The Experts below are selected from a list of 58110 Experts worldwide ranked by ideXlab platform
Cai Chao - One of the best experts on this subject based on the ideXlab platform.
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the effects of sewage sludge and sewage sludge biochar on pahs and potentially toxic element Bioaccumulation in cucumis sativa l
Chemosphere, 2014Co-Authors: Muhammad Waqas, Sardar Khan, Huang Qing, Brian J Reid, Cai ChaoAbstract:Abstract The presence of contaminants such as polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs), including As, Cd, Cu, Pb and Zn, restricts the application of sewage sludge (SS) to agricultural land. This research established that the conversion of SS to SS biochar (SSBC) significantly ( p ⩽ 0.01) decreased PAH and available PTE concentrations. Once added to soil both SS and SSBC significantly (p ⩽ 0.05) decrease PAH availability. Bioaccumulation of PAHs into Cucumis sativa L. was reduced by both SSBC (44–57%) and (to a lesser extent 20–36%) by SS. Following addition to soil SSBC significantly ( p ⩽ 0.05) reduced available PTEs (except Cd), while SS significantly ( p ⩽ 0.05) increased PTE availability. As a consequence SSBC significantly ( p ⩽ 0.05) reduced PTE Bioaccumulation (except Cd and Zn), while SS increased PTE Bioaccumulation. These results suggest SSBC to be a candidate for soil amendment that offers advantages over SS in terms of PAH/PTE Bioaccumulation mitigation.
J.d. Lebrun - One of the best experts on this subject based on the ideXlab platform.
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Comparison in waterborne Cu, Ni and Pb Bioaccumulation kinetics between different gammarid species and populations: Natural variability and influence of metal exposure history
Aquatic Toxicology, 2017Co-Authors: N. Urien, E. Uher, A. Farfarana, A. Chaumot, L.c. Fechner, O. Geffard, J.d. LebrunAbstract:Kinetic parameters (uptake from solution and elimination rate constants) of Cu, Ni and Pb Bioaccumulation were determined from two Gammarus pulex and three Gammarus fossrum wild populations collected from reference sites throughout France in order to assess the inter-species and the natural inter-population variability of metal Bioaccumulation kinetics in that sentinel organism. For that, each population was independently exposed for seven days to either 2.5 μg L−1 Cu (39.3 nM), 40 μg L−1 Ni (681 nM) or 10 μg L−1 Pb (48.3 nM) in laboratory controlled conditions, and then placed in unexposed microcosms for a 7-day depuration period. In the same way, the possible influence of metal exposure history on subsequent metal Bioaccumulation kinetics was addressed by collecting wild gammarids from three populations inhabiting stations contaminated either by Cd, Pb or both Pb and Ni (named pre-exposed thereafter). In these pre-exposed organisms, assessment of any changes in metal Bioaccumulation kinetics was achieved by comparison with the natural variability of kinetic parameters defined from reference populations. Results showed that in all studied populations (reference and pre-exposed) no significant Cu Bioaccumulation was observed at the exposure concentration of 2.5 μg L−1. Concerning the reference populations, no significant differences in Ni and Pb Bioaccumulation kinetics between the two species (G. pulex and G. fossarum) was observed allowing us to consider all the five reference populations to determine the inter-population natural variability, which was found to be relatively low (kinetic parameters determined for each population remained within a factor of 2 of the minimum and maximum values). Organisms from the population exhibiting a Pb exposure history presented reduced Ni uptake and elimination rate constants, whereas no influence on Ni kinetic parameters was observed in organisms from the population exhibiting an exposure history to both Ni and Pb. Furthermore Pb Bioaccumulation kinetics were unaffected whatever the condition of pre-exposure in natural environment. Finally, these results highlight the complexity of confounding factors, such as metal exposure history, that influence metal Bioaccumulation processes and showed that pre-exposure to one metal can cause changes in the Bioaccumulation kinetics of other metals. These results also address the question of the underlying mechanisms developed by organisms to cope with metal contamination.
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Contribution of aqueous and dietary uptakes to lead (Pb) Bioaccumulation in Gammarus pulex: From multipathway modeling to in situ validation
Ecotoxicology and Environmental Safety, 2016Co-Authors: R. Hadji, N. Urien, E. Uher, L.c. Fechner, J.d. LebrunAbstract:Abstract Although dynamic approaches are nowadays used increasingly to describe metal Bioaccumulation in aquatic organisms, the validation of such laboratory-derived modeling is rarely assessed under environmental conditions. Furthermore, information on Bioaccumulation kinetics of Pb and the significance of its uptake by dietary route is scarce in freshwater species. This study aims at modeling aqueous and dietary uptakes of Pb in the litter-degrader Gammarus pulex and assessing the predictive quality of multipathway modeling from in situ Bioaccumulation data. In microcosms, G. pulex were exposed to environmentally realistic concentrations of Pb (from 0.1 to 10 µg/L) in the presence of Pb-contaminated poplar leaves, which were enclosed or not in a net to distinguish aqueous and dietary uptakes. Results show that water and food both constitute contamination sources for gammarids. Establishing biodynamic parameters involved in Pb aqueous and dietary uptake and elimination rates enabled to construct a multipathway model to describe Pb Bioaccumulation in gammarids. This laboratory-derived model successfully predicted Bioaccumulation measured in native populations of G. pulex collected in situ when local litter was used as dietary exposure source. This study demonstrates not only the suitable applicability of biodynamic parameters for predicting Pb Bioaccumulation but also the necessity of taking dietary uptake into account for a better interpretation of the gammarids’ contamination in natural conditions.
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Contrasting abilities of metal Bioaccumulation in Gammarus populations with different exposure histories
2015Co-Authors: N. Urien, J.d. Lebrun, A. Farfarana, A. Chaumot, L.c. Fechner, Olivier GeffardAbstract:Kinetic models are used to link metal exposure to metal contamination in aquatic organisms and enable also the prediction of metal Bioaccumulation. Kinetic models are characterised by kinetic parameters (uptake and elimination rate constants) which can be determined in controlled conditions. “Global” kinetic parameters for Cd, Pb and Ni have been established in five naïve populations of gammarids. Gammarids can, however, live in rivers exhibiting metal contamination to which organisms may adapt physiologically. Adaptation can result in the modulation of Bioaccumulation abilities i.e. kinetic parameters. This may limit the environmental relevance of kinetic models and the reliability of Bioaccumulation predictions. The aim of thsi study was to assess the Bioaccumulation abilities of metals in gammarids chronically exposed to metals in situ by (i) determining the kinetic parameters describing Cd, Pb and Ni Bioaccumulation in populations of gammarids chronically exposed to metals in situ, (ii) comparing the kinetic parameters with “global” kinetic parameters already determined in five naïve populations of gammarids.
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Essential metal contents in indigenous gammarids related to exposure levels at the river basin scale: metal-dependent models of Bioaccumulation and geochemical correlations
Science of the Total Environment, 2014Co-Authors: J.d. Lebrun, E. Uher, M.h. Tusseau Vuillemin, C. Gourlay FranncéAbstract:Biomonitoring, assumed to be an integrative measurement of the chemical exposure of aquatic organisms, is not straightforward for essential metals because they can be actively regulated by animals. Although increasing Bioaccumulation with exposure levels is a crucial endpoint for the development of biomonitors, it is rarely verified in real environments, where the metal concentrations are rather low and vary little. This study was designed at the scale of a river basin to assess the ability of Gammarus pulex indigenous populations to accumulate Cu, Zn and Mn in realistic exposure conditions. During two annual campaigns, water and gammarids were collected at various sites contrasted in terms of physicochemistry and contamination. The results show significant relationships between metal concentrations in animals and in freshwaters established by conceptual models of Bioaccumulation, but with patterns specific to each metal (base level, internal regulation and maximal accumulation). In particular, a saturation process of Cu accumulation occurs at environmental exposure levels, unlike Mn and Zn. Statistical analyses performed from field data show that Cu and Zn Bioaccumulations may be influenced by a complex combination of geochemical variables, unlike Mn. We conclude that G. pulex is a useful candidate to monitor metal bioavailability in freshwaters due to its responsiveness to low exposures of surrounding environments. Nevertheless, a reliable quantification of bioavailability of essential metals requires characterizing some geochemical effects on metal Bioaccumulation.
Marianna Taffi - One of the best experts on this subject based on the ideXlab platform.
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Bioaccumulation modelling and sensitivity analysis for discovering key players in contaminated food webs the case study of pcbs in the adriatic sea
Ecological Modelling, 2015Co-Authors: Marianna Taffi, Nicola Paoletti, Sandra Pucciarelli, Mauro MariniAbstract:Modelling Bioaccumulation processes at the food web level is the main step to analyse the effects of pollutants at the global ecosystem level. A crucial question is understanding which species play a key role in the trophic transfer of contaminants to disclose the contribution of feeding linkages and the importance of trophic dependencies in Bioaccumulation dynamics. In this work we present a computational framework to model the Bioaccumulation of organic chemicals in aquatic food webs, and to discover key species in polluted ecosystems. As a result, we reconstruct the first PCBs Bioaccumulation model of the Adriatic food web, estimated after an extensive review of published concentration data. We define a novel index aimed to identify the key species in contaminated networks, sensitivity centrality, and based on sensitivity analysis. The index is computed from a dynamic ODE model parametrised from the estimated PCBs Bioaccumulation model and compared with a set of established trophic indices of centrality. Results evidence the occurrence of PCBs biomagnification in the Adriatic food web, and highlight the dependence of Bioaccumulation on trophic dynamics and external factors like fishing activity. We demonstrate the effectiveness of the introduced sensitivity centrality in identifying the set of species with the highest impact on the total contaminant flows and on the efficiency of contaminant transport within the food web.
Jon A Arnot - One of the best experts on this subject based on the ideXlab platform.
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A weight-of-evidence approach for the Bioaccumulation assessment of triclosan in aquatic species.
Science of The Total Environment, 2017Co-Authors: Jon A Arnot, Sascha Pawlowski, Samantha ChampAbstract:Abstract The Bioaccumulation assessment of chemicals is challenging because of various metrics and criteria, multiple lines of evidence and underlying uncertainty in the data. Measured in vivo laboratory and field Bioaccumulation data are generally considered preferable; however, quantitative structure-activity relationships (QSARs), mass balance models and in vitro data can also be considered. This case study critically evaluates in vivo, in vitro and in silico data and provides new data for the Bioaccumulation assessment of triclosan (TCS). The review focusses on measured fish bioconcentration factors (BCFs) because this is the most commonly used regulatory metric. Reported measured fish BCFs range from about 20 to 8700 L/kg-ww spanning a range of possible Bioaccumulation assessment outcomes, i.e. from “not bioaccumulative” to “very bioaccumulative”. Estimated biotransformation rate constants for fish obtained from in vivo, in vitro and in silico methods show general consensus fostering confidence in the selection of plausible values to confront uncertainty in the measured fish BCF tests. Other measurements (lines of evidence) from various species are also collected and reviewed. The estimated biotransformation rate constants and selected chemical property data are used to parameterize Bioaccumulation models for aquatic species. Collectively the available lines of evidence are presented using a weight of evidence approach for assessing the Bioaccumulation of TCS in aquatic species. Acceptable quality measured data and model predictions for TCS BCFs and Bioaccumulation factors are lower than 2000 L/kg. Biomagnification factors are
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use of the Bioaccumulation factor to screen chemicals for Bioaccumulation potential
Environmental Toxicology and Chemistry, 2012Co-Authors: Jed Costanza, David G Lynch, Robert S Boethling, Jon A ArnotAbstract:The fish bioconcentration factor (BCF), as calculated from controlled laboratory tests, is commonly used in chemical management programs to screen chemicals for Bioaccumulation potential. The Bioaccumulation factor (BAF), as calculated from field-caught fish, is more ecologically relevant because it accounts for dietary, respiratory, and dermal exposures. The BCFBAF™ program in the U.S. Environmental Protection Agency's Estimation Programs Interface Suite (EPI Suite™ Ver 4.10) screening-level tool includes the Arnot-Gobas quantitative structure-activity relationship model to estimate BAFs for organic chemicals in fish. Bioaccumulation factors can be greater than BCFs, suggesting that using the BAF rather than the BCF for screening Bioaccumulation potential could have regulatory and resource implications for chemical assessment programs. To evaluate these potential implications, BCFBAF was used to calculate BAFs and BCFs for 6,034 U.S. high- and medium-production volume chemicals. The results indicate no change in the Bioaccumulation rating for 86% of these chemicals, with 3% receiving lower and 11% receiving higher Bioaccumulation ratings when using the BAF rather than the BCF. All chemicals that received higher Bioaccumulation ratings had log K(OW ) values greater than 4.02, in which a chemical's BAF was more representative of field-based Bioaccumulation than its BCF. Similar results were obtained for 374 new chemicals. Screening based on BAFs provides ecologically relevant results without a substantial increase in resources needed for assessments or the number of chemicals screened as being of concern for Bioaccumulation potential.
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Comparing laboratory and field measured Bioaccumulation endpoints.
Integrated Environmental Assessment and Management, 2011Co-Authors: Lawrence P. Burkhard, Jon A Arnot, Thomas F. Parkerton, Michelle R. Embry, Kevin J. Farley, Robert A. Hoke, Masaru Kitano, Heather A. Leslie, Guilherme R. Lotufo, Keith SappingtonAbstract:An approach for comparing laboratory and field measures of Bioaccumulation is presented to facilitate the interpretation of different sources of Bioaccumulation data. Differences in numerical scales and units are eliminated by converting the data to dimensionless fugacity (or concentration-normalized) ratios. The approach expresses Bioaccumulation metrics in terms of the equilibrium status of the chemical, with respect to a reference phase. When the fugacity ratios of the Bioaccumulation metrics are plotted, the degree of variability within and across metrics is easily visualized for a given chemical because their numerical scales are the same for all endpoints. Fugacity ratios greater than 1 indicate an increase in chemical thermodynamic activity in organisms with respect to a reference phase (e.g., biomagnification). Fugacity ratios less than 1 indicate a decrease in chemical thermodynamic activity in organisms with respect to a reference phase (e.g., biodilution). This method provides a holistic, weight-of-evidence approach for assessing the biomagnification potential of individual chemicals because bioconcentration factors, Bioaccumulation factors, biota-sediment accumulation factors, biomagnification factors, biota-suspended solids accumulation factors, and trophic magnification factors can be included in the evaluation. The approach is illustrated using a total 2393 measured data points from 171 reports, for 15 nonionic organic chemicals that were selected based on data availability, a range of physicochemical partitioning properties, and biotransformation rates. Laboratory and field fugacity ratios derived from the various Bioaccumulation metrics were generally consistent in categorizing substances with respect to either an increased or decreased thermodynamic status in biota, i.e., biomagnification or biodilution, respectively. The proposed comparative Bioaccumulation endpoint assessment method could therefore be considered for decision making in a chemicals management context.
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Molecular size cutoff criteria for screening Bioaccumulation potential: Fact or fiction?
Integrated Environmental Assessment and Management, 2010Co-Authors: Jon A Arnot, Michelle I. Arnot, Donald Mackay, Yves Couillard, Drew B. Macdonald, Mark Bonnell, Pat DoyleAbstract:It has been asserted that, when screening chemicals for Bioaccumulation potential, molecular size cutoff criteria (or indicators) can be applied above which no, or limited, Bioaccumulation is expected. The suggested molecular size values have increased over time as more measurements have become available. Most of the proposed criteria have been derived from unevaluated fish bioconcentration factor (BCF) data, and less than 5% of existing organic substances have measured BCFs.We critically review the proposed criteria, first by considering other factors that may also contribute to reduced Bioaccumulation for larger molecules, namely, reduced bioavailability in the water column, reduced rate of uptake corresponding to reduced diffusion rates, and the effects of biotransformation and growth dilution. An evaluated BCF and Bioaccumulation factor (BAF) database for more than 700 substances and dietary uptake efficiency data are compared against proposed cutoff values. We examine errors associated with interpreting BCF data, particularly for developing molecular size criteria of Bioaccumulation potential. Reduced Bioaccumulation that is often associated with larger molecular size can be explained by factors other than molecular size, and there is evidence of absorption of molecules exceeding the proposed cutoff criteria. The available data do not support strict cutoff criteria, indicating that the proposed values are incorrect. Rather than assessing Bioaccumulation using specific chemical properties in isolation, holistic methods that account for competing rates of uptake and elimination in an organism are recommended. An integrated testing strategy is suggested to improve knowledge of the absorption and Bioaccumulation of large substances.
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a food web Bioaccumulation model for organic chemicals in aquatic ecosystems
Environmental Toxicology and Chemistry, 2004Co-Authors: Jon A Arnot, Frank A. P. C. GobasAbstract:The present study examines a new Bioaccumulation model for hydrophobic organic chemicals in aquatic food webs. The purpose of the model is to provide site-specific estimates of chemical concentrations and associated bioconcentration factors, Bioaccumulation factors, and biota-sediment accumulation factors in organisms of aquatic food webs using a limited number of chemical, organism, and site-specific data inputs. The model is a modification of a previous model and incorporates new insights regarding the mechanism of Bioaccumulation derived from laboratory experiments and field studies as well as improvements in model parameterization. The new elements of the model include: A model for the partitioning of chemicals into organisms; kinetic models for predicting chemical concentrations in algae, phytoplankton, and zooplankton; new allometric relationships for predicting gill ventilation rates in a wide range of aquatic species; and a mechanistic model for predicting gastrointestinal magnification of organic chemicals in a range of species. Model performance is evaluated using empirical data from three different freshwater ecosystems involving 1,019 observations for 35 species and 64 chemicals. The effects of each modification on the model's performance are illustrated. The new model is able to provide better estimates of Bioaccumulation factors in comparison to the previous food web Bioaccumulation model while the model input requirements remain largely unchanged.
Mauro Marini - One of the best experts on this subject based on the ideXlab platform.
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Bioaccumulation modelling and sensitivity analysis for discovering key players in contaminated food webs the case study of pcbs in the adriatic sea
Ecological Modelling, 2015Co-Authors: Marianna Taffi, Nicola Paoletti, Sandra Pucciarelli, Mauro MariniAbstract:Modelling Bioaccumulation processes at the food web level is the main step to analyse the effects of pollutants at the global ecosystem level. A crucial question is understanding which species play a key role in the trophic transfer of contaminants to disclose the contribution of feeding linkages and the importance of trophic dependencies in Bioaccumulation dynamics. In this work we present a computational framework to model the Bioaccumulation of organic chemicals in aquatic food webs, and to discover key species in polluted ecosystems. As a result, we reconstruct the first PCBs Bioaccumulation model of the Adriatic food web, estimated after an extensive review of published concentration data. We define a novel index aimed to identify the key species in contaminated networks, sensitivity centrality, and based on sensitivity analysis. The index is computed from a dynamic ODE model parametrised from the estimated PCBs Bioaccumulation model and compared with a set of established trophic indices of centrality. Results evidence the occurrence of PCBs biomagnification in the Adriatic food web, and highlight the dependence of Bioaccumulation on trophic dynamics and external factors like fishing activity. We demonstrate the effectiveness of the introduced sensitivity centrality in identifying the set of species with the highest impact on the total contaminant flows and on the efficiency of contaminant transport within the food web.
