北京园林绿地6种树木的叶片和一年生枝中5种重金属含量比较

为了解不同园林树木对重金属的吸收情况，以北京市陶然亭公园、紫竹院公园、中科院植物园、马甸公园、皇城根遗址公园和营城建都滨水绿道不同环境绿地为样地，选择样地间共有的园林树木，采用ICP光谱仪测定了6种树木叶片和一年生枝条中重金属锌(Zn)、铬(Cr)、镍(Ni)、砷(As)和汞(Hg)的含量，以此为基础，采用隶属函数法将6种树木单位重量对5种重金属的综合富集能力进行排序，并对同树种叶片与当年生枝、5种重金属吸收量分别进行相关分析。结果表明：1)不同树种叶片和一年生生枝条单位重量中重金属含量有显著差异，且因重金属种类而异。Zn、As含量最高的为金银木，Cr、Ni、Hg含量最高的依次为圆柏、侧柏、丁香；丁香富集Zn、Cr、As的能力最低，白皮松富集Ni能力最低，侧柏富集Hg能力最低。2)树木叶片和当年生枝单位重量对5种重金属综合富集能力排序为：金银木＞侧柏＞圆柏＞油松＞丁香＞白皮松。其中，针叶树种中圆柏、侧柏、油松富集5种重金属的综合能力显著高于白皮松(P＜0.01)，阔叶树种中金银木吸收重金属的能力显著高于丁香(P＜0.01)。3)树木不同器官中重金属含量也不同，不同树种间叶片与枝条中仅Cr含量具有显著相关性，相关系数为0.461(P＜0.01)，其他4种元素均未达到显著水平。4)同树种叶片和当年生枝Cr和Ni吸收呈极显著相关性(P＜0.01)，其他元素吸收之间未呈现相关性。本研究结果对北

Comparison of Five Heavy Metals Contents in Leaves and Annual Branches of Six Ornamental Trees in Beijing Garden Green Space

In order to understand the absorption of heavy metals by the aboveground organs of different garden trees, six garden trees were selected from six sample plots of Taoranting Park, Purple Bamboo Park, Beijing Botanical Garden, Madian Park, Huangchenggen Ruins Park and Yingcheng Jiandu Waterfront Greenway in Beijing. Based on the absorption of heavy metals per unit of tree leaves and annual branches, the contents of heavy metals Zn, Cr, Ni, As and Hg in leaves, annual branches of trees were determined by ICP spectrometer. The comprehensive enrichment ability of heavy metals per unit weight of trees to five heavy metals in six trees was ranked by subordinate function value analysis. The correlation analysis of the heavy metals content between leaves and annual branches, and of the five kinds of heavy metals absorbed were done respectively. The results show that: 1) the contents of heavy metals in leaves and annual branches from 6 species were significantly different, depending on the types of heavy metals: the highest contents of Zn and As was Lonicera maackii, Cr, Ni and Hg were Sabina chinensis, Platycladus orientalis and Syringa oblata; the lowest concentration of Zn, Cr and As was found in Syringa oblata, Ni was found in Pinus bungeana and Hg was in Platycladus orientalis. 2) The comprehensive enrichment ability of five heavy metals in per unit of the leaves and annual branches of six species is: Lonicera maackii > Platycladus orientalis > Sabina chinensis > Pinus tabuliformis > Syringa oblata > Pinus bungeana. Among them, the comprehensive ability of accumulating five heavy metals in Coniferous species, Sabina chinensis, Platycladus orientalis and Pinus tabulaeformis, was significantly higher than that of Pinus bungeana (p < 0.01). The ability of absorbing heavy metals in broad-leaved species, Lonicera maackii was significantly higher than that of (p < 0.01). 3) The contents of heavy metals in different organs of trees were also different. There was a significant correlation between the contents of Cr in leaves and branches. The correlation coefficient was 0.461 (p < 0.01). The correlation between the contents of heavy metals in leaves and branches of other four elements was not significant. 4) The correlation coefficient of 5 heavy metals absorbed by leaves and branches showed that Cr Ni was highly significant (p < 0.01). This study has reference value for selecting tree species with strong ability to enrich heavy metals in the air in garden green space of Beijing.