Lu Siying, Bhattarai Chiranjivi, Samburova Vera, Khlystov Andrey
Division of Atmospheric Sciences, Desert Research Institute Reno Nevada USA
Department of Physics, University of Nevada Reno Nevada USA.
Environ Sci Atmos. 2025 Mar 13;5(4):502-516. doi: 10.1039/d5ea00007f. eCollection 2025 Apr 10.
Wildfires are a major source of aerosols during summer in the western United States. Aerosols emitted from wildfires could significantly affect air quality, human health, and the global climate. This study conducted a comparison of aerosol characteristics during wildfire smoke-influenced and non-smoke-influenced days. Ambient particle size distribution (PSD) data were collected in Reno, Nevada, between July 2017 and October 2020. During this period, the site was impacted by smoke from over a hundred wildfires burning in a wide range of ecosystems in the western United States located at different distances from the measurement site. The smoke-influenced days were identified using satellite images, a hazard mapping system, and wind back-trajectory. Positive matrix factorization (PMF) was applied to identify the main sources and their characteristics. The wildfire aerosols were observed to have a number mode diameter of 212 nm, which is significantly larger than aerosols on non-smoke-influenced days (61 nm). In addition to the increase in particle size, wildfires made a large contribution to PM and CO concentrations. During fire-prone months (July, August, and September) from 2016 to 2021, 56% to 65% of PM and 18% to 26% of CO concentrations could be attributed to wildfire emissions in the study area. On an annual basis, wildfire emissions were responsible for 35% to 47% of PM concentrations and 5% to 12% of CO concentrations.
野火是美国西部夏季气溶胶的主要来源。野火排放的气溶胶会显著影响空气质量、人类健康和全球气候。本研究对受野火烟雾影响和不受烟雾影响的日子里的气溶胶特征进行了比较。2017年7月至2020年10月期间，在内华达州里诺收集了环境颗粒物粒径分布（PSD）数据。在此期间，该地点受到来自美国西部广泛生态系统中一百多起野火产生的烟雾影响，这些野火位于距离测量地点不同距离处。利用卫星图像、灾害绘图系统和风向回溯轨迹确定受烟雾影响的日子。应用正定矩阵因子分解（PMF）来识别主要来源及其特征。观察到野火气溶胶的数模直径为212纳米，明显大于非烟雾影响日子里的气溶胶（61纳米）。除了粒径增大外，野火对颗粒物和一氧化碳浓度也有很大贡献。在2016年至2021年火灾频发的月份（7月、8月和9月），研究区域内56%至65%的颗粒物和18%至26%的一氧化碳浓度可归因于野火排放。从年度来看，野火排放占颗粒物浓度的35%至47%，占一氧化碳浓度的5%至12%。
