HYDROCHEMICAL AND MICROBIOLOGICAL CHARACTERISTICS OF MINERAL LAKES IN SOUTHWESTERN TRANSBAIKALIA
V.V. Khakhinov1, E.V. Lavrentyeva1,2, I.D. Ulzetueva3, D.D. Tsyrenova2, S.V. Zaitseva2, D.D. Barkhutova2
1Buryat State University, Ulan-Ude, Russia
2Institute of General and Experimental Biology, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, Russia
3Baikal Institute of Nature Management, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, Russia
Keywords: saline lakes, mineralization, microorganisms, sulfate reduction, methanogenesis, toxicity index
Abstract
The article considers the results of hydrochemical and microbiological studies of four largest mineral lakes in southwestern Transbaikalia: Nizhnee Beloe, Verkhnee Beloe, Tsaidam and Selenginskoe (Sulfatnoe). It is revealed that the processes of formation of the chemical composition of lake waters are mainly related to the geostructural features of the territory, hydrogeochemical processes and climatic conditions. It is concluded that the chemical composition of water is greatly influenced by evaporation associated with high solar insolation in the region, the process of water freezing in winter and the inflow of atmospheric precipitation. The anionic composition is dominated by hydrocarbonate, chlorine and sulphate ions, while among cations the leading place belongs to sodium ions. It was found that alkalophilic and halophilic bacteria-destructors are widespread in these lakes, and their activity influences the formation of water composition in such lakes. A quantitative assessment of the microbial process rates showed that the rate of oxygenic photosynthesis in these lakes amounted to 331-680 mg С/(m2 day), and the rate of anoxygenic photosynthesis was within the range of 24-500 mg С/m2. The rate of dark fixation ranged from 30 to 776 mg С/(m2 day). It has been shown that sulfate reduction is the key terminal destruction process in the lakes. In the bottom sediments and microbial mats of the lakes, most of the organic matter is utilized for sulfate reduction. The high abundance of cellulolytic and amylolytic microorganisms indicates the input of allochthonous organic matter into the lakes. These data in comparison with the number of sulfate-reducing bacteria in the lakes allow us to speak about the water bodies as experiencing anthropogenic impact. Trends of changes in these characteristics of lake waters as a result of natural evolution and anthropogenic impact are established.
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