The impact of treated wastewater effluent on contamination of a water supply aquifer during one decade of water exploitation (Tursko well field, Poland)

The recharge zone of an aquifer supplying the Tursko well-field (Poland), located in an area of sparse water resources, shows groundwater contamination manifested by high nitrate concentrations and pharmaceutical compounds. This study documents the steady deterioration of groundwater chemistry during one decade of groundwater exploitation, and analyses wastewater impact on the groundwater chemistry using pharmaceutical compounds as anthropogenic tracers, with focus on the influence of treated wastewater and drainage water. These waters infiltrate into groundwater from a drainage ditch located in the water supply aquifer’s recharge zone. It is shown that strongly contaminated water can deliver organic matter and nutrients to the groundwater, activating or intensiying denitrification. As a result, the nitrate concentration has decreased in the groundwater, while concentrations of denitrification products have increased. Associated process of oxidation of organic matter causes periodic exceeding of limits allowed for drinking water. The ability of pharmaceutical compounds to act as anthropogenic tracers shows that infiltration of wastewater is a significant factor influencing drinking groundwater quality.