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Behavior and Fate of PFOA and PFOS in Sandy Aquifer Sediment (journal)
Citation:
Ferrey, M. L., J. T. WILSON, C. J. ADAIR, C. SU, D. D. Fine, X. Liu, AND J. W. WASHINGTON. Behavior and Fate of PFOA and PFOS in Sandy Aquifer Sediment (journal). GROUNDWATER MONITORING AND REMEDIATION. National Ground Water Association, Westerville, OH, 32(4):63-71, (2012).
Impact/Purpose:
These observations suggest sorption of PFOA and PFOS was controlled by electrostatic sorption on ferric oxide minerals, and not by sorption to organic carbon.
Description:
Microcosms were constructed with sediment from beneath a landfill that received waste containing PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate). The microcosms were amended with PFOA and PFOS, and sampled after 91, 210, 343, 463, 574, and 740 days of incubation. After 740 days, selected microcosms were extracted to determine the mass of PFOA and PFOS remaining. There was no evidence for degradation of PFOA or PFOS. Over time, the aqueous concentrations of PFOA and PFOS increased in the microcosms, indicating that PFOA and PFOS that had originally sorbed to the sediment was desorbing. At the beginning of the experiment, the adsorption coefficient, Kd, averaged 0.27 L/kg for PFOA and 1.2 L/kg for PFOS. After 740 days of incubation, sorption of PFOA was not detectable and the Kd of PFOS was undetectable in two microcosms and was 0.08 L/kg in a third microcosm. During incubation, the pH of the pore water in the microcosms increased from pH 7.2 to pH ranging from 8.1 to 8.8 and the zeta potential of the sediment decreased with increasing pH. These observations suggest sorption of PFOA and PFOS was controlled by electrostatic sorption on ferric oxide minerals, and not by sorption to organic carbon.
