Quantifying the Contributions of Aerosol- and Snow-Produced ClNO2 through Observations and 1D Modeling
Quantifying the Contributions of Aerosol- and Snow-Produced ClNO2 through Observations and 1D Modeling
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DOI：
10.1021/acsearthspacechem.3c00237
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发表时间：
2023-12
影响因子：
3.4
通讯作者：
Daun Jeong;S. M. McNamara;Qianjie Chen;J. Mirrielees;J. Edebeli;Kathryn D. Kulju;Siyuan Wang;Laila Hayani;R. Kirpes;N. Lata;S. China;Jose D. Fuentes;K. Pratt
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文献类型：
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作者：
Daun Jeong;S. M. McNamara;Qianjie Chen;J. Mirrielees;J. Edebeli;Kathryn D. Kulju;Siyuan Wang;Laila Hayani;R. Kirpes;N. Lata;S. China;Jose D. Fuentes;K. Pratt
硝基氯(ClNO2)是一种在夜间大气边界层中形成和积累的自由基库，受燃烧排放和氯化物(如海盐和道路盐)的影响。日出时，ClNO2迅速光解，产生高活性的氯自由基(Cl.)，通过产生二次空气污染物影响空气质量。最近的研究表明，道路盐气溶胶和盐化积雪是冬季城市环境中ClNO2的来源；然而，每种氯源的数量贡献尚不清楚。在这项研究中，我们通过一个观测约束的雪-大气耦合一维模式应用于美国密歇根州卡拉马祖的冬季，研究了作为ClNO2来源的气溶胶粒子和盐分积雪的垂直分辨贡献。模式模拟表明，城市积雪排放的ClNO2可以垂直输送到整个大气边界层，是ClNO2的一个重要来源，在地面附近贡献了∼的60%。模拟的积雪ClNO2释放率比观测得到的释放率高6(±7)倍，这表明并不是所有的积雪氯化物都可用于反应。为了最好地模拟观测到的地表ClNO2，需要从气溶胶颗粒和雪排放中产生ClNO2。对颗粒物产生的ClNO2使用传统的总体参数化大大高估了ClNO2，这是因为假设整个颗粒物具有等量的五氧化二氮(N2O5)吸收和氯的有效性。相比之下，基于化学分解表面积的参数化略微低估了观测结果，并存在来自住宅木材燃烧颗粒产生的ClNO2的不确定性。
Nitryl chloride (ClNO2) is a radical reservoir that forms and accumulates in the nocturnal atmospheric boundary layer influenced by combustion emissions and chloride (e.g., sea salt and road salt). Upon sunrise, ClNO2rapidly photolyzes to generate highly reactive chlorine radicals (Cl•) that affect the air quality by generating secondary air pollutants. Recent studies have shown road salt aerosols and saline snowpack to be sources of ClNO2in the wintertime urban environment; however, the quantitative contributions of each chloride source are not known. In this study, we examine the vertically resolved contributions of aerosol particles and saline snowpack as sources of ClNO2by using an observationally constrained snow–atmosphere coupled one-dimensional model applied to wintertime Kalamazoo, Michigan, U.S. Model simulations show that ClNO2emitted from urban snowpack can be vertically transported throughout the entire atmospheric boundary layer and can be a significant source of ClNO2, contributing up to ∼60% of the ClNO2budget near the surface. Modeled snowpack ClNO2emission rates were 6 (±7) times higher than the observationally derived emission rates, suggesting that not all snow chloride is available for reaction. ClNO2production from both aerosol particles and snow emissions are required to best simulate the observed surface-level ClNO2. Using the traditional bulk parameterization for ClNO2produced from particles significantly overestimated ClNO2due to the assumption of having equivalent dinitrogen pentoxide (N2O5) uptake and chloride availability for the entire particle population. In comparison, the chemically resolved surface area-based parameterization slightly underestimated the observations and had uncertainties deriving from ClNO2production from residential wood burning particles.