Research Progress on Influencing Factors and Mechanisms of Chromium Valence State Transformation in Soil

Chromium (Cr) pollution in soil is a global environmental problem, and hexavalent chromium Cr(Ⅵ) has become a focus of attention due to its high toxicity and carcinogenicity. Cr in soil mainly exists in the form of Cr(Ⅲ) and Cr(Ⅵ), and the transformation between the two is influenced by factors such as soil pH, redox potential (Eh), natural redox agents, organic matter, and microorganisms. This article provides an overview of the global pollution status and sources of Cr in soil, as well as the different valence states and toxicity characteristics of Cr in soil. It also analyzes the redox mechanisms of chromium valence state transformation in soil affected by different factors, as well as the interactions between different factors. In addition, through a deep understanding of the factors affecting the valence state of Cr, advanced remediation techniques represented by biochar and nanomaterials have emerged. These methods can effectively reduce Cr(Ⅵ) to less toxic Cr(Ⅲ), thereby reducing ecological and environmental risks. Therefore, they are a potentially valuable remediation material and technique. However, the feasibility and effectiveness of large-scale applications still need further verification. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202401180007.