Sources of soil heavy metals and health risk assessment of crops in arable land at the periphery of a typical mercury mining area
This study aims to systematically assess the pollution risk of heavy metals in the soil-crop-human body system along the pe-riphery of mining areas,thus providing a scientific basis for the classified management of ecological risks and safe crop production in mining areas.Hence,this study examined the soil and crops(rice,corn,and sweet potato)in arable land along the periphery of a typical mercury mining area in Chongqing City.The single-factor pollution index(Pi),Nemero composite index(P综),and positive matrix factorization(PMF)model were employed to assess the pollution degree and ecological risk of soil heavy metals for source analy-sis.Moreover,the human health risk assessment model recommended by the United States Environmental Protection Agency(USEPA)was applied to assess the health risks of local staple crops for residents.The results are as follows:(1)The average contents of As,Cd,Cr,Cu,Hg,Ni,Pb,and Zn in the soil of the study area were all higher than the topsoil background values of Chongqing and China,suggesting that heavy metals are relatively enriched in topsoil;(2)The single-factor pollution index indicates that the over-limit ratios of Hg and Cd in the soil reached 96.29%and 92.59%,respectively,whereas rice,corn,and sweet potato samples with Cd con-tent exceeding the value specified in the national food safety standard(GB 2762-2022)accounted for 16.67%,18.75%,and 14.28%,respectively;(3)The Nemero composite index(P综)was between 1.17 and 46.05,suggesting mild to heavy pollution in the study area,with heavy pollution primarily located around the mercury mining area and artisanal mercury smelters,as well as the lower reaches of the Rongxi River;(4)The PMF model analysis demonstrates that the heavy metals in the soil of the study area origi-nate from three sources:natural source(47.21%),mining activities(16.00%),and a mixed source of mining and agricultural activ-ities(36.79%).Specifically,Cd,Cr,and Ni are principally affected by the natural source,Hg by mining activities,As and Pb by the mixed source of mining and agricultural activities,and Cu and Zn are associated with the natural source and the mixed source of mining and agricultural activities;(5)The human health risk model reveals that the consumption of rice,corn,and sweet potato poses composite health risks for both adults and children.Rice consumption exhibits the highest risk index,especially in children,with the main risk factors being As and Cd.
国家科技期刊平台
NSTL
万方数据
