Total Ozone Reactivity: A new measurement of volatile organic compounds in the atmosphere

臭氧总反应性：大气中挥发性有机化合物的新测量方法

基本信息

批准号：
NE/P003524/1
负责人：
William Bloss
金额：
$ 15.96万
依托单位：
University of Birmingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FP003524%2F1
关键词：
Total Ozone Reactivity new measurement

项目摘要

Gaseous hydrocarbons - volatile organic compounds (VOCs) - are key atmospheric components. They may be air pollutants, harmful to human health in their own right, and some are greenhouse gases. Atmospheric chemical processing of VOCs leads to the formation of secondary pollutants such as ozone and secondary organic aerosol - which adversely affect health, damage vegetation (reducing crop yields by 5 - 15% globally) and affect climate. A quantitative understanding the atmospheric VOC budget underpins many aspects of atmospheric science.However, quantifying the VOC budget is a challenging goal, as very many atmospheric VOCs are emitted, each of which produces a cascade of degradation products - numbering over order-of-10^5 individual chemical species from larger VOCs. This is particularly the case for biogenic VOCs (BVOCs) which tend to be larger, more chemically complex molecules, and which dominate non-methane VOC emissions globally. Traditional approaches, in which individual species are measured, quickly run up against this barrier of chemical complexity and cannot assess the total VOC budget - consequently, we are unable to fully quantify the total potential for secondary pollutant formation from VOC oxidation.An alternative approach is to measure an integrated property of all VOCs present - such as their chemical reactivity, the rate at which a given atmospheric oxidant reacts with all VOCs present. This determines the reactive potential of all VOCs - both those identified and those unmeasured - providing a metric directly related to secondary pollutant formation. This approach has been successfully trialled for OH radicals, and measures of the OH reactivity have shown that attempting to measure each individual species by conventional approaches may underestimate the VOC budget by up to 90%. While OH radicals dominate oxidation of many VOCs during the day, for alkene species (such as the majority of biogenic VOCs) reaction with ozone is also important - dominant at night, and as important as OH during the day for the larger BVOCs, mono- and sesquiterpenes, which are the most challenging to measure with conventional approaches. Therefore, measurement of the total ozone reactivity has potential to provide new insight into the total budget of reactive BVOCs present in the atmosphere, and the extent to which it is currently substantially underestimated - a hypothesis attracting growing support from a range of recent measurements.Within this project, we will develop a prototype ozone reactivity instrument, building upon a feasibility study carried out in our laboratory; we will test the system performance with individual VOC standards, and with complex VOC mixtures from plant specimens in laboratory enclosures, and we will demonstrate its applicability to assess the change in BVOC emissions from whole trees in response to environmental stress. This latter objective will be achieved through measurements at the internationally unique whole tree chambers at the Hawkesbury Forest Experiment (HFE) site in Richmond, NSW, where we will measure changes in total ozone reactivity from eucalyptus trees as a function of changing RH, temperature and CO2 abundance (400 ppm [i.e. present day] vs 640 ppm). Within the duration of this project, only limited experiments may be undertaken - but these will provide a unique insight into the response of total BVOC emissions from vegetation to environmental change, underpinning future exploitation of the approach.Completion of the project will achieve technology readiness level (TRL) 4 - basic validation in a controlled environment. Following this proof-of-concept work (i.e. outside this proposal), we have identified an opportunity for initial field deployment of the technique, to perform the first measurements of total BVOC ozone reactivity in ambient air, from a mature Oak woodland under conditions of present day and anticipated future CO2 levels.

气态碳氢化合物 - 挥发性有机化合物（VOC）是关键的大气成分。它们可能是空气污染物，对人类健康有害，有些是温室气体。 VOC的大气化学加工会导致形成次要污染物，例如臭氧和二级有机气溶胶 - 对健康，损害植被（将农作物产量降低5-15％）并影响气候。大气VOC预算的定量了解是大气科学的许多方面。但是，量化VOC预算是一个艰巨的目标，因为发出了许多大气中的VOC，每种VOC都会产生一系列降级产品 - 与来自较大VOC的10^5个单独的化学物种相比，编号是来自较大VOC的单个化学物种。倾向于更大，化学更复杂的分子并且在全球范围内主导的非甲烷VOC发射的生物源性VOC（BVOC）尤其如此。传统的方法是测量各个物种的，迅速与这种化学复杂性的障碍相抵触，无法评估VOC总预算 - 因此，我们无法完全量化VOC氧化中二级污染物形成的总潜力。一种替代方法是衡量所有VOC的综合特性，例如，所有VOC的综合性能 - 例如，它们的化学反应性，其在给定的大气氧化剂中，与所有VOC的速率相对于所有vocs反应。这决定了所有VOC的反应性潜力 - 既可以识别出来又是未得到的，它们提供了与二级污染物形成直接相关的度量。这种方法已成功地试用了OH激进分子，OH反应性的测量表明，试图通过常规方法测量每个物种的方法可能会低估VOC预算高达90％。虽然OH自由基在白天占主导地位的许多VOC氧化，但对于烯烃物种（例如大多数生物VOC）与臭氧的反应也很重要 - 在夜间占主导地位，而在白天，对于较大的BVOC，单声道和曲苯甲酸酯而言，与OH一样重要，这是与传统方法衡量最具挑战性的最具挑战性。 Therefore, measurement of the total ozone reactivity has potential to provide new insight into the total budget of reactive BVOCs present in the atmosphere, and the extent to which it is currently substantially underestimated - a hypothesis attracting growing support from a range of recent measurements.Within this project, we will develop a prototype ozone reactivity instrument, building upon a feasibility study carried out in our laboratory;我们将通过单个VOC标准测试系统性能，并通过实验室外壳中的植物标本中复杂的VOC混合物来测试系统的性能，我们将证明其适用性，以评估响应环境压力的全树的BVOC发射变化。后一个目标将通过在新南威尔士州里士满的Hawkesbury Forest实验（HFE）地点的国际独特的全树室进行测量来实现，在那里我们将衡量桉树的总臭氧反应性的变化，这是RH，温度和二氧化碳的变化的功能（400 ppm [即400 ppm [即当前日] vs vs 640 ppm）。在该项目的期限内，只能进行有限的实验 - 但是，这些实验将为BVOC从植被对环境变化的总体排放的响应提供独特的见解，这是对项目的未来利用。该项目的实现将实现技术准备水平（TRL）4-基本验证在受控环境中。遵循此概念验证工作（即此提案之外），我们已经确定了该技术初始现场部署的机会，可以在当今的条件下从成熟的OAK林地进行首次测量，以对环境空气中的BVOC总BVOC臭氧反应性进行首次测量，并预计未来的CO2水平。