Heavy metal pollution in the soil of contaminated sites in China: Research status and pollution assessment over the past two decades

Contaminated sites are receiving more and more attention internationally because they pose a serious threat to the ecological environment and human health. Although the research focused on heavy metals pollution in the soil of contaminated sites has been rapidly developing over the past two decades, systematic research status analysis and pollution assessment are still lacking. Here, through the "front page filtering " script and successive screening of the relevant studies, the research status of heavy metal pollution in the soil of contaminated sites worldwide and especially in China had been synthetically analyzed. The result showed that China and USA were the most active countries in related research, and the main research subjects were the assessment of contaminated sites and remediation methods. The keyword co-occurrence network of heavy metal contaminated sites in China was divided into three clusters, focusing on different environmental media, physical-chemical remediation and phytoremediation technologies. The types of contaminated sites in China mainly included mining areas (the largest proportion), industrial zones, sewage irrigation, and dismantling sites, etc. Cd and Pb were the most widely studied heavy metal in China. The pollution of heavy metals in the soils of contaminated sites was ranked as: Cd > Pb > Cu/Zn/Hg > As/Cr > Ni, and it was more serious in southeast China than northwestern China.