Sulfur and chlorine compounds in water bodies of the Pymvashor subarctic hydrothermal system

The results of the study of the behavior of redox-dependent sulfur and chlorine compounds in sediments of water bodies of the Pymvashor natural boundary (PNB) located in the Bolshezemelskaya Tundra (the Polar Cis-Ural Region, Nenets Autonomous Okrug, Russian Federation) are presented. Currently, the Pymvashor is the only known location in Continental Europe where hydrothermal springs function in the polar territories. Data on the quantitative characteristics of the geochemical parameters of bacterial sulfate reduction (reduced sulfur compounds, reactive iron forms, and organic matter) in the sediments of all studied Pymvashor water bodies have been obtained. It has been established that the revealed differences in the distribution and transformation of these parameters, in addition to the main reasons affecting the course of redox processes, were also caused by the thermal factor (warming effect of thermal waters on all ecosystems of the natural boundary). Thus, iron monosulphides dominated in the upper sediment layers of non-freezing watercourses, which distinguished them from the sediments of seasonally frozen lakes, where sulfur associated with organic matter dominated along the entire length of the sediment cores. The presence of chlorophenols (CPs) and their derivatives, including pentachlorophenol as a persistent organic pollutant, in the sediments of studied Pymvashor water bodies was established. It is shown that the chlorophenol composition is mainly induced by the occurrence of natural enzymatic and biochemical processes. The influence of microclimatic conditions of the subarctic hydrothermal system on the composition, levels, and distribution of chlorophenolic compounds in the sediments was revealed.