Distribution Characteristics, Pollution Assessment, and Source Identification of Heavy Metals in Soils Around a Landfill-Farmland Multisource Hybrid District

Heavy-metal pollution is a negative impact of municipal solid-waste landfills. The multiple pollution transport pathways (including leachate, runoff, and waste gas) and complex and co-existing potential pollution sources (such as agricultural activities) around landfills require a combination of different pollution assessment methods and source identification tools to address pollution distribution and potential risks. In this study, the distributions of eight heavy metals (chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), cadmium (Cd), and mercury (Hg)) around a landfill were analyzed using 60 topsoil samples. Ecological risk assessments indicated that there are currently no ecological risks. Based on health risk assessments, however, high concentrations of Cr and As in the soil pose a noncarcinogenic and carcinogenic risk to humans in the study area, respectively. In addition, the geoaccumulation indices for Cr, Cu, Ni, Zn, As, and Hg confirmed anthropogenic sources of accumulation of these metals in soils. Additionally, the potential ecological risk index indicated that Hg posed a considerable risk to the ecology of the area around the landfill. Sources of heavy metals in the study area were attributed to natural sources (22.10%), agricultural activities (27.65%), landfill (31.35%), and transportation (18.89%). The continuous accumulation of heavy metals and health risk for humans suggests the need to continuously monitor of heavy metal content and migration around the landfill. This study provides a reference for local authorities in the study area.