Гидрохимический состав и стратификация воды в пойменном озере Тахтарка

Abstract

The Takhtarka Lake, a floodplain lake in the Don River basin, was studied in the summer months of 2005, 2007, 2008 and 2016 and in winter of 2018. Great vertical differences of water salinity, up to 0.5 g L-1, existed in the lake in summers, as well as gradients of redox potential, sulfide concentrations (>2 mM in bottom layer) and biogenic elements, which are rather characteristic for euxinic meromictic water bodies. Nevertheless, calculations have shown that meromictic stability in the lake is not sufficient for reliable suppression of its full overturn in the autumn period. Winter observations in 2018 confirmed this conclusion. Thus, in hydrochemical terms the lake appeared to be a highly dynamic system with significant vertical gradients of environmental conditions formed and destroyed annually or almost annually. In general, the lake can be apparently attributed to an uncommon and insufficiently studied group of lakes with «spring meromixis» and «irregular mixing» regime.