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- Bob is an environmental scientist with over 20 years of experience in environmental and aquatic chemistry, EPA regula... moreBob is an environmental scientist with over 20 years of experience in environmental and aquatic chemistry, EPA regulatory issues, site-specific criteria, water quality modeling, and chemical modeling. His recent work has focused on developing mechanistic models to explain and predict the bioavailability and toxicity of metals in the environment. This work has included the development of the Biotic Ligand Model (BLM), which has been used by EPA as the basis for the ambient water quality criteria for copper. Bob has led efforts in developing BLM versions for a variety of metals and environmental media, for both freshwater and marine environments. These efforts have resulted in a number of software packages that provide easy-to-use approaches to assess metal bioavailability when setting site-specific water quality criteria and assessing ecological risk associated with metals in the environment.edit
Dissolved organic carbon (DOC) is known to ameliorate the toxicity of the trace metal nickel (Ni) to aquatic animals. In theory, this effect is mediated by the capacity of DOC to bind Ni, rendering it less bioavailable, with the resulting... more
Dissolved organic carbon (DOC) is known to ameliorate the toxicity of the trace metal nickel (Ni) to aquatic animals. In theory, this effect is mediated by the capacity of DOC to bind Ni, rendering it less bioavailable, with the resulting reduction in accumulation limiting toxicological effects. However, there is a lack of experimental data examining Ni accumulation in marine settings with natural sources of DOC. In the current study, radiolabelled Ni was used to examine the time- and concentration-dependence of Ni accumulation, using naturally sourced DOC on developing larvae of the sea urchin Strongylocentrotus purpuratus. Contrary to prediction, the two tested natural DOC samples (collected from the eastern United States, DOC 2 (Seaview park, Rhode Island (SVP)) and DOC 7 (Aubudon Coastal Center, Connecticut)) which had previously been shown to protect against Ni toxicity, did not limit accumulation. The control (artificial seawater with no added DOC), and the DOC 2 sample could mostly be described as having saturable Ni uptake, whereas Ni uptake in the presence of DOC 7 was mostly linear. These data provide evidence that DOC modifies the bioavailability of Ni, through either indirect effects (e.g. membrane permeability) or by the absorption of DOC-Ni complexes. There was some evidence for regulation of Ni accumulation in later-stage embryos (96-h) where the bioconcentration factor for Ni declined with increasing Ni exposure concentration. These data have implications for predictive modelling approaches that rely on known relationships between Ni speciation, bioavailability and bioreactivity, by suggesting that these relationships may not hold for natural marine DOC samples in the developing sea urchin model system.
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Research Interests: Computer Science, Biochemical Engineering, Speciation, Bioaccumulation, Health, and 12 moreEnvironmental Chemistry, Medicine, Earth and Environmental Sciences, Biological Sciences, Environmental Sciences, Dissolved organic matter, Bioavailability, CHEMICAL SCIENCES, Biotic ligand model, Technology and Engineering, Environmental Toxicology and Chemistry, and water quality criteria
The biotic ligand model (BLM) was developed to explain and predict the effects of water chemistry on the acute toxicity of metals to aquatic organisms. The biotic ligand is defined as a specific receptor within an organism where metal... more
The biotic ligand model (BLM) was developed to explain and predict the effects of water chemistry on the acute toxicity of metals to aquatic organisms. The biotic ligand is defined as a specific receptor within an organism where metal complexation leads to acute toxicity. The BLM is designed to predict metal interactions at the biotic ligand within the context of aqueous metal speciation and competitive binding of protective cations such as calcium. Toxicity is defined as accumulation of metal at the biotic ligand at or above a critical threshold concentration. This modeling framework provides mechanistic explanations for the observed effects of aqueous ligands, such as natural organic matter, and water hardness on metal toxicity. In this paper, the development of a copper version of the BLM is described. The calibrated model is then used to calculate LC50 (the lethal concentration for 50% of test organisms) and is evaluated by comparison with published toxicity data sets for freshwater fish (fathead minnow, Pimephales promelas) and Daphnia.
Research Interests: Chemistry, Crustacea, Environmental Chemistry, Daphnia, Biological Sciences, and 15 moreEnvironmental Sciences, Copper, Animals, Bioavailability, CHEMICAL SCIENCES, Biotic ligand model, Cladocera, Dissolved Organic Carbon, Daphnia Magna, Environmental Toxicology and Chemistry, Cyprinidae, Acute Toxicity, Environmental, Biological Availability, and copper toxicity
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Research Interests: Chemistry, Crustacea, Environmental Chemistry, Daphnia, Biological Sciences, and 15 moreEnvironmental Sciences, Copper, Animals, Bioavailability, CHEMICAL SCIENCES, Biotic ligand model, Cladocera, Dissolved Organic Carbon, Daphnia Magna, Environmental Toxicology and Chemistry, Cyprinidae, Acute Toxicity, Environmental, Biological Availability, and copper toxicity
Research Interests: Chemistry, Carbon, Biology, Environmental Chemistry, Rotifera, and 15 moreMedicine, Multidisciplinary, Environmental science and technology, Copper, Salinity, Animals, Confidence intervals, Bioavailability, Theoretical Models, Biotic ligand model, Dissolved Organic Carbon, Ligands, Organic Chemicals, Rotifer, and Brachionus
ABSTRACTA large water quality data set, representing more than 100 surface‐water locations sampled from 2007 to 2017 in the Los Alamos area of New Mexico, USA's Pajarito Plateau, was assembled to evaluate Al concentrations in... more
ABSTRACTA large water quality data set, representing more than 100 surface‐water locations sampled from 2007 to 2017 in the Los Alamos area of New Mexico, USA's Pajarito Plateau, was assembled to evaluate Al concentrations in unfiltered and filtered samples. Aluminum concentrations often exceeded United States Environmental Protection Agency (USEPA) and New Mexico ambient water quality criteria (AWQC), regardless of filter size and sample location. However, AWQC are based on laboratory toxicity studies using soluble Al salts and do not reflect natural conditions in Pajarito Plateau surface waters. The plateau is predominately covered by glassy and recrystallized volcanic ashes (e.g., Bandelier Tuff) containing colloidal to sand‐sized aluminosilicates. Samples from natural background drainages and areas downstream of developed regions exhibited similar Al concentrations, suggesting that AWQC exceedances are caused by naturally elevated Al concentrations. Solubility calculations i...
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Research Interests: Chemistry, Water quality, Aquatic Toxicology, Environmental Chemistry, Medicine, and 11 moreBiological Sciences, Aquatic Ecosystem, Environmental Sciences, Toxicity, Surface Water, Sulfate, Bioavailability, CHEMICAL SCIENCES, Dissolved Organic Carbon, Water Quality, and Environmental Toxicology and Chemistry
The equilibrium partitioning sediment benchmarks (ESBs) derived by the US Environmental Protection Agency (USEPA) in 2005 provide a mechanistic framework for understanding metal bioavailability in sediments by considering equilibrium... more
The equilibrium partitioning sediment benchmarks (ESBs) derived by the US Environmental Protection Agency (USEPA) in 2005 provide a mechanistic framework for understanding metal bioavailability in sediments by considering equilibrium partitioning (EqP) theory, which predicts that metal bioavailability in sediments is determined largely by partitioning to sediment particles. Factors that favor the partitioning of metals to sediment particles, such as the presence of acid volatile sulfide (AVS) and sediment organic matter, reduce metal bioavailability to benthic organisms. Because ESBs link metal bioavailability to partitioning to particles, they also predict that measuring metals in porewater can lead to a more accurate assessment of bioavailability and toxicity to benthic organisms. At the time of their development, sediment ESBs based on the analysis of porewater metal concentrations were limited to comparison with hardness‐dependent metals criteria for the calculation of interstit...
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The US Environmental Protection Agency Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures (Cadmium, Copper, Lead, Nickel, Silver and Zinc)... more
The US Environmental Protection Agency Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures (Cadmium, Copper, Lead, Nickel, Silver and Zinc) equilibrium partitioning approach causally link metal concentrations and toxicological effects; they apply to sediment and porewater (i.e., interstitial water). The evaluation of bioavailable metal concentrations in porewater, using tools such as the biotic ligand model, provides an advancement that complements sediment‐based evaluations. However, porewater characterization is less commonly performed in sediment bioassays than sediment chemistry characterization due to the difficulty and expense of porewater collection as well as concerns about interpretation of porewater data. This study discusses the advantages and disadvantages of different porewater extraction methods for analysis of metals and bioavailability parameters during laboratory sediment bioass...
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In this study a fully linked plant-soil-water model PnET-BGC/CHESS (Santore, R.C., 1996. PnET-BGC/CHESS model. Version P3NC115; Santore, R.C., 1999. Modeling forest soil response to chemical treatment at three sites in the Adirondack... more
In this study a fully linked plant-soil-water model PnET-BGC/CHESS (Santore, R.C., 1996. PnET-BGC/CHESS model. Version P3NC115; Santore, R.C., 1999. Modeling forest soil response to chemical treatment at three sites in the Adirondack Mountains, New York) was evaluated and applied. Forest growth, hydrologic, and biogeochemical processes with emphasis on element cycling in forest and adjacent aquatic ecosystems were simulated for the
Research Interests: Environmental Science, Biogeochemistry, Czech, Multidisciplinary, Ecological Modelling, and 15 moreCzech Republic, Aquatic Ecosystem, Forest soil nutrition, Acidification, Picea abies, Acid Deposition, Norway Spruce, Forest Products, Forest Growth, Forest Soil Ecology, Podzol, Chemical Treatment, Soil Water, Biogeochemical Cycle, and Drainage basin
Research Interests: Biology, Environmental Chemistry, Daphnia, Water Chemistry, Medicine, and 15 moreBiological Sciences, Environmental Sciences, Silver, Animals, North America, CHEMICAL SCIENCES, Validation Studies, Biotic ligand model, Dissolved Organic Carbon, Environmental Toxicology and Chemistry, Cyprinidae, Ionic Strength, Environmental, Ligands, and Ceriodaphnia dubia
Research Interests: Chemistry, Environmental Chemistry, Medicine, Fish Physiology, Biological Sciences, and 15 moreEnvironmental Sciences, Osmoregulation, Animals, Organism, Bioavailability, Biotic ligand model, Metal ion, Metal Toxicity, Acute Toxicity, Oncorhynchus Mykiss, Ligands, Binding Site, Chronic Toxicity, Cumulant, and Medical and Health Sciences
The chemistry, bioavailability, and toxicity of aluminum (Al) in the aquatic environment are complex and affected by a wide range of water quality characteristics (including pH, hardness, and dissolved organic carbon). Data gaps in Al... more
The chemistry, bioavailability, and toxicity of aluminum (Al) in the aquatic environment are complex and affected by a wide range of water quality characteristics (including pH, hardness, and dissolved organic carbon). Data gaps in Al ecotoxicology exist for pH ranges representative of natural surface waters (pH 6–8). To address these gaps, a series of chronic toxicity tests were performed at pH 6 with 8 freshwater species, including 2 fish (Pimephales promelas and Danio rerio), an oligochaete (Aeolosoma sp.), a rotifer (Brachionus calyciflorus), a snail (Lymnaea stagnalis), an amphipod (Hyalella azteca), a midge (Chironomus riparius), and an aquatic plant (Lemna minor). The 10% effect concentrations (EC10s) ranged from 98 μg total Al/L for D. rerio to 2175 μg total Al/L for L. minor. From these data and additional published data, species‐sensitivity distributions (SSDs) were developed to derive concentrations protective of 95% of tested species (i.e., 50% lower confidence limit of a 5th percentile hazard concentration [HC5‐50]). A generic HC5‐50 (not adjusted for bioavailability) of 74.4 μg total Al/L was estimated using the SSD. An Al‐specific biotic ligand model (BLM) was used to develop SSDs normalized for bioavailability based on site‐specific water quality characteristics. Normalized HC5‐50s ranged from 93.7 to 534 μg total Al/L for waters representing a range of European ecoregions, whereas a chronic HC5 calculated using US Environmental Protection Agency aquatic life criteria methods (i.e., a continuous criterion concentration [CCC]) was 125 μg total Al/L when normalized to Lake Superior water in the United States. The HC5‐50 and CCC values for site‐specific waters other than those in the present study can be obtained using the Al BLM. Environ Toxicol Chem 2018;37:36–48. © 2017 SETAC
Research Interests: Biology, Environmental Chemistry, Medicine, Biological Sciences, Aluminum, and 15 moreEnvironmental Sciences, Animals, Bioavailability, CHEMICAL SCIENCES, Biotic ligand model, Aquatic organisms, Fresh water, Water Quality, Environmental Toxicology and Chemistry, Biological Availability, Chronic Toxicity, Lymnaea stagnalis, Chironomus riparius, Reference standards, and Brachionus calyciflorus
Research Interests: Chemistry, Carbon, Environmental Chemistry, Daphnia, Biological Sciences, and 15 moreAluminum, Environmental Sciences, Animals, Hardness, CHEMICAL SCIENCES, Aquatic organisms, Fresh water, Cladocera, Dissolved Organic Carbon, Daphnia Magna, Environmental Toxicology and Chemistry, Cyprinidae, Acute Toxicity, Chlorophyta, and Ceriodaphnia dubia
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US Environmental Protection Agency (USEPA) Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures are based on the principle that metals toxicity to... more
US Environmental Protection Agency (USEPA) Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures are based on the principle that metals toxicity to benthic organisms is determined by bioavailable metals concentrations in porewater. One ESB is based on the difference between simultaneously extracted metal (SEM) and acid volatile sulfide (AVS) concentrations in sediment (excess SEM). The excess SEM ESBs include a lower uncertainty bound, below which most samples (95%) are expected to be “nontoxic” (defined as a bioassay mortality rate ≤24%), and an upper uncertainty bound, above which most samples (95%) are expected to be “toxic” (defined as a mortality rate >24%). Samples that fall between the upper and lower bounds are classified as “uncertain.” Excess SEM ESBs can, in principle, be improved by normalizing for organic carbon (OC). OC is a binding phase that reduces metals bioavailability. OC normalization should improve the accuracy of bioavailable metal concentration estimates, thus tightening uncertainty bounds. We evaluated field‐collected sediments from 13 studies with excess SEM, OC, and bioassay data (n = 740). Use of the OC‐normalized excess SEM benchmarks did not improve prediction accuracy. The ESB model predicts OC‐normalized excess SEM exceeding the upper benchmark even when toxicity is not observed, because error in the OC normalization model increases at low OC concentrations. To minimize the likelihood of incorrectly identifying nontoxic samples as toxic, we recommend that OC normalization of excess SEM should not be considered for sediments with an OC concentration <1% and is questionable for sediments with an OC concentration of 1%–4%. Additional focused studies are needed to confirm or refine the minimum sediment OC concentrations that are applicable for reducing uncertainty in toxicity predictions due to excess SEM. Integr Environ Assess Manag 2022;18:174–186. © 2021 SETAC
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Research Interests: Environmental Science, Water quality, Environmental Chemistry, Daphnia, Medicine, and 15 moreBiological Sciences, Environmental Sciences, Europe, Animals, Surface Water, South America, Bioavailability, North America, CHEMICAL SCIENCES, Biotic ligand model, Fresh water, Daphnia Magna, Water Quality, Integrated, and Biological Availability
Since the mid‐1970s, thousands of studies have evaluated the toxicity of various chemicals to aquatic organisms. Results from many of these studies have been used to develop species sensitivity distributions (SSDs) or genus sensitivity... more
Since the mid‐1970s, thousands of studies have evaluated the toxicity of various chemicals to aquatic organisms. Results from many of these studies have been used to develop species sensitivity distributions (SSDs) or genus sensitivity distributions (GSDs) for deriving water quality guidelines. Recently, there has been more emphasis on evaluating the toxicity of chemicals to sensitive organisms rather than the entire range of sensitivities. The SSD approach is intended to inform the derivation of guidelines for the protection of all species, not just those that were included in the SSD. The overemphasis of the more sensitive end of the SSD can contribute to a skew in the observed distribution such that the shape of the distribution is distorted from what it would be if all species could be tested, which ultimately affects the derived guideline value. The freshwater acute Cu GSD derived by the US Environmental Protection Agency (USEPA) is one that exemplifies this trend, with one‐third of the genera in the GSD belonging to only 3 taxonomic families, all of which are nearer to the sensitive end of the distribution. The stronger representation of the more sensitive families does not seem to mirror the overall abundance of species within those families in nature. This tendency toward testing sensitive organisms is not seen in the chronic Cu SSD. In the present study, Cu toxicity literature is reviewed and long‐term trends in the availability of toxicity information for species of varying sensitivity are examined. As part of the present review, the apparent bias that favors the publication of toxicity data for sensitive taxa is demonstrated, and implications for the representativeness of SSDs and their use in developing water quality guidelines are discussed. Integr Environ Assess Manag 2019;00:000–000. © 2019 SETAC
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Toxicity modifying factors can either be modeled empirically with linear regression models or mechanistically, such as with the Biotic Ligand Model (BLM). The primary factors affecting the toxicity of nickel to aquatic organisms are... more
Toxicity modifying factors can either be modeled empirically with linear regression models or mechanistically, such as with the Biotic Ligand Model (BLM). The primary factors affecting the toxicity of nickel to aquatic organisms are hardness, dissolved organic carbon (DOC), and pH. Interactions between these terms were also considered. This article develops multiple linear regressions (MLRs) with stepwise regression for 5 organisms in acute exposures, 4 organisms in chronic exposures, and pooled models for acute, chronic, and all data, and compares the performance of the Pooled-All MLR model to the performance of the BLM. Independent validation data was used for evaluating model performance, which for pooled models included data for organisms and endpoints not present in the calibration dataset. Hardness and DOC were most often selected as the explanatory variables in the MLR models. An attempt was also made at evaluating the uncertainty of the predictions for each model; predictions that showed the most error tended to show the highest levels of uncertainty as well. The performance of the two models were largely equal, with differences in performance becoming more apparent when looking at the performance within subsets of the data. This article is protected by copyright. All rights reserved.
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In 2007, the Biotic Ligand Model (BLM) became the basis for the US Environmental Protection Agency (USEPA) freshwater water quality criteria (WQC) for Cu. Applying the BLM typically results in time-variable WQC, which are not unique to... more
In 2007, the Biotic Ligand Model (BLM) became the basis for the US Environmental Protection Agency (USEPA) freshwater water quality criteria (WQC) for Cu. Applying the BLM typically results in time-variable WQC, which are not unique to the BLM; they result from any criteria approach that depends on water chemistry (e.g., ammonia criteria or hardness-based equations for metals). However, widespread use of the BLM has renewed interest in developing an approach that considers variability when setting permit limits or benchmarks. To aid in establishing these benchmarks, we developed a fixed monitoring benchmark (FMB) approach: a probability-based method that incorporates time variability in BLM-predicted instantaneous water quality criteria (IWQC) and instream Cu concentrations. The FMB approach provides benchmarks that can be used to simplify implementation of time-variable WQC. Although it appears reasonable to apply this approach to derive a site-specific regulatory limit, the FMB does not technically represent a limit above which aquatic effects are expected. Rather, it represents a fixed concentration intended to yield the same level of protection as time-variable IWQC, which rely upon toxic unit (TU) distribution; each TU is calculated for a single sample using the Cu concentration and IWQC for this sample. The distribution of TUs for a particular site is used to estimate the probability that instream Cu concentrations are below associated IWQC. Our results suggest that Cu variability and corresponding IWQC, and their degree of correlation, indicate the magnitude of the FMB relative to the IWQC distribution. The FMB approach determines a maximum Cu distribution such that the resulting WQC exceedance frequency is consistent with the level of protection that is intended for the applicable water quality standard (WQS). This approach makes use of time-variable BLM-based WQC in regulatory contexts wherein a single benchmark is consistent with past practices and established implementation methods. Integr Environ Assess Manag 2018;14:722-735. © 2018 SETAC.
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The acute toxicity of silver to Ceriodaphnia dubia was investigated in laboratory reconstituted waters as well as in natural waters and reconstituted waters with natural organic matter. The water quality characteristics of the laboratory... more
The acute toxicity of silver to Ceriodaphnia dubia was investigated in laboratory reconstituted waters as well as in natural waters and reconstituted waters with natural organic matter. The water quality characteristics of the laboratory reconstituted waters were systematically varied. The parameters that demonstrated an ability to mitigate the acute toxic effects of silver were chloride, sodium, organic carbon, and chromium reducible sulfide. Factors that did not have a consistent effect on the acute toxicity of silver to C. dubia, at least over the range of conditions tested, included hardness, alkalinity, and pH. The biotic ligand model was calibrated to the observed test results and found to be of use in quantifying the effect of changing water quality characteristics on silver bioavailability and toxicity. The model generally predicted silver toxicity within a factor of two and should be useful in modifying water quality criteria.
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There is concern whether regulatory criteria for copper (Cu) are protective against chemosensory and behavioral impairment in aquatic organisms. We compiled Cu toxicity data for these and other sublethal endpoints in 35 tests with... more
There is concern whether regulatory criteria for copper (Cu) are protective against chemosensory and behavioral impairment in aquatic organisms. We compiled Cu toxicity data for these and other sublethal endpoints in 35 tests with saltwater organisms and compared the Cu toxicity thresholds to biotic ligand model (BLM)-based estimated chronic limits (ECL values, which are EC20 values [20% effect concentrations] for the embryo-larval life stage of the blue mussel [Mytilus edulis]-a sensitive saltwater species to Cu that has historically been used to derive saltwater Cu criteria). Only eight of the 35 tests had sufficient toxicity and chemistry data to support unequivocal conclusions (i.e., a Cu EC20 or no-observed-effect concentration could be derived; and Cu and DOC concentrations were measured [or DOC concentrations could be inferred from the test-water source]). The BLM-based ECL values would have been protective (i.e., the ECL was lower than the toxicity threshold) in seven of tho...
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Aluminum (Al) toxicity to aquatic organisms is strongly affected by water chemistry. Toxicity-modifying factors such as pH, dissolved organic carbon (DOC), hardness, and temperature have a large impact on the bioavailability and toxicity... more
Aluminum (Al) toxicity to aquatic organisms is strongly affected by water chemistry. Toxicity-modifying factors such as pH, dissolved organic carbon (DOC), hardness, and temperature have a large impact on the bioavailability and toxicity of Al to aquatic organisms. The importance of water chemistry on the bioavailability and toxicity of Al suggests that interactions between Al and chemical constituents in exposures to aquatic organisms can affect the form and reactivity of Al, thereby altering the extent to which it interacts with biological membranes. These types of interactions have previously been observed in the toxicity data for other metals, which have been well described by the biotic ligand model (BLM) framework. In BLM applications to other metals (including cadmium, cobalt, copper, lead, nickel, silver, and zinc), these interactions have focused on dissolved metal. A review of Al toxicity data shows that concentrations of Al that cause toxicity are frequently in excess of ...
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The chemistry, bioavailability, and toxicity of aluminum (Al) in the aquatic environment are complex and affected by a wide range of water quality characteristics (including pH, hardness, and dissolved organic carbon). Data gaps in Al... more
The chemistry, bioavailability, and toxicity of aluminum (Al) in the aquatic environment are complex and affected by a wide range of water quality characteristics (including pH, hardness, and dissolved organic carbon). Data gaps in Al ecotoxicology exist for pH ranges representative of natural surface waters (pH 6-8). To address these gaps, a series of chronic toxicity tests were performed at pH 6 with 8 freshwater species, including 2 fish (Pimephales promelas and Danio rerio), an oligochaete (Aeolosoma sp.), a rotifer (Brachionus calyciflorus), a snail (Lymnaea stagnalis), an amphipod (Hyalella azteca), a midge (Chironomus riparius), and an aquatic plant (Lemna minor). The 10% effect concentrations (EC10s) ranged from 98 μg total Al/L for D. rerio to 2175 μg total Al/L for L. minor. From these data and additional published data, species-sensitivity distributions (SSDs) were developed to derive concentrations protective of 95% of tested species (i.e., 50% lower confidence limit of a 5th percentile hazard concentration [HC5-50]). A generic HC5-50 (not adjusted for bioavailability) of 74.4 μg total Al/L was estimated using the SSD. An Al-specific biotic ligand model (BLM) was used to develop SSDs normalized for bioavailability based on site-specific water quality characteristics. Normalized HC5-50s ranged from 93.7 to 534 μg total Al/L for waters representing a range of European ecoregions, whereas a chronic HC5 calculated using US Environmental Protection Agency aquatic life criteria methods (i.e., a continuous criterion concentration [CCC]) was 125 μg total Al/L when normalized to Lake Superior water in the United States. The HC5-50 and CCC values for site-specific waters other than those in the present study can be obtained using the Al BLM. Environ Toxicol Chem 2018;37:36-48. © 2017 SETAC.
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The US Environmental Protection Agency's (USEPA's) current ambient water quality criteria (AWQC) for lead (Pb) in freshwater were developed in 1984. The criteria are adjusted for hardness,... more
The US Environmental Protection Agency's (USEPA's) current ambient water quality criteria (AWQC) for lead (Pb) in freshwater were developed in 1984. The criteria are adjusted for hardness, but more recent studies have demonstrated that other parameters, especially dissolved organic carbon (DOC) and pH, have a much stronger influence on Pb bioavailability. These recent studies have been used to support development of a biotic ligand model (BLM) for Pb in freshwater, such that acute and chronic Pb toxicity can be predicted over a wide range of water chemistry conditions. Following USEPA guidelines for AWQC development and using a methodology consistent with that used by the USEPA in developing its recommended BLM-based criteria for copper in 2007, we propose acute and chronic BLM-based AWQC for Pb in freshwater. In addition to the application of the BLM approach that can better account for site-specific Pb bioavailability, the toxicity data sets presented are much more robust than in 1984, and there are now sufficient chronic Pb toxicity data available that use of an acute-to-chronic ratio is no longer necessary. Over a range of North American surface waters with representative water chemistry conditions, proposed acute BLM-based Pb criteria ranged from approximately 20 to 1000 μg/L and chronic BLM-based Pb criteria ranged from approximately 0.3 to 40 μg/L. The lowest criteria were for water with low DOC (1.2 mg/L), pH (6.7), and hardness (4.3 mg/L as CaCO3), whereas the highest criteria were for water with high DOC (9.8 mg/L), pH (8.2), and hardness (288 mg/L as CaCO3 ). Environ Toxicol Chem 2017;36:2965-2973. © 2017 SETAC.
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Although it is well known that increasing water hardness and dissolved organic carbon (DOC) concentrations mitigate the toxicity of aluminum (Al) to freshwater organisms in acidic water (i.e., pH < 6), these effects... more
Although it is well known that increasing water hardness and dissolved organic carbon (DOC) concentrations mitigate the toxicity of aluminum (Al) to freshwater organisms in acidic water (i.e., pH < 6), these effects are less well characterized in natural waters at circumneutral pHs for which most aquatic life regulatory protection criteria apply (i.e., pH 6-8). The evaluation of Al toxicity under varying pH conditions may also be confounded by the presence of Al hydroxides and freshly precipitated Al in newly prepared test solutions. Aging and filtration of test solutions were found to greatly reduce toxicity, suggesting that toxicity from transient forms of Al could be minimized and that precipitated Al hydroxides contribute significantly to Al toxicity under circumneutral conditions, rather than dissolved or monomeric forms. Increasing pH, hardness, and DOC were found to have a protective effect against Al toxicity for fish (Pimephales promelas) and invertebrates (Ceriodaphnia dubia, Daphnia magna). For algae (Pseudokirchneriella subcapitata), the protective effects of increased hardness were only apparent at pH 6, less so at pH 7, and at pH 8, increased hardness appeared to increase the sensitivity of algae to Al. The results support the need for water quality-based aquatic life protection criteria for Al, rather than fixed value criteria, as being a more accurate predictor of Al toxicity in natural waters. Environ Toxicol Chem 2018;37:49-60. © 2017 SETAC.
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Research Interests: Crustacea, Risk assessment, Daphnia, Water Pollution, Biological Sciences, and 26 moreRisk Analysis, Heavy metals, Environmental Sciences, Models, Toxicity, Copper, Animals, Fishes, Freshwater Fish, Bioavailability, CHEMICAL SCIENCES, Theoretical Models, Biotic ligand model, Gills, Dissolved Organic Carbon, Risk Assessment, Lethal Dose, Environmental Toxicology and Chemistry, Cyprinidae, Acute Toxicity, Ligand, Environmental, Biological Availability, Ligands, Organic Chemicals, and Toxicity Test
... by Paul Paquin Kevin Brix Joseph Meyer Michael Salazar Martin Grosell 2007 Page 3. ... Principal Investigators: Paul R. Paquin, HydroQual Inc. Michael Salazar, Applied Biomonitoring Kevin Brix, EcoTox Martin Grosell, University of... more
... by Paul Paquin Kevin Brix Joseph Meyer Michael Salazar Martin Grosell 2007 Page 3. ... Principal Investigators: Paul R. Paquin, HydroQual Inc. Michael Salazar, Applied Biomonitoring Kevin Brix, EcoTox Martin Grosell, University of Miami Joseph Meyer, University of Wyoming ...
Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according... more
Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p values<0.000). The rate of copper release from tungsten bronze shot was 30 to 50 times lower than that from the copper shot, depending on pH (p<0.0000). The observed expected environmental concentration of c...
Research Interests: Wetlands, Water quality, Ecotoxicology, Daphnia, Multidisciplinary, and 19 moreToxicity, Copper, Ph, United States, Animals, Firearms, Dissolution, Organism, North America, Projectile, Analysis of Variance, Tungsten, Water Quality, Toxicity Tests, In Vitro Studies, Aquatic Toxicity, Species List, Environmental Protection Agency, and Hydrogen-Ion Concentration
A multimetal, multiple binding site version of the biotic ligand model (mBLM) has been developed for predicting and explaining the bioavailability and toxicity of mixtures of metals to aquatic organisms. The mBLM was constructed by... more
A multimetal, multiple binding site version of the biotic ligand model (mBLM) has been developed for predicting and explaining the bioavailability and toxicity of mixtures of metals to aquatic organisms. The mBLM was constructed by combining information from single-metal BLMs to preserve compatibility between the single-metal and multiple-metal approaches. The toxicities from individual metals were predicted by assuming additivity of the individual responses. Mixture toxicity was predicted based on both dissolved metal and mBLM-normalized bioavailable metal. Comparison of the 2 prediction methods indicates that metal mixtures frequently appear to have greater toxicity than an additive estimation of individual effects on a dissolved metal basis. However, on an mBLM-normalized basis, mixtures of metals appear to be additive or less than additive. This difference results from interactions between metals and ligands in solutions including natural organic matter, processes that are accounted for in the mBLM. As part of the mBLM approach, a technique for considering variability was developed to calculate confidence bounds (called response envelopes) around the central concentration-response relationship. Predictions using the mBLM and response envelope were compared with observed toxicity for a number of invertebrate and fish species. The results show that the mBLM is a useful tool for considering bioavailability when assessing the toxicity of metal mixtures. Environ Toxicol Chem 2015;34:777-787. © 2014 SETAC.
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Page 1. FACTORS TO CONSIDER IN ASSESSING THE POTENTIAL FOR EFFECTS DUE TO METALS Paul R Paquin1, Rooni Mathew1, Darin Damiani2 Robert C. Santore3, Kuen Ben Wu1,Dominic M. DiToro1,4 ... Kamunde, C., M. Grosell, JNA Lott and CM Wood, 2001.... more
Page 1. FACTORS TO CONSIDER IN ASSESSING THE POTENTIAL FOR EFFECTS DUE TO METALS Paul R Paquin1, Rooni Mathew1, Darin Damiani2 Robert C. Santore3, Kuen Ben Wu1,Dominic M. DiToro1,4 ... Kamunde, C., M. Grosell, JNA Lott and CM Wood, 2001. ...
Page 1. DEVELOPING SITE-SPECIFIC WATER QUALITY CRITERIA FOR METALS USING THE BIOTIC LIGAND MODEL Robert C. Santore1, Rooni Mathew2, Paul R Paquin2, Kuen Ben Wu2, Dominic DiToro2,3 1 HydroQual, Inc., 4914 West Genesee St. ... Abington... more
Page 1. DEVELOPING SITE-SPECIFIC WATER QUALITY CRITERIA FOR METALS USING THE BIOTIC LIGAND MODEL Robert C. Santore1, Rooni Mathew2, Paul R Paquin2, Kuen Ben Wu2, Dominic DiToro2,3 1 HydroQual, Inc., 4914 West Genesee St. ... Abington Ambler ...
Go to AGRIS search. SSSA special publication (1995). The CHESS model for calculating chemical equilibria in soils and solutions. ...
ABSTRACT The U.S. Environmental Protection Agency&amp;#39;s (USEPA) current ambient water quality criteria (AWQC) for cyanide were developed in 1984. Since this time, additional research on cyanide toxicity and analytical chemistry... more
ABSTRACT The U.S. Environmental Protection Agency&amp;#39;s (USEPA) current ambient water quality criteria (AWQC) for cyanide were developed in 1984. Since this time, additional research on cyanide toxicity and analytical chemistry has suggested that cyanide AWQC values need to be updated to reflect the current state-of-the-science and to ensure that the methods for implementing the cyanide AWQC reflect the bioavailable and toxic forms of cyanide. Therefore, the Water Environment Research Foundation (WERF) sponsored a reassessment of the AWQC for cyanide by initiating a thorough review of the current scientific literature on cyanide and conducting additional laboratory studies to further understand cyanide chemistry and toxicity. Consistent with the USEPA&amp;#39;s draft strategy for developing AWQC, this evaluation also considered whether the cyanide AWQC are protective of benthos, threatened and endangered (T&amp;amp;E) species, and aquatic-dependent wildlife. This reassessment of AWQC for cyanide resulted in proposed freshwater acute and chronic criteria of 23 and 4.8 μg CN/L, respectively, which are comparable to the current freshwater acute and chronic criteria of 22 and 5.2 μg CN/L (free cyanide). For saltwater organisms, the reassessment resulted in proposed acute and chronic criteria of 20 and 4.1 μg CN/L (free cyanide), respectively, compared to the current saltwater acute and chronic criteria which are both 1.0 μg CN/L. The difference in the current and proposed saltwater criteria values is attributed to recent cyanide toxicity testing with several crab species in the genus Cancer and the copepod Acartia tonsa, which suggests this genus is not as sensitive to cyanide as previous cyanide toxicity testing indicated. A sediment-based cyanide criterion does not appear warranted if it is assumed that benthic organisms are not inordinately more sensitive to cyanide than the water column organisms that drive the basis for the proposed freshwater and saltwater criteria (the available cyanide toxicity data do not suggest that they would be), and given that bioavailable forms of cyanide are not expected to accumulate appreciably in sediment. Cyanide should thus be effectively regulated based on water column-based criteria and concentrations. Based on a combination of available empirical and estimated cyanide toxicity values for T&amp;amp;E species, the proposed freshwater criteria appear to be protective of most T&amp;amp;E species, but any site-specific modifications that increase the cyanide AWQC for water bodies inhabited by T&amp;amp;E species is not recommended. Finally, the proposed freshwater AWQC for cyanide appear to be adequately protective of aquatic-dependent wildlife.