Current Status and Development of Remediation for Heavy Metals in China

At present, the problem of heavy metal pollution is a hot topic in the world. There are significant differences in the types and concentrations of metal ions distributed in each contaminated sites. In China, due to the vast territory and diverse ecoenvironments, the pollution situation is complex and variable, and the composite pollution is particularly obvious. Overall, pollution in the southern provinces is relatively higher than in other provinces, and Cd, Hg, Pb, Cr, As and Ni are listed as the priority pollutants for control. The metals have different physical or chemical specificity that allows them to be treated differently. Toxic Cr(VI) needs to be reduced to non-toxic Cr(III) before removal, whereas Cd(II) can form an insoluble Cd compound precipitate under alkaline conditions. Nevertheless, the characteristics of the soil itself such as pH, humidity, mineral composition, etc., are the hurdles in the process of remediation. Therefore, this review systematically summarizes the characteristics of heavy metal contaminated soil in major areas of China. It also proposes appropriate restoration methods and schemes such as phytoremediation and microbial remediation, which provides a theoretical basis for the elimination of heavy metals from a polluted land.