东莞市土壤重金属富集特征及其环境风险研究OA

To evaluate the pollution characteristics and combined risks of soil heavy metals under different land use types in Dongguan City,this study systematically collected 9 852 surface soil samples(including 7 299 from construction land and 2 553 from agricultural land)across the city.The concentrations of eight heavy metals were determined.By integrating the geo-accumulation index,potential ecological risk index,and human health risk assessment models,differences in pollution levels and associated risks between the two land use types were compared and analyzed.The results indicated that the overall heavy metal content in the study area was relatively low,but its spatial distribution was significantly influenced by land use.In construction land,Pb,Cu,and Zn were locally enriched in industrial and residential areas.For agricultural land,Cd content generally exceeded the background value for Guangdong Province,with a high coefficient of variation reaching 542.47%,indicating strong spatial heterogeneity.The geo-accumulation index suggested that the soil was generally uncontaminated overall,with only isolated points of light to moderate pollution by Cd,Pb,and Zn found in construction land.Regarding potential ecological risk,agricultural land was primarily at low risk,with Cd and Hg being the main contributing factors,while localized areas showed moderate to high risk.Health risk assessment revealed that the total carcinogenic risk for both adults(TCR 2.20×10−5to 2.38×10−5)and children(TCR 4.53×10−5to 4.88×10−5)falled within the acceptable range,although the risk for children approached the upper threshold.Cr and As were identified as the primary contributing factors,with hand-to-mouth ingestion being the dominant exposure pathway.This study could provide a scientific basis for the classified management,risk zoning,and development of prevention and control strategies for soil heavy metals in Dongguan City.