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Bigler MC, Brusseau ML, Guo B, Jones SL, Pritchard JC, Higgins CP, Hatton J. High-Resolution Depth-Discrete Analysis of PFAS Distribution and Leaching for a Vadose-Zone Source at an AFFF-Impacted Site. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9863-9874. [PMID: 38780413 DOI: 10.1021/acs.est.4c01615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The long-term leaching of polyfluoroalkyl substances (PFAS) within the vadose zone of an AFFF application site for which the depth to groundwater is approximately 100 m was investigated by characterizing the vertical distribution of PFAS in a high spatial resolution. The great majority (99%) of PFAS mass resides in the upper 3 m of the vadose zone. The depths to which each PFAS migrated, quantified by moment analysis, is an inverse function of molar volume, demonstrating chromatographic separation. The PFAS were operationally categorized into three chain-length groups based on the three general patterns of retention observed. The longest-chain (>∼335 cm3/mol molar volume) PFAS remained within the uppermost section of the core, exhibiting minimal leaching. Conversely, the shortest-chain (<∼220 cm3/mol) PFAS accumulated at the bottom of the interval, which coincides with the onset of a calcic horizon. PFAS with intermediate-chain lengths were distributed along the length of the core, exhibiting differential magnitudes of leaching. The minimal or differential leaching observed for the longest- and intermediate-chain-length PFAS, respectively, demonstrates that retention processes significantly impacted migration. The accumulation of shorter-chain PFAS at the bottom of the core is hypothesized to result from limited deep infiltration and potential-enhanced retention associated with the calcic horizon.
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Affiliation(s)
- Matthew C Bigler
- Department of Environmental Science, The University of Arizona Tucson, Arizona 85721, United States
| | - Mark L Brusseau
- Department of Environmental Science, The University of Arizona Tucson, Arizona 85721, United States
- Hydrology and Atmospheric Sciences Department, The University of Arizona, Tucson, Arizona 85721, United States
| | - Bo Guo
- Hydrology and Atmospheric Sciences Department, The University of Arizona, Tucson, Arizona 85721, United States
| | - Sara L Jones
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - J Conrad Pritchard
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - James Hatton
- Jacobs Engineering Group, Greenwood Village, Colorado 80111, United States
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2
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Saha B, Ateia M, Fernando S, Xu J, DeSutter T, Iskander SM. PFAS occurrence and distribution in yard waste compost indicate potential volatile loss, downward migration, and transformation. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024; 26:657-666. [PMID: 38312055 DOI: 10.1039/d3em00538k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
We discovered high concentrations of PFAS (18.53 ± 1.5 μg kg-1) in yard waste compost, a compost type widely acceptable to the public. Seventeen out of forty targeted PFAS, belonging to six PFAS classes were detected in yard waste compost, with PFCAs (13.51 ± 0.99 μg kg-1) and PFSAs (4.13 ± 0.19 μg kg-1) being the dominant classes, comprising approximately 72.5% and 22.1% of the total measured PFAS. Both short-chain PFAS, such as PFBA, PFHxA, and PFBS, and long-chain PFAS, such as PFOA and PFOS, were prevalent in all the tested yard waste compost samples. We also discovered the co-occurrence of PFAS with low-density polyethylene (LDPE) and polyethylene terephthalate (PET) plastics. Total PFAS concentrations in LDPE and PET separated from incoming yard waste were 7.41 ± 0.41 μg kg-1 and 1.35 ± 0.1 μg kg-1, which increased to 8.66 ± 0.81 μg kg-1 in LDPE and 5.44 ± 0.56 μg kg-1 in PET separated from compost. An idle mature compost pile revealed a clear vertical distribution of PFAS, with the total PFAS concentrations at the surface level approximately 58.9-63.2% lower than the 2 ft level. This difference might be attributed to the volatile loss of short-chain PFCAs, PFAS's downward movement with moisture, and aerobic transformations of precursor PFAS at the surface.
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Affiliation(s)
- Biraj Saha
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, 1410 14th Ave N, CIE 201, Fargo, North Dakota 58102, USA.
| | - Mohamed Ateia
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
| | - Sujan Fernando
- Department of Civil and Environmental Engineering, Clarkson University, Potsdam, New York 13699, USA
| | - Jiale Xu
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, 1410 14th Ave N, CIE 201, Fargo, North Dakota 58102, USA.
| | - Thomas DeSutter
- Department of Soil Science, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Syeed Md Iskander
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, 1410 14th Ave N, CIE 201, Fargo, North Dakota 58102, USA.
- Environmental and Conservation Sciences, North Dakota State University, 1410 14th Ave N, CIE 201, Fargo, North Dakota 58108, USA
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Xu C, Xu C, Zhou Q, Shen C, Peng L, Liu S, Yin S, Li F. Spatial distribution, isomer signature and air-soil exchange of legacy and emerging poly- and perfluoroalkyl substances. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 343:123222. [PMID: 38145639 DOI: 10.1016/j.envpol.2023.123222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 12/27/2023]
Abstract
Widespread occurrences of various poly- and perfluoroalkyl substances (PFAS) in terrestrial environment calls for the growing interest in their transport behaviors. However, limited studies detected PFAS with structural diversity in tree barks, which reflect the long-term contamination in atmosphere and play a vital role in air-soil exchange behaviors. In this study, 26 PFAS congeners and typical branched isomers were investigated in surface soils and tree barks at 28 sites along the Taihu Lake, Taipu River, and Huangpu River. Concentrations of total PFAS in soils and tree barks were 0.991-29.4 and 7.99-188 ng/g dw, with PFPeA and PFDoA were the largest contributors in the two matrices. The highest PFAS levels were found in the Taihu Lake watershed, where textile manufacturing and metal plating activities highly prosper. With regard to the congener and isomer signatures, short-chain homologs dominated in soils (65.5%), whereas long-chain PFAS showed a major proportion in barks (41.9%). The composition of linear isomers of PFOS, PFOA and PFHxS implied that precursor degradation might be an important source of PFAS in addition to the 3M electrochemical fluorination (ECF). Additionally, the distance from the emission source, total organic carbon (TOC), logKOA and logKOW were considered potential influencing factors in PFAS distributions. Based on the multi-media fugacity model, about 71% of the fugacity fraction (ffs) values of the PFAS were below 0.3, indicating the dominant deposition from the atmosphere to the soil. The average fluxes of air-soil exchange for PFAS were -0.700 ± 11.0 ng/(m2·h). Notably, the estimated daily exposure to PFAS ranged from 9.57 × 10-2 to 8.59 × 10-1 ng/kg·bw/day for children and 3.31 × 10-2 to 3.09 × 10-1 ng/kg·bw/day for adults, suggesting low risks from outdoor inhalation and dermal uptake. Overall, results from distribution with structural diversity, air-soil exchange and preliminary risk assessment. This study provided in-depth insight of PFAS in multi-medium environment and bridged gaps between field data and policy-making for pollution control.
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Affiliation(s)
- Chenye Xu
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Chenman Xu
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China
| | - Quan Zhou
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China
| | - Chensi Shen
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China
| | - Leni Peng
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China
| | - Shuren Liu
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China
| | - Shanshan Yin
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China
| | - Fang Li
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China.
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Dai M, Yan N, Brusseau ML. Potential impact of bacteria on the transport of PFAS in porous media. WATER RESEARCH 2023; 243:120350. [PMID: 37499541 PMCID: PMC10530518 DOI: 10.1016/j.watres.2023.120350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 07/05/2023] [Accepted: 07/11/2023] [Indexed: 07/29/2023]
Abstract
The transport and fate of per- and poly-fluoroalkyl substances (PFAS) in soil and groundwater is a topic of critical concern. A number of factors and processes may influence the transport and fate of PFAS in porous media. One factor that has received minimal attention to date is the impact of bacteria on the retention and transport of PFAS, which is the focus of this current study. The first part of this work comprised a critical review of prior studies to delineate observed PFAS-bacteria interactions and to summarize the mechanisms of PFAS sorption and retention by bacteria. Retention of PFAS by bacteria can occur through sorption onto cell surfaces and/or by incorporation into the cell interior. Factors such as the molecular structure of PFAS, solution chemistry, and bacterial species can affect the magnitude of PFAS sorption. The influence of bacteria on the retention and transport of PFAS was investigated in the second part of the study with a series of batch and miscible-displacement experiments. Batch experiments were conducted using Gram-negative Pseudomonas aeruginosa and Gram-positive Bacillus subtilis to quantify the sorption of perfluorooctane sulfonic acid (PFOS). The results indicated that both bacteria showed strong adsorption of PFOS, with no significant difference in adsorption capacity. Miscible-displacement experiments were then conducted to examine the retention and transport of PFOS in both untreated sand and sand inoculated with Pseudomonas aeruginosa or Bacillus subtilis for 1 and 3 days. The transport of PFOS exhibited greater retardation for the experiments with inoculated sand. Furthermore, the enhanced sorption was greater for the 3-day inoculation compared to the 1-day, indicating that biomass is an important factor affecting PFOS transport. A mathematical model representing transport with nonlinear and rate-limited sorption successfully simulated the observed PFOS transport. This study highlights the need for future studies to evaluate the effect of bacteria on the transport of PFAS in soil and groundwater.
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Affiliation(s)
- Mengfan Dai
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China
| | - Ni Yan
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China.
| | - Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States; Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States.
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Brusseau ML. Determining air-water interfacial areas for the retention and transport of PFAS and other interfacially active solutes in unsaturated porous media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 884:163730. [PMID: 37120024 PMCID: PMC10330266 DOI: 10.1016/j.scitotenv.2023.163730] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/03/2023]
Abstract
The objective of this work was to determine the methods that produce the most representative measurements and estimations of air-water interfacial area specifically for the retention and transport of PFAS and other interfacially active solutes in unsaturated porous media. Published data sets of air-water interfacial areas obtained with multiple measurement and prediction methods were compared for paired sets of porous media comprising similar median grain diameters, but one with solid-surface roughness (sand) and one without roughness (glass beads). All interfacial areas produced with the multiple diverse methods were coincident for the glass beads, providing validation of the aqueous interfacial tracer-test methods. The results of this and other benchmarking analyses demonstrated that the differences in interfacial areas measured for sands and soil by different methods are not due to errors or artifacts in the methods but rather the result of method-dependent differential contributions of solid-surface roughness. The contributions of roughness to interfacial areas measured by interfacial tracer-test methods were quantified and shown to be consistent with prior theoretical and experiment-based investigations of air-water interface configurations on rough solid surfaces. Three new methods for estimating air-water interfacial areas were developed, one based on the scaling of thermodynamic-determined values and the other two comprising empirical correlations incorporating grain diameter or NBET solid surface area. All three were developed based on measured aqueous interfacial tracer-test data. The three new and three existing estimation methods was tested using independent data sets of PFAS retention and transport. The results showed that the method based on treating air-water interfaces as smooth surfaces as well as the standard thermodynamic method produced inaccurate air-water interfacial areas that failed to reproduce the multiple measured PFAS retention and transport data sets. In contrast, the new estimation methods produced interfacial areas that accurately represented air-water interfacial adsorption of PFAS and associated retention and transport. The measurement and estimation of air-water interfacial areas for field-scale applications is discussed in light of these results.
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Affiliation(s)
- Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, USA.
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6
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Hnatko JP, Liu C, Elsey JL, Dong S, Fortner JD, Pennell KD, Abriola LM, Cápiro NL. Microbial Reductive Dechlorination by a Commercially Available Dechlorinating Consortium Is Not Inhibited by Perfluoroalkyl Acids (PFAAs) at Field-Relevant Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37216485 DOI: 10.1021/acs.est.2c04815] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Perfluoroalkyl acids (PFAAs) have been shown to inhibit biodegradation (i.e., organohalide respiration) of chlorinated ethenes. The potential negative impacts of PFAAs on microbial species performing organohalide respiration, particularly Dehalococcoides mccartyi (Dhc), and the efficacy of in situ bioremediation are a critical concern for comingled PFAA-chlorinated ethene plumes. Batch reactor (no soil) and microcosm (with soil) experiments, containing a PFAA mixture and bioaugmented with KB-1, were completed to assess the impact of PFAAs on chlorinated ethene organohalide respiration. In batch reactors, PFAAs delayed complete biodegradation of cis-1,2-dichloroethene (cis-DCE) to ethene. Maximum substrate utilization rates (a metric for quantifying biodegradation rates) were fit to batch reactor experiments using a numerical model that accounted for chlorinated ethene losses to septa. Fitted values for cis-DCE and vinyl chloride biodegradation were significantly lower (p < 0.05) in batch reactors containing ≥50 mg/L PFAAs. Examination of reductive dehalogenase genes implicated in ethene formation revealed a PFAA-associated change in the Dhc community from cells harboring the vcrA gene to those harboring the bvcA gene. Organohalide respiration of chlorinated ethenes was not impaired in microcosm experiments with PFAA concentrations of 38.7 mg/L and less, suggesting that a microbial community containing multiple strains of Dhc is unlikely to be inhibited by PFAAs at lower, environmentally relevant concentrations.
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Affiliation(s)
- Jason P Hnatko
- Environmental Resources Management (ERM), Boston, Massachusetts 02108, United States
| | - Chen Liu
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Jack L Elsey
- Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Sheng Dong
- Department of Civil and Environmental Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - John D Fortner
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Kurt D Pennell
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Linda M Abriola
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Natalie L Cápiro
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
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Abraham JEF, Mumford KG, Patch DJ, Weber KP. Retention of PFOS and PFOA Mixtures by Trapped Gas Bubbles in Porous Media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15489-15498. [PMID: 36279175 DOI: 10.1021/acs.est.2c00882] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The transport of per- and polyfluoroalkyl substances (PFAS) in soil and groundwater is important for site investigation, risk characterization, and remediation planning. The adsorption of PFAS at air-water interfaces has been shown to significantly contribute to PFAS retention, with subsequent effects on concentrations and the time scales of transport. In this study, column experiments were conducted to investigate the transport of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) individually and in binary mixtures in the presence of a trapped gas phase, using clean sands to isolate adsorption to air-water interfaces. Consistent with previous studies, the transport of PFOS, PFOA, and 6:2 FTS was retarded by adsorption at the air-water interface, with greater retention of PFOS due to its higher affinity for the air-water interface. Chromatographic separation occurred in the experiments using binary mixtures of PFOS and PFOA, with greater retention at lower influent concentrations. The mixture experiments also showed enhanced breakthrough of PFOA in the presence of PFOS, where effluent concentrations of PFOA were temporarily greater than the influent concentration prior to the breakthrough of PFOS. This enhanced breakthrough was attributed to competition between PFOS and PFOA for adsorption to the air-water interface.
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Affiliation(s)
- Justine E F Abraham
- Department of Civil Engineering, Queen's University, Kingston, OntarioCanada, K7L 3N6
| | - Kevin G Mumford
- Department of Civil Engineering, Queen's University, Kingston, OntarioCanada, K7L 3N6
| | - David J Patch
- Environmental Sciences Group, Royal Military College of Canada, Kingston, OntarioCanada, 7K7 7B4
| | - Kela P Weber
- Environmental Sciences Group, Royal Military College of Canada, Kingston, OntarioCanada, 7K7 7B4
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Reif D, Zoboli O, Wolfram G, Amann A, Saracevic E, Riedler P, Hainz R, Hintermaier S, Krampe J, Zessner M. Pollutant source or sink? Adsorption and mobilization of PFOS and PFOA from sediments in a large shallow lake with extended reed belt. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 320:115871. [PMID: 36056490 DOI: 10.1016/j.jenvman.2022.115871] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 07/11/2022] [Accepted: 07/24/2022] [Indexed: 06/15/2023]
Abstract
In this study, we i) assessed the occurrence of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in sediments, pore water, and bulk water from three different areas in Lake Neusiedl, Austria, and ii) investigated mechanisms regulating adsorption and remobilization of these substances under different conditions via multiple lab-scale experiments. The adsorption capacity was mainly influenced by sediments' organic matter content, oxide composition, and pre-loading. Results suggest that a further increase of PFAS-concentrations in the open lake can be partly buffered by sediment transport to the littoral zone and adsorption to sediments in the extended reed belt. But, under current conditions, the conducted experiments revealed a real risk for mobilization of PFOS and PFOA from reed belt sediments that may lead to their transport back into the lake. The amount of desorbed PFAS is primarily dependent on water/sediment- or pore water/water-ratios and the concentration gradient. In contrast, water matrix characteristics and oxygen levels played a minor role in partitioning. The highest risk for remobilizing PFOS and PFOA was observed in experiments with sediments taken near the only major tributary to the lake (river Wulka), which had the highest pre-loading. The following management advice for water transport between high and low polluted areas can be derived based on the results. First, to reduce emissions into Lake waters from polluted tributaries like the Wulka river, we recommend diffuse pathways through the reed belt in the lake's littoral to reduce pollutant transport into the Lake and avoid high local sediment loadings. Second, water exchange with dried-up areas with probable higher loadings should be carefully handled and monitored to avoid critical back transport in the open lake. And third, general work in the reed belt or generally in the reed should be accompanied by monitoring to prevent uncontrolled remobilization in the future.
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Affiliation(s)
- D Reif
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria.
| | - O Zoboli
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria
| | - G Wolfram
- DWS Hydro-Ökologie GmbH, Zentagasse 47, 1050, Vienna, Austria
| | - A Amann
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria
| | - E Saracevic
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria
| | - P Riedler
- DWS Hydro-Ökologie GmbH, Zentagasse 47, 1050, Vienna, Austria
| | - R Hainz
- DWS Hydro-Ökologie GmbH, Zentagasse 47, 1050, Vienna, Austria
| | - S Hintermaier
- DWS Hydro-Ökologie GmbH, Zentagasse 47, 1050, Vienna, Austria
| | - J Krampe
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria
| | - M Zessner
- Institute for Water Quality and Resource Management- TU Wien; Karlsplatz 13/226-1, 1040, Vienna, Austria
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Brusseau ML, Guo B. PFAS concentrations in soil versus soil porewater: Mass distributions and the impact of adsorption at air-water interfaces. CHEMOSPHERE 2022; 302:134938. [PMID: 35568214 PMCID: PMC9667730 DOI: 10.1016/j.chemosphere.2022.134938] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/29/2022] [Accepted: 05/08/2022] [Indexed: 05/14/2023]
Abstract
Determining the risk posed by PFAS leaching from soil to groundwater requires quantification of the magnitude and temporal/spatial variability of PFAS mass discharge from the vadose zone, which is governed in part by the concentrations of PFAS in soil porewater. Porewater concentrations are impacted and mediated by the properties of the PFAS and soil, multiple transport and fate processes, and site conditions. The objective of this research was to delineate the relationship between soil porewater concentrations and soil concentrations, based on a comprehensive model of PFAS mass distribution within a soil sample volume. Measured parameters representing solid-phase sorption and air-water interfacial adsorption are used to illustrate the impact of soil and PFAS properties on the distribution of representative PFAS between soil and soil porewater. Literature data reported for soil and soil porewater concentrations of several PFAS obtained from outdoor lysimeter experiments are used to test the distribution model. Soil-to-porewater concentration ratios predicted with the model compared very well to the measured concentration ratios. The nondimensional distribution coefficient that describes the distribution of PFAS mass amongst all domains within a soil sample was observed to be a function of PFAS molecular size. Numerical simulations conducted for a model fire-training source area were used to illustrate the ranges in magnitude of soil versus porewater concentrations for representative field conditions. The results of the measured and simulated data sets demonstrated the importance of air-water interfacial adsorption for the distribution of the longer-chain PFAS within soil samples. PFAS soil porewater concentrations are anticipated to range from ng/L to mg/L depending upon soil concentrations, which in turn depend upon the nature of the site.
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Affiliation(s)
- M L Brusseau
- Environmental Science Department, The University of Arizona, Tucson, AZ, 85721, United States; Hydrology and Atmospheric Sciences Department, The University of Arizona, Tucson, AZ, 85721, United States.
| | - B Guo
- Hydrology and Atmospheric Sciences Department, The University of Arizona, Tucson, AZ, 85721, United States
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10
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Developing a QSPR Model of Organic Carbon Normalized Sorption Coefficients of Perfluorinated and Polyfluoroalkyl Substances. Molecules 2022; 27:molecules27175610. [PMID: 36080379 PMCID: PMC9457706 DOI: 10.3390/molecules27175610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/17/2022] Open
Abstract
Perfluorinated and polyfluoroalkyl substances (PFASs) are known for their long-distance migration, bioaccumulation, and toxicity. The transport of PFASs in the environment has been a source of increasing concerned. The organic carbon normalized sorption coefficient (Koc) is an important parameter from which to understand the distribution behavior of organic matter between solid and liquid phases. Currently, the theoretical prediction research on log Koc of PFASs is extremely limited. The existing models have limitations such as restricted application fields and unsatisfactory prediction results for some substances. In this study, a quantitative structure–property relationship (QSPR) model was established to predict the log Koc of PFASs, and the potential mechanism affecting the distribution of PFASs between two phases from the perspective of molecular structure was analyzed. The developed model had sufficient goodness of fit and robustness, satisfying the model application requirements. The molecular weight (MW) related to the hydrophobicity of the compound; lowest unoccupied molecular orbital energy (ELUMO) and maximum average local ionization energy on the molecular surface (ALIEmax), both related to electrostatic properties; and the dipole moment (μ), related to the polarity of the compound; are the key structural variables that affect the distribution behavior of PFASs. This study carried out a standardized modeling process, and the model dataset covered a comprehensive variety of PFASs. The model can be used to predict the log Koc of conventional and emerging PFASs effectively, filling the data gap of the log Koc of uncommon PFASs. The explanation of the mechanism of the model has proven to be of great value for understanding the distribution behavior and migration trends of PFASs between sediment/soil and water, and for estimating the potential environmental risks generated by PFASs.
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11
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Lyu Y, Wang B, Du X, Guo B, Brusseau ML. Air-water interfacial adsorption of C4-C10 perfluorocarboxylic acids during transport in unsaturated porous media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 831:154905. [PMID: 35364184 PMCID: PMC9645406 DOI: 10.1016/j.scitotenv.2022.154905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/23/2022] [Accepted: 03/25/2022] [Indexed: 05/11/2023]
Abstract
The impact of chain length on air-water interfacial adsorption of perfluorocarboxylic acids (PFCAs) during transport in unsaturated quartz sand was investigated. Short-chain (C4-C7: PFBA, PFPeA, PFHxA, PFHpA) and long chain (C8-C10: PFOA, PFNA, PFDA) PFCAs were selected as a representative homologous series. Surface tensions were measured to characterize surface activities of the selected PFCAs. Miscible-displacement column experiments were conducted for each of the PFCAs to characterize the magnitudes of air-water interfacial adsorption under transport conditions. The transport of the long-chain PFCAs exhibited greater retardation than the short-chain PFCAs. Air-water interfacial adsorption (AWIA) was the predominant source of retention (≥63%) for the long-chain PFCAs. Conversely, AWIA contributed less to retention than did solid-phase sorption for the short-chain PFCAs, with the former contributions ranging from 4% to 40%. Direct examination of the breakthrough-curve profiles as well as mathematical-modeling results demonstrated that transport of the two longest-chain PFCAs was influenced by nonlinear AWIA, whereas that of the shorter-chain PFCAs was not. This disparate behavior is consistent with the input concentration used for the transport experiments in comparison to the respective surface activities and critical reference concentrations of the different PFCAs. Quantitative-structure/property-relationship (QSPR) analysis was applied to characterize the influence of molecular size on air-water interfacial adsorption. The logs of the air-water interfacial adsorption coefficients (Kia) determined from the transport experiments are a monotonic function of molar volume, consistent with prior QSPR analyses of surface-tension measured values. The Kia values determined from the transport experiments are very similar to those measured from surface-tension data, indicating that the transport experiments produced robust measurements of AWIA.
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Affiliation(s)
- Ying Lyu
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026, PR China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130026, PR China; Institute of Water Resources and Environment, Jilin University, Changchun 130026, PR China.
| | - Baohua Wang
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026, PR China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130026, PR China
| | - Xinqiang Du
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026, PR China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130026, PR China
| | - Bo Guo
- Department of Hydrology and Atmospheric Sciences, University of Arizona, 429 Shantz Bldg., USA
| | - Mark L Brusseau
- Department of Hydrology and Atmospheric Sciences, University of Arizona, 429 Shantz Bldg., USA; Department of Environmental Science, University of Arizona, 429 Shantz Bldg., USA.
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12
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Johnson GR. PFAS in soil and groundwater following historical land application of biosolids. WATER RESEARCH 2022; 211:118035. [PMID: 35032876 DOI: 10.1016/j.watres.2021.118035] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 11/11/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
The land application of digested sewage sludge (biosolids) is widely employed across the globe. Studies show that biosolids contain significant amounts of inorganic and organic materials, as well as emerging pollutants, including per- and polyfluorinated alkyl substances (PFAS). With the wide range of pollutants commonly reported in biosolids, the potential risks associated with long-term land application operations are concerning. In this study, PFAS in surface soils, deeper soils into the vadose zone, and immediately-underlying groundwater was measured at an agricultural station with a long record of biosolids applications plus irrigation using treated wastewater. Twelve PFAS homologues were detected in every near surface soil sampled 0-30 cm depth below ground surface with multiple PFAS (especially short-chain) distributed through the soil profile. Average measured concentrations of PFAS in these soils suggest the soil burden PFOS>PFDA>PFOA for all substations sampled, independent of the historical loading rates and patterns of agricultural operations on those substations. Measured concentrations of PFOA and PFOS in the soil profile (0-90 cm) suggest these compounds have migrated to deeper soil depths (up to 9 m below the surface) with quantifiable concentrations in the soil and the immediate underlying groundwater located approximately 17 m below. Estimates of the total mass of PFAS in surface soils were effectively made using PFAS levels reported in sludges from the USEPA NSSS combined with long-term loading rates on record at the substations. With the land application of biosolids in the USA regulated by the USEPA, additional and updated risk assessments and surveys to include emerging pollutants such as PFAS are needed to protect public health and the environment.
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Affiliation(s)
- Gwynn R Johnson
- Civil and Environmental Engineering, Maseeh College of Engineering and Computer Science, Portland State University, Portland OR 97201, United States.
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13
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Huang D, Saleem H, Guo B, Brusseau ML. The impact of multiple-component PFAS solutions on fluid-fluid interfacial adsorption and transport of PFOS in unsaturated porous media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150595. [PMID: 34592291 PMCID: PMC8633151 DOI: 10.1016/j.scitotenv.2021.150595] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/17/2021] [Accepted: 09/22/2021] [Indexed: 05/29/2023]
Abstract
The objective of this research was to investigate the impact of multiple-component PFAS solutions on the retention of PFOS during transport in unsaturated porous media. Surface tensions were measured to characterize the impact of co-PFAS on the surface activity of PFOS. Miscible-displacement experiments were conducted to examine the air-water interfacial adsorption of PFOS during transport in single and multi-PFAS systems. Literature data for transport of PFOS in NAPL-water systems were also investigated for comparison. A mathematical model incorporating surfactant-induced flow, nonlinear rate-limited sorption, nonlinear rate-limited fluid-fluid interfacial adsorption, and competitive adsorption at the fluid-fluid interface was used to simulate the transport of PFOS. The results indicate that the presence of co-PFAS had no measurable impact on solid-phase sorption of PFOS during transport under the extant conditions of the experiments. Conversely, the air-water interfacial adsorption of PFOS was decreased by the presence of co-PFAS during transport under unsaturated-flow conditions for relatively high input concentrations. The multiple-component Langmuir model could not predict the competitive adsorption behavior observed during transport. Conversely, competitive interactions were not observed for transport with a lower input concentration. The results indicate that the retention and transport of individual PFAS in mixtures may in some cases be impacted by the presence of co-PFAS due to competitive fluid-fluid interfacial adsorption effects. Reduced retention due to competitive interfacial-adsorption interactions has the potential to decrease PFOS retardation during transport, thereby increasing migration rates in sources zones and enhancing groundwater-pollution risks. SYNOPSIS: The impact of PFAS mixtures on the retention and transport of PFOS in unsaturated porous media is examined with a series of experiments and mathematical modeling.
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Affiliation(s)
- Dandan Huang
- School of Water Resources & Environment, China University of Geosciences (Beijing), Beijing 100083, PR China; Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
| | - Hassan Saleem
- Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - Bo Guo
- Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States; Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States.
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14
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McDonough JT, Anderson RH, Lang JR, Liles D, Matteson K, Olechiw T. Field-Scale Demonstration of PFAS Leachability Following In Situ Soil Stabilization. ACS OMEGA 2022; 7:419-429. [PMID: 35036711 PMCID: PMC8756798 DOI: 10.1021/acsomega.1c04789] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/09/2021] [Indexed: 05/06/2023]
Abstract
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.
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Affiliation(s)
- Jeffrey T. McDonough
- Arcadis, 630 Plaza Drive
Suite 200, Highlands Ranch, Colorado 80129, United
States
- . Phone: 267-615-1863
| | - Richard H. Anderson
- Air
Force Civil Engineer Center (AFCEC), San Antonio, Texas 78056, United States
| | - Johnsie R. Lang
- Arcadis, 630 Plaza Drive
Suite 200, Highlands Ranch, Colorado 80129, United
States
| | - David Liles
- Arcadis, 630 Plaza Drive
Suite 200, Highlands Ranch, Colorado 80129, United
States
| | - Kasey Matteson
- Arcadis, 630 Plaza Drive
Suite 200, Highlands Ranch, Colorado 80129, United
States
| | - Theresa Olechiw
- Arcadis, 630 Plaza Drive
Suite 200, Highlands Ranch, Colorado 80129, United
States
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15
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Kabiri S, Tucker W, Navarro DA, Bräunig J, Thompson K, Knight ER, Nguyen TMH, Grimison C, Barnes CM, Higgins CP, Mueller JF, Kookana RS, McLaughlin MJ. Comparing the Leaching Behavior of Per- and Polyfluoroalkyl Substances from Contaminated Soils Using Static and Column Leaching Tests. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:368-378. [PMID: 34932318 DOI: 10.1021/acs.est.1c06604] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
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.
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Affiliation(s)
- Shervin Kabiri
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
| | - William Tucker
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
| | - Divina A Navarro
- CSIRO Land and Water, PMB 2, Glen Osmond, South Australia 5064, Australia
| | - Jennifer Bräunig
- Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Brisbane, Queensland 4102, Australia
| | - Kristie Thompson
- Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Brisbane, Queensland 4102, Australia
| | - Emma R Knight
- Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Brisbane, Queensland 4102, Australia
| | - Thi Minh Hong Nguyen
- Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Brisbane, Queensland 4102, Australia
| | | | - Craig M Barnes
- Airservices Australia, 25 Constitution Avenue, Canberra, Australian Capital Territory 2601, Australia
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Jochen F Mueller
- Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Brisbane, Queensland 4102, Australia
| | - Rai S Kookana
- CSIRO Land and Water, PMB 2, Glen Osmond, South Australia 5064, Australia
| | - Michael J McLaughlin
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
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16
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Huang D, Khan NA, Wang G, Carroll KC, Brusseau ML. The Co-Transport of PFAS and Cr(VI) in porous media. CHEMOSPHERE 2022; 286:131834. [PMID: 34392202 PMCID: PMC8634893 DOI: 10.1016/j.chemosphere.2021.131834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/23/2021] [Accepted: 08/05/2021] [Indexed: 05/06/2023]
Abstract
PFAS and Cr are present at some sites as co-contaminants. The objective of this research was to investigate the co-transport behavior of per- and polyfluoroalkyl substances (PFAS) and hexavalent chromium (Cr(VI)) in porous media. Miscible-displacement experiments were conducted using two soils and an aquifer sediment with different geochemical properties. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were employed as model PFAS. The retardation of PFOS was decreased in the presence of Cr(VI). Conversely, the transport and retardation of PFOA was not affected by the presence of Cr(VI). The reduction of PFOS retardation caused by Cr(VI) is likely due to sorption competition for both organic-carbon and inorganic (metal-oxides and clay minerals) domains. The relative contributions of the three soil constituents to PFOS sorption and the potential for competition between PFOS and Cr(VI) is a function of the geochemical composition of the porous media (i.e., organic carbon, metal-oxides and clay minerals). The PFAS had minimal impact on the retention and transport of Cr(VI). To our knowledge, the results presented herein represent the first reported data for PFOS and Cr(VI) co-transport in porous media. The results of this study indicate that the presence of Cr(VI) has the potential to increase the migration potential of PFOS in soil and groundwater, which should be considered when characterizing electroplating facilities, leather tanning facilities, and other co-contaminated sites.
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Affiliation(s)
- Dandan Huang
- School of Water Resources & Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China; Environmental Science Department, University of Arizona, Tucson, AZ, 85721, United States
| | - Naima A Khan
- Department of Plant & Environmental Sciences, New Mexico State University, MSC 3167, Las Cruces, NM, 88003-8001, United States
| | - Guangcai Wang
- School of Water Resources & Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China; MOE Key Laboratory of Groundwater Circulation and Environment Evolution & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Kenneth C Carroll
- Department of Plant & Environmental Sciences, New Mexico State University, MSC 3167, Las Cruces, NM, 88003-8001, United States
| | - Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ, 85721, United States.
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17
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Rovero M, Cutt D, Griffiths R, Filipowicz U, Mishkin K, White B, Goodrow S, Wilkin RT. Limitations of Current Approaches for Predicting Groundwater Vulnerability from PFAS Contamination in the Vadose Zone. GROUND WATER MONITORING & REMEDIATION 2021; 41:62-75. [PMID: 35087263 PMCID: PMC8788618 DOI: 10.1111/gwmr.12485] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/11/2021] [Indexed: 06/14/2023]
Abstract
Published literature for reported sorption coefficients (Kd) of eight anionic per- and polyfluoroalkyl substances (PFAS) in soil was reviewed. Kd values spanned three to five log units indicating that no single value would be appropriate for use in estimating PFAS impacts to groundwater using existing soil-water partition equations. Regression analysis was used to determine if the soil or solution parameters might be used to predict Kd values. None of the 15 experimental parameters collected could individually explain variability in reported Kd values. Significant associations between Kd and soil calcium and sodium content were found for many of the selected PFAS, suggesting that soil cation content may be critical to PFAS sorption, as previously noted in sources like Higgins and Luthy (2006), while organic carbon content was significant only at elevated levels (>5%). Unexplained discrepancies between the results from studies where PFAS were introduced to soil and desorbed in the laboratory and those that used material from PFAS-impacted sites suggest that laboratory experiments may be overlooking some aspects critical to PFAS sorption. Future studies would benefit from the development and use of standardized analytical methods to improve data quality and the establishment of soil parameters appropriate for collection to produce more complete data sets for predictive analysis.
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Affiliation(s)
- Matt Rovero
- Oak Ridge Associated Universities, U.S. Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Groundwater Characterization and Remediation Division, 919 Kerr Research Drive, Ada, OK 74820
| | - Diana Cutt
- U.S. Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Technical Support Coordination Division, 290 Broadway, New York, NY 10007
| | - Rachel Griffiths
- U.S. Environmental Protection Agency, Region 2, 290 Broadway, New York, NY 10007
| | - Urszula Filipowicz
- U.S. Environmental Protection Agency, Region 2, 290 Broadway, New York, NY 10007
| | - Katherine Mishkin
- U.S. Environmental Protection Agency, Region 3, 1650 Arch Street, Philadelphia, PA 19103
| | - Brad White
- U.S. Environmental Protection Agency, Region 3, 1650 Arch Street, Philadelphia, PA 19103
| | - Sandra Goodrow
- New Jersey Department of Environmental Protection, 428 East State Street, 1st Floor, Trenton, NJ 08625
| | - Richard T Wilkin
- U.S. Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Groundwater Characterization and Remediation Division, 919 Kerr Research Drive, Ada, OK 74820
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18
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Borthakur A, Wang M, He M, Ascencio K, Blotevogel J, Adamson DT, Mahendra S, Mohanty SK. Perfluoroalkyl acids on suspended particles: Significant transport pathways in surface runoff, surface waters, and subsurface soils. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126159. [PMID: 34229412 DOI: 10.1016/j.jhazmat.2021.126159] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/28/2021] [Accepted: 05/15/2021] [Indexed: 06/13/2023]
Abstract
Eroded particles from the source zone could transport a high concentration of perfluoroalkyl acids (PFAAs) to sediments and water bodies. Yet, the contribution of suspended particles has not been systematically reviewed. Analyzing reported studies, we quantitatively demonstrate that suspended particles in surface water can contain significantly higher concentrations of PFAAs than the sediment below, indicating the source of suspended particles are not the sediment but particles eroded and carried from the source zone upstream. The affinity of PFAAs to particles depends on the particle composition, including organic carbon fraction and iron or aluminum oxide content. In soils, most PFAAs are retained within the top 5 m below the ground surface. The distribution of PFAAs in the subsurface varies based on site properties and local weather conditions. The depth corresponding to the maximum concentration of PFAA in soil decreases with an increase in soil organic carbon or rainfall amount received in the catchment areas. We attribute a greater accumulation of PFAAs near the upper layer of the subsurface to an increase in the accumulation of particles eroded from source zones upstream receiving heavy rainfall. Precursor transformation in the aerobic zone is significantly higher than in the anaerobic zone, thereby making the aerobic subsurface zone serve as a long-term source of groundwater pollution. Collectively, these results suggest that suspended particles, often an overlooked vector for PFAAs, can be a dominant pathway for the transport of PFAAs in environments.
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Affiliation(s)
- Annesh Borthakur
- Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA.
| | - Meng Wang
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Meng He
- Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA
| | - Katia Ascencio
- Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA
| | - Jens Blotevogel
- Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO, USA
| | | | - Shaily Mahendra
- Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA
| | - Sanjay K Mohanty
- Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, USA.
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19
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Brusseau ML, Guo B, Huang D, Yan N, Lyu Y. Ideal versus Nonideal Transport of PFAS in Unsaturated Porous Media. WATER RESEARCH 2021; 202:117405. [PMID: 34273774 PMCID: PMC8559529 DOI: 10.1016/j.watres.2021.117405] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/23/2021] [Accepted: 06/30/2021] [Indexed: 05/11/2023]
Abstract
Per- and poly-fluoroalkyl substances (PFAS) adsorb at air-water interfaces during transport in unsaturated porous media. This can cause surfactant-induced flow and enhanced retention that is a function of concentration, which complicates characterization and modeling of PFAS transport under unsaturated conditions. The influence of surfactant-induced flow and nonlinear air-water interfacial adsorption (AWIA) on PFAS transport was investigated with a series of miscible-displacement transport experiments conducted with a several-log range in input concentrations. Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and ammonium perfluoro 2-methyl-3-oxahexanoate (GenX) were used as model PFAS. The results were interpreted in terms of critical reference concentrations associated with PFAS surface activities and their relationship to the relevancy of transport processes such as surfactant-induced flow and nonlinear AWIA for concentration ranges of interest. Analysis of the measured transport behavior of PFAS under unsaturated-flow conditions demonstrated that AWIA was linear when the input concentration was sufficiently below the critical reference concentration. This includes the absence of significant arrival-front self-sharpening and extended elution tailing of the breakthrough curves, as well as the similarity of retardation factors measured for a wide range of input concentrations. Independently-predicted simulations produced with a comprehensive flow and transport model that accounts for transient variably-saturated flow, surfactant-induced flow, nonlinear rate-limited solid-phase sorption, and nonlinear rate-limited AWIA provided excellent predictions of the measured transport. A series of simulations was conducted with the model to test the specific impact of various processes potentially influencing PFOS transport. The simulation results showed that surfactant-induced flow was negligible and that AWIA was effectively linear when the input concentration was sufficiently below the critical reference concentration. PFAS retention associated with AWIA can be considered to be ideal in such cases, thereby supporting the use of simplified mathematical models. Conversely, apparent nonideal transport behavior was observed for experiments conducted with input concentrations similar to or greater than the critical reference concentration.
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Affiliation(s)
- Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ, USA; Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA.
| | - Bo Guo
- Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA
| | - Dandan Huang
- Environmental Science Department, University of Arizona, Tucson, AZ, USA; School of Water Resources & Environment, China University of Geosciences, Beijing 100083, P.R. China
| | - Ni Yan
- Environmental Science Department, University of Arizona, Tucson, AZ, USA; Key Lab of Marine Environmental Science and Ecology, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
| | - Ying Lyu
- Environmental Science Department, University of Arizona, Tucson, AZ, USA; Key Lab of Groundwater Resources and Environment, Jilin Provincial Key Laboratory of Water Resources and Environment, and Institute of Water Resources and Environment, Jilin University, Changchun, 130026, PR China
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20
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Ji Y, Yan N, Brusseau ML, Guo B, Zheng X, Dai M, Liu H. Impact of a Hydrocarbon Surfactant on the Retention and Transport of Perfluorooctanoic Acid in Saturated and Unsaturated Porous Media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10480-10490. [PMID: 34288652 PMCID: PMC8634892 DOI: 10.1021/acs.est.1c01919] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The transport and retention behavior of perfluorooctanoic acid (PFOA) in the presence of a hydrocarbon surfactant under saturated and unsaturated conditions was investigated. Miscible-displacement transport experiments were conducted at different PFOA and sodium dodecyl sulfate (SDS) input ratios to determine the impact of SDS on PFOA adsorption at solid-water and air-water interfaces. A numerical flow and transport model was employed to simulate the experiments. The PFOA breakthrough curves for unsaturated conditions exhibited greater retardation compared to those for saturated conditions in all cases, owing to air-water interfacial adsorption. The retardation factor for PFOA with a low concentration of SDS (PFOA-SDS ratio of 10:1) was similar to that for PFOA without SDS under unsaturated conditions. Conversely, retardation was greater in the presence of higher levels of SDS (1:1 and 1:10) with retardation factors increasing from 2.4 to 2.9 and 3.6 under unsaturated conditions due to enhanced adsorption at the solid-water and air-water interfaces. The low concentration of SDS had no measurable impact on PFOA air-water interfacial adsorption coefficients (Kia) determined from the transport experiments. The presence of SDS at the higher PFOA-SDS concentration ratios increased the surface activity of PFOA, with transport-determined Kia values increased by 27 and 139%, respectively. The model provided very good independently predicted simulations of the measured breakthrough curves and showed that PFOA and SDS experienced various degrees of differential transport during the experiments. These results have implications for the characterization and modeling of poly-fluoroalkyl substances (PFAS) migration potential at sites wherein PFAS and hydrocarbon surfactants co-occur.
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Affiliation(s)
- Yifan Ji
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Ni Yan
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
- Corresponding author
| | - Mark L. Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
- DepartmentDepartment of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States
- Corresponding author
| | - Bo Guo
- DepartmentDepartment of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - Xilai Zheng
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Mengfan Dai
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Hejie Liu
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
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21
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Wang Y, Khan N, Huang D, Carroll KC, Brusseau ML. Transport of PFOS in aquifer sediment: Transport behavior and a distributed-sorption model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 779:146444. [PMID: 33740555 PMCID: PMC8565396 DOI: 10.1016/j.scitotenv.2021.146444] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/06/2021] [Accepted: 03/07/2021] [Indexed: 05/22/2023]
Abstract
The objectives of this research were to examine the transport of perfluorooctane sulfonic acid (PFOS) in aquifer sediment comprising different geochemical properties, and to compare the behavior to that observed for PFOS transport in soil and sand. PFOS retardation was relatively low for transport in all aquifer media. The PFOS breakthrough curves were asymmetrical and exhibited extensive concentration tailing, indicating that sorption/desorption was significantly nonideal. The results of model simulations indicated that rate-limited sorption/desorption was the primary cause of the nonideal PFOS transport. Comparison of PFOS transport in aquifer media to data reported for PFOS transport in two soils and a quartz sand showed that PFOS exhibited more extensive elution tailing for the soils, likely reflecting differences in the relative contributions of various media constituents to sorption. A three-component distributed-sorption model was developed that accounted for contributions from soil organic carbon, metal oxides, and silt + clay fraction. The model produced very good predictions of Kd for the five media with lower soil organic‑carbon contents (≤0.1%). Soil organic carbon was estimated to contribute 19-42% of the total sorption for all media except the sand, to which it contributed ~100%. The contribution of silt + clay ranged from 51 to 80% for all media except the sand. The only medium for which the contribution of metal-oxides was significant is Hanford, with an estimated contribution of 15%. Overall, the results of the study indicate that sorption of PFOS by these aquifer media comprised contributions from multiple soil constituents.
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Affiliation(s)
- Yake Wang
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, USA
| | - Naima Khan
- Department of Plant & Environmental Science, New Mexico State University, Las Cruces, NM 88003, USA; Water Science and Management Program, New Mexico State University, Las Cruces, NM 88003, USA
| | - Dandan Huang
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, USA; School of Water Resources & Environment, China University of Geosciences, Beijing 100083, PR China
| | - Kenneth C Carroll
- Department of Plant & Environmental Science, New Mexico State University, Las Cruces, NM 88003, USA; Water Science and Management Program, New Mexico State University, Las Cruces, NM 88003, USA
| | - Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, USA.
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22
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Turner LP, Kueper BH, Jaansalu KM, Patch DJ, Battye N, El-Sharnouby O, Mumford KG, Weber KP. Mechanochemical remediation of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) amended sand and aqueous film-forming foam (AFFF) impacted soil by planetary ball milling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 765:142722. [PMID: 33268250 DOI: 10.1016/j.scitotenv.2020.142722] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/23/2020] [Accepted: 09/26/2020] [Indexed: 06/12/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are manmade, fluorinated organic chemicals which have been identified as persistent organic pollutants. PFAS have surface active properties that have made them suitable for applications in oil- and water-resistant products, as well as many firefighting foams. No on-site remediation strategies exist to treat PFAS impacted soils. Mechanochemical remediation of PFOS- and PFOA-amended sand via a planetary ball mill was studied. The effect of sand mass, KOH as a co-milling reagent, and water saturation on the degradation of PFOA and PFOS was evaluated. By 4 h of milling concentrations were reduced by up to 98% for PFOS-amended dry sand and 99% for PFOA-amended dry sand without the addition of a co-milling reagent. Water saturation was determined to be a significant hindrance on the mechanochemical destruction of PFOS and PFOA. A maximum of 89% of fluoride was recovered from PFOS-amended sand when KOH was used as a co-milling reagent. It is hypothesized that reactive particles generated from the fracture of sand grains react with PFAS molecules to initiate destruction, which can result in full defluorination. Milling experiments were also conducted on soils from a Canadian firefighting training area (FFTA), demonstrating that PFOS concentrations can be reduced by up to 96% in site soils. For the first time, ball milling for the remediation of PFAS in environmental media has been demonstrated using amended sand and legacy soils from a FFTA.
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Affiliation(s)
- Lauren P Turner
- Department of Civil Engineering, Queen's University, Kingston, ON, Canada
| | - Bernard H Kueper
- Department of Civil Engineering, Queen's University, Kingston, ON, Canada
| | - Kevin M Jaansalu
- Environmental Sciences Group, Royal Military College of Canada, Kingston, ON, Canada
| | - David J Patch
- Environmental Sciences Group, Royal Military College of Canada, Kingston, ON, Canada
| | - Nick Battye
- Environmental Sciences Group, Royal Military College of Canada, Kingston, ON, Canada
| | | | - Kevin G Mumford
- Department of Civil Engineering, Queen's University, Kingston, ON, Canada
| | - Kela P Weber
- Department of Civil Engineering, Queen's University, Kingston, ON, Canada; Environmental Sciences Group, Royal Military College of Canada, Kingston, ON, Canada.
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23
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Van Glubt S, Brusseau ML. Contribution of Nonaqueous-Phase Liquids to the Retention and Transport of Per and Polyfluoroalkyl Substances (PFAS) in Porous Media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:3706-3715. [PMID: 33666425 PMCID: PMC8634874 DOI: 10.1021/acs.est.0c07355] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Per and polyfluoroalkyl substances (PFAS) cocontamination with nonaqueous-phase organic liquids (NAPLs) has been observed or suspected at various sites, particularly at fire-training areas at which aqueous film-forming foams (AFFFs) were applied. The objectives of this study are to (1) delineate the relative significance of specific PFAS-NAPL processes on PFAS retention, including partitioning into the bulk NAPL phase and adsorption to the NAPL-water interface; (2) investigate the influence of NAPL properties, saturation, and mass-transfer constraints on PFAS retention; and (3) determine whether PFAS may impact NAPL distribution through mobilization or dissolution. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are used as representative PFAS, and trichloroethene (TCE) and decane are used as representative NAPLs. NAPL-water interfacial adsorption was quantified with NAPL-water interfacial-tension measurements; partitioning into NAPL was quantified with batch experiments, and retardation factors (R) in the absence and presence of residual NAPL were determined with miscible-displacement transport experiments. R values increased in the presence of residual NAPL, with adsorption to the NAPL-water interface accounting for as much as ∼77% of retention and solid-phase adsorption also significantly contributing to retention. Additionally, this study provides the first QSPR analysis focused on NAPL-water interfacial adsorption coefficients, with results consistent with those from previous air-water studies. Lastly, this initial investigation into PFAS impacts on NAPL behavior determined that PFOS/PFOA are unlikely to enhance solubilization or mobilization of NAPL under the conditions present at many AFFF legacy sites.
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Affiliation(s)
- Sarah Van Glubt
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
| | - Mark L. Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
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24
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Sima MW, Jaffé PR. A critical review of modeling Poly- and Perfluoroalkyl Substances (PFAS) in the soil-water environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 757:143793. [PMID: 33303199 DOI: 10.1016/j.scitotenv.2020.143793] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/26/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
Due to their health effects and the recalcitrant nature of their CF bonds, Poly- and Perfluoroalkyl Substances (PFAS) are widely investigated for their distribution, remediation, and toxicology in ecosystems. However, very few studies have focused on modeling PFAS in the soil-water environment. In this review, we summarized the recent development in PFAS modeling for various chemical, physical, and biological processes, including sorption, volatilization, degradation, bioaccumulation, and transport. PFAS sorption is kinetic in nature with sorption equilibrium commonly quantified by either a linear, the Freundlich, or the Langmuir isotherms. Volatilization of PFAS depends on carbon chain length and ionization status and has been simulated by a two-layer diffusion process across the air water interface. First-order kinetics is commonly used for physical, chemical, and biological degradation processes. Uptake by plants and other biota can be passive and/or active. As surfactants, PFAS have a tendency to be sorbed or concentrated on air-water or non-aqueous phase liquid (NAPL)-water interfaces, where the same three isotherms for soil sorption are adopted. PFAS transport in the soil-water environment is simulated by solving the convection-dispersion equation (CDE) that is coupled to PFAS sorption, phase transfer, as well as physical, chemical, and biological transformations. As the physicochemical properties and concentration vary greatly among the potentially thousands of PFAS species in the environment, systematic efforts are needed to identify models and model parameters to simulate their fate, transport, and response to remediation techniques. Since many process formulations are empirical in nature, mechanistic approaches are needed to further the understanding of PFAS-soil-water-plant interactions so that the model parameters are less site dependent and more predictive in simulating PFAS remediation efficiency.
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Affiliation(s)
- Matthew W Sima
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Peter R Jaffé
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA.
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25
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Brusseau ML. Examining the robustness and concentration dependency of PFAS air-water and NAPL-water interfacial adsorption coefficients. WATER RESEARCH 2021; 190:116778. [PMID: 33387950 PMCID: PMC7856177 DOI: 10.1016/j.watres.2020.116778] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 05/19/2023]
Abstract
Determining robust values for the air-water or NAPL-water interfacial adsorption coefficient, KIA, is key to characterizing and modeling PFAS transport and fate in several environmental systems. Direct, high-resolution measurements of surfactant adsorption at the fluid-fluid interface were aggregated from the literature. This data set was used to examine the accuracy and applicability of Γ and KIA measurements determined for three PFAS from transport experiments and surface-tension data. The transport-measured Γ and KIA data were observed to be fully consistent with the directly-measured data. Specifically, Γ values for the two methods were entirely coincident in the region of overlapping concentrations, which spanned ~4 orders-of-magnitude. Furthermore, the two data sets adhered to an identical Γ-C profile. These results conclusively demonstrate the accuracy of the transport-measured values. Γ and KIA values determined from the application of the Gibbs adsorption equation to measured surface-tension data were fully consistent with the directly-measured and transport-measured data sets, demonstrating their applicability for representing PFAS transport in environmental systems. The directly-measured data were used to examine the concentration dependency of KIA values, absent the potential confounding effects associated with the use of surface-tension or transport-measured data. The directly-measured data clearly demonstrate that KIA attains a constant, maximum limit at lower concentrations. Two separate analyses of the transport-measured data both produced observations of constant KIA values at lower concentrations, consistent with the directly-measured data. These outcomes are discussed in terms of surface activities, relative surface coverages, and critical concentrations.
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Affiliation(s)
- Mark L Brusseau
- Environmental Science Department (Home) and Hydrology & Atmospheric Sciences Department (Joint), University of Arizona, Tucson, Arizona, United States.
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26
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Campos-Pereira H, Kleja DB, Sjöstedt C, Ahrens L, Klysubun W, Gustafsson JP. The Adsorption of Per- and Polyfluoroalkyl Substances (PFASs) onto Ferrihydrite Is Governed by Surface Charge. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15722-15730. [PMID: 33244971 PMCID: PMC7745537 DOI: 10.1021/acs.est.0c01646] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 10/30/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
An improved quantitative and qualitative understanding of the interaction of per- and polyfluoroalkyl substances (PFASs) and short-range ordered Fe (hydr)oxides is crucial for environmental risk assessment in environments low in natural organic matter. Here, we present data on the pH-dependent sorption behavior of 12 PFASs onto ferrihydrite. The nature of the binding mechanisms was investigated by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and by phosphate competition experiments. Sulfur K-edge XANES spectroscopy showed that the sulfur atom of the head group of the sulfonated PFASs retained an oxidation state of +V after adsorption. Furthermore, the XANES spectra did not indicate any involvement of inner-sphere surface complexes in the sorption process. Adsorption was inversely related to pH (p < 0.05) for all PFASs (i.e., C3-C5 and C7-C9 perfluorocarboxylates, C4, C6, and C8 perfluorosulfonates, perfluorooctane sulfonamide, and 6:2 and 8:2 fluorotelomer sulfonates). This was attributed to the pH-dependent charge of the ferrihydrite surface, as reflected in the decrease of surface ζ-potential with increasing pH. The importance of surface charge for PFAS adsorption was further corroborated by the observation that the adsorption of PFASs decreased upon phosphate adsorption in a way that was consistent with the decrease in ferrihydrite ζ-potential. The results show that ferrihydrite can be an important sorbent for PFASs with six or more perfluorinated carbons in acid environments (pH ≤ 5), particularly when phosphate and other competitors are present in relatively low concentrations.
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Affiliation(s)
- Hugo Campos-Pereira
- Department
of Soil and Environment, Swedish University
of Agricultural Sciences (SLU), P.O. Box 7014, SE-750 07 Uppsala, Sweden
| | - Dan B. Kleja
- Department
of Soil and Environment, Swedish University
of Agricultural Sciences (SLU), P.O. Box 7014, SE-750 07 Uppsala, Sweden
- Swedish
Geotechnical Institute (SGI), SE-581 93 Linköping, Sweden
| | - Carin Sjöstedt
- Department
of Soil and Environment, Swedish University
of Agricultural Sciences (SLU), P.O. Box 7014, SE-750 07 Uppsala, Sweden
| | - Lutz Ahrens
- Department
of Aquatic Sciences and Assessment, Swedish
University of Agricultural Sciences (SLU), P.O. Box 7014, SE-750 07 Uppsala, Sweden
| | - Wantana Klysubun
- Synchrotron
Light Research Institute, 111 Moo 6, Suranaree, Muang, Nakhon Ratchasima 30000, Thailand
| | - Jon Petter Gustafsson
- Department
of Soil and Environment, Swedish University
of Agricultural Sciences (SLU), P.O. Box 7014, SE-750 07 Uppsala, Sweden
- Department
of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, SE-100 44 Stockholm, Sweden
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27
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Brusseau ML, Taghap H. NAPL-water interfacial area as a function of fluid saturation measured with the interfacial partitioning tracer test method. CHEMOSPHERE 2020; 260:127562. [PMID: 32683025 PMCID: PMC7654436 DOI: 10.1016/j.chemosphere.2020.127562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 05/04/2023]
Abstract
The presence of organic immiscible liquids such as chlorinated solvents and fuels continues to be a primary source of risk for many hazardous waste sites. In this study, the standard miscible-displacement interfacial partitioning tracer test (IPTT) method was used for the first time to measure NAPL-water interfacial areas for a range of saturations. Multiple measurements were conducted for a natural quartz sand, with tetrachloroethene as the representative NAPL. The interfacial areas increased with decreasing water saturation. The measurements compared well to interfacial areas measured for the same sand with two alternative tracer methods, the mass-distribution batch method and the two-phase flow method. Measurements obtained with all three tracer-based methods exhibit a relatively large degree of variability. Thus, it is important to employ replication when using these methods. In contrast, interfacial areas measured with x-ray microtomography exhibit very small variability. However, the measured interfacial areas do not capture the contribution of surface-roughness to film-associated interfacial area. Each method has associated advantages and disadvantages, and it is important to be cognizant of them during their application.
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Affiliation(s)
- M L Brusseau
- Environmental Science Department, University of Arizona, USA.
| | - H Taghap
- Environmental Science Department, University of Arizona, USA
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28
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Schwichtenberg T, Bogdan D, Carignan CC, Reardon P, Rewerts J, Wanzek T, Field JA. PFAS and Dissolved Organic Carbon Enrichment in Surface Water Foams on a Northern U.S. Freshwater Lake. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14455-14464. [PMID: 33164508 DOI: 10.1021/acs.est.0c05697] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Information is needed on the concentration of per- and polyfluoroalkyl substances (PFAS) in foams on surface waters impacted by aqueous film-forming foam (AFFF). Nine pairs of foam and underlying bulk water were collected from a single freshwater lake impacted by PFAS and analyzed for PFAS by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF) and for dissolved organic carbon (DOC). The DOC of two foam:bulk water pairs was characterized by 1H NMR. Foams were comprised of 16 PFAS with concentrations as high as 97 000 ng/L (PFOS) along with longer-chain, more hydrophobic PFAS. Only five PFAS (PFOS and shorter chain lengths) were quantified in underlying bulk waters. Enrichment factors (foam:bulk water) ranged from 10 (PFHxA) up to 2830 (PFOS). Foams impacted by AFFF gave the greatest concentrations and number of PFAS classes with PFOS concentrations exceeding the EPA health advisory level (70 ng/L). PFAS concentrations were significantly below published critical micelle concentrations and constituted <0.1% of overall DOC concentrations in foam, indicating that PFAS are a minor fraction of DOC and that DOC likely plays a central role in foam formation. Estimates indicate that foam ingestion is a potentially important route of exposure for children and adults when they are in surface waters where foam is present.
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Affiliation(s)
- Trever Schwichtenberg
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Dorin Bogdan
- AECOM, Grand Rapids, Michigan 49546, United States
| | - Courtney C Carignan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Patrick Reardon
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Justin Rewerts
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Thomas Wanzek
- Crop and Soil Science, Oregon State University, Corvallis, Oregon 97331, United States
| | - Jennifer A Field
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331, United States
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29
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Brusseau ML, Anderson RH, Guo B. PFAS concentrations in soils: Background levels versus contaminated sites. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 740:140017. [PMID: 32927568 PMCID: PMC7654437 DOI: 10.1016/j.scitotenv.2020.140017] [Citation(s) in RCA: 243] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 04/13/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are contaminants of critical concern due to their persistence, widespread distribution in the environment, and potential human-health impacts. In this work, published studies of PFAS concentrations in soils were compiled from the literature. These data were combined with results obtained from a large curated database of PFAS soil concentrations for contaminated sites. In aggregate, the compiled data set comprises >30,000 samples collected from >2500 sites distributed throughout the world. Data were collected for three types of sites- background sites, primary-source sites (fire-training areas, manufacturing plants), and secondary-source sites (biosolids application, irrigation water use). The aggregated soil-survey reports comprise samples collected from all continents, and from a large variety of locations in both urban and rural regions. PFAS were present in soil at almost every site tested. Low but measurable concentrations were observed even in remote regions far from potential PFOS sources. Concentrations reported for PFAS-contaminated sites were generally orders-of-magnitude greater than background levels, particularly for PFOS. Maximum reported PFOS concentrations ranged upwards of several hundred mg/kg. Analysis of depth profiles indicates significant retention of PFAS in the vadose zone over decadal timeframes and the occurrence of leaching to groundwater. It is noteworthy that soil concentrations reported for PFAS at contaminated sites are often orders-of-magnitude higher than typical groundwater concentrations. The results of this study demonstrate that PFAS are present in soils across the globe, and indicate that soil is a significant reservoir for PFAS. A critical question of concern is the long-term migration potential to surface water, groundwater, and the atmosphere. This warrants increased focus on the transport and fate behavior of PFAS in soil and the vadose zone, in regards to both research and site investigations.
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Affiliation(s)
- Mark L Brusseau
- Department of Environmental Science, University of Arizona, Tucson, AZ, USA; Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA.
| | | | - Bo Guo
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA
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30
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Yan N, Ji Y, Zhang B, Zheng X, Brusseau ML. Transport of GenX in Saturated and Unsaturated Porous Media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11876-11885. [PMID: 32972138 PMCID: PMC7654438 DOI: 10.1021/acs.est.9b07790] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The objective of this research was to investigate the retention and transport behavior of GenX in five natural porous media with similar median grain diameters but different geochemical properties. Surface tensions were measured to characterize surface activity. Miscible-displacement experiments were conducted under saturated conditions to characterize the magnitude of solid-phase adsorption, while unsaturated-flow experiments were conducted to examine the impact of air-water interfacial adsorption on retention and transport. The results from surface-tension measurements showed that the impact of solution composition is greater for the ammonium form of GenX than for the acid form, due to the presence of the NH4 counterion. The breakthrough curves for the experiments conducted under saturated conditions were asymmetrical, and a solute-transport model employing a two-domain representation of nonlinear, rate-limited sorption provided reasonable simulations of the measured data. The magnitudes of solid-phase adsorption were relatively small, with the highest adsorption associated with the medium containing the greatest amount of metal oxides. The breakthrough curves for the experiments conducted under unsaturated conditions exhibited greater retardation due to the impact of adsorption at the air-water interface. The contributions of air-water interfacial adsorption to GenX retention ranged from ∼24% to ∼100%. The overall magnitudes of retardation were relatively low, with retardation factors < ∼3, indicating that GenX has significant migration potential in soil and the vadose zone. To our knowledge, the results presented herein represent the first reported data for solid-water and air-water interfacial adsorption of GenX by soil. These data should prove useful for assessing the transport and fate behavior of GenX in soil and groundwater.
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Affiliation(s)
- Ni Yan
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, P.R. China
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
| | - Yifan Ji
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
| | - Bohan Zhang
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
| | - Xilai Zheng
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, P.R. China
| | - Mark L. Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, United States
- Corresponding author,
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31
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Abstract
The HYDRUS unsaturated flow and transport model was modified to simulate the effects of non-linear air-water interfacial (AWI) adsorption, solution surface tension-induced flow, and variable solution viscosity on the unsaturated transport of per- and polyfluoroalkyl substances (PFAS) within the vadose zone. These modifications were made and completed between March 2019 and May 2019, and were implemented into both the one-dimensional (1D) and two-dimensional (2D) versions of HYDRUS. Herein, the model modifications are described and validated against the available literature-derived PFAS transport data (i.e., 1D experimental column transport data). The results of both 1D and 2D example simulations are presented to highlight the function and utility of the model to capture the dynamic and transient nature of the temporally and spatially variable interfacial area of the AWI (Aaw) as it changes with soil moisture content (Θw) and how it affects PFAS unsaturated transport. Specifically, the simulated examples show that while AWI adsorption of PFAS can be a significant source of retention within the vadose zone, it is not always the dominant source of retention. The contribution of solid-phase sorption can be considerable in many PFAS-contaminated vadose zones. How the selection of an appropriate Aaw(Θw) function can impact PFAS transport and how both mechanisms contribute to PFAS mass flux to an underlying groundwater source is also demonstrated. Finally, the effects of soil textural heterogeneities on PFAS unsaturated transport are demonstrated in the results of both 1D and 2D example simulations.
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32
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Lyu Y, Brusseau ML. The influence of solution chemistry on air-water interfacial adsorption and transport of PFOA in unsaturated porous media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 713:136744. [PMID: 32019053 PMCID: PMC7654434 DOI: 10.1016/j.scitotenv.2020.136744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/12/2020] [Accepted: 01/14/2020] [Indexed: 05/19/2023]
Abstract
There is great interest in the transport behavior of PFAS in the vadose zone, and the impact of leaching on groundwater contamination. Air-water interfacial adsorption is an important process for PFAS retention in unsaturated porous media, and it is influenced by many factors including solution conditions such as ionic strength. The present study employed miscible-displacement column experiments to investigate the impact of ionic strength and pH on perfluorooctanoic acid (PFOA) retardation and transport under dynamic water-flow conditions. The results showed that retardation under unsaturated conditions was affected significantly by changes in ionic strength, whereas there was minimal impact for saturated conditions. This indicates that air-water interfacial adsorption, which was a major source of retardation, was influenced significantly by changes in ionic strength while they had a minor impact on solid-phase adsorption. The impact of changes in ionic strength on the magnitude of air-water interfacial adsorption observed for the column experiments was consistent with measured surface-tension data. The impact of changes in pH was less significant compared to that of ionic strength for transport under unsaturated conditions. These results illustrate the influence of solution chemistry on PFAS adsorption and transport under unsaturated conditions. This solution-dependent behavior should be considered when characterizing PFAS transport in soils and the vadose zone.
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Affiliation(s)
- Ying Lyu
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, 130026, PR China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun, 130026, PR China; Institute of Water Resources and Environment, College of Construction Engineering, Jilin University, Changchun, 130026, PR China
| | - Mark L Brusseau
- Environmental Science Department, Hydrology and Atmospheric Sciences Department, 429 Shantz Bldg, University of Arizona, United States of America.
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Meng P, Jiang X, Wang B, Huang J, Wang Y, Yu G, Cousins IT, Deng S. Role of the air-water interface in removing perfluoroalkyl acids from drinking water by activated carbon treatment. JOURNAL OF HAZARDOUS MATERIALS 2020; 386:121981. [PMID: 31896003 DOI: 10.1016/j.jhazmat.2019.121981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/16/2019] [Accepted: 12/25/2019] [Indexed: 06/10/2023]
Abstract
Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) is a worldwide problem. In this study, we for the first time revealed the role of the air-water interface in enhancing the removal of long-chain perfluoroalkyl carboxylic (PFCAs; CnF2n+1COOH, n ≥ 7) and perfluoroalkane sulfonic (PFSAs; CnF2n+1SO3H, n ≥ 6) acids, collectively termed as perfluoroalkyl acids (PFAAs), through combined aeration and adsorption on two kinds of activated carbon (AC). Aeration was shown to enhance the removal of long-chain PFAAs through adsorption at the air-water interface and subsequent adsorption of PFAA-enriched air bubbles to the AC. The removal of selected long-chain PFAAs was increased by 50-115 % with the assistance of aeration, depending on the perfluoroalkyl chain length. Aeration is more effective in enhancing long-chain PFAA removal as air-water interface adsorption increases with PFAA chain length due to higher surface activity. After removing adsorbed air bubbles by centrifugation, up to 80 % of the long-chain PFAAs were able to desorb from the sorbent, confirming the contribution of the air-water interface to the adsorption of PFAAs on AC. Aeration during AC treatment of water could enhance the removal of long-chain PFAAs, and improve the performance of AC during water treatment.
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Affiliation(s)
- Pingping Meng
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China; Department of Civil, Construction and Environmental Engineering, North Carolina State University, Raleigh, NC, 27695, United States
| | - Xiangzhe Jiang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Bin Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jun Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Yujue Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Gang Yu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Ian T Cousins
- Department of Environmental Science and Analytical Chemistry (ACES), Stockholm University, SE-106 91, Stockholm, Sweden.
| | - Shubo Deng
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China.
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Guo B, Zeng J, Brusseau ML. A Mathematical Model for the Release, Transport, and Retention of Per- and Polyfluoroalkyl Substances (PFAS) in the Vadose Zone. WATER RESOURCES RESEARCH 2020; 56:e2019WR026667. [PMID: 33223573 PMCID: PMC7673302 DOI: 10.1029/2019wr026667] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/09/2020] [Indexed: 05/19/2023]
Abstract
Per- and Polyfluoroalkyl Substances (PFAS) are emerging contaminants of critical concern. As surfactants, PFAS tend to accumulate at air-water interfaces and may stay in the vadose zone for long times before contaminating groundwater. Yet not well understood, the extent of retention in the vadose zone has critical implications for risk management and remediation strategies. We present the first mathematical model that accounts for surfactant-induced flow and solid-phase and air-water interfacial adsorption. We apply the model to simulate PFOS (a PFAS compound of primary concern) transport in the vadose zone at a model fire-training area site impacted by Aqueous Film-Forming Foam (AFFF). Air-water interfacial adsorption is shown to have a significant impact-amplified by the low water content due to gravity drainage-total retardation factors range from 233 to 1355 for the sand and 146 to 792 for the soil used in the study. The simulations illustrate it can take several decades or longer for PFOS to reach groundwater. Counterintuitively, the lower water content in the sand-due to stronger drainage and weaker capillary retention-leads to retardation factors greater than for the soil. Also, most PFOS is adsorbed at air-water interfaces with only 1-2% in the aqueous phase. The implications include 1) fine-texture materials could have lower retardation factors than sand due to higher retained water content, 2) soil PFAS concentrations are likely to be orders of magnitude higher than those in groundwater at source zones. Both implications are consistent with recent field observations at hundreds of AFFF-impacted sites.
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Affiliation(s)
- Bo Guo
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA
| | - Jicai Zeng
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA
| | - Mark L. Brusseau
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA
- Department of Environmental Science, University of Arizona, Tucson, Arizona, USA
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Brusseau ML. Simulating PFAS transport influenced by rate-limited multi-process retention. WATER RESEARCH 2020; 168:115179. [PMID: 31639593 PMCID: PMC6957125 DOI: 10.1016/j.watres.2019.115179] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 05/19/2023]
Abstract
The transport of per- and poly-fluoroalkyl substances (PFAS) in the vadose zone is complicated by the fact that multiple mass-transfer processes can contribute to their retention and retardation. In addition, PFAS transport at some sites can be further complicated by the presence of organic immiscible liquids (OIL). Mass-transfer processes are inherently rate limited and, therefore, have the potential to cause nonideal transport of PFAS. The objectives of this research were to: (1) develop a solute-transport model that explicitly accounts for multiple retention processes, including adsorption at air-water and OIL-water interfaces, adsorption by the solid phase, and diffusive mass-transfer between advective and nonadvective domains, and (2) apply the model to measured transport data to delineate which processes are rate limited and contribute to observed nonideal transport. Breakthrough curves for transport of two PFAS and one hydrocarbon surfactant in sand obtained from prior miscible-displacement experiments exhibited nonideal transport. The multiprocess model effectively simulated the measured transport data. The results of the analyses indicate that adsorption at the air-water and OIL-water interface can generally be treated as effectively instantaneous for transport in porous media. The rate limitations associated with solid-phase adsorption and diffusive mass transfer between advective and nonadvective domains were of greater significance.
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Affiliation(s)
- Mark L Brusseau
- Department of Environmental Science, University of Arizona, USA.
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