Interaction between Per- and Polyfluoroalkyl Substances and Dissolved Organic Matter in Soil: Molecular Variation and...

Area of Science:

• Environmental Chemistry
• Soil Science
• Organic Geochemistry

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Their migration and fate in soil are influenced by soil properties, but the role of dissolved organic matter (DOM) is understudied.
• Understanding PFAS-DOM interactions is crucial for predicting contaminant transport.

Purpose of the Study:

• To investigate the interaction between PFAS and DOM in soil-porewater systems.
• To determine how DOM composition affects PFAS partitioning and distribution in field soil.
• To explore the relationship between PFAS burden and DOM characteristics.

Main Methods:

• Analysis of PFAS and DOM composition and distribution in field soil and soil-porewater.
• Quantification of total PFAS concentrations and characterization of DOM using techniques like Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS).
• Statistical analysis to correlate PFAS concentrations and partitioning with DOM properties and soil organic carbon content.

Main Results:

• Significant spatial variations in PFAS concentrations (3.14–50.92 ng/g) were observed.
• Higher PFAS burdens correlated with more labile and bioavailable DOM fractions (lipid/protein/amino-like) and higher DOM chemodiversity (Shannon index).
• Short-chain PFAS were particularly associated with these DOM changes. Protein-like DOM facilitated PFAS porewater partitioning, while humic-like DOM promoted soil adsorption.

Conclusions:

• DOM composition significantly dictates PFAS partitioning between soil and porewater, overriding correlations with soil organic carbon alone.
• Specific DOM components play contrasting roles: protein-like compounds enhance mobility, while humic-like compounds increase soil retention.
• These findings provide critical insights into the environmental fate and migration mechanisms of PFAS, particularly in relation to DOM dynamics.