In Baihua Reservoir (BHR), a Hg-contaminated and eutrophic reservoir in SW China, water and sediment samples were collected in June 2010 for the determination of Hg species, metal, major ion and nutrient concentrations. Using a stable isotope tracer technique, (HgCl2)-Hg-202 and (MeHgCl)-Hg-198 were spiked into sediment cores to study methylation and demethylation processes. The inorganic Hg concentration range was 600-13,000 ng/g (dry weight, dw) in the top 10 cm of sediment; exceeding the local background concentration (260 ng/g, dw). Concentrations of Hg species in the water column and pore water were similar to non-Hg contaminated reservoirs in the same watershed. Dissolved total Hg(DHg) and dissolved methylmercury (DMeHg) (mean +/- SD) in the pore water in BHR were 6.8 +/- 3.1 and 0.27 +/- 0.20 ng/L, respectively. Dissolved Hg, DMeHg and reactive Hg (RHg) in the water column were 2.3 +/- 0.9, 0.23 +/- 0.22, and 0.77 +/- 0.17 ng/L, respectively. The vertical distributions of Hg species showed inorganic Hg and methylmercury (MeHg) concentrations peaked near the bottom of the water column, implying the impact of thermal stratification and eutrophic conditions on the production and distribution of Hg species in this reservoir. The methylation rate (<0.1%/day) in these sediments was lower and the demethylation rate (17.6%/day) was higher than those reported in other eutrophic reservoir studies. (C) 2013 Elsevier Ltd. All rights reserved.

Publication name	APPLIED GEOCHEMISTRY　Volume: 33 　Pages: 182-190　 Published: JUN 2013
Author(s)	Yan, HY; Li, QH; Meng, B; Wang, CP; Feng, XB; He, TR; Dominik, J
Corresponding author	FENG Xinbin  fengxinbin@vip.skleg.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Beijing 100864, Peoples R China.

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