Progress in the study of influencing factors and action mechanism of chromium valence transformation in soil.
BAO Chenglong, LIU Genhong*
Soil chromium (Cr) contamination has become a global challenge in environmental remediation owing to its high environmental toxicity and cyclic complexity. The environmental toxicity and risk of chromium mainly depend on its chemical valence. The hexavalent chromium (Cr(VI)) being highly toxic and dispersible, whereas trivalent chromium (Cr(III)) is less toxic and more easily precipitated. Therefore, revealing the processes and mechanisms of chromium valence transformation in soil is key to assess its environmental risk and develop remediation technologies. In this study, we systematically reviewed global research on different valence transformation mechanisms of chromium, with a focus on the key drivers, including pH, redox potential (Eh), organic matter, microorganisms, Fe-Mn oxides, and other environmental factors. Three types of dominant transformation mechanisms were identified, including the chemical redox mechanism primarily occurring in the Fe-Mn cycle, the synergistic adsorption-reduction-complexation processes of organic matter, and the enzymatic and non-enzymatic reduction pathways involving microorganisms. Currently, there is a knowledge gap in multifactorial coupling, micro-interfacial processes, and environmental effects of complexes. Future research should combine analyses of multifactorial effects, microbial chromium transformation mechanisms based on macrogenomics and proteomics, and synchrotron radiation to comprehensively explore chromium valence transformation behavior under the influence of multifactorial coupling and in microenvironments.
BAO Chenglong, LIU Genhong. Progress in the study of influencing factors and action mechanism of chromium valence transformation in soil.[J]. Chinese Journal of Ecology, 2026, 45(7): 2177-2184.
