ECOSYSTEMS STATE OF EASTERN AND WESTERN BASINS OF SAKSKOE LAKE (CRIMEAN REPUBLIC)

Sakskoe Lake is the most thoroughly studied water body in Crimea. Its therapeutic mud and brine are exploited by balneological treatment methods. During the two centuries, when the lake was used by humans, it was subdivided into seven water bodies by dams, with two of these bodies (Eastern and Western) being now utilized for medical purposes, and the other five being protective. The Eastern (currently exploited) basin is now used to produce therapeutic mud and brine. The bottoms of the saline basins are covered by sediments: an upper layer of black silt, which is underlain by gray, steel-gray, occasionally bluish silt, which is used as therapeutic mud. The lake is fed by surface and groundwaters. Retaining dams and flood embankments erected in nearby ravines preclude desalination of the lake with flood and rain waters. Seawater is pumped to the lake through channels to preclude its drying. A quay is now actively constructed around the lake and will likely notably affect its hydrological and ecological conditions. The aim of the present study was the comparative analysis of the chemical and physical characteristics of the Eastern and Western basins of the Sakskoe Lake at the period of intensive building activity on their coasts at the summer period of 2019. Brine samples were collected at two tested sites in each of the lakes. Water salinity was measured by a PAL-06S LTA GO (Japan) refractometer and was expressed in ‰. The pH and Eh of the waters and oxygen dissolved in them were determined in the laboratory by an Expert-001 (Econix-Expert Moexa CoLtd, Russia) analyzer, with the use of appropriate Volta (Russia) selective electrodes. Ions concentration was determined spectrophotometrically and by atomic absorption method. Various living stages of Artemia populations in two water bodies were studied according the standard microscopic methods. The obtained results demonstrated, that the total content of the cations in the brine of the Western basin was in 1,5-fold higher as compared with the data of the brine in the Eastern basin (108,4 and 71,2 g/l respectively). The values were directly correlated with the high salinity of the Western basin brine. The identical trend was shown for the anions concentration, which was significantly greatly in the Western basin related to Eastern one (193,14 and 125,41 g/l correspondingly), which was connected with the different hydrogeological conditions of the formation of the ecosystems of the tested water bodies. At the other hand, pH, salinity and Eh of the brine in the Eastern basin were lower than in the brine of the Western basin, while the concentration of dissolved oxygen was higher. In the brine of the Eastern basin of the lake all living stages of Artemia, including cysts, nauplia and adults were found, while in the Western basin only cysts were shown. Therefore, according the obtained results we could suggest, that anthropogenic processes which were taken place on the coasts of the Sakskoe Lake accompanied with the intensive building activity did not influence on the lake ecosystem. The further monitoring studies including the testing of the ions concentrations in the brine of two basins, Artemia populations state are required for the understanding the changes of the both ecosystems and the possible reasons of their changes. It is important for development of the optimization of the management of Sakskoe lake and its resources exploitation.

The chemical composition of glacial melt water ponds and streams on the McMurdo Ice Shelf, Antarctica

Melt waters cover c. 20% of the McMurdo Ice Shelf during the austral summer. The streams, ponds, and lakes up to 104 m2 in area occur in two types of terrain systems with differing morphological, chemical, and biological characteristics: pinnacled ice (PI) areas with sparse sediment cover, low relief, and little biomass; and ice-cored moraine (ICM) areas with 10–20 cm sediment cover, hummocky topography with up to 20 m relief, occasional mirabilite deposits, and dense benthic cyanobacterial mats. Pond water composition in the two areas is markedly different. PI area melt waters have low salinities, <2270 mg 1−1 total dissolved salts (TDS), and near neutral pH, mean = 7.8. The chemical composition of PI waters closely follows that of diluted sea water, suggesting that the release of ions from the sea ice matrix of the ice shelf is the major solute source. In contrast, ICM area melt waters have a wide range of salinities, up to 60 400 mg 1−1 TDS and alkaline pH, mean = 9.3. The chemical composition in c. 40% of the ICM ponds investigated did not resemble that of sea water, but had higher relative abundances of SO2−4, Na+, K+ and Ca2+. Leaching of local salt deposits, particularly mirabilite, weathering of surficial sediments, and morphological features promoting closed-basin brine evolution are possible contributing factors to the enrichments.

Gamma and Alpha Radiolysis of Salt Brines

Gamma radiolysis of Permian Basin brine leads to equilibrium gas pressure of about 100 atm. at 75°C and about 40 atm. at 150°C, providing the gas space is very small and/or the total dose is very high. Dose rate dependence is being investigated but is not yet established. Alpha radiolysis of Permian Basin brine is still being evaluated, but it is clear that equilibrium gas pressures will be much higher than with gamma radiolysis. In addition, alpha radiolysis of brine results in a very high solution redox potential. Gas compositions in all cases have been about two parts H2 to one part O2. Efforts to simulate these results with computer models have been quite successful.