Differential Sorption of Short-Chain versus Long-Chain Anionic Per- and Poly-Fluoroalkyl Substances by Soils

Research output: Contribution to journalArticlepeer-review

Abstract

The impact of chain length on the sorption of anionic PFAS by soils and sediments was investigated by aggregating and synthesizing data sets from the literature. Quantitative structure/property relationship (QSPR) analysis was applied to characterize the influence of molecular size and soil properties on sorption. The log of the organic carbon-normalized equilibrium sorption coefficient (Koc) exhibited a biphasic relationship with molar volume, wherein the log Koc values for the short-chain PFAS were generally greater than would be predicted using the QSPR correlation determined for the long-chain PFAS. This enhanced differential sorption is observed to different degrees for all studies, which are compiled and synthesized for the first time. The results reveal remarkable congruency across a wide array of soils comprising a large range of properties and indicate that the observed enhanced differential sorption of short-chain PFAS is a prevalent phenomenon. Aggregating the long-chain PFAS data for all soils and sediments with organic carbon contents > 1% produced a strong correlation, indicating that the resultant QSPR model can produce representative log Koc values irrespective of the other properties of the medium. Silt+clay content was shown to be an important soil component for the short-chain PFAS for most soils, as well as the long-chain PFAS for soils with organic carbon contents < 1%. The results indicate that while the simple Koc-foc approach may produce reasonable estimates of Kd values for long-chain anionic PFAS, particularly for soils and sediments with larger organic carbon contents, it is unlikely to do so for short-chain anionic PFAS.

Original languageEnglish (US)
Article number175
JournalEnvironments - MDPI
Volume10
Issue number10
DOIs
StatePublished - Oct 2023

Keywords

  • chain length
  • PFCAs
  • PFOA
  • PFOS
  • PFSAs
  • retention

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science

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