FORMOWANIE SKŁADU CHEMICZNEGO WÓD PODZIEMNYCH W WARSTWACH MIOCENU I PLEJSTOCENU REJONIE WYSTĘPOWANIA GŁĘBOKIEJ DOLINY KOPALNEJ W POBLIŻU WYSOKIEJ (POJEZIERZE KRAJEŃSKIE)

Abstract

THE FORMATION OF CHEMICAL COMPOSITION OF GROUNDWATERS FROM THE MIOCENE AND PLEISTOCENE AQUIFERS WITHIN OF THE BURIED VALLEY NEAR WYSOKA (KRAJEŃSKIE LAKE DISTRICT)Abstract. The analysis of chemical composition variability of the Miocene aquifer groundwater during the groundwater flow through the buried Pleistocene valley is presented in the paper. The study area is located in northern Wielkopolska, where the homogeneous Miocene aquifer was found over a wide area. This aquifer is intersected by the buried valley located in the vicinity of Wysoka. The deep Pleistocene and Miocene aquifers are found in hydraulic connection within the buried valley area. Taking into account the dissimilar formation conditions of the hydrogeochemical environment, three zones were distinguished: the Miocene aquifer preceded the buried valley (A zone), the deep Pleistocene aquifer within the limits of the buried valley area (B zone), and the Miocene aquifer beyond the buried valley (C zone). The deep Pleistocene aquifer groundwater (zone B) within the buried valley area was found to contain evidently high concentrations of chloride and sulphate ions. Maps of Cl– and SO42– concentrations were made without interpolation using the point kriging method. The incerease of the concentrations in the deep Pleistocene aquifer (zone B) is due to an ascent from the Mesozoic aquifers. The changes in water hardness and alkalinity of the deep Pleistocene aquifer in the research area may be related to the change in redox potential conditions and decomposition of organic matters. A set of factors (F 1, F2 and F3) affecting the chemical composition of groundwaters was distinguished as a result of the factor analysis. The identified processes which affected the chemical composition of the Miocene and deep Pleistocene aquifers are of natural geological character and are associated with the current groundwater flow system.