Urban oxidising capacity measurements using inert and reactive tracers

使用惰性和反应性示踪剂测量城市氧化能力

基本信息

批准号：
NE/K01501X/1
负责人：
Dudley Shallcross
金额：
$ 56.66万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FK01501X%2F1
关键词：
Urban oxidising capacity measurements using

项目摘要

By definition, the urban environment is one where many people either live or work. During the course of a day, people will be outdoors for varying lengths of time and be exposed to different levels of air pollutants. During daytime, sunlight can provide the energy needed to produce the hydroxyl radical (written as HO), which is an extremely reactive species that acts like a detergent in the atmosphere, reacting with air pollutants. Therefore, we want to know how much HO there is in the urban atmosphere and how its level changes over the course of a day and from day to day as a function of time of the year. It is possible to measure HO directly using an instrument called FAGE and this has been carried out for some cities in the UK (e.g. Birmingham and London). These data have helped us to understand how HO varies in one location but the instrument FAGE is too expensive to replicate to allow us to make measurements across a city. HO is made and destroyed very rapidly, so a measurement of HO also tells us the ratio of the rate of its production to the rate of its removal and indeed FAGE can also tell us about the rate of its removal. Therefore, we can calculate the rate of production from these measurements, but these other measurements from a number of cities suggest that the rate of production of HO is underestimated based on our current understanding. One possibility is that there are missing sources that we don't know about? Given the importance of HO and other oxidants to urban air quality it is vital to try to work out what these missing sources are.With this in mind we have developed a new technique to allow us to measure the amount of HO (and other detergents) pollutants encounter as they move through the urban environment. In this way we will be able to build up a picture of how removal rates for pollutants varies across a City as a function of time of day, season, pollution loading etc. We will also be able to estimate how rapidly particles are made in the urban environment and begin to understand what controls their production. Particles can be released into the atmosphere directly, e.g. from car exhausts, (called primary particles) but can also be made in the atmosphere, a so called secondary particles. We want to know more about the sources of secondary particles as we can make reasonable estimates of primary particle sources. Particles are known to be bad for air quality and a reduction in levels would be of great benefit. In order to make these measurements we will release small amounts of organic molecules that react with oxidants such as HO and some molecules that don't react with anything. We have tagged the reactive molecules so we can tell them apart from ones that are there already into the city and will measure the levels of both reactive and inert species downwind of the release point. As these molecules disperse their level will drop because of dilution and the inert species will tell us the dilution rate, the reactive ones will drop even more as they will not only disperse but also react. By using these two pieces of information we can estimate their chemical removal rates and hence the amount of HO present. Other measurements of pollutants and meteorology will be made at the same time and we will then be able to estimate how quickly these pollutants are removed. Computer models that contain our current knowledge of urban air quality will be compared with all the measurement data and we will then be able to test a number of hypotheses for the missing source of HO and other oxidants. We will also carry out studies at night where HO levels are very low and a different oxidant called the nitrate radical (NO3) takes over. We have an instrument that can make measurements of NO3 and so we can compare the measurement of NO3 in one location with the NO3 experienced by pollutants as they pass through the city. In this way a detailed comparison can be made.

根据定义，城市环境是许多人生活或工作的环境。在一天中，人们在户外的时间会有所不同，并会接触到不同程度的空气污染物。白天，阳光可以提供产生羟基自由基（写作 H2O）所需的能量，羟基自由基是一种极其活泼的物质，在大气中就像清洁剂一样，与空气污染物发生反应。因此，我们想知道城市大气中含有多少 H2O，以及其水平在一天中以及每天随一年中不同时间的变化如何变化。可以使用名为 FAGE 的仪器直接测量 H2O，这已在英国的一些城市（例如伯明翰和伦敦）进行。这些数据帮助我们了解 HO 在一个地点的变化情况，但 FAGE 仪器太昂贵，无法复制，无法让我们在整个城市进行测量。 H2O 的产生和破坏非常迅速，因此 H2O 的测量还可以告诉我们其生成速率与其去除速率的比率，实际上 FAGE 也可以告诉我们其去除速率。因此，我们可以根据这些测量结果计算出 H2O 的生产率，但来自许多城市的其他测量结果表明，根据我们目前的了解，H2O 的生产率被低估了。一种可能性是缺少我们不知道的来源？鉴于 H2O 和其他氧化剂对城市空气质量的重要性，尝试找出这些缺失的来源至关重要。考虑到这一点，我们开发了一种新技术来测量 H2O（和其他清洁剂）的含量污染物在城市环境中移动时会遇到。通过这种方式，我们将能够描绘出一个城市污染物去除率如何随着一天中的时间、季节、污染负荷等而变化的情况。我们还将能够估计城市中颗粒产生的速度。城市环境并开始了解是什么控制着他们的生产。颗粒可以直接释放到大气中，例如来自汽车尾气（称为初级颗粒），但也可以在大气中产生，即所谓的次级颗粒。我们想更多地了解二次粒子的来源，因为我们可以对一次粒子的来源做出合理的估计。众所周知，颗粒物对空气质量有害，降低颗粒物含量将带来巨大好处。为了进行这些测量，我们将释放少量与氧化剂（例如 H2O）发生反应的有机分子以及一些不与任何物质发生反应的分子。我们已经对活性分子进行了标记，这样我们就可以将它们与已经进入城市的分子区分开来，并测量释放点顺风处的活性物质和惰性物质的水平。当这些分子分散时，它们的水平会因稀释而下降，惰性物质会告诉我们稀释率，而活性物质会下降更多，因为它们不仅会分散而且会发生反应。通过使用这两条信息，我们可以估计它们的化学去除率，从而估计 H2O 的存在量。其他污染物和气象测量将同时进行，然后我们将能够估计这些污染物被清除的速度。包含我们当前城市空气质量知识的计算机模型将与所有测量数据进行比较，然后我们将能够测试一些关于 H2O 和其他氧化剂缺失来源的假设。我们还将在夜间进行研究，此时 H2O 水平非常低，并且由一种称为硝酸根 (NO3) 的不同氧化剂接管。我们有一种可以测量 NO3 的仪器，因此我们可以将一个地点的 NO3 测量值与污染物通过城市时所经历的 NO3 测量值进行比较。这样就可以进行详细的比较。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The first UK measurements of nitryl chloride using a chemical ionization mass spectrometer in central London in the summer of 2012, and an investigation of the role of Cl atom oxidation

DOI：
10.1002/2014jd022629
发表时间：
2015-06
期刊：
Journal of Geophysical Research: Atmospheres
影响因子：
0
作者：
T. Bannan;A. M. Booth;A. Bacak;J. Muller;K. Leather;Michael Le Breton;B. Jones;D. Young;H. Coe;J. Allan;S. Visser;J. Slowik;M. Furger;A. Prevot;James D. Lee;R. Dunmore;J. Hopkins;J. Hamilton;A. Lewis;L. Whalley;T. Sharp;D. Stone;D. Heard;Z. Fleming;R. Leigh;D. Shallcross;C. Percival
通讯作者：
T. Bannan;A. M. Booth;A. Bacak;J. Muller;K. Leather;Michael Le Breton;B. Jones;D. Young;H. Coe;J. Allan;S. Visser;J. Slowik;M. Furger;A. Prevot;James D. Lee;R. Dunmore;J. Hopkins;J. Hamilton;A. Lewis;L. Whalley;T. Sharp;D. Stone;D. Heard;Z. Fleming;R. Leigh;D. Shallcross;C. Percival

A study of global atmospheric budget and distribution of acetone using global atmospheric model STOCHEM-CRI

使用全球大气模型 STOCHEM-CRI 研究全球大气收支和丙酮分布