豫北典型农田作物中重金属污染状况及健康风险评价

Pollution of Heavy Metals in Typical Crops of Northern Henan Province and Health Risk Assessment

农产品污染引发的食品安全问题目前已经成为全社会关注的焦点,为了研究和评价农作物中重金属污染和健康风险状况,采集了焦作市武陟县玉米、水稻和花生三种大田作物样品,共计47个样品,其中玉米样品16个,花生样品4个,水稻样品27个。在测定作物籽粒中重金属Cr、Ni、As、Cd和Pb含量的基础上,分别采用单因子污染指数和综合污染指数法评价了作物籽粒中重金属的污染状况,并运用危险商(HQ)法评价了这些作物中的重金属对人体健康可能造成的风险,进而应用相关分析法、聚类分析法及主成分分析法,探讨了作物籽粒中重金属含量的分布特征及其污染来源。结果表明:武陟县农田作物籽粒中的Cr、Ni、As、Cd和Pb的平均含量分别为0.26±0.42、0.31±0.29、0.04±0.03、0.01±0.04和0.03±0.03 mg·kg-1。其中,玉米籽粒中的Cr、Ni、As、Cd和Pb的平均含量分别为8.86×10-2±0.21、9.41×10-2±0.12、8.10×10-3±5.29×10-3、1.20×10-5±4.92×10-5和0.04±0.02 mg·kg-1;水稻籽粒中的Cr、Ni、As、Cd和Pb的平均含量分别为0.38±0.49、0.44±0.31、0.07±0.02、4.60×10-3±7.42×10-3和0.03±0.03 mg·kg-1;花生籽粒中的Cr、Ni、As、Cd和Pb的平均含量分别为0.13±0.22、0.32±0.16、0.02±3.05×10-3、0.11±0.07和1.32×10-2±1.70×10-2 mg·kg-1。农作物籽粒中各重金属元素的单因子污染指数评价结果显示,从总体上看,3种农作物籽粒中5种重金属的单因子污染指数均值均小于1,单因子污染指数均值大小顺序为:Ni>As>Cr>Pb>Cd;从作物类型来看,玉米和水稻中Ni超标的样品比率分别为6.67%和51.85%,水稻中Cr超标的样品比率为12%。农作物籽粒中各重金属元素的综合污染指数评价结果显示,重金属的平均综合污染指数为0.59,整体上处于安全等级。总体来看,14.89%的农作物受到不同程度的污染,其中轻度污染的农作物占10.64%,中度污染的农作物占4.25%,19.15%的农作物处于警戒限。重金属污染程度以水稻最为严重,轻度污染的为18.52%,中度污染的为7.41%,另外有29.63%处于警戒限内。健康风险评价结果显示,对于成人和儿童而言,5种重金属的健康风险指数均小于1,不会造成当地成人和儿童的健康风险,但重金属通过本地谷物类和豆类产品摄入对成人造成的健康风险略高于儿童。农作物籽粒中5种重金属的相关性分析表明,Cr-Ni和As-Ni在作物籽粒中存在极显著正相关性,Cr-As存在显著的正相关性。聚类分析发现,Cr和Ni可以聚为一类,有可能存在共同的来源。针对玉米的主成分分析表明,玉米中5种重金属可以由2个主成分来反映,第一主成分主要支配着玉米籽粒中Cr、Ni、As和Cd的来源。第二主成分支配Pb,其来源与其他重金属元素有较大区别。

Food safety issues induced by pollution of agricultural products has become the social concern. To assess the pollution status and human health risks induced by heavy metals in corps, 47 samples, including 16 corn samples, 27 rice sanples, and 4 peanut samples, were collected from typical farmland in Wuzhi County. After the analysis of Cr, Ni, As, Cd, and Pb contents in the samples, single factor pollution index and comprehensive pollution index were calculated to assess the quality of corps. Furthermore, the potential health risk induced by intake of heavy metals through consumption of corps was evaluated using hazard quotient（HQ）. Correlation analysis, clustering analysis and principle component analysis were conducted to identify the sources and distribution of these heavy metals in the corps. It was found that the average concentrations of Cr, Ni, As, Cd, and Pb in the corps were 0.26±0.42, 0.31±0.29, 0.04±0.03, 0.01±0.04, and 0.03±0.03 mg·kg^-1, respectively. With respect to corn, the average concentrations of Cr, Ni, As, Cd, and Pb were 8.86×10^-2±0.21, 9.41×10^-2±0.12, 8.10×10-3±5.29×10^-3, 1.20×10^-5±4.92×10^-5, and 0.04±0.02 mg·kg^-1, respectively. As for rice, the average concentrations of Cr, Ni, As, Cd, and Pb were 0.38±0.49, 0.44±0.31, 0.07±0.02, 4.60×10^-3±7.42×10-3, and 0.03±0.03mg·kg-1, respectively. The average concentrations of Cr, Ni, As, Cd, and Pb in the peanuts were 0.13±0.22, 0.32±0.16, 0.02±3.05×10^-3, 0.11±0.07, and1.32×10^-2±1.70×10^-2, respectively. Single factor pollution indices of Cr, Ni, As, Cd, and Pb were smaller than 1 with an decreasing order of Ni〉As〉Cr〉Pb〉Cd.6.67%of the corns samples and 51.85%of the rice samples have Ni concentrations higher than the Standard of Maximum levels of contaminants in foods（GB2762-2005）. In addition, 12%of the rice samples have concentrations of Cr higher than the Standard. The average comprehensive pollution index was 0.59, indicating that the corps have not been polluted. In general, about 14.89%of the samples were subjected to pollution of different degrees. Specificly, 10.64%of the samples were slightly polluted, 4.25%were moderately polluted, and 19.15%of the samples were categorized into the warning level. In the 3 crop species studied, rice was polluted most heavily, with 29.63%, 18.52%, and 7.41%of the samples falling into the categaries of warning level, slight, and moderate pollution, respectively. Health risk indices of these heavy metals were smaller than 1 for both adults and children, indicating that the health risk induced by intake of heavy metals through crops comsumption could be ignored. The health risk for adults was higher than that for children. Highly positive correlations of Cr-Ni and As-Ni, and positive correlation of Cr-As in the corp samples were established significantly. Clustering analysis revealed that Cr and Ni might have originated from similar sources. Principle component analysis revealed that the first main component dominated the sources of Cr, Ni, As, and Cd, while the second main component, Pb, might have originated from sources different from that of other heavy metals.