Photochemical Transformations of Pollutants: Nitropyrene

污染物的光化学转化：硝基芘

• 批准号: 6766325
• 负责人: RAFAEL ARCE
• 金额: $ 7.65万
• 依托单位: UNIVERSITY OF PUERTO RICO RIO PIEDRAS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6766325
• 关键词: adsorption; aerosols; air pollution; biotransformation; carcinogens; chemical property; electron spin resonance spectroscopy; hazardous substances; intermolecular interaction; laser spectrometry; mutagens; nitrogen compounds; particle; photochemistry; physical property; pyrenes; solvents

1-Nitropyrene, a well known mutagenic and highly possible carcinogenic polycyclic aromatic hydrocarbon (PAH), is the most abundant nitrated PAH emitted in diesel engine exhaust and also found in coal combustion fly ash, cooked meat products and kerosene heaters emissions. It has been found at concentrations in the pg/m3 range in the air over urban and suburban areas and thus it has potential for human exposure through inhalation. The transformations in the atmosphere of these ubiquitous pollutants is still debated and a possible environmental fate for nitroPAHs is through their photodecomposition on particulate matter. Although some photodegradation rates and products have been determined in solution studies no reactive intermediates have been characterized to support the proposed mechanisms. Similar studies on these molecules adsorbed on substrates, which resemble their state on the environment, have been much more limited. In this work we are proposing to utilize techniques, we have already developed in our laboratory, to study the photochemical transformation mechanisms of nitropyrenes adsorbed into models of atmospheric aerosols in order to provide some understanding of the fate of these contaminants in the atmosphere. As we have found with PAHs, 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. In order to understand the phototransformation mechanism of adsorbed nitropyrenes we will: (1) examine the interactions of the adsorbed molecules with the different substrates and establish the nature of the participating excited states by absorption and fluorescence techniques, (2) determine relative photodegradation rates, (3) identify intermediate species and triplet states by time resolved diffuse reflectance laser spectroscopy and electron spin resonance and (4) identify the stable products and compare them with those found in the solution photochemistry. A fundamental aim of this proposal is to study the effect of some chemical and physical properties of the adsorbent such as composition, water content, presence of coadsorbed gases, average pore diameter and surface coverage on the photophysical and photochemical processes of the adsorbed nitropyrenes. Also, the resulting excited states and reactive intermediates from the laser irradiation in polar and non polar solvents that mimic the aerosol will be characterized by laser flash transient spectroscopy. The accomplishment of this last aim is of most importance since nitroPAHs can be also found in the organic liquid like-core of combustion aerosols.

1-硝基芘是一种众所周知的致突变性和高度致癌的多环芳烃（PAH），是柴油机尾气中含量最多的硝化多环芳烃，在燃煤飞灰、熟肉制品和煤油加热器排放物中也有发现。在城市和郊区的空气中发现它的浓度在pg/m3范围内，因此人类有可能通过吸入接触到它。这些无处不在的污染物在大气中的转变仍然存在争议，并且可能造成环境污染