A critical review of modeling Poly- and Perfluoroalkyl Substances (PFAS) in the soil-water environment

Matthew W Sima; Peter R Jaffé

doi:10.1016/j.scitotenv.2020.143793

A critical review of modeling Poly- and Perfluoroalkyl Substances (PFAS) in the soil-water environment

Sci Total Environ. 2021 Feb 25:757:143793. doi: 10.1016/j.scitotenv.2020.143793. Epub 2020 Nov 24.

Authors

Matthew W Sima¹, Peter R Jaffé²

Affiliations

¹ Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA.
² Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA. Electronic address: Jaffe@Princeton.edu.

PMID: 33303199
DOI: 10.1016/j.scitotenv.2020.143793

Abstract

Due to their health effects and the recalcitrant nature of their CF bonds, Poly- and Perfluoroalkyl Substances (PFAS) are widely investigated for their distribution, remediation, and toxicology in ecosystems. However, very few studies have focused on modeling PFAS in the soil-water environment. In this review, we summarized the recent development in PFAS modeling for various chemical, physical, and biological processes, including sorption, volatilization, degradation, bioaccumulation, and transport. PFAS sorption is kinetic in nature with sorption equilibrium commonly quantified by either a linear, the Freundlich, or the Langmuir isotherms. Volatilization of PFAS depends on carbon chain length and ionization status and has been simulated by a two-layer diffusion process across the air water interface. First-order kinetics is commonly used for physical, chemical, and biological degradation processes. Uptake by plants and other biota can be passive and/or active. As surfactants, PFAS have a tendency to be sorbed or concentrated on air-water or non-aqueous phase liquid (NAPL)-water interfaces, where the same three isotherms for soil sorption are adopted. PFAS transport in the soil-water environment is simulated by solving the convection-dispersion equation (CDE) that is coupled to PFAS sorption, phase transfer, as well as physical, chemical, and biological transformations. As the physicochemical properties and concentration vary greatly among the potentially thousands of PFAS species in the environment, systematic efforts are needed to identify models and model parameters to simulate their fate, transport, and response to remediation techniques. Since many process formulations are empirical in nature, mechanistic approaches are needed to further the understanding of PFAS-soil-water-plant interactions so that the model parameters are less site dependent and more predictive in simulating PFAS remediation efficiency.

Keywords: Interface; PFAS; Plants; Soil; Sorption; Transport.

Publication types

Review