Bioavailable soil Pb minimized by in situ transformation to plumbojarosite

Abstract

Exposure to lead (Pb) during early life has persistent adverse health effects. During childhood, ingestion of bioavailable Pb in contaminated soils can be a major route of Pb absorption. Remediation to alter physiochemical properties of soil-borne Pb can reduce Pb bioavailability. Our laboratory-based approach for soil Pb remediation uses addition of iron (Fe) sulfate and application of heat to promote formation of plumbojarosite (PLJ), a sparingly soluble Pb-Fe hydroxysulfate mineral. We treated two soils with anthropogenic Pb contamination and samples of clean topsoil spiked with various Pb compounds (i.e., carbonate, chloride, phosphate [P], or sulfate) to convert native Pb species to PLJ and used a mouse assay to assess relative bioavailability (RBA) of Pb in untreated (U) and remediated soils. Bone and blood Pb levels were significantly lower (P < 0.001, Student's t test) in mice that consumed diets amended with remediated soils than with U soils. Estimated RBA for Pb in both remediated natural soils and Pb-mineral spiked soils were reduced by >90% relative to Pb RBA for U soils, which is substantially more effective than other soil amendments, including P. X-ray absorption spectroscopy showed that >90% of all Pb species in remediated soils were converted to PLJ, and ingested PLJ was not chemically transformed during gastrointestinal tract transit. Post treatment neutralization of soil pH did not affect PLJ stability, indicating the feasibility in field conditions. These results suggest that formation of PLJ in contaminated soils can reduce the RBA of Pb and minimize this medium’s role as a source of Pb exposure for young children.

Plumbojarosite Remediation of Soil Affects Lead Speciation and Elemental Interactions in Soil and in Mice Tissues

“…For either treated soil, the Pb RBA was <1%. Reduced Pb bioavailability of both treated BHK soils was consistent with recent work that found treatment to promote PLJ formation decreased Pb bioavailability in another set of test soils . Notably, results of the current study and earlier work cited here show that the formation of PLJ significantly decreases Pb bioavailability .…”

“…Reduced Pb bioavailability of both treated BHK soils was consistent with recent work that found treatment to promote PLJ formation decreased Pb bioavailability in another set of test soils . Notably, results of the current study and earlier work cited here show that the formation of PLJ significantly decreases Pb bioavailability . By contrast, remediation of soils with phosphate had much more modest effects on Pb bioavailability in the mouse model. , These findings suggested that PLJ formation may be a superior method for remediation of Pb-contaminated soils, if scalable to field applications.…”

“…In situ conversion of Pb in soils into less bioavailable forms may be a cost-effective strategy to reduce Pb exposure from contaminated soils. ,− These remediation strategies decrease soil Pb bioavailability by changing the physical and chemical properties of Pb present in soil. For example, phosphate amendment of Pb-contaminated soils has been shown to convert soluble Pb species in soil into less soluble and less bioavailable Pb-phosphate species. , A novel method for the remediation of Pb-contaminated soil involving the promotion of plumbojarosite (PLJ) precipitation has recently been identified as a remediation methodology with the potential to significantly reduce bioaccessibility and bioavailability compared to existing methodologies . Plumbojarosite is a Pb-containing hydroxysulfate mineralPb 0.5 2+ Fe 3 3+ (OH) 6 (SO 4 ) 2 that is highly stable under acidic pH (<4) conditions. − Slow addition of a ferric sulfate-0.01 M H 2 SO 4 solution to a heated soil resulted in either complete or predominant (>90%) conversion of Pb species present to PLJ for all Pb standards and soils evaluated .…”

“…The bioavailability of the PLJ-treated soil has been assessed using a mouse model. The formation of PLJ markedly decreased RBA for Pb with RBA in treated soils <10% . Although PLJ formation may be an efficient and cost-effective alternative to current methods for soil Pb remediation, additional studies are needed to extend the findings of recently published research and facilitate modification that allow for field application.…”

Fluorescence ‘off–on’ probe for lead (II) detection based on Atractylodes III CQDs and bioimaging

“…Pb(II) is hard to migrate and degrade, which have become an important cause of Pb(II) pollution in soil, water, air, and many other places. [5][6][7][8][9][10][11][12][13] Lead (II) exists in the environment will eventually be transmitted to plants and the human body through the food chain, [14][15][16][17][18][19] causing damage to organs [20] and hormone levels. [21] For children, a very small amount of Pb(II) may inhibit their brain development, [22] break their bones, [23] even damage their DNA.…”