Sorbent assisted immobilisation of perfluoroalkyl acids in soils - effect on leaching and bioavailability

PFOA, PFOS and PFHxS toxicokinetic considerations for the development of an in vivo approach for assessing PFAS relative bioavailability in soil

A Sprague-Dawley rat model was utilized to elucidate perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) toxicokinetics with a goal of developing an in vivo approach for quantifying PFAS relative bioavailability in impacted soil. Following single dose administration (gavage) of ∼ 0.2-2000 µg kg-1 BW of PFOA, PFOS or PFHxS, differences in PFAS blood, organ and excreta concentrations were observed over 120 h although linear dose responses were determined for area under the blood plasma time curves (AUC; PFOA, PFHxS), liver accumulation (LA: PFOS) and urinary excretion (UE; PFOA, PFHxS). Oral and intravenous dose (∼20 µg kg-1 body weight) comparisons highlighted the high absolute bioavailability of PFOA (AUC: 100.3 ± 23.4 %; UE: 94.7 ± 26.6 %), PFOS (LA: 102.9 ± 15.6 %) and PFHxS (AUC: 88.3 ± 15.1 %; UE: 90.9 ± 7.3 %). Two spiked (14C-PFOA: 4360 ± 218 µg kg-1) and two PFAS impacted soils (PFOS: 1880-2250 µg kg-1; PFHxS: 61.2-65.5 µg kg-1) were utilized to measure PFAS relative bioavailability in soil matrices. In all soils, PFAS relative bioavailability was > 86 % (PFOA: 87.0-90.9 %; PFOS: 86.1-90.4 %; PFHxS: 86.5-97.0 %) although the method could quantify bioavailability reductions (25.6-88.9 %) when hydrophobic and electrostatic interactions were enhanced through the addition of carbon-based amendments (5-10 % w/w).

Migration and availability of Ni and Cd in industrial soils under different leaching conditions: Insights from DGT and DIFS models

Rainfall runoff can mobilize heavy metals in industrial soils, posing environmental risks. The mobility and distribution of heavy metals in different industrial soil layers are often overlooked. This study employed dynamic leaching experiments in layered soil columns with DGT (the diffusive gradients in thin films) measurements and DIFS (DGT-induced fluxes in soils and sediments) model to describe the migration, availability, and resupply ability of metals at different depths in surface and deep soil columns of industrial soils. Results showed significantly higher available concentrations (CDGT and CSoln) of Ni and Cd in surface soils compared to deep soils, likely due to the differences in soil physiochemical properties (contamination, pH, and soil texture). Continuous leaching promoted the migration of available Ni and Cd in surface soils. Maximum values of RNi (0.79-0.91) and RCd (0.75-0.80) were observed in the top layer (0-4 cm) of the surface soil, consistent with the trends of RFe. Combined DGT and DIFS model analysis implied higher potential availability and resupply of Ni and Cd in surface soil columns. These findings highlight the importance of considering dynamic leaching effects on heavy metal transport, availability, and release in industrial soils.

Green modification of biochar with poly(aspartic acid) enhances the remediation of Cd and Pb in water and soil

Biochar is a promising adsorbent for the remediation of heavy metals in water and soil. However, pristine biochar has a limited adsorption capacity for heavy metals, which restricts its application in the field of heavy metal immobilization. In the present study, the acidic amino acid-modified biochar was prepared, and its adsorption properties for cadmium (Cd) and lead (Pb) in aqueous solution were investigated. The results showed that poly(aspartic acid)-modified biochar (PASP-BC) was more effective in removing Cd(II) from water compared to biochar modified with poly(glutamic acid) (PGA-BC), aspartic acid (ASP-BC), and glutamic acid (GA-BC). The calculated maximum adsorption capacities, derived from Langmuir fitting parameters, for Cd(II) and Pb(II) by PASP-BC were 44.2 mg/g and 126.1 mg/g, respectively, which were 3.78 and 2.70 times higher than that for pristine BC. Based on the results from Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses, ion exchange, complexation, and electrostatic adsorption were identified as the mechanisms for Cd(II) and Pb(II) adsorption by PASP-BC. The results of the Toxicity Characteristic Leaching Procedure (TCLP) showed that PASP-BC effectively reduced the leachability of Cd and Pb by 91.2% and 84.7%, respectively, at a dosage of 3%. The pot experiment demonstrated that PASP-BC significantly reduced the bioavailability of heavy metals in Triticum aestivum L The maximum reduction in Cd and Pb content in roots was 76.3% and 72.6% when 3% PASP-BC was applied. Importantly, the application of PASP-BC decreased the translocation factor of heavy metals in wheat. Therefore, the green modification of biochar with poly(aspartic acid) has great potential in the heavy metals removal from wastewater and remediation in contaminated soil.

Soil amendments reduce PFAS bioaccumulation in Eisenia fetida following exposure to AFFF-impacted soil

The efficacy of RemBind® 300 to immobilize per- and polyfluoroalkyl substances (PFAS) in aqueous film forming foam (AFFF)-impacted soil (∑28 PFAS 1280-8130 ng g-1; n = 8) was assessed using leachability (ASLP) and bioaccumulation (Eisenia fetida) endpoints as the measure of efficacy. In unamended soil, ∑28 PFAS leachability ranged from 26.0 to 235 μg l-1, however, following the addition of 5% w/w RemBind® 300, ∑28 PFAS leachability was reduced by > 99%. Following exposure of E. fetida to unamended soil, ∑28 PFAS bioaccumulation ranged from 18,660-241,910 ng g-1 DW with PFOS accumulating to the greatest extent (15,150-212,120 ng g-1 DW). Biota soil accumulation factors (BSAF) were significantly (p < 0.05) higher for perfluoroalkyl sulfonic acids (PFSA; 13.2-50.9) compared to perfluoroalkyl carboxylic acids (PFCA; 1.2-12.7) while for individual PFSA, mean BSAF increased for C4 to C6 compounds (PFBS: 42.6; PFPeS: 52.7; PFHxS: 62.4). In contrast, when E. fetida were exposed to soil amended with 5% w/w RemBind® 300, significantly lower PFAS bioaccumulation occurred (∑28 PFAS: 339-3397 ng g-1 DW) with PFOS accumulation 23-246 fold lower compared to unamended soil. These results highlight the potential of soil amendments for reducing PFAS mobility and bioavailability, offering an immobilization-based risk management approach for AFFF-impacted soil.

Aminated clay-polymer composite as soil amendment for stabilizing the short- and long-chain per- and poly-fluoroalkyl substances in contaminated soil

Soils contaminated with per- and poly- fluoroalkyl substances (PFAS) require immediate remediation to protect the surrounding environment and human health. A novel animated clay-polymer composite was developed by applying polyethyleneimine (PEI) solution onto a montmorillonite clay-chitosan polymer composite. The resulting product, PEI-modified montmorillonite chitosan beads (MMTCBs) were characterized as an adsorptive soil amendment for immobilizing PFAS contaminants. The MMTCBs exhibited good efficiency to adsorb the PFAS, showing adsorption capacities of 12.2, 16.7, 18.5, and 20.8 mg g-1 for PFBA, PFBS, PFOA, and PFOS, respectively, which were higher than those obtained by granular activated carbon (GAC) (i.e., an adsorbent used as a reference). Column leaching tests demonstrated that amending soil with 10% MMTCBs resulted in a substantial decrease in the leaching of PFOA, PFOS, PFBA, and PFBS by 90%, 100%, 64%, and 68%, respectively. These reductions were comparable to the values obtained for GAC-modified soil, particularly for long-chain PFAS. Incorporating MMTCBs into the soil not only preserved the structural integrity of the soil matrix but also enhanced its shear strength (kPa). Conversely, adding GAC to the soil resulted in a reduction of the soil's mechanical properties.

PFAS remediation in soil: An evaluation of carbon-based materials for contaminant sequestration

The presence of per- and poly-fluoroalkyl substances (PFAS) in soils is a global concern as these emerging contaminants are highly resistant to degradation and cause adverse effects on human and environmental health at very low concentrations. Sequestering PFAS in soils using carbon-based materials is a low-cost and effective strategy to minimize pollutant bioavailability and exposure, and may offer potential long-term remediation of PFAS in the environment. This paper provides a comprehensive evaluation of current insights on sequestration of PFAS in soil using carbon-based sorbents. Hydrophobic effects originating from fluorinated carbon (C-F) backbone "tail" and electrostatic interactions deriving from functional groups on the molecules' "head" are the two driving forces governing PFAS sorption. Consequently, varying C-F chain lengths and polar functional groups significantly alter PFAS availability and leachability. Furthermore, matrix parameters such as soil organic matter, inorganic minerals, and pH significantly impact PFAS sequestration by sorbent amendments. Materials such as activated carbon, biochar, carbon nanotubes, and their composites are the primary C-based materials used for PFAS adsorption. Importantly, modifying the carbon structural and surface chemistry is essential for increasing the active sorption sites and for strengthening interactions with PFAS. This review evaluates current literature, identifies knowledge gaps in current remediation technologies and addresses future strategies on the sequestration of PFAS in contaminated soil using sustainable novel C-based sorbents.

Assessing the impact of immobilisation on the bioavailability of PFAS to plants in contaminated Australian soils

Per- and polyfluoroalkyl substances (PFAS) have become a key concern to both environmental and human health due to their extreme persistence in the environment and their ability to bioaccumulate in plants, animals, and humans. In this mesocosm study, Australian PFAS-contaminated soil with a mean total concentration of 8.05 mg/kg and a mean combined PFHxS + PFOS concentration of 7.89 mg/kg was treated with an immobilisation sorbent (RemBind®) at different application rates (0.5, 1, 1.5, 2, 3, 4, and 5% w/w). To assess the efficacy of this immobilisation treatment, PFAS leachability, PFAS plant uptake, and ecotoxicity tests were conducted. Leachability testing was performed according to the Australian Standard Leaching Procedure (ASLP) at pH 5 and 7. A grass species (Dactylis glomerata) was used to measure plant uptake of PFAS from untreated and treated contaminated soil. In addition, the Microtox test was used to assess the associated ecotoxicity. The immobilisation treatment resulted in a significant reduction of 88.5-99.8% in the total PFAS leachability and 88.7-99.8% in the combined PFOS and PFHxS leachability at pH 5. Similarly, significant reductions (5-12-fold) were observed in the plant uptake of total PFAS and combined PFOS and PFHxS in all treated soil samples. In addition, although the Microtox test showed relatively low ecotoxicity in all the experimental samples, including the untreated soil, a significant decrease in the ecotoxicity of treated soil samples was observed. The results from this study highlight that this treatment approach has the potential to reduce both PFAS leachability and plant bioavailability with a relatively low associated ecotoxicity. This is likely to reduce the risk of the transfer of PFAS into higher trophic levels. This immobilisation treatment may, therefore, reduce the risk associated with PFAS-contaminated soils and may be an important remediation tool for managing certain PFAS-contaminated soils.

Immobilization of per- and polyfluoroalkyl substances (PFAS): Comparison of leaching behavior by three different leaching tests

The evaluation of PFAS immobilization performance in laboratory experiments, especially the long-term stability, is a challenge. To contribute to the development of adequate experimental procedures, the impact of experimental conditions on the leaching behavior was studied. Three experiments on different scales were compared: batch, saturated column, and variably saturated laboratory lysimeter experiments. The Infinite Sink (IS) test - a batch test with repeated sampling - was applied for PFAS for the first time. Soil from an agricultural field amended with paper-fiber biosolids polluted with various perfluoroalkyl acids (PFAAs; 655 μg/kg ∑¹⁸PFAAs) and polyfluorinated precursors (1.4 mg/kg ∑¹⁸precursors) was used as the primary material (N-1). Two types of PFAS immobilization agents were tested: treatment with activated carbon-based additives (soil mixtures: R-1 and R-2), and solidification with cement and bentonite (R-3). In all experiments, a chain-length dependent immobilization efficacy is observed. In R-3, the leaching of short-chain PFAAs was enhanced relative to N-1. In column and lysimeter experiments with R-1 and R-2, delayed breakthrough of short-chain PFAAs (C4) occurred (> 90 days; in column experiments at liquid-to-solid ratio (LS) > 30 L/kg) with similar temporal leaching rates suggesting that leaching in these cases was a kinetically controlled process. Observed differences between column and lysimeter experiments may be attributed to varying saturation conditions. In IS experiments, PFAS desorption from N-1, R-1, and R-2 is higher than in the column experiments (N-1: +44 %; R-1: +280 %; R-2: +162 %), desorption of short-chain PFAS occurred predominantly in the initial phase (< 14 days). Our findings demonstrate that sufficient operating times are essential in percolation experiments, e.g., in column experiments >100 days and LS > 30 L/kg. IS experiments may provide a faster estimate for nonpermanent immobilization. The comparison of experimental data from various experiments is beneficial to evaluate PFAS immobilization and to interpret leaching characteristics.

Stabilisation of PFAS in soils: Long-term effectiveness of carbon-based soil amendments

Immobilisation/stabilisation is one of the most developed and studied approaches for treating soils contaminated with per- and poly-fluoroalkyl substances (PFAS). However, its application has been inhibited by insufficient understanding of the effectiveness of added soil sorbents over time. Herein, we present results on the effectiveness of select carbon-based sorbents, over 4 years (longevity) and multiple laboratory leaching conditions (durability). Standard batch leaching tests simulating aggressive, worst-case scenario conditions for leaching (i.e., shaking for 24-48 h at high liquid/solid ratios) were employed to test longevity and durability of stabilisation in clay-loam and sandy-loam soils historically contaminated with PFAS (2 and 14 mg/kg ∑₂₈ PFAS). The different sorbents, which were applied at 1-6% (w/w), reduced leaching of PFAS from the soils to varying degrees. Among the 5 sorbents tested, initial assessments completed 1 week after treatment revealed that 2 powdered activated carbon (PAC) sorbents and 1 biochar were able to reduce leaching of PFAS in the soil by at least 95%. Four years after treatment, the performance of the PAC sorbents did not significantly change, whilst colloidal AC improved and was able to reduce leaching of PFAS by at least 94%. The AC-treated soils also appeared to be durable and achieved at least 95% reduction in PFAS leaching under repetitive leaching events (5 times extraction) and with minimal effect of pH (pH 4-10.5). In contrast, the biochars were affected by aging and were at least 22% less effective in reducing PFAS leaching across a range of leaching conditions. Sorbent performance was generally consistent with the sorbent's physical and chemical characteristics. Overall, the AC sorbents used in this study appeared to be better than the biochars in stabilising PFAS in the long term.

The efficacy of soil washing for the remediation of per- and poly-fluoroalkyl substances (PFASs) in the field

This paper aims to describe the performance of a soil washing plant (SWP) for remediating a per- and poly-fluoroalkyl substances (PFASs)-contaminated soil with a high clay content (61%). The SWP used both physical and chemical processes; fractionation of the soil particles by size and partitioning of PFASs into the aqueous phase to remove PFASs from the soil. Contaminated water was treated in series with granulated activated carbon (GAC) and ion-exchange resin and reused within the SWP. Approximately 2200 t (dry weight) of PFAS-contaminated soil was treated in 25 batches of 90 t each, with a throughput of approximately 11 t soil/hr. Efficiency of the SWP was measured by observed decreases in total and leachable concentrations of PFASs in the soil. Average removal efficiencies (RE) were up to 97.1% for perfluorocarboxylic acids and 94.9% for perfluorosulfonic acids. REs varied among different PFASs depending on their chemistry (functional head group, carbon chain length) and were independent of the total PFAS concentrations in each soil batch. Mass balance analysis found approximately 90% of the PFAS mass in the soil was transferred to the wash solution and > 99.9% of the PFAS mass in the wash solution was transferred onto the GAC without any breakthrough.

Changing bioavailability of per- and polyfluoroalkyl substances (PFAS) to plant in biosolids amended soil through stabilization or mobilization

Biosolids containing per- and polyfluoroalkyl substances (PFAS) could contaminate the receiving environments once they are land applied. In this study, we evaluated the feasibility of controlling the bioavailability of PFAS in biosolids to timothy-grass through stabilization or mobilization approaches. Stabilization was accomplished by adding a sorbent (i.e. granular activated carbon (GAC), RemBind, biochar) to biosolids, while mobilization was achieved by adding a surfactant, sodium dodecyl sulphate (SDS), to biosolids. The results showed that the ΣPFAS concentration in grass shoots grown in biosolids amended soil treated by GAC or RemBind at 2% was only 2.77% and 3.35% of the ΣPFAS concentration detected in shoots grown in biosolids amended soil without a sorbent, respectively, indicating the effectiveness of GAC and RemBind for stabilizing PFAS and reduce their bioavailability. On the other hand, mobilization by adding SDS to biosolids at a dose range of 10-100 mg/kg significantly increased the plant uptake of ΣPFAS by 15.48%-108.57%. Thus, mobilization by adding SDS could be a valuable approach for enhancing the PFAS removal if phytoremediation is applied. Moreover, higher rate of PFAS uptake took place after grass cutting was observed in this study. Thus, proper mowing and regrowth of timothy-grass could lead to efficient and cost-effective removal of PFAS from biosolids amended soil through phytoremediation and leave the site clean to be used for other purposes.

Application of soil amendments for reducing PFAS leachability and bioavailability

In this study, changes in PFAS leachability and bioavailability were determined following the application of RemBind®100 (R100) and RemBind®300 (R300; 1-10% w/w) to PFAS-contaminated soil (Ʃ₂₈ PFAS 3.093-32.78 mg kg^-1). Small differences were observed in PFAS immobilization efficacy when soil was amended with RemBind® products although adding 5% w/w of either product resulted in a >98% reduction in ASLP PFAS leachability. Variability in immobilization efficacy was attributed to differences in activated carbon composition which influenced physicochemical properties of RemBind® formulations and PFAS sorption. PFOS, PFHxS and PFOA relative bioavailability was also assessed in unamended and amended soil (5% w/w) using an in vivo mouse model. In unamended soil, PFAS relative bioavailability was >60% with differences attributed to physicochemical properties of soil which influenced electrostatic and hydrophobic interactions. However, when PFAS relative bioavailability was assessed in soil amended with 5% w/w R100, individual PFAS relative bioavailability was reduced to 16.1 ± 0.8% to 26.1 ± 0.9% with similar results observed when R300 (5% w/w) was utilised (14.4 ± 1.6% to 24.3 ± 0.8%). Results from this study highlight that soil amendments have the potential to reduce both PFAS leachability and relative bioavailability thereby decreasing mobility and potential exposure to soil-borne contaminants.

Montmorillonite clay-based sorbents decrease the bioavailability of per- and polyfluoroalkyl substances (PFAS) from soil and their translocation to plants

Consumption of food and water contaminated with per- and polyfluoroalkyl substances (PFAS) presents a significant risk for human exposure. There is limited data on high affinity sorbents that can be used to reduce the bioavailability of PFAS from soil and translocation to plants and garden produce. To address this need, montmorillonite clay was amended with the nutrients carnitine and choline to increase the hydrophobicity of the sorbent and the interlayer spacing. In this study, the binding of PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid) to parent and amended clays was characterized. Isothermal analyses were conducted at pH 7 and ambient temperature to simulate environmentally-relevant conditions. The data for all tested sorbents fit the Langmuir model indicating saturable binding sites with high capacities and affinities under neutral conditions. Amended montmorillonite clays had increased capacities for PFOA and PFOS (0.51-0.71 mol kg^-1) compared to the parent clay (0.37-0.49 mol kg^-1). Molecular dynamics (MD) simulations suggested that hydrophobic and electrostatic interactions at the terminal fluorinated carbon chains of PFAS compounds were major modes of surface interaction. The safety and efficacy of the clays were confirmed in a living organism (Lemna minor), where clays (at 0.1% inclusion) allowed for increased growth compared to PFOA and PFOS controls (p ≤ 0.01). Importantly, soil studies showed that 2% sorbent inclusion could significantly reduce PFAS bioavailability from soil (up to 74%). Studies in plants demonstrated that inclusion of 2% sorbent significantly reduced PFAS residues in cucumber plants (p ≤ 0.05). These results suggest that nutrient-amended clays could be included in soil to decrease PFAS bioavailability and translocation of PFAS to plants.

Reduced bioaccumulation of fluorotelomer sulfonates and perfluoroalkyl acids in earthworms (Eisenia fetida) from soils amended with modified clays

Soils contaminated by per- and polyfluoroalkyl substances (PFAS) pose long-term sources to adjacent water bodies and soil invertebrates. The study investigated the stabilization using a modified clay adsorbent (FLUORO-SORB100®) in reducing the bioaccumulation of 13 anionic PFAS by earthworms (Eisenia fetida), as compared to coal-based granular activated carbon. The target PFAS included four perfluoroalkyl sulfonates such as perfluorooctane sulfonate (PFOS), six perfluoroalkyl carboxylates (e.g., perfluorooctanoate PFOA), and three (X:2) fluorotelomer sulfonates. Laboratory-spiked surface soil and the soil collected from a site contaminated by aqueous film-forming foams were examined. Both adsorbents resulted in reduced earthworm PFAS body burdens at the end of the 28-day uptake phase. The highest adsorbent amendment concentration (4 w/w%) was most effective, achieving >95% reduction of PFAS body burden. Soil leaching tests indicated better immobilization performance by the clay adsorbent for most analytes; in comparison, the activated carbon performed better at reducing total PFAS body burdens, possibly owing to the avoidance of larger-sized particles by earthworms. Strong positive logarithm relationships were observed between leachate concentrations and earthworm body burdens for most PFAS in the spiked soil. The study demonstrated that stabilization of PFAS using modified clay adsorbents can achieve concurrent benefits of lowering leachability and reducing bioaccumulation.

Field-Scale Demonstration of PFAS Leachability Following In Situ Soil Stabilization

A field-scale validation is summarized comparing the efficacy of commercially available stabilization amendments with the objective of mitigating per- and polyfluoroalkyl substance (PFAS) leaching from aqueous film-forming foam (AFFF)-impacted source zones. The scope of this work included bench-scale testing to evaluate multiple amendments and application concentrations to mitigate PFAS leachability and the execution of field-scale soil mixing in an AFFF-impacted fire-training area with nearly 2.5 years of post-soil mixing monitoring to validate reductions in PFAS leachability. At the bench scale, several amendments were evaluated and the selection of two amendments for field-scale evaluation was informed: FLUORO-SORB Adsorbent (FS) and RemBind (RB). Five ∼28 m³ test pits (approximately 3 m wide by 3 m long by 3 m deep) were mixed at a site using conventional construction equipment. One control test pit (Test Pit 1) included Portland cement (PC) only (5% dry weight basis). The other four test pits (Test Pits 2 through 5) compared 5 and 10% ratios (dry weight basis) of FS and RB (also with PC). Five separate monitoring events included two to three sample cores collected from each test pit for United States Environmental Protection Agency (USEPA) Method 1315 leaching assessment. After 1 year, a mass balance for each test pit was attempted comparing the total PFAS soil mass before, during, and after leach testing. Bench-scale and field-scale data were in good agreement and demonstrated >99% decrease in total PFAS leachability (mass basis; >98% mole basis) as confirmed by the total oxidizable precursor assay, strongly supporting the chemical stabilization of PFAS.

Comparing the Leaching Behavior of Per- and Polyfluoroalkyl Substances from Contaminated Soils Using Static and Column Leaching Tests

Soil contaminated with aqueous film-forming foams (AFFFs) containing per- and polyfluoroalkyl substances (PFASs) at firefighting training sites has become a major concern worldwide. To date, most studies have focused on assessing soil-water partitioning behavior of PFASs and the key factors that can affect their sorption, whereas PFASs leaching from contaminated soils have not yet been widely investigated. This study evaluated the leaching and desorption of a wide range of PFASs from twelve contaminated soils using the Australian Standard Leaching Procedure (ASLP), the U.S. EPA Multiple Extraction Procedure (MEP), and Leaching Environmental Assessment Framework (LEAF). All three leaching tests provided a similar assessment of PFAS leaching behavior. Leaching of PFASs from soils was related to C-chain lengths and their functional head groups. While short-chain (CF₂ ≤ 6) PFASs were easily desorbed and leached, long-chain PFASs were more difficult to desorb. PFASs with a carboxylate head group were leached more readily and to a greater extent than those with a sulfonate or sulfonamide head group. Leaching of long-chain PFASs was pH-dependent where leaching increased at high pH, while leaching of short-chain PFASs was less sensitive to pH. Comparing different leaching tests showed that the results using the alkaline ASLP were similar to the cumulative MEP data and the former might be more practical for routine use than the MEP. No single soil property was adequately able to describe PFAS leaching from the soils. Overall, the PFAS chemical structure appeared to have a greater effect on PFAS leaching from soil than soil physicochemical properties.