Chemical characteristics of antarctic lakes of the Thala Hills

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The article presents the results of measurements of the principal ions content, electrical conductivity and pH for 13 lakes and small (temporary) water ponds in the east part of the Thala Hills, Enderby Land, East Antarctica. Water sampling was carried out by participants of the seasonal Belarusian Antarctic expeditions in the period from 2011 to 2018. The purpose of the study is the evaluation of the hydrochemical composition of lakes and temporary ponds of the Thala Hills (on an example of the Vecherny Oasis), identification of natural and anthropogenic factors which determine the variability of the hydrochemical parameters for assessment of vulnerability of lakes and temporary ponds to anthropogenic impacts and climate change. It is shown that the waters of the lakes of this region are low mineralized with the sum of ions within the range of 10.6–87.5 mg/l (the average is 34.5 mg/l), electrical conductivity — 19.3–130.0 μS/cm (61.3 μS/cm). The water is characterized as slightly acidic and neutral. The waters of small (temporary) ponds are characterized by greater variability of hydrochemical parameters in comparison with lakes: the sum of ions is in the range of 6.7–915.0 mg/l (the average is 158.0 mg/l), the electrical conductivity is 4.6–1663.0 μS/cm (the average is 267.0 μS/cm). Coefficients of variation for most compounds in the waters of temporary ponds exceed 100 %. In most cases the predominance of sodium and chloride ions was established, which indicates the influence of marine aerosols on chemical composition of water lakes and temporary ponds. Elevated concentrations of mineral elements in the water of temporary ponds are caused by the lack of flow and, and as a consequence of thies, the accumulation of salts as a result of evaporation.