Spatial And Temporal Assessment Of Organic Micropollutants In The Pra River Basin

Abstract

The extensive occurrence and potential harmful impacts of per- and polyfluoroalkyl substances (PFAS) and polychlorinated biphenyls (PCBs) have garnered considerable attention. The presence of these organic micropollutants pose threat to river bodies and their sustainability. This study aims to determine the levels and distribution of PFAS and PCBs, in the Pra River basin. A total of 20 sampling points were selected to collect water and sediment samples, covering both upstream and downstream locations along the river. Solid Phase Extraction (SPE) was employed for pre-concentration and pre-cleaning of samples prior to analysis. Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) techniques were employed to analyze water and sediment samples for targeted PFAS and PCBs. The results revealed extensive presence of PFAS and PCBs in the Pra River basin. Multiple PFAS compounds, including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonic acid (PFOS) were detected at varying levels across all the sampling points with a range between 14.5-112.4 ng/L for water samples and 55.9-186.5 ng/g for sediments. Similarly, total PCB level ranged between 0.53 and 5.87 ng/L for water samples and 2.60-139.79 ng/g for the sediment samples. PCBs 138, 149, and 153, were identified as most dominant in the river basin. The human health risks associated with exposure to PFAS and PCBs through surface water and sediment were negligible. Decomposition of perfluorooctanoic acid (PFOA) by water radiolysis led to defluorination efficiency of 98% with solvated electrons and carbon dioxide radical anions being primary reactive species. These findings indicate that the Pra River basin is contaminated with PFAS and PCBs.