Per- and Poly-Fluoroalkyl Substances in Runoff and Leaching from AFFF-Contaminated Soils: a Rainfall Simulation Study

Area of Science:

• Environmental Science
• Environmental Chemistry
• Soil Science

Background:

• Per- and poly-fluoroalkyl substances (PFASs) are persistent environmental contaminants originating from aqueous film-forming foam (AFFF).
• Understanding PFAS mobilization via surface runoff and leaching from contaminated soils is critical for environmental risk assessment.
• The efficacy of remediation strategies, such as activated carbon (AC) application, in mitigating PFAS transport remains to be fully quantified.

Purpose of the Study:

• To evaluate PFAS losses in surface runoff and groundwater leachate from AFFF-contaminated soils under simulated rainfall conditions.
• To investigate the influence of soil properties, PFAS concentration, and AC treatment on PFAS mobilization.
• To assess the effectiveness of AC in reducing PFAS transport in runoff and leachate.

Main Methods:

• Laboratory-scale rainfall simulations were conducted on AFFF-contaminated soils with varying characteristics.
• PFAS concentrations in surface runoff and soil leachate were measured.
• The impact of activated carbon (AC) amendment on PFAS losses was evaluated.

Main Results:

• Leaching was the dominant loss pathway for lower PFAS concentrations (∑PFAS = 0.2-2 mg/kg), while runoff dominated at higher concentrations (∑PFAS = 31 mg/kg).
• Leachates consistently exhibited higher PFAS concentrations and diversity than runoff.
• PFAS losses were influenced by carbon chain length in leachate and initial soil concentration in runoff.
• Activated carbon (1% w/w) substantially reduced PFAS losses in both runoff and leachate, with sorption primarily occurring during rainfall events.

Conclusions:

• PFAS mobilization from contaminated soils is complex, influenced by soil properties and contaminant loading.
• Activated carbon shows significant potential for mitigating PFAS transport in both runoff and leachate.
• Further research is needed to optimize AC application for PFAS remediation in real-world scenarios.