In situ air-water and particle-water partitioning of perfluorocarboxylic acids, perfluorosulfonic acids and perfluorooctyl sulfonamide at a wastewater treatment plant

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In situ measurements of air and water phases at a wastewater treatment plant (WWTP) were used to investigate the partitioning behavior of perfluorocarboxylic acids (PFCAs), perfluorosulfonic acids (PFSAs) and perfluorooctyl sulfonamide (HFOSA) and their conjugate bases (PFC -s, PFS -s, and FOSA -, respectively). Particle-dissolved (R d) and air-water (Q AW) concentration ratios were determined at different tanks of a WWTP. Sum of concentrations of C 4-12, 14 PFC(A)s, C 4,6,8,10 PFS(A)s and (H)FOSA were as high as 50pgm -3 (atmospheric gas phase), 2300ngL -1 (aqueous dissolved phase) and 2500ngL -1 (aqueous particle phase). Particle-dissolved concentration ratios of total species, log R d, ranged from -2.9 to 1.3 for PFS(A)s, from -1.9 to 1.1 for PFC(A)s and was 0.71 for (H)FOSA. These field-based values agree well with equilibrium partitioning data reported in the literature, suggesting that any in situ generation from precursors, if they are present in this system, occurs at a slower rate than the rate of approach to equilibrium. Acid Q AW were also estimated. Good agreement between the Q AW and the air-water equilibrium partition coefficient for C 8PFCA suggests that the air above the WWTP tanks is at or near equilibrium with the water. Uncertainties in these Q AW values are attributed mainly to variability in pK a values reported in the literature. The WWTP provides a unique environment for investigating environmental fate processes of the PFCAs and PFSAs under 'real' conditions in order to better understand and predict their fate in the environment.

Original languageEnglish
Issue number8
Pages (from-to)941-948
Number of pages8
Publication statusPublished - 08.2013