Hydrochemical Investigations of the Rivers and Water Bodies of the Dniester River Basin in Retrospective and under Modern Conditions

摘要

The main hydrochemical indices, including ionic composition, dissolved solids content, water hardness, dissolved oxygen content, nutrients content, and the content of organic matter with regard to chemical oxygen demand (ChODMn) and ChODCr)) were investigated in the Dniester River, and also in watercourses and water bodies of its basin. It has been shown that in different sections of the Dniester River dissolved solids content increased downstream of the river, which is accounted for by the influence of both natural and anthropogenic factors. It has been found that the increase in dissolved solids content is accounted for mainly by the increase in the concentration of SO4)~(2-) and Cl~(-) ions, and also by the increase in the concentration of the sum of Na~(+) and K~(+) ions. The oxygen regime of the Dniester River is satisfactory along its whole length. However, sometimes oxygen deficiency is observed in the lower reaches of the river near its estuary, which is conditioned by the process of eutrophication. The modern state of the Dniester River in terms of the main hydrochemical indices was assessed in the sections located in different ecological regions. An effort was made to determine reference hydrochemical indices for different sections of the river.