Oral Presentation Society of Environmental Toxicology and Chemistry Australasia 2021

Influences of Chemical Properties, Soil Properties, and Solution pH on Soil–Water Partitioning Coefficients of Per- and Polyfluoroalkyl Substances (PFASs) (#72)

Thi Minh Hong Nguyen 1 , Jennifer Bräunig 1 , Kristie Thompson 1 , Jack Thompson 1 , Shervin Kabiri 2 , Divina A. Navarro 3 , Charles Grimison 4 , Craig M. Barnes 5 , Christopher P. Higgins 1 6 , Michael J. McLaughlin 2 , Jochen Mueller 1
  1. Queensland Alliance for Environmental Health Sciences - QAEHS, The University of Queensland, Woolloongabba, QLD, Australia
  2. School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia, Australia
  3. CSIRO, The Commonwealth Scientific and Industrial Research Organisation, Land and Water, PMB 2, Glen Osmond, South Australia , Australia
  4. Ventia Pty Ltd., Chatswood, New South Wales, Australia
  5. Airservices Australia, 25 Constitution Avenue, Canberra, Australian Capital Territory , Australia
  6. Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado , United States

The aim of this study was to assess the soil–water partitioning behavior of a wider range of per- and polyfluoroalkyl substances (PFASs) onto soils covering diverse soil properties. The PFASs studied include perfluoroalkyl carboxylates (PFCAs), perfluoroalkane sulfonates (PFSAs), fluorotelomer sulfonates (FTSs), nonionic perfluoroalkane sulfonamides (FASAs), cyclic PFAS (PFEtCHxS), per- and polyfluoroalkyl ether acids (GenX, ADONA, 9Cl-PF3ONS), and three aqueous film-forming foam (AFFF)-related zwitterionic PFASs (AmPr-FHxSA, TAmPr-FHxSA, 6:2 FTSA-PrB). Soil–water partitioning coefficients (log Kd values) of the PFASs ranged from less than zero to approximately three, were chain-length-dependent, and were significantly linearly related to molecular weight (MW) for PFASs with MW > 350 g/mol (R2 = 0.94, p < 0.0001). Across all soils, the Kd values of all short-chain PFASs (≤5 −CF2– moieties) were similar and varied less (<0.5 log units) compared to long-chain PFASs (>0.5 to 1.5  log units) and zwitterions AmPr- and TAmPr-FHxSA (∼1.5 to 2 log units). Multiple soil properties described sorption of PFASs better than any single property. The effects of soil properties on sorption were different for anionic, nonionic, and zwitterionic PFASs. Solution pH could change both PFAS speciation and soil chemistry affecting surface complexation and electrostatic processes. The Kd values of all PFASs increased when solution pH decreased from approximately eight to three. Short-chain PFASs were less sensitive to solution pH than long-chain PFASs. The results indicate the complex interactions of PFASs with soil surfaces and the need to consider both PFAS type and soil properties to describe mobility in the environment.