Wintertime Formaldehyde: Airborne Observations and Source Apportionment Over the Eastern United States
Wintertime Formaldehyde: Airborne Observations and Source Apportionment Over the Eastern United States
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DOI：
10.1029/2020jd033518
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发表时间：
2021-01
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影响因子：
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通讯作者：
Jaime R. Green;M. Fiddler;D. Fibiger;E. McDuffie;J. Aquino;T. Campos;Viral Shah;L. Jaeglé;J. Thornton;J. Digangi;G. Wolfe;S. Bililign;S. Brown
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作者：
Jaime R. Green;M. Fiddler;D. Fibiger;E. McDuffie;J. Aquino;T. Campos;Viral Shah;L. Jaeglé;J. Thornton;J. Digangi;G. Wolfe;S. Bililign;S. Brown
甲醛（HCHO）是由城市的直接排放源和城市烟雾的光化学反应产生的二次产物。甲醛与对流层臭氧的形成有关，并有助于城市烟雾其他成分的光化学反应。在这项研究中，污染羽流拦截在冬季调查的运输，排放和反应性（冬季）运动被用来调查和表征的形成HCHO的几个人为示踪剂。分析飞机拦截结合详细的化学箱模拟顺风几个城市表明，最重要的贡献，观察到的甲醛是一次排放。对单一羽流的箱形模型分析表明，次级来源占观测到的HCHO的21 ± 10%。在美国东北部，从俄亥俄州到纽约，观测到的HCHO/CO比率在0.2%到0.6%之间，与直接排放和最多适度的光化学生产相一致。通过对城市影响区上空重复垂直廓线的夜间边界层和残留层的分析表明，HCHO的直接排放通量为1.3 × 1014分子cm − 2 h − 1。在佐治亚州亚特兰大的一项案例研究中，夜间HCHO与CO的比例为0.6%-1.8%，与O3呈反相关。观测结果与城市空气中直接排放的HCHO与受HCHO光化学生成更快影响的HCHO之间的混合一致。根据测量数据确定的HCHO/CO排放比是NEI 2017年排放数据库的2.3 - 15倍。观测到的最大HCHO/CO为1.7%-1.8%，位于热电厂附近。
Formaldehyde (HCHO) is generated from direct urban emission sources and secondary production from the photochemical reactions of urban smog. HCHO is linked to tropospheric ozone formation, and contributes to the photochemical reactions of other components of urban smog. In this study, pollution plume intercepts during the Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign were used to investigate and characterize the formation of HCHO in relation to several anthropogenic tracers. Analysis of aircraft intercepts combined with detailed chemical box modeling downwind of several cities suggests that the most important contribution to observed HCHO was primary emission. A box model analysis of a single plume suggested that secondary sources contribute to 21 ± 10% of the observed HCHO. Ratios of HCHO/CO observed in the northeast US, from Ohio to New York, ranging from 0.2% to 0.6%, are consistent with direct emissions combined with at most modest photochemical production. Analysis of the nocturnal boundary layer and residual layer from repeated vertical profiling over urban influenced areas indicate a direct HCHO emission flux of 1.3 × 1014 molecules cm−2 h−1. In a case study in Atlanta, GA, nighttime HCHO exhibited a ratio to CO (0.6%–1.8%) and was anti‐correlated with O3. Observations were consistent with mixing between direct HCHO emissions in urban air masses with those influenced by more rapid HCHO photochemical production. The HCHO/CO emissions ratios determined from the measured data are 2.3–15 times greater than the NEI 2017 emissions database. The largest observed HCHO/CO was 1.7%–1.8%, located near co‐generating power stations.