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Empirical Insights Into the Fate of Ammonia in Western U.S. Wildfire Smoke Plumes
Author(s) -
Lindaas Jakob,
Pollack Ilana B.,
Calahorrano Julieta Juncosa,
O'Dell Katelyn,
Garofalo Lauren A.,
Pothier Matson A.,
Farmer Delphine K.,
Kreidenweis Sonia M.,
Campos Teresa,
Flocke Frank,
Weinheimer Andrew J.,
Montzka Denise D.,
Tyndall Geoffrey S.,
Apel Eric C.,
Hills Alan J.,
Hornbrook Rebecca S.,
Palm Brett B.,
Peng Qiaoyun,
Thornton Joel A.,
Permar Wade,
Wielgasz Catherine,
Hu Lu,
Pierce Jeffrey R.,
Collett Jeffrey L.,
Sullivan Amy P.,
Fischer Emily V.
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd033730
Subject(s) - aerosol , particulates , ammonium , plume , environmental chemistry , smoke , nitrogen , chemistry , ammonia , deposition (geology) , sulfate , ammonium sulfate , nitrate , atmospheric sciences , meteorology , geology , geomorphology , organic chemistry , physics , chromatography , sediment
Wildfires are a major source of gas‐phase ammonia (NH 3 ) to the atmosphere. Quantifying the evolution and fate of this NH 3 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 NH 3 and its relationship with particulate ammonium ( p NH 4 ) within wildfire smoke plumes in the western U.S. during summer 2018. We show that the e‐folding loss timescale of NH 3 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 p NH 4 in each plume sampled, suggesting that formation of ammonium nitrate (NH 4 NO 3 ) is likely. We find wide variability in how close our in situ measurements of NH 4 NO 3 are to those expected in a dry thermodynamic equilibrium, and find that NH 4 NO 3 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 p NH 4 and the fraction of particulate nitrate ( p NO 3 ) in the aerosol with temperature, providing additional evidence of the presence of NH 4 NO 3 and the influence of injection height on gas‐particle partitioning of NH 3 .