设施菜地和露天菜地的土壤重金属含量及累积特征

Contents and accumulation characteristics of heavy metals in open and protected vegetable soils

【目的】比较分析不同种植年限的设施菜地和露天菜地土壤重金属的污染特征,为菜地管理及土壤重金属污染治理提供科学依据。【方法】以豫西洪积平原洪庄杨乡附近的露天菜地和设施菜地土壤为研究对象,大田土壤为对照,以种植年限(0～4,5～9,10～19,≥20年)为采样依据,测定8种土壤重金属(Cu、Zn、Cr、Ni、Pb、Cd、As、Hg)的含量,并运用地累积指数和内梅罗指数,对研究区设施菜地和露天菜地的土壤重金属含量及其累积特征进行综合分析。【结果】①2类菜地土壤重金属Cu、Ni、Pb、Cd和Hg含量存在不同程度的超标,而大田对照土壤除Ni外,其他各重金属含量均不超标;除Ni元素外,露天菜地和设施菜地土壤重金属含量均具有随种植年限增加而增大的趋势,而露天菜地则由于易受外界条件影响而在总体增大趋势之下呈现一定的波动性。②露天菜地和设施菜地土壤均存在Pb、Hg、Cd的累积污染,其程度大小均为Hg>Cd>Pb,且随种植年限的增加累积污染程度增大。③露天菜地和设施菜地土壤均达到了重金属强度污染水平,且均随种植年限的增加而呈加重态势,露天菜地土壤重金属综合污染指数较设施菜地高。【结论】研究区菜地土壤已产生不同程度的重金属累积污染,露天菜地和设施菜地具有大致相似的污染特征,累积污染均随种植年限增加而加重,但外源性因素对露天菜地重金属污染的影响更广泛。

[Objective] The comparative analysis of heavy metal contaminations in open and protected vegetable lands with different planting years was conducted to improve management of vegetable lands and prevention of metal pollution in soil. [Method] Open and protected vegetable soils on alluvial plain at Hongzhuangyang village in western Henan province were taken as research material and the soil from field was used for comparison. Based on cultivation years including four groups.0 to 4 years, 5 to 9 years, 10 to 19 years and ≥20 years,the concentrations of Cu,Zn,Cr,Ni,Pb,Cd,As and Hg were analyzed. Heavy metal contents and their accumulation characteristics for open and protected vegetable soils were evaluated using geo-accumulation index and Nemerow integrated index. [Result] （i） The concentrations of Cu, Ni, Pb,Cd and Hg in both open and protected vegetable soils exceeded the standards to different extents,while the concentrations of all metals except Ni in soil from field did not. Except Ni, the amounts of heavy metais be- came higher as the planting years increased. However, the concentrations of some heavy metals in open vegetable fields showed certain fluctuation due to external influence. 2 Concentrations of Pb, Hg and Cd accumulated in both open and protected vegetable soils in an order of Hg）Cd）Pb. Furthermore,the degrees of accumulation pollution increased with the increase of planting years. （3） The concentrations of heavy metals in both open and protected vegetable fields reached the pollution level of strong. At the same time, the pol- lution levels had an aggravation tendency as the increase of planting years. The integrated pollution index of open vegetable land was higher than that of protected vegetable land. [Conclusion] Vegetable soils in studied area have produced aecumulation pollution of heavy metals. The open vegetable land and protected vegetable land present similar pollution characteristics, and the accumulation pollution aggravates with the increase of planting years. However,exogenous factors play a more extensive role on heavy metal pollution in the open vegetable land.