Zabokrytska M. Hydrochemical regime and water quality assessment for Zakhidnyi Bug Basin on the territory of Ukraine.

Development and implementation of methodological scheme for complex of hydrochemical investigations allowed to study in details regularities of water chemical composition forming and hydrochemical regime of transboundary river Zakhidnyi Bug ith tributaries on the territory of Ukraine on the basis of long-term and seasonal characteristics. Data obtained and coupled with identified regularities gave the possibility to highlight the leading role of natural factors in chemical composition forming of studied basin water, especially regarding to content of main ions. Applied methodological approach concerning calculations of chemical discharge has allowed estimation of the balance of matter both of natural and antropogenic origin, which have been flowed out from the territory of Ukraine (93%) and Poland (7%). Results of mean annual and seasonal distribution of absolute values and indexes of chemical discharge carried by waters of Zakhidnyi Bug Basin from the territory of Ukraine have been presented. Extraordinary role of river Poltva, on which city Lvov is located, has been determined for forming of chemical composition of Zakhidnyi Bug, mainly for upper stream. According to procedure of surface water quality ecological assessment on corresponding criterions, peculiarities of spatial and time-depending variability of the quality of water from Ukrainian part of Zakhidnyi Bug Basin have been identified.