In this study, a collaborative system of Fe⁰ and mixed anaerobic microorganisms was established for remediating chromium (Cr)-contaminated soil and restraining the translocation of Cr from soil to swamp cabbage (Ipomoea aquatica Forssk.). Solid phase characterization demonstrated that more reactive secondary minerals such as green rust, magnetite, and lepidocrocite were generated in the composite system as compared with the Fe⁰-only system. Hence, the Fe⁰–microorganisms composite system achieved a remarkably higher aqueous Cr(VI) removal of 85.6%, 2.9 times higher than that in the Fe⁰-only system. After 14 d remediation, easily available Cr(VI) and Cr_total species such as water-soluble, exchangeable, and bound-to-carbonates were converted to less available Cr(III) and Cr_total species (e.g., Fe–Mn oxides-bound and organic matter-bound species) because of the production of Cr–Fe hydroxides and oxides [Cr_xFe_1−x(OH)₃ or Cr_xFe_1−xOOH] on the Fe⁰ surface. A pot experiment showed that Cr uptake by swamp cabbage after the composite system remediation was suppressed by 69.1%, two times higher than that after the Fe⁰-only system remediation. Excessive Fe uptake by swamp cabbage also was efficiently inhibited by the composite system treatment due to enhanced Fe hydroxides and oxides production on the Fe⁰ surface because of biological corrosion and mineralization. These results indicated that Fe⁰–microorganisms composite system remediation could efficiently enhance Cr(VI) immobilization and decrease its bioavailability and bioaccumulation by plants, which is a promising technology in Cr-contaminated soil remediation.

中文翻译：

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Fe0-微生物复合系统对 Cr(VI) 的增强固定：基准和盆栽实验

在这项研究中，建立了 Fe ⁰和混合厌氧微生物的协同系统，用于修复铬 (Cr) 污染的土壤并抑制 Cr 从土壤向沼泽白菜 ( Ipomoea Aquatica Forssk.)的易位。固相表征表明，与仅含 Fe ^{0 的}系统相比，在复合系统中生成了更多反应性次生矿物，如绿锈、磁铁矿和纤铁矿。因此，Fe ^{0 -}微生物复合系统实现了显着更高的 85.6% 的水性 Cr(VI) 去除率，是仅Fe ⁰系统的2.9 倍。修复14 d后，易获得的Cr(VI)和Cr_总量由于 Cr 的产生，水溶性的、可交换的和与碳酸盐结合的物种被转化为较少可用的 Cr(III) 和 Cr_总物种（例如，Fe-Mn 氧化物结合和有机物质结合的物种） -Fe ⁰表面上的Fe氢氧化物和氧化物[Cr _x Fe _1-x (OH) ₃或Cr _x Fe _1-x OOH] 。盆栽试验表明，复合系统修复后的沼泽白菜对Cr的吸收抑制了69.1%，是Fe ⁰- 仅系统修复。由于生物腐蚀和矿化，在 Fe ⁰表面增加了 Fe 氢氧化物和氧化物的产生，复合系统处理也有效地抑制了沼泽白菜对 Fe 的过度吸收。这些结果表明，Fe ^{0 -}微生物复合体系修复可以有效提高Cr(VI)的固定性，降低其生物有效性和植物对Cr(VI)的生物积累，是一种很有前景的Cr污染土壤修复技术。