Per- and polyfluoroalkyl substances (PFAS) in the rivers of the Western United States

Per- and polyfluoroalkyl substances (PFAS), commonly referred to as “forever chemicals” raise significant concerns due to their persistence, bioaccumulation potential and toxicity. However, there is limited information on the occurrences of PFAS in surface water in the Western United States. In this study, the occurrence, source apportionment, and ecological risks were investigated for PFAS in 16 rivers. Liquid Chromatography / Tandem Mass Spectrometry (LC/MS/MS) was utilized to identify and quantify PFAS compounds. Perfluorooctanoate (PFOA) and Perfluoroheptaoinc acid (PFHpA) were consistently detected as the principal PFAS in rives. For PFOA, the contamination levels were significantly greater in The Gila, Los Angeles, San Juan and Santa Cruz rivers. Conversely, the Boise, Clark Fork, Columbia, Truckee and Willamette rivers exhibited lower median PFOA levels. PFHpA was detected in the Truckee River at concentrations ranging from less than the limit of quantitation (LOQ) to 26.3 ng L⁻¹. The relationships among PFAS compounds were investigated by principal component analysis (PCA) using Varimax rotation with Kaiser normalization. For the Boise River, three factors were extracted by PCA and PC2 was dominated by PFOA and PFNA with rotated component matrix values of 0.897 and 0.779, indicating fluorotelomer alcohol degradation as an important source of these compounds. This study provides additional information to better understand PFAS contamination in aquatic environments.