行道树对武夷山公路边茶园重金属污染的防护效果

摘要

In order to study protective effect of roadside tree lines on heavy metals pollution (Pb,Zn,Cd,Cu,Cr and Mn) to roadside tea gardens in Wuyishan,samples of soils and tea leaves were collected from two neighboring sections of a roadside tea plantation,of which one has a roadside tree line (Section B) and the other does not (Section A).With an ICP-MS,concentrations of these heavy metals in the samples were measured.Correlation analysis and principal component analysis of heavy metals in the soil and tea leaves differed in result between Section A and Section B,which may be attributed to the effect of the roadside tree lines intercepting pollutants from the road.The principal component analysis reveals that concentrations of the six heavy metals in the samples,that Pb,Cu and Zn was mainly affected by traffic,while that of Mn and Cr by both traffic and geological background,and that of Cd by both traffic and fertilization.Moreover,it was also found that a single row of fir trees along the roadside in Section B could reduce not only the mean concentrations of heavy metals in the tea trees 1-150 m away from the roadbed,but also the range of maximal concentrations of Zn and Pb alongside the road from 50-80 m down to l-10 m,which was possibly attributed directly to the effect of the roadside tree line intercepting pollutants from the traffic and indirect to its interception of carbonate dispersal affecting soil pH.Obviously,decreasing the concentrations of traffic related heavy metals in tea and improving quality of the tea in roadside tea gardens can be achieved through planting roadside trees alongside the road in the tea gardens.%比较了武夷山路边茶园无行道树(A区)和有行道树(B区)的2个区域土壤和茶叶中Pb、Zn、Cd、Cu、Cr、和Mn含量随距路基距离变化的趋势.结果显示:行道树的截留对于重金属的相关性和主成分分析结果有重要影响.6种重金属中Pb、Cu、和Zn主要受交通环境影响,Mn和Cr受土壤母质和交通环境的影响,Cd受肥料与交通环境的影响.A区茶叶中重金属分布最能反映交通相关源重金属的扩散结果,Pb和Zn的最大含量值出现在距路基50～80 m区域.不论何种来源的重金属,单行杉树都能使距路基1～ 150 m区域的茶园内茶叶重金属平均含量降低22％～37％,也能使Pb和Zn的最大含量值区域从距路基50～80 m减小到1～10 m.这可能与行道树直接影响重金属的扩散和通过影响碳酸盐污染物扩散而间接影响路边土壤pH值的双重作用有关.在靠近公路的茶树种植区建立适当的绿篱有助于减少茶树中交通源重金属的污染,提高茶叶质量.