Widespread use of perfluorooctane surfactants has led to ubiquitous presence of these chemicals in biological tissues. While perfluorooctane surfactants have been measured in blood and liver tissue samples of fish, birds, and mammals in the Great Lakes region, data for the aqueous concentrations of these compounds in the Great Lakes or other ambient waters is lacking. Sixteen Great Lakes water samples were analyzed for eight perfluorooctane surfactants. The monitored perfluorooctane surfactants were quantitatively determined using single quadrupole HPLC/MS and qualitatively confirmed using ion trap MS/MS. Additionally, PFOS was quantitatively confirmed using triple quadrupole LC/MS/MS. Concentrations of PFOS and PFOA in the two lakes ranged from 21-70 and 27-50 ng/L, respectively. Analysis also showed the presence of PFOS precursors, N-EtFOSAA (range of 4.2-11 ng/L) and FOSA (range of 0.6-1.3 ng/L), in all samples above the LOQ. PFOSulfinate, another precursor, was identified at six of eight locations with a concentration range, when present, of <2.2-17 ng/L. Other PFOS precursors, N-EtFOSE, PFOSAA, and N-EtFOSA were not observed at any of the sampling locations. These are the first reported concentrations of perfluorooctane surfactants in Great Lakes water and the first report of PFOS precursors in any water body.

The origin and amount of perfluorooctane surfactants in wastewater treatment systems, and the transformation these compounds may undergo during treatment, were evaluated through measurement and experiment. Influent, effluent, and river water at the point of discharge for a 6-MGD wastewater treatment plant (WWTP) were screened for eight perfluorooctane surfactants. N-EtFOSAA was quantified in influent (5.1 +/- 0.8 ng/L), effluent (3.6 +/- 0.2 ng/ L), and river water samples (1.2 +/- 0.3 ng/L), while PFOS and PFOA were quantified in effluent (26 +/- 2.0 and 22 +/- 2.1 ng/L, respectively) and river water (23 +/- 1.5 and 8.7 +/- 0.8 ng/L, respectively). Signals for PFOS and PFOA were observed in influent samples, but exact quantitative determination could not be made due to low recoveries of these two compounds in field spike samples. Although the source of PFOS and PFOA observed in WWTP effluents is not clear, two hypotheses were examined: (1) the highly substituted perfluorooctane surfactants that constitute commercially available fabric protectors can be transformed to PFOS and PFOA during biological treatment in wastewater treatment systems, and (2) the end products themselves are directly introduced to WWTPs because they are present as residual in the commercial mixtures. Biotransformation experiments of 96 h were run to determine whether N-EtFOSE (a primary monomer used in 3M's polymer surface protection products) could be transformed to lesser-substituted perfluorooctane compounds in bioreactors amended with aerobic and anaerobic sludge from the sampled plant. At the end of the aerobic biotransformation experiment, N-EtFOSAA and PFOSulfinate were the only two metabolites formed and each accounted for 23 +/- 5.0% and 5.3 +/- 0.8% of the transformed parent on a molar basis, respectively. Transformation of N-EtFOSE was not observed under anaerobic conditions. A sample of a commercially available surface protection product from 1994 was analyzed and found to contain six of the targeted perfluorinated surfactants, including PFOS and PFOA. These findings suggest transformation of precursors within wastewater treatment is not an important source of these compounds compared to direct use and disposal of products containing the end products as residual amounts.

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Perfluorooctane surfactants have been reported in biota, water, and air samples worldwide. Despite these reports, the main environmental sources of these compounds remain undefined. To address this gap in knowledge, an annual lakewide mass budget of eight perfluorooctane surfactants was developed for Lake Ontario. To determine the atmospheric contribution to the mass budget, over-the-lake gasphase air concentrations for N-EtFOSE and N-EtFOSA and particulate-phase air concentrations for PFOS in any air sample are reported for the first time, with mean concentrations when present of 0.5 ( 0.32 (N-EtFOSE gasphase), 1.1 ( 0.9 (N-EtFOSA gas-phase), and 6.4 ( 3.3 (PFOS particulate-phase) pg/m 3 . The mass budget finds inflow from Lake Erie (14 361 ( 4489 kg Σperfluorooctane surfactants) and wastewater discharge (1762 ( 2697 kg Σperfluorooctane surfactants) to be the major sources, while outflow through the St. Lawrence River is the dominant loss mechanism (22 727 ( 7060 kg/year Σperfluorooctane surfactants). Using the mass budget data, the steady state and measured mean concentrations in the lake water are the same at the 95% confidence level.