Overview
This study developed and tested a soil remediation method that converts soil lead and arsenic into jarosite-group minerals — plumbojarosite (PLJ) and beudantite — which have exceptionally low bioaccessibility at gastric pH (1.5–3). Treatment with potassium jarosite seeding reduced Pb and As bioaccessibility from approximately 70% and 60% (unamended) to less than 10% across all treatment conditions, representing a rare dual remediation option addressing both metals simultaneously. This is particularly significant because conventional phosphate-based Pb remediation can actually increase As bioaccessibility through competitive sorption effects.
Key numbers
- Unamended soil Pb bioaccessibility: approximately 70%
- Unamended soil As bioaccessibility: approximately 60%
- Post-treatment Pb bioaccessibility: < 10% across all K-jarosite treatments
- Post-treatment As bioaccessibility: < 10% across all K-jarosite treatments
- HPb-HAs soil: 2,393 mg Pb/kg, 369 mg As/kg (legacy Pb arsenate pesticide, orchard)
- MPb-LAs soil: 746 mg Pb/kg, 6 mg As/kg (zinc smelter contamination, residential)
- PLJ conversion at 40 °C for HPb-HAs: 71 ± 3.2%
- PLJ conversion at room temperature (22 °C) for MPb-LAs: 81 ± 2.1%
- Additional soils (200–500 mg Pb/kg): PLJ conversion ≥ 85% at room temperature
- US EPA soil Pb screening levels: 400 mg/kg (play areas), 1,200 mg/kg (other residential)
Bioaccessibility measured by EPA Method 1340 (glycine extraction at pH 1.5, 37 °C, 1 hour). Pb and As quantified by ICP-MS (iCAP RQ). Pb speciation by X-ray absorption near-edge structure (XANES) linear combination fitting.
Methods (brief)
Laboratory potted-soil experiments. K-jarosite synthesized per Baron and Palmer. Soils treated at various temperatures (room temperature, 40, 50, 60 °C) with and without K-jarosite seeding. 16-hour reaction time. Pb bioaccessibility by EPA Method 1340 (in vitro bioaccessibility assay). Pb and As speciation by bulk Pb L-III edge and As K-edge XAS at Argonne National Laboratory (MRCAT beamlines 10-ID and 10-BM). Fe⁵⁷ Mossbauer spectroscopy for jarosite-phase confirmation. NIST SRM 2710a (Montana I Soil) for method validation.
Implications
Certification: This is a supply-chain remediation paper, not a food-matrix measurement paper. It is relevant to the mitigation framework: when crops are grown in Pb/As-contaminated soil (legacy orchards, industrial sites, urban gardens), jarosite treatment is a potential in situ agronomic lever that can reduce dietary exposure via soil-to-plant transfer pathways. The bioaccessibility reduction from ~65% to < 10% is a meaningful magnitude for risk-reduction arguments.
Courses: Good case study for the interaction between Pb and As remediation — the conventional phosphate approach to Pb remediation worsens As exposure. The dual-remediation jarosite approach resolves this tradeoff.
App: Not directly applicable to ingredient-level contamination profiles, but informs the supply-chain screening module for legacy-orchard or smelter-adjacent agricultural sourcing.
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 6 sections added; narrative text revised |