道路绿地土壤重金属含量水平分布特征

目的]研究道路绿地对交通重金属污染的防护作用。方法]在重庆市五黄路乔草混交林绿地和草坪绿地两种样地内,分别采集距离道路一定梯度的表层土壤样品,测定样品中重金属Pb、Cd、Cr、Mn、Hg、As、Cu、Zn、Fe含量,分析两种配置模式下绿地土壤重金属含量的水平分布特征。结果]9种重金属在道路绿地土壤中的水平分布特征表现各异,其中Cd、Pb、Cr、Zn是交通对绿地土壤污染的主要重金属因子。与草坪绿地相比,乔草混交林绿地在同一水平距离的土壤Pb、Cd、Cr、Cu、Zn含量水平、含量峰值均明显降低,其中Pb、Zn含量峰值降幅最大。随着与道路距离的增加,主要重金属含量总体呈下降趋势。草坪绿地重金属污染带主要集中在距离道路1～80m的范围内,乔草混交林绿地的重金属污染带主要集中在距离道路1～30 m的范围内。结论]栽植乔木可以提高绿地对交通重金属污染的防护作用。

Horizontal Distribution Characteristics of Heavy Metals in the Soil of Road Green Spaces

Objective] The study aimed to discuss the effects of road green spaces on heavy metal pollution. Method ] Surfhce soil samples were collected from a green lawn and a green space with trees and grasses on Wuhang Road in Chongqing City, and the contents of Pb, Cd, Cr, Mn, Hg, As, Cu, Zn and Fe in the soil were measured to analyze the horizontal distribution characteristics of heavy metals in the soil of two road green spaces. Result] The horizontal distribution characteristics of 9 heavy metals in the soil of the two road green spaces were different, and the main factors for heavy metal pollution were Cd, Pb, Cr and Zn. Compared with the green lawn, the contents and peaks of Pb, Cd, Cr, Cu and Zn in soil of the green space with trees and grasses decreased significantly, and the peaks of Pb and Zn dropped greatest. In addition, the contents of major heavy metals went down with the increase of the distance from a sampling point to the road. Heavy metal pollution of the green lawn mainly appeared at a distance of 1 - 80 m, while that of the green space with trees and grasses distributed at a distance of 1 - 30 m. Conclusion] Planting trees can improve the effects of aTeen spaces on heavv metal pollution.