Abstract: To investigate the pollution characteristics,sources,and human health risks of heavy metals in a typical lead zinc smelter,this study targeted an abandoned lead-zinc smelter in Gansu Province.A total of 39 topsoil samples were systemat ically collected,and the concentrations of seven heavy metals—arsenic (As),cadmium (Cd),copper (Cu),lead (Pb),mer cury (Hg),nickel (Ni),and zinc (Zn)—were determined.Comprehensive assessments,including geostatistics,the single fac tor index method,the Nemerow comprehensive pollution index method,the potential ecological risk index (PERI) method,the Positive Matrix Factorization (PMF) model,and the human health risk assessment model,were employed to evaluate the spa tial distribution,pollution level,ecological risk,source apportionment,and health risks of soil heavy metals.The results indica ted that the soil in the study area was alkaline.With the exception of Ni,the average concentrations of all other heavy metals significantly exceeded the background values for Gansu soils,with As,Cd,Hg,and Zn showing the highest enrichment factors at 13.15,25.28,71.52,and 11.03 times the background values,respectively.Spatially,the high-value areas for As,Cd,Pb,and Zn were concentrated in the wastewater treatment area and the production workshop.Pollution evaluation revealed that As was at a slight pollution level based on the single factor index,and the Nemerow index indicated that the overall study area was at a slight pollution level.However,the potential ecological risk index suggested a very high ecological risk,primarily contributed by Hg,Cd,and As.The PMF model identified three main sources:smelting pollution source (contributing 52.19%),dust fall source (contributing 22.78%),and natural source (contributing 21.99%).Health risk assessment showed that the non-carci nogenic risk for adults was close to the threshold,while the total carcinogenic risk exceeded the acceptable level,indicating an unacceptable carcinogenic risk.Arsenic (As) was the primary carcinogenic factor,and oral ingestion was the main exposure pathway.This study provides a critical scientific basis for soil pollution risk control and remediation at the smelter site.

Key words: lead-zinc smelter,soil heavy metals,spatial distribution,source apportionment,health risk assessment