Mercury (Hg) along with other trace metals and nutrients in the Arctic regions are good indicator of exogenous pollution. The increase level of these contaminants affects microbial community and ultimately influences various biogeochemical cycles. This work assessed the contents of total mercury (THg), methylmercury (MeHg), different trace metals, and various other nutrients along with exploring microbial composition in the sediments collected from 10 different sites of East Siberian Sea of Arctic regions. The THg and MeHg contents ranged from 43.2 to 85.5 µg/kg and 0.19 to 0.76 µg/kg, respectively. Notable levels of Al, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Cd, and Pb were detected in whole sediment and porewater collected from all the sites. The average total organic carbon (TOC) was 1.4%. The concentrations of NO3-, SO42-, and NH4+ in porewater were 0.05–0.12 mmol/L, 14.8–30.3 mmol/L, and 0.12–0.53 mmol/L, respectively. The distribution of Hg correlated with various trace metals and nutrients levels which indicated exogenous contribution of pollutant in the Artic region. The microbial composition analysis found that Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, and Chloroflexi as dominant bacterial phyla, whereas Thaumarchaeota and Euryarchaeota were established as major archaeal phyla in all the sediments. However, the relative abundance of these phyla varied among various sites, implying that presence of Hg along with other trace metals and nutrients affects both bacterial and archaeal communities. In overall, the multi-component geochemical data presented in this study along with profiling of microbial composition facilitate to understand the anthropogenic inputs on the Arctic environment and ecosystem.

Distribution of mercury and other trace metals along with profiling of microbial composition in the Arctic sediment

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