洛川苹果园地土壤重金属污染调查与评价

Investigation and Assessment on Heavy Metals Pollution of Soil in Luochuan Apple Orchard

通过对洛川苹果园地土壤样品的采集、监测,依据无公害果园产地土壤环境质量标准和绿色食品产地土壤环境质量标准,重点分析评价了对土壤环境及人体危害较大的Cd、As、Cr、Pb等重金属元素的污染现状。评价结果表明:以无公害果园产地土壤环境质量为评价标准,洛川苹果园地土壤重金属污染程度有As>Cr>Cd>Pb的特征,土壤重金属综合污染指数为0.51,土壤Cd、As、Cr、Pb单项污染指数平均值均小于0.7,土壤环境中的重金属元素含量现状水平符合无公害苹果生产的要求;以绿色食品产地土壤环境质量为评价标准,洛川苹果园地土壤重金属污染程度有As>Pb>Cr>Cd的特征,土壤重金属综合污染指数为0.64,土壤Cd、Cr、Pb单项污染指数平均值均小于0.7,土壤As单项污染指数平均值大于0.7,但小于1。土壤环境中的重金属含量现状水平符合绿色食品苹果生产的要求。但土壤As单项污染指数平均值为0.74,已超过绿色食品产地土壤污染警戒线。洛川苹果园地土壤重金属As污染程度较高,主要是由于人为长期不合理使用含As农药、化肥所致。因而,洛川苹果生产中应将土壤环境中的As作为严控的土壤污染物。

The monitored soil samples were collected from Luochuan apple orchard. According to the environmental quality standard for soils in the producing area of the nuisance free fruits orchard and the green food, this thesis evaluated the pollution status of heavy metals （Cd, As, Cr and Pb） by using single-factor index and synthetic pollution index methods. The results indicated that the contaminated degree of soil heavy metals has the feature of As〉Cr〉Cd〉 Pb, the synthetic pollution indices of soil heavy metals was 0.51, the mean value of single-factor indices of soil heavy metals in all soil samples was less than 0.7, so the heavy metal contents in soil environment was in a good condition in Luochuan apple orchard, and it was suitable for the demand of the nuisance free apple production by the environment quality standard for soils in the producing area of the nuisance free fruits. The contaminated degree of soil heavy metals had the feature of As〉Pb〉Cr〉Cd, the synthetic pollution indices of soil heavy metals is 0.64, the mean value of single-factor indices of Cd, Cr and Pb of all soil samples was less than 0.7, the mean value of single-factor indices of As in all soil samples are bigger than 0.7, but it is less than 1. So the heavy metals contents in soil environment was in a good condition in Luochuan apple orchard, and it is suitable for the demand of the green food apple production by the environment quality standard for soils in producing area of the green food. However, the mean value of single-factor indices of As was 0.74, being at the warning limit of the environment quality standard for soils in producing area of the green food. As in soils was in a higher contaminated degree in Luochuan apple orchard, which was mainly caused by the long-term irrational use of As contained pesticides and chemical fertilizers, therefore, As pollutant in soils should be controlled strictly for developing apple production in Luochuan apple productive base.