| Abstract [eng] |
Groundwater in Western Lithuania is distinguished by lower water hardness. Water hardness is characterized by calcium and magnesium compounds dissolved in water. The formation comparisongly of low water hardness in western Lithuania is associated with the mixing of fresh and sea water due to the sea trangression and the filtration of fresh rainwater through glauconitic deposits, which are rich in sodium and potassium. Glauconite tends to give off potassium and sodium during cation exchange and take calcium and magnesium from groundwater. Glauconite - quartz sand is widespread in almost the entire study area, but the amount of glauconite in that layer is very unequal. Mostly glauconit is 10% in some places up to 20%. In 1993 was performed the research which showed that the most promising areas were identified in Barzdėnai and Žemaičiai Naumiestis, where the glauconite content in the rocks exceeds 20%. In western Lithuania, the groundwater of the Lower Cretaceous is characterized by a higher content of chloride in the water, because in this part of the river valleys due to occurring pahways saltier sodium chloride water flows from older aquifers. The curren study shows that Cretaceous and Jurassic groundwater is saturated with carbonate minerals aragonite, calcite, and dolomite. Their saturation is higher in the eastern and northern part of the study area, and lower saturation of these minerals around Šilutė, Rusnė, Žemaičių Naumiestis, Barzdėnai, where the concentration of glauconite in rocks is higher. Mineral halite and silvin saturation is higher near the Baltic Sea and in the southern part of the study area. |
