A Study on the Detection Characteristics of PFOA, PFOS, and PFHxS among Perfluorinated Compounds in the Geum River Basin

The present study conducted a preliminary investigation of perfluorinated compounds (PFCs) within the Geum River Basin, focusing on potential contamination sources such as downstream areas, wastewater treatment plants, and major rivers in the basin. The targeted substances for this study were PFHxS (Perfluorohexane Sulfonate), PFOA (Perfluorooctanoic Acid), and PFOS (Perfluorooctane Sulfonate)—three PFCs that have been subjects of extensive research due to their environmental persistence and potential hazards. These substances are listed under the Stockholm Convention and are managed as water pollutants in South Korea. The findings of this study are intended to serve as foundational data for the management of PFCs in the region. A total of 15 sampling points were selected, focusing on key sites expected to influence the concentration of PFCs in the Geum River Basin, including 12 points from major downstream areas and wastewater treatment plants, as well as two tributaries (located in the middle and lower reaches of the Geum River) and one point along the main river. The three PFCs were analyzed using LC-MS/MS. Sample preparation was carried out following the water quality pollution testing standards (ES 04506.1) and the residual pollutants testing standards (ES 10390.1, ES 10363.1a). Solid-phase extraction (SPE) was performed using HLB cartridges to extract the compounds. The investigated downstream areas and wastewater treatment plants exhibited relatively high PFCs detection rates of over 94%. In some measurement points, PFOS and PFOA tended to show higher concentrations in the effluent compared to the influent. Additionally, while the concentrations in the rivers were low, below 10 ng/L, the presence of PFCs was confirmed across the entire Geum River Basin. At sites where effluent from wastewater treatment plants joined the river system, the total concentration of the three PFCs and the average concentration of PFOA were found to be the highest, indicating that wastewater treatment plants could be significant sources of PFC contamination. The concentrations of PFCs detected in the treatment plant processes were highest in the effluent from the primary sedimentation tank, followed by the effluent from the secondary sedimentation tank, influent to the secondary sedimentation tank, and influent to the primary sedimentation tank. For most substances, except for PFHxS, the concentrations in the effluent were either higher or similar to those in the influent, suggesting that PFCs were not efficiently reduced in the treatment plants, with some showing an increasing trend. This study confirmed the widespread presence of PFCs throughout the Geum River Basin. It is necessary to identify and address the major sources of these contaminants while conducting continuous monitoring to study their behavior in the environment. Furthermore, to better understand the impacts of these persistent pollutants, additional research is needed, including the analysis of various other PFCs and their precursors, beyond the commonly studied PFOS, PFOA, and PFHxS.