城镇绿化树种叶片滞尘与重金属积累能力研究——以浙江省余姚市泗门镇为例

目的]通过实地取样测定浙江省余姚市泗门镇的工业区、商业交通区和休闲娱乐区3个功能区9种常见绿化树种叶片的滞尘量、叶片重金属含量和叶面尘重金属含量,了解长江以南地区城镇常用绿化树种滞尘及重金属吸收能力的差异。方法]采用重量差值法测定叶片滞尘量,用电感耦合等离子体质谱仪测定叶面尘和叶片重金属含量,用主成分分析法解析叶面尘的重金属来源,分析叶片重金属含量与叶面尘重金属含量的关系。结果](1)不同绿化树种的滞尘能力差异显著,夹竹桃、海桐和紫薇滞尘能力较强;(2)同一绿化树种在不同功能区的叶片滞尘量和叶片重金属含量存在很大差异,叶片单位面积滞尘量和叶片重金属含量随着环境污染程度的增加而升高;(3)叶面尘重金属在各功能区具有很高的同源性,大气降尘和交通排放是主要贡献因子。结论]9种常见绿化树种叶片滞尘能力以夹竹桃、海桐和紫薇较强;叶片重金属元素积累能力以紫薇、金边黄杨和红花檵木较强,而夹竹桃、小蜡树和红叶石楠较弱。根据城镇功能区特点,选用滞尘能力和重金属积累能力较强的绿化树种,合理配置乔灌木树种,能够有效改善城镇空气质量。

Analysis on the Dust Retention and Heavy Metal Absorption Ability of Leaves: A Case Study in Yuyao, Zhejiang Province

Objective] To measure the dust retention and heavy metal absorption ability of 9 common landscaping tree species in the industrial area of Simen Town of Zhejiang Province and to determine the differences among common landscaping trees in purifying air and improving the environment quality. Method] The foliar dust retention, the heavy metal content in leaves, and the correlation between the dust retention and metal content in leaves of 9 landscaping tree species grown in three functional areas (industrial area, commercial and traffic area, and the leisure and entertainment area) were investigated. Result] (1) The dust retention ability varied significantly among the 9 tree species grown in the same environment. Nerium indicum, Pittosporum tobira and Lagerstroemia indica showed better in dust retention than the other species. (2) The foliar dust retention and heavy metal content of the same tree species varied greatly among different functional areas. The dust quantity and heavy metal content in a unit area increased with the air dust in different functional area. (3) The heavy metals in foliar dust had high homology in each functional area, suggesting that the atmospheric dust and traffic emissions are the main source of heavy metals. Conclusion] This study provides some useful information on the selection of landscaping tree species for improving the urban air quality.