Abstract: Chemical leaching is characterized by high efficiency, thorough rehabilitation, and reduction of contaminated soil. However, the cost of soil leaching is relatively high and the fine soil after chemical leaching needs to be solidified and stabilized, which limits the large-scale application of this technology. Cr(VI) contaminated fine soils were collected from Chongqing to explore the remediation effect and economic feasibility of chemical leaching. The results showed that, with increasing concentrations of oxalic acid, citric acid, acetic acid, and hydrochloric acid, the removal rate of Cr(VI) in soil increased gradually, with oxalic acid and citric acid having the best performance. The chemical leaching effect and stability were the best when the liquid-solid ratio was 5∶1-10∶1, which decreased when the liquidsolid ratio was greater than 10∶1 or lower than 5∶1. As processing time increased, the removal rate of Cr(VI) increased and the leaching concentration of Cr(VI) in soil decreased. Using oxalic acid and citric acid as mixed eluent, under the condition of liquidsolid ratio of 5∶1 and leaching for 45 min, the removal rate of Cr(VI) in soil was 62.73%, the leaching concentration of Cr(VI) was 0.64 mg·L^-1, being lower than 1.5 mg·L^-1 of the standard of Cr(VI) landfill. The cost of Cr(VI) contaminated fine soil leaching eluent was estimated as 300 CNY·t^-1 soil, with economic feasibility for engineering application.

Key words: genetic structure, genetic diversity, South China., Hemibarbus medius, Hemibarbus labeo, COI gene, ND5 gene