北京园林绿地29种树木3种重金属含量的比较

Comparison of three heavy metal contents in 29 ornamental trees in Beijing garden green land

为了解园林树木对环境中重金属的富集能力,进而筛选出富集能力强的树种,以北京市陶然亭公园、中科院北京植物园、紫竹院公园为样地,采用ICP光谱仪测定了29种园林树木叶片和一年生枝条中重金属Cd、Pb、Cu的含量,对叶片和一年生枝条中重金属含量进行了相关性分析,并对园林树木富集3种重金属的综合能力进行了评价。结果显示:1)不同树种Cd、Pb、Cu的含量有显著差异;29种园林树木叶片和一年生枝条中Cd总含量为0.1017~0.2626mg/kg,Pb总含量为11.2606~40.5721mg/kg,Cu总含量为6.1819~26.2651mg/kg。2)采用系统聚类法,将29种园林树木对不同重金属含量分级归类,其中白扦和杜仲的Cd含量较高,砂地柏最低;白皮松和白扦的Pb含量较高,梓树最低;金银木和白扦的Cu含量较高,砂地柏最低。3)树木不同器官中重金属含量也不同,叶片与枝条中Cd含量有一定显著相关性,系数为0.316(P<0.01),Pb与Cu含量无显著相关性。4)采用隶属函数法对绿地中29种园林树木叶片和一年生枝条中Cd、Pb、Cu综合富集能力进行评价,发现白扦、金银木、贴梗海棠、太平花和暴马丁香综合富集能力较强。本研究以园林绿地成年园林树木为对象,对秋冬可凋落的叶片和可修剪的一年生枝条中重金属含量进行比较,对北京城市生态建设中的树种选择具有指导意义。

The purpose of this article was to understand the enrichment ability of ornamental trees to heavy metals in the environment and screen out the tree species with strong enrichment ability. The samples were from Beijing Taoranting Park, Beijing Botanical Garden, Purple Bamboo Park. The ICP spectrometer was adopted to determine the contents of heavy metals from autumn leaves and annual branches of 29 trees. The correlation between heavy metal contents in leaves and annual branches was analyzed. The comprehensive absorptive capacity in three heavy metals of 29 ornamental trees was compared. The results show that: 1) the contents of Cd, Pb, Cu in different species are significant differences, the content of Cd in leaves and annual branches from 29 garden trees ranged from 0.1017 to 0.2626mg/kg, Pb ranged from11.2606 to 40.5721mg/kg, Cu ranged from 6.1819 to 26.2651mg/kg;2) 29 kinds of trees’ different heavy metals were classified by cluster analysis, the Cd content of Picea meyeri and Eucommia ulmoides was higher, Sabina vulgaris was lowest, Pb content of Picea meyeri and Pinus bungeana was higher, Catalpa ovata was lowest, and Cu content of Picea meyeri and Lonicera maackii was higher, Sabina vulgaris was the lowest;3) the contents of heavy metals from different organs of trees were different. There was a significant correlation between Cd content in leaves and branches, and the coefficient was 0.316(P<0.01), and there was no significant correlation between Pb, Cu content in leaves and branches;4) the comprehensive enrichment ability of Cd, Pb and Cu in leaves and annual branches of 29 kinds of trees was evaluated by membership function method. The species with strong comprehensive absorbability to three heavy metals are Picea meyeri, Lonicera maackii, Chaenomeles speciosa, Philadelphus pekinensis and Syringa reticulata var. amurensis. In this study, the contents of heavy metals in autumn withered leaves and pruning annual branches of adult garden trees were compared, which has guiding significance for tree species selection in urban ecological construction in Beijing.