采用污染指数分析7种重金属元素(Pb、Cr、Cu、Zn、Cd、Ni、As)的扩散格局及其对防护林带的影响,比较有林带和无林带路旁土壤重金属污染的差异.结果表明,有林带和无林带路旁土壤重金属含量峰值均不在路肩处,其中无林带路段大部分出现在距路肩100 -200 m的范围,然后逐渐下降到对照值,而有林带路段大部分出现在距路肩10 -50m的范围,且在越过峰值以后各样点的含量值基本上比无林带对应样点的低,并达到显著水平;单项污染综合指数显示,在无林带路段,除了Cr和Ni,其他重金属元素对路旁200m范围内的土壤均产生了不同程度的污染,其中以Zn和Cu的污染最严重,有林带路段重金属污染范围大部分缩小为100 m;多项污染综合指数显示,无林带路段路旁土壤重金属污染的范围达到300m,而有林带路段缩小为200m;相关性分析显示,土壤重金属污染主要来源于公路交通,根据当前沿海防护林的经营管理方式,在公路两侧建设50 m宽的防护林带,能有效抑制由交通引起的重金属污染的扩散.%Seven heavy metals (Pb, Cr, Cu, Zn, Cd, Ni, As) were investigated by pollution index which was the ratio of heavy metal concentrations in polluted soils against that in non-polluted background soil between forest region and non-forest region, compared the different pollution effects among them. The results showed as follows. (1) The highest concentrations of most heavy metals in non-forest region, except for Zn in soils, were at 100 to 200 m away from the roadbed, then gradually decreased to the control values. But in forest region which was at 10 to 50 m away from the roadbed. The concentrations of soil heavy metals in other sampling lite* behind the highest concentrations of the forest region were significantly lower than the corresponding sampling sites at non-forest region. (2) The index of single-pollution showed, except for Cr and Ni, the incidence of all heavy metal elements in non-forest region achieved 200 m from the roadbed, Zn and Cu were the most serious pollution in this region. But in forest region, the incidence reduced to 100 m. (3) The index of multi-pollution showed, the incidence of heavy metal pollution in non-forest region achieved 300 m from the roadbed, which reduced to 200 m in forest region. (4) The correlation analysis showed, the heavy metal pollution in soil mainly derived from the road traffic, according to the current coastal protection forest management, on both sides of the road, constructing 50 m width shelterbelts can effectively inhibit the diffusion of heavy metal pollution which caused by traffic.
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