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<p>Zerovalent iron (Fe)-doped biochar (BC/ZVI) is an efficient and sustainable approach for remediating chromium (Cr)-polluted soils. However, the effects of different exogenous organic materials on performance of BC/ZVI in Cr-immobilization from contaminated soils remained poorly understood. Here, BC vs BC/ZVI (2%) was added to the Cr-spiked soil (500&#xa0;mg kg<sup>− 1</sup>) supplemented by composted (chicken manure, CMOF) and uncomposted (wheat straw, SOF) organic materials (1%) under controlled conditions to explore respective potentials for Cr immobilization, Fe dynamics and microbial communities behavior. The results of soil incubation experiment demonstrated that supplementation of organic materials to BC and BC/ZVI exhibited significant (<i>p</i> &lt; 0.05) effects in altering soil physicochemical attributes (pH, EC and DOC contents), Cr availability, and microbial communities. Compared to BC/ZVI treatments, SOF + BC/ZVI significantly reduced available Cr fraction by 65%, but CMOF + BC/ZVI showed no significant effects on bioavailable Cr. Fe species analysis revealed that incorporation of SOF and CMOF with BC/ZVI increased Fe<sup>2+</sup> and Fe<sup>3+</sup> concentrations significantly in the soil. <i>Bacillus</i> and <i>TM7a</i> population were abundant in BC/ZVI and with addition of CMOF whereas <i>Ensifer</i> genera was in higher proportion with BC and BC + SOF treatments. This work highlighted the significance of OM sources integration to BC vs. BC/ZVI for developing insight towards sustainable Cr-contaminated soil remediation techniques by altering soil physicochemical, Fe species/oxides and microbial attributes.</p> Graphical Abstract <p>The graphical abstract in this study represents the importance of straw (uncomposted) (SOF) and composted chicken manure organic fertilizer (CMOF) as amendments to biochar (BC) and zerovalent iron (Fe)-doped biochar (BC/ZVI) on soil physicochemical properties, microbial community dynamics, and chromium (Cr) immobilization. Through a controlled incubation experiment, we demonstrate that the source of organic materials (plants origin and avian (biogenic)) significantly influences Cr bioavailability and redox transformation. Incorporation of SOF and CMOF regulated the Fe species transformation and its associated oxides in terms of amorphous Fe, crystalline Fe and complex state Fe oxides. Enriched Cr reducing bacteria played an integral role on regulating Cr transformation and its immobilization. These findings underscore the importance of OM source and quality (composting status) in Cr remediation, offering sustainable insights for Cr mitigation in agroecosystems.</p>

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Role of Exogenous Organic Materials in Enhancing BC/ZVI-mediated Chromium Immobilization Via Microbial and Geochemical Transformation

  • 期刊论文

  • 发表日期：

    2025年9月9日

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  • Tang Yuan,
  • Siyu Wei,
  • Wan Yang,
  • Shengsen Wang,
  • Muhammad Mahroz Hussain

摘要

Zerovalent iron (Fe)-doped biochar (BC/ZVI) is an efficient and sustainable approach for remediating chromium (Cr)-polluted soils. However, the effects of different exogenous organic materials on performance of BC/ZVI in Cr-immobilization from contaminated soils remained poorly understood. Here, BC vs BC/ZVI (2%) was added to the Cr-spiked soil (500 mg kg− 1) supplemented by composted (chicken manure, CMOF) and uncomposted (wheat straw, SOF) organic materials (1%) under controlled conditions to explore respective potentials for Cr immobilization, Fe dynamics and microbial communities behavior. The results of soil incubation experiment demonstrated that supplementation of organic materials to BC and BC/ZVI exhibited significant (p < 0.05) effects in altering soil physicochemical attributes (pH, EC and DOC contents), Cr availability, and microbial communities. Compared to BC/ZVI treatments, SOF + BC/ZVI significantly reduced available Cr fraction by 65%, but CMOF + BC/ZVI showed no significant effects on bioavailable Cr. Fe species analysis revealed that incorporation of SOF and CMOF with BC/ZVI increased Fe2+ and Fe3+ concentrations significantly in the soil. Bacillus and TM7a population were abundant in BC/ZVI and with addition of CMOF whereas Ensifer genera was in higher proportion with BC and BC + SOF treatments. This work highlighted the significance of OM sources integration to BC vs. BC/ZVI for developing insight towards sustainable Cr-contaminated soil remediation techniques by altering soil physicochemical, Fe species/oxides and microbial attributes.

Graphical Abstract

The graphical abstract in this study represents the importance of straw (uncomposted) (SOF) and composted chicken manure organic fertilizer (CMOF) as amendments to biochar (BC) and zerovalent iron (Fe)-doped biochar (BC/ZVI) on soil physicochemical properties, microbial community dynamics, and chromium (Cr) immobilization. Through a controlled incubation experiment, we demonstrate that the source of organic materials (plants origin and avian (biogenic)) significantly influences Cr bioavailability and redox transformation. Incorporation of SOF and CMOF regulated the Fe species transformation and its associated oxides in terms of amorphous Fe, crystalline Fe and complex state Fe oxides. Enriched Cr reducing bacteria played an integral role on regulating Cr transformation and its immobilization. These findings underscore the importance of OM source and quality (composting status) in Cr remediation, offering sustainable insights for Cr mitigation in agroecosystems.