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| IN-SITU SPECIATION OF AEROSOL ORGANIC MATTER USING CHEMICAL IONIZATION MASS SPECTROMETRY | |
| 项目编号 | NNX07AN72H |
| JOEL THORNTON | |
| 开始日期 | 2007-09-01 |
| 结束日期 | 2010-08-31 |
| 英文摘要 | The objective of this project is to investigate two major revisions to our current conceptual model for organic aerosols: (i) gas-particle partitioning of primary organic aerosol (POA) emissions and significant evaporation of POA at ambient conditions; (ii) photochemical aging of low-volatility organic vapors as an important source of secondary organic aerosols (SOA).Our approach relies heavily on the “basis set” framework developed at Carnegie Mellon University. The basis set lumps low-volatility organics into a set of “volatility bins” according to their vapor pressures, thereby representing the volatility distribution of the mixture. The volatility basis set, in conjunction with absorptive partitioning theory, is an efficient means for tracking gas-particle partitioning of all organics in CTMs. It also allows for multiple generations of SOA chemistry. Using dilution samplers and a smog chamber, we propose experiments to measure the effects of dilution and temperature on the gas-particle partitioning of organic aerosol from three key source classes: diesel exhaust, gasoline exhaust (with and without a catalytic converter), and wood smoke. These data will be fit using partitioning theory to determine the volatility distribution of the emissions from each source. Smog chamber experiments will be conducted to measure the SOA produced from photo-oxidation of diluted exhaust from each source across a range of atmospheric conditions. In the basis-set framework, the effects of photochemical aging are represented using a transformation matrix that maps more volatile reactant species into lower volatility bins as they undergo oxidation. This matrix will be derived from the chamber data, providing an empirical description of how the initial volatility distribution of the emissions evolves in order to match the SOA produced in the experiments. Finally, results from the experiments will be use to develop a module for CTMs such as PMCAMx and CMAQ to represent gas-particle partitioning and photochemical aging of primary emissions. This module will be implemented in PMCAMx and simulations will be performed to investigate the effects of our proposed revisions on urban and regional air quality and to evaluate model performance.Expected results from this research include detailed characterization of emissions and gas-particle partitioning of low-volatility organics emitted by the target sources; smog chamber quantification of SOA production from photochemical oxidation of diluted exhaust across a range of atmospheric conditions for each source; development of a CTM module for gas-particle partitioning and photochemical aging of primary emissions; CTM simulations assessing the impacts of these processes on urban and regional OA levels in different seasons; and a detailed evaluation of model predictions using ambient data. |
| 英文关键词 | particulates;organics;primary sources;air quality modeling;emissions characterization;environmental chemistry;engineering;measurement methods;ambient air;atmosphere;mobile sources;absorption;chemical transport;tropospheric, |
| 学科分类 | 11 - 工程与技术;1107 - 航空航天工程;03 - 天文学 |
| 资助机构 | US-NASA |
| 国家 | US |
| 语种 | 英语 |
| 文献类型 | 项目 |
| 条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/76734 |
| 推荐引用方式 GB/T 7714 | JOEL THORNTON.IN-SITU SPECIATION OF AEROSOL ORGANIC MATTER USING CHEMICAL IONIZATION MASS SPECTROMETRY.2007. |
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