| Mineral mining causes the surrounding farmland soil environment to be seriously polluted by heavy metals,and further pollutes crops and harms to human health.In order to find out the pollution situation and health risk of farmland soil and crops around a mining area in Hunan,the content of heavy metals in farmland and crops in a mining area in Hunan was determined.The pollution status of heavy metals in farmland soil and crops in the study area was evaluated by pollution index method,and the spatial distribution of pollution in the study area was studied by using ordinary Kriging spatial interpolation method.The health risk assessment of heavy metal pollution in farmland soil and crops in the study area was carried out by carcinogenic risk index method,non-carcinogenic risk index and dangerous commercial law,respectively.The conclusions are as follows:（1）Through the analysis and measuring of the content of soil and rice heavy metals in area,the soil was found that the range of change of As,Cd,Cu and Zn respectively was 25.56-44.87mg/kg、0.49-0.85mg/kg、42.39-80.40mg/kg and481.8-949.8mg/kg.the rice was found that the range of change of As,Cd,Cu and Zn respectively was 0.07-0.34mg/kg、0.04-0.56mg/kg、3.43-13.48mg/kg and30.32-96.49mg/kg.（2）The spatial distribution of heavy metal As and Cu in the soil of the study area was similar,in which the content of heavy metal Cd and Zn in the southeast and northeast region was higher than that in other regions.The spatial distribution of heavy metal Cd and Zn in crops is different,in which the concentration of heavy metal Cd in the northwest is lower than that in other regions,and the concentration of heavy metal Zn in the southern region is much higher than that in other regions.（3）The correlation analysis of the As、Cd、Cu and Zn of heavy metal elements in farmland soil and crops in the study area showed that the correlation coefficient between heavy metal As and Cu in soil was 0.492,and the correlation coefficient between Cu in soil and rice was 0.359,which showed a significant positive correlation.Therefore,it can be speculated that the source of heavy metal As and Cu in soil may be the same,and the enrichment of heavy metal Zn in rice has a certain relationship with heavy metal Cu in soil.（4）The single factor pollution index method and comprehensive pollution index method are used to calculate the contents of heavy metal As、Cd、Cu and Zn in farmland soil and crops in the study area.The results are as follows:the evaluation grade of heavy metal As、Cd and Cu single factor pollution in farmland soil in the study area is mild pollution,while the evaluation grade of heavy metal single factor pollution is severe pollution.The single factor pollution evaluation grade of heavy metal As and Cd in crops in the study area is mild pollution,and the pollution evaluation grade of heavy metal Cu and Zn is mild pollution.The comprehensive pollution evaluation grade of heavy metal As、Cd、Cu and Zn in farmland soil in the study area is moderate pollution,and the comprehensive pollution evaluation grade of heavy metal As、Cd、Cu and Zn in crops is mild pollution.（5）Using non-carcinogenic risk index and carcinogenic risk index methods to calculate the health risk index of heavy metal As、Cd、Cu and Zn in the soil of the study area,the results are as follows:the total non-carcinogenic risk of heavy metal As、Cd、Cu and Zn through all exposure pathways in the soil of the study area is7.10×10,respectively-2、4.50×10-4、9.18×10-4、1.47×10-3They are all acceptable risks and do not pose a non-carcinogenic risk to humans;the carcinogenic risk index for heavy metal As、Cd、Cu and Zn in soil in the study area totals 8.77×10-5is an acceptable risk of cancer.The risk quotient index of heavy metal As、Cd、Cu and Zn in rice in the study area was 1.37,1.22,0.91,0.52,respectively.Among them,heavy metal As and Cd can cause unacceptable health risk to human body,and the health risk caused by heavy metal Cu and Zn is acceptable. |
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