How is the process of PFAS retardation into soil and groundwater?
The process of PFAS (Per- and Polyfluoroalkyl Substances) retardation into soil and groundwater is complex, influenced by various factors including the chemical properties of PFAS, soil characteristics, and environmental conditions. PFAS are known for their persistence and mobility in the environment, making their retardation and remediation a significant challenge. Colloidal activated carbon (CAC) has been identified as a promising technique for the stabilization of PFAS in the subsurface, showing high retardation rates for long-chain PFAS and significantly higher retention rates compared to non-treated soils. This is attributed to the high partitioning coefficients (Kd values) of PFAS on CAC, indicating a strong sorption capacity. However, the effectiveness of CAC can be influenced by the presence of dissolved organic carbon (DOC), which can affect the sorption of PFAS, particularly for long-chain compounds. The fate and transport of PFAS in groundwater have been observed to be influenced by hydrophobic, air-water interfacial, and electrostatic partitioning processes, along with biotransformation and matrix diffusion. These processes can lead to the attenuation of PFAS concentrations along flow paths from source areas. Additionally, the environmental behavior of PFAS in the subsurface is controlled by hydrophobic and electrostatic interactions with soils, which are further affected by environmental factors such as solution pH, Ca2+ concentration, and natural organic matter content. Air-water interfacial adsorption has been highlighted as a significant retention mechanism in the vadose zone, potentially delaying PFAS from reaching groundwater for decades. This is consistent with findings that PFAS can be retained in lower-permeability soils, suggesting longer-term retention. Moreover, airborne PFAS emissions have been shown to contribute to soil and groundwater contamination, indicating that PFAS can be transported and deposited far from their original source areas. In summary, PFAS retardation in soil and groundwater is a multifaceted process, influenced by the chemical nature of PFAS, soil and groundwater interactions, and environmental dynamics. Understanding these processes is crucial for developing effective remediation strategies.
Answers from top 7 papers
| Papers (7) | Insight |
|---|---|
| Colloidal activated carbon (CAC) entrap PFAS in soil, reducing ∑11PFAS by 76% initially. However, rebound to 52% occurred due to plume bypass, emphasizing the need for detailed site understanding. | |
89 Citations | PFAS retardation in soil and groundwater is influenced by air-water interfacial adsorption, with significant retention in the vadose zone, leading to long transport times before reaching groundwater. |
| PFAS retardation into soil and groundwater occurs via airborne emissions and land deposition, leading to contamination in conserved forest lands beyond traditionally considered contamination zones. | |
28 Mar 2022 | PFAS retardation in soil and groundwater primarily occurs through sorption mechanisms involving hydrophobic interactions, electrostatic forces, hydrogen bonding, and functional group complexes, influenced by soil properties and solution chemistry. |
| Colloidal activated carbon (CAC) treatment significantly retards PFAS, especially long-chain ones, in soil, showing high retention rates and hindering transport in groundwater, with some elution observed. | |
28 Mar 2022 | Long-chain PFASs show higher retardation in soil and colloidal activated carbon, correlating with perfluorocarbon chain length. Short-chain PFASs exhibit faster breakthrough, especially in the presence of dissolved organic carbon. |
14 Citations | PFAS retardation into soil and groundwater occurs through hydrophobic, air-water interfacial, electrostatic partitioning, biotransformation, and matrix diffusion processes, varying based on site-specific conditions. |