Zróżnicowania tła hydrogeochemicznego wód podziemnych eksploatowanych na terenie środkowej i północnej Polski

Abstract

VARIATION OF HYDROGEOCHEMICAL BACKGROUND OF SUBSURFACE WATERS IN CENTRAL AND NORTHERN POLAND Summary A hydrochemical background understood as the concentration of hydrochemical elements typical for a studied hydrogeological unit, is considerably varying in drinking waters of Northern and Central Poland (Tables I-V). Such variation is of regional type and still mostly connected with vertical zones of water-bearing beds. The variation of a hydrogeochemical background is due to natural conditions of occurrence and circulation of underground waters as well as anthropo-pressure that changes a chemical composition of underground waters and particularly, of ground waters. The anthropo-pressure transformed a hydrogeochemical background of ground waters in many areas of the country whereas deep waters do not indicate any chemical transformation, except from intensively used (urban-industrial, farming) areas. Maximum limits of hydrogeochemical background in non-polluted waters are generally beneath the standard values for drinking waters. Iron and manganese are the only exceptions as they commonly occur in larger amounts. Slightly polluted waters have concentrations of individual components still below the standard values but however higher than the upper limit of the natural hydrogeochemical background of a given unit. The earliest anthropogenic changes are noted in the case of microcomponents, nitrates, sulphates, chlorides and dry remnants. In such cases finding the initial anthropogenic phases of hydrogeochemical transformations is possible due to a comparison of the natural hydrogeochemical background of waters in a studied area, or of any other similar (in hydrogeochemical sense) area, with concentrations determined in individual analyses. These remarks indicate a possible vast use of studies of a hydrogeochemical background for finding the first phase of underground water pollution.