APPLICATION OF ISOTOPIC ANALYSES TO STUDY THE INFLUENCE OF EXPLOITATION OF BROWN-COAL ON THE POLLUTION OF GROUNDWATER

This research deals with pollution impact on natural water resources i n the industrial area of Belchatow, central Poland, where a large brow n coal deposit is exploited and the coal is burned in an electric powe r plant. To trace the sources of groundwater pollutants the stable iso tope analysis of oxygen and sulfur in sulfates was applied. The mass-s pectrometric analysis was performed on SO42- samples from numerous wel ls and piezometres in the excavation area. By repetitive sampling perf ormed in November 1994, May 1995 and December 1996 significant changes of SO42- concentration and sulfur and oxygen isotopic ratios in sever al sites were recorded. The interpretation of isotope ratios allowed u s to recognize three groups of sulfates: (1) from the leaching of Perm ian salt dome; (2) produced by the leaching of soluble sulfates from a n ash pool and (3) produced by oxidation of natural sulfides in water- bearing rocks.