User:Jhurley/sandbox - Revision history

Jhurley: /* Introduction to LEAF */

2026-08-13T22:39:47Z

‎Introduction to LEAF

Jhurley: /* Introduction to LEAF */

2026-08-13T21:36:48Z

‎Introduction to LEAF

Jhurley: /* Method Development for PFAS */

2026-08-13T21:33:50Z

‎Method Development for PFAS

Jhurley: /* Introduction to LEAF */

2026-08-13T21:29:45Z

‎Introduction to LEAF

Jhurley: /* Introduction to LEAF */

2026-08-13T21:29:22Z

‎Introduction to LEAF

Jhurley: /* Introduction to LEAF */

2026-08-13T21:27:49Z

‎Introduction to LEAF

Jhurley: /* Column Test Demonstration Studies */

2026-08-13T21:26:27Z

‎Column Test Demonstration Studies

Jhurley: /* Batch Test Demonstration Studies */

2026-08-13T21:24:35Z

‎Batch Test Demonstration Studies

Jhurley at 19:25, 13 August 2026

2026-08-13T19:25:22Z

Jhurley: /* See Also */

2026-08-13T19:24:24Z

‎See Also

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 ==Method Development for PFAS==

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 ==Introduction to LEAF==
-The [https://www.epa.gov/ U.S. Environmental Protection Agency (EPA)] [https://www.epa.gov/hw-sw846/leaching-environmental-assessment-framework-leaf-methods-and-guidance Leaching Environmental Assessment Framework (LEAF)] is a suite of standardized test methods for evaluating contaminant release from solids under environmentally relevant conditions (Table 1). The four leaching methods within LEAF were originally validated for inorganic constituents<ref>Garrabrants, A.C., Kosson, D.S., Stefanski, L., DeLapp, R., Seignette, P.F.A.B., van der Sloot, H.A., Kariher, P., Baldwin, M., 2012. Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1313 and Method 1316, EPA/600/R-12/623, U.S. Environmental Protection Agency, Air Pollution and Control Division. [[Media: EPA 600_R-12_623.pdf | Free Download EPA 600/R-12/623]]</ref><ref>Garrabrants, A.C., Kosson, D.S., DeLapp, R., Kariher, P., Seignette, P.F.A.B., van der Sloot, H.A., Stefanski, L., Baldwin, M., 2012. Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1314 and Method 1315, EPA/600/R-12/624, U.S. Environmental Protection Agency, Air Pollution and Control Division. [[Media: EPA 600_R-12_624.pdf | Free Download EPA 600/R-12/624]]</ref> and included as standard leaching methods EPA 1313 – 1316 within Update V of SW-846<ref>USEPA, 2026. Hazardous Waste Test Methods / SW-846. [https://www.epa.gov/hw-sw846 USEPA SW-846 website]</ref>. To address the need for standardized tests to evaluate PFAS leaching and mobility, LEAF methods have been optimized and demonstrated for use with PFAS (Methods 1313A-1316A)<ref name="GarrabrantsEtAl2024">Garrabrants, A.C., Liu, F., Warne, R., DeLapp, R., Brown, L., Rubin, Z., Yawson, D., Kosson, D.S., Guelfo, J.L., Real, M.I., van der Sloot, H.A., Touati, A., Thorneloe, S., 2024. Development of Leaching Tests for Materials Containing SVOCs and PFAS, EPA 600/R-23/382, USEPA, Washington, D.C. [[Media: EPA 600_R-23_382.pdf | Free Download EPA 600/R-23/382]]</ref>. This article will focus on Methods 1313A, 1314A, and 1316A. Demonstration of Method 1315A for compacted granular materials (including concrete and asphalt) is ongoing.
+The [https://www.epa.gov/ U.S. Environmental Protection Agency (EPA)] [https://www.epa.gov/hw-sw846/leaching-environmental-assessment-framework-leaf-methods-and-guidance Leaching Environmental Assessment Framework (LEAF)] is a suite of standardized test methods for evaluating contaminant release from solids under environmentally relevant conditions (Table 1). The four leaching methods within LEAF were originally validated for inorganic constituents<ref>Garrabrants, A.C., Kosson, D.S., Stefanski, L., DeLapp, R., Seignette, P.F.A.B., van der Sloot, H.A., Kariher, P., Baldwin, M., 2012. Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1313 and Method 1316, EPA/600/R-12/623, U.S. Environmental Protection Agency, Air Pollution and Control Division. [[Media: EPA 600_R-12_623.pdf | Free Download EPA 600/R-12/623]]</ref><ref>Garrabrants, A.C., Kosson, D.S., DeLapp, R., Kariher, P., Seignette, P.F.A.B., van der Sloot, H.A., Stefanski, L., Baldwin, M., 2012. Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1314 and Method 1315, EPA/600/R-12/624, U.S. Environmental Protection Agency, Air Pollution and Control Division. [[Media: EPA 600_R-12_624.pdf | Free Download EPA 600/R-12/624]]</ref> and included as standard leaching methods EPA 1313 – 1316 within Update V of SW-846<ref>USEPA, 2026. Hazardous Waste Test Methods / SW-846. [https://www.epa.gov/hw-sw846 USEPA SW-846 website]</ref>. To address the need for standardized tests to evaluate PFAS leaching and mobility, LEAF methods have been optimized and demonstrated for use with PFAS (Methods 1313A-1316A)<ref name="GarrabrantsEtAl2024">Garrabrants, A.C., Liu, F., Warne, R., DeLapp, R., Brown, L., Rubin, Z., Yawson, D., Kosson, D.S., Guelfo, J.L., Real, M.I., van der Sloot, H.A., Touati, A., Thorneloe, S., 2024. Development of Leaching Tests for Materials Containing SVOCs and PFAS, EPA 600/R-23/382, USEPA, Washington, D.C. [[Media: EPA 600_R-23_382.PDF | Free Download EPA 600/R-23/382]]</ref>. This article will focus on Methods 1313A, 1314A, and 1316A. Demonstration of Method 1315A for compacted granular materials (including concrete and asphalt) is ongoing.
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 ==Method Development for PFAS==
-Complete details of the development of LEAF Methods 1313A, 1314A, and 1316A for use with PFAS are available in Garrabrants ''et al.'', 2025<ref name="GarrabrantsEtAl2024"/>. Representative method modifications include:
+Complete details of the development of LEAF Methods 1313A, 1314A, and 1316A for use with PFAS are available in Garrabrants ''et al.'', 2024<ref name="GarrabrantsEtAl2024"/>. Representative method modifications include:
 * Materials of construction for experimental apparatus: containers used for leaching vessels (Methods 1313A, 1316A) and column construction materials (Method 1314A) evaluated for background PFAS and PFAS uptake.
 * Reagents and eluant composition: eluant composition was optimized to use 1 mM CaCl2 to reduce formation of colloidal matter; Method 1313A pH adjustment now conducted with nonoxidizing HCl.

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 ==Method Development for PFAS==

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 ==Method Development for PFAS==

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 ==Column Test Demonstration Studies==
 PFAS-specific adaptations were tested in column test demonstration studies, which included triplicate implementation of Method 1314A in three AFFF-impacted site soils.
 '''Draft Method 1314A''' was implemented in saturated, up-flow columns to evaluate leaching of PFAS as a function of cumulative L/S (∑(L/S)); Figure 3; total volume of water that has passed through the column divided by the soil mass in the column). As noted, the intent of Method 1314a and 1316a is similar, and in both tests, similar qualitative results were observed. For example, short-chain PFAS exhibited high initial concentrations that decreased rapidly. However, in Method 1314a, these rapid drops in short-chain PFAS tended to occur by ∑(L/S) ≈  2 (e.g., Site 1 and 3 soils, Figure 3) whereas in some cases, such as for PFHxS, Method 1316A produced slightly flatter elution curves than Method 1314A (Figures 2b and 3b). Long-chain PFAS generally displayed flatter elution profiles than short-chain PFAS across both methods. These trends are consistent with chain length dependent sorption documented in the literature<ref name="HigginsLuthy2006"/><ref name="NguyenEtAl2020"/><ref>Guelfo, J.L., Higgins, C.P., 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology, 47(9), pp. 4164–4171. [https://doi.org/10.1021/es3048043 doi: 10.1021/es3048043]</ref>. Although column modeling is beyond the scope of this article, prior studies have shown that saturated transport can be influenced by rate-limited desorption, particularly for long-chain PFAS<ref>Doria-Manzur, A., Gray, E.P., Streets, S.S., Guelfo, J.L., 2025. Per- and Polyfluoroalkyl Substances (PFAS) Transport from Biosolids-Amended Soils: An Experimental and Numerical Approach. Water Research, 288(Part B), Article 124674. [https://doi.org/10.1016/j.watres.2025.124674 doi: 10.1016/j.watres.2025.124674]&nbsp; [[Media: Doria-ManzurEtAl2026.pdf | Open Access Article]]</ref><ref>Guelfo, J.L., Wunsch, A., McCray, J., Stults, J.F., Higgins, C.P., 2020. Subsurface Transport Potential of Perfluoroalkyl Acids (PFAAs): Column Experiments and Modeling. Journal of Contaminant Hydrology, 233, Article 103661. [https://doi.org/10.1016/j.jconhyd.2020.103661 doi: 10.1016/j.jconhyd.2020.103661]&nbsp; [[Media: GuelfoEtAl2020.pdf | Open Access Manuscript]]</ref>. As noted, data from Methods 1316A and 1314A can support estimation of transport parameters representing equilibrium and nonequilibrium behavior, respectively.

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 PFAS-specific adaptations were tested in batch test demonstration studies, which included triplicate implementation of Methods 1313A and 1316A in four AFFF-impacted site soils.
 '''Draft Method 1313A''' was used to evaluate pH-dependent leaching in PFAS-contaminated soils in parallel batch extractions where each set of batch reactors is prepared and equilibrated at different pH (Figure 1).  Short-chain PFAS (≤6 fluorinated carbons) generally showed little to no variation in leaching across the tested pH range of 2-13 (e.g., [[Wikipedia: Perfluorohexanesulfonic acid | PFHxS]], Figure 1), whereas long-chain PFAS exhibited increased leaching at higher pH<ref name="GarrabrantsEtAl2024"/>. This trend is consistent with previous findings showing that soil-water partitioning coefficients (''K<sub>d</sub>'') decrease as pH increases (e.g., Higgins and Luthy 2006)<ref name="HigginsLuthy2006">Higgins, C.P., Luthy, R.G., 2006. Sorption of Perfluorinated Surfactants on Sediments. Environmental Science and Technology, 40(23), pp. 7251–7256. [https://doi.org/10.1021/es061000n doi: 10.1021/es061000n]</ref>. The most pronounced pH effects were observed for perfluoroalkyl sulfonamides (FASAs) such as [[Wikipedia: Perfluorooctanesulfonamide | perfluorooctane sulfonamide (FOSA)]], which transition from neutral to anionic forms within the circumneutral pH range (~pH 6). The anionic form has a lower ''K<sub>d</sub>'' and results in higher leaching concentrations<ref name="GarrabrantsEtAl2024"/><ref name="NguyenEtAl2020">Nguyen, T.M.H., Bräunig, J., Thompson, K., Thompson, J., Kabiri, S., Navarro, D.A., Kookana, R.S., Grimison, C., Barnes, C.M., Higgins, C.P., McLaughlin, M.J., Mueller, J.F., 2020. Influences of Chemical Properties, Soil Properties, and Solution pH on Soil–Water Partitioning Coefficients of Per- and Polyfluoroalkyl Substances (PFASs). Environmental Science and Technology, 54(24), pp. 15883–15892. [https://doi.org/10.1021/acs.est.0c05705 doi: 10.1021/acs.est.0c05705]&nbsp; [[Media: NguyenEtAl2020.pdf | Open Access Article]]</ref>. For many site management scenarios where pH is circumneutral, variations in anionic PFAS leaching are expected to be small over the relevant pH range. In such cases, when testing time and costs are primary considerations, Method 1313A may be a lower priority relative to evaluating leaching as a function of L/S (Method 1316A, Method 1314A).  Different considerations may be needed where FASAs or PFAS with multiple, ionizable functional groups (i.e., [[Wikipedia: Zwitterion | zwitterions]]) are of concern.
 '''Draft Method 1316A''' was used to evaluate L/S-dependent leaching of PFAS in impacted soils using parallel batch extractions where each set of batch reactors is prepared and equilibrated at a different L/S. (Figure 2).  Methods 1314A and 1316A are similar in intent as they both evaluate leaching as a function of L/S; however, the experimental approach differs.  Method 1314A uses a flow-through column configuration (Figure 3; discussed further below).  Method 1314A may better simulate field conditions, but Method 1316A is simpler and less costly to implement.  Trends in Method 1314A and 1316A are expected to be qualitatively similar but leaching concentrations are expected to exhibit differences. Despite this, leaching studies comparing Methods 1314A and 1316A for inorganics showed that cumulative release results were within one order of magnitude<ref>Lopez Meza, S., Garrabrants, A.C., van der Sloot, H., Kosson, D.S., 2008. Comparison of the Release of Constituents from Granular Materials under Batch and Column Testing. Waste Management, 28(10), pp. 1853–1867. [https://doi.org/10.1016/j.wasman.2007.11.009 doi: 10.1016/j.wasman.2007.11.009]</ref>.
 Method 1316A and Method 1314A may also provide different insights into transport mechanisms. Because Method 1316A is performed using equilibrated batch reactors at varying L/S, results can be used to develop equilibrium desorption isotherms and calculate desorption coefficients (e.g., ''K<sub><small>d,desorption</small></sub>''). Studies have shown that ''K<sub><small>d,desorption</small></sub>'' values for PFAS may be greater than ''K<sub><small>d</small></sub>'', an effect often attributed to desorption hysteresis<ref>Schaefer, C.E., Nguyen, D., Christie, E., Shea, S., Higgins, C.P., Field, J., 2022. Desorption Isotherms for Poly- and Perfluoroalkyl Substances in Soil Collected from an Aqueous Film-Forming Foam Source Area. Journal of Environmental Engineering, 148(1), Article 04021074. [https://doi.org/10.1061/(ASCE)EE.1943-7870.0001952 doi: 10.1061/(ASCE)EE.1943-7870.0001952]</ref>. Consequently Method 1316A provides a straightforward method to estimate site-specific desorption parameters. Although sorption parameters can also be inferred from column (Method 1314A) data, interpretation is often complicated by nonequilibrium processes.  Conversely, the column data can be valuable for quantifying those additional mechanisms providing transport parameters that can describe rate-limited transport (e.g., fraction of non-equilibrium sorption sites and sorption rates) and other dynamic behavior.

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 *[https://www.epa.gov/hw-sw846/how-guide-leaching-environmental-assessment-framework LEAF “How-To” Guide] - guidance on LEAF background, implementation, test result interpretation; includes case studies
 *[https://www.epa.gov/hw-sw846/leaching-environmental-assessment-framework-leaf-methods-and-guidance USEPA LEAF Methods and Guidance] homepage
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← Older revision		Revision as of 19:24, 13 August 2026
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	==See Also==		==See Also==
−	*[https://serdp-estcp.mil/projects/details/a7e3f7b5-ed82-4591-adaa-6196ff33dd60 ESTCP Project ER20-5031 – In Situ Verification and Quantification of Naturally Occurring Dechlorination Rates in Clays: Demonstrating Processes that Mitigate Back-Diffusion and Plume Persistence]