天水苹果园土壤重金属富集调查与污染评价

以天水市6个区县苹果园主产区为研究点，对其0~20 cm土壤pH 值、有机质和铜、锌、镉、铅、铬的含量及累积情况进行了检测及统计分析，并根据绿色食品产地土壤环境质量为标准，通过内梅罗综合指数法和污染负荷指数法对苹果园土壤环境质量进行了评价，结果显示：天水市苹果园土壤呈弱碱性，有机质含量均值为1.53%，所检测的5种重金属已有一定程度的积累，Cr、Pb、Zn均值都超过了甘肃省土壤的背景值；研究区土壤Cr、Pb、Cu三者在0.01和0.001水平具有显著正相关性，且这三种重金属与土壤有机质呈显著正相关；重金属累积的单项污染指数均小于1，内梅罗综合污染指数和污染负荷指数均在0.7以下，果园土壤环境质量完全满足绿色食品产地环境质量要求，其中Pb的累积对绿色苹果生产可能有较大的潜在影响，应加以有效控制以防止其持续累积。

Pollution Evaluation and Enrichment Investigation of Heavy Metals in Apple Orchard Soil of Tianshui Area

Six districts(counties) of apple orchard production area in Tianshui City (Qinxhou, Maiji, Qinan, Gangu , Wushan, Qingshui) were taken as the research sites. Where the pH and Concentrations of Cr, Cu, Pb, Cd, Zn and organic matter were investigated and analyzed with the help stastistical method in apple orchard topsoils(0~20cm) in Tianshui area. Simultaneously soil environmental quality was evaluated according to the environmental quality standards of green food production base methods of both the Nemerow comprehensive pollution index and pollution load index. The results indicate that the soil was slightly alkaline. and the average value of organic matter content is 1.53%, the content of these 5 metals were cumulated in the studied apple orchards, especially the average value of the element of Cr, Pb, Zn exceed the soil background value of the Gansu Province . The were significantly correlation among Cr, Pb, Cu and organic matter in apple orchard soils. Single factor index of all metals are less than 1and their multi-factor index and pollution load index were less than 0.7, its shows that the studied apple orchards meets the needs of the green food production base for furhter development, on the other hand, the content of Pb may have a potential negative influence to the green food production, therefore, real-time monitoring and protection measures were required to prevent its further enrichment.