The differentiation of pharmaceutical concentrations at two river bank filtration sites located in Warta River valley (Poland) - preliminary results

Emerging contaminants (e.g. pharmaceuticals, personal care products, drugs or pesticides) are increasingly detected in aquatic environments. The most apparent contamination source of river water pollution by pharmaceuticals are sewage treatment plant stations that discharge treated sewage effluent to the rivers. The river bank filtration systems (RBF) can effectively remove these contaminants from polluted river waters. The two RBF sites were examined for pharmaceuticals occurrence that are located in the Warta River valley (Poland): Śrem waterworks located upstream and Gorzów waterworks located downstream from Poznan city. The water samples for pharmaceuticals investigation (114 substances in total) were taken from the river and from four continuously pumped wells in each site. Two wells at a close distance from the river were chosen at each site (40-50 m) and two wells located at a greater distance from the river (70 m in Śrem and 110 m in Gorzów). A visible increase in pharmaceutical concentration was observed in the river water. The sum of pharmaceuticals concentration is 8151 ng/l in the Śrem location, while in the Gorzów location, the sum of pharmaceuticals concentration is 9142 ng/l. Most probably, this increase is caused by the influence of treated sewage effluent from Poznań city and towns and villages located along the river. A considerable differentiation in pharmaceuticals removal rate was observed. In the Śrem site the sum of pharmaceuticals concentration in wells is between 657 ng/l and 3290 ng/l, while in the Gorzów site despite the higher concentrations of pharmaceuticals in the river, the pharmaceuticals were detected only in one well located at a close distance from the river (two substances at a total concentration of 92 ng/l). The research presented proves a very different rate of pharmaceuticals removal even on sites located at similar hydrogeological conditions and demonstrates the necessity of its monitoring, especially in groundwater that is strongly influenced by river water contamination (like RBF sites). This work has received funding from the National Science Centre of Poland (grant no. 2021/41/B/ST10/00094).