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Acute toxicity of antimony pentavalent to neonatal Daphnia magna and the influence of water quality parameters were investigated, and enzymatic activities of organisms at environmentally relevant levels of antimony were determined. EC 50 values of antimony to neonatal D. magna were 90.3 and 63.8 mg/L at 24 and 48 h of exposure, respectively. Dissolved organic matter (FA and HA) and cation (Ca2+, Mg2+ or Na+) had significant protective effects on D. magna against antimony toxicity. With increasing pH in the range from 7.4 to 8.5, increase of EC 50 were observed due to the competition of OH- on biotic ligands. Based on the biotic ligand model (BLM) concept, stability constants for the binding of Sb(OH) 6 - and OH- to the biotic ligand were estimated, and the Log K XSb (OH) 6 - and Log K XOH - were 3.137 and 2.859, respectively. Moreover, antimony exposure in low concentrations significantly increased MDA levels and maybe exert oxidative stress to the organisms. Antimony can also induce toxicity in D. magna by affecting oxidative stress and neurotransmitter systems. The relatively comprehensive toxicological data can contribute to the toxicity prediction and ecological risk assessments of antimony. [Display omitted] • FA and HA weaken Sb toxicity to Daphnia magna. • Ca2+, Mg2+ and Na+ have significant protective effects against Sb toxicity. • Low levels of Sb exhibit oxidative stress and neurotoxicity on Daphnia magna. • Constants for the binding of Sb(OH) 6 - with the competition of OH- was calculated. [ABSTRACT FROM AUTHOR]

Antimony (Sb) persists in environmental media and can be toxic to aquatic organisms and humans. Although China is the primary Sb-producing country, the levels of Sb contamination and their potential risk to water resources remain unclear. This study provides an overview of Sb contamination in surface water and centralized drinking water sources across China and assesses its potential ecological and human health risks. Species sensitivity distribution was used to derive acute and chronic aquatic life criteria for Sb, which were 511.7 μg/L and 148.3 μg/L, respectively. Zooplankton were determined to be the most sensitive species, and fish were the least sensitive. Sb contamination in China is more serious than other countries. Risk quotients were used to assess the ecological risks of Sb. Chronic ecological risk quotients of 0.0013–27.39 were identified for surface water located near Sb mines. The highest values indicate high risk, particularly for zooplankton species. Exposure characteristics for the Chinese population across age group, sex, season, and region were used to assess the non-carcinogenic risk of Sb in centralized drinking water sources in China. Hazard quotients of 0.001–0.99 were found for these centralized drinking water sources. The non-carcinogenic risk posed by Sb was acceptable in the majority of locations, except in Hunan Province, which had the highest hazard quotient (approximately 1). This province contains the main Sb mining area in China, which poses a relatively large threat to human health. The Sb health risk for children was significantly higher than adults, but there was no significant difference in risk between men and women. The Sb drinking water guidance value to protect human health was calculated to be 19.65 μg/L for Chinese population. The results of this ecological and human health risk assessment highlight the importance of clean Sb production to reduce the negative effects of Sb contamination in China. [Display omitted] • Antimony (Sb) constitutes an ecological risk in surface water near mines in China. • Sb poses a high health risk to residents in Southern China. • The acute and chronic Sb criteria for native Chinese freshwater organisms are 511.7 and 148.3 μg/L, respectively. • The Sb drinking water guidance value to protect human health is recommended to be 19.65 μg/L for the Chinese population. [ABSTRACT FROM AUTHOR]

The residues of organochlorine pesticides (OCPs) in surface waters from Meiliang Bay, Gonghu Bay, and Xukou Bay of Lake Taihu, China, were investigated, and their ecological risks were assessed using the risk quotient method and probabilistic risk assessment. Environmental concentrations of OCPs in surface water of these bays were relatively lower compared with other rivers or lakes in China. Calculation of risk quotient associated with taxonomic groups indicates moderate ecological risks from OCPs for crustaceans and insects in these bays, while the ecological risks were low for fish and negligible for phytoplankton. The ecological risk quotients associated with individual OCPs were lower than 0.01 in these bays, suggesting a negligible risk to aquatic organisms. Ecological risk from α-HCH was relatively lower compared with DDTs, endosulfans, and γ-HCH. The combined ecological risks were evaluated using probabilistic risk assessment for only eight OCPs owing to a lack of available toxicity data for β-HCH and δ-HCH. The percentage of species with the potential to be at risk from mixture of OCPs was lower than the criteria of 5% in each bay, indicating that the combined ecological risks were acceptable. [ABSTRACT FROM AUTHOR]

The concentrations of PAHs in the surface waters from seven river basins in China were summarized from literature published from 2000-2010. Subsequently, the risks from individual PAHs and ΣPAHs in the surface waters of China were quantified by comparing the overlap between the probability distributions of exposure concentrations with the probability distributions of toxicity data. The results show that the concentrations of 15 PAHs in the surface waters ranged from 3.09 to 38139.00 ng L, with a geometric mean of 474.93 ng L. The significantly higher concentrations of the 15 PAHs occurred in the surface waters from northern China when compared with those from southern China. The concentrations of the 15 PAHs in Chinese surface waters were higher than those in other waters worldwide. The MOS (margin of safety) values were calculated at 90th percentile values of exposure concentrations and 10th percentile values of toxicity data, with 5.75, 0.17, 2.33, 0.30, 0.57, 1.74, 1.05, and 0.11 for Ace, Ant, Flu, BaP, Flua, Nap, Phe, and Pyr, respectively. The probabilities of the individual PAH concentrations exceeding the 10th percentile value of the toxicity data were 6.06%, 2.07%, 9.51%, and 2.07% for Nap, Ace, Phe, and Flu, respectively, suggesting minimal risk to aquatic organisms; however, the probabilities of BaP, Ant, Flua, and Pyr exceeding this value were 19.49%, 25.46%, 15.15%, and 30.50%, respectively, indicating potential risks. Among the individual PAHs, the ecological risk from Pyr was the highest, followed by, in descending order of risk, Ant, Bap, Flua, Phe, Nap, Flu, and Ace. Additionally, the combined ecological risk of ΣPAH8 in Chinese surface waters was significantly higher than any that of individual PAHs alone. The MOS values in the river basins were < 1, except for the Haihe River Basin, suggesting a potential combined risk from ΣPAH8 in the other six river basins. The probabilities calculation indicate that low to high ecological risk from ΣPAH8 for all aquatic species was reported in the Liaohe River Basin (65.58%), Huaihe River Basin (57.15%), Songhua River Basin (46.49%), Pearl River Basin (38.41%), Yangtze River Basin (25.98%), Yellow River Basin (15.92%), and Haihe River Basin (5.22%). [ABSTRACT FROM AUTHOR]

Zinc is a widely distributed environmental pollutants and has been listed as priority heavy metal pollutant in China. Similar as other heavy metals, toxicity of zinc to aquatic organisms affects by environmental factors such as water hardness. It is necessary to develop regional water quality criteria (WQC) to protect native aquatic life against zinc due to the diversity of aquatic organisms' variability across different water systems, as a concretization and supplement for national zinc WQC. This study derived WQC for zinc by species sensitivity distribution (SSD) curve method. The zinc toxicity data of the aquatic organisms in Taihu Lake used in SSD curve was collected based on published toxicity data for zinc with hardness values and supplemented with acute toxicity tests conducted in this study. Six aquatic organism natives to Taihu Lake were selected to conduct zinc acute toxicity test in a range of hardness conditions. The relationship between water hardness and zinc toxicity was constructed. The criterion maximum concentration (CMC) and criterion continuous concentration (CCC) for zinc in Taihu Lake were then derived, which considered the water quality and taxonomic groups in Taihu Lake. The CMC and CCC were 100.69 μg/L and 30.79 μg/L, respectively. The environmental risk of zinc to Taihu Lake are acceptable, at moderate to low levels. This study has provided a basis for regional water quality criterion derivation and risk assessment in China. [Display omitted] • Acute toxicity of zinc to aquatic organisms in Taihu Lake was investigated. • Acute toxicity of zinc reduces with the increasing of water hardness. • The criterion maximum concentration of zinc for Taihu lake is 100.69 μg/L. • The criterion continuous concentration of zinc for Taihu Lake is 30.79 μg/L. • The environmental risk of zinc to Taihu Lake are at moderate to low levels. [ABSTRACT FROM AUTHOR]