GEOCHEMICAL ENVIRONMENT AND CHANGES IN GROUNDWATER CHEMISTRY (A CASE STUDY OF GROUNDWATER INTAKE IN LUHANSKA OBLAST)

Drinking water availability is essential for sustainable development of any country. Groundwater sources being more protected than surface ones, this determines their importance for any national economy. Providing industrially developed regions with drinking water is becoming particularly vital and crucial nowadays. Luhanska oblast is characterized by diversified economy, with processing industry being dominant. The main source of centralized drinking water supply in the region is fresh groundwater obtained from marly-chalk thickness, which quality is deteriorating. The increase in groundwater salinity is caused by an increase in sulphate and chlorides concentration in groundwater. Several hypotheses about the groundwater quality deterioration within Luhanska oblast have been proposed; however, no primary reasons have been validated yet. Since the chemical composition of groundwater depends on the composition of soils in many cases, it is relevant to study hydro-geochemical conditions of the area. The aim of the paper is to highlight geochemical processes in the geological environment and their impact on groundwater chemistry. Data from water extracts helped to reveal the ways of chemical compounds distributing with depth, and to build the graphs. In order to establish a correlation between the groundwater quality and the soil chemistry in the aeration zone there was made a map showing maximum variation in groundwater salinity within marly-chalk thickness aquifer. Spatial analysis of groundwater salinity variations was carried out based on interpolation. Quantitative data were put together by the Sturges formula. The research reveals the highest salinity to be observed in the water extracts taken from loam and clay. Spatial analysis shows the areas within which groundwater quality deteriorates. Peak values of groundwater salinity variations are confined to the areas of clay rocks in weathered crusts, while salt formations occur in unsaturated zone. Research findings helped to establish a correlation between hydro-geochemical environment and groundwater chemical composition. Research aimed at identifying the causes for changes in groundwater macrocomponent composition in marly-chalk thickness over time has practical implications for further research into groundwater quality, for the aquifers located in the unsaturated zone vicinity, namely.