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Biochar-impacted sulfur cycling affects methylmercury phytoavailability in soils under different redox conditions.
- Source :
-
Journal of hazardous materials [J Hazard Mater] 2021 Apr 05; Vol. 407, pp. 124397. Date of Electronic Publication: 2020 Oct 29. - Publication Year :
- 2021
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Abstract
- Recently, there has been increasing interest in reducing methylmercury (MeHg) phytoavailability using biochar, although the underlying mechanisms are not fully understood. By combining lab-scale batch incubation with pot and field validations, we demonstrate that biochar-impacted sulfur cycling in soils and MeHg-soil binding play key roles in controlling MeHg phytoavailability. (1) Under anoxic conditions, biochar-associated sulfate and biochar-facilitated microbial sulfate reduction enhanced the production of reduced inorganic sulfur species as acid-volatile sulfide (AVS) in soils by 122%, facilitating MeHg binding with soils and thus reducing MeHg phytoavailability. (2) In contrast, under oxic conditions, the reduced inorganic sulfur was oxidized (resulting in a 68-91% decrease in AVS), which released soil-bound MeHg and increased MeHg phytoavailability. The proposed mechanisms could explain the distinct effects of biochar amendment on MeHg bioaccumulation observed under anoxic (10-88% lower in rice grains) and oxic conditions (48-84% higher in wheat grains). Our results dispute the commonly held assumption that reduced MeHg phytoavailability under biochar amendment can be primarily attributed to MeHg-biochar binding. Therefore, the potential increased risk of MeHg in oxic soils following biochar amendment should be evaluated in more detail.<br /> (Copyright © 2020 Elsevier B.V. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1873-3336
- Volume :
- 407
- Database :
- MEDLINE
- Journal :
- Journal of hazardous materials
- Publication Type :
- Academic Journal
- Accession number :
- 33183839
- Full Text :
- https://doi.org/10.1016/j.jhazmat.2020.124397