Empirical Insights Into the Fate of Ammonia in Western U.S. Wildfire Smoke Plumes
Empirical Insights Into the Fate of Ammonia in Western U.S. Wildfire Smoke Plumes
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DOI：
10.1029/2020jd033730
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发表时间：
2021-06
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通讯作者：
J. Lindaas;Ilana B. Pollack;Julieta Juncosa Calahorrano;K. O’Dell;L. Garofalo;M. Pothier;D. Farmer;S. Kreidenweis;T. Campos;F. Flocke;A. Weinheimer;D. Montzka;G. Tyndall;E. Apel;A. Hills;R. Hornbrook;B. Palm;Q. Peng;J. Thornton;W. Permar;C. Wielgasz;Lu Hu;J. Pierce;J. Collett;A. Sullivan;E. Fischer
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作者：
J. Lindaas;Ilana B. Pollack;Julieta Juncosa Calahorrano;K. O’Dell;L. Garofalo;M. Pothier;D. Farmer;S. Kreidenweis;T. Campos;F. Flocke;A. Weinheimer;D. Montzka;G. Tyndall;E. Apel;A. Hills;R. Hornbrook;B. Palm;Q. Peng;J. Thornton;W. Permar;C. Wielgasz;Lu Hu;J. Pierce;J. Collett;A. Sullivan;E. Fischer
野火是大气中气态氨（NH3）的主要来源。量化NH3的演变和命运对于了解烟雾中二次气溶胶的形成及其对辐射平衡和氮沉降的影响非常重要。在这里，我们使用来自云化学，气溶胶吸收和氮的西部野火实验（WE-CAN）的数据，对NH3的e-折叠损失时间尺度及其与野火烟羽中颗粒铵（pNH 4）的关系添加新的经验约束2018年夏季美国西部。我们表明，相对于颗粒相分配，NH3的e折叠损失时间尺度范围为24 - 4000 min（中位数为55 min）。在这些相同的羽流中，氮氧化物的氧化被观察到的同时，在每个羽流采样的pNH 4的分数增加，这表明硝酸铵（NH 4 NO3）的形成是可能的。我们发现广泛的变化如何接近我们的原位测量NH 4 NO3的预期在干燥的热力学平衡，并发现NH 4 NO3是最有可能形成新鲜的，密集的烟雾羽流注入在较高的海拔和较低的温度。在化学上较老的烟雾中，我们观察到气溶胶中pNH 4的分数和颗粒硝酸盐（pNO 3）的分数与温度之间的相关性，为NH 4 NO3的存在以及喷射高度对NH3的气粒分配的影响提供了额外的证据。
Wildfires are a major source of gas‐phase ammonia (NH3) to the atmosphere. Quantifying the evolution and fate of this NH3 is important to understanding the formation of secondary aerosol in smoke and its accompanying effects on radiative balance and nitrogen deposition. Here, we use data from the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) to add new empirical constraints on the e‐folding loss timescale of NH3 and its relationship with particulate ammonium (pNH4) within wildfire smoke plumes in the western U.S. during summer 2018. We show that the e‐folding loss timescale of NH3 with respect to particle‐phase partitioning ranges from ∼24 to ∼4000 min (median of 55 min). Within these same plumes, oxidation of nitrogen oxides is observed concurrent with increases in the fraction of pNH4 in each plume sampled, suggesting that formation of ammonium nitrate (NH4NO3) is likely. We find wide variability in how close our in situ measurements of NH4NO3 are to those expected in a dry thermodynamic equilibrium, and find that NH4NO3 is most likely to form in fresh, dense smoke plumes injected at higher altitudes and colder temperatures. In chemically older smoke we observe correlations between both the fraction of pNH4 and the fraction of particulate nitrate (pNO3) in the aerosol with temperature, providing additional evidence of the presence of NH4NO3 and the influence of injection height on gas‐particle partitioning of NH3.