Investigation of PAH Photodegradation in Solutions

描述（由申请人提供）：多环芳烃（PAH）是自然界中普遍存在的致癌和致突变污染物。人类活动，包括化石燃料的燃烧，有助于这些化合物在环境中的总丰度。吸附在细颗粒物上的半挥发性多环芳烃通过吸入进入人体。了解多环芳烃释放到环境中后的命运是一个公共卫生问题。太阳光诱导的光氧化是去除环境中多环芳烃的重要方法。拟议的研究旨在测量光化学速率常数和产物量子产率，以预测包括大气颗粒，水和其他环境表面在内的凝聚相系统中PAH衰变的速率。与以往的研究不同，本研究的结果可用于识别和量化当地环境中的PAH光氧化产物。这是重要的信息，因为多环芳烃光氧化产物不仅比多环芳烃和另一组可疑的致癌物更具反应性，而且它们在水系统中也更易溶解，因此可以在更长的距离内运输。 拟议的工作的假设是，主要通过自由基阳离子介导的机制降解的多环芳烃将有降解速率，这是依赖于它们所居住的介质中的电子供体的能力，将有一个多样性的特征和以前未识别的光产物在这些过程中创建。为了验证这一假设，本论文提出了三个具体的研究目标：（1）利用结构灵敏的HPLC/MS/MS技术表征多环芳烃光降解的光产物：（2）测量不同极性溶液中所观察到的光产物的生成速率和量子产率，以阐明电子供体对环境中多环芳烃光降解速率的作用;（3）操纵光解过程中的特定机制中间体，以阐明具有一系列电子清除电位的基质中PAH光解的主导机制。 拟议的工作将使用最近开发的LC/MS/MS技术来测量PAH光氧化的产物量子产率的解决方案具有特殊的灵敏度和选择性相对于其他分析技术。该项目的成功将有助于阐明环境对颗粒吸入的破坏性影响的作用。该研究还将提供模拟环境多环芳烃光降解所需的动力学参数，激发从污染场地清除的想法。

DESCRIPTION (provided by applicant): Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutanogenic pollutants ubiquitous in the natural world. Human activities, including the combustion of fossil fuels, contribute to the total abundance of these compounds in the environment. Semi-volatile PAHs adsorbed to fine particulate matter enter the body via inhalation. It is a matter of public health to understand the fate of PAHs after they are released into the environment. Sunlight-induced photooxidation is an important method of PAH removal from the environment. The proposed research is designed to measure photochemical rate constants and product quantum yields necessary to predict the rates of PAH decay in condensed phase systems including atmospheric particles, water, and other environmental surfaces. Unlike previous studies, the results of this study can be used to identify and quantify PAH photooxidation products in local environments. This is important information because PAH photooxidation products are not only more reactive than PAHs and another group of suspected carcinogens, but they are also more soluble in aqueous systems and consequently can be transported over longer distances. The hypothesis of the proposed work is that PAHs that degrade predominately via the radical-cation mediated mechanism will have degradation rates that are dependent on the electron-donor capacity of the media in which they reside, and there will be a diversity of under-characterized and previously unidentified photoproducts created in these processes. To explore this hypothesis, three specific objectives for the proposed research have been formulated: (1) Characterize photoproducts of PAH photodegradation using structurally sensitive HPLC/MS/MS techniques; (2) Measure formation rates and quantum yields of the observed photoproducts in solutions with varied polarity to elucidate the role of electron donors on the rates of PAH photodegradation in the environment; (3) Manipulate mechanism-specific intermediates during photolysis to elucidate the dominant mechanism for PAH photodegradation in matrices with a range of electron-scavenging potentials. The proposed work will use recently developed LC/MS/MS techniques to measure the product quantum yields of PAH photooxidation in solutions with exceptional sensitivity and selectivity relative to other analytical techniques. The success of this project will help to elucidate the role of the environment on the damaging effects of particle inhalation. The study will also provide kinetic parameters necessary to model the photodegradation of environmental PAHs, inspiring ideas for removal from contaminated sites.