贵州草海湿地周边耕地土壤与农作物重金属污染特征

采集草海湿地周边主要农作物可食部分及对应根系的土壤样品，分析测试了重金属Cd，Cr，Hg，Pb，As和Zn的含量，对比研究了土壤和作物中重金属污染水平及对重金属的富集能力。结果表明:土壤重金属元素Zn，As，Cr平均含量未超过贵州省土壤元素背景值，其他3种重金属Pb，Cd，Hg平均值分别是背景值的1.24，1.44，7.5倍；与中国《食品中污染物限量》标准相比，除Hg平均含量超标外，蔬菜中As，Cr，Zn，Cd和Pb平均含量处在可接受范围内。6种重金属的单因子污染指数的高低依次是Hg > Pb > Cd > As > Cr > Zn，葱和萝卜处于安全水平，其余农作物处于警戒线；不同种类作物中重金属富集特征差异较大，菠菜对As，Cd，Hg，Pb的富集系数比其余作物高，萝卜叶对Cr和Zn的富集能力较强，重金属Cr富集系数最低的是玉米，Zn和Hg富集系数最低的是萝卜根，Cd和Pb富集系数最低为马铃薯，As富集能力最低的为白菜。

Characteristics of Heavy Metal Pollution in Crops and Soil around Caohai Wetland in Guizhou Province

The edible parts of main crops and the corresponding root-zoning soil samples around the part of wetland in Caohai were collected to analyze and test the contents of Cd, Cr, Hg, Pb, As and Zn, and the enrichment abilities on heavy metals in test crops and the pollution level of heavy metals in soils and crops were studied and contrasted. The results showed that the average contents of soil heavy metal Zn, As, Cr did not exceed the background values in soils in Guizhou Province, the average values of other 3 kinds of heavy metals Pb, Cd, Hg were 1.24, 1.44, 7.5 times of the background values; compared with the standard of ‘China Food Contaminants’, the average content ranges of As, Cr, Zn, Cd and Pb in vegetables were acceptable. The level of single factor pollution about six kinds of heavy metals decreases in the order Hg > Pb > Cd > As > Cr > Zn, the levels of these metal in onions and radishes are at the safe level, other crops in a cordon line; the enrichment characteristics of heavy metals of different types of crops were obviously different, the enrichment coefficients of Cd, Hg, As, Pb in spinach are higher than other crops, the accumulation ability of heavy metals on Cr and Zn of radish leaves were stronger, the enrichment coefficients of Cr in maize was the lowest, the enrichment coefficient of Zn and Hg in the radish root is lowest, the enrichment coefficients of Cd and Pb in potato was the lowest, the enrichment coefficients of As in cabbage is the lowest.