设施蔬菜生产系统重金属积累特征及生态效应

摘要

To study spatial variability of soil heavy metals may help reveal effects of human activities on soil heavy metals accumulation and provide important basic data for soil utilization and its pollution risk assessment.Based on systematical analysis of heavy metals,arsenic (As),cadmium (Cd),copper (Cu),mercury (Hg),lead (Pb),zinc (Zn)in the environmental media,such as soil,irrigation water,fertilizer,and plants of a greenhouse vegetable production system typical of the suburbs of Nanjing,spatial variability and accumulation of heavy metals in the soil was explored causes of the accumulation analyzed,and effect of the accumulation on plant uptake of heavy metals in this system discussed.Results show that (1) accumulation of Cu,Hg,Pb,and Zn in the soil was significant compared with that in open fields,and the average contents of Cu,Hg,and Pb in the soil were higher than the criteria set in the Environmental Quality Evaluation Standard for Farmland in Greenhouse Vegetable Production ; (2) Large amounts of agro-inputs significantly affected spatial variability of soil properties,and hence,the spatial variability of soil Cu,Hg,Pb,and Zn in a similar way,for these elements were closely correlated with soil properties; and (3) The changes in soil properties and the accumulation of heavy metals strongly affected leaf vegetable' s uptake of heavy metals,and the former played a more important role.%研究土壤重金属的空间变异特征,可以揭示人为活动对土壤中重金属积累特征的影响,进而为土壤利用、污染风险评价提供重要的基础资料.选取南京市郊区一处典型的设施蔬菜生产系统为研究对象,测定了土壤、灌溉用水、肥料、蔬菜等介质中重金属砷(As)、镉(Cd)、铜(Cu)、汞(Hg)、铅(Pb)、锌(Zn)含量,研究了土壤中重金属的空间变异及积累特征,分析了积累产生的原因,讨论了系统中作物的重金属积累效应.结果表明:(1)与露天蔬菜地相比,设施蔬菜地土壤重金属Cu、Hg、Pb、Zn均产生明显的累积,且土壤中Cu、Hg、Pb平均含量超过温室蔬菜产地环境质量评价标准.(2)农用投入品的大量输入对土壤性质的空间变异产生了明显影响,而土壤Cu、Hg、Pb、Zn也呈现与之一致的空间变异特征,且这些元素与土壤性质存在显著相关性.(3)土壤性质的变化和重金属的积累对叶菜类作物重金属吸收影响较大,且前者更为重要.