unidentified renegade sources ? may be important determinants of surf zone pollution. Meanwhile, bacterial sampling typically requires 48-hour incubation times, severely decreasing the ability of bacterial monitoring programs to both protect public health and optimize public access to beaches. This project envisions the formulation of a model, working title Visual Beach, to be based on the EPA Visual Plumes program and other models and water circulation estimation techniques. In collaboration with the Orange County Sanitation District, it will be tested against routine monitoring conducted by the District. If successful, the model may help develop effluent disinfection that will prevent high waste-field concentration when shoreward movement is forecasted. Secondly, the model may help identify other potential sources contributing to the high bacterial levels, leading to their remediation. The ultimate product will utilize telemetered real-time monitoring data and fluid dynamical models and prognostic products to predict surf zone bacterial concentrations with enough lead time to allow for adequate disinfection of the district's effluent, identification of contributing sources, and health advisory lead times.

PRESENTATION	Emerging Disinfection By-Products of Toxicological Interest: Results of a Nationwide Occurrence Study	05/05/2003

Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, H. S. Weinberg, R. Chinn, M. J. Sclimenti, S. J. Pastor, AND G. D. Onstad. Emerging Disinfection By-Products of Toxicological Interest: Results of a Nationwide Occurrence Study. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	The Safe Drinking Water Act and Amendments requires that EPA address disinfection by-products (DBPs) in drinking water. DBPs are formed when a disinfectant (such as chlorine) reacts with organic matter and/or bromide naturally present in source waters. Drinking water disinfection by-products (DBPs) are of concern because epidemiologic studies indicate that some may be responsible for cancer and reproductive/developmental effects in human populations, and other studies have shown that certain DBPs cause cancer in laboratory animals. A few DBPs are regulated; however, most DBPs have not been tested for adverse health effects due to high costs involved. In order to prioritize new DBPs for health effects testing, we initiated a Nationwide Occurrence Study to quantify ?high priority' DBPs (those predicted by experts to potentially cause an adverse health effect at relatively low doses) to determine how often they occur and at what levels. The fate and transport of these DBPs in the distribution system was also studied, and new DBPs were identified. Scientists from the University of North Carolina and the Metropolitan Water District of Southern California collaborated with NERL scientists on this effort. Drinking waters were chosen across the United States in locations to provide waters with low and high bromide, different pH conditions, and different organic matter levels. Regulated and Information Collection Rule DBPs were also measured for comparison purposes. Analytical methods were developed for quantifying the high priority DBPs in drinking water, and mass spectrometry methods were used to identify new DBPs. Most of the high priority DBPs were found in drinking waters across the U.S.. High priority DBPs identified and quantifiedinclude 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), brominated forms of MX, iodo-trihalomethanes, halomethanes, halonitromethanes, haloacids, haloacetonitriles, haloketones, haloacetates, haloamides, and a few non-halogenated DBPs. Significant results include finding MX at much higher levels than previously believed possible (300-400 ng/L), finding the highest levels of iodo-THMs at a plant using chloramines for disinfection, and finding the highest levels of dihaloaldehydes at a plant using ozonation. In addition, iodo-acids were identified for the first time as DBPs, as well as several new brominated haloacids. Brominated DBPs are important, as toxicology studies suggest that certain brominated DBPs may be of higher health concern than the chlorinated species. This research expands our knowledge on the occurrence of DBPs beyond those that are currently regulated, will help to prioritize future DBP health effects research, and will allow EPA's Office of Water to make improved decisions regarding the safety of drinking water and to ultimately minimize any that are found to be hazardous.

PRESENTATION	Preventing Contamination of Public Water Supply Wells Using Computerized Modeling and Mapping Tools	05/05/2003

Kraemer, S. R. Preventing Contamination of Public Water Supply Wells Using Computerized Modeling and Mapping Tools. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	The EPA Office of Research and Development and the Office of Ground Water and Drinking Water have collaborated since 1998 on the development of a public domain ground-water flow modeling system designed to facilitate capture zone delineation and protection area mapping for public water supply wells in the United States. This activity is authorized by the Safe Drinking Water Act, and implemented through the state and tribe Wellhead Protection Programs (WHPP) and Source Water Assessment Planning (SWAP). The 32-bit windows software, called WhAEM2000, provides an interactive computer environment for the delineation of protection areas based on radius methods, well in uniform-flow solutions, and geohydrologic modeling methods. Protection areas are designed with and overlaid upon US Geological Survey Digital Line Graph (DLG) or other electronic base maps. Base maps for the country and the WhAEM2000 software are available for download from the EPA Center for Exposure Assessment Modeling web site. Geohydrologic modeling for steady pumping wells, including the influence of hydrological boundaries, such as rivers, recharge, no-flow boundaries, and inhomogeneity zones, is accomplished using the state-of-the-art numerical modeling technique known as the analytic element method. Reverse gradient tracelines of known residence time emanating from the pumping center are used to delineate the capture zones. WhAEM2000 has on-line help and tutorials, and good modeling practice documentation. A "Working with WhAEM2000" case study is available for the wellfield of Vincennes, Indiana, which is located in the glacial outwash of the Wabash River. The software development team includes Haitjema Consulting, LLC (Bloomington, IN), Computer Sciences Corp (Athens), and WHPA Inc (Bloomington, IN). It is anticipated that managing the potential for leaks and spills of contaminants in the properly delineated source water protection zone will result in better water quality at the faucet for millions of Americans.

PRESENTATION	Nutrients in Watersheds: Developing Enhanced Modeling Tools	05/05/2003

Washington, J. W. Nutrients in Watersheds: Developing Enhanced Modeling Tools. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Nutrient enrichment is one of the most important stressors causing water-resource impairment. These impairments are causing devastating changes: 1) high nitrate concentrations have rendered the groundwaters and reservoirs in many regions impotable -- especially in the rural areas of the US heartland where these sources are important domestic-water sources; 2) eutrophic effects in many fresh surface waters are stimulating harmful species -- e.g., the zebra mussel in the Great Lakes and pfiesteria in the Neuse River; and 3) the commercial productivity of our nation's coastal waters is in the midst of protracted decline, e.g. hypoxia and "dead zones" in estuaries of the Gulf of Mexico. Because of these and other effects, unchecked nutrient fluxes in the environment constitute one of the gravest impacts on the quality of life in the US. This project is divided into two major areas: 1) Process Science; and 2) Model Development. The Process Science research aims to identify and better elucidate specific sources of uncertainty with respect to nutrient fate in the environment. In the Modeling Development research area, several models are being developed in parallel. We plan to use some of these models to illuminate relations among media that we intend to quantify as we understand them better, e.g., effect of groundwater nutrients on surface-water quality. We plan to link other models in an open architecture environment that will be available to Program-Office users, e.g., Sediment Diagenesis and WASP. This improved suite of models is being developed in partnerships with Region 4, Office of Water (OW) National Nutrient Criteria Program (NNCP), USDA/ARS; and USGS.

PRESENTATION	Pc-Based Supercomputing for Uncertainty and Sensitivity Analysis of Models	05/05/2003

Babendreier, J. E., R. S. Parmar, K. Wolfe, S. Uter, AND M. McKendrick. Pc-Based Supercomputing for Uncertainty and Sensitivity Analysis of Models. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Evaluating uncertainty and sensitivity of multimedia environmental models that integrate assessments of air, soil, sediments, groundwater, and surface water is a difficult task. It can be an enormous undertaking even for simple, single-medium models (i.e. groundwater only) described by only a handful of variables and a unique set of site-specific data. The challenge then of examining ever more complex multimedia models, with 100's to 1000's of variables, is a formidable one. Today, quantitative assessment of integrated multimedia models that simulate hundreds of sites, spanning multiple geographical and ecological regions is becoming a standard risk assessment question for national policy development.A characteristic of uncertainty and sensitivity analyses for very high order models (VHOMs - indicating large numbers of variables) is their need for significant levels of computational capacity to perform large numbers of individual model simulations. While this aspect is emerging as a critical area for environmental model evaluation, resources for Windows-based, PC-based modeling have been limited by an associated lack of supercomputing capacity. Supercomputing achieved through use of personal computer (PC) clusters has expanded rapidly in recent years. Less common though are clusters that support Windows-based approaches. To facilitate model evaluation tasks for EPA's modeling systems, NERL-Athens has developed a Windows-based 270+ GHz PC-based Supercomputer for Model Uncertainty and Sensitivity Evaluation (SuperMUSE). Design and construction of SuperMUSE is described here. Extendable to many of EPA's computer models, conceptual layout of an accompanying platform-independent, Java-based parallel processing software tool set is also discussed. Together, the hardware and software tool set concept represents a key component of future modeling frameworks that the Agency is moving towards, and will ultimately strengthen our ability to validate regulatory-based modeling efforts. Advantages of the technology developed include: 1) the approach is scalable to individual user (or program office) needs (i.e. clustering from 2 to 2000 PCs), 2) it can be applied to any Windows-based modeling system (and also works for Linux systems), 3) its targeted to deliver a specific capability (i.e. uncertainty and sensitivity analyses), 4) it's a local solution, delivering to researchers and clients autonomy from large supercomputing centers formally providing these services, and 5) it's cheap and can be constructed and operated by relative novices with limited knowledge of computer science. Relating this to how we meet client needs, examples of national-scale and site-scale multimedia application are presented for key environmental exposure and risk assessment problems.

PRESENTATION	Mercury Contamination of Subsistence Fisheries on Tribal Lands: A Partnership of Ord, Region 8 and Cheyenne River Sioux Reservation	05/05/2003

Johnston, J. M., D. Hoff, R. Hoogerheide, R. Edgar, D. Wall, AND C. Ducheneaux. Mercury Contamination of Subsistence Fisheries on Tribal Lands: A Partnership of Ord, Region 8 and Cheyenne River Sioux Reservation. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	In a prior collaborative 3 year study with the Cheyenne River Sioux Tribe Department of Environmental Protection (CRST DEP), and the Agencies' Environmental Response Team, RegionVIII investigated Hg levels in fish tissues from the Cheyenne River and Lake Oahe in South Dakota. In 2000, the CRST released a fish advisory recommending less consumption of fish, especially for sensitive individuals within their population (pregnant and elderly). One mitigating risk management recommendation from the CRST to its constituents was to consume fish from livestock ponds, which, having no influence from mining related activities and at the time, presumably would have lower concentrations of mercury in fish tissue. However, fish from livestock ponds with seemingly similar outward appearances had significant differences in accumulation in both the same species or within species of the same trophic position.The goals of the ongoing RARE project involving the Ecosystems Research Division (ORD/NERL) are twofold: 1) Determine the source and dominant pathways of methyl mercury bioaccumulation in fish tissue (presumably due to aerial deposition and/or naturally occurring sources), and 2) Make risk management recommendations to tribal members to reduce mercury exposures. The goal here is to use the results from the first objective to make future fish stocking recommendations in ponds with the least potential for bioaccumulation of methyl mercury. Sampling of biotic and environmental media during the characterization phase will be used to support the application of the USEPA Watershed Characterization System (WCS) and Mercury Cycling Model (MCM) models. USEPA and Tribal personnel completed an initial comprehensive sampling effort in the Summer of 2002. Mercury was detected in soil samples across the region, and high levels of methyl mercury were found in aquatic invertebrates, e.g., caddisflies (110 ppb), copepods (810ppb). Region VIII personnel have developed and installed a low-budget atmospheric deposition sampler on site to characterize the source term of loadings to the ponds and surrounding watersheds. Initial results confirm high levels of methyl mercury in aquatic food webs, with communities dominated by predatory zooplankton to be much more contaminated than ponds dominated by herbivorous plankton (Cladocerans). Smaller ponds appear to be at greater risk for greater methyl mercury bioaccumulation. Sample collection is ongoing in support of model development to fully characterize the fate and transport of mercury and its biomagnification in these managed aquatic ecosystems of the Sioux Tribe.

PRESENTATION	Mercury Risk Management in Livestock Ponds on the Cheyenne River Sioux Reservation	05/05/2003

Johnston, J. M., D. Hoff, R. Hoogerheide, R. Edgar, D. Wall, AND C. Ducheneaux. Mercury Risk Management in Livestock Ponds on the Cheyenne River Sioux Reservation. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	In a prior collaborative 3 year study with the Cheyenne River Sioux Tribe Department of Environmental Protection (CRST DEP), and the Agencies' Environmental Response Team, RegionVIII investigated Hg levels in fish tissues from the Cheyenne River and Lake Oahe in South Dakota. In 2000, the CRST released a fish advisory recommending less consumption of fish, especially for sensitive individuals within their population (pregnant and elderly). One mitigating risk management recommendation from the CRST to its constituents was to consume fish from livestock ponds, which, having no influence from mining related activities and at the time, presumably would have lower concentrations of mercury in fish tissue. However, fish from livestock ponds with seemingly similar outward appearances had significant differences in accumulation in both the same species or within species of the same trophic position.The goals of the ongoing RARE project involving the Ecosystems Research Division (ORD/NERL) are twofold: 1) Determine the source and dominant pathways of methyl mercury bioaccumulation in fish tissue (presumably due to aerial deposition and/or naturally occurring sources), and 2) Make risk management recommendations to tribal members to reduce mercury exposures. The goal here is to use the results from the first objective to make future fish stocking recommendations in ponds with the least potential for bioaccumulation of methyl mercury. Sampling of biotic and environmental media during the characterization phase will be used to support the application of the USEPA Watershed Characterization System (WCS) and Mercury Cycling Model (MCM) models. USEPA and Tribal personnel completed an initial comprehensive sampling effort in the Summer of 2002. Mercury was detected in soil samples across the region, and high levels of methyl mercury were found in aquatic invertebrates, e.g., caddisflies (110 ppb), copepods (810ppb). Region VIII personnel have developed and installed a low-budget atmospheric deposition sampler on site to characterize the source term of loadings to the ponds and surrounding watersheds. Initial results confirm high levels of methyl mercury in aquatic food webs, with communities dominated by predatory zooplankton to be much more contaminated than ponds dominated by herbivorous plankton (Cladocerans). Smaller ponds appear to be at greater risk for greater methyl mercury bioaccumulation. Sample collection is ongoing in support of model development to fully characterize the fate and transport of mercury and its biomagnification in these managed aquatic ecosystems of the Sioux Tribe.

PRESENTATION	A Comprehensive Nonpoint Source Field Study for Sediment, Nutrients and Pathogens in the South Fork Broad River Watershed, Georgia	05/05/2003

Smith, C. N., D. L. Spidle, P. D. Smith, B. E. Kitchens, M. J. Cyterski, L. M. Prieto, D. C. Bouchard, K. Wolfe, H. P. Kollig, L. Smith, S. Senter, M. Flexner, T. R. Cavinder, AND B. Johnson. A Comprehensive Nonpoint Source Field Study for Sediment, Nutrients and Pathogens in the South Fork Broad River Watershed, Georgia. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	There is an urgent need for EPA to develop protocols for establishing Total Maximum Daily Loads (TMDLs) in streams, lakes and estuaries. A cooperative TMDL field data collection project between ORD and Region 4 is ongoing in the South Fork Broad River Watershed (SFBR), a 245.18 square mile area with 337.32 stream miles located in the Savannah River Basin that consists of intensive storm event stream sampling. In 1998, the State of Georgia listed the SFBR watershed as biologically impaired (i.e. 303. (d) list), but the source of contamination was unknown. This project is 1) developing sampling protocols to measure the TMDL of bedload and suspended sediment, nutrients (nitrate, ammonia, ortho phosphorus and total phosphorus) total organic carbon and pathogens (fecal coliform, E. coli, and enterococci), and 2) developing a comprehensive database to develop, field test and apply mathematical models and protocols for calculating the TMDLs in this watershed and its tributaries in a field setting not available elsewhere in the U.S. Six stream sites have been highly instrumented with specialized monitoring equipment (ISCO water samplers, YSI multi-probes and cableway sampling systems) for collecting data before, during and after storm events. A weather station located in the watershed is collecting meteorological data and additional precipitation data are being collected from seven other sites. Stream hydrographic data are being collected for stage and velocity to develop stage-discharge relationships for each sampling site including a continuous real-time gaging station at the watershed outlet. When the study is complete, over three hundred stream cross-sectional sites will be surveyed and samples analyzed for characterization (particle size and carbon content by loss on ignition). Prior to the SFBR project, there was limited scientific data available to support TMDL development. The results of the SFBR project will accomplish the following: 1. Provide a comprehensive dataset that allows for the development, field testing, and calibration of mathematical models addressing water quality and quantity in a watershed. The dataset created in SFBR will be unique; there is no other study site with a comparable collection of data in the U.S. 2. Provide robust data and models that establish a scientific basis for clean sediment and pollutant TMDLs 3. Provide a means of testing field and laboratory instrumentation, methodolgy, and development of standard operating procedures for sampling protocols, sample processing and analytical analyses 4. Develop procedures for site selection, field instrumentation, maintenance and servicing, frequency of sampling, data requirements, safety and QA

PRESENTATION	A Comprehenisve Nonpoint Source Field Study for Sediment, Nutrients and Pathogens in the South Fork Broad River Watershed in Northeast Georgia	05/05/2003

Smith, C. N., D. L. Spidle, F. E. Stancil, P. D. Smith, B. E. Kitchens, H. P. Kollig, L. Smith, S. Senter, M. J. Cyterski, L. M. Prieto, D. C. Bouchard, K. Wolfe, M. Flexner, T. R. Cavinder, AND B. Johnson. A Comprehenisve Nonpoint Source Field Study for Sediment, Nutrients and Pathogens in the South Fork Broad River Watershed in Northeast Georgia. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	There is an urgent need for EPA to develop protocols for establishing Total Maximum Daily Loads (TMDLs) in streams, lakes and estuaries. A cooperative TMDL field data collection project between ORD and Region 4 is ongoing in the South Fork Broad River Watershed (SFBR), a 245.18 square mile area with 337.32 stream miles located in the Savannah River Basin that consists of intensive storm event stream sampling. In 1998, the State of Georgia listed the SFBR watershed as biologically impaired (i.e. 303. (d) list), but the source of contamination was unknown. This project is 1) developing sampling protocols to measure the TMDL of bedload and suspended sediment, nutrients (nitrate, ammonia, ortho phosphorus and total phosphorus) total organic carbon and pathogens (fecal coliform, E. coli, and enterococci), and 2) developing a comprehensive database to develop, field test and apply mathematical models and protocols for calculating the TMDLs in this watershed and its tributaries in a field setting not available elsewhere in the U.S. Six stream sites have been highly instrumented with specialized monitoring equipment (ISCO water samplers, YSI multi-probes and cableway sampling systems) for collecting data before, during and after storm events. A weather station located in the watershed is collecting meteorological data and additional precipitation data are being collected from seven other sites. Stream hydrographic data are being collected for stage and velocity to develop stage-discharge relationships for each sampling site including a continuous real-time gaging station at the watershed outlet. When the study is complete, over three hundred stream cross-sectional sites will be surveyed and samples analyzed for characterization (particle size and carbon content by loss on ignition). Prior to the SFBR project, there was limited scientific data available to support TMDL development. The results of the SFBR project will accomplish the following:1. Provide a comprehensive dataset that allows for the development, field testing, and calibration of mathematical models addressing water quality and quantity in a watershed. The dataset created in SFBR will be unique; there is no other study site with a comparable collection of data in the U.S. 2. Provide robust data and models that establish a scientific basis for clean sediment and pollutant TMDLs. 3. Provide a means of testing field and laboratory instrumentation, methodolgy, and development of standard operating procedures for sampling protocols, sample processing and analytical analyses. 4. Develop procedures for site selection, field instrumentation, maintenance and servicing, frequency of sampling, data requirements, safety and QA.

PRESENTATION	Stream Fish Habitat Suitability and the Risk of Population Decline	05/05/2003

Rashleigh, B. Stream Fish Habitat Suitability and the Risk of Population Decline. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Over half of the streams in the Mid-Atlantic Highlands have fish communities that are in fair or poor condition, and the EPA concluded that physical habitat alteration represents the greatest potential stressor across this region. A quantitative method for relating habitat quality to biological endpoints is needed in order for managers and researchers to understand the link between this stressor and fish community condition. Here, a model of fish habitat suitability that was developed by the U.S. Fish and Wildlife Service is applied in this region. Longnose dace is used as an indicator species for the most sensitive component of the fish community. Habitat suitability for longnose dace is determined by stream depth, temperature, substrate type, and natural cover and shelter. Available stream data are used to calculate an overall measure of habitat suitability. The measure of habitat suitability is then incorporated into a stage-structured population dynamics model for longnose dace. It is assumed that habitat suitability affects the carrying capacity for fish in these streams. The longnose dace population model incorporates uncertainty to provide estimates of population size through time. The outcome of this work is a modeling tool that can forecast the risk of fish population decline, in response to habitat alteration, over various time frames. The general result from this work is important because it provides managers with a method to quantitatively incorporate biological endpoints into decision-making for TMDLs. Specific results for the Mid-Atlantic Highlands can allow managers, in particular the Canaan Valley Institute, an EPA partner, to evaluate the response of biological endpoints to stream management alternatives and restoration scenarios for streams of this region.

PRESENTATION	Population Decline in Stream Fish	05/05/2003

Rashleigh, B. Population Decline in Stream Fish. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Over half of the streams in the Mid-Atlantic Highlands have fish communities that are in fair or poor condition, and the EPA concluded that physical habitat alteration represents the greatest potential stressor across this region. A quantitative method for relating habitat quality to biological endpoints is needed in order for managers and researchers to understand the link between this stressor and fish community condition. Here, a model of fish habitat suitability that was developed by the U.S. Fish and Wildlife Service is applied in this region. Longnose dace is used as an indicator species for the most sensitive component of the fish community. Habitat suitability for longnose dace is determined by stream depth, temperature, substrate type, and natural cover and shelter. Available stream data are used to calculate an overall measure of habitat suitability. The measure of habitat suitability is then incorporated into a stage-structured population dynamics model for longnose dace. It is assumed that habitat suitability affects the carrying capacity for fish in these streams. The longnose dace population model incorporates uncertainty to provide estimates of population size through time. The outcome of this work is a modeling tool that can forecast the risk of fish population decline, in response to habitat alteration, over various time frames. The general result from this work is important because it provides managers with a method to quantitatively incorporate biological endpoints into decision-making for TMDLs. Specific results for the Mid-Atlantic Highlands can allow managers, in particular the Canaan Valley Institute, an EPA partner, to evaluate the response of biological endpoints to stream management alternatives and restoration scenarios for streams of this region.

PRESENTATION	Trace Gas Concentrations in Streams Early Warning Indicators of Stream Impairment?	05/05/2003

Burke Jr., R. A. Trace Gas Concentrations in Streams Early Warning Indicators of Stream Impairment? Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Surface water contamination and resultant impairment of aquatic ecosystem functioning are serious environmental problems, caused in large part by land use changes and excess organic waste inputs associated with agriculture and residential and industrial development. Headwater streams are critical components of river networks, comprising ~95% of the total number of stream channels and ~75% of the total stream channel length in the US, and they frequently exhibit high rates of biogeochemical cycling. Because of their small size, headwater stream ecosystem function is easily impaired by human disturbance of the watershed, riparian zone, or channel. Headwater streams and their watersheds provide valuable ecosystem services such as organic matter processing which provides important resources to downstream ecosystems such as lakes and rivers. As watersheds are increasingly developed to meet human demands, the development of effective and easily measured indicators of watershed impairment will become increasingly crucial. The degrees to which stream concentrations of the biologically reactive trace gases nitrous oxide, carbon dioxide, and methane deviate from atmospheric equilibrium are useful indicators of overall watershed organic matter decomposition rates and metabolism (e.g., anoxic vs anaerobic, nitrification vs. denitrification). Because stream ecosystem function can be impaired by excess inputs of organic wastes, trace gas concentrations should provide valuable information about stream ecosystem function. Discussion of the need for effective indicators of organic waste and nutrient loadings to watersheds impacted by human activities with Region 4 and Office of Water (OW) personnel stimulated development of this research activity and it is anticipated that further development of these indicators will be made in collaboration with personnel from OW and various EPA Regions. Results of a one-year study of 17 Georgia Piedmont headwater streams suggest that: (1) total dissolved nitrogen (TDN), dissolved organic carbon (DOC), and dissolved concentrations of nitrous oxide and methane in streams are all effective indicators of stream impairment by nutrients and organic wastes from septic tanks and/or animal manure; and (2) the trace gas concentrations are far more sensitive indicators that respond to much lower levels of nutrient and organic waste contamination than do the bulk parameters TDN and DOC. Elevated levels of nitrous oxide and methane in streams appear to be viable early warning indicators of incipient stream impairment and these indicators, largely being developed through this research, may have great value to water quality managers and regulators in EPA Program Offices and Regions as well as those in state and local governments.

PRESENTATION	Development of Modeling Protocols for Use in Determining Sediment Tmdls	05/05/2003

Hayter, E. J. Development of Modeling Protocols for Use in Determining Sediment Tmdls. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Modeling protocols for use in determining sediment TMDLs are being developed to provide the Office of Water, Regions and the States with assistance in determining TMDLs for sediment impaired water bodies. These protocols will supplement the protocols developed by the Office of Water (U.S. EPA 1999) for determining sediment TMDLs. Specifically, the modeling protocols will provide additional guidance in determining sediment TMDLs for cases where a numerical model must be used to simulate sediment transport and fate to quantify the impacts of proposed BMPs, etc. in reducing the detrimental effects of clean sediments on the impaired body of water. These protocols will describe the following: criteria for deciding when a sediment transport model should be used in developing a sediment TMDL; criteria for choosing the appropriate sediment transport and fate model to use for a given impaired water body; procedures to use for performing both model calibration and confirmation; data requirements for the recommended model; and recommended procedures for collecting/measuring the required data. Also included in the modeling protocols will be the testing of new sediment transport and fate models using an extensive data set collected on a 12-mile reach of the Housatonic River in western Massachusetts. The new models to be tested are EFDC-1D, GSTARS2c, CSED-2D (ver. 2.0), and EFDC. The modeling protocols along with the new sediment transport and fate models (and the supporting documentation and post-processors) will be given to the Office of Water for review and distribution to the Regions and States. It is anticipated that the results from this research will be useful to the Office of Water, the Regions and States in evaluating the effectiveness of proposed BMPs in reducing the detrimental impact of clean sediments on the nation's streams, rivers, lakes, reservoirs, and estuaries.

PRESENTATION	Integrating the Science and Technology of Environmental Assessment Across Federal Agencies	05/05/2003

Laniak, G. F. Integrating the Science and Technology of Environmental Assessment Across Federal Agencies. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Seven Federal Agencies are conducting collaborative research to provide the next generation of environmental models for analyzing complex multimedia, multi-stressor contamination problems. Among the primary objectives of the Memorandum of Understanding (MOU) are 1) to provide a mechanism for the cooperating Federal Agencies to pursue a common technology in multimedia environmental modeling with a shared scientific basis, 2) to reduce redundancies and improve the common technology through exchange and comparisons of multimedia environmental models, software and related databases, 3) to exchange information related to multimedia environmental modeling tools and supporting scientific information for environmental risk assessments, protocols for establishing linkages between disparate databases and models, and development and use of a common model-data framework, and 4) to facilitate the establishment of working partnerships among the cooperating Federal Agencies' technical staff in order to enhance productivity and mutual benefit through collaboration on mutually-defined research studies. The collaborating agencies are (in addition to EPA/ORD): 1. The United States Nuclear Regulatory Commission, Office of Nuclear Regulatory Research 2. The United States Army Corps of Engineers, Engineer Research and Development Center 3. The United States Department of Energy, Office of Science and Technology 4. The United States Department of Interior, U.S. Geological Survey 5. The United States Department of Agriculture, Agricultural Research Service 6. The United States Department of Agriculture, Natural Resources Conservation Service The MOU is organized with a Steering Committee and several technical workgroups. The Steering Committee includes senior officials from each Agency and the workgroups are comprised of researchers from each Agency. To date workgroups have developed research plans (approved by the Steering Committee), sponsored sessions at professional conferences, and conducted workshops targeting details of potential collaborative projects. The current workgroups include : 1. Software System Design and Implementation for Environmental Modeling 2. Uncertainty Analysis and Parameter Estimation 3. Distributive Watershed / Water Quality Modeling 4. Reactive Solute Transport

PRESENTATION	Using Subsurface Transport Research to Achieve Agency Outcomes	05/05/2003

Weaver, J. W., J. E. Haas, AND M. C. Small. Using Subsurface Transport Research to Achieve Agency Outcomes. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	Gasoline leaks from underground storage tanks can cause ground water contamination because there are a number of organic chemicals in gasoline. These chemicals have varying properties that influence how far contamination extends from the release. Research on transport of these chemicals has provided direct input to Agency decision-making or support for program implementation. Four examples of the influence of this work will be given. In 1998, EPA convened a blue-ribbon panel to investigate all aspects of Methyl tert-butyl ether (MTBE) usage as a gasoline additive. Research done in collaboration with the New York State Department of Environmental Conservation (NYSDEC) provided the panel with detailed data on MTBE transport from sites on Long Island, which is one area of the country with significant impacts to ground water from leaking tank sites. In a later assessment of MTBE usage, the Agency pondered the question of reducing MTBE content in gasoline from 11% to 3%. A transport analysis, that used ORD developed models concluded that concentrations in ground water would indeed be reduced in proportion to the reduction in MTBE content in gasoline, but that the extent of contamination would be reduced by a much smaller amount. A company had an idea for a suite of unique tracers to be used in tank testing, but the environmental impacts of these chemicals were unknown. ORD provided an analysis of how the tracers would behave during leaks, by performing a comparative analysis MTBE and benzene transport. This allowed the Agency to make a decision on the use of the tracers with information on how these tracers would impact ground water and other environmental media (air). The most publicized application of this research to fuel problems is the OnSite on-line calculator web site at www.epa.gov/athens/onsite. The calculators were developed for State Agency regulators and private sector consultants and include practical, and sometimes simple, calculations, models and unit conversions. The site also conveys research results that can improve practice in this field. Examples where this is known to have occurred are with recharge-driven diving of plumes, effective solubility of chemicals in mixtures and input parameter-induced model uncertainty.

PRESENTATION	Louisiana Environmental Modeling System for Hypoxia Related Issues	05/12/2003

Russo, R. C. AND R. F. Carousel. Louisiana Environmental Modeling System for Hypoxia Related Issues. Presented at Seventh International Symposium on Fish Physiology, Toxicology, and Water Quality, Tallinn, Estonia, May 12-15, 2003.
Abstract:	An environmental assessment tool to evaluate the impacts of nonpoint source (NPS) pollutants discharged from Mississippi River basins into the Gulf of Mexico and to assess their effects on receiving water quality will be described. This system (Louisiana Environmental Modeling System (LEMS) will build upon a joint effort by the U.S. Navy and EPA called the Northern Gulf Littoral Initiative (NGLI). This LEMS modeling system will expand on the state-of-the-art monitoring and coastal forecasting system developed for the Northern Gulf of Mexico. The modeling domain will be moved to the western side of Louisiana to encompass the hypoxic zone and the near coastal region. The modeling system will be linked to form a comprehensive modeling system for evaluating NPS discharges. The project should provide a technology that does not currently exist for the hypoxic zone, that combines a three-media model with an advanced coastal hydrodynamic and water quality model. This model to evaluate NPS discharges is important because of the impact on water quality including the formation of a hypoxic (dead) zone off the Louisiana coast line. The models mentioned above will be refined and coupled to produce the LEMS system, then applied to assess the water quality effects associated with NPS discharges on a larger scale in the Louisiana coastal regions of the Gulf of Mexico. Coupling the three-media model with the coastal hydrodynamic and water quality model will provide an innovative and useful approach to evaluate the impact of NPS discharges as they are transported and transformed through land runoff, surface stream networks, groundwater pathways and coastal tidal processes. The modeling system will help in defining the magnitude of reduction in NPS discharges to the Gulf of Mexico required to obtain a long-term decrease in the extent of hypoxia formation in the Gulf of Mexico.

PRESENTATION	Testing a Beach Bacteria Model in Lake Michigan and Southern California	09/22/2003

Frick, W. E., A. P. Dufour, T. Khangaonkar, AND M. Molina. Testing a Beach Bacteria Model in Lake Michigan and Southern California. Presented at Oceans 2003 Marine Technology and Ocean Science Conference, San Diego, CA, September 22-26, 2003.
Abstract:	Beach closures due to high bacterial concentrations deprive the public and disrupt the tourist industry. Almost half the Lake Michigan beaches are closed more than 10% of the time. In 1999 the six-mile long beach in Huntington Beach, California was closed in July and August. Due to long growth times, bacteria-related closures are generally based on samples collected 48 hours or more previously, so that many closures may not be justified by current conditions. Monitoring frequency can delay re-openings. Furthermore, bacteria have both human and animal origins, with different inherent risk to humans. Tests using polymerase chain reactions (PCR) that can determine criterion-level concentrations in less than two hours are coming into use and work is ongoing on determining bacterial origins based on DNA fingerprinting. These technologies will help protect the public, however, predictive models promise to help health officials post warnings in advance and, even better, prevent closures by helping sewage treatment plant managers apply optimal preventive disinfection, automatically metering or rerouting releases from combined sewer overflow retention basins, etc.. An existing version of the proposed model has been used to simulate the movement of the Orange County Sanitation District, California outfall plume, a major source. The results suggest the offshore waste field is generally not connected to high beach bacteria concentrations, an issue further addressed by the revised model by the addition of a line source, simulating beaches. In addition to revisiting the Orange County example, the new model is tested in southern Lake Michigan using 2002 West Beach (Indiana Dunes National Seashore) bacteria data, available current meter measurements, wind and other meteorological data, and hydrological and loading records of Burns Ditch, a major stream draining the area. More realistic results portraying near-shore and major source contributions are described. Combined with advances in species differentiation and pathogen identification (that will generally be associated with human sources), modeling may ultimately help to limit beach closures to events posing actual risk to humans.

PRESENTATION	Disinfection By-Products of Health Concern in Drinking Water: Results of a U.S. Nationwide Occurrence Study	08/31/2003

Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, H. S. Weinberg, R. Chinn, M. J. Sclimenti, S. J. Pastor, AND G. D. Onstad. Disinfection By-Products of Health Concern in Drinking Water: Results of a U.S. Nationwide Occurrence Study. Presented at International Mass Spectrometry Conference, Edinburgh, Scotland, August 31 - September 5, 2003.
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. Environmental Protection Agency (EPA) has regulated several DBPs; however, most DBPs have not been tested for adverse health effects due to the high costs involved. In order to prioritize new DBPs for health effects testing, we initiated a Nationwide Occurrence Study to quantify 'high priority' DBPs (those predicted by toxicology experts to possibly have an adverse health effect) to determine how often they occur and at what levels. The fate and transport of these DBPs in the distribution system was also studied, and new DBPs were identified. Drinking water samples were collected across the United States from 12 plants that use chlorine, ozone, chlorine dioxide, and/or chloramines for disinfection. Locations were chosen to provide waters that contain low and high bromide levels, different pH conditions, and different natural organic matter (NOM) levels (NOM and bromide are DBP precursors; pH impacts the formation and stability of many DBPs). For comparison purposes, regulated and Information Collection Rule DBPs were quantified along with the high priority DBPs. Drinking water samples were collected at the treatment plants and in the distribution systems. Quantitation methods developed involved various extraction, derivatization, and detection methods (including solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, and purge-and-trap with GC/electron capture detection or GC/MS). For identifying new DBPs, GC with low and high resolution electron ionization-MS and chemical ionization-MS were used. Many of the high priority DBPs were found in drinking waters across the United States. High priority DBPs identified and quantified include 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and brominated forms of MX (the so-called BMXs), iodo-trihalomethanes, other halomethanes, halonitromethanes, haloacids, haloacetaldehydes, haloacetonitriles, haloketones, haloacetates, haloamides, and a few non-halogenated DBPs. In previous limited studies, MX was found at levels up to 60 parts-per-trillion (ng/L); however, in this study, MX reached levels of 300-400 ng/L at certain locations. Iodinated DBPs, including iodo-trihalomethanes, were also detected in many drinking waters sampled, even those with relatively low bromide (and probably low iodide) levels. Although chloramines are used to reduce trihalomethane formation, previous bench-scale studies indicated that ammonia addition before chlorination (to form chloramines) could favor the formation of iodinated DBPs. In this full-scale study, iodo-trihalomethanes were highest at a plant that used chloramines only for disinfection. Also while ozone and chloramines generally control the formation of trihalomethanes and other trihalo species, some dihalo species (such as dihaloaldehydes) were higher at plants using ozonation and/or chloramination. Another important finding was the discovery of iodo-acids. Iodo-acids have never been reported previously for any disinfectant. Five iodo-acids (iodoacetic acid, iodobromoacetic acid, iodobromopropenoic acid (2 isomers), and 2-iodo-3-methylbutenedioic acid) were identified in drinking water from a plant in the Southwest that used chloramine disinfection for high-bromide source waters. Many new brominated haloacids were also identified in drinking waters from several states. Brominated DBPs are important, as current toxicology (and some recent epidemiology) studies suggest that certain brominated DBPs may be of higher health concern than the chlorinated species.

PRESENTATION	Enantiomer Fractions of Chlordane Compounds in Sediment Samples from U.S. Geological Survey Sites in Lakes, Rivers and Reservoirs	08/24/2003

Ulrich, E. M., C. S. Wong, S. A. Rounds, P. C. VanMetre, J. T. Wilson, A. W. Garrison, AND W. T. Foreman. Enantiomer Fractions of Chlordane Compounds in Sediment Samples from U.S. Geological Survey Sites in Lakes, Rivers and Reservoirs. Presented at 23rd International Symposium on Halogenated Organic Pollutants and Persistent Organic Pollutants, Boston, MA, August 24-29, 2003.
Abstract:	The environmental behavior of the enantiomers of cis- and trans-chlordane has been the topic of much research since the first chiral separations on cyclodextrin gas chromatography (GC) columns. When chlordane is manufactured, it is always a racemic mixture (equal portion of two enantiomers). As the compounds move through the environment, physical processes, such as volatilization, photolysis, and OH radical reactions, are not likely to change the enantiomer signature. However, biological processes, including uptake, depuration, and metabolism often are mediated by chiral molecules, such as enzymes that cause changes in the enantiomer signature. Enantiomer behavior of chlordane has been reported in biota, soil, water, and air. Enantiomer signatures have been used to trace chlordane sources from soil in the Midwest, to air above the soil, and to air near the Great Lakes. Additionally, evidence of biological degradation has been shown through enantiomer signatures. To date there have been no reports of chlordane enantiomer trends in sediment. Previous studies of toxaphene congeners and PCB atropisomers in sediment samples have shown interesting enantioselective behavior. Because sediment cores are used as a historical record of contaminant deposition, it is important to ensure that the record is accurate and has not been changed by biological degradation. The goal of this research is to document the enantiomeric behavior of chlordane compounds in sediment samples. In addition to sediment cores, surficial and suspended sediment samples will help determine a likely source of contamination to sediment. Trends are analyzed with sediment type, location, deposition date, and concentration for various chlordane compounds.

PRESENTATION	Modifications of Wasp for Simulating Periphyton Dynamics	11/16/2003

Wool, T. A., R. B. Ambrose Jr., J. L. Martin, S. Davie, AND W. Anderson. Modifications of Wasp for Simulating Periphyton Dynamics. Presented at Total Maximum Daily Load 2003, Chicago, IL, November 16-18, 2003.
Abstract:	Conventional water quality models that are in current use today for the development of TMDLs and waste load allocations usually use dissolved oxygen, nutrient concentrations and algal growth as indicators to water health. In shallow streams and rivers, water health can be controlled by presence of fixed plants, such as macrophytes to periphyton. As water resource managers and regulators develop nutrient management strategies for these waterbodies it becomes difficult to determine what types of nutrient controls need to be put in place to control the presence, abundance and influence of periphyton on water quality. This paper looks at the process of adding periphyton algorithms to the Water Quality Analysis Simulation Program (WASP). The Water Quality Analysis Simulation Program- (WASP6), an enhancement of the original WASP (DiToro et al., 1983; Connolly and Winfield, 1984; Ambrose, R.B. et al., 1988). This model helps users interpret and predict water quality responses to natural phenomena and man made pollution for various pollution management decisions. WASP is a dynamic compartment-modeling program for aquatic systems, including both the water column and the underlying benthos. The time varying processes of advection, dispersion, point and diffuse mass loading, and boundary exchange are represented in the basic program. The paper will discuss the selection and development process for the periphyton routines and how they are incorporated into the model. A discussion will be presented on the type of data that will be required to use the algorithms in a modeling study. Finally, a series of case studies will be presented to illustrate the impact of considering periphyton in a modeling study and how it translates into point and nonpoint source load allocations in nutrient TMDLs

PRESENTATION	Interactions of Climate Change and UV Radiation as Corals Stressors	05/07/2003

Zepp, R. G. Interactions of Climate Change and UV Radiation as Corals Stressors. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	The Importance of Proper Intensity Calibration for Raman Analysis of Low-Level Analytes in Water	10/19/2003

Melkowits, R. B., T. L. Williams, AND T. W. Collette. The Importance of Proper Intensity Calibration for Raman Analysis of Low-Level Analytes in Water. Presented at Federation of Analytical Chemistry and Spectroscopy Societies Conference, Ft. Lauderdale, FL, October 19-23, 2003.
Abstract:	Modern dispersive Raman spectroscopy offers unique advantages for the analysis of low-concentration analytes in aqueous solution. However, we have found that proper intensity calibration is critical for obtaining these benefits. This is true not only for producing spectra with accurate intensity ratios, but also for consistently meeting the signal-to-noise requirement for this demanding application. While the former has received considerable attention in the literature, the latter has received far less. We will discuss the development and application of a technique for intensity calibration that has been particularly convenient in our laboratory. One common method of intensity calibration relies on collecting the spectrum of a regulated light source with a traceable output of intensity versus wavelength. A spectrum collected from this source is stored and used to correct the instrument factors that distort the spectra of samples that are subsequently collected. These factors include the wavelength dependence of the quantum efficiency, and the pixel-to-pixel variation, of the CCD detector, as well as the varying transmission efficiency of the instrument. However, this approach has certain limitations. For example, the spectrum of the light source must be collected in close temporal proximity to the sample spectrum if any instrument factors are changing, such as those due to temperature fluctuations or realignment. Furthermore, the spatial orientation and geometry of the calibration source and the Raman sample are dissimilar. Our simple method shares the benefits of this convenient calibration method, but suffers considerably less from these limitations. The Raman spectrum of an analyte in water is generally produced by subtracting a water spectrum from a sample spectrum that was collected sequentially. If data collection and subtraction are conducted judiciously, the CCD pixel-to-pixel variation and other instrument factors are adequately corrected by this simple step, but the resultant analyte spectrum will exhibit biased peak intensities because the CCD quantum efficiency variation is uncorrected. However, this can be corrected by multiplying the analyte spectrum by a severely smoothed light source spectrum that has been ratioed with the source's traceable output function. Consequently, only one light source spectrum is necessary for long-term use on a single instrument.

PRESENTATION	Simplified Method for Extracting Bound Pesticides from Avian Serum	11/09/2003

Ellington, J. J., J. J. Evans, AND S. E. Sundberg. Simplified Method for Extracting Bound Pesticides from Avian Serum. Presented at 24th Annual Society of Environmental Toxicology and Chemistry Meeting, Austin, TX, November 9-13, 2003.
Abstract:	A simple solid-phase extraction (SPE) method was developed to extract organochlorine pesticides (OCs) and persistent organic pollutants (POPs) from avian serum. In this method, a 1-mL serum sample fortified with two levels of OCs or POPs was treated with 8M urea or 4M urea and 4M guanidine hydrochloride (GH) to denature serum proteins without precipitation. Urea or the urea and the GH-treated serum was applied to a washed 30-mg Oasis HLB cartridge to extract fortified pesticides from the serum sample by gravity flow. The cartridge was rinsed with three 1-mL volumes of deionized water also by gravity flow and dried for ten minutes under gentle vacuum. POPs and OCs were eluted from the cartridge into a 2-mL gas chromatography (GC) sample vial with 1 mL methylene chloride by gravity flow, and residual methylene chloride was removed from the cartridge using gentle vacuum. A small amount of the methylene chloride was not recovered. Therefore, the vial contents were brought to a total volume of 1 mL using a Hamilton 1000 microliter syringe. Lipids were not retained on the cartridge; thus, no additional fat cleanup was necessary. POPs and OCs were separated by GC, quantified by electron capture detection and verified by GC mass spectrometry. Pesticide recoveries ranged from 73-104%. Although the 1-mL sample size was used for method development, avian serum volumes as low as 20 microliter have been analyzed in this laboratory using this method. This method is faster (< 1hr), easier (two solvents), and as efficient if not more efficient than previously developed SPE and liquid-liquid extraction (LLE) methods for separating pesticides from serum.

PRESENTATION	The Enantiomers of Chiral Pollutants Pose Different Risks	11/09/2003

Garrison, A. W., W. J. Jones, T. E. Wiese, B. J. Konwick, M. A. Tapper, AND M. K. Morgan. The Enantiomers of Chiral Pollutants Pose Different Risks. Presented at 24th Annual Society of Environmental Toxicology and Chemistry Meeting, Austin, TX, November 9-13, 2003.
Abstract:	In order to make more accurate risk assessments for chiral pesticides and other pollutants, it is necessary to understand the relative persistence and effects of their enantiomers. A major effort is underway in the USEPA to measure exposure in the home environment to various pesticides and PCB congeners. As an adjunct to this study, extracts of various samples previously shown to contain target pesticides and PCBs were analyzed for the enantiomers of certain of these which are chiral. Preliminary results show that PCB 95 occurs enantioselectively in house dust but not in yard soil: enantiomer ratios (ER) range from 0.51 to 0.98 with an average ER of 0.77 in floor dust compared to near racemic values in yard soil. The toxic effects of enantiomers have been scarcely examined. The effects of the enantiomers of cis-chlordane to the reproduction and survival of potworms (Enchytraeus crypticus) will be reported; these tests are currently underway. In addition, a summary of test results for various toxicity endpoints including Ceriodaphnia toxicity tests and in vitro endocrine activity determinations for the racemate and the separate enantiomers of the modern insecticide fipronil will be presented and compared with data on fipronil enantioselective microbial degradation. Preliminary results indicate high toxicity of racemic fipronil to Ceriodaphnia dubia with an LC50 of 25ug/L. While no estrogen activity was observed for the fipronil racemate or enantiomers, the racemate and (-) enantiomer were shown to have significant androgen receptor and progesterone receptor antagonist activity. Regarding microbial degradation, preliminary studies show that the direction of enantioselectivity can be different in soils with apparently different redox character.

PRESENTATION	Shedding Light on Corals Health: Interactions of Climate Change and Solar Radiation With Bleaching	06/18/2003

Zepp, R. G. Shedding Light on Corals Health: Interactions of Climate Change and Solar Radiation With Bleaching. Presented at Corals Reefs, Climate, and Coral Bleaching Workshop, Oahu, HI, June 18-20, 2003.
Abstract:	Coral bleaching and declines in coral reef health in recent years have been attributed in part to processes driven by UV and/or visible light. For coral assemblages, exposure to UV light is often an unavoidable consequence of having access to visible (photosynthetically active) radiation. UV exposure can potentially affect corals by damage to DNA or by damage to other target molecules, including proteins that are part of the photosynthetic system. Changes in environmental conditions such as increased temperature or other factors can influence adverse responses of corals to UV and visible light by altering mechanisms that protect the corals from light damage. In addition to effects on responses of corals to UV light, changes in environmental conditions can also have pronounced effects on the nature and amount of light that reaches the surface of corals, especially in the UV region. Changes in atmospheric composition, especially in total ozone, have important effects on the UV-B (280 - 315 nm) part of solar radiation that reach the ocean surface. In addition, changes in UV exposure can stem from shifts in UV-absorbing dissolved and particulate organic matter in the ocean. Recent research has shown that the colored component of dissolved organic matter (CDOM) controls the penetration of solar UV and blue radiation into waters over the many coral reefs. Light exposure of the CDOM in the upper ocean causes it to decompose and the resulting decrease in UV light absorption can enhance UV exposure of coral reefs, especially under well-stratified conditions such as those that develop during El Nino events. The CDOM is introduced to the water by decomposition of aquatic plants (e.g. algal detritus and seagrasses) and by runoff from nearby terrestrial ecosystems. Changes in salinity and land use, coupled with precipitation, sea level and current changes, can have important effects on CDOM sources that affect corals light exposure.

PRESENTATION	Drift of Pesticides: Developing An Integrated Exposure Tool	06/18/2003

Bird, S. L. Drift of Pesticides: Developing An Integrated Exposure Tool. Presented at Seminar at OPPTS, Washington, DC, June 18-19, 2003.
Abstract:	Off-site drift of pesticides from agricultural sites is a major source of inadvertant pesticide exposure. AgDRIFT/AGDISP is a near-field modeling technology (<1000 m) used to evaluate primary drift from a single application from a single field during neutral atmospheric conditions over level terrain with uniform surface characteristics. This technology is a major improvement for OPP in estimating exposure and gives them the ability to evaluate buffer zones, a range of application variables, and some environmental conditions. However, as it stands now many limitations exist in meeting OPP's total exposure assessment needs for pesticide drift. A new ORD research initiative is designed to develop and test modeling capabilities that will provide OPP, Regions, States, and other entities with the capability of addressing exposure from off-site drift in a comprehensive manner with quantifiable uncertainty. This seminar describes the current state of regulatory spray drift modeling technology and the current and proposed research efforts to develop a comprehensive tool.

PRESENTATION	Observations of Enantioselectivity in the Fate, Persistence and Effects of Modern Pesticides	08/25/2003

Garrison, A. W., W. J. Jones, T. E. Wiese, J. W. Washington, J. L. Jarman, AND J. Avants. Observations of Enantioselectivity in the Fate, Persistence and Effects of Modern Pesticides. Presented at 23rd International Symposium on Halogenated Organic Pollutants and Persistent Organic Pollutants, Boston, MA, August 24-29, 2003.
Abstract:	Chiral pollutants exist as 2 (or more) species, -- enantiomers -- that are non-superimposable mirror images of each other. Enantiomers have identical physical and chemical properties except when they interact with enzymes or other chiral molecules; then they usually react selectively. This enantioselectivity often results in different rates of microbial/biological transformation, differences in toxicity of the two enantiomers, and differences in activities toward target species. Up to 25% of pesticides are chiral molecules, and almost all are manufactured and applied as their racemates, mixtures of equal amounts of the enantiomers. Recently, however, the agrochemical industry and government regulators are beginning to take enantioselectivity into account. For example, the (R)-(+)-enantiomer of dichlorprop (as well as the (R)-enantiomers of all the phenoxypropionic acid herbicides) is the herbicidally active species, while the (S)-(-)-enantiomer is inactive; so, to reduce the amount of herbicide used and avoid the possibility of the unnecessary enantiomer causing some adverse impact, several European countries have decreed that only the (R)-enantiomers will be used. In addition, the two (S)-enantiomers of metolachlor, one of the most widely used herbicides in the USA, are nine times more herbicidally active than the (R)-enantiomers, so its manufacturer successfully petitioned the EPA for registration of a formulation enriched to contain 88% of the (S)-enantiomers . This allows a 35% reduction in the amount of the herbicide applied, with the same effect. It seems obvious that the enantiomers of chiral pesticides should be treated as separate compounds and that accurate environmental and human risk assessments require an understanding of the relative persistence and effects of each enantiomer. This paper emphasizes results of recent research on the fate and effects of enantiomers of specific chiral pesticides in use today; the so-called modern pesticides.

PRESENTATION	Do You Know What's in Your Drinking Water? Identifying the Chemical By-Products You Can't See	06/20/2003

Richardson, S. D. Do You Know What's in Your Drinking Water? Identifying the Chemical By-Products You Can't See. Presented at Northeast Georgia Engineers Meeting, Athens, GA, June 20, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Lust on-Line Calculator Introduction	07/24/2003

Weaver, J. W. Lust on-Line Calculator Introduction. Presented at RevTech Conference, Pittsburg, PA, July 22--24, 2003.
Abstract:	EPA has developed a suite of on-line calculators to assist in performing site assessment and modeling calculations for leaking underground storage tank sites (http://www.epa.gov/athens/onsite). The calculators are divided into four types: parameter estimation, models, scientific demos and unit conversions. Parameter estimation calculators are used to estimate gradients, chemical parameters, retardation factors, multiphase partitioning and effective solubilities. Simple models are included to perform transport analyses which include transport of contaminants to receptors, diving of plumes due to recharge, and estimates of uncertainty in model outcomes. Scientific demos illustrate concepts concerning subsurface flow and transport, including for example the effects of borehole dilution on observed concentrations. Unit conversions for parameters unique to this field (hydraulic conductivity, Henry's law constants, rate constants) are included as aids to correct site assessment and analysis. Since their beginning in 1999, the calculators have proven to be a useful tool as evidenced by steady increase in their usage. EPA is currently adapting the calculators to address a wider variety of problems by including parameter values for more chemicals and by developing a model for chlorinated solvent transport and transformation.

PRESENTATION	Models as a Component of Decision-Making at Brownfields Sites	07/22/2003

Weaver, J. W. Models as a Component of Decision-Making at Brownfields Sites. Presented at RevTech Conference, Pittsburg, PA, July 22-24, 2003.
Abstract:	Models have become an integral part of decision-making for many LUST and Brownfields sites if only because they form the basis of RCBA tiered assessments. Models, though, are based on a series of assumptions concerning how chemicals behave in the environment, how water flows through the ground, even how a contaminant release occurs. How can you identify these assumptions? We'll present a field guide to models that helps identify model assumptions and their impacts on model results. Data is important, too, and we'll show how the amount and quality of available data affect model results. In practice, inputs to models are selected from various sources, including measurements, literature, defaults, estimates, and calibration. A number of these issues are addressed by a set of on-line calculators that EPA developed for assessment of contaminated sites (www.epa.gov/athens/onsite). We'll look at calculators that can be used to estimate parameters, convert units, and assess uncertainties in calculations. Lastly we'll look at ways to evaluate modeling work. Some steps of evaluation of models can be boiled down to nearly a recipe; also needed are knowledge of fate and transport, modeling in general, and the specific details of the model used.

PRESENTATION	Models as a Component of Decision-Making at Brownfield Sites	07/22/2003

Weaver, J. W. Models as a Component of Decision-Making at Brownfield Sites. Presented at RevTech Conference, Pittsburg, PA, July 22-24, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Prediction of Physicochemical Processes for Environmental Modeling By Computer	09/07/2003

Hilal, S. H. AND L. A. Carreira. Prediction of Physicochemical Processes for Environmental Modeling By Computer. Presented at 226th American Chemical Society National Meeting, New York, NY, September 7-11, 2003.
Abstract:	The major differences among behavioral profiles of molecules in the environment are attributable to their physicochemical properties. For most chemicals, only fragmentary knowledge exists about those properties that determine each compound's environmental fate. A chemical-by-chemical measurement of the required properties is not practical because of expense and because trained technicians and adequate facilities are not available for measurement efforts involving thousands of chemicals. In fact, physical and chemical properties have only been measured for about 1 percent of the approximately 70,000 industrial chemicals listed by the U.S. Environmental Protection Agency's Office of Prevention, Pesticides and Toxic Substances. Hence, the need for physical and chemical constants of chemical compounds has greatly accelerated both in industry and government as assessments are made of potential pollutant exposure and risk. Although a wide variety of approaches are commonly used in regulatory exposure and risk calculations, knowledge of the relevant chemistry of the compound in question is critical to any assessment scenario. For volatilization, sorption and other physical processes, considerable success has been achieved in not only phenomenological process modeling but also a priori estimation of requisite chemical parameters, such as solubilities and Henry's law constants. Granted that considerable progress has been made in process elucidation and modeling for chemical processes such as photolysis and hydrolysis, reliable estimates of the related fundamental thermodynamic and physicochemical properties (i.e., rate and equilibrium constants, distribution coefficient, solubility in water, etc.) have been achieved for only a limited number of molecular structures. The values of these latter parameters, in most instances, must be derived from measurements or from the expert judgment of specialists in that particular area of chemistry. Mathematical models for predicting the transport and fate of pollutants in the environment require reactivity parameter values that is, the physical and chemical constants that govern reactivity. Although empirical structure activity relationships have been developed that allow estimation of some constants, such relationships are generally valid only within limited families of chemicals. A computer program has been under development for more than 12 years that predicts a large number of chemical reactivity parameters and physical properties for a wide range of organic molecules strictly from molecular structure. This prototype computer program called SPARC (SPARC Performs Automated Reasoning in Chemistry) uses computational algorithms based on fundamental chemical structure theory to estimate a variety of reactivity parameters. This capability crosses chemical family boundaries to cover a broad range of organic compounds.

PRESENTATION	Fatty Acid Stable Isotope Indicators of Microbial Carbon Source in Tropical Soils	11/02/2003

Burke Jr., R. A. AND M. Molina. Fatty Acid Stable Isotope Indicators of Microbial Carbon Source in Tropical Soils. Presented at Soil Science Society of America Annual Meeting, Denver, CO, November 2-6, 2003.
Abstract:	The soil microbial community plays an important role in tropical ecosystem functioning because of its importance in the soil organic matter (SOM) cycle. We have measured the stable carbon isotopic ratio (delta13C) of individual phospholipid fatty acids (PLFAs) in a variety of tropical ecosystems that have undergone land use change. In each case the native vegetation, which used the C3 photosynthetic pathway, was replaced with plants that use the C4 photosynthetic pathway (i.e.,sugar cane or pasture grass). Our results imply that delta13C of PLFAs are effective indicators of microbial substrate delta13C in aerobic soils. We further suggest that PLFA delta13C measurements applied to soil chronosequences can be useful indicators of the continued contribution of C3-derived SOM to ecosystem function under the new land use. Our results indicate that the turnover time of C3-derived organic matter varies from about one year to about 50 years in the tropical ecosystems that we have studied.

PRESENTATION	Multiple Imaging Techniques Demonstrate the Manipulation of Surfaces to Reduce Bacterial Contamination	10/13/2003

Arnold, J. W., D. H. Boothe, O. Susuki, AND G. W. Bailey. Multiple Imaging Techniques Demonstrate the Manipulation of Surfaces to Reduce Bacterial Contamination. Presented at First International Meeting on Applied Physics, Badajoz, Spain, October 13-18, 2003.
Abstract:	Surface imaging techniques were combined to determine appropriate manipulation of technologically important surfaces for commercial applications. Stainless steel surfaces were engineered to reduce bacterial contamination, biofilm formation, and corrosion during product processing. The complementarity of microscopy methods, scanning electron microscopy (SEM), electron probe microanalysis, and atomic force microscopy (AFM) with spectrophotometry assessed and correlated form and function of surface modifications. All samples were examined by visual inspection and electron probe microanalysis for surface characteristics and elemental composition, respectively. Natural bacterial populations collected from the processing environment were assessed for their affinity to attach to sample surfaces. Aliquots of bacterial suspensions were diluted in broth and measured by spectrophotometry. Stainless steel disks (1-cm diameter) were added, and the cultures were grown to sufficient density to form monolayers of bacterial cells on control surfaces. The effects of microstructure with changes in manufacture were compared with the phenomena of bacterial interactions at surfaces and material interfaces. The disks for each surface treatment analyzed separately by AFM were cut from the same sheets used for SEM. Disks were examined directly. Relative differences in the surface morphology of stainless steel finishes, including fractal dimensions, Z ranges, roughness, and other measurements corresponded with the differences in reduction of bacterial counts shown by SEM. A model of wet-processing conditions tested the effects of corrosive treatment on bacterial attachment. The effects of rouging, corrosion, and biofouling are costly industrial problems. Bacterial attachment also affected the chemical processes of corrosive treatment at surfaces. The surface resistance achieved by electropolishing reduced bacterial numbers significantly from the other methods tested. In addition, the simplicity of the cleaning process and reduction in chemical use makes it attractive for industrial applications. The design of appropriate materials for the reduction of contamination during food processing necessitates an understanding of the forces of bacterial attachment and corrosion. Final selection of surface finishes is influenced by function and economy.

PRESENTATION	Disinfection By-Products of Emerging Concern: Results of a U.S. Nationwide Occurrence Study	09/22/2003

Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, R. Chinn, M. J. Sclimenti, S. Pastor, H. S. Weinberg, AND G. D. Onstad. Disinfection By-Products of Emerging Concern: Results of a U.S. Nationwide Occurrence Study. Presented at International Workshop Pool Water Chemistry, Drinking Water Disinfection By-Products and Health, Karlsruhe, Germany, September 22-24, 2003.
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. Environmental Protection Agency (EPA) has regulated several DBPs; however, most DBPs have not been tested for adverse health effects due to the high costs involved. In order to prioritize new DBPs for health effects testing, we initiated a U.S. Nationwide Occurrence Study to quantify ?high priority' DBPs (those predicted by toxicology experts to possibly have an adverse health effect) to determine how often they occur and at what levels. The fate and transport of these DBPs in the distribution system was also studied, and new DBPs were identified.Drinking water samples were collected across the United States from 12 plants that use chlorine, ozone, chlorine dioxide, and/or chloramines for disinfection. Locations were chosen to provide waters that contain low and high bromide levels, different pH conditions, and different natural organic matter (NOM) levels. For comparison purposes, regulated and Information Collection Rule DBPs were quantified along with the high priority DBPs. Quantitation methods developed involved various extraction, derivatization, and detection methods (including solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, and purge-and-trap with GC/electron capture detection or GC/MS). For identifying new DBPs, GC with low and high resolution electron ionization-MS and chemical ionization-MS were used. Many of the high priority DBPs were found in drinking waters across the United States. High priority DBPs identified and quantified include 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and brominated forms of MX (the so-called BMXs), iodo-trihalomethanes, other halomethanes, halonitromethanes, haloacids, haloacetaldehydes, haloacetonitriles, haloketones, haloacetates, haloamides, and a few non-halogenated DBPs. Important findings include levels of MX being higher (300-400 ng/L at certain locations) than in previous limited studies. In addition, while the use of alternative disinfectants minimized the formation of the four regulated trihalomethanes, certain DBPs were formed at significant concentrations. For example, iodo-trihalomethanes were highest at a plant that used chloramines only for disinfection; dihaloaldehydes were higher at plants using ozonation and/or chloramination; bromo-trihalonitromethanes were highest at a plant using pre-ozonation (followed by chloramination); and MX and BMX compounds were highest at a plant using chlorine dioxide (followed by chlorination-chloramination). Another important finding was the discovery of iodo-acids. Iodo-acids have never been reported previously for any disinfectant. Five iodo-acids (iodoacetic acid, iodobromoacetic acid, iodobromopropenoic acid (2 isomers), and 2-iodo-3-methylbutenedioic acid) were identified in drinking water from a plant that used chloramine disinfection for high-bromide source waters. Many new brominated haloacids were also identified in drinking waters from several states. Brominated DBPs are important, as current toxicology (and some recent epidemiology) studies suggest that certain brominated DBPs may be of higher health concern than the chlorinated species. Also, preliminary studies with iodoacetic acid show that it is more genotoxic to mammalian cells than brominated DBPs (including bromoacetic acid) and is a developmental toxin in mouse embryos.

PRESENTATION	Disinfection By-Products of Emerging Concern in Drinking Water: Results of a U.S. Nationwide Occurrence Study	09/22/2003

Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, R. Chinn, M. J. Sclimenti, S. J. Pastor, H. S. Weinberg, AND G. D. Onstad. Disinfection By-Products of Emerging Concern in Drinking Water: Results of a U.S. Nationwide Occurrence Study. Presented at International Workshop Pool Water Chemistry, Drinking Water Disinfection By-Products and Health, Karlsruhe, Germany, September 22-24, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	National-Scale Multimedia Risk Assessment for Hazardous Waste Disposal	08/19/2003

Babendreier, J. E. National-Scale Multimedia Risk Assessment for Hazardous Waste Disposal. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Uncertainty and Sensitivity Analyses for Integrated Human Health and Ecological Risk Assessment of Hazardous Waste Disposal	08/13/2003

Babendreier, J. E. Uncertainty and Sensitivity Analyses for Integrated Human Health and Ecological Risk Assessment of Hazardous Waste Disposal. Presented at 2003 Resource Conservation and Recovery Act National Meeting: Putting Resource Conservation into Resource Conservation and Recovery Act, Washington, DC, August 12-15, 2003.
Abstract:	While there is a high potential for exposure of humans and ecosystems to chemicals released from hazardous waste sites, the degree to which this potential is realized is often uncertain. Conceptually divided among parameter, model, and modeler uncertainties imparted during simulation, inaccuracy in model predictions result principally from lack of knowledge and data. In comparison, sensitivity analysis can lead to a better understanding of how models respond to variation in their inputs, which in turn can be used to better focus laboratory and field-based data collection efforts on processes and parameters that contribute most to uncertainty in outputs. Evaluating uncertainty and sensitivity in environmental models can be a difficult task, even for low-order, single-medium constructs driven by a unique set of site-specific data. Quantitative assessment of integrated, multimedia models that simulate hundreds of sites, spanning multiple geographical and ecological regions, will ultimately require a comparative approach using several techniques, coupled with sufficient computational power. Residing within the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES), the Multimedia, Multipathway, and Multireceptor Risk Assessment (3MRA) modeling system is being developed by EPA for use in assessment of hazardous waste management facilities. The 3MRA modelling system includes a set of 17 science modules that collectively simulate release, fate and transport, exposure, and risk associated with hazardous contaminants disposed of in land-based waste management units (WMU). The 3MRA model currently encompasses 922 input variables, over 185 of which are explicitly stochastic. A characteristic of uncertainty analysis (UA) and sensitivity analysis (SA) for very high order models (VHOMs) like 3MRA is their need for significant computational capacity to perform relatively redundant simulations. While UA/SA is emerging as a critical area for environmental model evaluation, Windows-based models have been limited by a lack of supercomputing capacity. Equally, higher-order UA/SA algorithms warrant investigation to determine their efficacy in establishing requisite confidence in the use of VHOMs for regulatory decision-making. Design of SuperMUSE, a 215 GHz PC-based, Windows-based Supercomputer for Model Uncertainty and Sensitivity Evaluation is described. Research is reported for an uncertainty analysis and sensitivity analysis of benzene disposal using 3MRA that describes the relative importance of various exposure pathways in driving risk levels for ecological receptors and human health, evaluating aspects of both site-scale and national scale assessments. Incorporating landfills, waste piles, aerated tanks, surface impoundments, and land application units, the site-based data used in the analysis included 201 national facilities representing 419 site-WMU combinations

PRESENTATION	The Related Role of Environmental Modeling Frameworks	08/19/2003

Laniak, G. F. The Related Role of Environmental Modeling Frameworks. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	In recent years the assessment of environmental systems for the purpose of regulatory decision making has expanded considerably from a medium-specific focus to a comprehensive assessment of contaminant movement from a source, through a multi-media environment (fate and transport), to human and ecological endpoints of concern. The key word with respect to this movement is integration. In the modeling community this means that groundwater modelers, atmospheric modelers, watershed modelers, surface water modelers, ecosystem modelers, and human and ecological exposure and risk modelers must now integrate their knowledge/models to formulate solutions that address all potential impacts. Conceptually, this is a rather straight forward undertaking. Practically, it is wrought with enormous challenges; most notably: 1) the access to, collection of, and organization of the wide array of required input data; 2) the specification of data flow among the science-based models in the system; and 3) the access to modeling tools needed for managing the model interactions, viewing/processing outputs, and assessing uncertainties and sensitivities. The objective of this presentation is to first describe the essential features of modern modeling frameworks, and, secondly, the benefits and challenges associated with integrating our collective framework development efforts in order to develop generic components that are interoperable, that is, components that will operate equally well in all frameworks. A primary conclusion offered in this presentation is the need to encourage developers of uncertainty and sensitivity methods, and models, to develop these tools in a framework independent manner.

PRESENTATION	The Related Role of Environmental Modeling Systems	08/21/2003

Laniak, G. F. The Related Role of Environmental Modeling Systems. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Enantioselective Transformation of Chiral PCBs and the Insecticide Fipronil in Natural Anoxic Sediments	08/24/2003

Jones, W. J., W. L. O'Niell, C. S. Mazur, J. F. Kenneke, AND A. W. Garrison. Enantioselective Transformation of Chiral PCBs and the Insecticide Fipronil in Natural Anoxic Sediments. Presented at 23rd International Symposium on Halogenated Organic Pollutants and Persistent Organic Pollutants, Boston, MA, August 24-29, 2003.
Abstract:	In this study, we examined the microbial transformation of two chiral PCB congeners and the insecticide fipronil in natural sediment microcosms. The specific goals of the study were to identify biotransformation pathways and determine if enantioselective microbial transformation of these chiral compounds occurred under natural environmental conditions.

PRESENTATION	Enantioselective Transformation of Chiral PCBs and Fipronil in Anoxic Sediments	08/26/2003

Jones, W. J., W. L. O'Niell, C. S. Mazur, J. F. Kenneke, AND A. W. Garrison. Enantioselective Transformation of Chiral PCBs and Fipronil in Anoxic Sediments. Presented at 23rd International Symposium on Halogenated Organic Pollutants and Persistent Organic Pollutants, Boston, MA, August 24-29, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Overview of 3mra Technical Approach	08/26/2003

Laniak, G. F. Overview of 3mra Technical Approach. Presented at Science Advisory Board Review, Washington, DC, August 26-27, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Jupiter Project Merging Inverse Problem Formulation Technologies	08/19/2003

Poeter, E., J. E. Babendreier, M. Hill, J. Doherty, AND E. R. Banta. Jupiter Project Merging Inverse Problem Formulation Technologies. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	The JUPITER (Joint Universal Parameter IdenTification and Evaluation of Reliability) project seeks to enhance and build on the technology and momentum behind two of the most popular sensitivity analysis, data assessment, calibration, and uncertainty analysis programs used in environmental applications: PEST (Doherty, 1994, 2002) and UCODE (Poeter and Hill, 1998). These programs are universal in that they can be applied to any computer model; both have very flexible methods for interacting with application models through ASCII files. PEST and UCODE have enjoyed substantial success. Their future, however, depends on their transition into a well-designed, flexible Application Programming Interface (API) that will support new ways of interacting with application models and new, sophisticated capabilities. Much of the technology incorporated in UCODE and PEST has been investigated thoroughly enough that its strengths, weaknesses, and advantageous uses are fairly well known. The frontier of model calibration and associated analysis methods includes pursuits that will benefit from a stable, modularly programmed, full-featured, well-designed, thoroughly documented foundation. JUPITER will provide that foundation for the PEST and UCODE developers, the work of our contemporaries and, we hope, the work of coming generations

PRESENTATION	Uncertainty, Sensitivity, and Parameter Estimation in Risk Assessment Modeling	08/19/2003

Babendreier, J. E. Uncertainty, Sensitivity, and Parameter Estimation in Risk Assessment Modeling. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	An Overview of the Uncertainty Analysis, Sensitivity Analysis, and Parameter Estimation (Ua/Sa/Pe) Api and How to Implement It	08/19/2003

Castleton, K., J. E. Babendreier, S. Fine, E. R. Banta, M. Hill, S. Markstrom, AND G. Leavesley. An Overview of the Uncertainty Analysis, Sensitivity Analysis, and Parameter Estimation (Ua/Sa/Pe) Api and How to Implement It. Presented at International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19-21, 2003.
Abstract:	The Application Programming Interface (API) for Uncertainty Analysis, Sensitivity Analysis, andParameter Estimation (UA/SA/PE API) (also known as Calibration, Optimization and Sensitivity and Uncertainty (CUSO)) was developed in a joint effort between several members of both the Framework Software Workgroup and the Uncertainty and Parameter Estimation Workgroup of the Federal Interagency Steering Committee on Multimedia Environmental Modeling (ISCMEM). The primary purpose for its undertaking, the development of the current draft UA/SA/PE API presented here today attempts to initiate discussion and increase cooperation among the various Federal Agencies in moving towards a common software programming approach for the future development of sharable tools and methods for conducting uncertainty analysis, sensitivity analysis, and parameter estimation.

PRESENTATION	3mra Quality Assurance	08/26/2003

Laniak, G. F. 3mra Quality Assurance. Presented at Science Advisory Board Review, Washington, DC, August 26-27, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Trace Gas and Nutrient Concentrations in Small Streams of the Georgia Piedmont	08/21/2003

Burke Jr., R. A. AND J. Molinero. Trace Gas and Nutrient Concentrations in Small Streams of the Georgia Piedmont. Presented at Invited Seminar at the Joseph W. Jones Ecological Research Center, Newton, GA, August 21, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Modeling Mercury Fate in Various Water Bodies	08/21/2003

Knightes, C. AND R. B. Ambrose Jr. Modeling Mercury Fate in Various Water Bodies. Presented at Combustion Assistance Teleconference Series, Athens, GA, August 21, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Ecological Engineering and Phytoremediation: State of Science and Design	08/28/2003

McCutcheon, S. C. Ecological Engineering and Phytoremediation: State of Science and Design. Presented at Seminar at the University of Alabama, Birmingham, AL, August 28, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Sediment and Contaminant Transport and Fate Modeling Research	08/27/2003

Hayter, E. J. Sediment and Contaminant Transport and Fate Modeling Research. Presented at Superfund Meeting, Cincinnati, OH, August 27, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	3mra Uncertainty and Sensitivity Analysis	08/26/2003

BABENDREIER, J. E. 3mra Uncertainty and Sensitivity Analysis. Presented at Science Advisory Board Review, Washington, DC, August 26 - 27, 2003.
Abstract:	This presentation discusses the Multimedia, Multipathway, Multireceptor Risk Assessment (3MRA) modeling system. The outline of the presentation is: modeling system overview - 3MRA versions; 3MRA version 1.0; national-scale assessment dimensionality; SuperMUSE: windows-based supercomputer; 3MRA ver1.x - UA/SA software tools; model evaluation approaches; 3MRA version 1.0 UA/SA plan; and example model output using version 1.x.

PRESENTATION	Comparison of the Risk Assessment Process for Pesticides and Biopesticides	09/07/2003

Burns, L. A. Comparison of the Risk Assessment Process for Pesticides and Biopesticides. Presented at 226th American Chemical Society National Meeting, New York, NY, September 7-11, 2003.
Abstract:	In the risk assessment process for pesticides, a number of variables are used, including the results obtained from the studies that support registration. Some of these variables are physical and chemical properties of the organisms (crops, growing cycles) and their environments (soils, adjacent surface and ground waters) to be protected. Methods of application, environmental conditions, transport from the site of application, and transformation (degradation) of the applied materials are also considered in assessing populations). Although these assessments are made with data and other available information for conventional pesticides, the comparable information for biopesticides is more sparse. The risk assessment processes for these protective agents are compared.

PRESENTATION	How I Came Into Mass Spectrometry at the U.S. EPA	09/01/2003

Richardson, S. D. How I Came Into Mass Spectrometry at the U.S. EPA. Presented at 16th International Mass Spectrometry Conference, Edinburgh, Scotland, August 31-September 5, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Effect of Ionic Strength on Acid-Base Properties of Vicinal Water	10/15/2003

Galloway, J. R. AND G. W. Bailey. Effect of Ionic Strength on Acid-Base Properties of Vicinal Water. Presented at Annual Biomedical Research Conference for Minority Students, San Diego, CA, October 15-18, 2003.
Abstract:	Surface research over the past 75 years has clearly shown that water under the influence of electrical and magnetic force fields (vicinal water) does not have the same properties as bulk water. Vicinal water is vital in influencing and maintaining the critical spatial and conformational intramolecular relationships in macromolecules. If the structure of the water molecule changes, it may not positively influence the conformation, chemical reactivity, and function of the macromolecule.Our objective was to determine the thermodynamic activity of both innersphere and outersphere water surrounding metal cations. Stock solutions of Li- and CaNO3 were made up having a minimum purity of 99.995%; metal concentrations used were: 9 M, 5.24 M, 3.4 M, 1.9 M, 1.1 M, and 0.6 M. Near-infrared spectroscopy monitored the change in the OH vibrational peaks of the H2O molecule as a function of cation type and ionic strength. The scan range was 4000- 8000 cm-1. For CaNO3 the band at 4400 cm-1 was attributed to innersphere water while the band at 5200 cm-1 is attributed to bulk water. For LiNO3 the O-H band at 7200 cm-1shifted up field, and the absorbency decreases as the metal concentration increases. Ultra-violet spectroscopy and an organic molecular probe were used to measure the Lewis acid-base character of vicinal water. The breaking of the O-H bonds created free protons in the presence of an organic Lewis base, resulting in the formation of a monovalent cation. Solution driven acid-catalyzed hydrolysis was not observed. We conclude that the water activity was lowered due to the elevated salt concentrations, and that proton activity was enhanced. The decrease in activity lowered the strength of the O-H bonds, causing them to have a higher dissociation constant. Three different types of water were observed, innersphere water, outersphere water (water bonded to water), and free water.

PRESENTATION	Modulating Storm Drain Flows to Reduce Stream Pollutant Concentrations	10/28/2003

Frick, W. E. AND D. L. Denton. Modulating Storm Drain Flows to Reduce Stream Pollutant Concentrations. Presented at First Interagency Conference on Research in the Watersheds, Benson, AZ, October 28-30, 2003.
Abstract:	Pathogen and toxic chemical concentrations above the chemical and toxicity water quality standards in creeks and rivers pose risks to human health and aquatic ecosystems. Storm drains discharging into these watercourses often contribute significantly to elevating pollutant concentrations during wet weather, especially following extended periods of dry weather over which pollutants accumulate, or after seasonal pesticides applications that cause high concentrations in retention structures and flood control basins drained by the storm drains. In many instances the discharges from the storm drains are controlled by pumps that run intermittently in response to water level elevations in the retention basins. These pumps usually run at full volume, modulated only in stepwise fashion when more than one pump serves the overflow structure. The on-off mode of operation is insensitive to conditions in the ambient flow or the effluent. Modulating storm drain flows can ameliorate the impact of pathogens or toxic residues found in the storm drain effluent by controlled and optimum mixing of the effluent and ambient streams. Plume models simulating the mixing process in real time based on continuously measured stream levels and storm drain volumes, together with variable flow pumps, could be used to blend the effluent with the receiving stream in a way that mitigates the impact of the storm drain on the environment. The Visual Plumes model is used on a storm drain discharging to urban Arcade Creek in Sacramento, California to demonstrate the potential benefits that may be realized by implementing this strategy.

PRESENTATION	Multi-Aquifer Modeling of Shallow Flow in the Middle Coastal Plain of North Carolina, USA	09/18/2003

Kraemer, S. R. Multi-Aquifer Modeling of Shallow Flow in the Middle Coastal Plain of North Carolina, USA. Presented at MODFLOW 2003: Understanding through Modeling, Golden, CO, September 17-19, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Modeling Nutrient Loads and Response in River and Estuary Systems	10/14/2003

Russo, R. C. Modeling Nutrient Loads and Response in River and Estuary Systems. Presented at North Atlantic Treaty Organization/Committee on the Challenges of Modern Society Plenary Session, Toronto, Canada, October 14, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	The Effects of Different Sample Concentrations on the Structure of Microbial Communities Using Phospholipid Fatty Acid Analysis	11/16/2003

Philip, N. AND M. Molina. The Effects of Different Sample Concentrations on the Structure of Microbial Communities Using Phospholipid Fatty Acid Analysis. Presented at 55th Southeast Regional Meeting of the American Chemical Society, Atlanta, GA, November 16-19, 2003.
Abstract:	Phospholipid fatty acid (PLFA) analysis is a powerful tool for determination of microbial community structures in soils and sediments. However, accurate determination of total microbial biomass and structure of the microbial community may be dependent on the concentration of the soil extracted. In this study we tested the general protocol for PLFA analysis to determine whether different sample concentrations result in a change in PLFA profiles, percent composition of individual PLFAs, and types of PLFAs that can be identified. Samples were obtained from a small stream draining a cattle pasture in the South Fork Broad River watershed in Georgia. Sample concentrations were 1, 5, 10, and 20g of sediment. Total PLFA abundance in the 1g sample was approximately 93 ug/g, while 20g had an abundance of 18ug/g. It was observed however, that a group of fatty acids (18:1w7, cy17:0, 10Me18:0 and 16:1w7) had a general decrease in % composition as the sediment concentration decreased from 20 to 1g. The fatty acid i15:00 had an approximate 70% decrease in total abundance as the sample went from 20 to 1g. It appears from the data that maintaining a sample concentration of 20g is necessary to obtain the most accurate PLFA profiles for microbial structure determination and microbial abundance in sediment samples.

PRESENTATION	Use of Phospholipid Fatty Acid Profiles to Study the Microbial Composition of Cyanobacterial Mats in Cabo Rojo Solar Salterns	10/15/2003

Gonzalez, M. L., L. Casillas, AND M. Molina. Use of Phospholipid Fatty Acid Profiles to Study the Microbial Composition of Cyanobacterial Mats in Cabo Rojo Solar Salterns. Presented at Annual Biomedical Research Conference for Minority Students, San Diego, CA, October 15-18, 2003.
Abstract:	The Cabo Rojo Saltern located in the West side of Puerto Rico is a hypersaline ecosystem that consists of crystallizer ponds surrounded by series of cyanobacterial mats. Although this ecosystem harbors a variety of microorganisms not much is known about their identity and relative abundance. We are particularly interested in how these microbial communities are affected by seasonal changes in the site. To determine the relative abundance of archaeal populations within the ponds and mats of the salterns we have implemented a method to detect archaeal lipids. Two peaks depicting lipids with 23 and 25 carbons and an isoprenoid structure characteristic of archaeabacteria were found in samples collected from the mats during dry and wet seasons. No signals were detected in water samples collected from the ponds, presumably due to low cell yield. We have also generated fatty acids methyl ester (FAME) profiles during the dry and rainy season. The most abundant peaks in the FAME profiles from the microbial mats during the wet season correspond to 18:1 w7c fatty, characteristic of Gram-positive bacteria. We also found iso15:0, common in Gram-positive bacteria, cy19:0 characteristic of anaerobic bacteria, 10me16:0 common among Actinomycetales and some sulfate reducing bacteria, such as Desulfobacter sp, and br 14:0 characteristic of gram positive bacteria. During the dry season, we found basically the same lipids, with the exception of 16:1w7c (a Gram negative indicator) and 18:0 (general indicator). FAME analyses performed on some of the bacterial isolates cultured from the salterns indicated that eleven of our isolates have very little similarity to previously identified bacteria. Our next step is to identify cultured bacteria using phylogenetic analysis to determine whether novel extreme halophiles are common inhabitants of the Cabo Rojo salterns.

PRESENTATION	Environmental Mass Spectrometry: Emerging Contaminants and Current Issues	12/04/2003

Richardson, S. D. Environmental Mass Spectrometry: Emerging Contaminants and Current Issues. Presented at Tandem Mass Spectrometry Workshop, Lake Louise, Canada, December 3-6, 2003.
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 pharmaceuticals, pesticide degradation/reaction products, perfluorooctane sulfonate (PFOS), 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), bromonitromethanes, bromofuranones, iodo-trihalomethanes, and iodo-acids; 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. Analytical chemistry and mass spectrometry measurements/solutions are needed for many of these emerging environmental contaminants. When available, tandem mass spectrometry research that is being applied to these contaminants will also be presented.

PRESENTATION	Predicting the Movement and Bacteria Concentrations of a River Plume in Lake Michigan Using Hydrodynamic Modeling	10/21/2003

Frick, W. E., T. Khangaonkar, R. Whitman, A. P. Dufour, Z. Yang, G. Korinek, AND C. C. West. Predicting the Movement and Bacteria Concentrations of a River Plume in Lake Michigan Using Hydrodynamic Modeling. Presented at State of the Lake 2003 Conference, Muskegon, MI, October 21-22, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Biogeochemical Indicators in Small Piedmont Streams	11/04/2003

Burke Jr., R. A. AND J. Molinero. Biogeochemical Indicators in Small Piedmont Streams. Presented at Scientific Meeting with EPA Region 8, Denver, CO, November 4, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Mtbe Plume Formation: Transport and Modeling Considerations	10/27/2003

Weaver, J. W. Mtbe Plume Formation: Transport and Modeling Considerations. Presented at Interstate Technology Regulatory Commission Meeting, Concord, NH, October 27-28, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Ecological Engineering and Phytoremediation: State of the Science and Design	10/20/2003

McCutcheon, S. C. Ecological Engineering and Phytoremediation: State of the Science and Design. Presented at University of Florida, Gainesville, FL, March 19, 2004.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Swimming Pool Water Disinfection By-Products and Upcoming Research on Iodo-DBPs in Drinking Water	11/06/2003

Richardson, S. D., A. D. Thruston Jr., AND F. G. Crumley. Swimming Pool Water Disinfection By-Products and Upcoming Research on Iodo-DBPs in Drinking Water. Presented at Atlanta-Athens Mass Spectrometry Group Meeting, Athens, GA, November 6, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Modeling to Evolve Understanding of the Shallow Ground Water Flow System Beneath the Lizzie Research Site, Nc	11/15/2003

Kraemer, S. R., T. B. Spruill, A. J. Tesoriero, H. E. Mew Jr., AND K. Farrell. Modeling to Evolve Understanding of the Shallow Ground Water Flow System Beneath the Lizzie Research Site, Nc. Presented at Carolina Geological Society Annual Meeting and Field Trip, Raleigh, NC, November 14-16, 2003.
Abstract:	The purpose of the modeling effort presented here is to evolve a conceptual model of ground-water flow at the Lizzie, NC research site using analytic solutions and field observations. The resulting analytic element parameterization of boundary conditions, aquifer transmissivities, confining layer resistance, and areal recharge distribution will be the foundation for more detailed simulations of water quality, and the potential extrapolation to knowledge of ground-water flow at the watershed scale.

PRESENTATION	Ground Water Mechanics: Basics of the Analytic Element Method	11/15/2003

Bakker, M. AND S. R. Kraemer. Ground Water Mechanics: Basics of the Analytic Element Method. Presented at Carolina Geological Society Annual Meeting and Field Trip, Raleigh, NC, November 14-16, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Good Modeling Practice	11/15/2003

Haitjema, H. M. AND S. R. Kraemer. Good Modeling Practice. Presented at Carolina Geological Society Annual Meeting and Field Trip, Raleigh, NC, November 14-16, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	EPA on-Line Calculators for Ground Water Transport	11/19/2003

Weaver, J. W. EPA on-Line Calculators for Ground Water Transport. Presented at Oconee County High School, Watkinsville, GA, November 19, 2003.
Abstract:	There is no abstract available for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.

PRESENTATION	Jupiter Project Joint Universal Parameter Identification and Evaluation of Reliability	12/08/2003

POETER, E., M. HILL, J. DOHERTY, E. BANTA, AND J. E. BABENDREIER. Jupiter Project Joint Universal Parameter Identification and Evaluation of Reliability. Presented at American Geophysical Union Fall Meeting, San Francisco, CA, December 08 - 12, 2003.
Abstract:	The JUPITER (Joint Universal Parameter IdenTification and Evaluation of Reliability) project builds on the technology of two widely used codes for sensitivity analysis, data assessment, calibration, and uncertainty analysis of environmental models: PEST and UCODE.

PRESENTATION	Enantiomer Fractions of Chlordane Compounds in Sediment Samples from U.S. Geological Survey Sites in Lakes, Rivers, and Reservoirs	08/25/2003

Ulrich, E. M., C. S. Wong, S. A. Rounds, P. C. VanMetre, J. T. Wilson, A. W. Garrison, AND W. T. Foreman. Enantiomer Fractions of Chlordane Compounds in Sediment Samples from U.S. Geological Survey Sites in Lakes, Rivers, and Reservoirs. Presented at Dioxin '03, Boston, MA, August 24-29, 2003.
Abstract:	More than 500 important environmental contaminants are chiral (having structures that are nonsuperimposible mirror images). Although enantiomer pairs have identical physical-chemical properties, their toxicity, biodegradation, and environmental fate often are different. Cyclodextrin gas chromatography combined with mass spectrometry was used to determine the chiral characteristics of chlordane components in sediment. Enantiomer fractions [EF = area (+) enantiomer / sum of (+) and (-) areas] were used to determine if biological degradation had occurred in surficial and suspended-sediment samples, and if there was a trend with depth in sediment cores. Suspended sediment samples showed slight deviation from the racemic EF value of 0.50, suggesting that some biological degradation had occurred prior to sediment deposition in the water body. Surficial sediment samples also contained evidence of biodegradation [cis-chlordane (CC) = 0.492 - 0.620; trans-chlordane (TC) = 0.473 - 0.531; exo-heptachlor epoxide (HEPX) = 0.600 - 0.682]. At five core sites, EFs were close to racemic for TC and CC and in general, TC EFs were less than 0.5 and tend to increase slightly with depth, while the opposite was true for CC. There were no detectable amounts of two chlordane degradation products in sediment core samples. These results suggest that little biodegradation has occurred in the sediment core, and that historical concentration profiles should be unaltered by biological degradation processes. This work has been funded by the US EPA and USGS. It has been subjected to EPA review and approved for presentation. Mention of trade names of commercial products does not constitute endorsement or recommendation for use.

PUBLISHED REPORT	Verification and Validation of the Sparc Model	01/16/2003

Hilal, S. H. Verification and Validation of the Sparc Model. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-03/033 (NTIS PB2004-101168), 2003.
Abstract:	Mathematical models for predicting the transport and fate of pollutants in the environment require reactivity parameter values--that is, the physical and chemical constants that govern reactivity. Although empirical structure-activity relationships that allow estimation of some constants have been available for many years, such relationships generally hold only within very limited families of chemicals. On the other hand, we are developing computer programs that predict chemical reactivity strictly from molecular structure for virtually all organic compounds. Our computer system called SPARC (SPARC Performs Automated Reasoning in Chemistry) uses computational algorithms based on fundamental chemical structure theory to estimate a large array of physical/chemical parameters. This report focuses on the verification and validation of the SPARC Model.

PUBLISHED REPORT	Prediction of Chemical Reactivity Parameters and Physical Properties of Organic Compounds from Molecular Structure Using Sparc	03/19/2003

Hilal, S. H. Prediction of Chemical Reactivity Parameters and Physical Properties of Organic Compounds from Molecular Structure Using Sparc. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-03/030 (NTIS PB2004-101167), 2003.
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 and 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, dipole-dipole, hydrogen bonding, etc.) have been developed using more than 8000 physical property data points on properties such as vapor pressure, boiling point, solubility, Henry's constant, GC retention times, Kow, etc. At the present time, SPARC predicts ionization pKa (in the gas phase and in many organic solvents including water as function of temperature), carboxylic acid ester hydrolysis rate constants (as function of solvent and temperature), E(1/2) reduction potential (as function of solvents, pH and temperature), gas phase electron affinity and numerous physical properties for a broad range of molecular structures.

PUBLISHED REPORT	Working With Whaem2000: Source Water Assessment for a Glacial Outwash Wellfield, Vincennes, Indiana (Revised March 2003)	06/30/2003

Kraemer, S. R., H. M. Haitjema, AND V. A. Kelson. Working With Whaem2000: Source Water Assessment for a Glacial Outwash Wellfield, Vincennes, Indiana (Revised March 2003). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-00/022 (NTIS PB2003-106822), 2003.
Abstract:	The purpose of this document is to introduce the use of the ground water geohydrology computer program WhAEM for Microsoft Windows (32-bit), or WhAEM2000. WhAEM2000 is a public domain, ground-water flow model designed to facilitate capture zone delineation and protection area mapping in support of the state's and tribe's Wellhead Protection Programs (WHPP) and Source Water Assessment Planning (SWAP) for public water well supplies in the United States. Program operation and modeling practice is covered in a series of progressively more complex representations of the wellfield tapping a glacial outwash aquifer for the city of Vincennes, Indiana. WhAEM2000 provides an interactive computer environment for design of protection areas based on radius methods, well in uniform flow solutions, and geohydrologic modeling methods. Protection areas are designed and overlaid upon US Geological Survey Digital Line Graph (DLG) or other electronic base maps. Base maps are available for download from the EPA Center for Exposure Assessment Modeling web site. Geohydrologic modeling for steady pumping wells, including the influence of hydrological boundaries, such as rivers, recharge, no-flow boundaries, and inhomogeneity zones, is accomplished using the analytic element method. Reverse gradient tracelines of known residence time emanating from the pumping center are used to delineate the capture zones. WhAEM2000 has on-line helpand tutorials.

PUBLISHED REPORT	Characteristics of Spilled Oils, Fuels, and Petroleum Products: 1. Composition and Properties of Selected Oils	07/15/2003

Wang, Z., B. P. Hollebone, M. Fingas, B. Fieldhouse, L. Sigouin, M. Landriault, P. Smith, J. Noonan, G. Thouin, AND J. W. Weaver. Characteristics of Spilled Oils, Fuels, and Petroleum Products: 1. Composition and Properties of Selected Oils. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-03/072 (NTIS PB2004-101169), 2003.
Abstract:	Multicomponent composition and corresponding physical properties data of crude oils and petroleum products are needed as input to environmental fate simulations. Complete sets of such data, however, are not available in the literature due to the complexity and expense of making the measurements. Environment Canada has previously developed a database of various physical and chemical properties of crude oils and petroleum products. In this cooperative project, ten "typical" crude oils and refined products in common use or transport were identified for subsequent characterization. Measured oil physical properties include API gravity, density, sulphur content, water content, flash point, pour point, viscosity, surface and interfacial tension, adhesion, the equation for predicting evaporation, emulsion formation, and simulated boiling point distribution. The chemical composition of the oils are quantified for hydrocarbon groups, volatile organic compounds, n-alkane distribution, distribution of alkylatedpolyaromatic hydrocarbon (PAH) homologues and other EPA priority PAHs, and biomarker concentrations. This project will provide the most complete and comprehensive database for the selected oils to date. The new composition data will be integrated into the existing Environment Canada oil properties database. The results will be made available to the public both on the world wide web and as a database on disc.

PUBLISHED REPORT	UV Exposure of Coral Assemblages in the Florida Keys	10/15/2003

Zepp, R. G. UV Exposure of Coral Assemblages in the Florida Keys. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-03/095 (NTIS PB2005-101445), 2003.
Abstract:	Recent studies have indicated that solar radiation can be a significant stressor of coral assemblages in tropical and subtropical marine environments. Here we review the scientific literature related to the interactions of solar radiation with coral reefs, with emphasis on harmful effects of solar UV radiation. Then, we present results of a case study of corals' UV exposure in the Florida Keys. UV exposure was quantified using diffuse attenuation coefficients that were determined using downwelling vertical profiles of UV and visible radiation from sites located at the Upper, Middle and Lower Keys and the Dry Tortugas. For comparison, absorption and fluorescence spectra of the filtered water samples from these sites were measured. Absorption and diffuse attenuation coefficients were highly correlated in the UV-B (290-315 nm) spectral region and ratios of absorption to diffuse attenuation coefficients were > 0.9 throughout this spectral region. Absorption coefficients in the 300 to 500-nm spectral region could be closely described by a nonlinear exponential function. These results indicated that the penetration of solar UV into waters over the coral reefs in the Florida Keys is controlled by the chromophoric component of dissolved organic matter (CDOM) in the water. Analyses of the dependence of underwater UV irradiance on changes in atmospheric ozone or in the UV attenuation coefficients of the water over the reefs indicate that: (1) the dependence on ozone or UV attenuation coefficients can be quantified using radiation amplification factors (RAF); RAFs can be computed using a power relationship for direct UV damage to DNA or for other UV damage to the photosynthetic system of the zooxanthellae associated with corals; (3) UV damage of both types is more sensitive to changes in water UV attenuation coefficients than total ozone, especially damage to the photosynthetic system; (4) RAFs for direct DNA damage to corals caused by changes in ozone are reduced by UV light attenuation in the waters overlying the reefs. Continuous measurements of solar UV-B irradiance (305 nm) at a location close to the reef tract (Sombrero Tower) demonstrated that diffuse attenuation coefficients undergo large diurnal and seasonal variations in response to fluctuating CDOM concentrations that are linked to currents and CDOM transformations. Other results further indicated that light exposure in the waters around the Florida Keys strongly varies with time and location. Generally, diffuse attenuation and absorption coefficients increased sharply along south-to-north transects from the deep bluewaters of the Florida Straits into Hawk Channel, the shallow coastal shelf region between the reef tract and the Keys. The largest change occurred over a narrow region that represented the interface between the green-yellow waters in Hawk Channel and the blue Atlantic water. Analyses of the results obtained at the deep stations just south of the coral reefs also indicated that the depth dependence of both the light and temperature differs greatly between the warm summer months and cold winter months. We found that the upper ocean water close to the coral reefs was generally much more opaque to UV and photosynthetically active radiation (PAR) during the cold winter months than during the summer. During the summer, stratification of the water results in clarification of the waters over the coral reefs and much greater UV and PAR exposure of the reefs. This effect is attributable in part to UV-induced decomposition of the CDOM in the water over the reefs. These results suggest that the extensive stratification which occurs under El Nino conditions may be greatly increasing exposure of the reefs to UV and PAR, thus exacerbating corals bleaching. Other research during the case study indicated that decomposing phytoplankton detritus and decaying litter from seagrasses and mangroves are the major sources of UV-absorbing substances over the coral reefs in the Florida Keys. Management strategies designed to protect seagrasses and mangroves should also play an important role in reducing coral reef exposure to harmful effects of solar radiation.

SUMMARY	Modeling Nutrient Loads and Response in River and Estuary Systems	08/29/2003

Russo, R. C. AND R. Lekevicius. Modeling Nutrient Loads and Response in River and Estuary Systems. U.S. Environmental Protection Agency, Washington, DC, 2003.
Abstract:	This Pilot Study was proposed by the United States and approved at the Committee on the Challenges of Modern Society's (CCMS) plenary session 27-31 March 1999 in Brussels. The proposal was finalized on 12 April 1999. The pilot study intended to address a major and widespread aquatic environmental problem arising from an over-abundance of nutrients (nitrogen, phosphorus) from both point sources, such as municipal sewage, and nonpoint sources, such as agricultural runoff. Excessive nutrient inputs into a water body induce biological, chemical and physical changes in aquatic plant and animal communities, often leading to oxygen depletion. During the Pilot Study, research was conducted to develop additional fundamental scientific knowledge of the effects of nitrogenous pollutants, and to develop and adapt water quality models for nutrients (especially nitrogen), calibrate and test them with field water sampling data, improve and upgrade them, and apply them to specific riverine-estuarine systems, and potentially lake systems, for evaluation and refining. In some cases field sampling and analysis were carried out specifically for the purposes of this study; in others, available data were used. The scientific information and modeling tools will be provided to all interested NATO and EAPC (Euro-Atlantic Partnership Council) countries for their use in application to similar water quality problems in river-estuary systems. The results of this study provide scientific information and predictive models, based on laboratory studies and field sampling and analysis. Such information and modeling tools are important to the development of environmentally protective and economically feasible water quality management activities.

SUMMARY	Identification and Location of Fundamental Fish Assemblages in the Mid-Atlantic Highlands	12/22/2003

Cyterski, M. J. Identification and Location of Fundamental Fish Assemblages in the Mid-Atlantic Highlands. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-05/001, 2003.
Abstract:	To predict fish community response to environmental restoration in the Highlands Region one must first have information on fish abundance and diversity. We used data collected by the US Environmental Protection Agency's EMAP (Environmental Monitoring and Assessment Program) to identify the fundamental fish assemblages of the Mid-Atlantic Highlands Region. EMAP field personnel collected fish from over five hundred Mid-Atlantic streams during 1993-1998. Habitat measurements were taken at many of these sites (e.g., stream flow, dissolved oxygen, temperature, sediment levels, riparian cover) as well as watershed characteristics (e.g., total watershed area, percent area of agriculture, forest, and disturbed land in the watershed). The EMAP survey found that more than two-thirds of streams in the Highlands Region were in fair or poor condition (http://www.epa.gov/maia/html/maha.html) due primarily to sedimentation, habitat loss, deforestation, acid mine drainage, and watershed urbanization.

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