PFAS immobilization with soil amendments - How immobilized is immobilized?

Area of Science:

• Environmental Chemistry
• Environmental Science
• Toxicology

Background:

• Perfluorooctane sulfonic acid (PFOS) is a persistent environmental contaminant found in firefighting foams (AFFF).
• PFOS contamination in soil poses risks due to its potential bioaccessibility and bioavailability.
• Understanding PFOS behavior in soil is critical for effective remediation.

Purpose of the Study:

• To evaluate the efficacy of RemBind®300 in immobilizing PFOS in AFFF-impacted soil.
• To assess the impact of RemBind®300 on PFOS bioaccessibility and bioavailability using in vitro and in vivo methods.
• To compare RemBind®300 immobilization efficacy with other remediation assays.

Main Methods:

• In vitro bioaccessibility assay (SBRC-I) and in vivo Sprague-Dawley rat bioassay were employed.
• Soil samples were treated with RemBind®300 (5% w/w) to assess PFOS immobilization.
• Physicochemical properties of soil (TOC, Al, Fe) were analyzed for correlation with PFOS desorption.

Main Results:

• RemBind®300 significantly reduced PFOS bioaccessibility (5.6% mean) and relative bioavailability (13.0% mean) compared to unamended soil (63.6% and 83.3% mean, respectively).
• Reduced PFOS desorption was attributed to enhanced hydrophobic and electrostatic interactions induced by RemBind®300.
• Immobilization efficacy calculated via bioaccessibility and bioavailability assays was lower than leaching and earthworm assays due to assay-specific factors.

Conclusions:

• RemBind®300 is effective in immobilizing PFOS in contaminated soil, significantly reducing its potential for uptake.
• Bioaccessibility and bioavailability assays provide valuable insights into PFOS immobilization efficacy, though assay complexity influences results.
• Further research is needed to optimize RemBind®300 application and understand its long-term performance in diverse soil matrices.