Seasonality of Formic Acid (HCOOH) in London during the ClearfLo Campaign
Seasonality of Formic Acid (HCOOH) in London during the ClearfLo Campaign
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DOI：
10.1002/2017jd027064
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发表时间：
2017-11-27
影响因子：
4.4
通讯作者：
Percival, Carl J.
中科院分区：
文献类型：
--
作者：
Bannan, Thomas J.;Booth, A. Murray;Percival, Carl J.
在2012年冬季测量之后，在2012年伦敦的夏季清洁空气伦敦（ClearfLo）活动期间使用化学电离质谱仪（CIMS）测量甲酸（HCOOH）和硝酸（HNO 3）。因此，可以更好地理解甲酸来源的季节依赖性。测得的平均甲酸浓度为1.3ppb，最大值为12.7ppb，显著高于冬季活动期间测得的浓度（分别为0.63ppb和6.7ppb）。在夏季活动期间，每天对甲酸进行校准，得到的灵敏度为1.2离子计数（-1）万亿分之一（ppt）（按体积计），检测限为34 ppt。在夏季活动期间，甲酸和人为排放（如NOx和CO）或与冬季高峰时段相关的峰值之间没有相关性。相反，观察到与太阳辐照度相关的甲酸峰。使用光化学轨迹模型进行分析，以确定这种甲酸的来源。通过烯烃的臭氧分解形成甲酸的贡献是重要的，但从生物来源的挥发性有机化合物的二次生产可能是最主要的甲酸来源在这个测量站点在夏季。
Following measurements in the winter of 2012, formic acid (HCOOH) and nitric acid (HNO3) were measured using a chemical ionization mass spectrometer (CIMS) during the Summer Clean Air for London (ClearfLo) campaign in London, 2012. Consequently, the seasonal dependence of formic acid sources could be better understood. A mean formic acid concentration of 1.3ppb and a maximum of 12.7ppb was measured which is significantly greater than that measured during the winter campaign (0.63ppb and 6.7ppb, respectively). Daily calibrations of formic acid during the summer campaign gave sensitivities of 1.2ion countss(-1)parts per trillion (ppt) by volume(-1) and a limit of detection of 34ppt. During the summer campaign, there was no correlation between formic acid and anthropogenic emissions such as NOx and CO or peaks associated with the rush hour as was identified in the winter. Rather, peaks in formic acid were observed that correlated with solar irradiance. Analysis using a photochemical trajectory model has been conducted to determine the source of this formic acid. The contribution of formic acid formation through ozonolysis of alkenes is important but the secondary production from biogenic VOCs could be the most dominant source of formic acid at this measurement site during the summer.