Per- and polyfluoroalkyl substances in surface water and sediment in Great Lakes tributaries and relations with watershed attributes

Per- and polyfluoroalkyl substances (PFAS) are chemicals of emerging concern that potentially pose risks to human and environmental health. In May-Oct 2018, sediment and passively collected surface water samples were collected from 62 tributary sites of the Laurentian Great Lakes with site catchments spanning various land cover types. Discrete samples of sediment collected manually and time-integrated surface water samples collected with polar organic chemical integrative samplers (POCIS) were analyzed for 23 and 34 PFAS, respectively. Concentrations of individual PFAS in sediment and surface water varied immensely among sites from below detection to 20,800 ng kg-1 and 247 ng L-1, respectively. Of all target compounds, PFOS was the most frequently detected in sediment (56 of 62 sites) and had the highest median concentration (132 ng kg-1). PFOA, PFHxS, PFOS, PFHpA, and PFNA (full chemical names are listed in online supplementary material Table S2) were detected in all 60 surface water sites, with median estimated concentrations of 5.9, 5.2, 4.6, 3.7, and 1.3 ng L-1, respectively. Compounds with 8-13 fluorinated carbons comprised a larger proportion of sediment PFAS than compounds with 4-7 fluorinated carbons, whereas compounds with 4-7 fluorinated carbons comprised a greater proportion of PFAS in surface waters. Watershed attributes, including urban land cover, airports per catchment area, and wastewater treatment plants flow percentage were significantly (p < 0.05) and positively related with PFAS sum concentrations in sediment and (or) surface water. Collectively, these results, albeit with some uncertainty in the estimated concentrations, highlight the relation PFAS occurrence has with human activities and documents widespread low-level PFAS contamination across the Great Lakes basin.