Nitrous Acid Chemistry in the Troposphere

对流层中的亚硝酸化学

• 批准号: 9615748
• 负责人: Xianliang Zhou
• 金额: $ 29.87万
• 依托单位: Health Research Incorporated/New York State Department of Health
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-01 至 2001-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9615748&HistoricalAwards=false
• 关键词: Nitrous; Acid; Chemistry; Troposphere

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. ***

本项目旨在加深我们对对流层中亚硝酸（HONO）化学性质的理解，包括其分布、形成机制、作为羟基自由基来源的重要性，以及在城市和清洁环境中作为氮氧化物回收途径的重要性。当将这些知识纳入模型时，将提高我们预测氧化剂（如羟基自由基和臭氧）的光形成以及区域或全球范围内污染物的光降解的能力。在城市环境中的实地测量证实，HONO光解是上午羟基的主要来源。然而，由于缺乏敏感的方法，很少在清洁空气团中进行HONO测量。因此，人们对HONO的分布及其作为羟基前体的重要性了解甚少。虽然大气中的HONO是通过涉及NOx和硝酸的非均相反应形成的，但其确切的形成机制尚不清楚。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进行水擦洗，然后与2,4-二硝基苯肼衍生化，并使用紫外检测的高效液相色谱法测定形成的叠氮化物。该技术的检测限小于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密集测量，并在纽约州怀特法斯山山顶进行为期一个月的密集活动，以确定HONO的分布以及一套化学和气象参数。通过比较预测和实测的HONO分布，将构建一个箱形模型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。＊＊＊