Haskins J D, Lopez-Hilfiker F D, Lee B H, Shah V, Wolfe G M, DiGangi J, Fibiger D, McDuffie E E, Veres P, Schroder J C, Campuzano-Jost P, Day D A, Jimenez J L, Weinheimer A, Sparks T, Cohen R C, Campos T, Sullivan A, Guo H, Weber R, Dibb J, Greene J, Fiddler M, Bililign S, Jaeglé L, Brown S S, Thornton J A
Department of Atmospheric Sciences, University of Washington, Seattle, WA USA.
Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD USA.
Geophys Res Lett. 2019 Dec 28;46(24):14826-14835. doi: 10.1029/2019GL085498. Epub 2019 Dec 13.
During winter in the mid-latitudes, photochemical oxidation is significantly slower than in summer and the main radical oxidants driving formation of secondary pollutants, such as fine particulate matter and ozone, remain uncertain, owing to a lack of observations in this season. Using airborne observations, we quantify the contribution of various oxidants on a regional basis during winter, enabling improved chemical descriptions of wintertime air pollution transformations. We show that 25-60% of NO is converted to NO via multiphase reactions between gas-phase nitrogen oxide reservoirs and aerosol particles, with ~93% reacting in the marine boundary layer to form >2.5 ppbv ClNO. This results in >70% of the oxidizing capacity of polluted air during winter being controlled, not by typical photochemical reactions, but from these multiphase reactions and emissions of volatile organic compounds, such as HCHO, highlighting the control local anthropogenic emissions have on the oxidizing capacity of the polluted wintertime atmosphere.
在中纬度地区的冬季，光化学氧化作用明显比夏季慢，由于该季节缺乏观测数据，驱动细颗粒物和臭氧等二次污染物形成的主要自由基氧化剂仍不明确。利用机载观测数据，我们在区域尺度上量化了冬季各种氧化剂的贡献，从而改进了对冬季空气污染转化的化学描述。我们发现，气相氮氧化物储库与气溶胶颗粒之间的多相反应可将25%至60%的一氧化氮（NO）转化为二氧化氮（NO₂），其中约93%在海洋边界层发生反应，形成浓度大于2.5 ppbv的氯硝基（ClNO₂）。这导致冬季污染空气中超过70%的氧化能力并非由典型的光化学反应控制，而是由这些多相反应以及挥发性有机化合物（如甲醛，HCHO）的排放所控制，这突出了当地人为排放对污染的冬季大气氧化能力的控制作用。
