A Review of Chromium Behavior in Soil and its Remediation Techniques

The contamination of soil by potentially toxic elements has attracted global attention. Soil pollution caused by Cr, one of the toxic elements, poses a great threat to human health and ecosystem security. In order to clarify the flow direction of Cr pollutants and achieve accurate restoration of soil Cr pollution, it is very important to analyze the whole life cycle from pollution source to extinction. Therefore, this work analyzed the source of soil Cr pollutants, the migration and transformation behavior of Cr after entering the soil under the action of hydraulics, soil and microorganisms to clarify its flow and enrichment patterns. The biogeochemical and anthropogenic effects on Cr distribution and its biotoxicity were analyzed. Finally, recent advanced restoration techniques and future challenges were assessed. Improper disposal of all Cr-containing wastes will lead to soil pollution. The migration capacity of Cr(VI) was higher than that of Cr(III) and was affected by soil properties. Cr undergoes a continuous redox cycle between soil, microorganisms, and the atmosphere. Almost all Cr(VI) compounds are biotoxic. Serious Cr pollution areas were distributed around human production and living areas. In the future, in situ bioremediation based on genetically engineered bacteria and hyperaccumulator plants with high-biomass is the cleanest, efficient, and safe alternative.