城市化地区大气卤代多环芳烃来源与人群呼吸暴露研究

Halogenated polycyclic aromatic hydrocarbons are a kind of emerging organic pollutant with dioxin-like toxic effects. These compounds generally have close relationship with urban development phases. For these reasons, they have intrigued environmental scientists interests in recent years. However, there is no report regarding to source and human inhalation exposure of halogenated polycyclic aromatic hydrocarbons has been published so far. This proposed project, selecting Shenzhen (a typical representation of rapid urbanization) as the study zone and adopting a combined approach of field sampling and analysis, laboratory simulation and numerical modeling, will investigate the sources and human health hazards of halogenated polycyclic aromatic hydrocarbons, with the intention to enhance the current knowledge about the environmental behaviors and human exposure of target pollutants. The specific objectives of the proposed study are to examine the emission factors of the target contaminants, assess the human exposure by local population to the target pollutants via ingestion and inhalation, and assess related human health impact. This proposed project is expected to achieve some original results in the areas of development of regional emission inventories, uncertainty analysis in human exposure modeling, bioavailability in human gastrointestinal tract, and human health hazards due to multi-path intake. These results not only could further understanding of the regional processes of the target pollutants from source to effect generation, but also would provide the policy makers with sound scientific data for decision making.

卤代多环芳烃属于毒性类似二恶英的新兴有机污染物，其来源与城市生活方式紧密关联，近年来开始受到环境科学家的关注。然而，关于城市大气中该类物质污染源特征及排放引发人群呼吸暴露的研究迄今未见报道。本项目拟以典型城市化代表的深圳为研究区域，通过环境样品分析、实验室模拟和数值模型等手段，研究城市大气中卤代多环芳烃污染源特征及其引发的呼吸暴露风险。阐明研究区域卤代多环芳烃的主要来源排放成份谱图，排放因子，排放通量等关键问题，同时研究气相吸入与颗粒相人体呼吸道沉降方式的人体呼吸暴露效应，结合申请人前期开展的该地区人群饮食暴露研究结果，综合考虑人群总体外暴露导致的健康风险。本项目具有突出的新颖性，有望在卤代多环芳烃区域排放因子、人体暴露风险分析方面取得创新性成果。相关成果不仅有助于认识城市卤代多环芳烃从产生到危害的过程，可以为城市化过程环境效应研究提供重要案例，而且可为相关部门制定控制对策提供科学依据。

机动车尾气和垃圾焚烧是城市大气中卤代多环芳烃（HPAH）及其母体（PAH）的主要来源。项目研究了垃圾焚烧、机动车尾气排放基本特征，同时对机动车尾气、垃圾焚烧排放HPAH和PAH未来趋势做了预测。..垃圾焚烧排放的高环多环芳烃主要富集于PM2.5 (66%-86%)，低环芳烃主要集中于PM10 (83%-86%)；气相中，低环芳烃占86% ~ 97%。ΣHPAH主要富集在粗颗粒(> 83%)。ΣPAH和ΣHPAH粒径分布都表现为双峰（9.0 -10 μm和4.7−5.8μm)。粗颗粒中卤代多环芳烃及其母体的富集意味着垃圾焚烧厂排放的颗粒结合态芳烃难于远距离迁移。模拟发现，空气中目标物浓度最大值的峰值出现在离焚烧炉约300 米处，随后急剧下降。城市垃圾焚烧厂对大气污染影响范围似乎非常大，但污染物水平极低，影响可以忽略。..模拟研究表明：在垃圾焚烧过程中，2-3环多环芳烃的排放因子高于4-6环多环芳烃。各个HPAHs的排放因子在所有焚烧产物中差别不大。Ʃ16PAH和Ʃ3ClPAH的排放因子的递减次序为；气相>底灰>粗颗粒>细颗粒；对Ʃ6BrPAH，该次序为底灰>气体>粗颗粒>细颗粒。Σ16PAH、Σ3ClPAH、Σ6BrPAH粒径分布呈现三峰的峰值。细颗粒在空气中的并聚可能导致粗颗粒组分中目标化合物的富集。气相和颗粒相目标物没有达到理论平衡，大部分目标物被有机碳锁定。比较发现，汽车尾气对城市空气污染的贡献要大于垃圾焚烧。..与交通有关的PAHs和HPAHs排放对城市空气的影响研究表明，颗粒相的PAHs和HPAHs排放量大于气相；颗粒相中目标物主要集中于在2.1 - -3.3 μm颗粒上，是颗粒相PAH和HPAH主要贡献者。与交通相关的多环芳烃排放贡献，仅占我国多环芳烃排放总量的3%左右，属于被高估的污染来源。与交通相关的污染物排放总量相比，源于机动车引擎的尾气排放的贡献很小。..基于排放特征研究结果，我们对垃圾焚烧和机动车尾气排放PAH和HPAH的人群呼吸暴露风险做了研究。例如，相对于运动场，路边跑步的致癌风险并未显著增加。