Identyfikacja procesów kształtujących skład chemiczny wód podziemnych poniżej torfowiska-Pożary, Kampinoski Park Narodowy

The aim of this study was to identify hydrogeochemical processes controlling chemical composition of groundwater of the existing peatland. The site of the study is located within the Pożary Special Protection Area of the Kampinos National Park. Lithological profilem consists mainly of varigrained sand, covered by organic matter constituting peatland. The groundwater table fluctuates between 0.6 m below and 0.3 m above ground level. Combination of high organic content of soil profile and shallow depth to the water table causes slightly reducing conditions, especially in the upper part of aquifer. There, oxidation of organic matter (and/or methane) as well as nitrate and sulphate reduction has been presumed while denitrification and/or dissimilatory nitrate reduction to ammonium (DNRA) seems to control chemistry of groundwater in deeper part of the profile. The important differences in the chemical and isotopic composition of dissolved carbon have been found in the depth profile. Carbon isotopic composition of dissolved inorganic carbon in groundwater (13CDIC) indicates that carbonate carbon is derived mostly from the decomposition of organic matter, a small contribution being derived from the dissolution of carbonate minerals. The contribution of atmospheric CO2 to chemical and isotopic composition of dissolved carbon is negligible within all parts of aquifer.