典型喀斯特区稻田土壤重金属Cd、Pb污染及膳食风险评价

为探究典型喀斯特粮食产区稻田土壤和稻谷重金属(Cd、Pb)的污染现状及膳食摄入风险，本研究选取黔中腹地贵州省息烽县作为研究区，采用单因子污染指数法、内梅罗综合指数法和地累积指数法对该区53组稻田土壤样品的重金属(Cd、Pb)含量进行分析和评价，并利用危险商(HQ)法对研究区稻谷进行膳食摄入风险评价。结果表明：息烽县稻田土壤中重金属含量表现为Pb>Cd, Pb和Cd的平均含量分别为33.74 mg·kg^-1和0.42 mg·kg^-1,均低于国家农业土壤限制值；单因子污染指数(P_i)的平均值均小于1,说明多数样品点位处于无污染水平；内梅罗综合指数法评价结果显示，息烽县稻田土壤中存在中度重金属综合污染现象；地累积指数法结果显示，息烽县90%以上土壤属于无污染级别，稻田土壤中无显著的重金属累积迹象。稻田土壤和稻谷中Cd、Pb变异系数均处于强变异，稻田土壤中Cd、Pb呈显著正相关关系。膳食评价结果显示，稻谷中Cd、Pb的平均危险商值表现为Pb

Heavy Metal Cd and Pb Pollution and Dietary Risk Assessment in Paddy Soil of Typical Karst Area

In order to explore the pollution status and dietary intake risk of heavy metals (Cd, Pb) in paddy soil and rice in typical karst grain producing areas, Xifeng County in central Guizhou Province was selected as the study area in this study. The contents of heavy metals (Cd, Pb) in 53 groups of samples in the study area were analyzed and evaluated by single factor pollution index method, Nemerow comprehensive index method and geo-accumulation index method, and the dietary intake risk of rice in the study area was evaluated by Hazard Quotient (HQ) method. The results showed that the content of heavy metals in the paddy soil of Xifeng County was Pb>Cd, and the average contents of Pb and Cd was 33.74 mg·kg^-1 and 0.42 mg·kg^-1, respectively, which was lower than the national agricultural soil limit value. The average value of single factor pollution index (P_i) was less than 1, indicating that points of the most samples were at a pollution-free level. The results of Nemerow evaluation showed that there was a moderate comprehensive pollution of heavy metals (Cd, Pb) in the paddy soil of Xifeng County. The results of geo-accumulation index showed that more than 90% of the soil in Xifeng County belonged to non-pollution level, and there was no significant accumulation of heavy metal in paddy soil. The variation coefficients of Cd and Pb in paddy soil and rice were in strong variation, and Cd and Pb in paddy soil were significantly positively correlated. The results of dietary evaluation showed that the average hazard quotient of Cd and Pb in rice was Pb