不同PM2.5污染区常见树种叶片对PAHs的吸收特征分析
Absorption features of PAHs in leaves of common tree species at different PM2.5 polluted places
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摘要: 采集了北京市奥林匹克森林公园和西直门北大街2个不同PM2.5污染区的6种植物叶片样品,应用高效液相色谱法测定叶片中多环芳烃(PAHs)的含量,比较6种常见树种叶片对PAHs的吸收特征,并对PAHs的成分具体分析。结果表明:不同树种吸收PAHs的能力有差异。在2个采样点,圆柏、油松针叶树种叶片对PAHs的吸收含量均高于阔叶树种;阔叶树种中碧桃叶片对PAHs的吸收含量最高,其次是毛白扬。此外,随着污染的加重,树种能够增强其吸收PAHs的能力以适应环境污染。6种树种叶片对PAHs的吸收含量均表现为污染较重的西直门高于污染较轻的森林公园。对6种树种叶片的PAHs成分分析表明,叶片中PAHs的主要成分为3环化合物,其次是2环、4环和5~6环化合物,叶片对不同环数化合物的吸收含量也表现为西直门高于森林公园。西直门样品中3环化合物的组分略多于森林公园样品,且组分的含量也高于森林公园样品。6种树种叶片对PAHs吸收含量的主成分分析指出,树种吸收PAHs能力大小依次为圆柏碧桃油松毛白杨榆树紫叶李。Abstract: Leaves of six tree species were collected from two sites with different atmospheric PM2.5 levels in Beijing, i.e., the National Olympic Forest Park and Xizhimen traffic hub. The components and concentrations of PAHs absorbed were measured using high performance liquid chromatography, and were compared among the six tree species. The relationship between leaf PAHs concentration and atmospheric PM2.5 level was preliminarily investigated. The results showed that PAHs contents in the leaves of coniferous trees such as Sabina chinensis and Pinus tabuliformis were higher than those of broadleaf trees. The content of PAHs in Amygdalus persica was the highest, followed by Populus tomentosa. In addition, as the pollution was aggravating, tree species could enhance the ability to absorb PAHs to adapt to the environmental pollution. For all the six tree species, PAHs contents in leaves sampled from the Xizhimen traffic hub with higher PM2.5 level were higher than those from the National Olympic Forest Park. Three-ring compounds were the major component in leaf-absorbed PAHs, followed by two-ring, four-ring and five- or six-ring compounds. The contents of compounds with different ring numbers in the leaf samples from Xizhimen traffic hub were higher than those from National Olympic Forest Park. Both three-ring compounds and contents in the leaf samples from Xizhimen traffic hub were higher than those from National Olympic Forest Park. A principal component analysis based on the contents of different PAHs components suggested that the ability of the species to absorb PAHs followed the order of Sabina chinensisAmygdalus persicaPinus tabuliformisPopulus tomentosaUlmus pumilaPrunus cerasifera.