Insights into low fish mercury bioaccumulation in a mercury-contaminated reservoir, Guizhou, China
2012
Liu, Bian | Yan, Haiyu | Wang, Cuiping | Li, Qiuhua | Guédron, Stéphane | Spangenberg, Jorge E. | Feng, Xinbin | Dominik, Janusz
We examined Hg biogeochemistry in Baihua Reservoir, a system affected by industrial wastewater containing mercury (Hg). As expected, we found high levels of total Hg (THg, 664–7421 ng g⁻¹) and monomethylmercury (MMHg, 3–21 ng g⁻¹) in the surface sediments (0–10 cm). In the water column, both THg and MMHg showed strong vertical variations with higher concentrations in the anoxic layer (>4m) than in the oxic layer (0–4 m), which was most pronounced for the dissolved MMHg (p < 0.001). However, mercury levels in biota samples (mostly cyprinid fish) were one order of magnitude lower than common regulatory values (i.e. 0.3–0.5 mg kg⁻¹) for human consumption. We identified three main reasons to explain the low fish Hg bioaccumulation: disconnection of the aquatic food web from the high MMHg zone, simple food web structures, and biodilution effect at the base of the food chain in this eutrophic reservoir.
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