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Ecosystems Research Division Publications: 2004
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This page lists publication titles, citations and abstracts produced by NERL's Ecosystems Research Division for the year 2004, organized by Publication Type. Your search has returned
142 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
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Henry's Law Calculator |
04/15/2004
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Weaver, J. W. Henry's Law Calculator. 2004.
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On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations, and access to methods and data that are not commonly available. Henry's Law Constants characterize the equilibrium distribution of dilute concentrations of volatile, soluble chemicals between gas and liquid. For this calculator, the liquid is water. Temperature-dependence is calculated by two methods: one developed by the EPA Office of Solid Waste and Emergency Response and the other published in the journal Ground Water and written by John Washington in 1996.
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On-Line Calculator: Vapor Intrusion Modeling |
05/04/2004
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Tillman Jr., F. D. AND J. W. Weaver. On-Line Calculator: Vapor Intrusion Modeling. 2004.
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Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion (VI). Volatile organic chemicals in contaminated soils or groundwater can emit vapors, which may migrate through subsurface soils and may enter the indoor air of overlying buildings. Building depressurization may cause these vapors to enter the home through cracks in the foundation. Depressurization can be caused by a combination of wind effects and stack effects, which are the result of heating within the building and/or mechanical ventilation. In extreme cases, the vapors may accumulate in dwellings to levels that may pose near-term safety hazards, such as explosion. Typically, however, vapor concentrations are present at low levels, to which long-term exposure may pose increased risk for chronic health effects. This on-line calculator implements the Johnson and Ettinger (J&E) (Johnson and Ettinger, 1991) simplified model to evaluate the vapor intrusion pathway into buildings. This J&E model replicates the implementation that the US EPA Office of Solid Waste and Emergency Response (OSWER) used in developing its draft vapor intrusion guidance, but includes a number of enhancements that are facilitated by web implementation: temperature dependence of Henry's Law Constants, automatic sensitivity analysis of certain parameters, and others described on the background page. The results you obtain from this OnSite implementation of the Johnson and Ettinger model may differ from other versions of the Johnson & Ettinger Model. In addition to the OSWER implementation that was used for the draft vapor intrusion guidance, EPA Office of Emergency Response and Remediation (OERR) distributes a set of spreadsheet implementations of the model. The differences among these implementations is described in detail on the results page. Beyond these differences the on-line version includes a simplified uncertainty analysis the other implementations lack.
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On-Line Calculator: Forward Calculation Johnson Ettinger Model |
05/26/2004
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Tillman Jr., F. D. AND J. W. Weaver. On-Line Calculator: Forward Calculation Johnson Ettinger Model. 2004.
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On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations, and access to methods and data that are not commonly available. This on-line calculator implements the Johnson and Ettinger (J&E) (Johnson and Ettinger, 1991) simplified model to evaluate the vapor intrusion pathway into buildings. This J&E model replicates the implementation that the US EPA Office of Solid Waste and Emergency Response (OSWER) used in developing its draft vapor intrusion guidance, but includes a number of enhancements that are facilitated by web implementation: temperature dependence of Henry's Law Constants and gaseous diffusivities, automatic sensitivity analysis of certain parameters, and others described on the background page.
The results you obtain from this OnSite implementation of the Johnson and Ettinger model may differ from other versions of the Johnson & Ettinger Model. In addition to the OSWER implementation that was used for the draft vapor intrusion guidance, EPA Office of Emergency Response and Remediation (OERR) distributes a set of spreadsheet implementations of the model. The differences among these implementations is described in detail on the results page. Beyond these differences the on-line version includes a simplified uncertainty analysis the other implementations lack.
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USEPA Example Exit Level Analysis Results |
09/30/2004
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Babendreier, J. E. USEPA Example Exit Level Analysis Results. U.S. Environmental Protection Agency, Washington, DC, 2004.
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Developed by NERL/ERD for the Office of Solid Waste, the enclosed product provides an example uncertainty analysis (UA) and initial process-based sensitivity analysis (SA) of hazardous waste "exit" concentrations for 7 chemicals and metals using the 3MRA Version 1.0 Modeling System. The report was developed for OSW as an interactive, installable electronic report and was crucial to the successful completion of the 2003/2004 SAB review of 3MRA. The electronic form of the report represents a 2 gigabyte hard disk requirement for actual installation on a Windows-based PC. NERL has also made the report available through the web via EPA's Center for Exposure Assessment Modeling (CEAM), located under Multimedia Modeling (http://www.epa.gov/ceampubl/mmedia/3mra/index.htm).
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Biogeochemistry of Mercury in Vermont and New Hampshire Lakes: An Assessment of Mercury in Water, Sediment, and Biota of Vermont and New Hampshire Lakes Comprehensive Final Project Report |
09/30/2004
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Kamman, N., C. T. Driscoll, B. Estabrook, D. Evers, AND E. K. Miller. Biogeochemistry of Mercury in Vermont and New Hampshire Lakes: An Assessment of Mercury in Water, Sediment, and Biota of Vermont and New Hampshire Lakes Comprehensive Final Project Report. U.S. Environmental Protection Agency, Washington, DC, 2004.
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This report summarizes findings of a three-year field study of mercury in freshwater lakes of Vermont and New Hampshire. The study was undertaken jointly by the Vermont Department of Environmental Conservation, New Hampshire Department of Environmental Services, and Syracuse University. The study was designed specifically to determine the generalized level of mercury contamination in sediment, water, and biota of multiple trophic levels across the VT-NH region, using a geographically randomized approach. This type of approach ensures that results provide a statistically valid representation of regionwide conditions. In this summary, average mercury concentrations are provided for several types of measurements, along with the 95% confidence intervals. Results of data analyses are highlighted, and interpretations that carry significant management implications are discussed. Measured values are discussed in light of currently available guidelines or water quality criteria. This study also evaluated the accumulation of Hg in the tissues of lake fish and wildlife.
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Relation of Environmental Characteristics to Fish Assemblages in the Upper French Broad River Basin, North Carolina |
05/01/2004
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Rashleigh, B. Relation of Environmental Characteristics to Fish Assemblages in the Upper French Broad River Basin, North Carolina. ENVIRONMENTAL MONITORING AND ASSESSMENT 93(1-3):139-156, (2004).
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Fish assemblages at 16 sites in the upper French Broad River basin, North Carolina were related to environmental variables using detrended correspondence analysis (DCA) and linear regression. This study was conducted at the landscape scale because regional variables are controlled so that patterns of anthropogenic influence dominate, and because management activities and decisions are most likely to occur at this scale. Environmental variables found most useful for explaining differences among sites were related to agricultural influence; they were agricultural land cover, nitrate-nitrite, sulfate, conductance, and sediment. Agricultural influence on the fish assemblage was represented as a trophic shift from specialized insectivores to one herbivore and generalized insectivores. A secondary influence among sites was related to urban land cover, population density, high concentrations of metals, stream gradient, and soil erodibility. This primarily urban gradient was characterized by an increase in the number of introduced species, sunfish, and other native species. It was shown that the agricultural gradient had a different effect on fish assemblages than the urban gradient. This finding can improve our ability to diagnose impairment in this basin and in similar basins.
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Soil Fluxes of Co2, CO, No and N2o from An Old-Pasture and from Native Savanna in Brazil |
08/05/2004
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Varella, R., M. Bustamante, A. Pinto, K. Kisselle, R. Santos, R. A. Burke Jr., R. G. Zepp, AND L. Viana. Soil Fluxes of Co2, CO, No and N2o from An Old-Pasture and from Native Savanna in Brazil. ECOLOGICAL APPLICATIONS 14(4 Supplement):S221-S231, (2004).
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We compared fluxes of CO2, CO, NO and N2O, soil microbial biomass, and N-mineralization rates in a 20-year old Brachiaria pasture and a native cerrado area (savanna in Central Brazil). In order to assess the spatial variability of CO2 fluxes, we tested the relation between electrical resistivity and soil CO2 emissions. Although the N-mineralization rates in the pasture were low, net N-immobilization was only observed in the dry season. The conversion of the cerrado to pasture decreased the N-inorganic availability and NO fluxes were lower in the pasture than in the cerrado. N2O fluxes were below detection limit at both sites. The CO fluxes showed weak seasonal variation with slightly higher positive fluxes in the dry season and lower fluxes, including net consumption, during the wet season. The cerrado CO fluxes were higher and more variable than the fluxes in the pasture. Both sites showed a seasonal pattern with lower CO2 fluxes (approximately 2 umol CO2m-2s-1) during the dry season. Considering all the wet season, there was not significant differences between the CO2 soil emissions from the cerrado and from the pasture but the temporal trend of the flux differed in the two systems with higher fluxes in the pasture in the transition from wet to the dry season. The electrical resistivity map showed a region of high resistivity on the southeast border of the pasture, and a narrow band of low electrical resistivity oriented east to west on the north side. The existence of the anomalous region of low electrical resistivity, was detected by the technique independently of the season. The low electrical resistivity region showed significantly greater average soil CO2 emissions than the high resistivity region during the wet season. The correlation between soil electrical resistivity and CO2 soil emissions provide evidence that mineralogical variations may exert significant control on CO2 emissions. Moreover, soil electrical resistivity can be used as an efficient tool to determine spatial variability in CO2 emissions.
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Estimation of Carboxylic Acid Ester Hydrolysis Rate Constants |
01/15/2004
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Hilal, S. H., S. W. Karickhoff, L. A. Carreira, AND B. P. Shrestha. Estimation of Carboxylic Acid Ester Hydrolysis Rate Constants. QSAR & COMBINATORIAL SCIENCE 22(9/10):917-925, (2004).
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SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external mechanistic perturbation components. The internal perturbations quantify the interactions of the appended perturber (P) with the reaction center (C). These internal perturbations are factored into SPARC's mechanistic components of electrostatic and resonance effects. External perturbations quantify the solute-solvent interactions and are factored into H-bonding, field stabilization and steric effects. These models have been tested using 1471 measured hydrolysis rate constants in water and mixed-solvent systems at different temperatures. The aggregate RMS deviation of the calculated versus observed values was 0.374 M(-1)s(-1); close to the intralaboratory experimental error.
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Dissolved Organic Fluorophores in Southeastern US Coastal Waters: Correction Method for Eliminating Rayleigh and Raman Scattering Peaks in Excitation-Emission Matrices |
06/15/2004
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Zepp, R. G., W. Sheldon, AND M. A. Moran. Dissolved Organic Fluorophores in Southeastern US Coastal Waters: Correction Method for Eliminating Rayleigh and Raman Scattering Peaks in Excitation-Emission Matrices. MARINE CHEMISTRY 89(1-4):15-36, (2004).
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Fluorescence-based observations provide useful, sensitive information concerning the nature and distribution of colored dissolved organic matter (CDOM) in coastal and freshwater environments. The excitation-emission matrix (EEM) technique has become widely used for evaluating sources and sinks of CDOM. Water scattering peaks, however, can create problems for quantitative analysis and display of the EEMs, especially for samples with low CDOM concentrations. Here we report a new method for eliminating Rayleigh and Raman scatter peaks from EEMs during post-processing of the data in MATLABE.
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Halonitromethane Drinking Water Disinfection By-Products: Chemical Characterization and Mammalian Cell Cytotoxicity and Genotoxicity |
01/01/2004
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Plewa, M. J., E. D. Wagner, P. Jazwierska, S. D. Richardson, P. H. Chen, AND B. McKague. Halonitromethane Drinking Water Disinfection By-Products: Chemical Characterization and Mammalian Cell Cytotoxicity and Genotoxicity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 38(1):62-68, (2004).
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Halonitromethanes are drinking water disinfection by-products that have recently received a high priority for health effects research from the U.S. Environmental Protection Agency. Our purpose was to identify and synthesize where necessary the mixed halonitromethanes and to determine the chronic cytotoxicity and the acute genotoxicity of these agents in mammalian cells. The halonitromethanes included bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromochloronitromethane (DBCNM), bromodichloronitromethane (BDCNM), chloronitromethane (CNM), dichloronitromethane (DCNM) and trichloronitromethane (TCNM). Low and high resolution gas chromatography/mass spectrometry (GC/MS) was used to identify the mixed chloro-bromo-nitromethanes in finished drinking waters and analytical standards that were not commercially available were synthesized (BDCNM, DBCNM, TBNM, CNM, DCNM, BCNM). The rank order of their chronic cytotoxicity (72 h exposure) to Chinese hamster ovary (CHO) cells was DBNM > DBCNM > BNM > TBNM > BDCNM > BCNM > DCNM > CNM > TCNM. The rank order to induce genomic DNA damage in CHO cells was DBNM > BDCNM > TBNM > TCNM > BNM > DBCNM > BCNM > DCNM > CNM. The brominated nitromethanes were more cytotoxic and genotoxic than their chlorinated analogs. This research demonstrated the integration of the procedures for the analytical chemistry and analytical biology when working with limited amounts of sample. The halonitromethanes are potent mammalian cell cytotoxins and genotoxins and may pose a hazard to the public health and the environment.
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Synthesis of Highly Fluorinated Chloroformates and Their Use as Derivatizing Agents for Hydrophilic Compounds and Drinking Water Disinfection By-Products |
02/15/2004
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Vincenti, M., N. Ghiglione, M. C. Valsania, P. Davit, AND S. D. Richardson. Synthesis of Highly Fluorinated Chloroformates and Their Use as Derivatizing Agents for Hydrophilic Compounds and Drinking Water Disinfection By-Products. HELVETICA CHIMICA ACTA 87(2):370-375, (2004).
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A rapid, safe and efficient procedure was developed to synthesize perfluorinated chloroformates in the small scale generally required to perform analytical derivatizations. This new family of derivatizing agents allows straightforward derivatization of highly polar compounds, containing multiple hydroxylic, carboxylic and aminic substituents, directly in the aqueous phase, making them compatible with GC and GC-MS analysis. A goal of this work was to develop a derivatization procedure that would enable the detection and identification of highly polar disinfection byproducts in drinking water.
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Liquid Chromatographic Separation of the Enantiomers of Trans-Chlordane, Cis-Chlordane, Heptachlor, Heptachlor Epoxide and Alpha-Hexachlorocyclohexane With Application to Small-Scale Preparative Separation |
01/23/2004
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Champion Jr., W. L., J. Lee, A. W. Garrison, J. C. DiMarco, A. Matabe, AND K. B. Prickett. Liquid Chromatographic Separation of the Enantiomers of Trans-Chlordane, Cis-Chlordane, Heptachlor, Heptachlor Epoxide and Alpha-Hexachlorocyclohexane With Application to Small-Scale Preparative Separation. JOURNAL OF CHROMATOGRAPHY A 1024(1/2):55-62, (2004).
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Analytical high-performance liquid chromatographic separations of the individual enantiomers of five polychlorinated compounds were obtained on polysaccharide stereoselective HPLC columns. The enantiomers of the pesticides trans-chlordane, cis-chlordane and heptachlor were separated on CHIRALCEL OD using a hexane mobile phase. The enantiomers of the heptachlor metabolite, heptachlor epoxide, were separated on CHIRALPAK AD using a methanol mobile phase. The enantiomers of -hexachlorocyclohexane (-HCH), were separated on CHIRALCEL OJ using a hexane/2-propanol mobile phase. Similar chromatographic conditions using preparative columns were used to isolate approximately 250 mg of each of the individual enantiomers. The purified individual enantiomers have been submitted for testing of their endocrine disruptor (ED) activity.
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Estimation of Microbial Reductive Transformation Rates for Chlorinated Benzenes and Phenols Using a Quantitative Structure-Activity Relationship Approach |
07/15/2004
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TebesStevens, C. L. AND W. J. Jones. Estimation of Microbial Reductive Transformation Rates for Chlorinated Benzenes and Phenols Using a Quantitative Structure-Activity Relationship Approach. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 23(7):1600-1609, (2004).
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A set of literature data was used to derive several quantitative structure-activity relationships (QSARs) to predict the rate constants for the microbial reductive dehalogenation of chlorinated aromatics. Dechlorination rate constants for 25 chloroaromatics were corrected for the effects of hydrophobic partitioning and adjusted for the observed distribution of product species. A number of physicochemical properties and molecular parameters were considered for inclusion in the QSARs. Multivariate statistical analyses were used to select the optimal set of descriptors to minimize multicollinearity between the descriptors, as well as to minimize the p-value of the regression coefficients. The final QSAR included four descriptors: the logarithm of the octanol-water partition coefficient (Kow), the summation of the Hammett sigma constants, and the sigma induction constants in the ortho and meta positions relative to the transformation reaction center. The predictive ability of this QSAR was evaluated using 24 site-specific rate constants that were measured in five separate studies and were not used to derive the expression. The peer-reviewed literature was carefully screened to ensure that all rate constant data was representative of environmentally relevant conditions.
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Book Review of "DRINKING Water Regulation and Health" |
05/15/2004
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Richardson, S. D. Book Review of "DRINKING Water Regulation and Health". JOURNAL OF ENVIRONMENTAL QUALITY 33(3):1162-1163, (2004).
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Since the enactment of the Safe Drinking Water Act (SDWA) in 1974, several amendments and other new regulations have been developed for drinking water. The book, "Drinking Water Regulation and Health", explains these regulations and provides background on why they were developed and how the process works in bringing about a new regulation. This book is a must-read for water utilities, consultants, and regulators. This book also provides useful material for upper-level undergraduates and graduate students in public health or environmental engineering programs.
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Component-Based and Whole-Mixture Techniques for Addressing the Toxicity of Drinking-Water Disinfection By-Product Mixtures |
04/23/2004
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Simmons, J. E., L. K. Teuschler, C. Gennings, T. F. Speth, S. D. Richardson, R. J. Miltner, M. G. Narotsky, K. D. Schenck, E. I. Hunter, R. C. Hertzberg, AND G. Rice. Component-Based and Whole-Mixture Techniques for Addressing the Toxicity of Drinking-Water Disinfection By-Product Mixtures. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 67(8-10):741-754, (2004).
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Chemical disinfection of water is of direct public health benefit as it results in decreased waterborne illness. The chemicals used to disinfect water react with naturally occurring organic matter, bromide and iodide in the source water, resulting in the formation of disinfection byproducts (DBPs). Despite the identification of several hundred DBPs, more than 50% of the mass of total organic halide formed during chlorination remains unidentified. The toxic contribution of the DBPs that are formed and present but not yet chemically identified, the unidentified fraction, has been largely unexplored. A better understanding of the potential for adverse human health consequences associated with exposure to the DBPs present in drinking water will be gained by integration of knowledge on the toxicity of: individual DBPs; simple, defined DBP mixtures; complex, environmentally-realistic DBP mixtures with partial chemical characterization; and, the unidentified fraction.
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Book Review of "CHESAPEAKE Bay Blues: Science, Politics, and the Struggle to Save the Bay" |
07/30/2004
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Burke Jr., R. A. Book Review of "CHESAPEAKE Bay Blues: Science, Politics, and the Struggle to Save the Bay". JOURNAL OF ENVIRONMENTAL QUALITY 33(4):1581, (2004).
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This is a book review of "Chesapeake Bay Blues: Science, Politics, and the Struggle to Save the Bay". This book is very well written and provides an easily understandable description of the political challenges faced by those proposing new or more stringent environmental regulations or programs. This book should be of interest to the general public and to students and professionals in fields such as water quality and ecosystem management, and public policy.
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A Critical Assessment of Elemental Mercury Air/Water Exchange Partners |
11/15/2004
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Loux, N. T. A Critical Assessment of Elemental Mercury Air/Water Exchange Partners. CHEMICAL SPECIATION AND BIOAVAILABILITY. Science and Technology Letters, 16(4):127-138, (2004).
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Although evasion of elemental mercury from aquatic systems can significantly deplete net mercury accumulation resulting from atmospheric deposition, the current ability to model elemental mercury air/water exchange is limited by uncertainties in our understanding of all gaseous air/water exchange phenomena in addition to limitations unique to this element. A critical review of the technical literature is performed; a new estimate for the diffusivity of elemental mercury in water is obtained; a Setschenow coefficient for elemental mercury is published; and a normalized version of the Cole and Caraco (1998) low to intermediate windspeed air/water gaseous exchange model is developed.
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Chromophoric Dissolved Organic Matter (Cdom) Source Characterization in the Louisiana Bight |
06/15/2004
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Chen, R. F., P. Bissett, P. Coble, R. Conmy, G. B. Gardner, M. A. Moran, X. Wang, M. L. Wells, P. Whelan, AND R. G. Zepp. Chromophoric Dissolved Organic Matter (Cdom) Source Characterization in the Louisiana Bight. MARINE CHEMISTRY 89(1-4):257-272, (2004).
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Chromophoric dissolved organic matter (CDOM) in the Mississippi plume region may have several distinct sources: riverine (terrestrial soils), wetland (terrestrial plants), biological production (phytoplankton, zooplankton, microbial), and sediments. Complex mixing, photodegradation, and biological processes make differentiation of the specific sources of CDOM difficult. Using a combination of high resolution in situ observations on an undulating vehicle, the ECOShuttle, a pumping system mounted on the vehicle, and detailed chemical and biological analyses of discrete samples allowed us to characterize two specific sources of CDOM in the Louisiana Bight: the river water constrained in the upper 12 meters of the Mississippi River plume and several subsurface layers of CDOM below the plume. The subsurface CDOM maxima were coincident with steep pycnoclines and sometimes with maxima in chlorophyll a fluorescence. Both sources were actively supplying CDOM to the same location by entirely different processes. The subsurface CDOM was more biologically labile and photochemically refractory than the surface CDOM. Optical properties were also different with relatively higher protein fluorescence and lower spectral slope coefficients in the subsurface CDOM. The geographical extent of the two sources was determined by three-dimensional mapping of the area, and due to the relatively calm conditions in the summer of 2000, thin layers of CDOM produced in the subsurface were observed throughout the region. While riverine inputs dominated the distribution of CDOM in surface waters <12 m in depth, biological production of CDOM, probably due to the bacterial degradation of phytoplankton produced DOM dominated the subsurface waters.
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The Onsite on-Line Calculators and Training for Subsurface Contaminant Transport Site Assessment |
06/15/2004
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Weaver, J. W. The Onsite on-Line Calculators and Training for Subsurface Contaminant Transport Site Assessment. LUSTLINE (June):11-12, (2004).
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EPA has developed a suite of on-line calculators called "OnSite" for assessing transport of environmental contaminants in the subsurface. The purpose of these calculators is to provide methods and data for common calculations used in assessing impacts from subsurface contamination by petroleum hydrocarbons and oxygenated additives. Each calculator contains background information and a guide to their formulas and data. The calculators are available on the Internet at http://www.epa.gov/athens/onsite.
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Environmental Mass Spectrometry: Emerging Contaminants and Current Issues, 2004 Review |
06/15/2004
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RICHARDSON, S. D. Environmental Mass Spectrometry: Emerging Contaminants and Current Issues, 2004 Review. ANALYTICAL CHEMISTRY. American Chemical Society, Washington, DC, 76(12):3337-3364, (2004).
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This review covers developments in environmental mass spectrometry over the period of 2002-2003. A few significant references that appeared between January and March 2004 are also included. This review is in keeping with a current approach of Analytical Chemistry to include only 100-200 significant references and to mainly focus on trends in analytical methods. As a result, this review will limit its focus to new, emerging contaminants and environmental issues that are driving most of the current research. Even with a more narrow focus, only a small fraction of the quality research publications could be discussed. Thus, this review will not be comprehensive, but will highlight new areas and only discuss representative papers in the areas of focus.
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Kinetic Control of Oxidation State at Thermodynamically Buffered Potentials in Subsurface Waters |
12/01/2004
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Washington, J. W., D. M. Endale, L. Samarkina, AND K. E. Chappell. Kinetic Control of Oxidation State at Thermodynamically Buffered Potentials in Subsurface Waters. GEOCHIMICA ET COSMOCHIMICA ACTA. Elsevier Science Ltd, New York, NY, 68(23):4831-4842, (2004).
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Dissolved oxygen (DO) and organic carbon (Corg) are among the highest- and lowest-potential reactants, respectively, of redox couples in natural waters. When DO and Corg are present in subsurface settings, other couples are drawn toward potentials imposed by them, generating a bimodal clustering of calculated redox potentials. Which cluster a couple is drawn toward is determined by whether the couple's oxidant or reductant is more concentrated. Generally, reactants >10-6M are near equilibrium with their dominant complementary reactant and in a cluster, whereas reactants <10-6M react relatively slowly and diverge from the clusters. These observations show that reactions of higher-potential oxidants with lower-potential reductants commonly proceed simultaneously, regardless of the presence of other potential reactants, with the rates of reaction being determined more by concentration than relative potentials. As DO or Corg decreases, the potential gap separating couples diminishes. In waters having quantifiable concentrations of higher potential oxidants O2 and NO3-, [H2] was not diagnostic of their presence. In the water we analyzed having no quantifiable O2 or NO3-, redox potential calculated with [H2] was similar to potentials calculated for SO42- reduction and methanogenesis. Composite reactions, NO3- N2 and O2 H2O, are best characterized in multiple steps due to slow reaction of low-concentration intermediates. The [CO] data we report, among the first for groundwater, are high compared to water equilibrated with the atmosphere.
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| JOURNAL |
Fish Assemblage Groups in the Upper Tennessee River Basin |
12/01/2004
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Rashleigh, B. Fish Assemblage Groups in the Upper Tennessee River Basin. SOUTHEASTERN NATURALIST 3(4):621-636, (2004).
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A hierarchical clustering technique was used to classify sites in the upper Tennessee River basin based on relative abundance of fish species. Five site groups were identified. These groups differed mainly by the occurrence of minnow and darter species. Drainage area and ecoregion were the primary factors explaining the differences among groups; elevation and human influence were of secondary importance. The Blue Ridge site group had the most distinct fish assemblage, large-river sites supported the highest species richness, and the upper Ridge and Valley sites contained the highest percentages of environmentally sensitive species. These results can provide a regional framework for management and conservation activities.
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Modeling Mineral Nitrogen Export from a Forest Terrestrial Ecosystem to Streams |
07/01/2004
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Li, X., R. B. Ambrose Jr., AND R. Araujo. Modeling Mineral Nitrogen Export from a Forest Terrestrial Ecosystem to Streams. TRANSACTIONS OF THE ASAE 47(3):727-739, (2004).
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Terrestrial ecosystems are major sources of N pollution to aquatic ecosystems. Predicting N export to streams is a critical goal of non-point source modeling. This study was conducted to assess the effect of terrestrial N cycling on stream N export using long-term monitoring data from Hubbard Brook Experimental Forest (HBEF) in New Hampshire. The field-scale DAYCENT model was used to quantify N pools and long-term annual streamflow and mineral N export for 6 subwatersheds at the HBEF. By combining DAYCENT with the watershed model the Soil and Water Assessment Tool (SWAT), mineral N export simulations were extended to the watershed scale. Our study indicated that only 13% of external N input was exported to streams during 1951-2000 at HBEF. Most inputted N (4763kg/ha of N) was stored in forest litter, soil organic matter (SOM) and living plant biomass. Net N mineralization of SOM and forest litter contributed 93% of total available N for export within HBEF ecosystem. The Nash-Sutcliffe coefficient evaluating model performance of DAYCENT at 6 subwatersheds ranged from 0.72 to 0.82 for simulating annual streamflow (1964-2000) and from 0.48 to 0.67 for annual mineral N export (1971-1995), indicating reasonable simulated values. DAYCENT successfully predicted the effect of ecosystem disturbance such as forest cut and insect invasion on stream mineral N export. The watershed-scale simulation suggested that soil spatial variability affects stream N export in addition to the accepted controls of land cover, external N input, climate and ecosystem disturbance.
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| JOURNAL |
Photooxidation and Its Effects on the Carboxyl Content of Dissolved Organic Matter in Two Coastal Rivers in the Southeastern United States |
06/24/2004
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Xie, H., O. C. Zafiriou, W. J. Cai, Y. Wang, AND R. G. Zepp. Photooxidation and Its Effects on the Carboxyl Content of Dissolved Organic Matter in Two Coastal Rivers in the Southeastern United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 38(15):4113-4119, (2004).
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Photodecarboxylation (often stoichiometrically expressed as RCOOH + (1/2)O2 (ROH + CO2) has long been postulated to be principally responsible for generating CO2 from photooxidation of dissolved organic matter (DOM). In this study the quantitative relationships were investigated among O2 consumption, CO2 production, and variation of carboxyl content resulting from photooxidation of DOM in natural water samples obtained from the freshwater reaches of the Satilla River and Altamaha River in the Southeastern United States. In terms of loss of dissolved organic carbon (DOC), loss of optical absorbance, and production of CO2, the rate of photooxidation of DOM was increased in the presence of Fe redox chemistry and with increasing O2 content. The ratio of photochemical O2 consumption to CO2 photoproduction ranged from 0.8 to 2.5, depending on the O2 content, the extent of involvement of Fe, and probably the initial oxidation state of DOM as well. The absolute concentration of carboxyl groups ([-COOH]) on DOM only slightly decreased or increased over the course of irradiation, possibly depending on the stages of photooxidation, while the DOC-normalized carboxyl content substantially increased in the presence of Fe redox chemistry and sufficient O2. Both the initial [-COOH] and the apparent loss of this quantity over the course of irradiation was too small to account for the much larger production of CO2, suggesting that carboxyl groups were photochemically regenerated or that the major production pathway for CO2 did not involve photodecarboxylation. The results from this study can be chemically rationalized by a reaction scheme of (a) photodecarboxylation/regeneration of carboxyl: CxHyOz(COOH)m + aO2 + (metals,hv) bCO2 + cH2O2 + Cx-bHy'Oz'(COOH)m-b(COOH)b or of (b) non-decarboxylation photooxidation: CxHyOz(COOH)m + aO2 + (metals,hv) bCO2 + cH2O2 + Cx-bHy'Oz' (COOH)m.
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| JOURNAL |
Comparative Mutagenicity of Halomethanes and Halonitromethanes in Salmonella Ta100: Structure-Activity Analysis and Mutation Spectra. (Erd) |
08/15/2004
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KUNDU, B., S. D. RICHARDSON, C. GRANVILLE, D. T. SHAUGHNESSY, N. M. HANLEY, P. SWARTZ, A. M. RICHARD, AND D. M. DEMARINI. Comparative Mutagenicity of Halomethanes and Halonitromethanes in Salmonella Ta100: Structure-Activity Analysis and Mutation Spectra. (Erd). MUTATION RESEARCH. Elsevier Science Ltd, New York, NY, 554(1-2):335-350, (2004).
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| Abstract:
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Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DPBs) in drinking water that are mutagenic in Salmonella and potent inducers of DNA strand breaks in mammalian cells. Here we compared the mutagenic potencies of the HNMs to those of their halomethane (HM) homologues by testing all nine HNMs and seven of the nine HMs (minus bromomethane and chloromethane) under the same conditions (the pre-incubation assay) in Salmonella TA100 +/- S9. We also determined the mutation spectra for several DBPs. In the presence of S9, all nine HNMs, but only three HMs, dibromomethane (DBM), dichloromethane (DCM), and bromochloromethane (BCM), were mutagenic. Only two DBPs of each class were mutagenic in the absence of S9.
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| JOURNAL |
Role of Seagrass (Thalassia Testudinum) as a Source of Chromophoric Dissolved Organic Matter in Coastal South Florida |
11/16/2004
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Stabenau, E., R. G. Zepp, E. Bartels, AND R. G. Zika. Role of Seagrass (Thalassia Testudinum) as a Source of Chromophoric Dissolved Organic Matter in Coastal South Florida. MARINE ECOLOGY PROGRESS SERIES. Inter-Research, Luhe, Germany, 282:59-72, (2004).
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Seagrasses play a variety of important ecological roles in coastal ecosystems. Here we present evidence that seagrass detritus from the widespread species, Thalassia testudinum, is an important source of ocean color and UV-protective substances in a low latitude coastal shelf region of the United States.
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| JOURNAL |
Mutagenicity in Salmonella of Halonitromethanes: A Recently Recognized Class of Disinfection Byproducts in Drinking Waters. |
08/01/2004
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KUNDU, B., S. D. RICHARDSON, P. D. SWARTZ, P. P. MATTHEWS, A. M. RICHARD, AND D. M. DEMARINI. Mutagenicity in Salmonella of Halonitromethanes: A Recently Recognized Class of Disinfection Byproducts in Drinking Waters. MUTATION RESEARCH. Elsevier Science Ltd, New York, NY, 562(1-2):39-65, (2004).
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| Abstract:
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Halonitromethanes(HNMs)are a recently identified class of disinfection by-products (DBPs) in drinking water.They include chloronitromethane (CHN), dichloronitromethane (DCNM), trichloronitromethane (TCNM), bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromoch-loronitromethane (DBCNM), and bromodichloronitromethane (BDCNM). Here, all nine HNMs were evaluated in the Salmonella plate-incorporation assay +/-S9 using strains TA98, TA100, TA104, TPT100, and the glutathione transferase theta (GSTT1-1)-expressing strain RSJ100. All were mutagenic, most with and without S9. In the absence of S9, six were mutagenic in TA98, six in TA100, and three in TA104; in the presence of S9, these numbers were five, seven, and three, respectively.
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| JOURNAL |
Chemical and Biological Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts |
09/01/2004
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Plewa, M. J., E. D. Wagner, S. D. Richardson, A. D. Thruston Jr., Y. T. Woo, AND B. McKague. Chemical and Biological Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 38(18):4713-4722, (2004).
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Iodoacid drinking water disinfection byproducts (DBPs) were recently uncovered in drinking water samples from source water with a high bromide/iodide concentration that was disinfected with chloramines. The purpose of this paper is to report the analytical chemical identification of iodoacetic acid (IA) and other iodoacids in drinking water samples, to address the cytotoxicity and genotoxicity of IA in Salmonella typhimuriumand mammalian cells, and to report a structure-function analysis of IA with its chlorinated and brominated monohalogenated analogues. The iodoacid DBPs were identified as iodoacetic acid, bromoiodoacetic acid, ( Z)- and ( E)-3-bromo-3-iodopropenoic acid, and ( E) -2-iodo-3-methylbutenedioic acid. IA represents a new class (iodoacid DBPs) of highly toxic drinking water contaminants. The cytotoxicity of IA in S. typhimurium was 2.9x and 53.5x higher than bromoacetic acid (BA) and chloroacetic acid (CA), respectively. A similar trend was found with cytotoxicity in Chinese hamster ovary (CHO) cells; IA was 3.2x and 287.5x more potent than BA and CA, respectively. This rank order was also expressed in its genotoxicity with IA being 2.6x and 523.3x more mutagenic in S. typhimuriumstrain TA100 than BA and CA, respectively. IA was 2.0_x more genotoxic than BA and 47.2x more genotoxic than CA in CHO cells. The rank order of the toxicity of these monohalogenated acetic acids is correlated with the electrophilic reactivity of the DBPs. IA is the most toxic and genotoxic DBP in mammalian cells reported in the literature. These data suggest that chloraminated drinking waters that have high bromide and iodide source waters may contain these iodoacids and most likely other iodo-DBPs. Ultimately, it will be important to know the levels at which these iodoacids occur in drinking water in order to assess the potential for adverse environmental and human health risks.
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| JOURNAL |
Prediction of the Solubility, Activity Coefficient and Liquid/Liquid Partition Coefficient of Organic Compounds |
11/15/2004
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Hilal, S. H., S. W. Karickhoff, AND L. A. Carreira. Prediction of the Solubility, Activity Coefficient and Liquid/Liquid Partition Coefficient of Organic Compounds. QSAR & COMBINATORIAL SCIENCE 23(9):709-720, (2004).
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| Abstract:
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Solvation models, based on fundamental chemical structure theory, were developed in the SPARC mechanistic tool box to predict a large array of physical properties of organic compounds in water and in non-aqueous solvents strictly from molecular structure. The SPARC self-interaction solvation models that describe the intermolecular interaction between like molecules (solute-solute or solvent-solvent) were extended to quantify solute-solvent interaction energy in order to estimate the activity coefficient in almost any solvent. Solvation models that include dispersion, induction, dipole-dipole and hydrogen bonding interactions are used to describe the intermolecular interaction upon placing an organic solute molecule in any single or mixed solvent system. In addition to estimation of the activity coefficient for 2604 organic compounds, these solvation models were validated on solubility and liquid/liquid distribution coefficient in more than 163 solvents including water. The RMS deviations of the calculated versus observed activity coefficients, solubilities and liquid/liquid distribution coefficients were 0.272 log mole fraction, 0.487 log mole fraction and 0.44 log units, respectively.
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| JOURNAL |
Visual Plumes Mixing Zone Modeling Software |
08/01/2004
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Frick, W. E. Visual Plumes Mixing Zone Modeling Software. ENVIRONMENTAL MODELLING AND SOFTWARE 19(7-8):645-654, (2004).
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| Abstract:
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The US Environmental Protection Agency has a history of developing plume models and providing technical assistance. The Visual Plumes model (VP) is a recent addition to the public-domain models available on the EPA Center for Exposure Assessment Modeling (CEAM) web page. The Windows-based VP adapts, modifies, and enhances the earlier DOS-based PLUMES with a new interface, models, and capabilities. VP is a public platform for mixing zone models designed to encourage the continued improvement of plume theory and models by facilitating verification and inter-model comparison. Some examples are presented to illustrate VP's new capabilities. One demonstrates its ability, for reasonably one-dimensional estuaries, to estimate background concentrations due to tidal re-circulation of previously contaminated receiving water. This capability depends on the optional linkage to time-series input files that enables VP to simulate mixing zone and far-field parameters for long periods. Also described are the new bacterial decay models used to estimate depth changes in first-order decay rates based on environmental stressors, including solar insolation, salinity, and temperature. The nascent density phenomenon is briefly described as it is potentially important to Outer Continental Shelf (OCS) oil exploration discharges
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| JOURNAL |
Environmental Effects of Ozone Depletion and Its Interactions With Climate Change: Progress Report 2003 |
01/20/2004
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ZEPP, R. G., T. V. CALLAGHAN, AND D. ERICKSON. Environmental Effects of Ozone Depletion and Its Interactions With Climate Change: Progress Report 2003. PHOTOCHEMICAL AND PHOTOBIOLOGICAL SCIENCES 3(1):1-5, (2004).
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| Abstract:
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The measures needed for the protection of the Earth's ozone layer are decided regularly by the Parties to the Montreal Protocol. A section of this progress report focuses on the interactive effects of climate change and ozone depletion on biogeochemical cycles.
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| NON-EPA PUBLISHED PROCEEDINGS |
Proceedings of the International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling. EPA/600/R-04/117, Nureg/Cp-0187, Erdc Sr-04-2. |
10/01/2004
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NICHOLSON, T. J., J. E. BABENDREIER, P. D. MEYER, S. MOHANTY, B. B. HICKS, AND G. H. LEAVESLEY. Proceedings of the International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling. EPA/600/R-04/117, Nureg/Cp-0187, Erdc Sr-04-2. International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19 - 21, 2003. U.S. Nuclear Regulatory Commission, Washington, DC 258 pgs., (2004).
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| Abstract:
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An International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling was held August 1921, 2003, at the U.S. Nuclear Regulatory Commission Headquarters in Rockville, Maryland, USA. The workshop was organized and convened by the Federal Working Group on Uncertainty and Parameter Estimation, and sponsored by the Federal Interagency Steering Committee on Multimedia Environmental Models (ISCMEM). The workshop themes were parameter estimation, sensitivity analysis, and uncertainty analysis relevant to environmental modeling. The workshop objectives were to facilitate communication among U.S. Federal agencies conducting research on the workshop themes; obtain up-to-date information from invited technical experts; actively discuss the state-of-the-science in the workshop themes; and identify opportunities for pursuing new approaches. The invited presenters focused on methods to identify, evaluate, and compare both existing and newly developed strategies and tools for parameter estimation, sensitivity and uncertainty analyses. Discussions explored how these strategies and tools could be used to better understand and characterize the sources of uncertainty in environmental modeling, and approaches to quantify them through comparative analysis of model simulations and monitoring.
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| PAPER IN NON-EPA PROCEEDINGS |
Calibration, Optimization, and Sensitivity and Uncertainty Algorithms Application Programming Interface (Cosu-Api) |
10/01/2004
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Babendreier, J. E. Calibration, Optimization, and Sensitivity and Uncertainty Algorithms Application Programming Interface (Cosu-Api). In Proceedings, International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19 - 21, 2003. U.S. Nuclear Regulatory Commission, Washington, DC, A1-A54, (2004).
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| Abstract:
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The Application Programming Interface (API) for Uncertainty Analysis, Sensitivity Analysis, and Parameter Estimation (UA/SA/PE API) tool development, here fore referred to as the Calibration, Optimization, and Sensitivity and Uncertainty Algorithms API (COSU-API), was initially 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 draft COSU-API (Version: June, 2003), presented formally in this document, 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. Overview elements of the COSU-API were initially presented and discussed among participants attending the August 2003 ISCMEM International Workshop on Uncertainty Analysis, Sensitivity Analysis, and Parameter Estimation.
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| PAPER IN NON-EPA PROCEEDINGS |
A Perspective from U.S. EPA: Uncertainty, Sensitivity, and Parameter Estimation in Multimedia Exposure and Risk Assessment Modeling |
10/01/2004
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Babendreier, J. E. A Perspective from U.S. EPA: Uncertainty, Sensitivity, and Parameter Estimation in Multimedia Exposure and Risk Assessment Modeling. In Proceedings, International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19 - 21, 2003. U.S. Nuclear Regulatory Commission, Washington, DC, 13-17, (2004).
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| Abstract:
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Since its amalgamation as a Federal Agency over 30 years ago, the U.S. Environmental Protection Agency (EPA) has undertaken many activities contributing to the international community's collective foundation for modern, multimedia environmental modeling. A key component of its current research agenda, the Agency is seeking to better understand the role and functionality of multimedia modeling as an exposure/risk assessment tool to support sound decision-making. Complimenting data collection, also a fundamental activity supporting its mission, EPA's complementary modeling efforts were initially focused on single-medium paradigms, which have formed, for the most part, the technical basis of many of today's regulatory programs. Over the last decade, EPA's assessment capabilities have matured into several integrated, multimedia-modeling software technologies that currently sit at or near deployment for use by both regulators and stakeholders. As these more complex, integrated assessment tools become engaged in the decision-making process, their use has underscored the need to more transparently characterize the attendant uncertainty in model inputs and outputs, and the associated sensitivity of model outputs to input error. Understanding, communicating, and optimally managing the strengths and weaknesses of integrated science, quantitatively captured as multimedia modeling technologies and data, is clearly one of the Agency's greatest goals and challenges. Discussion presented here on EPA's research perspectives for multimedia environmental modeling focus on several themes: modern environmental assessments; probabilistic exposure/risk assessments; OMB-driven information quality guidelines; example research activities being conducted at USEPA/ORD/NERL.
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| PAPER IN NON-EPA PROCEEDINGS |
Toward Development of a Common Software Application Programming Interface (Api) for Uncertainty, Sensitivity, and Parameter Estimation Methods and Tools |
10/01/2004
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Babendreier, J. E. Toward Development of a Common Software Application Programming Interface (Api) for Uncertainty, Sensitivity, and Parameter Estimation Methods and Tools. In Proceedings, Proceedings of the International Workshop on Uncertainty, Sensitivity, and Parameter Estimation for Multimedia Environmental Modeling, Rockville, MD, August 19 - 21, 2003. U.S. Nuclear Regulatory Commission, Washington, DC, 153-169, (2004).
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| Abstract:
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The final session of the workshop considered the subject of software technology and how it might be better constructed to support those who develop, evaluate, and apply multimedia environmental models. Two invited presentations were featured along with an extended open discussion on the concept of creating a core "interface level" of programming standards for environmental modeling software. Discussion was primarily devoted to review of a recently developed experimental Application Programming Interface (API) for uncertainty analysis (UA), sensitivity analysis (SA), and parameter estimation (PE) methods and tools. Designated as the Calibration, Optimization, and Sensitivity and Uncertainty Algorithms API (CUSO-API; Appendix A), the API was created through a joint collaboration of ISCMEM's Software System Design and Implementation Workgroup and the Uncertainty Analysis and Parameter Estimation Workgroup. The goal of this session was to begin building towards consensus on an adoptable UA/SA/PE API that might one day evolve to meet most, if not all, of the related UA/SA/PE needs of environmental modelers.
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| PRESENTATION |
Louisiana Environmental Modeling System for Hypoxia Related Issues |
06/15/2004
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Carousel, R. F. AND R. C. Russo. Louisiana Environmental Modeling System for Hypoxia Related Issues.
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| Abstract:
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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.
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| PRESENTATION |
An Exact Method for Relating Zwitterionic Microscopic to Macroscopic Acidity Constants |
03/29/2004
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Loux, N. T. An Exact Method for Relating Zwitterionic Microscopic to Macroscopic Acidity Constants. Presented at 227th American Chemical Society National Meeting, Anaheim, CA, March 28-April 1, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Variations in the Spectral Properties of Estuarine Water Caused By Cdom Partitioning Onto River and Estuarine Sediments |
02/15/2004
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SHANK, G. C., R. G. ZEPP, R. F. WHITEHEAD, AND M. L. SMITH. Variations in the Spectral Properties of Estuarine Water Caused By Cdom Partitioning Onto River and Estuarine Sediments. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15 - 20, 2004.
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We investigated the impact of CDOM partitioning onto natural and model sediments on the UV and visible spectral properties of two southeastern U.S. river systems (Satilla and Cape Fear).
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| PRESENTATION |
Dynamic Tuning of Insect and Bird Wings and Copepod and Daphnia Appendages |
02/15/2004
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Frick, W. E., D. L. Denton, AND M. C. Barber. Dynamic Tuning of Insect and Bird Wings and Copepod and Daphnia Appendages. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15-20, 2004.
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| Abstract:
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Compressible flow theory suggests, and dimensional analysis and growing empirical evidence confirm that, to aid flight, many insects and even some birds, notably hummingbirds, tune their wing-beat frequency to a corresponding characteristic harmonic frequency of air. The same property that governs the physics of acoustics, the compressibility of air and water, helps insects to fly and small aquatic animals to swim and capture food. The basic principle is simple, all the animal has to do, for example, to hover, is to beat its wings at exactly half the natural compressive frequency of air, or water. To use insect flight to help understand the principle, if at the tuned frequency the insect achieves maximum compression below the wing at mid downstroke, then the elastic properties of air will achieve maximum recoil decompression at the bottom of the stroke followed by maximum compression on the subsequent up stroke. The opposite is true above the wings. Albeit not as great as on the downstroke, the animal gets a free boost on the upstroke. The phenomenological governing variables are identified and the wing-beat frequency is derived from dimenstional analysis and physical reasoning.
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| PRESENTATION |
Dynamic Tuning of Copepod and Daphnia Appendages |
02/16/2004
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Denton, D. L., W. E. Frick, AND M. C. Barber. Dynamic Tuning of Copepod and Daphnia Appendages. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15-20, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Using Public-Domain Models to Estimate Beach Bacteria Concentrations |
02/15/2004
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Frick, W. E., D. J. Baumgartner, M. Molina, T. Khangaonkar, AND G. L. Robertson. Using Public-Domain Models to Estimate Beach Bacteria Concentrations. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15-20, 2004.
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| Abstract:
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Stretches of beach along popular Huntington Beach, California are occassionally closed to swimming due to high levels of bacteria. One hypothesized source is the treated wastewater plume from the Orange County Sanitation District's (OCSD) ocean outfall. While three independent science review panels found no strong or consistent links between the ocean discharge four miles offshore and bacteria concentrations in the surf zone, the empirical data provided only intermittent evidence of the offshore plume, making it impossible to disprove the hypothesis. Computer models could have filled the data gaps with simulated concentrations, using monitoring data to verify the models. A public-domain model to address the problem is under development. Called Visual Beach, in concept it is patterned after the USEPA Visual Plumes program, using its initial dilution models to estimate plume rise and dilution and its built-in bacteria decay models to estimate concentrations. However, it is being modified to use the Environmental Fluid Dynamics Code (EFDC) to estimate long-term waste-field movement. Using time-series records of effluent flow and characteristics, ocean currents, and density stratification, continuous estimates of waste-field location are achieved.
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| PRESENTATION |
Consequences of Non-Linear Density Effects on Buoyancy and Plume Behavior |
02/20/2004
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Frick, W. E. AND D. J. Baumgartner. Consequences of Non-Linear Density Effects on Buoyancy and Plume Behavior. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15-20, 2004.
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| Abstract:
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Aquatic plumes, as turbulent streams, grow by entraining ambient water. Buoyant plumes rise and dense ones sink, but, non-linear kinetic effects can reverse the buoyant force in mid-phenomenon. The class of nascent-density plumes begin as buoyant, upwardly accelerating plumes that subsequently reverse buoyancy, sinking to a more submerged trapping level or the bottom. Unlike double diffusion, where density adjusts to radiative or conductive temperature changes and salinity, the nascent-density effect is due to the mixing of plume and ambient fluids. A nascent-density example is a freshwater thermal plume discharged to freezing ambient fresh water, or to freezing brackish water up to a salinity of about 14psu. The highly buoyant plume rapidly becomes denser than the ambient fluid as the plume element temperature cools by entrainment. Once the mixture temperature falls below about 8C it becomes denser than the surrounding freezing water, decelerating its acquired upward velocity and ultimately sinking. If the equation of state were linear it would rise to an elevated trapping level or to the surface. The USEPA Visual Plumes software illustrates pertinent concepts with comparative examples.
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| PRESENTATION |
Non-Linear Density Effects on Buoyance and Plume Behavior |
02/20/2004
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Frick, W. E. AND D. J. Baumgartner. Non-Linear Density Effects on Buoyance and Plume Behavior. Presented at 2004 Ocean Research Conference, Honolulu, HI, February 15-20, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Effect of Management Practices on the Soil Microbial Community in Agricultural and Native Systems in Brazil |
05/24/2004
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Molina, M., L. Viana, R. A. Burke Jr., M. Bustamante, AND R. G. Zepp. Effect of Management Practices on the Soil Microbial Community in Agricultural and Native Systems in Brazil. Presented at American Society for Microbiology Annual Meeting, New Orleans, LA, May 23-27, 2004.
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| Abstract:
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Increase in agricultural practices in the Cerrado (tropical savannah) and Amazon regions in Brazil is causing drastic changes in the nutrient and carbon cycling of native areas. Because microorganisms play a key role in biogeochemical cycling, monitoring the shifts in the microbial community structure may provide information about the nutrient and carbon dynamics in these ecosystems. We compared microbial communities under a range of management practices which included different native areas (savannah and forest), a pasture site, and a Cerrado area subjected to fertilization treatments (N, P, N+P, Ca) using phospholipid fatty acid analysis (PLFAs) and fungal to bacterial ratios. Fertilizers were applied after 10, 20 and 40 days to four plots (15 x15m) per treatment in a completely randomized design. Although the total PLFA concentration did not show significant differences among the sites, principal component analysis indicated that the structure of the microbial community varied as a function of the fertilization treatment and management practice (p<0.0001). In the fertilization experiment, Ca and the control treatment exhibited basically the same community structure and had a higher concentration of Gram negative biomarkers, while N, P, and N+P treatments had a higher concentration of Gram positive biomarkers and similar microbial communities. P amendments produced a higher fungal:bacterial ratio after 10 days of fertilization and was the only treatment showing a significant difference in the ratios. Fungal:bacterial ratios were also significantly higher in the pasture site when compared to the ratios observed in the native savannah and Amazon soils. The higher ratio in the pasture site correlated with lower availability of nitrogen and was a function of a decrease in the % composition of bacterial PLFAs. The fungal biomarker (18:2w6) maintained the same % composition across sites. The results suggest a phosphorus limitation on the fungal community inhabiting native Cerrado soils, while in pastures, nitrogen seems to limit the bacterial community, but has no effect on the fungi. Addition of N and P shifts the microbial community, increasing the concentration of Gram positive bacteria.
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| PRESENTATION |
Development and Validation of a Mechanistic Ground Sprayer Model |
08/01/2004
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Teske, M. E., N. J. Ewing, N. B. Birchfield, AND S. L. Bird. Development and Validation of a Mechanistic Ground Sprayer Model. Presented at 2004 American Society of Agricultural Engineers/Canadian Society of Agricultural Engineering International Meeting, Ottawa, Canada, August 1-4, 2004.
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| Abstract:
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In the last ten years the Spray Drift Task Force (SDTF), U.S. Environmental Protection Agency (EPA), USDA Agricultural Research Service, and USDA Forest Service cooperated in the refinement and evaluation of a mechanistically-based aerial spray model (contained within AGDISP and AgDRIFT). This model was validated with an extensive set of aerial field trials conducted by the SDTF, and is now used by the EPA for pesticide risk assessments. Building on previous work, the authors have developed a companion model for ground-based pesticide applications that extends the capabilities of the empirical ground sprayer model contained in AgDRIFT. Because the AgDRIFT ground sprayer model is empirically based on a data set with a limited range of ground sprayer operational conditions, current AgDRIFT ground sprayer predictions are limited to estimating downwind deposition from one of four application scenarios (two release heights and two atomization spectra). With the development of a new mechanistic ground sprayer model, users will have more flexibility in selecting release height, nozzle type, tank mix properties, crosswind, temperature and relative humidity, number of swaths, etc. This paper will present the algorithms of the complete mechanistic model, and compare model predictions with downwind deposition measurements from previously conducted ground sprayer field studies.
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| PRESENTATION |
Modeling Plumes in Small Streams |
03/29/2004
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Frick, W. E., D. L. Denton, AND K. P. George. Modeling Plumes in Small Streams. Presented at 227th American Chemical Society National Meeting, Anaheim, CA, March 28-April 1, 2004.
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| Abstract:
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Pesticides accumulate on land surfaces from agricultural, commercial, and domestic application, and wash into streams and rivers during dry and wet weather. Flood water retention basins or structures often collect this contaminated runoff, providing intermediate storage and limiting the effluent to one or more storm drains. When storm drains are flowing, the outfall terminals, or ports, form plumes in the receiving stream. Depending on effluent and receiving water flows, effluent and ambient pesticide concentrations, and other variables, such as chemical decomposition, the plumes can form regions of limited impact or overwhelm ambient conditions and lead to extensive downstream degradation. In some cases modifying the conditions of discharge, for example, reducing pump flow rates, will reduce downstream plume concentrations. The EPA Visual Plumes model is used to illustrate the use of models to predict in-stream plume concentrations, trajectories, and cross-sectional distributions of pesticides. A small urban creek in California, is used to simulate a storm drain site. Another example shows the model applied to a very shallow stream in Alaska. The model helps to understand the relationship between effluent and ambient flows and suggests ways to limit harmful concentrations of pesticides in small streams.
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| PRESENTATION |
Evaluation of Chemical Bioaccumulation Models |
01/07/2004
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Hayter, E. J. Evaluation of Chemical Bioaccumulation Models. Presented at Office of Science Policy/Office of Superfund Remediation and Technology Innovation Contaminated Sediments Seminar Series, Washington, DC, January 7, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Internet Course on Modeling Subsurface Transport of Petroleum Hydrocarbons |
03/01/2004
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Weaver, J. W. Internet Course on Modeling Subsurface Transport of Petroleum Hydrocarbons. Presented at 16th National Underground Storage Tank Conference, New Orleans, LA, March 1-3, 2004.
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| Abstract:
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Assessment of leaks from underground storage tanks relies on knowledge of contaminant fate and transport, hydrology and in some cases modeling. EPA is developing an interactive, on-line training course to provide states with a low-cost training opportunity for these areas. Two of a planned total of about 20 modules have been completed and are available for use on the EPA web site at http://www.epa.gov/athens/learn2model. The first gives an introduction to the course and illustrates the contaminant fate and transport with examples from field sites. The second uses two sets of flow visualization experiments to illustrate multiphase fluid distribution in the pore space. The next modules to be added will cover ground water flow, contaminant retardation, dispersion and biodegradation. Each module contains an introduction, set of objectives, twenty to thirty web pages, and a quiz. Interactive features are included through use of the EPA OnSite on-line calculators, that are available separately for use at http://www.epa.gov/athens/onsite. When a score of 85% or higher is achieved a certificate can be printed as a record of completion. The course is available free-of-charge to anyone and is expected to be useful for regulators and consultants alike.
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| PRESENTATION |
Statistical Techniques for Determination and Prediction of Fundamental Fish Assemblages of the Mid-Atlantic Highlands |
05/03/2004
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Cyterski, M. J., M. C. Barber, R. S. Parmar, B. Rashleigh, AND K. Wolfe. Statistical Techniques for Determination and Prediction of Fundamental Fish Assemblages of the Mid-Atlantic Highlands. Presented at Environmental Monitoring and Assessment Program Symposium 2004, Newport, RI, May 3-7, 2004.
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| Abstract:
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A statistical software tool, Stream Fish Community Predictor (SFCP), based on EMAP stream sampling in the mid-Atlantic Highlands, was developed to predict stream fish communities using stream and watershed characteristics. Step one in the tool development was a cluster analysis that characterized observed fish communities to form groups of streams with similar fish species. Twenty-three clusters, each defined by a fundamental fish assemblage, resulted. Step two was a discriminant analysis, which produced a system of equations to predict a stream's fundamental fish assemblage (its cluster) based on characteristics of that stream and its watershed (e.g., stream slope, percent forested area in the watershed, stream bank vegetation, latitude, longitude). The discriminant equations, when tested using our sample data, correctly predicted a stream's fish assemblage with approximately 35% accuracy. If the user examined the three most probable assemblages for a stream, the accuracy rose to approximately 65% (i.e., 65% of the time one of those three choices was the correct assemblage). Randomly, given three choices, one would only have a 3 in 23 chance of picking the correct assemblage (13%). The tool will be used to predict fish communities in streams for which basic watershed and stream characteristics are known. This software also allows users to investigate potential impacts of environmental restoration or degradation by altering stream and watershed characteristics, then examining changes in the predicted fish community. This tool is currently available from the Canaan Valley Institute's website at http://www.canaanvi.org/.
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| PRESENTATION |
Determination and Prediction of Fundamental Fish Assemblages in the Mid-Atlantic Highlands |
05/04/2004
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Cyterski, M. J., M. C. Barber, R. S. Parmar, B. Rashleigh, AND K. Wolfe. Determination and Prediction of Fundamental Fish Assemblages in the Mid-Atlantic Highlands. Presented at Environmental Monitoring and Assessment Program Symposium 2004, Newport, RI, May 3-7, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Biogeochemical Indicators of Organic Waste Contamination in Small Streams of the Georgia Piedmont |
05/03/2004
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Burke Jr., R. A. AND J. Molinero. Biogeochemical Indicators of Organic Waste Contamination in Small Streams of the Georgia Piedmont. Presented at Environmental Monitoring and Assessment Program Symposium 2004, Newport, RI, May 3-7, 2004.
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We monitored concentrations of nitrous oxide, methane, carbon dioxide, nutrients and other parameters (T, conductivity, dissolved oxygen, alkalinity, pH, DOC, DON, flow rate) in 17 headwater streams (watershed sizes from 0.5 to 3.4 km2) of the South Fork Broad River, Georgia watershed on a monthly basis for a year. We also measured the stable nitrogen isotope ratio of plants growing in the channel and potential denitrification rate in the sediments at selected sites on a few dates. Watershed land use was derived from the National Land Cover Data (NLCD) database. Our monthly monitoring results suggest that : (1) TDN, 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) trace gas concentrations are more sensitive indicators that respond to lower levels of nutrient and organic waste contamination than do TDN and DOC. The stable nitrogen isotope and denitrification measurements generally support the trace gas, TDN, and DOC measurements and appear to reflect waste contamination levels in these watersheds. Elevated levels of nitrous oxide and methane 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 and in state and local governments.
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| PRESENTATION |
An Investigation of Site Characteristics Controlling Airflow Into and Out of the Shallow Unsaturated Zone in Response to Atmospheric Pressure Changes |
03/02/2004
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Tillman Jr., F. D. AND J. W. Weaver. An Investigation of Site Characteristics Controlling Airflow Into and Out of the Shallow Unsaturated Zone in Response to Atmospheric Pressure Changes. Presented at 16th National Underground Storage Tank Conference, New Orleans, LA, March 1-3, 2004.
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| Abstract:
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Atmospheric pressure near the land surface is constantly changing, due both to short-term diurnal temperature fluctuations as well as longer-term cycles due to the passage of high-and-low-pressure weather systems. Depending upon soil properties, such as air-filled porosity and air-permeability and site characteristics such as depth to the water table, barometric pressure changes at land surface may be transmitted deep into the unsaturated zone. As subsurface gas responds to changing surface pressure, gas is "breathed" in and out of the unsaturated zone - a process known as "barometric pumping". Periods of falling atmospheric pressure above a leaking underground storage tank site can withdraw unsaturated zone soil gas, carrying with it potentially harmful organic vapors. By this process contaminants will escape from the shallow unsaturated zone faster than they would by pure diffusion alone. Periods of increasing atmospheric pressure increase the rate of contaminant diffusion by lowering the surface where the contaminant concentration is zero below the true ground level (i.e. reducing the diffusion length). Additionally, oxygen from land surface may penetrate the subsurface during rising atmospheric pressure, providing increased supply of electron acceptors to bacteria degrading organic compounds. This study addressed the need for information about how site characteristics affect soil-gas flow in response to natural changes in atmospheric pressure by incorporating time-series surface-pressure data with subsurface porosity, moisture content and air permeability data into a one-dimensional air-flow/particle tracking model. Results indicate that air-permeability and moisture-content values have little effect on airflow in a single-layer, 3.0-m unsaturated zone system, producing a maximum evacuated depth of 12.5 cm for the parameter values simulated. Single-layer airflow is increased in systems having deeper unsaturated zones. Simulations involving a low-permeability, high-moisture-content layer overlaying a more permeable, low-moisture-content layer show increased subsurface airflow, with a maximum depth of 65.0 cm evacuated for the 3-m unsaturated zone.
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| PRESENTATION |
Decision Tool for Riparian Ecosystem Managment in the Mid-Atlantic Highlands |
08/02/2004
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Johnston, J. M., R. S. Parmar, K. Wolfe, P. Kinder, J. Newland, T. DeMoss, AND D. Kemlage. Decision Tool for Riparian Ecosystem Managment in the Mid-Atlantic Highlands. Presented at Ecological Society of America Annual Meeting, Portland, OR, August 1-6, 2004.
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| Abstract:
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In the Canaan Valley Highlands of the Mid-Atlantic, riparian zone restoration has been identified as a critical watershed management practice not only for the ecosystem services provided but also for the potential socioeconomic growth from environmental investment and job creation. The Canaan Valley Institute (CVI) has partnered with the US Environmental Protection Agency to develop a watershed decision tool that evaluates riparian management scenarios via changes in instream habitat quality and aquatic community productivity and stability. The decision tool incorporates expert knowledge, models of system/biotic response and supporting data into a single interface for trade-off evaluation and scenario development. Fisheries endpoints considered include indicator species as well as sport fishes.
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| PRESENTATION |
Decision-Tool for Riparian Ecosystem Management in the Mid-Atlantic Highlands |
08/02/2004
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Johnston, J. M., R. S. Parmar, K. Wolfe, M. C. Barber, B. Rashleigh, M. J. Cyterski, Y. Mohamoud, P. Kinder, J. Newland, T. DeMoss, AND D. Kemlage. Decision-Tool for Riparian Ecosystem Management in the Mid-Atlantic Highlands. Presented at Ecological Society of America Annual Meeting, Portland, OR, August 1-6, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Site Assessment With EPA's on-Line Tools |
03/02/2004
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Weaver, J. W. Site Assessment With EPA's on-Line Tools. Presented at 16th National Underground Storage Tank Conference, New Orleans, LA, March 1-3, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Formation of Halonitromethanes in Drinking Water During Chlorination |
05/23/2004
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Choi, J. AND S. D. Richardson. Formation of Halonitromethanes in Drinking Water During Chlorination. Presented at 52nd American Society for Mass Spectrometry Conference, Nashville, TN, May 23-27, 2004.
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In addition to many other halogenated disinfection by-products (DBPs), a number of halonitromethanes including chlorinated, brominated, and mixed bromochlorinated nitromethanes, have been identified in drinking water. These halonitromethanes, especially the brominated ones, are more cytotoxic and mutagenic than most of the DBPs that are currently regulated in drinking water. In this work, gas chromatography (GC)/mass spectrometry (MS) was used to study the formation of halonitromethanes during the chlorination of laboratory prepared water. The effect of ozonation and elevated bromide concentration on halonitromenthane formation was also investigated.
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| PRESENTATION |
Five-States' Response to a Leaking Underground Storage Tank Scenario |
03/02/2004
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Weaver, J. W. AND D. Mann. Five-States' Response to a Leaking Underground Storage Tank Scenario. Presented at 16th National Underground Storage Tank Conference, New Orleans, LA, March 1-3, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Interactive Habitat Models for Mid-Atlantic Highland Stream Fishes |
08/02/2004
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Rashleigh, B., R. S. Parmar, AND J. M. Johnston. Interactive Habitat Models for Mid-Atlantic Highland Stream Fishes. Presented at Ecological Society of America Annual Meeting, Portland, OR, August 1-6, 2004.
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| Abstract:
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In most wadeable streams of the Mid-Atlantic Highland region of the eastern United States, habitat alteration resulting from development in the watershed is the primary stressor for fish. Models that predict the presence of stream fish species based on habitat characteristics can be useful in watershed management. We developed such a model for thirteen of the most common Mid-Atlantic Highland stream fishes using stepwise multiple logistic regression and seventeen instream habitat variables. The predictive ability of the models (one per species) ranged from 64-87%. In general, the most suitable habitats for these species are characterized by: lower gradient, because this region is mountainous and the very high gradient streams provide less stable habitat; greater stream depth; and lower percentages of fine substrate and undercut banks, which are expected to occur in less disturbed areas. We have incorporated our findings into an interactive software tool that outputs changes in the probability of occurrence for these fish species under various habitat management scenarios.
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| PRESENTATION |
Interactive Habitat Models for Stream Fishes in the Mid-Atlantic Highlands |
08/02/2004
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Rashleigh, B., R. S. Parmar, J. M. Johnston, M. C. Barber, AND M. Cyterski. Interactive Habitat Models for Stream Fishes in the Mid-Atlantic Highlands. Presented at Ecological Society of America Annual Meeting, Portland, OR, August 1-6, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Identification of Disinfection By-Products in Swimming Pool Water |
05/23/2004
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Richardson, S. D., A. D. Thruston Jr., AND F. G. Crumley. Identification of Disinfection By-Products in Swimming Pool Water. Presented at 52nd American Society for Mass Spectrometry Conference, Nashville, TN, May 23-27, 2004.
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In order to kill harmful pathogens, swimming pool water is treated with a disinfectant, such as chlorine or ozone. One of the most commonly used disinfectants is stabilized chlorine (typically trichloro-S-triazinetrione). Trichloro-S-triazinetrione reacts in water to form one mole of cyanuric acid and 3 moles of hypochlorous acid (the active disinfectant). While swimming pools have been disinfected with some form of chlorine for many years, there has been no previous work to comprehensively identify disinfection by-products (DBPs) in swimming pool water. Trihalomethanes have been found previously in pool water and in the blood and exhaled breath of swimmers. In this study, we used GC/MS to comprehensively identify by-products in chlorinated swimming pools to determine what chemicals swimmers are exposed to.
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| PRESENTATION |
Environmental Chemistry: Emerging Contaminants and Current Issues |
05/18/2004
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Richardson, S. D. Environmental Chemistry: Emerging Contaminants and Current Issues. Presented at EnviroAnalysis 2004, Toronto, Canada, May 17-21, 2004.
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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 perfluorooctanoic acid (PFOA), 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.
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| PRESENTATION |
Modeling Leaking Underground Storage Tanks |
03/18/2004
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Weaver, J. W. Modeling Leaking Underground Storage Tanks. Presented at National Research Council Meeting on Environmental Modeling, Washington, DC, March 18, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Issues in Modeling Elemental Mercury Air/Water Exchange |
03/29/2004
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Loux, N. T. Issues in Modeling Elemental Mercury Air/Water Exchange. Presented at 227th American Chemical Society National Meeting, Anaheim, CA, March 28 - April 1, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Workshop on Ground-Water Modeling |
03/18/2004
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Kraemer, S. R. Workshop on Ground-Water Modeling. Presented at U.S. Environmental Protection Agency Region 4, Atlanta, GA, March 18, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Watershed and Water Quality Modeling Technical Support Center |
04/14/2004
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Wool, T. A. Watershed and Water Quality Modeling Technical Support Center. Presented at Best Management Practices Effectiveness Workshop, Washington, DC, April 14-15, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Evaluating the Sensitivity of Screening-Level Vapor Intrustion Models |
06/01/2004
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Weaver, J. W. AND F. D. Tillman Jr. Evaluating the Sensitivity of Screening-Level Vapor Intrustion Models. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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| Abstract:
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Vapor intrusion is defined as the migration of volatile chemicals from the subsurface into overlying buildings. Volatile organic contaminants (VOCs) in soil or ground water can volatilize into soil gas and be transported towards the land surface where it can enter homes or businesses through cracks in basement floors or slabs. These volatile compounds are frequently associated with contamination from leaking underground storage tanks and releases from dry-cleaners and industrial facilities.Under certain circumstances, people living or working above contaminated soil or ground water may be exposed to harmful levels of these vapors. Often, a screening-level model is employed to determine if a potential indoor inhalation exposure pathway exists and, if such a pathway is present, whether long-term exposure increases the occupants' risk for cancer or other toxic effects to an unacceptable level. A popular screening-level algorithm for making such determinations is the Johnson and Ettinger (J&E) model. The EPA Office of Emergency and Remedial Response issues eight spreadsheet variations of the basic Johnson and Ettinger model through their website (http://www.epa.gov/superfund/programs/risk/airmodel/johnson_ettinger.htm). Although the J & E model is appealing because of its simple nature, there are unanswered scientific questions concerning its application:
Does the model consistently produce the "conservative" results necessary in deciding upon further action?
How important are the choices of various input parameters?
Would changes in basic assumptions significantly change model outputs?
To answer these questions, a web-based version of the model is being developed (http://www.epa.gov/athens/onsite) so that the sensitivities and uncertainties of this model can be assessed. A new decision-tree structure drives the model input process, requesting information from the user and selecting subsequent data and models based on user response. This approach to using the model is designed not only to answer the scientific questions by providing best estimates of indoor air concentration, but also to provide upper and lower concentration bounds based upon the ranges of possible inputs. Where multiple conceptual formulations of the model can be used, the analysis also evaluates the sensitivities introduced by the choice of model itself. These results are expected to provide an improved basis for the use of models in a risk screening protocol.
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| PRESENTATION |
Evaluating the Sensitivity of Screening Level Vapor Intrusion Models |
06/01/2004
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Tillman Jr., F. D. AND J. W. Weaver. Evaluating the Sensitivity of Screening Level Vapor Intrusion Models. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Computational Toxicology Objective 2: Developing Approaches for Prioritizing Chemicals for Subsequent Screening and Testing |
06/01/2004
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Weber, E. J. Computational Toxicology Objective 2: Developing Approaches for Prioritizing Chemicals for Subsequent Screening and Testing. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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One of the strategic objectives of the Computational Toxicology Program is to develop approaches for prioritizing chemicals for subsequent screening and testing. Approaches currently available for this process require extensive resources. Therefore, less costly and time-extensive computational approaches must be developed to determine which chemicals or classes of chemicals should be screened and tested first. Three areas where computational approaches will substantially impact on the prioritization process include Quantitative Structure Activity Relationships (QSARs) and other computational approaches, Pollution Prevention strategies, and High Throughput Screening. QSARs have been used to optimize laboratory testing, to provide estimates of missing data in lower tier risk assessment, and to estimate the toxicity of untested chemicals directly from chemical structure. Emerging "omics" technologies have excellent potential to generate information that will inform and improve the QSAR modeling process. In support of pollution prevention strategies, ORD is developing methods to estimate the potential environmental impact of chemicals that are released into the environment. These methods are used to evaluate chemicals for potential harm both to humans and the environment in a life-cycle assessment framework. Regardless of the level of sophistication in the models, the final impact indicators (e.g., a broad range of mid-point effects or final outcomes, such as human deaths, human illnesses, crop damage, water quality issues, air quality issues) could be used to compare a large number of chemicals. Applications of new molecular and other technological advances hold promise for the development of high throughput screens (HTPS). For example, new approaches have the potential for making significant advances over existing screens for Endocrine Disrupting Chemicals (EDCs) in terms of speed, high-throughput capability, sensitivity, reproducibility, and reduction in animal usage in a screening and testing program.
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| PRESENTATION |
Using Canines in Source Detection of Indoor Air Pollutants EPA Science Forum |
06/01/2004
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BIRD, S. L. AND D. L. SPIDLE. Using Canines in Source Detection of Indoor Air Pollutants EPA Science Forum. Presented at EPA Science Forum 2004, Washington, DC, June 01 - 03, 2004.
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| Abstract:
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Scent detection dogs have been used extensively in law enforcement and military applications to detect narcotics and explosives for over thirty years. 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 can serve as a rapid screen to indicate the presence of a substance in air, soil, or even water. Dogs are capable not only of indicating the presence of a compound, but also of moving up-gradient towards the source of the material and discriminating between closely related compounds. Benzene, toluene, ethylene, and xylene, major constituents of gasoline, are frequent culprits related to vapor intrusion into buildings from contaminated groundwater. Since indoor air contamination can also occur from household sources, responsibility is often contested. Canines can provide an effective approach for screening contaminant source location, as well as simply indicating the presence of a contaminant and significantly reducing required sampling costs. This research demonstrates the use of dogs as a tool in vapor intrusion investigations with an emphasis on evaluating the cost-effectiveness of employing them, developing quality assurance strategies in support of their use, and protecting the dogs from exposure to harmful levels of chemicals. This project is a unique application in the use of scent detection canines in an environmental application. A demonstration of canine scent detection capabilities will be provided along with the poster.
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| PRESENTATION |
Protecting Human Health and the Environment on Sioux Tribal Lands: A Partnership of EPA and Tribal Epd |
06/01/2004
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Johnston, J. M., D. Hoff, C. Knightes, R. B. Ambrose Jr., C. Ducheneaux, AND R. Hoogerheide. Protecting Human Health and the Environment on Sioux Tribal Lands: A Partnership of EPA and Tribal Epd. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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| Abstract:
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Through environmental sampling performed by EPA and Cheyenne River Sioux Tribe Environmental Protection Division personnel, mercury contamination in managed pond systems in South Dakota was characterized and risk reduction recommendations were made to protect subsistence fisherman and their families. However, scientific uncertainty remains with regard to the mechanisms of methylation and demethylation within the pond systems, as well as the means of mitigating the biomagnification occurring in aquatic food webs across the region. In a previous model evaluation of the Regional Mercury Cycling Model (R-MCM), it was discovered that models based on the current science underpredict both total mercury concentrations as well as the percent of total mercury present as methylmercury. This suggests that current models are not adequately capturing the processes governing the total loading of mercury to the system or the transformation processes governing methylmercury production. Continued monitoring of managed farm ponds is focused on reducing temporal and spatial uncertainty in model predictions, as well as uncertainty associated with model parameters such as mercury loading (atmospheric and watershed-based) and transformation. To address these key areas of scientific uncertainty, a model comparison is also underway, involving a new Excel spreadsheet-based application based on the Mercury Report to Congress.
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| PRESENTATION |
Protecting Human Health and the Environment on the Cheyenne Sioux Tribal Lands: A Partnership of EPA and Tribal Epd |
06/01/2004
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Johnston, J. M., D. Hoff, C. Knightes, R. B. Ambrose Jr., C. Ducheneaux, AND R. Hoogerheide. Protecting Human Health and the Environment on the Cheyenne Sioux Tribal Lands: A Partnership of EPA and Tribal Epd. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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| Abstract:
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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 for further information.
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| PRESENTATION |
Prediction of Fundamental Assemblages of Mid-Atlantic Highland Stream Fishes |
06/01/2004
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Cyterski, M. J., R. S. Parmar, M. C. Barber, B. Rashleigh, J. M. Johnston, AND K. Wolfe. Prediction of Fundamental Assemblages of Mid-Atlantic Highland Stream Fishes. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
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| Abstract:
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A statistical software tool, the Stream Fish Assemblage Predictor (SFAP), based on stream sampling data collected by the EPA in the mid-Atlantic Highlands, was developed to predict potential stream fish communities using characteristics of the stream and its watershed. Step one in the tool development was a cluster analysis that formed groups of streams with similar fish species. Twenty-three clusters, each defined by a fundamental fish assemblage, resulted. Step two was a discriminant analysis, which produced a system of equations to predict a stream's fundamental fish assemblage (its cluster) based on characteristics of that stream and its watershed (e.g., stream slope, percent forested area in the watershed, stream bank vegetation, latitude, longitude).
The discriminant equations, when tested using our sample data, correctly predicted a stream's fish assemblage with approximately 35% accuracy. The chance of randomly choosing the correct cluster would be approximately 4% (1 chance in 23). The actual stream cluster was one of the three most probable predictions in 65% of the test cases. Randomly, given three choices, one would only have a 3 in 23 chance of picking the correct assemblage (13%).
These predicted fish assemblages can be used to estimate stream health. This software also allows users to investigate potential impacts of environmental restoration or degradation by altering stream and watershed characteristics, then examining changes in the predicted fish community. This tool was developed specifically for stakeholders of the Canaan Valley Institute, West Virginia, but can be implemented by all parties interested in stream fish communities of the Mid-Atlantic Highlands region. This tool is currently available from the Canaan Valley Institute's website at http://www.canaanvi.org/
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| PRESENTATION |
Emerging Drinking Water Disinfection By-Products and New Health Issues |
04/22/2004
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Richardson, S. D. Emerging Drinking Water Disinfection By-Products and New Health Issues. Presented at Florida State University, Tallahassee, FL, April 22, 2004.
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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.
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| PRESENTATION |
Kinetic Control of Oxidation State at Thermodynamically Buffered Potentials in Subsurface Waters |
04/22/2004
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Washington, J. W. Kinetic Control of Oxidation State at Thermodynamically Buffered Potentials in Subsurface Waters. Presented at University of Georgia, Athens, GA, April 22, 2004.
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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.
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| PRESENTATION |
Physics Requires a Simple Low Mach Number Flow to Be Compressible |
06/22/2004
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Frick, W. E. Physics Requires a Simple Low Mach Number Flow to Be Compressible. Presented at Mathematical and Numerical Aspects of Low Mach Number Flows, Porquerolles, France, June 21-25, 2004.
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Radial, laminar, plane, low velocity flow represents the simplest, non-linear fluid dynamics problem. Ostensibly this apparently trivial flow could be solved using the incompressible Navier-Stokes equations, universally believed to be adequate for such problems. Most researchers would, however, simply use the incompressible flow assumption to estimate the velocity as a function of radius and the incompressible Bernoulli equation to compute the pressure gradient.Because this approach does not dynamically determine the velocity, it is fair to ask whether the solution exactly represents such flow or whether the actual laminar velocity will be greater or less than the incompressible velocity. To answer this, it is eminently appropriate to solve the more rigorous compressible problem. If the incompressible flow assumption is robust, it will show that in the limit of zero velocity any compressible contribution decreases more rapidly in importance than incompressible contribution, leading to the incompressible flow limit.
A Lagrangian compressible-flow analysis is used to obtain an analytical solution to the problem. The exact solution shows that for the most natural flow, adiabatic flow, and isothermal and other flows, the true velocity is different from the incompressible velocity, even at the limit of zero velocity. Thermodynamically speaking, only for the very special incompressible case is this untrue. However, it is not difficult to show that assuring incompressible flow would require extraordinary efforts to develop the techniques to precisely modify the flow by adding or extracting heat from the system. Free flow, of which adiabatic flow is the most representative, will not maintain constant density. In fact, in the radial flow problem it can be shown that for adiabatic flow between two parallel plates the pressure gradient is proportional to the divergence of the velocity and there cannot be a pressure gradient without it.
The analytical solution is based on applying Newton's second law of motion, not the Navier-Stokes equations. A robust Navier-Stokes approach must be able to duplicate this result given the same laminar flow assumptions. What it shows is that pressure and density remain linked at low velocity through the equation of state. There is no uncoupling between pressure and density at low velocity. The analytical solution does not contain an incompressible term that becomes large compared to the compressible term at the limit of zero velocity. Given the thermodynamic constraint (adiabatic, isothermal or other flows), or temperature, solving the density problem is equivalent to solving the pressure problem, and vice versa. However, in many instances, density, not pressure, is the independent variable.
Finding a single low-velocity flow phenomenon that cannot be derived from the incompressible paradigm will prove this is more than an academic argument. Invoking the low-velocity Mach number criterion, one frequently finds claims in the literature that the incompressible Navier-Stokes equations adequately represent insect flight. But the compressible model suggests that hovering insects use compression-decompression cycles to gain lift on the downstroke and an assist on the upstroke. This work examines insect flight and offers a glimpse of the future of fluid dynamics after incompressible theory assumes a subordinate role as a special case of compressible flow theory.
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| PRESENTATION |
Physics and Insects Require Compressible Flow |
06/22/2004
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Frick, W. E. Physics and Insects Require Compressible Flow. Presented at Mathematical and Numerical Aspects of Low Mach Number Flows, Porquerolles, France, June 21-25, 2004.
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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.
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| PRESENTATION |
Sediment Modeling Principles and Overview of Bioaccumulation Models |
05/25/2004
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Hayter, E. J. Sediment Modeling Principles and Overview of Bioaccumulation Models. Presented at National Association of Remedial Project Managers Training Conference, Miami Beach, FL, May 24-28, 2004.
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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.
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| PRESENTATION |
Seql Water Resources Vulnerability and Sustainability: Part 1. Modeling Fair Weather Response to Land Use Change and Part 2. Water Resources Vulnerability and Sustainability |
05/04/2004
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Kraemer, S. R. AND Y. Mohamoud. Seql Water Resources Vulnerability and Sustainability: Part 1. Modeling Fair Weather Response to Land Use Change and Part 2. Water Resources Vulnerability and Sustainability. Presented at Sustainable Environment for Quality of Life Meeting, Charlotte, NC, May 4, 2004.
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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.
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| PRESENTATION |
U.S. Nationwide Drinking Water Disinfection By-Product Occurrence Study and New Health Effects Research |
05/19/2004
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Richardson, S. D., A. D. Thruston Jr., S. W. Krasner, AND H. S. Weinberg. U.S. Nationwide Drinking Water Disinfection By-Product Occurrence Study and New Health Effects Research. Presented at EnviroAnalysis 2004, Toronto, ON, CANADA, May 17 - 21, 2004.
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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.
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| PRESENTATION |
Use of Models in the Regulatory Setting |
05/19/2004
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Weaver, J. W. Use of Models in the Regulatory Setting. Presented at National Academy of Science Dispersant Panel, Seattle, WA, May 19, 2004.
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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.
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| PRESENTATION |
Estimating Nitrogen and Tidal Exchange in a North Pacific Estuary With EPA's Visual Plumes |
09/28/2004
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Frick, W. E. AND A. C. Sigleo. Estimating Nitrogen and Tidal Exchange in a North Pacific Estuary With EPA's Visual Plumes. Presented at 3rd International Conference on Marine Waste Water Discharges, Catania, Italy, September 27-October 2, 2004.
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Relatively large fluctuations in temperature, nitrate, and other water properties were observed in August 2000 three kilometers from the entrance jetties to Yaquina Bay, Oregon, USA. Exhibiting periods comparable to the tides, several hypotheses were proposed to explain the variations, including internal tides, ocean patchiness, and Yaquina Bay tidal outflow. The Prych-Davis-Shirazi (Windows) model, PDSW, as found in the US EPA Visual Plumes model, was used to test the viability of the outflow hypothesis. PDSW is a steady state model in which plume development time is short relative to times during which ambient conditions, particularly currents, change significantly. The model was originally designed for relatively small industrial discharges. However, it has been used successfully to assess large power plant cooling flows, with 50m wide discharge channels. The Yaquina Bay jetty is half an order of magnitude wider than that and, at the time of first testing the model on this case, represented the largest known channel to be simulated with the model. Subsequent application to the much larger Columbia River tidal plume shows that it might be useful for understanding even larger outflows. The results indicate that, within the limitations of the model, it is appropriately applied to the Yaquina plume and represents verification evidence for the use of the model when ambient ocean currents are steady. However, where ocean currents change considerably in a few hours, the steady state assumption requires further consideration as plume trajectories will meander horizontally and often fractionate, or become patchy. Data from two depths below the nitrate sensor indicate no vertical temperature gradient to support the internal tide hypothesis. While fluctuating by up to three degrees over tide cycles, temperature changes are relatively abrupt at both levels, without discernible lag. Oceanic patchiness cannot be discounted out of hand but may often be related to the movement of previously discharged estuarine water into the site region as alongshore currents reverse directions. The PDSW analysis supports the tidal Yaquina Bay outflow hypothesis as a cause for nitrate and water property variations near the Yaquina Bay jetties. However, further verification of PDSW focuses on analyzing another data source in the effort to establish that the relatively high bay temperatures, needed to support the plume hypothesis, were recorded. If that effort supports the plume hypothesis, it will suggest that PDSW predictions, while useful for predicting the horizontal penetration of large plumes onto the coastal shelf, underestimate the depth of plume penetration into the water column.
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| PRESENTATION |
Estimating Nitrogen and Tidal Exchange in a North Pacific Estuary With EPA's Visual Plumes Pdsw Model |
09/29/2004
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Frick, W. E., A. C. Sigleo, AND D. T. Specht. Estimating Nitrogen and Tidal Exchange in a North Pacific Estuary With EPA's Visual Plumes Pdsw Model. Presented at 3rd International Conference on Marine Waste Water Discharges, Catania, Italy, September 25-October 2, 2004.
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Accurate assessments of nutrient levels in coastal waters are required to determine the nutrient effects of increasing population pressure on coastal ecosystems. To accomplish this goal, in-field data with sufficient temporal resolution are required to define nutrient sources and sinks, and to ultimately calculate nutrient budgets. Very high temporal resolution data, however, can capture transient events and document unexpected short-term temporal processes. The interpretation of these high density data sets, however, may require complex models. The application of the U.S. EPA Visual Plumes PDSW model output suggests estuarine plumes carry estuarine effluent well offshore, playing an important role in the exchange of estuarine and coastal water. In contrast, evidence is found that internal tides, if present, play a lesser, effectively supporting, role in explaining the variation in water properties near estuaries.
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| PRESENTATION |
The U.S. EPA's Vision for a Beach Forecasting Tool |
09/28/2004
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Frick, W. E., M. Davis, A. P. Dufour, R. S. Lunetta, J. G. Lyon, M. Molina, D. Rockwell, G. N. Stelma Jr., AND X. Tian. The U.S. EPA's Vision for a Beach Forecasting Tool. Presented at 3rd International Conference on Marine Waste Water Discharges3rd International Conference on Marine Waste Water Discharges, Catania, Italy, September 27-October 2, 2004.
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Beach closures due to water quality that exceeds standard limits occur frequently in the United States. These beach closures deprive the public of opportunities for recreational activities and can have a significant impact on local economics. Because of the large number of marine and freshwater beaches in the U.S., the overall impact of beach closures on the nation could be extensive. These undesirable conditions have heightened interest in potential approaches to keeping beach closures to a minimum, while maintaining safe waters for recreational swimming. Multiple studies have shown that the current monitoring approach for maintaining water quality does not fully protect public health. The U.S. Environmental Protection Agency and the U.S. Geological Survey have been actively engaged in developing prognostic and diagnostic tools to effectively determine when poor water quality will occur, so the public can be appropriately notified before they use beach water resources. Now EPA, NOAA, USGS, and other federal and local agencies are combining their efforts to develop a Beach Forecasting Tool (BFT). The BFT is designed to provide information about collecting and analyzing geophysical, morphological, and demographic data that can be used to predict or forecast current and future waste-field patterns arising from anthropogenic and natural sources. A tiered approach has been adopted ranging from relatively accessible empirical models intended for small municipalities and data sparse areas, to more sophisticated and data intensive models for major water bodies and heavily populated regions. For example, an empirical model may relate rainfall events to beach bacteria concentrations statistically to generate short-term forecasts of beach conditions. On the other hand, major urban public agencies may use specifically tailored numerical circulation and bacterial decay models, also brought into the BFT framework, to predict movement of water and the physical stresses on bacteria and pathogens to produce specific forecasts of beach conditions. The goal is to develop and demonstrate a working BFT prototype in 2005. The prototype will include modules to help define the site(s), satellite images, maps, weather maps, internet linkage, etc.; tools to describe and assess current conditions, e.g., bacterial decay calculators; one or more empirical models for application to data sparse sites; and an implementation of integrated source, circulation, and bacterial fate models.
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| PRESENTATION |
A Vision for a Beach Forecasting Tool |
09/28/2004
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Frick, W. E., D. S. Francy, D. Rockwell, D. Schwab, D. Beletsky, AND R. S. Lunetta. A Vision for a Beach Forecasting Tool. Presented at 3rd International Conference on Marine Waste Water Discharges, Catania, Italy, September 27-October 2, 2004.
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The societal value of safe access to swimmable water is intuitive and in many countries it is a legal right. Threats to water quality reduce these recreational opportunities. The risk comes from exposure to waterborne pathogens from a myriad of sources, both human and animal. Different aspects of this public health issue are addressed in detail by public and private organizations. However, except for monitoring and general guidelines, the public has little access to scientific prognoses on the impending conditions of bathing waters. This paper describes work to combine the efforts of several organizations to produce software designed to assist public health officials and the public in general in assessing the likely short-term quality of the nation's local beaches.
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| PRESENTATION |
Watershed Restoration and Fisheries Management: Canaan Valley Institute What If? |
06/01/2004
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Barber, M. C., M. J. Cyterski, J. M. Johnston, Y. Mohamoud, B. Rashleigh, R. S. Parmar, AND K. Wolfe. Watershed Restoration and Fisheries Management: Canaan Valley Institute What If? Presented at Canaan Valley Institute, Wheeling, WV, June 1, 2004.
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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.
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| PRESENTATION |
U.S. Environmental Protection Agency's Computational Toxciology Program Metabolism and Metabonomics |
07/26/2004
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Kenneke, J. F. U.S. Environmental Protection Agency's Computational Toxciology Program Metabolism and Metabonomics. Presented at Imperial College, London, United Kingdom, July 26, 2004.
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The mission of the U. S. Environmental Protection Agency (EPA) is to safeguard public health and the environment from adverse effects that may be caused by exposure to pollutants in the air, water, soil and food. Protecting human health and the environment carries with it the challenge of assessing hundreds of possible hazardous effects for thousands of chemicals. In assessing risk associated with exposure to a chemical or other environmental stressor, there are a number of uncertainties that lie along a continuum beginning with the presence of the chemical in the environment, the uptake and distribution of the chemical in the organism or human or environment, the presence of the active chemical at a target site, and the series of biological events that lead to the manifestation of an adverse outcome that can be used for risk assessment. The large number of chemicals that the Agency must consider under many different regulations together with the large cost of test batteries limits the full use of these test methods to only a small number of chemicals. The end result is that the Agency is being forced to prioritize and reduce toxicity-testing requirements for potentially hazardous chemicals - including chemicals for which little if any data exists.In a response to these issues, the EPA's Office of Research and Development (ORD) has implemented a Computational Toxicology Program (CompTox) to apply novel technologies derived from computational chemistry, molecular biology and systems biology to toxicological risk assessment. The overall goal of the program is to use emerging technologies to improve quantitative risk assessment and reduce uncertainties in the source to adverse outcome continuum. A predominant theme of CompTox is on the use of "omic" tools as early indicators of exposure and effects due to anthropogenic chemicals.
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| PRESENTATION |
Transcriptional Profiling of Arabidopsis Thaliana Root Responses to Munitions |
06/11/2004
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Ekman, D. R., W. W. Lorenz, A. E. Przybyla, N. L. Wolfe, S. C. McCutcheon, AND J. D. Dean. Transcriptional Profiling of Arabidopsis Thaliana Root Responses to Munitions. Presented at American Ecological Engineering Society Fourth Annual Meeting, Fayetteville, AR, June 9-12, 2004.
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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.
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| PRESENTATION |
Subsurface Contamination and the Internet |
06/15/2004
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Weaver, J. W. Subsurface Contamination and the Internet. Presented at National Science Foundation Environmental Chemistry Workshop, Atlanta, GA, June 15, 2004.
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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.
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| PRESENTATION |
Polymerase Chain Reaction (Pcr) Technology in Visual Beach |
10/14/2004
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Molina, M. AND W. E. Frick. Polymerase Chain Reaction (Pcr) Technology in Visual Beach. Presented at National Beaches Conference, San Diego, CA, October 13-15, 2004.
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In 2000, the US Congress passed the Beaches Environmental Assessment and Coastal Health Act under which the EPA has the mandate to manage all significant public beaches by 2008. As a result, EPA, USGS and NOAA are developing the Visual Beach program which consists of software equipped with descriptive, diagnostic, and prognostic tools and models to help health officials and the public understand, address, and ultimately prevent beach closures. One goal of the program is to provide end users, public health officials, environmental monitoring organizations, and other interested individuals with the information to understand, utilize, and benefit from new Real Time (RT)-PCR technology. This methodology allows identification and quantification of specific fecal indicator bacteria, such as Enterococcus species and Escherichia coli, in two to three hours compared to 24 to 48 hours with conventional membrane filtration methods. In Visual Beach, the software component dedicated to RT-PCR input provides tools for compiling data and for accessing the latest advances in the methodology including quality control parameters, with the aim to achieve technological standardization across users. The PCR component also offers links designed to acquire information for conducting water monitoring programs, as well as guidance on the application of the results into other compartments of the program to obtain predictive information. The ultimate goal will be to use PCR results to reset initial and boundary conditions for the empirical and numerical bacterial decay and transport models planned for Visual Beach.
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| PRESENTATION |
Visual Beach: Software for Achieving Beach Aesthetic and Public Health Protection |
10/15/2004
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Frick, W. E. AND M. Molina. Visual Beach: Software for Achieving Beach Aesthetic and Public Health Protection. Presented at National Beaches Conference, San Diego, CA, October 13-15, 2004.
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The Beaches Environmental Assessment and Coastal Health Act of 2000 directs the EPA to assure that 100% of significant public beaches are managed by 2008. Under the Act EPA is developing a program to monitor beach water quality and strategies for timely notification of the public when bacterial contamination poses danger to bathers. EPA and other institutions, including USGS and NOAA, are developing the Visual Beach program, software to include descriptive, diagnostic, and prognostic tools and models to help health officials and the public to better understand, address, and ultimately prevent beach closures. Work on a prototype began in Spring, 2004. Seeking to support small and large communities alike, the prototype is organized into topical areas, tabs and sub-tabs, of increasing data and resource requirements. Its entry-level descriptive component helps users acquire maps and satellite or camcorder images and identify issues likely to be relevant to the local area, thus customizing Visual Beach to local constraints and conditions. It provides access to some public health data bases and recites procedures for communicating with the public. Diagnostic tools include data links for acquiring information on contaminant sources known to affect specific beaches. It is designed to display current conditions, including sunlight intensity, stream flows, and weather, and includes calculators for estimating bacterial mortality. A subtab is dedicated to emerging PCR technology. Finally, it includes prognostic tools: adaptable empirical models will be designed to be accessible to most communities while sophisticated hydrodynamic models will provide detailed beach condition forecasts for large urban areas.
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| PRESENTATION |
The Next Generation of Drinking Water Disinfection By-Products and Health Issues: Gordon Conference |
06/28/2004
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Richardson, S. D. The Next Generation of Drinking Water Disinfection By-Products and Health Issues: Gordon Conference. Presented at Gordon Research Conference, Environmental Sciences: Water, Plymouth, NH, June 27-July 2, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Response of Sedimentary Microbial Communities to Different Land Use Practices Affecting Headwater Streams in Georgia |
06/15/2004
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Molina, M., R. A. Burke Jr., AND J. Molinero. Response of Sedimentary Microbial Communities to Different Land Use Practices Affecting Headwater Streams in Georgia. Presented at American Society of Limnology and Oceanography 2004 Summer Meeting, Savannah, GA, June 13-18, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Distribution of Chiral PCBs in Selected Tissues in the Laboratory Rat |
09/06/2004
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Lehmler, H. J., I. KaniaKorwel, J. Avants, K. C. Hornbuckle, W. W. Sulkowski, L. W. Robertson, AND A. W. Garrison. Distribution of Chiral PCBs in Selected Tissues in the Laboratory Rat. Presented at 24th International Symposium on Halogenated Environmental Organic Pollutants and POPs, Berlin, Germany, September 6-10, 2004.
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Polychlorinated biphenyls (PCBs) were manufactured for a large number of technical applications including for use in transformers and capacitors. The widespread commercial utilization of PCBs and their persistence in the environment have resulted in their worldwide distribution. Physicochemical characteristics, such as lipophilicity and stability towards biological and thermal degradation, have resulted in their accumulation in the food chain, raising concerns about human health effects. Animal and epidemiological studies have implicated PCBs in a number of human disease processes, such as carcinogenesis and atherosclerosis. However, mechanisms of PCB toxicity are still poorly understood, partly because technical PCB products contain a complex mixture of the possible 209 PCB derivatives or congeners. One of the most intriguing, but frequently overlooked, aspects of PCB toxicity is related to the existence of chiral PCB congeners, possessing at least three ortho (to the biphenyl bridge) chlorine atoms. Racemic PCBs in this group have been implicated in developmental and neurotoxic effects. Two studies with individual congeners have shown that the (+)-enantiomer of PCB 84 and 139 are selectively enriched in tissues, e.g. the liver, of laboratory animals. However, nothing is currently known about the distribution and enrichment of chiral PCBs after administration of a complex PCB mixture to laboratory animals such as the rat. The present study investigates the enantiomeric fraction of PCBs 91, 95 and 149 in male rats after administration of (a) Aroclor 1254 and (b) an environmental mixture obtained from soil contaminated with Chlorofen, a Polish PCB mixture.
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| PRESENTATION |
Enantioselective Elimination of Fipronil and Selected Organochlorines By Rainbow Trout (Oncorhynchus Mykiss) |
11/14/2004
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Konwick, B. J., A. T. Fisk, A. W. Garrison, J. Avants, AND M. C. Black. Enantioselective Elimination of Fipronil and Selected Organochlorines By Rainbow Trout (Oncorhynchus Mykiss). Presented at 25th Annual Meeting of the Society of Environmental Toxicology and Chemistry, Portland, OR, November 14-18, 2004.
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Fipronil is a phenylpyrazole pesticide widely used in applications such as rice culture, turf grass management, and residential pest control with a high probability to contaminate aquatic environments. Fipronil has moderate partitioning (log Kow = 4.01) for accumulation in biota; however, limited information exists on its toxicokinetics (i.e., uptake, elimination, biotransformation) in aquatic species. As a chiral molecule, fipronil is released into the environment as a racemic mixture, containing 50% of each enantiomer. Enantiomers have identical physical-chemical properties and abiotic degradation rates, but usually differ in their biological activities. Biological processes such as metabolism in aquatic species can therefore lead to enriched elimination of one enantiomer of a chiral pesticide. Here, laboratory experiments involved exposure (32 days) of rainbow trout (Oncorhynchus mykiss) to racemates of fipronil and selected organochlorine pesticides and PCBs followed by 128 days depuration to examine the enantiomer-specific biotransformation and elimination of these compounds. Bioaccumulation of each chemical, enantiomeric fractions (EFs), and log Kow - log half-life relationships will be measured over time. We expect residues to deviate from racemic (EF = 0.5), demonstrating that aquatic species can eliminate fipronil and other chiral compounds enantioselectively; this may indicate a greater metabolic capability of aquatic biota than previously recognized.
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| PRESENTATION |
Enantiomer-Specific Effects of Chiral Pollutants |
11/14/2004
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Garrison, A. W., D. R. Ekman, J. F. Kenneke, AND C. S. Mazur. Enantiomer-Specific Effects of Chiral Pollutants. Presented at 25th Annual Meeting of the Society of Environmental Toxicology and Chemistry, Portland, OR, November 14-18, 2004.
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Enantiomers, the mirror image isomers of chiral pollutants, are known to be selective in their interaction with other chiral molecules, including enzymes and other biochemicals. Considerable research has shown, for example, that chiral pesticides are degraded selectively by microbes, leading to differential environmental persistence of the enantiomers. Enantioselectivity is also often observed in the residues of chiral pesticides and PCBs in animal tissues - the residues of several chiral PCBs in various tissues of rats injected with Aroclor 1254 were enantioselective. But, outside the pharmaceutical area, there has been little research on the effects of separate enantiomers. To distinguish these effects, it is necessary to use separate enantiomers, in our case separated by preparative HPLC. Measurements of endocrine disruptor (ED) activity of the enantiomers of several pesticides separated in this way have shown significant selectivity. Currently, we are measuring the toxicological selectivity of the enantiomers of vinclozolin, fipronil and other pesticides toward the luminescent bacterium V.fisheri using the Microtox assay system. In addition, vinclozolin and its enantiomers are being exposed to the Japanese medaka fish, after which the fish liver microsomal material is being assayed for cytochrome P450 activity. There will be corresponding assays using medaka DNA microarrays for indications of gene expression, and metabonomic measurements using high resolution NMR that will allow us to observe changes in the endogenous metabolites in the livers after exposure of the fish to vinclozolin and its enantiomers. Another project involves measurement of the enantioselectivity of certain conazoles, members of an important class of azole fungicides, upon reaction with the cytochrome P450 enzymes of rat microsomal material. Preliminary chromatographic analysis indicates enantioselectivity in the conazole reactivity.
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| PRESENTATION |
NOx and CO Emissions from Cerrado Plant Litter |
07/26/2004
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Kisselle, K. W., R. G. Zepp, R. A. Burke Jr., M. Molina, AND M. Bustamante. NOx and CO Emissions from Cerrado Plant Litter. Presented at LBA Science Meeting, Brasilia, Brazil, July 26-28, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Response of the Soil Microbial Community to Fertilization Practices in Agricultural and Native Cerrado Systems in Brazil |
07/26/2004
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Molina, M., L. Viana, M. Bustamante, AND R. G. Zepp. Response of the Soil Microbial Community to Fertilization Practices in Agricultural and Native Cerrado Systems in Brazil. Presented at LBA Science Meeting, Brasilia, Brazil, July 26-26, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Biogeochemical Indicators of Organic Waste Contamination in Georgia Piedmont Streams |
11/01/2004
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Burke Jr., R. A. AND J. Molinero. Biogeochemical Indicators of Organic Waste Contamination in Georgia Piedmont Streams. Presented at Soil Science Society of America Annual Meeting, Seattle, WA, October 31-November 4, 2004.
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| Abstract:
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We monitored concentrations of nitrous oxide, methane, carbon dioxide, nutrients and other parameters (T, conductivity, dissolved oxygen, alkalinity, pH, DOC, DON, flow rate) in 17 headwater streams (watershed sizes from 0.5 to 3.4 km2) of the South Fork Broad River, Georgia watershed on a monthly basis for a year. We also measured the stable nitrogen isotope ratio of plants growing in the channel and potential denitrification rate in the sediments at selected sites on a few dates. Watershed land use was derived from the National Land Cover Data (NLCD) database. Our monthly monitoring results suggest that : (1) TDN, 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) trace gas concentrations are more sensitive indicators that respond to lower levels of nutrient and organic waste contamination than do TDN and DOC. The stable nitrogen isotope and denitrification measurements generally support the trace gas, TDN, and DOC measurements and appear to reflect waste contamination levels in these watersheds. Elevated levels of nitrous oxide and methane 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.
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| PRESENTATION |
Characterizing the Conformational and Electronic Properties of Conazole Fungicides |
11/01/2004
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Bailey, G. W. AND T. M. Jenkins. Characterizing the Conformational and Electronic Properties of Conazole Fungicides. Presented at Soil Science Society of America Annual Meeting, Seattle, WA, October 31-November 4, 2004.
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| Abstract:
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Conazole fungicides have important environmental and human health considerations including chemical reactivity and transformation pathways. The electronic and conformational properties of an organic molecule determines in conjunction with solvent properties, its chemical reactivity and transformation pathways. Mapping of properties on a molecular surface provides a 3-dimensional graphic representation of each property superimposed on the chemical structure of the molecule. Surface properties - partial atomic charges, lipophilic potential, electrostatic potential, hydrogen bonding sites, hydrogen acceptor/acceptor donor density, local curvature, and cavity depth - were computed and mapped onto the chemical structure of a 1,2,4-triazole fungicide - bromuconazole - using MOLCAD PM3. Graphical representation of each property at various spatial orientations will demonstrate the utility of the approach to gain insight into molecular properties of conazole fungicides and other small organic molecules.
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| PRESENTATION |
Selection of Candidate Eutrophication Models for Total Maximum Daily Loads Analyses |
10/12/2004
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Carousel, R. F. Selection of Candidate Eutrophication Models for Total Maximum Daily Loads Analyses. Presented at Eighth International Symposium on Fish Physiology, Toxicology, and Water Quality, Chonqing, China, October 12-14, 2004.
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| Abstract:
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A tiered approach was developed to evaluate candidate eutrophication models to select a common suite of models that could be used for Total Maximum Daily Loads (TMDL) analyses in estuaries, rivers, and lakes/reservoirs. Consideration for linkage to watershed models and ecological endpoints were to be included in the assessment. Four tiers including 1) identification of candidate models; 2) developing a series of minimum requirements including well developed representations for sediment, nutrients, and some plankton species; internally or successfully coupled to a hydrodynamic model, documentation of algorithms; 3) documentation including operational instructions and flow of execution, have had at least 3 applications during the last 10 years with one other than the developer; and 4) source code analysis including non-proprietary nature, must be a one-time purchase without a run-time license, PC-compatible platform is required and for reservoir and estuary models, multi-dimensional capability. A comprehensive review was undertaken and over 250 models were identified as possible candidates. From the initial review a total of 7 contained the minimum requirements for TDML analyses.
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| PRESENTATION |
Capture Zone Delineation for Pumping Wells Revisited: Choosing Between Simple Methods and Modeling |
09/20/2004
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Kraemer, S. R. Capture Zone Delineation for Pumping Wells Revisited: Choosing Between Simple Methods and Modeling. Presented at Ground Water Council Annual Forum, Charleston, SC, September 18-22, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Formation of Halonitromethanes in Drinking Water |
11/15/2004
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Choi, J. AND S. D. Richardson. Formation of Halonitromethanes in Drinking Water. Presented at American Water Works Association Water Quality Technical Conference, San Antonio, TX, November 14-18, 2004.
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| Abstract:
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In addition to many other halogenated disinfection by-products (DBPs), a number of halonitromethanes including chlorinated, brominated, and mixed bromochlorinated nitromethanes, have been identified in drinking water. These halonitromethanes, especially the brominated ones, are more cytotoxic and mutagenic than most of the DBPs that are currently regulated in drinking water. In this work, GC/MS was used to study the formation of halonitromethanes during the chlorination of laboratory prepared water. The effect of ozonation and elevated bromide concentration on halonitromethane formation was investigated.
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| PRESENTATION |
On-Line Calculators for Site Assessment Calculations |
09/14/2004
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Weaver, J. W. On-Line Calculators for Site Assessment Calculations. Presented at US EPA Region 3 RCRA Corrective Action Workshop, Rocky Gap, MD, September 14-16, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Bioassay-Directed Chemical Analysis for Identifying Drinking Water Disinfection By-Products of Health Concern |
09/22/2004
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Richardson, S. D. Bioassay-Directed Chemical Analysis for Identifying Drinking Water Disinfection By-Products of Health Concern. Presented at Association of Official Analytical Chemists International Conference, St. Louis, MO, September 22, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Emerging Drinking Water Disinfection By-Products from Alternative Disinfectants and New Toxicity Studies |
09/20/2004
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Richardson, S. D. Emerging Drinking Water Disinfection By-Products from Alternative Disinfectants and New Toxicity Studies. Presented at Virginia American Water Works Association Conference, Richmond, VA, September 20, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Emerging DBPs of Health Concern |
09/24/2004
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Richardson, S. D. Emerging DBPs of Health Concern. Presented at CIIT Centers for Health Research, Research Triangle Park, NC, September 24, 2004.
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| Abstract:
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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.
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| PRESENTATION |
EPA Contaminated Sediment Remediation Guidance for Hazardous Waste Sites |
10/09/2004
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Hayter, E. J. EPA Contaminated Sediment Remediation Guidance for Hazardous Waste Sites. Presented at American Society of Civil Engineers Contaminated Sediment Workshop, Fairport, IA, October 7-9, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Hydrodynamic and Transport Modeling Study in a Highly Stratified Estuary |
12/15/2004
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Arega, F. AND E. J. Hayter. Hydrodynamic and Transport Modeling Study in a Highly Stratified Estuary. Presented at Fourth International Symposium on Environmental Hydraulics, Hong Kong, China, December 15-18, 2004.
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| Abstract:
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This paper presents the preliminary results of hydrodynamic and salinity predictions and the implications to an ongoing contaminated sediment transport and fate modeling effort in the Lower Duwamish Waterway (LDW), Seattle, Washington. The LDW is highly strati-fied when freshwater inflows are greater than 28 m3/s; otherwise, the lower portion of the estuary grades into a partially stratified type. The LDW is located in the heart of the Seattle industrial area and numerous industrial, manufacturing and combined sewer outfalls have contributed to contamination of the waterway. The primary purpose of this hydrodynamic modeling was to test the capability of a public domain, three-dimensional, hydrodynamic and transport and fate model in simulating the highly stratified flow conditions in the LDW. Model predictions were compared with observed water surface elevations, measured current and salinity distribution time series. The comparison shows that the model reasonably reproduces the existing circulation patterns in the study area under low to medium freshwater discharges, but over predicts the amount of vertical mixing under high freshwater discharge conditions.
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| PRESENTATION |
Habitat Probabilistic Index Models for Stream Fish Population Assessment |
10/20/2004
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Rashleigh, B. Habitat Probabilistic Index Models for Stream Fish Population Assessment. Presented at Seminar at the University of Georgia Environmental Health Sciences Department, Athens, GA, October 20, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Modeling Ground Water/Surface Water Interactions from Well to Watershed Scales: Implications for Safe and Clean Water |
11/05/2004
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Kraemer, S. R. Modeling Ground Water/Surface Water Interactions from Well to Watershed Scales: Implications for Safe and Clean Water. Presented at Kansas State University Symposium: Water, Policy, and People, Manhattan, KS, November 5, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Model Selection and Usage at Lust Sites |
11/05/2004
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Weaver, J. W. Model Selection and Usage at Lust Sites. Presented at US EPA Region 3 LUST Conference, Rocky Gap, MD, November 3-5, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Impacts of Sediment/Water Partitioning on Spectral Properties of Dissolved Organic Matter |
11/19/2004
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Shank, G. C., R. G. Zepp, R. F. Whitehead, AND M. A. Moran. Impacts of Sediment/Water Partitioning on Spectral Properties of Dissolved Organic Matter. Presented at 50th Anniversary Celebration of the National Research Council Associateship Program, Washington, DC, November 19, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Watershed and Water Quality Modeling Technical Support Center Overview |
11/18/2004
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Wool, T. A. Watershed and Water Quality Modeling Technical Support Center Overview. Presented at Region 3 State Water Directors Meeting, Leesburg, VA, November 18, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Sizing Riparian and Other Vegetative Buffers for Land Development |
11/23/2004
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McCutcheon, S. C. Sizing Riparian and Other Vegetative Buffers for Land Development. Presented at University of Alabama Student Chapter of the American Society of Civil Engineers, Tuscaloosa, AL, November 23, 2004.
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| Abstract:
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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.
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| PRESENTATION |
Subsurface Nitrogen Transport at a Swine Cafo: Integrating Stratigraphy, Geomorphology, Geochemistry, and Geohydrology Tools |
12/06/2004
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TESORIERO, A. J., T. SPRUILL, S. HARDEN, S. R. KRAEMER, H. E. MEW, AND K. FARRELL. Subsurface Nitrogen Transport at a Swine Cafo: Integrating Stratigraphy, Geomorphology, Geochemistry, and Geohydrology Tools. Presented at EPA Regional Science Workshop on Animal Feeding Operations (AFOs) - Science and Technical Support Needs, College Park, MD, December 06 - 09, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Introduction and Theory of Habitat Suitability/Bmp Tool |
12/14/2004
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RASHLEIGH, B. Introduction and Theory of Habitat Suitability/Bmp Tool. Presented at Fisheries Management and Habitat Restoration in the Mid-Atlantic Highlands Meeting, Thomas, WV, December 14 - 16, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Applications of the Habitat Suitability Tool |
12/14/2004
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RASHLEIGH, B. Applications of the Habitat Suitability Tool. Presented at Fisheries Management and Habitat Restoration in the Mid-Atlantic Highlands Meeting, Thomas, WV, December 14 - 16, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Model Selection and Usage at Lust Sites |
12/16/2004
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WEAVER, J. W. Model Selection and Usage at Lust Sites. Presented at Interstate Technology and Regulatory Council MTBE Training Course, Denver, CO, December 16 - 17, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Mtbe Plume Formation: Transport and Modeling Considerations |
12/16/2004
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WEAVER, J. W. Mtbe Plume Formation: Transport and Modeling Considerations. Presented at Interstate Technology and Regulatory Council MTBE Training Course, Denver, CO, December 16 - 17, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Using Dna to Identify Sources of Pathogen Contamination |
06/01/2004
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JOHNSON, B. AND M. MOLINA. Using Dna to Identify Sources of Pathogen Contamination. Presented at EPA Science Forum 2004, Washington, DC, June 01 - 03, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Visual Beach: Software for Achieving Beach Aesthetics and Public Health Protection |
10/14/2004
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FRICK, W. E. AND M. MOLINA. Visual Beach: Software for Achieving Beach Aesthetics and Public Health Protection. Presented at National Beaches Conference, San Diego, CA, October 13 - 15, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PRESENTATION |
Coral Condition: How to Fathom the Decline of Coral Reef Ecosystems |
12/07/2004
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FISHER, W. S., D. L. SANTAVY, J. E. ROGERS, L. M. OLIVER, AND R. G. ZEPP. Coral Condition: How to Fathom the Decline of Coral Reef Ecosystems. Presented at Special Corals Biocriteria Seminar, EPA Office of Science and Technology, Washington, DC, December 07, 2004.
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| Abstract:
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Coral reefs have experienced unprecedented levels of bleaching, disease and mortality during the last three decades. The goal of EPA-ORD research is to identify the culpable stressors in different species, reefs and regions using integrated field and laboratory studies.
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| PRESENTATION |
Meeting at Portland, or: Coral Responses to Climate and Land Use Changes |
11/14/2004
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FISHER, W. S., D. L. SANTAVY, J. E. ROGERS, AND R. G. ZEPP. Meeting at Portland, or: Coral Responses to Climate and Land Use Changes. Presented at Society of Toxicology and Chemistry National Meeting, Portland, OR, November 14 - 18, 2004.
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| Abstract:
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Coral reefs in the Florida Keys have been surveyed for occurrence of bleaching and disease, and additional indicators are being applied across the Keys to characterize the status of coral condition. Studies on cultured symbiotic algae have demonstrated combined effects of temperature and UV-R on growth rates and survival. Laboratory studies are designed to compare the effects of temperature, light penetration, and water quality on various coral species from the Florida Keys.
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| PRESENTATION |
Assessing the Impacts of Local and Global Stressors on Coral Reefs in American Samoa |
11/16/2004
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MIELBRECHT, E., L. HANSEN, G. DIDONATO, E. DIDONATO, N. ADAMS, AND R. G. ZEPP. Assessing the Impacts of Local and Global Stressors on Coral Reefs in American Samoa. Presented at Society of Environmental Toxicology and Chemistry National Meeting, Portland, OR, November 14 - 18, 2004.
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| Abstract:
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The practical goal of this project is to aid natural resource managers in developing adaptation strategies to better protect marine resources from global warming. The question that arises is do these local environmental pressures alter the amount of coral bleaching and subsequent recovery or mortaility in the near shore waters of Tutuila Island in American Samoa.
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| PRESENTATION |
No Fluxes from Savannas of Central Brazil (Cerrado) Subjected to Nitrogen and Phosphorus Fertilization |
07/27/2004
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KOZOVITS, A. R., L. T. VIANA, D. M. SOUSA, A. S. PINTO, M. M. BUSTAMANTE, AND R. G. ZEPP. No Fluxes from Savannas of Central Brazil (Cerrado) Subjected to Nitrogen and Phosphorus Fertilization. Presented at Third LBA Scientific Conference, Brasilia, BRAZIL, July 27 - 29, 2004.
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| Abstract:
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The objective of our study was to determine the long-term effects of nutrient addition (N and N+P)in native Cerrado area on N oxides fluxes from soil to the atmosphere.
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| PRESENTATION |
Trace Gas Emissions from the Soil Related to Land-Use Changes in the Cerrado Region |
07/27/2004
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KOZOVITS, A. R., L. T. VIANA, D. M. SOUSA, M. M. BUSTAMANTE, AND R. G. ZEPP. Trace Gas Emissions from the Soil Related to Land-Use Changes in the Cerrado Region. Presented at Third LBA Scientific Conference, Brasilia, BRAZIL, July 27 - 29, 2004.
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| Abstract:
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The effect of conversion of large native Cerrado areas into croplands on the magnitude and dynamics of soil trace gases emissions was investigated.
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| PRESENTATION |
Interactions of Changing Climate and Ultraviolet Radiation in Aquatic and Terrestrial Biogeochemical Cycles |
07/11/2004
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ZEPP, R. G. Interactions of Changing Climate and Ultraviolet Radiation in Aquatic and Terrestrial Biogeochemical Cycles. Presented at American Society for Photobiology National Meeting, Seattle, WA, July 11 - 15, 2004.
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| Abstract:
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During the past decade interest has developed in the interactive effects of climate change and UV radiation on aquatic and terrestrial biogeochemical cycles. This talk used selected case studies to illustrate approaches that are being used to investigate these intriguing processes in the laboratory and field.
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| PRESENTATION |
Chromophoric Dissolved Organic Matter (Cdom) Derived from Decomposition of Various Vascular Plant and Algal Sources |
05/17/2004
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ZEPP, R. G., C. SHANK, M. A. MORAN, W. SHELDON, D. KOOPMANS, AND E. STABENAU. Chromophoric Dissolved Organic Matter (Cdom) Derived from Decomposition of Various Vascular Plant and Algal Sources. Presented at Conference on Chromophoric Dissolved Organic Matter as an Indicator of Ballast Water Exchange, Edgewater, MD, May 17, 2004.
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| Abstract:
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Chromophoric dissolved organic (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.
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| PRESENTATION |
Impacts of Global Change on UV Exposure in Coastal Shelf Regions of the Southeastern United States |
03/16/2004
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ZEPP, R. G. Impacts of Global Change on UV Exposure in Coastal Shelf Regions of the Southeastern United States. Presented at NHEERL-GED Seminar Series, Gulf Breeze, FL, March 16, 2004.
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| Abstract:
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Global change has a variety of impact on UV exposure in coastal shelf regions of the southeastern United States. Changes in solar UV reaching the water surface have been caused by human alterations of atmospheric composition such as depletion of the ozone layer.
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| PRESENTATION |
Seagrass and Cdom in the Florida Keys |
01/26/2004
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ZEPP, R. G., E. STABENAU, M. A. MORAN, AND D. KOOPMANS. Seagrass and Cdom in the Florida Keys. Presented at Second Annual Conference on the Effects of Combined Sea Temperature, Light, and Carbon Dioxide on Coral Bleaching, Settlement and Growth, Lee Stocking Island, BAHAMAS, January 26 - 29, 2004.
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| Abstract:
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Seagrasses play a variety of important ecological roles in coastal ecosystems. Here we present evidence that seagrass detritus from the widespread species, Thalassia testudinum, is an important source of ocean color and UV-protective substances in a low latitude coastal shelf region of the United States.
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| PRESENTATION |
Interactions of Solar UV Radiation and Dissolved Organic Matter in Aquatic Environments |
03/01/2004
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ZEPP, R. G. Interactions of Solar UV Radiation and Dissolved Organic Matter in Aquatic Environments. Presented at University of Minnesota, Department of Chemistry Seminar Series, Minneapolis, MN, March 01, 2004.
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| Abstract:
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Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the environmental cycling of carbon, oxygen, sulfur, and various trace metals in the aquatic environment. This talk will discuss kinetic and mechanistic approaches that are used to study these intriguing photoreactions in the laboratory and field.
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| PRESENTATION |
Interactions of Light and Chemical Reactions in the Aquatic Environment: Kinetic and Mechanistic Aspects |
02/11/2004
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ZEPP, R. G. Interactions of Light and Chemical Reactions in the Aquatic Environment: Kinetic and Mechanistic Aspects. Presented at Lecture at the University of Georgia, Department of Chemistry Seminar Series, Athens, GA, February 11, 2004.
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| Abstract:
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Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the environmental cycling of carbon, oxygen, sulfur, and various trace metals in the aquatic environment. This talk will discuss kinetic and mechanistic approaches that are used to study these intriguing photoreactions in the laboratory and field.
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| PRESENTATION |
Bioaccumulation and Enantioselective Biotransformation of Fipronil By Rainbow Trout (Oncorhynchus Mykiss) |
10/12/2004
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KONWICK, B. J., A. T. FISK, J. K. AVANTS, J. M. LONG, AND A. W. GARRISON. Bioaccumulation and Enantioselective Biotransformation of Fipronil By Rainbow Trout (Oncorhynchus Mykiss). Presented at Fish Physiology, Toxicology, and Water Quality Proceedings of the Eighth International Symposium, Chongqing, CHINA, October 12 - 14, 2004.
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| Abstract:
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Dietary accumulation and enantioselective biotransformation was determined for rainbow trout (Oncorhynchus mykiss) exposed to fipronil, a widely used chiral pesticide. Measurement of the fish carcass tissue (whole fish minus GI tract and liver) showed a rapid accumulation of fipronil at microgram per gram concentrations during the 32 day uptake phase. The low biomagnification factor (0.05) and short depuration half-life (0.58 d) determined for fipronil indicated a rapid clearance of this compound by the fish, thus fipronil would not be expected to biomagnify in the food chain.
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| PRESENTATION |
Mammalian Metabolism and Distribution of Perfluorooctyl Ethanol (8-2 Telomer Alcohol) and Its Oxidation Metabolites |
10/08/2004
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HENDERSON, W. M., S. E. DUIRK, E. J. WEBER, AND M. A. SMITH. Mammalian Metabolism and Distribution of Perfluorooctyl Ethanol (8-2 Telomer Alcohol) and Its Oxidation Metabolites. Presented at Southeastern Chapter of the Society of Toxicology Meeting, Atlanta, GA, October 08, 2004.
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| Abstract:
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There is no abstract for this product. If further information is requested, please refer to the bibliographic citation and contact the person listed under Contact field.
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| PUBLISHED REPORT |
A Study on the Accumulation of Perchlorate in Young Head Lettuce |
09/30/2004
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HUTCHINSON, S. L. A Study on the Accumulation of Perchlorate in Young Head Lettuce. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-03/003 (NTIS PB2005-105427), 2004.
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| Abstract:
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The overall objective of this study was to demonstrate in a greenhouse study the potential for incorporation of perchlorate from aqueous solutions of 10, 50, 100, 500, 1,000, 5,000, and 10,000 ppb into an agricultural food crop (lettuce; Lactuca sativa), which is typically grown under irrigated conditions. A sand matrix amended with water containing known amounts of perchlorate was used as the growth medium to accentuate uptake. The successful demonstration of the uptake and accumulation of perchlorate by lettuce in the greenhouse study was seen as information that other researchers could use in further research on uptake of perchlorate by lettuce grown under field conditions.
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| PUBLISHED REPORT |
A Comprehensive Nonpoint Source Field Study for Sediment, Nutrients, and Pathogens in the South Fork Broad River Watershed in Northeast Georgia |
09/01/2004
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Smith, C. N., F. E. Stancil, D. L. Spidle, P. D. Smith, B. E. Kitchens, H. P. Kollig, L. Smith, S. Senter, M. Cyterski, L. M. Prieto, D. C. Bouchard, K. Wolfe, R. S. Parmar, Y. Mohamoud, 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 in Northeast Georgia. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-04/026 (NTIS PB2005-101441), 2004.
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| Abstract:
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This technical report provides a description of the field project design, quality control, the sampling protocols and analysis methodology used, and standard operating procedures for the South Fork Broad River Watershed (SFBR) Total Maximum Daily Load (TMDL) project. This watershed is located in the Savannah River Basin and the project constitutes Task 12556, Field Research Program. A TMDL is the sum of the individual pollutant waste load allocation for point sources and load allocation for nonpoint sources and natural background, with a margin of safety (CWA Section 303 (d)(1)(C), EPA 1999). The field study reported was part of a project designed to develop sampling protocols and predictive models, and to establish a comprehensive database to field test the developed models in a field setting not available elsewhere in the U.S. The protocols and models will then be applied to calculate a series of TMDLs for contaminants of concern (e.g. sediment, nutrients and pathogens). These protocols can be used by the EPA Regions, Office of Water, and States to meet the national requirements for TMDL development and implementation under the Clean Water Act. The field study will establish scientific basis for clean sediment and pollutant TMDLs.
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| PUBLISHED REPORT |
Analysis of Mercury in Vermont and New Hampshire Lakes: Evaluation of the Regional Mercury Cycling Model |
09/30/2004
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Knightes, C. AND R. B. Ambrose Jr. Analysis of Mercury in Vermont and New Hampshire Lakes: Evaluation of the Regional Mercury Cycling Model. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/080 (NTIS PB2005-101438), 2004.
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An evaluation of the Regional Mercury Cycling Model (R-MCM, a steady-state fate and transport model used to simulate mercury concentrations in lakes) is presented based on its application to a series of 91 lakes in Vermont and New Hampshire. Visual and statistical analyses are presented in an effort to investigate both the behavior of the model as well as the model's ability to predict the observed mercury concentrations in the water column, sediments and fish tissue. The sensitivity of the model to certain parameters and processes was also evaluated. A comparison of model trends to the observed trends was made. These investigations provide further insight into the complications and challenges that surround modeling the fate and transport of mercury within a given water body, and understanding the exposure concentrations of mercury in the surrounding ecosystem via mercury bioaccumulation in the aquatic food web (e.g., fish) and its transfer to piscivorous wildlife and humans.
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| PUBLISHED REPORT |
On-Line Tools for Assessing Petroleum Releases |
09/30/2004
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Weaver, J. W. On-Line Tools for Assessing Petroleum Releases. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/101 (NTIS PB2005-101442), 2004.
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The Internet tools described in this report provide methods and models for evaluation of contaminated sites. Two problems are addressed by models. The first is the placement of wells for correct delineation of contaminant plumes. Because aquifer recharge can displace plumes downward, the vertical placement of well screens is critical to obtain proper characterization data. The second is the use of models where data are limited. In this case some form of uncertainty analysis is necessary to evaluate transport behavior. The remainder of the report describes a series of tools for estimating various model input parameters.
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| PUBLISHED REPORT |
Comparison of Hydrologic Responses at Different Watershed Scales |
09/30/2004
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Mohamoud, Y. Comparison of Hydrologic Responses at Different Watershed Scales. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/103 (NTIS PB2005-101439), 2004.
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Land surface hydrology controls runoff production and the associated transport of sediments, and a wide variety of anthropogenic organic chemicals, and nutrients from upland landscape areas and hillslopes to streams and other water bodies. Based on interactions between landscape characteristics and precipitation inputs, watersheds respond differently to different climatic inputs (e.g. precipitation and solar radiation). This study compares the hydrologic responses of the Mid-Atlantic watersheds, and identifies the landscape and climatic descriptors that control those responses. Our approach was to select representative watersheds from the Mid-Atlantic region, group the watersheds by physiographic province and ecoregion, and then collect landscape, climate, and hydrologic response descriptor data for each selected watershed. For example, we extracted extensive landscape descriptor data from soil, land use and land cover, and digital elevation model geographic information system (GIS) databases. After sufficient data was collected, we conducted a variety of studies to determine how different landscape and climatic descriptors influence the hydrologic response of Mid-Atlantic watersheds.
This report is comprised of four main parts. Part I describes the selection of the representative study watersheds and the determination of representative physical landscape descriptors for each watershed using geographic information system analysis tools. Part II characterizes the climate and associated hydrologic responses of the study watersheds. To select climate descriptors that are good predictors of hydrologic response, we examined a large number of candidate descriptors. Based on our examination, we selected dryness index and mean monthly rainfall as the best hydrologic response predictors. In Part II, we also present the results of our study hydrologic response comparisons of the study watersheds using a water balance approach. The water balance approach was based on comparisons of precipitation, streamflow, and evapotranspiration at annual, monthly, and daily time scales. These comparisons revealed that elevation and latitudinal position strongly influence hydrologic response. The results also showed that mountainous watersheds of the Appalachian Plateau, Ridge and Valley, and Blue Ridge Physiographic Provinces have more streamflow and less evapotranspiration than watersheds located in the Piedmont Province, and that snowmelt contributes a large portion of streamflow. Part III presents relationships we derived between landscape-climatic descriptors and the hydrologic response descriptors. Flow duration indices (Q1...Q95) were used to represent the hydrologic responses of the study watersheds. In Part III, we also present comparisons of the hydrologic responses of the study watersheds at high flow condition, represented by the Q1 index, medium flow condition represented by the Q50 index, and low flow condition represented by the Q95 index. These comparisons revealed that: the Appalachian Plateau, ridge-dominated Ridge and Valley, and Blue Ridge watersheds have the highest Q1 and Q50 indices; the valley-dominated Ridge and Valley watersheds have the lowest Q50 index, and the Piedmont watersheds have the lowest Q1 index and a relatively high Q95 index. Finally, Part IV discusses some of the implications of the study results for watershed management. We also present applications of the research for hydrologic modeling and watershed assessment.
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| PUBLISHED REPORT |
Population Models for Stream Fish Response to Habitat and Hydrologic Alteration: the Cvi Watershed Tool |
09/30/2004
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Rashleigh, B., M. C. Barber, M. Cyterski, J. M. Johnston, R. S. Parmar, AND Y. Mohamoud. Population Models for Stream Fish Response to Habitat and Hydrologic Alteration: the Cvi Watershed Tool. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/190 (NTIS PB2005-101440), 2004.
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The Canaan Valley Institute (CVI) is dedicated to addressing the environmental problems in the Mid-Atlantic Highlands (MAH). Their goal is to develop and implement solutions to restore damaged areas and protect aquatic systems. In most wadeable streams of the Mid-Atlantic Highlands region of the eastern United States, habitat alteration resulting from agriculture and development is the primary stressor for fish communities. Sedimentation is the primary source of habitat degradation in Highlands streams, and productive, sustainable fisheries, i.e., trophy trout streams, are the valued aquatic endpoints. Planned restoration activities in the region include riparian zone restoration and stream channel design to mitigate near stream inputs and stabilize streambanks. Natural Stream Channel Design (NSCD) is also being investigated by CVI for further optimization of instream habitats for fish communities. Models that predict the responses of fish populations and communities to key habitat characteristics are necessary for CVI's watershed management goals, both for determining where to restore and how, as well as evaluating the most probable outcome of various alternatives. The USEPA National Exposure Research Laboratory (NERL) has developed a suite of modeling tools to be used for this purpose. The CVI Watershed Health Assessment Tool Investigating Fisheries, WHAT IF, contains four components: 1) a Hydrology Tool for predicting hydrologic characteristics of new streams of interest; 2) a Clustering Tool for assigning the most probable fish assemblages to unsampled Mid-Atlantic Highlands streams, 3) a Habitat Suitability Calculator, which evaluates habitat suitability of streams to support fish species and families, and 4) the Bioaccumulation and Aquatic System Simulator (BASS) model, a generalized aquatic ecosystem model that simulates fish community dynamics with time, which permits the evaluation of comparative risk regarding instream restoration combined with fisheries management. The USEPA Environmental Monitoring and Assessment Program (EMAP) surface water dataset (available online, two index periods in the 1990's) is the basis of the habitat associations derived for fish species and communities. Additionally, a tutorial is provided for the user to examine existing scenarios for fish stocking, harvest and restoration combined. Stakeholders interact with the software interface to frame the problem by: selecting valued endpoints of concern and analytical methods, accessing data and models to establish the causal relationships between stream habitat characteristics and changes in endpoint status/trend, and performing multiple model executions and visualizations of projected outcomes to span the range of various management scenarios that might be taken so that associated costs and benefits can be evaluated.
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| PUBLISHED REPORT |
Characteristics of Spilled Oils, Fuels, and Petroleum Products: 2a. Dispersant Effectiveness Data for a Suite of Environmental Conditions the Effects of Temperature, Volatilization, and Energy |
11/09/2004
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Sorial, G. A., S. Chandrasekar, AND J. W. Weaver. Characteristics of Spilled Oils, Fuels, and Petroleum Products: 2a. Dispersant Effectiveness Data for a Suite of Environmental Conditions the Effects of Temperature, Volatilization, and Energy. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/119 (NTIS PB2005-101443), 2004.
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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 between spilled oils, dispersants and the sea, an empirical approach to characterizing the interaction between the dispersant and oil slick may provide a useful or practical approach for including dispersant action in a model. The main objective of this research is 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 are intended to give an indication of the amount of dispersal of these oils under certain conditions.
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| PUBLISHED REPORT |
Characteristics of Spilled Oils, Fuels, and Petroleum Products: 3a. Simulation of Oil Spills and Dispersants Under Conditions of Uncertainty |
09/30/2004
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Weaver, J. W. Characteristics of Spilled Oils, Fuels, and Petroleum Products: 3a. Simulation of Oil Spills and Dispersants Under Conditions of Uncertainty. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/120 (NTIS PB2005-101444), 2004.
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At the request of the US EPA Oil Program Center, ERD is developing an oil spill model that focuses on fate and transport of oil components under various response scenarios. This model includes various simulation options, including the use of chemical dispersing agents on oil slicks. The dispersant simulation is backed by empirical data on the effectiveness of dispersants and oil composition and properties. The model is offered as a tool for oil spill response and planning.
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