| Cultivated land is one of the most important natural resources on the earth.It is an important basic material and resource for human survival and development.In order to study the current status of potentially toxic elements in the surface soil of the cultivated land in Xiangzhou,Xiangyang City,Hubei Province,and the spatial distribution characteristics and sources of potential toxic elements in the soil,975 surface soil(0～5 cm)samples were collected in 2019 and the cadmium was determined.(Cd),mercury(Hg),arsenic(As),lead(Pb)and chromium(Cr)5 potentially toxic elements(unit:mg·kg-1),and the potential toxic element content of the soil at the sample point The statistical values are used in ArcGIS 10.2 software to perform inverse distance weight interpolation(IDW)to obtain the spatial distribution of potential toxic elements in the soil in Xiangzhou.Human health risk assessment and ecological risk assessment methods are used to determine the risk level of the study area,and comprehensive application of multiple Statistical analysis and random forest regression model are used to quantitatively analyze the influencing factors of potential toxic elements,and further explore the sources of potential toxic elements in soil.Studies have shown that the comprehensive application of multiple technologies is a more scientific and accurate method to study the sources of potential toxic elements in the soil.The results showed that:(1)The average content of potentially toxic elements in the soil of the farmland sample points in Xiangzhou was 0.14 mg/kg(Cd),0.05 mg/kg(Hg),12.33 mg/kg(As),28.39 mg/kg(Pb)and 75.21 mg/kg(Cr).The content of As and Pb exceeds the background value of Hubei soil.The average content of Hg,Cd,and Cr is lower than the soil background value in Hubei Province;the average content of As is slightly higher than the background value;the average value of Pb exceeds the background value,and the maximum value is 47.1 mg·kg-1,which is the background value 1.76 times of Pb,indicating that Pb has been enriched.(2)The human health risk assessment in the study area shows that the most important source of potentially toxic elements is through food intake,accounting for 99%of the total risk sources.The non-carcinogenic risk of As,Pb and Cr in soil is higher than the limit for children and adults(HI>1).In addition,the carcinogenic risks of Cd,Cr,and As to children and adults are all higher than the limit(10-4),which indicates that Cd,As,Pb,and Cr in the soil of the study area pose a greater threat to human health.(3)The ecological risk assessment results show that there is no Cr pollution(low pollution)in the cultivated soil of the study area.However,the ecological risks of As and Pb still exist,and the spatial difference is obvious.The pollution of Cd and Hg is relatively serious,which poses a certain threat to environmental health.(4)Suspected water pollution sources are the main factors affecting the content of Cd,Hg,As and Pb,and suspected soil and air pollution sources are the common source of five potentially toxic elements.In agricultural breeding,for example,livestock manure is used as farmyard manure in cultivated land,which is an important factor affecting Hg and Cr content.Mining activities have a greater contribution to the Cr content in the surrounding soil. |
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