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U.S. Environmental Protection Agency (u.s + environmental_protection_agency)
Selected AbstractsDissolved fraction of standard laboratory cladoceran food alters toxicity of waterborne silver to Ceriodaphnia dubia,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Jason M. Kolts Abstract The biotic ligand model (BLM) for the acute toxicity of cationic metals to aquatic organisms incorporates the toxicity-modifying effects of dissolved organic matter (DOM), but the default parameterization (i.e., assuming 10% of DOM is humic acid) does not differentiate DOM from different sources. We exposed a cladoceran (Ceriodaphnia dubia) to Ag in the presence of DOM from filtered YCT (standard yeast,Cerophyll®,trout chow food recommended by the U.S. Environmental Protection Agency [EPA] for cladocerans), from the Suwannee River (GA, USA; relatively little anthropogenic input), and from the Desjardins Canal in Hamilton (ON, Canada; receives treated municipal wastewater effluent). In all three treatments, the dissolved organic carbon (DOC) concentration was 2 mg/L (the concentration following addition of YCT slurry at the U.S. EPA,recommended volume ratio). The average 48-h median effects concentration (EC50) ratios for dissolved Ag in the presence and absence of DOM [i.e., (EC50 with DOM)/(EC50 without DOM)] were as follows: Suwannee River, 1.6; Desjardins Canal, 2.2; and YCT filtrate, 26.8. Therefore, YCT filtrate provided much more protection against Ag toxicity than that provided by DOM from the surface waters. The major spectral characteristic that differentiated YCT filtrate from the other two types of DOM was a strong tryptophan peak in the excitation,emission matrix for YCT. These results have important implications for interpreting Ag toxicity tests in which organisms are fed YCT, and they suggest BLM-calculated toxicity predictions might be improved by incorporating specific chemical constituents or surrogate indices of DOM. Another component of the protective effect against Ag toxicity, however, might be that the dissolved fraction of YCT served as an energy and/or nutrient source for C. dubia. [source] Chronic toxicity of lead to three freshwater invertebrates,Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Martin Grosell Abstract Chronic lead (Pb) toxicity tests with Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalis were performed in artificial freshwaters. The no-observable-effect concentration (NOEC), lowest-observable-effect concentration (LOEC), and calculated 20% effect concentration (EC20) for the rotifer B. calyciflorus were 194, 284, and 125 ,g dissolved Pb/L, respectively. The midge C. tentans was less sensitive, with NOEC and LOEC of 109 and 497 ,g dissolved Pb/L, respectively, and the snail L. stagnalis exhibited extreme sensitivity, evident by NOEC, LOEC, and EC20 of 12, 16, and <4 ,g dissolved Pb/L, respectively. Our findings are presented in the context of other reports on chronic Pb toxicity in freshwater organisms. The L. stagnalis results are in agreement with a previous report on pulmonate snails and should be viewed in the context of current U.S. Environmental Protection Agency (U.S. EPA) hardness adjusted water quality criteria of 8 ,g Pb/L. The present findings and earlier reports indicate that freshwater pulmonate snails may not be protected by current regulatory standards. Measurements of whole-snail Na+ and Ca2+ concentrations following chronic Pb exposure revealed that Na+ homeostasis is disturbed by Pb exposure in juvenile snails in a complicated pattern, suggesting two physiological modes of action depending on the Pb exposure concentration. Substantially reduced growth in the snails that exhibit very high Ca2+ requirements may be related to reduced Ca2+ uptake and thereby reduced shell formation. [source] An evaluation of logistic regression models for predicting amphipod toxicity from sediment chemistryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2005Jeffrey D. Wetherington Abstract An empirical screening level approach was developed to assess the probability of toxicity to benthic organisms associated with contaminated sediment exposure. The study was based on simple logistic regression models (LRMs) of matching sediment chemistry and toxicity data retrieved from a large database of field-collected sediment samples contaminated with multiple chemicals. Three decisions were made to simplify the application of LRMs to sediment samples contaminated with multiple chemicals. First, percent mortality information associated with each sediment sample was condensed into a dichotomous response (i.e., toxic or nontoxic). Second, each LRM assumed that toxicity was attributable to a single contaminant. Third, individual contaminants present at low concentrations were excluded from toxic sediment samples. Based on an analysis of the National Sediment Inventory database, the LRM approach classified 55% of nontoxic sediments as toxic (i.e., false-positives). Because this approach has been used to assess the probability of benthic toxicity as reported by the U.S. Environmental Protection Agency (U.S. EPA), the resultant estimates of potential toxicity convey a misleading impression of the increased hazard that sediments pose to the health of aquatic organisms at many sites in the United States. This could result in important resources needlessly being diverted from truly contaminated sites to evaluate and possibly remediate sediments at uncontaminated sites. [source] Use of laboratory toxicity tests with bivalve and echinoderm embryos to evaluate the bioavailability of copper in San Diego Bay, California, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2005Gunther Rosen Abstract Copper concentrations in parts of San Diego Bay (CA, USA) exceed ambient water quality criteria (WQC; currently 3.1 ,g/L dissolved, U.S. Environmental Protection Agency [U.S. EPA]). In order to better understand the bioavailability of copper to water-column organisms in the bay, toxicity tests were performed with copper added to surface water collected from various sites in the estuary over a three-year period. The species and endpoints used, bivalve and echinoderm embryo-larval development, are among the most sensitive in the U.S. EPA's national toxicity dataset, which is used to derive WQC. No toxicity was observed in ambient bay water samples, as indicated by high proportions of normally developed larvae in control treatments, averaging 93 ± 5% across all sites and all sampling events. Median effects concentrations (EC50), obtained by copper spiking of ambient water samples, ranged from 1.7 to 3.4 times lower at sites located near the mouth compared to sites near the back of the bay. These data indicate a gradient in complexation capacity increasing from the mouth to the back of the bay, which is consistent with similar trends in dissolved organic carbon and total suspended solids. For the bay as a whole, estimates for total recoverable and dissolved water-effect ratios (WER) ranged from 2.07 to 2.27 and 1.54 to 1.67, respectively. Water-effect ratios of this magnitude suggest that adoption of a somewhat higher site-specific WQC for San Diego Bay still would achieve the level of protection that is intended by the WQC guidelines. [source] Quantitative structure-activity relationships for predicting potential ecological hazard of organic chemicals for use in regulatory risk assessmentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2003Mike H. I. Comber Abstract The use of quantitative structure-activity relationships (QSARs) for deriving the predicted no-effect concentration of discrete organic chemicals for the purposes of conducting a regulatory risk assessment in Europe and the United States is described. In the United States, under the Toxic Substances Control Act (TSCA), the TSCA Interagency Testing Committee and the U.S. Environmental Protection Agency (U.S. EPA) use SARs to estimate the hazards of existing and new chemicals. Within the Existing Substances Regulation in Europe, QSARs may be used for data evaluation, test strategy indications, and the identification and filling of data gaps. To illustrate where and when QSARs may be useful and when their use is more problematic, an example, methyl tertiary-butyl ether (MTBE), is given and the predicted and experimental data are compared. Improvements needed for new QSARs and tools for developing and using QSARs are discussed. [source] Response of macroinvertebrates to copper and zinc in a stream mesocosmENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Christopher W Hickey Abstract Metal pollution of streams and rivers is recognized as one of the major concerns for management of freshwaters. Macroinvertebrate communities were established within 12 artificial streams and exposed to three replicated concentrations of a metals mixture (copper and zinc) for 34 d. The cumulative criterion units (CCU = ,[metals]/hardness-adjusted U.S. Environmental Protection Agency [U.S. EPA] 1996 chronic criterion value) of total metals in the low, medium, and high treatments were 2.4, 5.9, and 18 CCUs. Zinc comprised approximately 75% of the CCUs in each of the treatments. Effects on taxa richness and the number of taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT) were moderate at the high exposure concentration (,23% and ,26% respectively, p < 0.05). All of the five major mayfly species showed near extinction, whereas four of the seven caddisflies showed stimulation (up to +121%) and three were reduced (up to ,76%). Redundancy analysis for this metal gradient indicated that 94% of the variance in community structure was explained by three quantitative variables: total mayfly abundance, a mollusk (Potamopyrgus antipodarum) abundance, and the number of EPT individuals, indicating that multiple indices do provide improved predictors of metal stress. Most species showed a threshold response relationship, whereas some community indicators showed apparent hormetic responses (e.g., number of mayfly taxa, total taxa, and number of EPT taxa). Model concentration-response relationships with generalized linear models were used to provide threshold of 20% effective concentration values for species and community metrics. Threshold effect values ranged upwards of 1.4 CCUs, indicating that U.S.EPA chronic criteria would be protective of species and community responses. [source] Implication of polymer toxicity in a municipal wastewater effluentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000Carolyn D. Rowland Abstract The use of cationic polymers as flocculants and coagulant aids to control suspended solid levels in the water and wastewater treatment industry is widespread in most developed countries. Today, the most frequently used clarification polymers, polyacrylamides, are often proprietary, and little information exists on the ecological impacts of these products. Following standard U.S. Environmental Protection Agency (U.S. EPA) whole effluent toxicity testing (WET) protocols, effluent toxicity can be detected via organism response, yet methods to positively characterize cationic polymers in effluents are not provided in U.S. EPA Phase I toxicity identification evaluation (TIE) protocols. Implication of cationic polymer toxicity in a municipal wastewater effluent was achieved through a series of Ceriodaphnia dubia toxicity testing with toxicant elimination steps that included extensive effluent characterization and effluent manipulation. Key in the identification was a discrepancy in effluent toxicity with respect to the type of container in which the effluents were stored. All effluent toxicity was lost within 48 h of storage in plastic containers, while on the contrary, effluent toxicity persisted in glass-contained samples for up to 4 weeks of 4°C storage. A weight-of-evidence approach suggested that the cationic polyacrilamide polymer, Hyperfloc®, was the primary source of acute toxicity in the effluent. Removal of this polymer significantly reduced effluent toxicity. This study suggests that cationic polymer-related toxicity might not be detected if effluent samples are stored in plastic containers. [source] Ecological research in the office of research and development at the U.S. Environmental Protection Agency: An overview of new directions,,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2000Rick A. Linthurst Abstract In virtually every major environmental act, Congress has required that the U.S. Environmental Protection Agency (U.S. EPA) ensure not only that the air be safe to breathe, the water safe to drink, and the food supply free of contamination, but also that the environment be protected. In response, the U.S. EPA's Office of Research and Development (ORD) has established research to improve ecosystem risk assessment and management, identifying it as one of the highest priority research areas for investment over the next 10 years. The research is intended to provide environmental managers with new tools and flexible guidance that reflect a holistic environmental management perspective of science and that can be applied both to common and unique problems. In keeping with its responsibility to provide the U.S. EPA with science that supports a dynamic changing regulatory agenda, the ORD has set the goal of its Ecological Research Program to "provide the scientific understanding required to measure, model, maintain and/or restore, at multiple scales, the integrity and sustainability of ecosystems now, and in the future." In the context of this program, ecological integrity is defined in relative terms as the maintenance of ecosystem structure and function characteristic of a reference condition deemed appropriate for its use by society, and sustainability is defined as the ability of an ecosystem to maintain relative ecological integrity into the future. Therefore, the research program will emphasize relative risk and consider the impact of multiple stressors, at multiple scales and at multiple levels of biological organization. The program will also shift from chemical to biological and physical stressors to a far greater extent than in the past. The purpose of this paper is to provide an introduction to the U.S. EPA's changing ecological research program. [source] A class of nonseparable and nonstationary spatial temporal covariance functionsENVIRONMETRICS, Issue 5 2008Montserrat Fuentes Abstract Spectral methods are powerful tools to study and model the dependency structure of spatial temporal processes. However, standard spectral approaches as well as geostatistical methods assume separability and stationarity of the covariance function; these can be very unrealistic assumptions in many settings. In this work, we introduce a general and flexible parametric class of spatial temporal covariance models, that allows for lack of stationarity and separability by using a spectral representation of the process. This new class of covariance models has a unique parameter that indicates the strength of the interaction between the spatial and temporal components; it has the separable covariance model as a particular case. We introduce an application with ambient ozone air pollution data provided by the U.S. Environmental Protection Agency (U.S. EPA). Copyright © 2007 John Wiley & Sons, Ltd. [source] Regulation of Injected Ground Water TracersGROUND WATER, Issue 4 2000Skelly A. Holmbeck-Pelham Ground water tracer tests are routinely performed to estimate aquifer flow and transport properties, including the determination of well capture zones, hydrogeologic parameters, and contaminant travel times. Investigators may be unaware of tracer test reporting requirements and may fail to notify their regulatory agency prior to conducting tracer tests. The injection of tracers falls under the jurisdiction of the federal Underground Injection Control (UIC) program, which regulates the introduction of substances into underground sources of drinking water as part of the Safe Drinking Water Act. The UIC program is administered by the U.S. Environmental Protection Agency (EPA) and by states with EPA-approved programs. The federal UIC program requires that tracer tests must not endanger underground sources of drinking water, and all tracer tests must be reported prior to injection. We contacted the UIC program administrator for every state in early 1997. Some states report having more stringent requirements, while some states do not meet minimum federal requirements. Although the primary responsibility for ground water tracer selection and use rests on the investigator, national guidance is required to assure compliance with the UIC program. To assist investigators, we present acceptable tracers that have been identified by two states, Nevada and South Carolina, that require no further regulatory review. [source] Mercury Accumulation in Periphyton of Eight River Ecosystems,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2007Amanda H. Bell Abstract:, In 2003, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface-sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r2 = 0.88, in log-log space). Mean MeHg and THg concentrations in surface-sediment periphyton were significantly higher (1,333 ng/m2 for MeHg and 53,980 ng/m2 for THg) than cobble (64 ng/m2 for MeHg and 1,192 ng/m2 for THg) or woody snag (71 ng/m2 for MeHg and 1,089 ng/m2 for THg) periphyton. Concentrations of THg in surface-sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface-sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems. [source] Developing Nutrient Criteria for Streams: An Evaluation of the Frequency Distribution Method,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2007Michael W. Suplee Abstract:, The U.S. Environmental Protection Agency recommends two statistical methods to States and Tribes for developing nutrient criteria. One establishes a criterion as the 75th percentile of a reference-population frequency distribution, the other uses the 25th percentile of a general-population distribution; the U.S. Environmental Protection Agency suggests either method results in similar criteria. To evaluate each method, the Montana Department of Environmental Quality (MT DEQ) assembled data from STORET and other sources to create a nutrient general population. MT DEQ's reference-stream project provided reference population data. Data were partitioned by ecoregions, and by seasons (winter, runoff, and growing) defined for the project. For each ecoregion and season, nutrient concentrations at the 75th percentile of the reference population were matched to their corresponding concentrations in the general population. Additionally, nutrient concentrations from five regional scientific studies were matched to their corresponding reference population concentrations; each study linked nutrients to impacts on water uses. Reference-to-general population matches were highly variable between ecoregions, as nutrients at the 75th percentile of reference corresponded to percentiles ranging from the 4th to the 97th of the general population. In contrast, case studies-to-reference matches were more consistent, matching on average to the 86th percentile of reference, with a coefficient of variation of 13%. [source] Can a federal regulator become a civic enabler?: Watersheds at the U.S. Environmental Protection AgencyNATIONAL CIVIC REVIEW, Issue 3 2006Carmen SirianniArticle first published online: 21 SEP 200 In addition to the works listed in the References, I have drawn on interviews conducted with EPA staff in 2005,2006, as well as with watershed leaders. At the request of some EPA staff, however, I have not named individuals at the agency unless they are clearly identified in published writings or in interviews with watershed leaders. [source] Lessons Learned from Two Decades of Alternative Dispute Resolution Programs and Processes at the U.S. Environmental Protection AgencyPUBLIC ADMINISTRATION REVIEW, Issue 6 2001Rosemary O'Leary Mediation, facilitation, and other alternative dispute resolution (ADR) techniques are being used in federal agencies, state and local governments, private-sector organizations, and among private citizens in an effort to prevent and resolve disputes in a timely, cost-effective, and less adversarial manner. The U.S. Environmental Protection Agency (EPA), one of the pioneers in the application of ADR processes and techniques to public policy disputes, recently announced that it plans to in-crease the use of ADR techniques and practices across all agency programs. This article reports the results of a four-part evaluation of the use of ADR in enforcement actions at the EPA during the last two decades. Funded by the Hewlett Foundation, this effort utilized in-depth telephone interviews, government statistics, and archival records. The four groups interviewed were EPA's alternative dispute resolution specialists, potentially responsible parties (defendants) to EPA enforcement lawsuits, mediators and facilitators to EPA cases, and agency enforcement attorneys who had participated in agency enforcement ADR processes. Concluding that there are generally high levels of satisfaction with the EPA's enforcement ADR program, this article examines the sources of obstacles and assistance to ADR efforts at the EPA, suggests ways in which the EPA might improve its ADR programs, and draws lessons from the EPA's experiences that may be helpful to other public programs or organizations. [source] Sustainable soil remediation by refrigerated condensation at sites with "high-concentration" recalcitrant compounds and NAPL: Two case studiesREMEDIATION, Issue 1 2008Lowell Kessel Remediation of recalcitrant compounds at sites with high concentrations of volatile organic compounds (VOCs) or nonaqueous-phase liquids (NAPLs) can present significant technical and financial (long-term) risk for stakeholders. Until recently, however, sustainability has not been included as a significant factor to be considered in the feasibility and risk evaluation for remediation technologies. The authors present a framework for which sustainability can be incorporated into the remediation selection criteria focusing specifically on off-gas treatment selection for soil vapor extraction (SVE) remediation technology. SVE is generally considered an old and standard approach to in situ remediation of soils at a contaminated site. The focus on off-gas treatment technology selection in this article allows for more in-depth analysis of the feasibility evaluation process and how sustainable practices might influence the process. SVE is more commonly employed for recovery of VOCs from soils than other technologies and generally employs granular activated carbon (GAC), catalytic, or thermal oxidation, or an emerging alternative technology known as cryogenic-compression and condensation combined with regenerative adsorption (C3,Technology). Of particular challenge to the off-gas treatment selection process is the potential variety of chemical constituents and concentrations changing over time. Guidance is available regarding selection of off-gas treatment technology (Air Force Center for Environmental Excellence, 1996; U.S. Environmental Protection Agency, 2006). However, there are common shortcomings of off-gas treatment technology guidance and applications; practitioners have rarely considered sustainability and environmental impact of off-gas treatment technology selection. This evaluation includes consideration of environmental sustainability in the selection of off-gas treatment technologies and a region-specific (Los Angeles, California) cost per pound and time of remediation comparisons between GAC, thermal oxidation, and C3,Technology. © 2008 Wiley Periodicals, Inc. [source] Evapotranspiration covers: An innovative approach to remediate and close contaminated sitesREMEDIATION, Issue 1 2003Kelly L. Madalinski A new, cost-effective option for the remediation and final closure of contaminated landfill sites gaining interest among environmental professionals is the evapotranspiration (ET) cover. Unlike current covers that use hydraulic barriers to prevent water from reaching the waste, ET covers rely on the simple concept of using water balance components to meet this goal. Depending on site conditions and other factors, ET covers may be less costly to construct, while still offering performance equivalent to conventional covers. While ET covers are being proposed, tested, or installed at a number of contaminated sites, field performance data remain limited. To address the need for more information, the U.S. Environmental Protection Agency (EPA) has been conducting several efforts to make available more information about this promising alternative solution. This article summarizes these efforts and provides information on the current status of using ET covers at contaminated sites. © 2003 Wiley Periodicals, Inc. [source] Characterizing a Brownfields recreational reuse scenario using the Triad Approach,Assunpink Creek Greenways projectREMEDIATION, Issue 4 2003James Mack Since the early 1990s the U.S. government has been developing and implementing public policies that advance the redevelopment of brownfields, and the recent passage of the Small Business Liability Relief and Brownfields Revitalization Act (SBLRBRA) will significantly advance efforts to integrate environmental contamination mitigation and redevelopment. Experience has demonstrated that successful redevelopment requires the collection, analysis, and interpretation of environmental data in a timely and cost-effective manner in order to allow developers and lenders to efficiently use cleanup resources, develop response strategies that integrate cleanup with redevelopment, and support meaningful outreach to involved stakeholders. Recent advances in the science and technology of site characterization hold the promise of improved site characterization outcomes while saving time and money. One such advancement, the Triad Approach, combines systematic up-front planning with the use of a dynamic field investigation process and the generation of real time data to allow in-field decision making on sample location selection. This article describes an application of the Triad Approach to redevelopment of an urban greenway in Trenton, New Jersey. The Triad Approach, initiated through a partnership between the City of Trenton, New Jersey Department of Environmental Protection, New Jersey Institute of Technology, and the U.S. Environmental Protection Agency, demonstrated that this approach could accelerate the characterization of the 60-acre, 11-parcel project area. Environmental issues that were solved using the Triad Approach included the delineation of the extent of historic fill, determination of no further action for several areas of concern, detailed investigation of specific impacted areas and the acquisition of sufficient data to allow the city to make important decisions regarding remediation costs and property acquisition. © 2003 Wiley Periodicals, Inc. [source] Treatment of Highly Contaminated Groundwater: A SITE Demonstration ProjectREMEDIATION, Issue 3 2001Daniel Sullivan From September through November 1994, the U.S. Environmental Protection Agency (EPA) conducted a field demonstration of the remediation of highly contaminated groundwater at the Nascolite Superfund site located in Millville, New Jersey. Besides high concentrations of the major contaminant, methyl methacrylate (MMA), the groundwater also contained small amounts of volatile and semivolatile organic compounds. ZenoGem® technology, an integrated bioreactor and ultrafiltration membrane system, was employed for this demonstration project. Approximately 30,000 gallons of groundwater containing MMA in concentrations of 567 to 9,500 milligrams per liter (mg/L) and chemical oxygen demand (COD) values ranging from 1,490 to 19,600 mg/L was treated. The demonstration focused on the system's ability to remove MMA and reduce COD from the groundwater. Results of the three-month demonstration showed that average MMA and COD removal efficiencies were greater than 99.9 and 86.9, respectively. The total cost of treatment, depending on the duration of the project, is estimated to vary from $0.22 to $0.55 (in 1994 dollars) per gallon of groundwater treated. © 2001 John Wiley & Sons. [source] Analytical, Risk Assessment, and Remedial Implications Due to the Co-Presence of Polychlorinated Biphenyls and Terphenyls at Inactive Hazardous Waste SitesREMEDIATION, Issue 1 2000James J. Pagano Investigations conducted at three inactive hazardous waste sites in New York State have confirmed the co-presence of polychlorinated hiphenyls (PCBs) and polychlorinated terphenyls (PCTs) in soils, sediments, and biota. The PCTs at all three sites were positively identified as Aroclor 5432, with the most probable source being the hydraulic fluid Pydraul 312A utilized for high-temperature applications. The identification of the lower-chlorinated PCT formulations in environmental samples is problematical, since PCT Aroclors 5432 and 5442 are not chromatographically distinct from the higher-chlorinated (PCB) Aroclors 1254, 1260, 1262, and 1268 using conventional gas chromatography,electron capture detection. Results from this study indicate that U.S. Environmental Protection Agency (USEPA) approved PCB methods routinely utilized by most commercial laboratories based on Florisil adsorption column chromatography cleanup are inadequate to produce valid chromatographic separation and quantitative results with soils, sediment, and biota samples containing both PCBs and PCTs. The presence of co-eluting PCBs and PCTs precludes accurate quantitation due to significant differences in PCB/PCT electron capture detector response factors, and the potential for misidentification of PCT Aroclors as higher chlorinated PCB Aroclors. A method based on alumina column adsorption chromatography was used, allowing for the accurate identification and quantitation of PCB and PCT Aroclors. The results of this study suggest that the utilization of alumina adsorption column separation may have applicability and regulatory significance to other industrially contaminated sites which historically used Pydraul 312A. Inferences. [source] Measured partitioning coefficients for parent and alkyl polycyclic aromatic hydrocarbons in 114 historically contaminated sediments: Part 1.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006KOC values Abstract Polycyclic aromatic hydrocarbon (PAH) partitioning coefficients between sediment organic carbon and water (KOC) values were determined using 114 historically contaminated and background sediments collected from eight different rural and urban waterways in the northeastern United States. More than 2,100 individual KC values were measured in quadruplicate for PAHs ranging from two to six rings, along with the first reported KOC values for alkyl PAHs included in the U.S. Environmental Protection Agency's (U.S. EPA) sediment narcosis model for the prediction of PAH toxicity to benthic organisms. Sediment PAH concentrations ranged from 0.2 to 8,600 ,g/g (U.S. EPA 16 parent PAHs), but no observable trends in KOC values with concentration were observed for any of the individual PAHs. Literature KOC values that are commonly used for environmental modeling are similar to the lowest measured values for a particular PAH, with actual measured values typically ranging up to two orders of magnitude higher for both background and contaminated sediments. For example, the median log KOC values we determined for naphthalene, pyrene, and benzo[a]pyrene were 4.3, 5.8, and 6.7, respectively, compared to typical literature KOC values for the same PAHs of 2.9, 4.8, and 5.8, respectively. Our results clearly demonstrate that the common practice of using PAH KOC values derived from spiked sediments and modeled values based on n -octanol,water coefficients can greatly overestimate the actual partitioning of PAHs into water from field sediments. [source] Treatment technologies for mercury in soil, waste, and waterREMEDIATION, Issue 1 2007Martha Otto Mercury occurs naturally in the environment and can be found in elemental (metallic), inorganic, and organic forms. Modern uses for mercury include chemical manufacturing, thermometers, and lighting (mercury vapor and fluorescent lamps). The chemical and allied products industry group is responsible for the largest quantity of mercury used in the United States. Mercury, particularly the organic methylmercury form, is a potent neurotoxin capable of impairing neurological development in fetuses and young children and of damaging the central nervous system of adults. Mercury regulations span multiple federal and state environmental statutes, as well as multiple agency jurisdictions. In August 2007, the U.S. Environmental Protection Agency's (US EPA's) Office of Superfund Remediation and Technology Innovation (OSRTI) published a report titled "Treatment Technologies for Mercury in Soil, Waste, and Water." The report identifies eight treatment technologies and 57 projects, 50 of which provide performance data. This information can help managers at sites with mercury-contaminated media and generators of mercury-contaminated waste and wastewater to identify proven and effective mercury treatment technologies; screen technologies based on application-specific goals, characteristics, and costs; and apply experiences from sites with similar treatment challenges. This article provides a synopsis of the US EPA report, which is available at http://clu-in.org/542R07003. © 2007 Wiley Periodicals, Inc., [source] Steady-state field-scale gas permeability estimation and pore-gas velocity calculation in a domain open to the atmosphereREMEDIATION, Issue 4 2000Dominic C. Digiulio Field-scale estimation of gas permeability and subsequent computation of pore-gas velocity profiles are critical elements of sound soil venting design. It has been our experience, however, in U.S. Environmental Protection Agency's (EPA's) technical assistance program, provided by the Office of Research and Development in support EPA regional offices, that many venting practitioners are unaware of equations and data interpretation methods appropriate for gas permeability estimation and pore-gas velocity computation. To ameliorate this situation, we use data collected at a U.S. Coast Guard Station in Traverse City, Michigan, to demonstrate gets permeability estimation and pore-gas velocity calculation for steady-state, axisymmetric, two-dimensional gas flow in a domain open to the atmosphere. For gas permeability estimation, we use random guesses constrained with decreasing intervals of radial and vertical permeabilityand analysis of root mean square errors to ensure attainment of a global versus local minimum. We demonstrate confidence in permeability estimation by providing plots of observed versus simulated pressure response. Finally, we illustrate how plots of pore-gas velocity as a function of distance and flow rate can be helpful in venting design. [source] | |||||||||||||