Agresywność chemiczna płytkich wód podziemnych Wrocławia

Abstract

Chemical aggressiveness shallow groundwater in A b s t r a c t. Evaluation of the chemical aggressiveness of shallow ground - water for the area of Wrocław was performed in accordance with the Polish Standard (PN-EN 206+A1:2016-12). This standard requires determination of pH and concentration of ammonium, magnesium, sulphate and aggres sive carbon dioxide in water. The research was carried out on 96 ground - water samples collected in the period March–May 2021 from Holocene, Pleistocene and Neogene deposits. The results show that 58% of shallow groundwater in Wrocław was aggressive towards concrete and steel. The slight (XA1), moderate (XA2) and high (XA3) aggressiveness was charac - teristic for 32%, 23% and 3% of the analysed waters, respectively. The significant classification factors were the concentrations of aggressive carbon dioxide, sulphate ions and, less significant, pH. The presence of magnesium and ammonium ions in groundwater did not have any classification significance because of low concentrations. The occurrence of aggressive groundwater is associated with the environment of river sediments, mainly of Holocene and Pleistocene age. Groundwater beneath till and clay formations, mainly of Pleistocene age, and of anthropogenic banks and dumps shows significantly lower aggressiveness. Aggressiveness of groundwater sampled from the aquifer covered by Neogene clay deposit is not demonstrated. The aggressiveness of Wrocław groundwater shows a mosaic space character resulting from the geological structure of the city’s subsurface formations and is probably also related to the form of land development. The most aggressive ones were associated with green, agricultural and liquidated municipal waste dump areas.