Submarine groundwater discharge as a source of pharmaceutical and caffeine residues in coastal ecosystem: Bay of Puck, southern Baltic Sea case study.

Even though the occurrence of pharmaceuticals in the water environment is thought to be a potential problem for human health and aquatic organisms, the level of knowledge of their sources and presence in the marine ecosystem is still insufficient. Therefore, this study was designed to determine the emergence of sixteen pharmaceuticals and caffeine in groundwater, submarine groundwater discharge (SGD), rivers and coastal seawater in the southern Baltic Sea. It has been recognized that chemical substances load associated with SGD can affect coastal ecosystems equally or even greater than surface runoff. Hence, the Bay of Puck, which is an active groundwater discharge area, has been chosen as a model study site to assess the preliminary risk of pharmaceutical and caffeine residues supply in coastal ecosystem. A special focus was placed on tracing the possible sources of pollution for groundwater and SGD based on the composition of collected samples. Five pharmaceuticals (carbamazepine, sulfapyridine, sulfamethoxazole, ketoprofen and diclofenac) and caffeine were detected in varying concentrations from below the detection limit to 1528.2 ng L. Caffeine and diclofenac were the most widespread compounds. Groundwater was mostly enriched in the analysed compounds and consequently SGD has been recognized as an important source of identified pharmaceutical and caffeine residues to the Bay of Puck. A predicted no-effect concentration (PNEC) was determined in order to perform an environmental risk assessment of five pharmaceuticals and caffeine detected in water samples. Finally, future challenges and potential amendments in monitoring strategies are discussed.