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Jing You - One of the best experts on this subject based on the ideXlab platform.
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contribution of pyrethroids in large urban rivers to Sediment Toxicity assessed with benthic invertebrates chironomus dilutus a case study in south china
Environmental Toxicology and Chemistry, 2017Co-Authors: Qian Han, Fei Cheng, Jing YouAbstract:The importance of pyrethroids as potential stressors to benthic organisms has gradually become evident in urban creeks; however, the occurrence and Toxicity of Sediment-associated pyrethroids are rarely studied in large rivers. In this context, 10 Sediments from a large urban river (Guangzhou reach of the Pearl River in China) were assessed for pyrethroid occurrence and Sediment Toxicity to the benthic invertebrate Chironomus dilutus. One half of the Sediments exhibited lethality to C. dilutus in a 10-d exposure and all surviving midges showed significant change of enzymatic activity. Moreover, mortality occurred during a 20-d exposure for all the Sediments, in accordance with the high hazard quotients to benthic species estimated from pyrethroid residues in Sediment. Pyrethroids were detectable in all Sediments with the concentrations ranging from 2.43 to 61.2 ng/g dry weight, and permethrin and cypermethrin dominated pyrethroid composition. Acute toxic units for pyrethroids ranged from 0.03 to 0.56 (cypermethrin accounted for 13-81%) and showed a direct relationship with Sediment mortality among the midges. This is consistent with the studies on small creeks in Guangzhou in which Sediment-bound cypermethrin was found as a main stressor to benthic invertebrates. Comparatively, Sediment Toxicity and pyrethroid residues in large rivers were significantly lower than those in nearby creeks (urban tributaries). The difference may be partially explained by differing flow rates and water-carrying capacity among waterbodies at different scales; further validation is required. Overall, extensive use of pyrethroids has caused a threat to benthic species not only in small creeks but also in large rivers. Environ Toxicol Chem 2017;36:3367-3375. © 2017 SETAC.
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effect directed analysis of toxicants in Sediment with combined passive dosing and in vivo Toxicity testing
Environmental Science & Technology, 2017Co-Authors: Yanli Wei, Tyler W Mehler, Eddy Y Zeng, Jing YouAbstract:Identifying key toxicants in Sediment is a great challenge, particularly if nontarget toxicants are involved. To identify the contaminants responsible for Sediment Toxicity to Chironomus dilutus in Guangzhou reach of the Pearl River in South China, passive dosing and in vivo Toxicity testing were incorporated into effect-directed analysis (EDA) to account for bioavailability. Fractionation of Sediment extracts was performed with gel permeation chromatography and reverse phase liquid chromatography sequentially. Polydimethylsiloxane served as passive dosing matrix for midge bioassays. The fractions showing abnormal enzymatic response were subject to a nontarget analysis, which screened out 15 candidate toxicants. The concentrations of the screened contaminants (log-based organic carbon normalized) in Sediments of 10 sites were compared to Sediment Toxicity (10 and 20 day mortality and 10 day enzymatic response) to C. dilutus using correlation analyses. The results suggested that oxidative stress induced by...
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identifying the causes of Sediment associated Toxicity in urban waterways in south china incorporating bioavailabillity based measurements into whole Sediment Toxicity identification evaluation
Environmental Toxicology and Chemistry, 2015Co-Authors: Jing YouAbstract:Sediments in urban waterways of Guangzhou, China, were contaminated by a variety of chemicals and showed prevalent Toxicity to benthic organisms. A combination of whole-Sediment Toxicity identification evaluation (TIE) and bioavailability-based extraction was used to identify the causes of Sediment Toxicity. Of the 6 Sediment samples collected, 4 caused 100% mortality to Chironomus dilutus in 10-d bioassays, and the potential toxicants were assessed using TIE in these Sediments after dilution. The results of phase I characterization showed that organic contaminants were the principal contributors to the mortality of the midges in 2 Sediments and that metals and organics jointly caused the mortality in the other 2 Sediments. Ammonia played no role in the mortality for any samples. Conventional toxic unit analysis in phase II testing identified Cr, Cu, Ni, Pb, and Zn as the toxic metals, with cypermethrin, lambda-cyhalothrin, deltamethrin, and fipronils being the toxic organics. To improve the accuracy of identifying the toxicants, 4-step sequential extraction and Tenax extraction were conducted to analyze the bioavailability of the metals and organics, respectively. Bioavailable toxic unit analysis narrowed the list of toxic contributors, and the putative toxicants included 3 metals (Zn, Ni, and Pb) and 3 pesticides (cypermethrin, lambda-cyhalothrin, and fipronils). Metals contributed to the mortality in all Sediments, but Sediment dilution reduced the Toxicity and confounded the characterization of Toxicity contribution from metals in 2 Sediments in phase I. Incorporating bioavailability-based measurements into whole-Sediment TIE improved the accuracy of identifying the causative toxicants in urban waterways where multiple stressors occurred and contributed to Sediment Toxicity jointly.
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assessment of Sediment risk in the north end of tai lake china integrating chemical analysis and chronic Toxicity testing with chironomus dilutus
Archives of Environmental Contamination and Toxicology, 2015Co-Authors: Jing YouAbstract:Whole life-cycle bioassays with Chironomus dilutus were performed to evaluate Sediment Toxicity in Tai Lake, a typical freshwater lake in China. Meanwhile, contaminants of concern were analyzed in Sediment. The Sediments in Tai Lake showed no acute mortality in 10-day testing to C. dilutus. After chronic exposure to the Sediments, however, adverse effects—including decreased survival and sublethal impairments of growth, emergence, and fecundity—were observed at most sites in Tai Lake. A variety of contaminants were detected in Sediment with the total concentrations in the range of 504–889 ng/g dry weight (dw) for polycyclic aromatic hydrocarbons, 0.56–1.81 ng/g dw for polychlorinated biphenyls, 38.6–87.8 ng/g dw for polybrominated diphenyl ethers, 8.34–14.2 ng/g dw for organochlorine pesticides, 1.27–2.95 ng/g dw for organophosphate pesticides, 0.11–0.21 ng/g dw for pyrethroid pesticides, and 332–609 µg/g dw for metals. Finally, a canonical correlation analysis was applied to link chronic Sediment Toxicity to the toxic units of individual contaminants. Results suggested that two pesticides (hexachlorocyclohexane and chlorpyrifos) and two metals (chromium and nickel) in Sediments from Tai Lake were the potential contributors to the noted Toxicity in C. dilutus in the life-cycle Toxicity testing. In conclusion, acute bioassays with the benthos were not sensitive enough to assess Sediment Toxicity in freshwater lakes in China, and it is desirable to integrate chronic Toxicity testing with chemical analysis to better understand Sediment risk.
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chronic Toxicity thresholds for Sediment associated benzo a pyrene in the midge chironomus dilutus
Archives of Environmental Contamination and Toxicology, 2014Co-Authors: Charlie Z Huang, Jing YouAbstract:Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in aquatic ecosystems and have been shown to be one of the causes of Sediment Toxicity to benthic invertebrates. Benzo[a]pyrene (BaP) was selected as a representative for the PAH family of compounds for developing chronic Sediment Toxicity thresholds for Chironomus dilutus. Life-cycle Toxicity testing was initiated using newly hatched midge larvae and terminated until hatch of the second generation. Median lethal concentrations were 92.5 ± 19.6 and 56.9 ± 1.76 μg/g organic carbon (OC) after exposing midges to Sediment-associated BaP for 20 days (before pupation) and 43 days (end of test), respectively. Sublethal Toxicity was described as 5 and 50 % effect concentrations (EC5 and EC50), and these were 6.63 ± 0.82 and 41.1 ± 1.61 μg/g OC for growth reduction at 20 days, respectively. Impairments of emergence and reproduction of C. dilutus were also assessed at the end of the testing, and the EC5 and EC50 values were 3.41 ± 0.53 and 26.9 ± 1.43 μg/g OC for emergence and 2.18 ± 0.34 and 13.4 ± 1.13 μg/g OC for reproduction, respectively. In addition, bioavailability-based chronic Toxicity thresholds were also established using Tenax-extractable BaP concentrations. Although more environmentally relevant, data regarding chronic Toxicity are less available than those regarding acute Toxicity. Therefore, establishing numeric chronic Toxicity thresholds for Sediment-associated BaP with the consideration of the bioavailability would improve the accuracy of assessing PAH-related Sediment Toxicity.
Michael J Lydy - One of the best experts on this subject based on the ideXlab platform.
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addition of contaminant bioavailability and species susceptibility to a Sediment Toxicity assessment application in an urban stream in china
Environmental Pollution, 2013Co-Authors: Baoquan Sun, Michael J Lydy, Xin Chen, Jing YouAbstract:Sediments collected from an urban creek in China exhibited high acute Toxicity to Hyalella azteca with 81.3% of Sediments being toxic. A toxic unit (TU) estimation demonstrated that the pyrethroid, cypermethrin, was the major contributor to Toxicity. The traditional TU approach, however, overestimated the Toxicity. Reduced bioavailability of Sediment-associated cypermethrin due to sequestration explained the overestimation. Additionally, antagonism among multiple contaminants and species susceptibility to various contaminants also contributed to the unexpectedly low Toxicity to H. azteca. Bioavailable TUs derived from the bioavailability-based approaches, Tenax extraction and matrix-solid phase microextraction (matrix-SPME), showed better correlations with the noted Toxicity compared to traditional TUs. As the first successful attempt to use matrix-SPME for estimating Toxicity caused by emerging insecticides in field Sediment, the present study found freely dissolved cypermethrin concentrations significantly improved the prediction of Sediment Toxicity to H. azteca compared to organic carbon normalized and Tenax extractable concentrations.
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identifying the cause of Sediment Toxicity in agricultural Sediments the role of pyrethroids and nine seldom measured hydrophobic pesticides
Chemosphere, 2013Co-Authors: Donald P Weston, Minghua Zhang, Yuping Ding, Michael J LydyAbstract:Few currently used agricultural pesticides are routinely monitored for in the environment. Even if concentrations are known, Sediment LC50 values are often lacking for common Sediment Toxicity testing species. To help fill this data gap, Sediments in California’s Central Valley were tested for nine hydrophobic pesticides seldom analyzed: abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin. Most were detected, but rarely at concentrations acutely toxic to Hyalella azteca or Chironomus dilutus. Only abamectin, fenpropathrin, and methyl parathion were found at concentrations of potential concern, and only in one or two samples. One-quarter of over 100 samples from agriculture-affected waterways exhibited Toxicity, and in three-fourths of the toxic samples, pyrethroids exceeded concentrations expected to cause Toxicity. The pyrethroid Bi-fen-thrin in particular, as well as lambda-cyhalothrin, cypermethrin, esfenvalerate, permethrin, and the organophosphate chlorpyrifos, were primarily responsible for the observed Toxicity, rather than the more novel analytes, despite the fact that much of the sampling targeted areas of greatest use of the novel pesticides.
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comparative analysis of whole Sediment and porewater Toxicity identification evaluation techniques for ammonia and non polar organic contaminants
Chemosphere, 2010Co-Authors: Tyler W Mehler, Jing You, Jonathan D Maul, Michael J LydyAbstract:Porewater and whole Sediment Toxicity identification evaluations (TIEs) were performed on contaminated Illinois River Sediment and compared using two standardized Toxicity-testing organisms (Ceriodaphnia dubia and Hyalella azteca). Results suggested that the choice of testing matrix (porewater versus whole Sediment) significantly influenced characterization of Toxicity. The porewater TIE suggested that ammonia was the major source of Toxicity, while the whole Sediment TIE indicated that non-polar organics, specifically polycyclic aromatic hydrocarbons, were the primary contributor to Toxicity, with ammonia being a secondary contributor to Toxicity. While the choice of test organism may have played a smaller role in the discordance between the TIEs, the data suggest that this factor alone could play a prevalent role in characterizing Toxicity in other TIE assessments. Because porewater and whole Sediment TIEs examine Sediment Toxicity differently, using both TIE approaches as part of a risk assessment may provide a more accurate risk estimate of Sediment Toxicity.
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distribution and Toxicity of Sediment associated pesticides in urban and agricultural waterways from illinois usa
Environmental Toxicology and Chemistry, 2010Co-Authors: Yuping Ding, Amanda D Harwood, Heather M Foslund, Michael J LydyAbstract:A statewide investigation of insecticide presence and Sediment Toxicity was conducted in Illinois, USA, from June to August 2008. Twenty Sediment samples were collected from urban areas throughout Illinois, and 49 Sediment samples were collected from 14 agriculture-dominated counties in central and southern Illinois. Ten-day Sediment Toxicity tests were conducted using the amphipod Hyalella azteca, and 59% of the urban sites and 2% of the agricultural locations sampled caused significant mortality in the amphipods. The field Sediments were analyzed for 29 pesticides, including 19 organochlorines, one organophosphate, and nine pyrethroids. The detection frequencies of organochlorines, chlorpyrifos, and pyrethroids were 95, 65, and 95%, respectively, for urban sites, and 45, 6.1, and 47%, respectively, for agricultural sites. Based on toxic unit analysis, bifenthrin was the main contributor to the detected mortality in urban Sediments. The present study provides the first broad assessment of pesticide prevalence in both urban and agriculture areas in Illinois. Environ. Toxicol. Chem. 2010;29:149–157. © 2009 SETAC
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whole Sediment Toxicity identification evaluation tools for pyrethroid insecticides iii temperature manipulation
Environmental Toxicology and Chemistry, 2009Co-Authors: Donald P Weston, Jing You, Amanda D Harwood, Michael J LydyAbstract:Since the Toxicity of pyrethroid insecticides is known to increase at low temperatures, the use of temperature manipulation was explored as a whole-Sediment Toxicity identification evaluation (TIE) tool to help identify Sediment samples in which pyrethroid insecticides are responsible for observed Toxicity. The amphipod Hyalella azteca is commonly used for Toxicity testing of Sediments at a 23 degrees C test temperature. However, a temperature reduction to 18 degrees C doubled the Toxicity of pyrethroids, and a further reduction to 13 degrees C tripled their Toxicity. A similar response, though less dramatic, was found for 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), and dissimilar temperature responses were seen for cadmium and the insecticide chlorpyrifos. Tests with field-collected Sediments containing pyrethroids and/or chlorpyrifos showed the expected thermal dependency in nearly all instances. The inverse relationship between temperature and Toxicity provides a simple approach to help establish when pyrethroids are the principal toxicant in a Sediment sample that could be used as a supplemental tool in concert with chemical analysis or other TIE manipulations. The phenomenon appears to be, in part, a consequence of a reduced ability to biotransform the toxic parent compound at cooler temperatures. The strong dependence of pyrethroid Toxicity on temperature has important ramifications for predicting their environmental effects, and the standard test temperature of 23 degrees C dramatically underestimates risk to resident fauna during the cooler months.
Christopher G. Ingersoll - One of the best experts on this subject based on the ideXlab platform.
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using an interlaboratory study to revise methods for conducting 10 d to 42 d water or Sediment Toxicity tests with hyalella azteca
Environmental Toxicology and Chemistry, 2016Co-Authors: Chris D Ivey, Christopher G. Ingersoll, William G Brumbaugh, Edward J Hammer, David R Mount, Russell J Hockett, Teresa J Norbergking, Dave Soucek, Lisa N TaylorAbstract:Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in Sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-Sediment Toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control Sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast-cerophyll-trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or Sediment Toxicity exposures with H. azteca. Environ Toxicol Chem 2016;35:2439-2447. © 2016 SETAC.
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development and application of freshwater Sediment Toxicity benchmarks for currently used pesticides
Science of The Total Environment, 2016Co-Authors: Lisa H Nowell, Christopher G. Ingersoll, Julia E Norman, Patrick W MoranAbstract:Abstract Sediment-Toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole Sediments. Two types of freshwater Sediment benchmarks for pesticides were developed using spiked-Sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret Sediment-Toxicity data or to assess the potential Toxicity of pesticides in whole Sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole Sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a Sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential Toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in Sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured Toxicity from whole-Sediment Toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant Toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting Toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics of Sediment, and uncertainty in TEB values. Additional evaluations of benchmarks in relation to Sediment chemistry and Toxicity are ongoing.
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contaminants in stream Sediments from seven united states metropolitan areas part ii Sediment Toxicity to the amphipod hyalella azteca and the midge chironomus dilutus
Archives of Environmental Contamination and Toxicology, 2013Co-Authors: N.e. Kemble, Christopher G. Ingersoll, Lisa H Nowell, Douglas K Hardesty, James L Kunz, Paul K Sibley, Daniel L Calhoun, Robert J Gilliom, Kathryn M Kuivila, Patrick W MoranAbstract:Relationships between Sediment Toxicity and Sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-Toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between Toxicity end points and Sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below Sediment-Toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin Toxicity threshold, 79 % were toxic to amphipods compared with 25 % Toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs, OC pesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants.
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ecological impacts of lead mining on ozark streams Toxicity of Sediment and pore water
Ecotoxicology and Environmental Safety, 2009Co-Authors: John M Besser, William G Brumbaugh, Ann L Allert, Barry C Poulton, Christopher J Schmitt, Christopher G. IngersollAbstract:Abstract We studied the Toxicity of Sediments downstream of lead–zinc mining areas in southeast Missouri, using chronic Sediment Toxicity tests with the amphipod, Hyalella azteca, and pore-water Toxicity tests with the daphnid, Ceriodaphnia dubia. Tests conducted in 2002 documented reduced survival of amphipods in stream Sediments collected near mining areas and reduced survival and reproduction of daphnids in most pore waters tested. Additional amphipod tests conducted in 2004 documented significant toxic effects of Sediments from three streams downstream of mining areas: Strother Creek, West Fork Black River, and Bee Fork. Greatest Toxicity occurred in Sediments from a 6-km reach of upper Strother Creek, but significant toxic effects occurred in Sediments collected at least 14 km downstream of mining in all three watersheds. Toxic effects were significantly correlated with metal concentrations (nickel, zinc, cadmium, and lead) in Sediments and pore waters and were generally consistent with predictions of metal Toxicity risks based on Sediment quality guidelines, although ammonia and manganese may also have contributed to Toxicity at a few sites. Responses of amphipods in Sediment Toxicity tests were significantly correlated with characteristics of benthic invertebrate communities in study streams. These results indicate that Toxicity of metals associated with Sediments contributes to adverse ecological effects in streams draining the Viburnum Trend mining district.
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predictions of Sediment Toxicity using consensus based freshwater Sediment quality guidelines
Archives of Environmental Contamination and Toxicology, 2001Co-Authors: Christopher G. Ingersoll, N.e. Kemble, Donald D. Macdonald, Judy L. Crane, N Wang, L J Field, Pamela S Haverland, R A Lindskoog, Corinne G Severn, D E SmorongAbstract:The objectives of this study were to compare approaches for evaluating the combined effects of chemical mixtures on the Toxicity in field-collected Sediments and to evaluate the ability of consensus-based probable effect concentrations (PECs) to predict Toxicity in a freshwater database on both a national and regional geographic basis. A database was developed from 92 published reports, which included a total of 1,657 samples with high-quality matching Sediment Toxicity and chemistry data from across North America. The database was comprised primarily of 10- to 14-day or 28- to 42-day Toxicity tests with the amphipod Hyalella azteca (designated as the HA10 or HA28 tests) and 10- to 14-day Toxicity tests with the midges Chironomus tentans or C. riparius (designated as the CS10 test). Mean PEC quotients were calculated to provide an overall measure of chemical contamination and to support an evaluation of the combined effects of multiple contaminants in Sediments. There was an overall increase in the incidence of Toxicity with an increase in the mean quotients in all three tests. A consistent increase in the Toxicity in all three tests occurred at a mean quotient > 0.5, however, the overall incidence of Toxicity was greater in the HA28 test compared to the short-term tests. The longer-term tests, in which survival and growth are measured, tend to be more sensitive than the shorter-term tests, with acute to chronic ratios on the order of six indicated for H. azteca. Different patterns were observed among the various procedures used to calculate mean quotients. For example, in the HA28 test, a relatively abrupt increase in Toxicity was associated with elevated polychlorinated biphenyls (PCBs) alone or with elevated polycyclic aromatic hydrocarbons (PAHs) alone, compared to the pattern of a gradual increase in Toxicity observed with quotients calculated using a combination of metals, PAHs, and PCBs. These analyses indicate that the different patterns in Toxicity may be the result of unique chemical signals associated with individual contaminants in samples. Though mean quotients can be used to classify samples as toxic or nontoxic, individual quotients might be useful in helping identify substances that may be causing or substantially contributing to the observed Toxicity. An increase in the incidence of Toxicity was observed with increasing mean quotients within most of the regions, basins, and areas in North America for all three Toxicity tests. The results of these analyses indicate that the consensus-based PECs can be used to reliably predict Toxicity of Sediments on both a regional and national basis.
Stuart L Simpson - One of the best experts on this subject based on the ideXlab platform.
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performance and sensitivity of rapid sublethal Sediment Toxicity tests with the amphipod melita plumulosa and copepod nitocra spinipes
Environmental Toxicology and Chemistry, 2011Co-Authors: Stuart L Simpson, David A SpadaroAbstract:Sublethal whole-Sediment Toxicity tests are an important tool for assessing the potential effects of contaminated Sediments. However, the longer duration required for evaluating potential chronic effects may increase endpoint variability and test costs compared to survival endpoints. In the present study we compare the performance and sensitivity to contaminants of 10-d sublethal Sediment Toxicity tests with the amphipod Melita plumulosa and harpacticoid copepod Nitocra spinipes. For both tests, sublethal effects were consistently observed when Sediment contaminant concentrations exceeded Sediment quality guideline (SQG) concentrations. The response of these bioassays in metal-contaminated Sediments was shown to conform ideally with respect to the mean SQG quotient calculated on the basis of the Australian and New Zealand lower SQG trigger value, with Toxicity being observed only in those Sediments where the mean quotient exceeded one. Better predictions of nonToxicity were obtained when dilute acid-extractable rather than total metal concentrations were used. Using the upper SQG, Toxicity frequently occurred at mean quotients below one. The effects were generally consistent with predictions from the acid-volatile sulfide and simultaneously extracted metal model. Effects on reproduction of M. plumulosa were detected for Sediments that did not cause effects on survival and highlighted the environmental relevance and importance of using these sublethal endpoints. When using four replicates for M. plumulosa and five replicates for N. spinipes, the endpoint variability (standard error) was less than 10%. Variations in Sediment particle size and organic carbon content did not affect endpoint variability. Both species are relatively easily cultured in the laboratory, and the estimated effort and cost of achieving the sublethal endpoints is 1.5 times that of the acute survival test endpoints.
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performance and sensitivity of rapid sublethal Sediment Toxicity tests with the amphipod melita plumulosa and copepod nitocra spinipes
Environmental Toxicology and Chemistry, 2011Co-Authors: Stuart L Simpson, David A SpadaroAbstract:Sublethal whole-Sediment Toxicity tests are an important tool for assessing the potential effects of contaminated Sediments. However, the longer duration required for evaluating potential chronic effects may increase endpoint variability and test costs compared to survival endpoints. In the present study we compare the performance and sensitivity to contaminants of 10-d sublethal Sediment Toxicity tests with the amphipod Melita plumulosa and harpacticoid copepod Nitocra spinipes. For both tests, sublethal effects were consistently observed when Sediment contaminant concentrations exceeded Sediment quality guideline (SQG) concentrations. The response of these bioassays in metal-contaminated Sediments was shown to conform ideally with respect to the mean SQG quotient calculated on the basis of the Australian and New Zealand lower SQG trigger value, with Toxicity being observed only in those Sediments where the mean quotient exceeded one. Better predictions of nonToxicity were obtained when dilute acid-extractable rather than total metal concentrations were used. Using the upper SQG, Toxicity frequently occurred at mean quotients below one. The effects were generally consistent with predictions from the acid-volatile sulfide and simultaneously extracted metal model. Effects on reproduction of M. plumulosa were detected for Sediments that did not cause effects on survival and highlighted the environmental relevance and importance of using these sublethal endpoints. When using four replicates for M. plumulosa and five replicates for N. spinipes, the endpoint variability (standard error) was less than 10%. Variations in Sediment particle size and organic carbon content did not affect endpoint variability. Both species are relatively easily cultured in the laboratory, and the estimated effort and cost of achieving the sublethal endpoints is 1.5 times that of the acute survival test endpoints. Environ. Toxicol. Chem. 2011;30:2326-2334. # 2011 SETAC
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exposure pathway models explain causality in whole Sediment Toxicity tests
Environmental Science & Technology, 2005Co-Authors: Stuart L Simpson, Catherine K KingAbstract:Measurements of lethal effect concentrations (LC50) and bioaccumulation following water-only and whole-Sediment exposures of the amphipod, Melita plumulosa, and the bivalve, Tellina deltoidalis, to copper, were combined with bioenergetic-based kinetic models of exposure pathways to explain causality in whole-Sediment Toxicity tests. For both organisms, lethal body concentrations (LBCs) were greater for water-only exposures than for Sediment exposures and indicated that the rate of copper accumulation and/or the mode of Toxicity of copper assimilated were different for dissolved and particulate phases. The net assimilation of copper, expressed as a lethal exposure concentration (LEC) that was independent of the postexposure copper efflux, was shown to better explain the observed Toxicity. The LEC of copper was the same for both water-only and whole-Sediment Toxicity tests. It is predicted that, for each species, a large range of effect concentrations may be measured for Sediments having the same total copp...
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exposure pathway models explain causality in whole Sediment Toxicity tests
Environmental Science & Technology, 2005Co-Authors: Stuart L Simpson, Catherine K KingAbstract:Measurements of lethal effect concentrations (LC50) and bioaccumulation following water-only and whole-Sediment exposures of the amphipod, Melita plumulosa, and the bivalve, Tellina deltoidalis, to copper, were combined with bioenergetic-based kinetic models of exposure pathways to explain causality in whole-Sediment Toxicity tests. For both organisms, lethal body concentrations (LBCs) were greater for water-only exposures than for Sediment exposures and indicated that the rate of copper accumulation and/or the mode of Toxicity of copper assimilated were different for dissolved and particulate phases. The net assimilation of copper, expressed as a lethal exposure concentration (LEC) that was independent of the postexposure copper efflux, was shown to better explain the observed Toxicity. The LEC of copper was the same for both water-only and whole-Sediment Toxicity tests. It is predicted that, for each species, a large range of effect concentrations may be measured for Sediments having the same total copper concentration. These are conditional effect concentrations, as their value will be determined by total copper concentrations, partitioning (Kd) relationships (Sediment properties), organism physiology (uptake rates from waters, assimilation efficiencies from solids), and organism feeding behavior (feeding selectivity). The importance of these factors to the development of Sediment quality guidelines for metals based on species sensitivity distributions is discussed.
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an assessment of five australian polychaetes and bivalves for use in whole Sediment Toxicity tests Toxicity and accumulation of copper and zinc from water and Sediment
Archives of Environmental Contamination and Toxicology, 2004Co-Authors: Catherine K King, Stuart L Simpson, M C Dowse, Dianne F JolleyAbstract:The suitability of two polychaete worms, Australonereis ehlersi and Nephtys australiensis, and three bivalves, Mysella anomala, Tellina deltoidalis, and Soletellina alba, were assessed for their potential use in whole-Sediment Toxicity tests. All species except A. ehlersi, which could not be tested because of poor survival in water-only tests, survived in salinities ranging from 18‰ to 34‰ during the 96-hour exposure period. No mortality was observed in any of the species exposed to Sediment compositions ranging from 100% silt to 100% sand for 10 days, thus demonstrating the high tolerance of the five species to a wide range of Sediment types. All species showed decreased survival after exposure to highly sulfidic Sediments in 10-day whole-Sediment tests. In 96-hour water-only tests, survival decreased, and copper accumulation in body tissues increased with exposure to increasing copper concentration for all species except A. ehlersi, which again could not be tested because of its poor survival in the absence of Sediment. S. alba and T. deltoidalis were the most sensitive species to aqueous copper (LC50s of 120 and 150 μg Cu/L, respectively). All species tested were relatively insensitive to dissolved zinc up to concentrations of approximately 1,000 μg/L. In addition and with the exception of N. australiensis, all species accumulated significant levels of zinc in their body tissues. Whole-Sediment tests were conducted over a 10-day period with copper-spiked (1,300 μg/g) and zinc-spiked (4,000 μg/g) Sediments equilibrated for sufficient time to ensure that pore water metal concentrations were well below concentrations shown to have any effect on organisms in water-only tests. Survival was decreased in the bivalves T. deltoidalis and S. alba after exposure to copper-spiked Sediments, and all species—except T. deltoidalis, in which 100% mortality was observed—accumulated copper in their tissues. Exposure to zinc-spiked Sediments significantly decreased the survival of only one species, T. deltoidalis. Both polychaetes appeared to regulate concentrations of zinc in their body tissues with no significant uptake of zinc occurring from the Sediment phase. Of the five species assessed in this study, T. deltoidalis was found to be the most sensitive to copper- and zinc-contaminated Sediments, and based on commonly used selection criteria (ASTM 2002a, ASTM 2002b, ASTM 2002c) is recommended for development as test species in whole-Sediment Toxicity tests.
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identifying the cause of Sediment Toxicity in agricultural Sediments the role of pyrethroids and nine seldom measured hydrophobic pesticides
Chemosphere, 2013Co-Authors: Donald P Weston, Minghua Zhang, Yuping Ding, Michael J LydyAbstract:Few currently used agricultural pesticides are routinely monitored for in the environment. Even if concentrations are known, Sediment LC50 values are often lacking for common Sediment Toxicity testing species. To help fill this data gap, Sediments in California’s Central Valley were tested for nine hydrophobic pesticides seldom analyzed: abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin. Most were detected, but rarely at concentrations acutely toxic to Hyalella azteca or Chironomus dilutus. Only abamectin, fenpropathrin, and methyl parathion were found at concentrations of potential concern, and only in one or two samples. One-quarter of over 100 samples from agriculture-affected waterways exhibited Toxicity, and in three-fourths of the toxic samples, pyrethroids exceeded concentrations expected to cause Toxicity. The pyrethroid Bi-fen-thrin in particular, as well as lambda-cyhalothrin, cypermethrin, esfenvalerate, permethrin, and the organophosphate chlorpyrifos, were primarily responsible for the observed Toxicity, rather than the more novel analytes, despite the fact that much of the sampling targeted areas of greatest use of the novel pesticides.
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environmental modeling and exposure assessment of Sediment associated pyrethroids in an agricultural watershed
PLOS ONE, 2011Co-Authors: Minghua ZhangAbstract:Synthetic pyrethroid insecticides have generated public concerns due to their increasing use and potential effects on aquatic ecosystems. A modeling system was developed in this study for simulating the transport processes and associated Sediment Toxicity of pyrethroids at coupled field/watershed scales. The model was tested in the Orestimba Creek watershed, an agriculturally intensive area in California' Central Valley. Model predictions were satisfactory when compared with measured suspended solid concentration (R2 = 0.536), pyrethroid toxic unit (0.576), and cumulative mortality of Hyalella azteca (0.570). The results indicated that Sediment Toxicity in the study area was strongly related to the concentration of pyrethroids in bed Sediment. Bifenthrin was identified as the dominant contributor to the Sediment Toxicity in recent years, accounting for 50–85% of predicted Toxicity units. In addition, more than 90% of the variation on the annual maximum toxic unit of pyrethroids was attributed to precipitation and prior application of bifenthrin in the late irrigation season. As one of the first studies simulating the dynamics and spatial variability of pyrethroids in fields and instreams, the modeling results provided useful information on new policies to be considered with respect to pyrethroid regulation. This study suggested two potential measures to efficiently reduce Sediment Toxicity by pyrethroids in the study area: [1] limiting bifenthrin use immediately before rainfall season; and [2] implementing conservation practices to retain soil on cropland.
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identifying the cause and source of Sediment Toxicity in an agriculture influenced creek
Environmental Toxicology and Chemistry, 2007Co-Authors: Donald P Weston, Minghua Zhang, Michael J LydyAbstract:Del Puerto Creek, an agriculturally influenced stream in northern California, USA, with a history of Sediment Toxicity, was used as a case study to determine the feasibility of using Sediment Toxicity testing and chemical analysis to identify the causative agent for the Toxicity and its sources. Testing with the amphipod Hyalella azteca confirmed historical Toxicity and identified a point along the creek at which there was an abrupt increase in Sediment Toxicity that persisted for at least 6 km downstream. Three recently developed whole Sediment Toxicity identification evaluation manipulations, temperature reduction, piperonyl butoxide addition, and esterase addition, were applied to Sediment from one site and were suggestive of a pyrethroid as the cause for Toxicity. Utilizing published median lethal concentration (LC50) values in a toxic unit analysis, the pyrethroid insecticide bifenthrin was identified as the primary contributor to Toxicity in nearly all sites at which Toxicity was observed, with occasional additional contributions from the pyrethroids lambda-cyhalothrin, esfenvalerate, and cyfluthrin. Most agricultural drains discharging to Del Puerto Creek contained bifenthrin in their Sediments at concentrations near or above acutely toxic concentrations. However, only one drain contained Sediments with bifenthrin concentrations approaching the concentrations measured in creek Sediments. This fact, along with the proximity of that particular discharge to the location in the creek with the highest concentrations, suggested that one drain may be responsible for much of the Toxicity and pyrethroid residues in creek Sediments. The methods employed in this study are likely to be of considerable value in total maximum daily load efforts in Del Puerto Creek or other California surface water bodies known to have pyrethroid-related aquatic Toxicity.