Nitrous Acid Chemistry in the Troposphere

9615748周这项计划旨在加深我们对对流层亚硝酸化学的了解，包括它的分布、形成机制、作为羟基自由基源的重要性，以及在城市和清洁环境中作为氮氧化物循环途径的重要性。这些知识，当被纳入模型时，将提高我们预测氧化剂的光形成，如羟基自由基和臭氧的能力，以及在区域或全球范围内污染物的光降解。在城市环境中的实地测量已经证实，HONO光解是上午几个小时内羟基的主要来源。然而，由于缺乏灵敏的方法，在清洁气团中进行的HONO测量很少。因此，HONO的分布及其作为羟基前体的重要性还知之甚少。尽管人们认识到大气中的HONO是通过NOx和硝酸的非均相反应形成的，但HONO的确切生成机理尚未得到很好的描述。在这个项目中，将开发一种高灵敏度的HONO大气测量技术。它将基于使用线圈取样器对HONO进行水洗，然后用2，4-二硝基苯肼衍生化，并使用高效液相色谱-紫外检测来测定形成的叠氮化物。该技术的检测下限将小于1pptv，时间分辨率为10分钟。这项技术将用于在纽约州奥尔巴尼市中心进行为期两周的四次密集测量和在纽约州怀特法斯山顶峰进行为期一个月的密集活动期间，建立HONO的分布以及污染和清洁空气团中的一套化学和气象参数。将建立一个盒子模式，通过比较预测的HONO分布和测量的HONO分布来验证所提出的形成机制，并获得关于HONO在对流层化学中的重要性的信息。***

9615748 Zhou This project aims to advance our understanding of the chemistry of nitrous acid (HONO) in the troposphere, including its distribution, its formation mechanisms, and its importance as a source for hydroxyl radicals, and as a recycling pathway for NOx in both urban and clean environments. This knowledge, when incorporated into models, will improve our ability to predict the photoformation of oxidants, such as hydroxyl radicals and ozone, and photodegradation of pollutants on a regional or global scale. Field measurements in urban environments have confirmed that HONO photolysis is a major source for hydroxyl during the morning hours. However, few HONO measurements have been made in clean air masses, due to a lack of sensitive methods. Therefore, the HONO distribution and its importance as a hydroxyl precursor is poorly understood. The exact formation mechanisms of HONO are not well characterized, although it is recognized that atmospheric HONO is formed via heterogeneous reactions involving NOx and nitric acid. In this project, a highly sensitive technique for atmospheric measurements of HONO will be developed. It will be based on aqueous scrubbing of HONO using a coil sampler, followed by derivatization with 2,4-dinitrophenylhydrazine and determination of the azide formed using HPLC with UV-detection. The detection limit of this technique will be less than 1 pptv with a time resolution of ten minutes. This technique will be used to establish the distribution of HONO along with a suite of chemical and meteorological parameters in both polluted and clean air masses, during four two-week intensive measurements in downtown Albany, NY, and one one-month intensive campaign at the summit of Whiteface Mountain, NY. A box model will be constructed and used to verify suggested formation mechanisms by comparing the predicted and measured HONO distributions, and to obtain information on the importance of HONO in tropospheric chemistry. ***