黄河兰州段黄灌区蔬菜大棚土壤重金属含量分析及污染评价

Analysis and Evaluation on Heavy Metal Contaminated Soils in Vegetable Greenhouses of Irrigation Area of Lanzhou Section of the Yellow River,China

以Pb、Cu、Cr、As四种重金属元素为评价因子,依据国家土壤环境质量二级标准和兰州市土壤背景值,分别用单因子指数法、内梅罗综合指数法以及地积累指数（Igeo）法,对黄河兰州段黄灌区蔬菜大棚土壤重金属含量进行研究。结果表明：黄灌区蔬菜大棚土壤0~20 cm土层中Cu和Cr分别超过兰州市土壤背景值的176.20%、264.91%。从单因子污染指数看,兰州段上中下游三个黄灌区土壤重金属的单因子污染指数均在1以下,未被污染,属安全范围。从综合污染指数分析,三区的综合污染指数均小于0.7,属安全范围。整个兰州段上中下游黄灌区蔬菜大棚土壤重金属综合污染指数为0.4957,属安全范围。从地积累指数结果来看,三区蔬菜大棚土壤中Cr达到了轻度—中度污染。

Four heavy metals（i.e.,Pb,Cu,Cr,and As） were analyzed in samples obtained from the heavy metal contaminated soils in vegetable greenhouses of the irrigation area located at the Lanzhou section of the Yellow River.The indices of single pollution,Nemerow pollution,and Geoaccumulation were used to evaluate the content of heavy metal contaminated soils.The results showed that Cu and Cr contents in the 0-20 cm soils of vegetable greenhouses of irrigation district were more than 176.20% and 264.91% higher than the background values of the soil of Lanzhou.The single factor pollution index was less than 1 in each studied area,which indicating all these three areas were safe based on the regulatory requirements.The Nemerow pollution index in each three districts was less than 0.7 within the safe range.The heavy metal pollution index in vegetable greenhouses in the whole Lanzhou section of the Yellow River was 0.4957 within the safe range.Based on the index of Geoaccumulation,Cr reached mild-moderate pollution in all three studied areas.