The role of surface charge and pH changes in tropical soils on sorption behaviour of per- and polyfluoroalkyl substances (PFASs)

Oliver, Danielle P., Li, Yasong, Orr, Ryan, Nelson, Paul, Barnes, Mary, McLaughlin, Michael J., and Kookana, Rai S. (2019) The role of surface charge and pH changes in tropical soils on sorption behaviour of per- and polyfluoroalkyl substances (PFASs). Science of the Total Environment, 673. pp. 197-206.

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Abstract

This study investigated the effect of surface charge on the sorption of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) onto 7 tropical soils as a function of pH. The net surface charge became less negative with decreasing pH (from 7.5 to 3.5) in all soils. The rate of change in net surface charge varied from −0.6 to −2.8 (cmol/kg)/pH unit. The effect on sorption behaviour of PFASs was variable among soils. For two soils, the average sorption increased 54- and 45-fold for PFOS, 33- and 9-fold for PFOA, and 39- and 400-fold for PFHxS, across the pH range 7.5 to 3.5. Sorption in another sandier soil showed negligible change with decreasing pH. Sorption in the other soils did not change significantly until the pH decreased to approximately 5.5. The soils with high contents of sesquioxides (Fe and Al oxides) showed themostmarked increase in sorption with decreasing pH. This study demonstrated that in addition to hydrophobic interactionswith OC and other processes, electrostatic interactions are also important in the sorption process for these chemicals in soils. In acidic, variably charged tropical soils there is the possibility that any PFOS, PFOA or PFHxS sorbed to the soils may become desorbed if management practices (e.g. liming) raised soil pH.

Item ID: 52637
Item Type: Article (Research - C1)
ISSN: 1879-1026
Keywords: PFOS; PFOA; contamination; soil chemistry
Copyright Information: Crown Copyright © 2019 Published by Elsevier B.V. All rights reserved.
Funders: China Scholarship Council (CRC), NSW Environmental Trust
Date Deposited: 22 Aug 2019 06:31
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050304 Soil Chemistry (excl Carbon Sequestration Science) @ 70%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050207 Environmental Rehabilitation (excl Bioremediation) @ 30%
SEO Codes: 96 ENVIRONMENT > 9614 Soils > 961407 Urban and Industrial Soils @ 40%
96 ENVIRONMENT > 9609 Land and Water Management > 960911 Urban and Industrial Land Management @ 30%
96 ENVIRONMENT > 9612 Rehabilitation of Degraded Environments > 961208 Rehabilitation of Degraded Urban and Industrial Environments @ 30%
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