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Formation and distribution of methylmercury in sediments at a mariculture site: a mesocosm study |
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| Authors: | Peng Liang Cheung-Lung Lam Zhang Chen Hong-Sheng Wang Jian-Bo Shi Sheng-Chun Wu Wen-Xiong Wang Jin Zhang Hailong Wang Ming-Hung Wong |
| Institution: | 1. School of Environmental and Resource Sciences, Zhejiang Agricultural and Forestry University, Lin’an, Zhejiang, China 2. Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong, People’s Republic of China 3. China Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China 4. Section of Marine Ecology and Biotechnology, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China |
| Abstract: | PurposeThe aim of the present study was to investigate the differences of methylmercury (MeHg) formation and distribution between mariculture (aquaculture) sediments (MS) and reference sediments (RS) collected from a site in Hong Kong.Materials and methodsThe MS and RS samples were split into four batches, three of which were spiked with HgCl2 aqueous solution to a concentration of 0.8, ,2 and 8 mg k g?1 in sediment samples SP1, SP2, and SP3, respectively, while the rest served as a control batch (referred to as C).Results and discussionThe results showed that the highly Hg-polluted sediment produced greater amounts of MeHg. During the culture period, MeHg concentrations in sediments decreased over time. The decreasing percentage increased in the order of SP3?<?SP2?<?SP1, which might be due to the inhibition of MeHg degradation by high Hg concentrations. The mean value of MeHg concentrations and %MeHg of the total Hg (THg) in MS was significantly lower than those in RS, possibly due to the complexation of Hg with organic ligands, leading to lower Hg bioavailability for methylation bacteria. The distribution coefficient of THg (KdT) was relatively high in MS compared to RS, indicating that the former had a greater number of binding sites for Hg adsorption.ConclusionsMethylmercury formation was inhibited in MS, probably due to increased complexation of Hg2+ with organic matter and adsorption of Hg to MS. Furthermore, the mean value of KdT in MS was relatively high when compared to RS, which illustrates that MS sediments have more binding sites than RS for adsorption of Hg. |
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