Integrated analysis of the occurrence and in situ sediment–water partitioning of selected pharmaceuticals in a riverine system

Abstract Twelve pharmaceuticals, including stimulant caffeine (CAFF), anti-inflammatories (naproxen (NPX), ibuprofen (IBU), and diclofenac (DCF)), antibiotics (anhydro-erythromycin (AETM), azithromycin (ATM), erythromycin (ETM), clindamycin (CMC), ciprofloxacin (CFC), sulfamethoxazole (SMX), and trimethoprim (TMP)), and the antiepileptic carbamazepine (CBZ), were analyzed in surface waters and sediments in the Ishmi River basin, Albania, across seasons during 2023 and 2024. This basin is characterized by limited wastewater treatment infrastructure, varying degrees of urban impact, and different environmental conditions. All targeted compounds were detected in water, with the highest concentrations observed near urban areas, particularly at the wastewater-impacted location LR1 for CAFF, IBU, NPX, and CFC with 22.5, 12.8, 2.7, and 1.8 µg L −1 , respectively. Sediment concentrations showed high levels of CFC and ATM, notably during spring with the highest concentrations of 1068 (LR1) and 396 ng g −1 (IR2), respectively, suggesting strong seasonal and spatial variability. Partitioning behavior ( K d and K oc ) was investigated in relation to compound-specific ( D ow ) and sediment-specific (pH, organic carbon, CaCO 3 and metal content) properties. Significant correlations were found, and multiple regression models successfully predicted in situ K d values for NPX, IBU, CFC, AETM, and CMC. These findings underline the influence of environmental and sediment characteristics on environmental pharmaceutical distribution.