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Sowers TD, Blackmon MD, Betts AR, Jerden ML, Scheckel KG, Bradham KD. Potassium jarosite seeding of soils decreases lead and arsenic bioaccessibility: A path toward concomitant remediation. Proc Natl Acad Sci U S A 2023; 120:e2311564120. [PMID: 38048468 PMCID: PMC10723135 DOI: 10.1073/pnas.2311564120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/23/2023] [Indexed: 12/06/2023] Open
Abstract
Soils are common sources of metal(loid) contaminant exposure globally. Lead (Pb) and arsenic (As) are of paramount concern due to detrimental neurological and carcinogenic health effects, respectively. Pb and/or As contaminated soils require remediation, typically leading to excavation, a costly and environmentally damaging practice of removing soil to a central location (e.g., hazardous landfill) that may not be a viable option in low-income countries. Chemical remediation techniques may allow for in situ conversion of soil contaminants to phases that are not easily mobilized upon ingestion; however, effective chemical remediation options are limited. Here, we have successfully tested a soil remediation technology using potted soils that relies on converting soil Pb and As into jarosite-group minerals, such as plumbojarosite (PLJ) and beudantite, possessing exceptionally low bioaccessibility [i.e., solubility at gastric pH conditions (pH 1.5 to 3)]. Across all experiments conducted, all new treatment methods successfully promoted PLJ and/or beudantite conversion, resulting in a proportional decrease in Pb and As bioaccessibility. Increasing temperature resulted in increased conversion to jarosite-group minerals, but addition of potassium (K) jarosite was most critical to Pb and As bioaccessibility decreases. Our methods of K-jarosite treatment yielded <10% Pb and As bioaccessibility compared to unamended soil values of approximately 70% and 60%, respectively. The proposed treatment is a rare dual remediation option that effectively treats soil Pb and As such that potential exposure is considerably reduced. Research presented here lays the foundation for ongoing field application.
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Affiliation(s)
- Tyler D. Sowers
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
| | - Matthew D. Blackmon
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
| | - Aaron R. Betts
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH45268
| | | | - Kirk G. Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH45268
| | - Karen D. Bradham
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
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Sowers TD, Blackmon MD, Bone SE, Kirby AM, Jerden ML, Noerpel MR, Scheckel KG, Bradham KD. Successful Conversion of Pb-Contaminated Soils to Low-Bioaccessibility Plumbojarosite Using Potassium-Jarosite at Ambient Temperature. Environ Sci Technol 2022; 56:15718-15727. [PMID: 36239028 PMCID: PMC10398550 DOI: 10.1021/acs.est.2c05606] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Methods promoting lead (Pb) phase transformation in soils are essential for decreasing Pb bioaccessibility/bioavailability and may offer an in situ, cost-efficient process for mitigating contaminant exposure. Recent plumbojarosite (PLJ) conversion methods have shown the greatest potential to reduce soil Pb bioaccessibility, an in vitro bioaccessibility assay measurement of the proportion of Pb solubilized under gastric chemical conditions. Soils tested utilizing the recent PLJ method were found to have a Pb bioaccessibility of <1%, compared to original soils possessing bioaccessibility of >70%. However, this technique requires heat (95-100 °C) to promote mineral transformation. Jarosite-group minerals may incorporate multiple interlayer cations; therefore, we probed the potential for jarosite to remediate Pb via intercalation by reacting presynthesized potassium (K)-jarosite with aqueous Pb and/or Pb-contaminated soil at room temperature. Both K-jarosite and heated PLJ-treated samples were investigated by pairing bioaccessibility analyses with advanced bulk and spatially resolved X-ray absorption spectroscopy analyses. Samples treated with K-jarosite promoted Pb transformation to low-bioaccessibility (<10%) PLJ, with soil being converted to 100% PLJ using both heated and nonheated techniques. μ-X-ray fluorescence (μ-XRF) and μ-X-ray absorption near-edge structure (μ-XANES) showcase significant differences between elemental interactions for heated and nonheated PLJ-treated samples with anglesite impurities being found on the microscale. Although further development is necessary to accommodate for suitable field conditions, results indicate, for the first time, that K-jarosite may successfully convert soil Pb to PLJ without high-temperature conditions. The newfound utility of K-jarosite is expected to be key to future jarosite-based soil Pb remediation method development.
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Affiliation(s)
- Tyler D Sowers
- Center of Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Matthew D Blackmon
- Center of Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Sharon E Bone
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Alicia M Kirby
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, United States
| | - Marissa L Jerden
- Jacobs Technology, Inc., 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711, United States
| | - Matthew R Noerpel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Kirk G Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Karen D Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
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Sowers TD, Nelson CM, Blackmon MD, Jerden ML, Kirby AM, Diamond GL, Bradham KD. Interconnected soil iron and arsenic speciation effects on arsenic bioaccessibility and bioavailability: a scoping review. J Toxicol Environ Health B Crit Rev 2022; 25:1-22. [PMID: 34706629 PMCID: PMC9850428 DOI: 10.1080/10937404.2021.1996499] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Extensive research has examined arsenic (As) bioavailability in contaminated soils and is routinely assessed using in vitro bioaccessibility (IVBA) assays. Analysis of differences in bioaccessibility measurements across IVBA assays and phases is expected to provide valuable insights into geochemical mechanisms controlling soil As bioaccessibility and bioavailability. Soil iron (Fe) content and As speciation are expected to significantly influence IVBA gastric and intestinal phases due to fluctuations in precipitation-dissolution chemistry and sorption reactivity as pH and assay chemical complexity changes. The aim of this review was to examine these relationships by 1) conducting a meta-analysis (n = 47 soils) determining the influence of total Fe on As bioaccessibility measurements and 5 IVBA assays and 2) investigating the effect of As speciation on gastric/intestinal phase IVBA and in vitro-in vivo correlations. Our findings indicate that soil Fe content and As speciation heterogeneity are important in elucidating variability of bioaccessibility measurements across IVBA assays and gastrointestinal phases. Greater focus on coupled As speciation and Fe precipitation chemistry may (1) improve our understanding of soil geochemical factors and assay constituents that influence As in vitro-in vivo correlations and (2) resolve variability in the precision of oral relative bioavailability (RBA) estimated using IVBA assays for soils possessing heterogenous As speciation and Fe composition.
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Affiliation(s)
- Tyler D Sowers
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC, US
| | | | - Matthew D Blackmon
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC, US
| | | | | | | | - Karen D Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC, US
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Sowers TD, Nelson CM, Diamond GL, Blackmon MD, Jerden ML, Kirby AM, Noerpel MR, Scheckel KG, Thomas DJ, Bradham KD. High Lead Bioavailability of Indoor Dust Contaminated with Paint Lead Species. Environ Sci Technol 2021; 55:402-411. [PMID: 33307690 PMCID: PMC8204915 DOI: 10.1021/acs.est.0c06908] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
House dust and soils can be major sources of lead (Pb) exposure for children. The American Healthy Homes Survey (AHHS) was developed to estimate Pb exposure from house dust and soil, in addition to other potential household contaminants and allergens. We have combined X-ray absorption spectroscopic (XAS) fingerprinting and in vivo mouse relative bioavailability (RBA) measurements for a subset of house dust and residential soils collected in the AHHS, with the primary objective of gaining a better understanding of determinants of house dust Pb bioavailability. Lead speciation was well related to variations in RBA results and revealed that highly bioavailable Pb (hydroxy)carbonate (indicative of Pb-based paint) was the major Pb species present in house dusts. Measured Pb RBA was up to 100% and is likely driven by paint Pb. To our knowledge, this is the first report of in vivo Pb RBA for U.S. house dust contaminated in situ with paint Pb and corroborates results from a previous study that demonstrated high RBA of paint Pb added to soil. We also report a relatively low RBA (23%) in a residential soil where the major Pb species was found to be plumbojarosite, consistent with a previous report that plumbojarosite lowers Pb RBA in soils.
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Affiliation(s)
- Tyler D. Sowers
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Clay M. Nelson
- SRC, Inc., North Syracuse, New York 13212, United States
| | | | - Matt D. Blackmon
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Marissa L. Jerden
- Jacobs Technology, Inc., 109 T.W. Alexander Drive, RTP, North Carolina 27711, US
| | - Alicia M. Kirby
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, US
| | - Matthew R. Noerpel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, US
| | - Kirk G. Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, US
| | - David J. Thomas
- Center for Computational Toxicology & Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Karen D. Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
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