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INFAMOS - a new method for speciated peroxy radical detection

INFAMOS - 一种检测形态过氧自由基的新方法

基本信息

批准号：
NE/M016439/1
负责人：
Grant Ritchie
金额：
$ 46.74万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FM016439%2F1
关键词：
INFAMOS new method speciated peroxy

项目摘要

The international societal response to deteriorating air quality and the changing climate is guided by the predictions of numerical models. These models contain estimates of future emissions of trace gases and aerosols from natural processes and human activities, their dispersal throughout the atmosphere, and their chemical transformations into a wide range of secondary products.Photo-oxidation in the troposphere is highly complex, being initiated by short lived radical species, in the daytime dominated by the hydroxyl radical, with contributions from chlorine atoms, and at night by either the nitrate radical or ozone. Fast chemical oxidation cycles remove trace species which are harmful to humans and to the wider environment. Many secondary products produced by atmospheric photo-oxidation are also directly harmful, for example ozone, nitrogen dioxide, acids and multifunctional organic molecules, many of which are of low volatility and are able to partition effectively to the condensed phase, creating secondary organic aerosol, with associated impacts on climate and human health. One of the best ways to test the accuracy of a chemical mechanism used in an air quality or climate model is to compare its calculated output for radical species for a given location and time with actual measurements made in the atmosphere. Radicals are ideal for this purpose as their lifetimes are short, and hence are controlled by chemistry rather than by transport.Two of the simplest radicals in the atmosphere are the hydroperoxy radical, HO2, and the smallest and dominant organic peroxy radical, CH3O2, which are formed directly by the reactions of OH with carbon monoxide and methane. Their reaction with nitric oxide constitutes the only tropospheric in situ source of O3, a respiratory irritant and a greenhouse gas. Despite their importance, neither HO2 nor CH3O2 are measured directly in the atmosphere, with HO2 only being determined indirectly following conversion first to OH after sampling.This proposal brings together leading expertise from a field measurement group at Leeds and a cavity enhanced optical spectroscopy group at Oxford to tackle this gap. The overarching aim is to develop a novel and direct laser spectroscopic technique called INFAMOS which has the potential to measure the concentrations of HO2 and CH3O2 in the field. An intercomparison of INFAMOS with complementary, but indirect, chemical conversion methods will be carried out in the Leeds HIRAC atmospheric chamber (volume 2250 litres), whose capabilities will also be improved via this proposal. The new technique will also be used to make direct, sensitive measurements of HO2 and CH3O2 in HIRAC to study the kinetics and product yields for several key atmospheric reactions which are poorly quantified, in conjunction with rate theory calculations and box modelling using the Master Chemical Mechanism.The newly developed technique to measure HO2 or CH3O2 will also have potential benefits in other areas, for example to understand fundamentals of combustion chemistry in the energy sector.

国际社会对空气质量恶化和气候变化的反应是由数值模型的预测指导的。这些模型包含了对未来自然过程和人类活动产生的痕量气体和气溶胶的排放、它们在大气中的扩散以及它们转化为各种次级产品的化学变化的估计。对流层中的光氧化是非常复杂的，由短寿命的自由基物种引发，白天主要是羟基自由基，氯原子也有贡献，而在晚上则是硝酸根或臭氧。快速的化学氧化循环可以去除对人类和更广泛的环境有害的痕量物质。大气光氧化产生的许多次级产品也是直接有害的，例如臭氧、二氧化氮、酸和多功能有机分子，其中许多具有低挥发性，能够有效地分配到凝聚相，产生次级有机气溶胶，对气候和人类健康产生相关影响。测试空气质量或气候模型中使用的化学机制的准确性的最佳方法之一是将其在给定位置和时间的自由基物种的计算输出与在大气中进行的实际测量进行比较。自由基是理想的，因为它们的寿命很短，因此是由化学控制的，而不是由传输控制的。在大气中最简单的两种自由基是氢过氧自由基，HO 2，和最小和最主要的有机过氧自由基，CH 3O 2，它们直接由OH与一氧化碳和甲烷反应形成。它们与一氧化氮的反应构成了对流层中唯一的O3原位来源，O3是一种呼吸刺激物和温室气体。尽管他们的重要性，无论是HO2或CH3O2是直接在大气中测量，与HO2只被间接确定后转换为OH采样后，第一次。这项建议汇集了领先的专业知识，从现场测量组在利兹和腔增强光谱组在牛津大学，以解决这一差距。总体目标是开发一种新的和直接的激光光谱技术，称为INFAMOS，它有可能在现场测量HO2和CH3O2的浓度。将在利兹HIRAC大气室（容积为2250升）中对INFAMOS与互补的、但间接的化学转化方法进行相互比较，该大气室的能力也将通过该提案得到提高。新技术还将用于对HIRAC中的HO 2和CH 3O 2进行直接、灵敏的测量，以研究几个关键的大气反应的动力学和产物产率，这些反应缺乏量化，结合速率理论计算和使用主化学机理的箱模型。新开发的测量HO 2或CH 3O 2的技术也将在其他领域具有潜在的好处，例如理解能源部门中燃烧化学的基本原理。