一种计算生态风险的新方法北京大学教务部.doc

PAGE  PAGE 9 北京大学及其周边地区非取暖期植物叶片中的多环芳烃 环境学院00级 王雅琴 摘 要 采集了北京大学校园内及周边交通干线附近六种植物叶片样品，分别测定了叶腊和叶组织中的多环芳烃含量，同步测定了叶腊、叶脂、气孔密度等参数，藉以探讨机动车尾气排放对植物叶腊和叶组织中多环芳烃含量的影响。结果证实：交通干线附近样品叶腊和叶组织中多环芳烃含量显著高于校园对照。叶腊中多环芳烃含量较叶组织高1－2个量级。叶腊和叶组织中16种多环芳烃化合物分布谱相似，但高环化合物更多在叶腊中聚集，而低环多环芳烃在叶组织中占优。叶腊多环芳烃含量与单位叶面积中的叶腊含量成反比，叶组织多环芳烃含量与气孔密度成反比，但其关系确定需要进一步实验证实。 关键词：多环芳烃；大气；叶；叶面吸收 Polycyclic aromatic hydrocarbons in plant leaves from Peking University campus and nearby in summer season College of Environmental Sciences Grade2000 Wang Yaqing Abstract Leaves of 6 plants were colleted from two sites on and around Peking University campus in summer season of 2003. PAHs in the leaf-wax and tissues were determined together with leaf-was content, tissue lipid, specific surface, and stomata density. The results were compared to investigate the possible sources of PAHs in the leaves. For both leaf-wax and tissue samples, levels of PAHs were plant species dependent and were higher in the samples from campus than those from outside of campus in short distance to busy traffic, suggesting a significant influence of vehicle emission. The concentrations of PAHs in leaf-wax were 1-2 orders of magnitude higher than those in leaf tissues. While the PAH profiles in the leaf-wax and leaf tissues were similar in general, the relative contents of volatile compounds were higher in the tissues than in the wax. Negative correlations were identified between PAHs concentration in the leaf-wax and the wax content and between the tissue PAH content and stomata density. Keyword: PAHs, foliar uptake, leaf, ambient air 多环芳烃 (Polycyclic Aromatic Hydrocarbons，PAHs)，是广泛分布于全球环境中的微量有毒有机污染物。其毒性主要体现在对生物体的强烈致癌致畸变作用[1]，是近年来国际国内环境科学研究领域中的持续热点???一。PAHs有自然和人为两种来源，其中人为源包括钢铁和石油工业生产中的排放以及化石燃料的不完全燃烧。就城市非工业区室外环境而言，供暖燃煤和机动车燃油中释放构成了大气PAHs的最重要来源。例如，朱利中等分析了杭州市空气中PAHs污染与城市交通的相关性，认为该城市空气中的PAHs主要源于汽车尾气的排放[2]。Miguel等以Caldecott公路隧道为例，研究了10种PAHs的浓度与车型和流量的定量关系[3]。 由于不同多环芳烃化合物的挥发性不同，PAHs在大气中的赋存形态和相互转化特征有很大差别。一般条件下，2-3环化合物以气态为主要存在形式，4环化合物气-颗粒间分配相对均衡，而5环以上化合物主要