Mercury species in zooplankton, brine, and bottom sediments of hyperhaline Lake Bolshoye Yarovoye (south of Western Siberia)

The investigation focused on examining the concentration of mercury in the brine, plankton, and bottom sediments of Lake Bolshoye Yarovoye. Mercury in inorganic complexes primarily exists in the forms of HgCl₄^2– and Hg(SR)₂. Within lake and pore waters, mercury will be present as MeHgSR-DOM rather than MeHgCl. Accumulation of mercury in bottom sediments ensues from the precipitation/dissolution processes oxides and oxyhydroxides of Fe and Mn. The geochemical behavior of mercury in sediments is subject to the influence of various sulfur compounds, including S (VI), S (II), S⁰, and pyrite, which possess the capacity to constrain the bioavailability of mercury and impact the formation of MeHg. A correlation is noted in the distribution of Hg-OM and S (II) within the upper 50 cm of sediment. The vertical migration of technogenic mercury in the sediment core due to its high water content has been identified. At a depth of 110–120 cm, a geochemical barrier emerges, characterized as a zone of active transformation of mercury forms. A moderate level of mercury contamination has been observed in bottom sediments and plankton Artemia salina within the influence zone of the “Altaikhimprom” plant.