☆ 4.7 Article

Mercury speciation, bioavailability, and biomagnification in contaminated streams on the Savannah River Site (SC, USA)

SCIENCE OF THE TOTAL ENVIRONMENT (2019)

期刊

SCIENCE OF THE TOTAL ENVIRONMENT

卷 668, 期 -, 页码 261-270

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ELSEVIER SCIENCE BV

DOI: 10.1016/j.scitotenv.2019.02.301

关键词

Mercury; Speciation; Methylation; Bioavailability; Biomagnification; Diffusive gradients in thin films

类别

Environmental Sciences

资金

Area Completion Project program of Savannah River Nuclear Solutions through the U.S. Department of Energy [DE-EM0004391]

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摘要

Water, sediment, and biota from two streams on the Savannah River Site were sampled to study mercury (Hg) biogeochemistry. Total and methyl- Hg (MHg) concentrations were measured for all samples, speciation models were used to explore Hg speciation in the water, and Diffusive gradients in thin films (DGT) were applied to indicate the vertical profiles of labile Hg (DGT-Hg). Trophic position (delta N-15) was estimated for biota and used to establish MHg biomagnification model. The speciation model indicated Hg methylation in the water occurred on settling partides and the most bioavailable Hg species to bacteria were complexes of inorganic Hg and labile organic ligands. Correspondingly, dissolved organic carbon concentrations were positively related to MHg concentrations in the water. In the sediment, the sharp increase of DGT-Hg around the sediment water interface underscores the importance of this interface, which determines the differences in the accumulation and generation of labile Hg among different waterbodies. The positive correlation between sediment MHg and sulfate concentrations suggested possible methylation reaction by dissimilatory sulfate reducing bacteria in the sediment. The food web magnification factors of MHg were 9.6 (95% CI: 4.0-23.4) and 4.4 (95% CI: 2.5-7.7) for the two streams established with trophic data of biofilm, invertebrates, and fish. Meanwhile, DGT-Hg concentrations in the water were positively correlated to biofilm Hg concentrations, which can be combined with the MHg biomagnification model to generate a modified biomagnification model that estimate MHg bioaccumulation with only labile Hg concentrations in the water. With this approach, Hg accumulation in abiotic and biotic environmental compartments was connected and the different bioaccumulation patterns of Hg in different waterbodies were explained with both geochemical and biological factors. (C) 2019 Elsevier B.V. All rights reserved.

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Appraising ecotoxicological risk of mercury species and their mixtures in sediments to aquatic biota using diffusive gradients in thin films (DGT)

Yang-Guang Gu, Hong-Hui Huang, Shi-Jun Jiang, Xiu-Yu Gong, Xiu-Li Liao, Ming Dai

Summary: This study assesses the integrated toxicity of mercury species mixtures in sediment using the DGT technique in Daya Bay. The results indicate that both inorganic mercury and methyl mercury in the sediments exceed the risk threshold and have adverse effects on aquatic biota. However, the probabilistic biological risk assessment shows that the toxicity probability in Daya Bay's sediments is low.

SCIENCE OF THE TOTAL ENVIRONMENT (2022)