Photodegradation Reactions Mono and Dinitro PAHs

单硝基多环芳烃和二硝基多环芳烃光降解反应

• 批准号: 7676086
• 负责人: RAFAEL ARCE
• 金额: $ 25.64万
• 依托单位: UNIVERSITY OF PUERTO RICO RIO PIEDRAS
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7676086
• 关键词: 1-Nitropyrene; 2,4-Dinitrophenol; Aerosols; Affect; Air; Air Pollutants; Air Pollution; Area; Aromatic Polycyclic Hydrocarbons; Automobile Exhaust; Benzo(a)pyrene; Biological Assay; Breathing; Caliber; Carbon; Cardiopulmonary; Cardiovascular system; Chemicals; Classification; Coal; Complex; DNA Sequence Rearrangement; Data; Death Rate; Diesel Exhaust; Dissociation; Environment; Environmental Exposure; Environmental Health; Environmental Risk Factor; Evaluation; Excision; Exposure to; Film; Gases; Genetic Recombination; Goals; Health; Human; Hydrogen; Inorganic Sulfates; Kinetics; Knowledge; Laboratories; Lasers; Link; Liquid substance; Lung; Malignant neoplasm of lung; Mechanics; Modeling; Mono-S; Motor Vehicles; Movement; Nature; Nitrites; Oxides; Oxygen; Parents; Particulate; Particulate Matter; Photochemistry; Power Plants; Process; Property; Reaction; Relative (related person); Reporting; Research; Research Personnel; Risk; Risk Assessment; Route; Salts; Smoke; Solid; Solutions; Solvents; Source; Structure; Surface; Surface Properties; System; Techniques; Temperature; Testing; Time; Toxic effect; Triplet Multiple Birth; Unspecified or Sulfate Ion Sulfates; Water; Wood material; Work; base; chemical property; design; fly ash; irradiation; mortality; particle; physical property; physical state; planetary Atmosphere; pollutant; quantum; residence; respiratory; triplet state

DESCRIPTION (provided by applicant): Particulate matter (PM2.5) has been linked to a range of serious respiratory and cardiovascular health problems. The nitroPAHs found in the (PM2.5) are formed during combustion processes or by either chemical or photochemical reactions of polycyclic aromatic hydrocarbon in polluted atmospheres. NitroPAHs have been identified in extracts of respirable particles collected from polluted urban air, diesel exhaust particles, automobile exhaust, coal fly ash and wood smoke. The nitroPAHs are typically less abundant in ambient air than PAHs and are found at concentrations in the range of pg/m3 to ng/m3. Nonetheless, some of them could be more mutagenic or carcinogenic in laboratory bioassays than the parent PAH. Thus, it is of great significance to understand their sources and transformations in the atmosphere in assessing environmental exposure and risks. Specifically, their transformations at the solid/air interface or in the liquid-like environment of the organic fraction of the combustion derived aerosols can have a significant impact on controlling their residence time in the environment. It is important to study the photochemistry in these two environments because their photodegradation can proceed by entirely different mechanisms depending on the reaction medium. We are proposing to utilize techniques, already developed in our laboratory, to study the photochemical transformation mechanisms of nitroPAHs adsorbed or absorbed into models of atmospheric particulate matter in order to provide some understanding of the fate of these contaminants in the atmosphere. As we have found with PAHs, that phototransformations at the solid/air interface can have a significant impact in controlling their residence time in the environment, and are thus important in the evaluation of the potential risks of these contaminants, as well as in the possible design of systems for their removal. The working hypothesis is that the physical and chemical properties of the particulate matter are determining factors in the reactivity of the excited states and intermediates participating in the photochemical transformations of these pollutants in that environment. In order to understand the phototransformation mechanism of adsorbed or absorbed nitroPAHs we will: (1) isolate/and characterize the principal stable photoproducts and determine their quantum yields and the effect of the nature of the solvent (polar, non polar, polar aprotic, hydrogen abstraction easiness), and of organic compounds found in the atmospheric aerosols on the product yields, (2) isolate and characterize the principal stable photoproducts produced on adsorbents that mimic the atmospheric particle matter such as inorganic oxides, and sulfate salts, and determine the effect of the physical and chemical properties of the surfaces of these solids (such as composition average pore diameter, surface coverage) on the products relative yields, and to compare their relative yields and distribution with those obtained in the different solvents. The effect of coadsorbed water and oxygen on the yields will also be examined and (3) identify and characterize the participating excited states and reactive intermediates in the phototransformation process occurring in solution and on the surfaces. Related to this aim is the determination of the effect of organic cosolutes encountered in the atmospheric aerosol on the reaction kinetics of the intermediates. The physical properties of the participating excited states and reactive intermediates will be supported by quantum mechanical calculations.

描述(申请人提供)：颗粒物(PM2.5)与一系列严重的呼吸系统和心血管健康问题有关。在PM2.5中发现的硝基多环芳烃是在燃烧过程中形成的，或者是多环芳烃在污染的大气中发生化学反应或光化学反应形成的。从受污染的城市空气、柴油尾气、汽车尾气、飞灰和木烟中收集的可吸入颗粒物的萃取物中已发现硝基多环芳烃。硝基多环芳烃在环境空气中的含量通常低于多环芳烃，其浓度范围在pg/m~3至ng/m~3之间。尽管如此，在实验室生物检测中，它们中的一些可能比母体多环芳烃具有更强的诱变性或致癌性。因此，了解它们在大气中的来源和转化对于评估环境暴露和风险具有重要意义。具体地说，它们在固体/空气界面或在燃烧产生的气溶胶的有机部分的类液体环境中的转化对控制它们在环境中的停留时间有重大影响。研究这两种环境中的光化学非常重要，因为它们的光降解可以通过完全不同的机制进行，具体取决于反应介质。 我们建议利用实验室已经开发的技术，研究被吸附或吸收到大气颗粒物模型中的硝基多环芳烃的光化学转化机制，以便对这些污染物在大气中的去向提供一些了解。正如我们对多环芳烃所发现的那样，固体/空气界面上的光转化对控制它们在环境中的停留时间具有重大影响，因此在评估这些污染物的潜在风险以及可能的系统设计中都很重要。工作假设是，颗粒物的物理和化学性质是在该环境中参与这些污染物的光化学转化的激发态和中间体的反应性的决定因素。为了了解吸附或吸附的硝基多环芳烃的光转化机理，我们将：(1)分离和表征主要的稳定光产物，并确定它们的量子产率以及溶剂的性质(极性、非极性、非质子、易抽氢)和大气气溶胶中有机化合物的性质对产物产率的影响；(2)分离和表征在模拟大气颗粒物的吸附剂(如无机氧化物和硫酸盐)上产生的主要稳定光产物，并确定这些固体表面的物理和化学性质(如组成、平均孔径、表面覆盖度)对产物相对产率的影响。并将其相对产率和分布与在不同溶剂中得到的结果进行比较。还将考察共吸附的水和氧对产率的影响，以及(3)识别和表征在溶液中和表面发生的光转化过程中的参与激发态和活性中间体。与这一目标相关的是确定大气气溶胶中遇到的有机共溶体对中间体反应动力学的影响。参与激发态和反应中间体的物理性质将通过量子力学计算得到支持。