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

Zibo Xu, Daniel C.W. Tsang

Research output: Journal article publicationReview articleAcademic researchpeer-review

51 Citations (Scopus)


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., O2, 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: [Figure not available: see fulltext.]

Original languageEnglish
Article number9
JournalCarbon Research
Issue number1
Publication statusPublished - Dec 2022


  • Biochar
  • Electron transfer
  • Redox reaction
  • Soil carbon
  • Soil remediation
  • Trace elements

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Engineering (miscellaneous)
  • Environmental Science (miscellaneous)


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