PFAS concentrations in soils: Background levels versus contaminated sites

Area of Science:

• Environmental Chemistry
• Soil Science
• Contaminant Hydrology

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Their widespread distribution and potential human health impacts raise significant concerns.
• Understanding PFAS behavior in soil is crucial for environmental risk assessment.

Purpose of the Study:

• To compile and analyze global soil concentration data for PFAS.
• To assess PFAS distribution across different site types and geographical regions.
• To evaluate the role of soil as a reservoir and potential transport medium for PFAS.

Main Methods:

• Literature review of published PFAS soil concentrations.
• Inclusion of data from a large curated database of PFAS soil concentrations at contaminated sites.
• Aggregation of data from over 30,000 samples across more than 2,500 global sites.

Main Results:

• PFAS were detected in soils at nearly all tested sites worldwide.
• Concentrations at contaminated sites were orders of magnitude higher than background levels, especially for PFOS.
• Significant PFAS retention in the vadose zone and leaching to groundwater were observed over decadal timeframes.

Conclusions:

• Soil serves as a significant global reservoir for PFAS.
• PFAS demonstrate long-term persistence and migration potential from soil to water.
• Further research on PFAS transport and fate in soil and the vadose zone is critical.