Abstract Soil organic carbon (SOC) is a crucial component that significantly affects the soil fertility, soil remediation, and carbon sequestration. Here, we review the redox-induced transformation of potentially toxic elements (PTEs) through the abiotic impact of SOC. The complex composition of SOC includes humus, pyrogenic carbon (e.g., biochar), dissolved organic matter, and anthropogenic carbon (e.g., compost), with varying concentrations and properties. The primary redox moieties on organic carbon are surface functionalities (e.g., phenol, quinone, and N/S-containing functional groups), environmentally persistent free radicals, and graphitic structures, and their contents are highly variable. Owing to these rich redox moieties, organic carbon can directly affect the reduction and oxidation of PTEs in the soil, such as Cr(VI) reduction and As(III) oxidation. In addition, the interactions between organic carbon and soil redox moieties (i.e., O 2 , Fe, and Mn minerals) cause the transformation of PTEs. The formation of reactive oxygen species, Fe(II), and Mn(III)/Mn(II) is the main contributor to the redox-induced transformation of PTEs, including Cr(VI) reduction and As(III)/Cr(III)/Tl(I) oxidation. We articulated both the positive and negative effects of organic carbon on the redox-induced transformation of PTEs, which could guide soil remediation efforts. Further scientific studies are necessary to better understand the potential transformations of PTEs by SOC, considering the complicated soil moieties, variable organic carbon composition, and both biotic and abiotic transformations of PTEs in the environment. Graphical Abstract 

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Redox-induced transformation of potentially toxic elements with organic carbon in soil

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Papers

Chromium biogeochemical behaviour in soil-plant systems and remediation strategies: A critical review.

Natural source of Cr(VI) in soil: The anoxic oxidation of Cr(III) by Mn oxides.

Enrichment and speciation of chromium during basalt weathering: Insights from variably weathered profiles in the Leizhou Peninsula, South China.

Increasing soil Mn abundance promotes the dissolution and oxidation of Cr(III) and increases the accumulation of Cr in rice grains.

Nano Zero-Valent Iron Enhances the Mobilization and Absorption of Chromium in Rice (Oryza Sativa L.): Implication for Cr Risks Management in Paddy Fields