Measurement of Halogen Species by Resonance Fluorescence

通过共振荧光测量卤素物质

基本信息

批准号：
NE/G018839/1
负责人：
William Bloss
金额：
$ 31.46万
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：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG018839%2F1
关键词：
Measurement Halogen Species Resonance Fluorescence

项目摘要

Atmospheric ozone levels are of critical importance to human health and the environment for a number of reasons: In the stratosphere, the ozone layer absorbs harmful solar UV radiation. In the troposphere, ozone is a pollutant, harmful to human health, vegetation and materials, and is a greenhouse gas, but is also the major source of the key atmospheric oxidant OH, which initiates the removal of most compounds emitted to the atmosphere, including pollutants and greenhouse gases such as methane. Understanding the processes which may affect the atmospheric abundance of ozone and OH is therefore of considerable societal importance. Compounds containing the halogen atoms iodine and bromine, are known to be released to the atmosphere in marine environments through biological and physical processes. Once in the gas phase, the constituent halogen atoms may be released through photolysis, leading to a number of effects upon tropospheric composition: Catalytic ozone destruction, alteration of HOx and NOx ratios and abundance, and in the case of iodine compounds the formation of new particles which may grow and contribute to CCN concentrations, hence potentially affecting radiative balance and climate. It is therefore important to understand the sources and distribution of halogen species in the lower atmosphere, and to quantify their potential effects upon atmospheric composition. The main aim of this project is to develop a new instrument for the measurement of halogen (iodine and bromine) content in the lower atmosphere. The technique of resonance fluorescence will be used to detect halogen atoms; this then permits the detection of ambient I and Br atoms, photolabile iodine- and bromine-containing species (detected following broadband UV-visible photolysis leading to the release of their constituent halogen atoms), and BrO radicals (detected through chemical conversion to Br by reaction with added NO). A prototype instrument for the detection of iodine species, funded through a previous NERC award, was developed and a trial field deployment successfully completed in summer 2007, demonstrating the viability of the concept and the basic measurement capability. This project, a continuation of the previous award, will develop the prototype into a practical field system, improving the performance and extending the detection capability to bromine species. A second aim of the project is to apply the system to measure iodine compounds on a forthcoming research cruise in the Eastern Pacific Ocean, and to perform point measurements of bromine species at a coastal site in the North-East Atlantic. The former measurements will assess the boundary layer iodine activity in an area identified by satellite observations to be of high halogen activity, and will constrain the total gas-phase iodine content of the lower atmosphere, hence determining the concentration of condensable iodine species which are potentially available to form new particles. The latter experiment, which will include the first measurements of photolabile bromine content in the atmosphere, will determine the spatial distribution (coastal vs. open ocean) of bromine activity at Mace Head (previously only measured using long-path absorption instruments which average spatial heterogeneity), and also provide a field test / demonstration of the full, optimised instrument capability.

大气臭氧水平对于人类健康和环境至关重要，原因有很多：在平流层中，臭氧层吸收有害的太阳紫外线辐射。在对流层中，臭氧是一种污染物，对人类健康，植被和材料有害，是一种温室气体，但也是关键大气氧化剂OH的主要来源，它启动去除大多数化合物，包括污染物和甲烷等温室气体，例如甲烷。因此，了解可能影响臭氧大气丰度的过程，因此OH具有相当大的社会重要性。众所周知，含有卤素原子碘和溴的化合物通过生物学和物理过程在海洋环境中释放到大气中。一旦处于气相，可以通过光解释放组成的卤素原子，从而导致对对流层组成的许多影响：催化臭氧的破坏，HOX和NOX比和丰度的改变，以及在碘化的情况下，可能成长并有助于CCN浓度的新颗粒的形成，并有助于CCN的浓度，并且会影响范围，并且会影响范围。因此，重要的是要了解低大气中卤素物种的来源和分布，并量化它们对大气成分的潜在影响。该项目的主要目的是开发一种新的仪器，用于测量低大气中的卤素（碘和溴）含量。共振荧光技术将用于检测卤素原子。然后，这允许检测环境I和BR原子，光构碘和含溴的物种（在宽带UV可见光解后检测，导致其成分卤素原子释放）以及BRO自由基（通过添加的反应通过化学转化为BR检测到BR检测到BR）。开发了通过先前的NERC奖励资助的碘物种的原型工具，并于2007年夏季成功完成了试验现场部署，证明了该概念的可行性和基本的测量能力。该项目是上一个奖项的延续，将将原型开发为实用的现场系统，改善性能并将检测能力扩展到溴物种。该项目的第二个目的是应用该系统在东部太平洋即将进行的研究巡航上测量碘化合物，并在东北大西洋的沿海地区对溴物种进行点测量。前者测量值将评估通过卫星观测值确定为高卤素活性的区域的边界层碘活性，并将限制下部大气中的总气相碘含量，因此确定可能可用于形成新颗粒的可凝聚力碘物种的浓度。后一个实验将包括大气中光拟曲溴含量的首次测量，将确定梅斯头处的溴活性的空间分布（沿海与开阔的海洋）（以前仅使用平均空间异质性的长路径吸收仪器进行测量），还提供了完整，优化仪器功能的现场测试 /演示。