PHYSICO-CHEMICAL CONTROL OF LAKE SEVAN WATER QUALITY

Introdoction. The high-altitude lake of the Caucasus – Sevan, is a natural source of water for the population and agricultural lands, including areas for growing medicinal plant raw materials. Against the background of anthropogenic impact, there is active development of phytoplankton and cyanobacteria, as well as exceeding the normative values of heavy metals in both the Large and Small Sevan lakes. Objective of the study – to apply physicochemical methods of analysis, used in pharmacopoeial analysis, to assess the water quality of Lake Sevan. Material and methods. Water quality monitoring of Lake Sevan was conducted using electrochemical methods (conductometry and potentiometry), water dispersity was evaluated using dynamic light scattering (DLS), the content of essential elements and heavy metals was determined (X-ray fluorescence analysis – XRF), and potentially toxic organic compounds were investigated (IR spectroscopy and HPLC-MS, GC-MS). Results. The average values of specific electrical conductivity and the corresponding concentrations of standard salt solutions indicate the absence of statistical differences for waters of different seasons, i.e. they do not depend on temperature fluctuations and the environmental load on the lake. The waters of Lake Sevan have a pH of 8.6–8.9. The waters are characterized by polydispersity with maxima at 164 nm and in the range from 255 to 342 nm. The IR spectra of the residues after water removal demonstrated the presence of organic compounds of different classes, the content of which is higher in summer. Traces of potentially toxic compounds were detected using the chromatographic method. Inorganic components are ranked by content: Cl (2.3%) > K (0.7%) > S (0.5%) > Ca (0.41%) > Br (107 ppm) > Zn (38 ppm) > Fe (23 ppm) > Mn (6.2 ppm) > Cu (2.1 ppm). Conclusions. The analysis of water samples from Lake Sevan in summer and winter demonstrated the feasibility of monitoring their quality using pharmacopoeial physicochemical methods. Lake Sevan is a sustainable ecosystem that requires careful management to avoid its negative transfor-mation