南京城郊零散菜地土壤与蔬菜重金属含量及健康风险分析

Contents of heavy metals in soils and Chinese cabbages (Brassica chinensis) from some urban vegetable fields around Nanjing and the human health risks

采集南京城郊零散菜地土壤和青菜配对样品各18个,用原子吸收光谱仪测定了铜、锌、铅、镉的质量分数。结果表明,南京城郊零散菜地土壤中Cu、Zn、Pb、Cd质量分数的变化范围分别为39.38±9.85、254.79±132.77、67.77±57.52、1.03±1.28 mg/kg;重金属质量分数在土样之间存在较大的变异性,反映了人为活动已对南京城郊土壤重金属污染产生了明显的影响。在城郊零散菜地土壤上种植的青菜,其叶中Cu、Zn、Pb、Cd质量分数的变化范围分别为5.00±1.57、62.21±16.05、5.90±3.09、0.73±0.39 mg/kg,其中Pb、Cd质量分数全都超过国家食品卫生标准。依据USEPA推荐的RfD值和我国居民平均食物消费结构进行计算,结果表明这些零散菜地的蔬菜重金属污染可能给食用者带来健康风险;食用其中一些污染严重的蔬菜而摄入Pb、Cd引起的健康风险分别高达90.66%和42.17%。

Increasing population is facing the environmental pollution in urban area with the urbanization in China since the last two decades. However, a portion of urban people relies on the vegetables grown in local fields around city but the health risks by consuming them have been hardly discussed. In this paper, 18 paired samples both of soils and Chinese cabbages grown in urban fields were sampled and the contents of Cu, Zn, Pb and Cd were digested and determined by AAS. The soil contents of Cu, Zn, Pb and Cdvaried in the range of 39.38±9.85, 254.79±132.77, 67.77±57.52, 1.03±1.28 mg/kg respectively. Whereas, the contents in leaves of Chinese cabbages were 5.00±1.57, 62.21±16.05, 5.90±3.09, 0.73±0.39 mg/kg,with the later two elements exceeding the national hygienic limits for foods. A calculation with the RfD values recommended by USEPA showed high human health risk from consuming these Chinese cabbages under a Chinese diet. The highest rate of contribution to RfD of Pb and Cd of severely polluted vegetable samples amounted to 90.66%, 42.17% respectively.