Abstract: Heavy metals have caused varying degrees of soil pollution in municipal solid waste (MSW) landfills. To better investigate, assess, and remediate heavy metal pollution in landfill soils, this study took sanitary MSW landfills, simple landfills, temporary dumping sites, and waste transfer stations as research objects. Methods including the Nemerow Pollution Index method (PI), Potential Ecological Risk Index method (RI), Risk Assessment Code method (RAC), and mathematical statistics were adopted, to analyze the pollution status, speciation, and influencing factors of heavy metals (Fe, Mn, Pb, Cd, Cu, Hg) in the soils. The results showed that cadmium (Cd, PI = 0.57-2.61) and mercury (Hg, PI = 0.62-2.70) were the main heavy metal pollutants in the landfill soils, with 25.0%-83.3% and 33.3%-100.0% of the sampling sites exceeding the soil risk screening values, respectively. The heavy metals including Fe, Pb, Cd and Cu had a main form of residual state (33%-96%), and the Mn had a main form of Fe-Mn oxidation state (34%-65%)， the Risk Index (RI) values of different types of landfill sites ranged from 63.83 to 147.85. Therefore, the type of landfill site exerts a significant impact on the total content and speciation of heavy metals in soil. In the daily management of landfill sites, emphasis should be placed on the pollution prevention and control measures for MSW transfer stations (RI = 147.85), simple landfill sites (RI = 147.55), and temporary dumping site A (RI = 119.56).

Key words: waste dumps, heavy metals, form characteristics, soil contamination assessment, spatial distribution