Hand J L, Prenni A J, Raffuse S M, Hyslop N P, Malm W C, Schichtel B A
Cooperative Institute for Research in the Atmosphere Colorado State University Fort Collins CO USA.
National Park Service Air Resources Division Lakewood CO USA.
J Geophys Res Atmos. 2024 Dec 16;129(23):e2024JD042579. doi: 10.1029/2024JD042579. Epub 2024 Dec 1.
The spatial and seasonal variability in the composition of major PM (particles with aerodynamic diameters less than 2.5 μm) aerosol species in the United States were characterized using data from ground-based aerosol monitoring networks. The IMPROVE (Interagency Monitoring of Protected Visual Environments) network and the Chemical Speciation Network (CSN) operate in mostly rural/remote or urban/suburban sites, respectively. The networks have similar sampling schedules and analysis methods. Regional, monthly, and annual mean concentrations from 2019 to 2022 were calculated for ammonium sulfate (AS), ammonium nitrate (AN), particulate organic matter (POM), elemental carbon (EC), fine dust (FD), and sea salt (SS), as well as their relative contributions to reconstructed PM mass (RCFM). Organic aerosols were the largest contributor to RCFM across the United States (>40% annually, up to 80% monthly), with significant impacts from biomass smoke on POM and EC concentrations, contributions, and seasonality. AS concentrations and contributions were similar in urban and rural regions and contributed <20% annually to RCFM, considerably less than two decades ago. In general, urban concentrations were greater for AN, POM, and EC, suggesting additional urban sources. Some species, such as POM, FD, and AN, exhibited strong seasonal variability due to episodic source impacts or seasonal formation conditions. Evaluating the urban and rural monthly variability of major aerosol species is necessary for understanding the impacts of emission sources, regional transport, and atmospheric processes governing aerosol concentrations in the atmosphere.
利用地面气溶胶监测网络的数据，对美国主要细颗粒物（空气动力学直径小于2.5微米的颗粒物）气溶胶种类组成的空间和季节变化特征进行了研究。IMPROVE（受保护视觉环境跨部门监测）网络和化学形态网络（CSN）分别在大部分农村/偏远地区或城市/郊区站点运行。这两个网络具有相似的采样计划和分析方法。计算了2019年至2022年硫酸铵（AS）、硝酸铵（AN）、颗粒有机物（POM）、元素碳（EC）、细粉尘（FD）和海盐（SS）的区域、月度和年度平均浓度，以及它们对重构细颗粒物质量（RCFM）的相对贡献。在美国，有机气溶胶对RCFM的贡献最大（每年>40%，每月高达80%），生物质烟雾对POM和EC的浓度、贡献和季节性有显著影响。AS的浓度和贡献在城市和农村地区相似，每年对RCFM的贡献<20%，远低于二十年前。一般来说，城市地区AN、POM和EC的浓度更高，表明存在额外的城市来源。一些物种，如POM、FD和AN，由于偶发性源影响或季节性形成条件，表现出强烈的季节变化。评估主要气溶胶物种的城市和农村月度变化对于理解排放源、区域传输和控制大气中气溶胶浓度的大气过程的影响至关重要。
