| 1. |
- Liu, Lianhua, et al.
(författare)
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Heavy metal accumulation, geochemical fractions, and loadings in two agricultural watersheds with distinct climate conditions
- 2020
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 389
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Tidskriftsartikel (refereegranskat)abstract
- The main aim of this study was to explore the effects of climate conditions on the transport and transformation of heavy metals. Sedimentary geochemical analysis and watershed modeling were used to investigate the distinctions between heavy metal pollution under different climate conditions. The results showed that the average concentrations of Cu, Cd, and Pb in sediments of the subtropical watershed (36.64, 0.60, and 133.69 mg/kg, respectively) were higher than those of the temperate watershed (26.58, 0.19, and 23.17 mg/kg, respectively) because of surface runoff-induced heavy metal loadings under higher precipitation. Also, the labile fractions, which mainly originated from anthropogenic sources, showed higher percentages in the subtropical watershed (67.84-91.33%), thereby indicating that the transport of heavy metals was promoted by surface runoff. Moreover, higher percentages of acid-soluble fractions of Cu and Pb (23.55-33.60%) in the subtropical watershed suggested that higher temperatures accelerated the transformation of heavy metal fractions, thus contributing to the transportation of heavy metals. Overall, climate conditions were the dominant factors for the differences between the subtropical and temperate watersheds. The results of this study suggest that the effects of climate conditions on the transport, enrichment, and bioavailability of heavy metals are of great significance. Such effects should therefore be the focus of future studies.
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| 2. |
- Mansouri, Kamel, et al.
(författare)
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CoMPARA : Collaborative Modeling Project for Androgen Receptor Activity
- 2020
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 128:2, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Endocrine disrupting chemicals (EDCs) are xenobiotics that mimic the interaction of natural hormones and alter synthesis, transport, or metabolic pathways. The prospect of EDCs causing adverse health effects in humans and wildlife has led to the development of scientific and regulatory approaches for evaluating bioactivity. This need is being addressed using high-throughput screening (HTS) in vitro approaches and computational modeling.OBJECTIVES: In support of the Endocrine Disruptor Screening Program, the U.S. Environmental Protection Agency (EPA) led two worldwide consortiums to virtually screen chemicals for their potential estrogenic and androgenic activities. Here, we describe the Collaborative Modeling Project for Androgen Receptor Activity (CoMPARA) efforts, which follows the steps of the Collaborative Estrogen Receptor Activity Prediction Project (CERAPP).METHODS: The CoMPARA list of screened chemicals built on CERAPP's list of 32,464 chemicals to include additional chemicals of interest, as well as simulated ToxCast (TM) metabolites, totaling 55,450 chemical structures. Computational toxicology scientists from 25 international groups contributed 91 predictive models for binding, agonist, and antagonist activity predictions. Models were underpinned by a common training set of 1,746 chemicals compiled from a combined data set of 11 ToxCast (TM)/Tox21 HTS in vitro assays.RESULTS: The resulting models were evaluated using curated literature data extracted from different sources. To overcome the limitations of single-model approaches, CoMPARA predictions were combined into consensus models that provided averaged predictive accuracy of approximately 80% for the evaluation set.DISCUSSION: The strengths and limitations of the consensus predictions were discussed with example chemicals; then, the models were implemented into the free and open-source OPERA application to enable screening of new chemicals with a defined applicability domain and accuracy assessment. This implementation was used to screen the entire EPA DSSTox database of similar to 875,000 chemicals, and their predicted AR activities have been made available on the EPA CompTox Chemicals dashboard and National Toxicology Program's Integrated Chemical Environment.
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| 3. |
- Ouyang, Wei, et al.
(författare)
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Temporal-spatial patterns of three types of pesticide loadings in a middle-high latitude agricultural watershed
- 2017
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 122, s. 377-386
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Tidskriftsartikel (refereegranskat)abstract
- Pesticide loadings to watersheds increase during agricultural development and may vary in accordance with different crop types and seasons. High pesticide loadings can potentially result in polluted stream water. The objective of this study was to determine the pesticide loadings and concentrations of three typical pesticides (atrazine, oxadiazon, and isoprothiolane) in river water from a middle high latitude agricultural watershed in northern China. During this study, we evaluated the watershed pesticide loss patterns for two crop types over three decades. For this purpose, we integrated data from field investigations, laboratory experiments, and modeling simulations involving a distributed hydrological solute transport model (Soil and Water Assessment Tool, SWAT). SWAT was employed to compare the temporal spatial fate and behaviors of atrazine, oxadiazon, and isoprothiolane from 1990 to 2014 in a watershed area amounting to 141.5 km(2). The results showed that the three pesticides could be detected at different locations throughout the watershed, and isoprothiolane was detected at the maximum value of 1.082 mu g/L in surface runoff of paddy land. The temporal trend for the yearly loading of atrazine decreased slightly over time, but the trends for oxadiazon and isoprothiolane increased markedly over an 18-year analysis period. In regard to the pesticide concentrations in water, atrazine was associated with the largest value of nearly 1.4 mu g/L. July and August were the found to be prime periods for pesticide loss from paddy land, and the biggest monthly loss of atrazine from dryland appeared in June. Under similar usage conditions, isoprothiolane loading from paddy fields ranked as the largest one among the three types of pesticides and reached up to 17 g/ha. Limited monitoring data were useful for validating the model, which yielded valuable temporal-spatial data on the fate of pesticides in this watershed. With the expansion of paddy rice cultivation, risks for pesticide contamination of water bodies will increase. The results of this study should be valuable for future exposure and risk assessments aimed at protecting the environment and human health.
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