Features of macro-and microelement composition and pigment characteristics of planktonic algae in lake Gusinoe during ice-сovered period

Bottom sediments of small lakes accumulate information even about small climatic changes and human economic activity in lake catchments. A comprehensive study of bottom sediments of lakes of different depths and hydrological regime, located in different landscape-climatic zones, provides the basis for different-period paleoclimatic reconstructions. The bottom sediments formation process in water bodies is determined by the differences in the intrabasin hydrodynamic, hydrochemical and hydrobiological characteristics of the ecosystem, as well as the nature and intensity of the anthropogenic load. The purpose of this work is to study the current macro-and microelement composition and the Gusinoe lake’s water mass photosynthetic activity during ice-covered period - the period without direct influence of allochtonous matter from the catchment area. The Gusinoe lake’s surface and bottom waters chemical analysis results showed that the salinity of water varied within - 392-403 mg/dm3 during ice-covered period, with large values at the surface and smaller in the bottom layer. The predominant ions in the macrocomponent composition of the lake's waters are bicarbonate-ion (211-220 mg/dm3), sulfate-ion (56-61 mg/dm3), sodium ions (51-55 mg/dm3) and calcium (28-30 mg/dm3). There is a noticeable increase in the content of sulfates and sodium ions in the bottom layer near the south-west coast at the point with the greatest depth, due to the influx of groundwater passing through the coal-bearing sediments. The content of biogenic substances during ice-covered period was minimal - nitrites, ammonium and phosphates were below the detection limit, the content of nitrates was changed in the range of 0.01-0.08 mg/dm3. 10 trace elements (Cr, Cd, Cu, Fe, Zn, Pb, Mn, Ba, Ni, Al) were determined and the highest concentrations of the sum of elements were observed in the bottom layer in the deepest place of the lake. Phytoplankton during the observation period had a high photosynthetic and production activity. This is indicated by the results obtained on the concentration of chlorophyll a, pheophytin a, Margalef index and the ratio of carotenoids/chlorophyll a, characterizing the physiological state of phytoplankton.