Occurrence of pharmaceuticals and risk assessment in urban groundwater

Due to the fast urbanization and climate change, urban aquifers are considered as a strategic source of potable water. However, a potential limitation is the presence of contaminants, such as pharmaceuticals, which might deteriorate groundwater quality. This work investigated the occurrence of pharmaceuticals and evaluated their human health risk in an alluvial urban aquifer recharged by a polluted river that receives discharges from wastewater treatment plants (WWTPs). To this end, river and groundwater samples were collected from February to May 2021 for the analysis of 92 pharmaceuticals using a solid-phase extraction and a highpressure liquid chromatography coupled to a high resolution mass spectrometric methodology (HPLC-HRMS). Results showed that 35 pharmaceuticals, including 6 transformation products (TPs), were detected in all groundwater samples and the range of concentrations was from the low ng L-1 to 44.5 μg L-1. Moreover, the concentrations of some substances decreased along the flow path during bank filtration, suggesting the occurrence of natural attenuation processes (e.g., adsorption or oxidation-reduction). Finally, most of the measured substances did not pose a risk to human health since estimated risk quotients were low.This research has been supported by the Ministerio de Ciencia e Innovación (grant no. CEX2018-000794-S). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe