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DOI	10.5194/acp-20-15635-2020
	Measurements to determine the mixing state of black carbon emitted from the 2017-2018 California wildfires and urban Los Angeles
	Ko J.; Krasowsky T.; Ban-Weiss G.
发表日期	2020
ISSN	1680-7316
起始页码	15635
结束页码	15664
卷号	20 期号:24
英文摘要	The effects of atmospheric black carbon (BC) on climate and public health have been well established, but large uncertainties remain regarding the extent of the impacts of BC at different temporal and spatial scales. These uncertainties are largely due to the heterogeneous nature of BC in terms of its spatiotemporal distribution, mixing state, and coating composition. Here, we seek to further understand the size and mixing state of BC emitted from various sources and aged over different timescales using field measurements in the Los Angeles region. We measured refractory black carbon (rBC) with a single-particle soot photometer (SP2) on Catalina Island, California (∼ 70 km southwest of downtown Los Angeles) during three different time periods. During the first campaign (September 2017), westerly winds were dominant and measured air masses were representative of wellaged background over the Pacific Ocean. In the second and third campaigns (December 2017 and November 2018, respectively), atypical Santa Ana wind conditions allowed us to measure biomass burning rBC (BCbb) from air masses dominated by large biomass burning events in California and fossil fuel rBC (BCff) from the Los Angeles Basin. We observed that the emissions source type heavily influenced both the size distribution of the rBC cores and the rBC mixing state. BCbb had thicker coatings and larger core diameters than BBff. We observed a mean coating thickness (CTBC) of ∼ 40 70 nm and a count mean diameter (CMD) of ∼ 120 nm for BCbb. For BCff, we observed a CTBC of ∼ 5 15 nm and a CMD of ∼ 100 nm. Our observations also provided evidence that aging led to an increased CTBC for both BCbb and BCff. Aging timescales < ∼ 1 d were insufficient to thickly coat freshly emitted BCff. However, CTBC for aged BCff within aged background plumes was ∼ 35 nm thicker than CTBC for fresh BCff. Likewise, we found that CTBC for aged BCbb was ∼ 18 nm thicker than CTBC for fresh BCbb. The results presented in this study highlight the wide variability in the BC mixing state and provide additional evidence that the emissions source type and aging influence rBC microphysical properties. © 2020 Author(s).
英文关键词	air mass; biomass burning; black carbon; carbon emission; fossil fuel; mixing; urban area; wildfire; California; Los Angeles Basin; Pacific Ocean; Santa Ana [California]; United States; Anisotremus taeniatus
语种	英语
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/168881
作者单位	Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, United States; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States
推荐引用方式 GB/T 7714	Ko J.,Krasowsky T.,Ban-Weiss G.. Measurements to determine the mixing state of black carbon emitted from the 2017-2018 California wildfires and urban Los Angeles[J],2020,20(24).
APA	Ko J.,Krasowsky T.,&Ban-Weiss G..(2020).Measurements to determine the mixing state of black carbon emitted from the 2017-2018 California wildfires and urban Los Angeles.Atmospheric Chemistry and Physics,20(24).
MLA	Ko J.,et al."Measurements to determine the mixing state of black carbon emitted from the 2017-2018 California wildfires and urban Los Angeles".Atmospheric Chemistry and Physics 20.24(2020).