北京地区8种园林树木的叶片和枝条重金属含量比较

为了解不同园林树木重金属的吸收情况,以北京市陶然亭公园、中科院植物园、紫竹院公园、马甸公园、皇城根遗址公园和营城建都滨水绿道为样地,采用ICP光谱仪测定了8种园林树木叶片、一年生枝条以及相应土壤中重金属Cd、Pb、Cu的含量,并对叶片与一年生枝条中重金属含量以及树木与土壤重金属含量进行了相关性分析。结果表明,不同树种重金属含量有显著差异且因重金属种类而异;叶片和枝条中Cd含量排序为:紫薇金银木太平花锦带珍珠梅紫丁香木槿砂地柏,Pb含量排序为:锦带木槿太平花金银木紫丁香紫薇砂地柏珍珠梅,Cu含量排序为:金银木紫薇紫丁香珍珠梅木槿太平花锦带砂地柏;树木不同器官中重金属含量也不同,叶片与枝条中Pb含量具有显著相关性;树木叶片和一年生枝条的Cd、Pb、Cu重金属既来源于土壤,也来源于大气污染。8种园林树木中,对Cd、Pb、Cu吸收量最大的分别是紫薇、锦带和金银木;紫薇和金银木同时对Cd和Cu、太平花同时对Cd和Pb有较强的吸收力,而砂地柏吸收力较弱。本研究对园林绿地选择富集重金属能力强的树种有参考价值。

Comparison of Heavy Metal Contents in Leaves and Branches of Eight Ornamental Trees in Beijing Area

The purpose of this article is to understand the content and absorption characteristics of the cadmium (Cd), plumbum (Pb) and cuprum (Cu) from 8 ornamental trees in Beijing garden greens. The samples are from 6 sample sites of Beijing Taoranting Park, Beijing Botanical Garden, Purple Bamboo Park, Madian Park, Huangchenggen Ruins Park and Beijing Yingcheng Jiandu Waterfront Greenway. The ICP spectrometer was adopted to determine the contents of heavy metals from leaves, annual branches of 8 trees and corresponding soils. The correlation between heavy metal contents in leaves and annual shoots, as well as those in trees and soils were analyzed. The results show that the contents of heavy metals in different species are in significant differences and different from heavy metals species. The order of cadmium contents from 8 ornamental trees is: Lagerstroemia indica>Lonicera maackii>Philadelphus pekinensis>Weigela florida>Sorbaria sorbifolia>Syringa oblata>Hibiscus syriacus>Sabina vulgaris. The order of plumbum contents from 8 trees is: Weigela florida> Hibiscus syriacus>Philadelphus pekinensis>Lonicera maackii> Syringa oblata>Lagerstroemia indica>Sabina vulgaris>Sorbaria sorbifolia. The order of cuprum contents from 8 trees is: Lonicera maackii>Lagerstroemia indica>Syringa oblata>Sorbaria sorbifolia >Hibiscus syriacus>Philadelphus pekinensis>Weigela florida> Sabina vulgaris. The contents of heavy metals from different organs of trees are different. The plumbum contents of leaves'' and annual shoots is significantly correlated. Cd, Pb and Cu in tree leaves and annual branches come from soil as well as the air pollution. Among 8 ornamental trees, Lagerstroemia indica, Weigela florida and Lonicera maackii had the highest absorption of Cd, Pb and Cu respectively. Lagerstroemia indica and Lonicera maackii had a strong absorption of both Cd and Cu. Philadelphus pekinensis had a strong absorption of both Cd and Pb, while Sabina vulgaris had a weak absorption. There was reference value for the selection of tree species for heavy metal enrichment in green space in this study.