作 者 ：王慧,郭晋平*,张芸香,魏红芬,冯璐瑶
期 刊 ：生态学报 2010年 30卷 22期 页码：6218~6226
关键词：公路绿化带；重金属污染；污染指数；水平格局；防护效应；
Keywords:roadside tree-belt, heavy metal pollution, pollution index, dispersion pattern, protective effects,
摘 要 ：在山西省典型公路绿化路段路侧设置样带，在样带内按距离梯度采集路旁土壤并进行Pb、Cr、Cu、Zn重金属含量测定，采用污染指数分析4种重金属污染物的扩散格局及公路绿化带的影响，比较不同结构特征的绿化带对4种重金属污染防护效应的差异。结果表明，4种土壤重金属污染扩散格局呈单峰态，主要污染区间出现在10—70m范围内，4种重金属污染指数峰值与峰值位置不同；公路绿化带对土壤4种重金属污染有显著防护效应，可将污染限制在50m范围内，使峰值高度降低，峰值位置提前；绿化带宽度、郁闭度和树种组成对林带防护效应有显著影响，绿化带宽度在40—70m即可保证对路旁土壤重金属污染起到有效防护作用，单树种绿化带郁闭度≥0.6，可缩小重金属主要污染区间，100m处污染指数降为0.139—0.977；栽植混交林带使其成林后郁闭度≥0.6，对路旁土壤的重金属污染效果更好，可将重金属污染的峰值位置限制在20m范围内。
Abstract:Some typical roadside tree-belts were selected for this study in Shanxi Province. Concentration of heavy metals (Pb、Cr、Cu、Zn) in roadside surface soils along the tree-belts were measured using by ICP-AES. Pollution dispersion patterns of the four heavy metals were studied by pollution index which was the ratio of heavy metal concentrations in polluted soils against that in non-polluted background soil. Protective effects of different tree-belt structure types on soil heavy metals pollution were compared. The results showed: (1)The pollution dispersion patterns of the four heavy metals (Pb、Cr、Cu、Zn)were unimodal with the major pollution distance ranging from 10 to 70m. The peak values of pollution index and the peak positions of four heavy metal concentration were different. The peak value of pollution index of the four heavy metals was 2.297, 1.000, 2.019 and 0827. All the peak positions of the pollution values for the four heavy metals were not at road shoulders with the peak position of Cu at 20m from roads and that of Pb, Cr and Zn at 40m. (2) The roadside tree-belts had significant protective effects on the four heavy metal pollution. The pollution dispersion pattern of the four heavy metals had significant changes due to the influence of roadside tree-belt. T test showed significant difference (P＜0.001) in heavy metal concentration between roadside soils with tree-belts and without tree-belts (Pb、Cr、Cu、Zn).The pollution distance was limited mainly within 50m from the road. The concentration and pollution index of Pb, Cr and Cu was reduced with the peak value positions of Cr and Zn being shifted beforehand. The peak value positions of Cr and Zn were at 20m, with peak values of pollution index being 0.580 and 0.599, and peak values of concentration being 93945mg/kg and 108.549mg/kg. The peak value position of Cu was at 20m with the peak value of pollution index being 0.605 and the peak value of concentration being 54.511mg/kg. The peak value position of Pb was at 40m with the peak value of pollution index being 1.046 and the peak value of concentration being 46.940mg/kg. (3) Tree-belt width，shelterbelt porosity and species composition showed significant influence on heavy metal pollution protective effects of roadside tree-belts. The optimum tree-belt width was between 40 and 70m to effectively prevent the heavy metal pollution. Roadside tree-belts of mono-species with canopy density ≥0.6 could limit the main pollution ranges and reduce the pollution index of the 100m position to 0.139-0.977. Mixed tree-belt with canopy density ≥0.6 could be more effective to reduce roadside soil heavy metal pollution, limiting the peak value of pollution index within 20m. Moveover, the tree-belt with the mean height of main tree species ≥10m, could also prevent atmospheric fine particles spread, especially for Cu which often adheres to larger particles.
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