55 / 2024-09-03 18:17:19

Molecular characteristics of emerging perfluoroalkyl and polyfluoroalkyl substances (PFAS) and dissolved organic matter (DOM) in surface waters around fluorine related industries in a Chinese Megacity

Nontarget and suspect,F-containing DOM,IPFAA,F/C values

Fluorine-related industrial discharges are the main source of per- and polyfluoroalkyl substances (PFAS) contamination in surrounding surface waters, but the long-term environmental impacts of their residual PFAS and the interactions between PFAS and dissolved organic matter (DOM) in field waters have rarely been discussed. In this study, concentrations of 32 target PFAS were quantified, 50 nontarget and suspect PFAS were identified and semi-quantified, molecular characteristics of DOM were analyzed in the surface water of Shanghai, a metropolis in China where the fluorine industry has developed for over 70 years. Concentrations of ∑PFAS were 210~3000 ng/L. Hexafluoropropylene oxide trimer acid (HFPO-TA) (mean 400 ng/L) was the dominant compound. Concentrations increased after running through fluorine-related factories. Near a historical fluorotelomer manufacturer, which was shut down in 2017, ∑PFAS concentration was still at a high-level of 1800 ng/L. Thirteen nontarget and suspect PFAS including 7 iodinated perfluoroalkyl acids (IPFAAs) were identified in 100% samples. N-methyl perfluoroalkyl sulfonamido acetic acids (MeFASAAs) could transform through oxidation, deacetylation, and hydroxylation reactions. A total of 8134 DOM molecular formulas were identified, with the highest proportion of CHOS (24%) and lignin (36%). Wastewater discharges and industrial runoff were the main sources. Microbial degradation and eutrophication could affect DOM composition. When assigning F element, F-containing compounds (55%) were the dominant, suggesting anthropogenic influences. The mean F/C values of DOM assigned compounds were 0.276, lower than nontarget screening compounds of 1.77. Emerging PFAS, i.e., perfluorobutanoic acid (PFBA) and perfluorobutanesulfonic acid (PFBS) were negatively related to DOM (p<0.05) due to competitive adsorption and microorganism activities. This study revealed persistent impact of fluorine related industries to environments, and provided a unique perspective on the environmental behavior of PFAS and DOM in aquatic environments.