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<p>Iron (Fe) oxides and natural organic matter (NOM) are ubiquitous and reactive components in various environmental systems, significantly influencing the fate and transport of contaminants. While Fe oxides typically sequester these contaminants, their reductive dissolution is a critical process that leads to remobilization, posing renewed environmental risks. This review synthesizes the current understanding of how NOM influences the reductive dissolution of Fe oxides. We summarize the mechanisms by which NOM drives this process: (1) acting as an electron donor and electron shuttle to accelerate reduction, (2) altering the morphology and size of Fe oxides, and (3) complexing with Fe(II) and Fe(III) to facilitate reduction. We further examine the biogeochemical dynamics of critical toxic oxyanions, specifically arsenic (As) and chromium (Cr), during the interaction of Fe oxides and NOM under reducing conditions. We highlight that NOM drives Fe oxide reduction and the concurrent reductive release of As, while directly reducing Cr, a process amplified by Fe oxides. Furthermore, NOM regulates the subsequent immobilization of As and Cr into secondary phases by retarding Fe oxide transformations. Together with competitive adsorption and complexation within the ternary system, these interconnected processes intricately control the biogeochemical cycling of As and Cr. Overall, this review provides a more profound understanding of Fe cycling and the associated fate of typical oxyanion contaminants in response to NOM, offering a theoretical basis for effective environmental remediation and management.</p> Graphical abstract <p></p>

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Effects of natural organic matter on iron oxide reduction and the subsequent impacts on oxyanion contaminant dynamics: a review

  • 期刊论文

  • 发表日期：

    2026年5月16日

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  • Yaqin Zhang,
  • Liuting Song,
  • Qiyuan Liu,
  • Zening Lv,
  • Tongying Yan,
  • Shunda Yuan

摘要

Iron (Fe) oxides and natural organic matter (NOM) are ubiquitous and reactive components in various environmental systems, significantly influencing the fate and transport of contaminants. While Fe oxides typically sequester these contaminants, their reductive dissolution is a critical process that leads to remobilization, posing renewed environmental risks. This review synthesizes the current understanding of how NOM influences the reductive dissolution of Fe oxides. We summarize the mechanisms by which NOM drives this process: (1) acting as an electron donor and electron shuttle to accelerate reduction, (2) altering the morphology and size of Fe oxides, and (3) complexing with Fe(II) and Fe(III) to facilitate reduction. We further examine the biogeochemical dynamics of critical toxic oxyanions, specifically arsenic (As) and chromium (Cr), during the interaction of Fe oxides and NOM under reducing conditions. We highlight that NOM drives Fe oxide reduction and the concurrent reductive release of As, while directly reducing Cr, a process amplified by Fe oxides. Furthermore, NOM regulates the subsequent immobilization of As and Cr into secondary phases by retarding Fe oxide transformations. Together with competitive adsorption and complexation within the ternary system, these interconnected processes intricately control the biogeochemical cycling of As and Cr. Overall, this review provides a more profound understanding of Fe cycling and the associated fate of typical oxyanion contaminants in response to NOM, offering a theoretical basis for effective environmental remediation and management.

Graphical abstract