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Successful Conversion of Pb-Contaminated Soils to Low-Bioaccessibility Plumbojarosite Using Potassium-Jarosite at Ambient Temperature
Citation:
Sowers, T., M. Blackmon, S. Bone, A. Kirby, M. Jerden, Matthew Noerpel, K. Scheckel, AND K. Bradham. Successful Conversion of Pb-Contaminated Soils to Low-Bioaccessibility Plumbojarosite Using Potassium-Jarosite at Ambient Temperature. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 56(22):15718-15727, (2022). https://doi.org/10.1021/acs.est.2c05606
Impact/Purpose:
We showcase the potential for K-jarosite to treat lead-contaminated soils to form plumbojarosite, a Pb mineral of very low bioavailability. This study confirms that plumbojarosite significantly decreased Pb relative bioavailability, making this an exceptionally promising remediation technology. A primary barrier to our early research involving plumbojarosite formation was high temperature requirements for the treatment to function (95-100°C); however, our newly developed K-jarosite method may be performed at room temperature conditions. These findings further ORD’s research on development of soil remediation technologies to reduce lead bioavailability at contaminated sites in support of EPA’s OLEM/OSRTI and Regional offices. ORD’s soil remediation research for lead contaminated soils is listed as a high priority research need for OLEM/OSRTI and EPA Regional offices.
Description:
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.
URLs/Downloads:
DOI: Successful Conversion of Pb-Contaminated Soils to Low-Bioaccessibility Plumbojarosite Using Potassium-Jarosite at Ambient Temperature
https://pubmed.ncbi.nlm.nih.gov/36239028/