Characterization of Urban Grime Photochemistry as Sink or Source for Air Pollutants(GrimePaSS)

欧洲城市空气质量的改善是一个主要问题，这增强了人们对了解最相关的空气污染物，如氮氧化物(NOx)、臭氧(O3)和几种挥发性有机化合物(VOCs)的化学过程和途径的兴趣。除了气相化学，当气体与城市表面(如窗户、建筑墙壁、屋顶、人行道、道路等)相互作用时，也会发生多相和多相反应。这些过程可能会影响空气污染物的命运。当这些表面暴露在大气中一段时间后，就会形成一种由无机和有机成分组成的所谓的城市污垢薄膜。然而，关于这种新的环境隔间在光照下与空气污染物的相互作用的知识仍然局限于少数几个单独的研究。因此，拟议的项目将结合真实的城市污垢采样与实验室和模型研究，以表征城市污垢在不透水表面的光反应行为。将进行小型实验室规模的光反应器和气雾室实验，以调查城市污垢是否潜在地充当空气污染物的汇或源。这一实验方法将首次提供有关动力学(吸收系数、沉积速度等)的全面数据。对于不同的空气污染物(例如，NOx、臭氧、甲苯)，将提供对反应机理和潜在的二次产物形成的洞察。在这些光活性实验前后，通过CPP-GC-MS和离子色谱对城市污垢化学成分的额外分析，将把结果扩展到多相化学数据集，该数据集将进一步应用于模拟模块。该模型最终将对与城市灰尘有关的空气污染物的总体寿命和命运提供有用的见解。总的来说，拟议的项目将首次全面回答城市灰尘作为城市地区一个新的环境分区将如何影响空气质量和相关的健康影响的问题。

The improvement of urban air quality in Europe is a major concern that strengthens the interest in understanding the most relevant chemical processes and pathways of air pollutants, like nitrogen oxides (NOx), ozone (O3) and several volatile organic compounds (VOCs). Besides gas phase chemistry, also heterogeneous and multiphase reactions when gases interact with urban surfaces (e.g., windows, building walls, rooftops, sidewalks, roads, etc.) are processes which could affect the fate of air pollutants. When such surfaces are exposed to the atmosphere for a certain time, it is known that a so called “urban grime” film consisting of inorganic and organic components will develop. However, the knowledge about the interaction of this new environmental compartment with air pollutants under illumination is still limited to a handful individual studies.The proposed project, therefore, will combine real urban grime sampling with laboratory and modelling studies to characterize the photoreactive behavior of urban grime at impervious surfaces. Small lab scale photoreactor and aerosol chamber experiments will be performed to investigate whether urban grime is potentially acting as a sink or a source for air pollutants. This experimental approach will provide for the first time comprehensive data on the kinetics (uptake coefficients, deposition velocities, etc.) for different air pollutants (e.g., NOx, O3, toluene) and will give insights into reaction mechanisms and potential secondary product formation. The additional analysis of the urban grime chemical composition by CPP-GC-MS and ion chromatography before and after these photoreactivity experiments will extend the results to a multiphase chemical data set which will further be applied in a modelling module. The modelling will finally provide useful insights into the overall lifetimes and fates of air pollutants associated with urban grime.Overall, the proposed project will give for the first time a comprehensive answer to the question how urban grime as a new environmental compartment in urban areas will impact air quality and associated health effects.