Alunite Supergroup Mineral Formation in Soil Decreases Lead and Arsenic Bioavailability: A Path Towards Concomitant Remediation
Citation:
Sowers, T., M. Blackmon, R. Karna, Matthew Noerpel, A. Betts, G. Diamond, D. Thomas, K. Bradham, AND K. Scheckel. Alunite Supergroup Mineral Formation in Soil Decreases Lead and Arsenic Bioavailability: A Path Towards Concomitant Remediation. American Chemical Society Meeting, New Orleans, LA, March 17 - 21, 2024.
Impact/Purpose:
Invited presentation to the American Chemical Society Meeting providing an overview of the group's plumbojarosite research effort. Lead (Pb) and arsenic (As) contamination of soils is widespread in the United States and is an important source of exposure in young children. Early life exposure to metal(loid) contaminants has serious and long-lasting effects on health, making mitigation a critical public health goal. Removal/replacement of contaminated soils is often used to reduce exposure; however, this approach can be economically and logistically impractical. An alternative approach to reduce exposure through ingestion of contaminated soil involves the conversion of soil Pb/As species into forms that are less likely to cross the gastrointestinal tract (GIT) barrier when ingested. We recently developed a novel co-contaminant soil treatment technique, stemming from unique observations at a Superfund site, that promotes formation of plumbojarosite (PLJ). Conversion of soil Pb to PLJ drastically reduces Pb relative bioavailability by >90%, decreasing the amount of ingested soil Pb that crosses the GIT barrier. However, we continue to fine tune options to promote mineral transformation and questions remain as to how Pb and/or PLJ interact with elements as soil moves through the GIT. Here, we examined properties of pre- and post-treatment soils using heat-dependent PLJ precipitation methods and a newly developed K-jarosite seeding treatment that is conducted at ambient temperature, while also assessing treatment impacts on both Pb and As sequestration. Bulk and spatially-resolved X-ray absorption spectroscopy revealed that both treatments were effective at converting Pb and As contaminated soil to low bioaccessibility/bioavailability PLJ. These results suggest that jarosite-conversion techniques are a promising option for soil Pb and As remediation; however, further investigation applying these chemical techniques in field conditions is needed to assess long-term efficacy and suitability.
Description:
Lead (Pb) and arsenic (As) contamination of soils is widespread in the United States and is an important source of exposure in young children. Early life exposure to metal(loid) contaminants has serious and long-lasting effects on health, making mitigation a critical public health goal. Removal/replacement of contaminated soils is often used to reduce exposure; however, this approach can be economically and logistically impractical. An alternative approach to reduce exposure through ingestion of contaminated soil involves the conversion of soil Pb/As species into forms that are less likely to cross the gastrointestinal tract (GIT) barrier when ingested. We recently developed a novel co-contaminant soil treatment technique, stemming from unique observations at a Superfund site, that promotes formation of plumbojarosite (PLJ). Conversion of soil Pb to PLJ drastically reduces Pb relative bioavailability by >90%, decreasing the amount of ingested soil Pb that crosses the GIT barrier. However, we continue to fine tune options to promote mineral transformation and questions remain as to how Pb and/or PLJ interact with elements as soil moves through the GIT. Here, we examined properties of pre- and post-treatment soils using heat-dependent PLJ precipitation methods and a newly developed K-jarosite seeding treatment that is conducted at ambient temperature, while also assessing treatment impacts on both Pb and As sequestration. Bulk and spatially-resolved X-ray absorption spectroscopy revealed that both treatments were effective at converting Pb and As contaminated soil to low bioaccessibility/bioavailability PLJ. These results suggest that jarosite-conversion techniques are a promising option for soil Pb and As remediation; however, further investigation applying these chemical techniques in field conditions is needed to assess long-term efficacy and suitability.