Soil pollution is an environmental hot spot of public concerns.The quality of the soil environment will affect the quality of cultivated land,the safety of agricultural products,and human health.At present,due to a series of problems,the existing survey results are difficult to support the needs of work at this stage.This study takes three agricultural land in Xuzhou City.The method combines outdoor survey and sampling,indoor experiments,data analysis,and numerical simulation.To carry out research on the impact of external pollution on the distribution of heavy metals in agricultural land in Xuzhou and its risk assessment.The conclusion as below:(1)The accumulation degree of soil heavy metals(Cr,Ni,Cu,Cd,Pb)in the study area is different,Cd has exceeded the standard in all regions.The content of heavy metals in the soil is different at different depths.The average content of Cr,Ni,Cu,Pb in the surface layer is greater than that at the depth of 60 cm.(2)The accumulation of heavy metal content in the soil is related to the surrounding pollution sources,human production activities,traffic and other factors.The order of the average content of Cr and Ni is Y area,H area and L area.The order of the average content of Cu and Pb is H area,Y area and L area.The order of the average content of Cd is H area,L area and Y area.The correlation coefficients of Cr-Ni(0.864),Cr-Cd(0.658),Ni-Cd(0.655),and Cd-Pb(0.536)are relatively more significant,indicating that they may have a homologous pollution relationship.(3)The average value of the individual pollution index of Cd in the study area is 1.9476,and it is slightly polluted.The other four heavy metals are not polluted.The average value of Nemerow index is 1.4901,which is light pollution.soil pollution presents a warning-lightmoderate pollution level.(4)There are three ecological risk levels: low,medium and high in the study area,the Cd has the greatest degree of potential harm.(5)The non-carcinogenic risk of several heavy metals in the study area is in the order of Cr,Ni,Cd,Cu.Oral intake is the main source of non-carcinogenic risk of Cu.Inhalation of soil particulate matter is the main contributor of Cr,Ni,and Cd.Oral ingestion and inhalation of soil particles are the main carcinogenic exposure routes.(6)As the depth of soil layer increases,the migration rate and concentration of heavy metals decreases. |