Airborne observations of formic acid using a chemical ionization mass spectrometer
Airborne observations of formic acid using a chemical ionization mass spectrometer
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DOI：
10.5194/amt-5-3029-2012
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发表时间：
2012-01-01
影响因子：
3.8
通讯作者：
Percival, C. J.
中科院分区：
文献类型：
--
作者：
Le Breton, M.;McGillen, M. R.;Percival, C. J.
2010年3月16日，FAAM BAe-146研究飞机上使用化学电离质谱仪使用I-试剂离子测量了英国上空甲酸混合比的首次空中测量。I-电离方案能够测量边界层中1 Hz处的甲酸混合比。使用来自甲酸源的飞行中标准加入校准来确定仪器灵敏度为35 +/- 6离子计数pptv（-1）s（-1）和检测限为25 pptv。常规测量是通过一个擦洗的入口，以确定仪器背景。在英国上空观测到三股甲酸羽流，分别来自伦敦、亨伯赛德和泰恩赛德。在整个飞行过程中，伦敦烟羽中的甲酸混合比最高，达到358 pptv。结果表明，两种烟羽中的甲酸与NOx和臭氧的相关性不显著，而CO和HCOOH的相关性较好，且两者的数据一致;采用轨迹模型对烟羽的来源进行了分析，并将模拟的混合比与实测值进行了比较。该模型低估了甲酸浓度高达2倍。这是由于模型中缺少源造成的，这些源被认为是主要人为来源的甲酸的初次排放和缺少生物源的前体排放，如异戊二烯，其原地氧化将导致甲酸的形成。
The first airborne measurements of formic acid mixing ratios over the United Kingdom were measured on the FAAM BAe-146 research aircraft on 16 March 2010 with a chemical ionization mass spectrometer using I- reagent ions. The I- ionization scheme was able to measure formic acid mixing ratios at 1 Hz in the boundary layer.In-flight standard addition calibrations from a formic acid source were used to determine the instrument sensitivity of 35 +/- 6 ion counts pptv(-1) s(-1) and a limit of detection of 25 pptv. Routine measurements were made through a scrubbed inlet to determine the instrumental background. Three plumes of formic acid were observed over the UK, originating from London, Humberside and Tyneside. The London plume had the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv. No significant correlations of formic acid with NOx and ozone were found, but a positive correlation was observed between CO and HCOOH within the two plumes where coincident data were recorded.A trajectory model was employed to determine the sources of the plumes and compare modelled mixing ratios with measured values. The model underestimated formic acid concentrations by up to a factor of 2. This is explained by missing sources in the model, which were considered to be both primary emissions of formic acid of mainly anthropogenic origin and a lack of precursor emissions, such as isoprene, from biogenic sources, whose oxidation in situ would lead to formic acid formation.