Environmental risk assessment and factors influencing heavy metal concentrations in the soil of municipal solid waste landfills

The environmental risk assessment and the factors influencing heavy metals (HM) in the soil at the municipal solid waste landfill sites (MSWLs) were studied by literature review, field survey, and statistical methods. The results indicated that the dominant HM contamination in the soil at the MSWLs was caused by chromium (Cr) with the Nemero index values (PI) from 22.7 to 44.3 and zinc (Zn) with the PI from 0.7 to 9.8. There were significant differences in the Cr, mercury (Hg), lead (Pb), Zn, and arsenic (As) concentrations between soil samples from sanitary and non-sanitary landfills (NSLs) where HM contamination (PI = 10.9) was more obvious. As (CRAAs = 2.35 × 10-4) and cadmium (Cd) (CRACd = 1.45 × 10-4) posed potential carcinogenic health effects. The soil Cd concentration had a significant negative correlation (r = -0.476**) with the landfill age. The soil As concentration had a significant positive correlation (r = 0.472**) with rainfall in NSLs. There were significant differences in the As (P = 0.042) and copper (Cu) (P = 0.042) concentrations between soil samples from the surrounding areas of MSWLs and the base where soil had higher HM concentrations. For the efficient prevention of HM ecological risk, a scientific site selection, undamaged coverage and anti-seepage systems, standardized management, and ongoing monitoring are required.