气候变化领域集成服务门户(CCPortal): Contrasting physical properties of black carbon in urban Beijing between winter and summer

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DOI	10.5194/acp-19-6749-2019
	Contrasting physical properties of black carbon in urban Beijing between winter and summer
	Liu D.; Joshi R.; Wang J.; Yu C.; Allan J.D.; Coe H.; Flynn M.J.; Xie C.; Lee J.; Squires F.; Kotthaus S.; Grimmond S.; Ge X.; Sun Y.; Fu P.
发表日期	2019
ISSN	16807316
起始页码	6749
结束页码	6769
卷号	19 期号:10
英文摘要	Black carbon (BC) is known to have major impacts on both human health and climate. The populated megacity represents the most complex anthropogenic BC emissions where the sources and related impacts are very uncertain. This study provides source attribution and characterization of BC in the Beijing urban environment during the joint UK-China APHH (Air Pollution and Human Health) project, in both winter (November-December 2016) and summer (May-June 2017). The size-resolved mixing state of BCcontaining particles was characterized by a single-particle soot photometer (SP2) and their mass spectra was measured by a soot particle aerosol mass spectrometer (SP-AMS). The refractory BC (rBC) mass loading was around a factor of 2 higher in winter relative to summer, and more variable coatings were present, likely as a result of additional surface emissions from the residential sector and favourable condensation in the cold season. The characteristics of the BC were relatively independent of air mass direction in summer, whereas in winter air masses from the Northern Plateau were considerably cleaner and contained less-coated and smaller BC, but the BC from the Southern Plateau had the largest core size and coatings. We compare two online source apportionment methods using simultaneous measurements made by the SP2, which measures physical properties of BC, and the chemical approach using the positive matrix factorization (PMF) of mass spectra from the SP-AMS for the first time. A method is proposed to isolate the BC from the transportation sector using a mode of small BC particles (core diameter Dc < 0:18 μm and coating thickness ct < 50 nm). This mode of BC highly correlated with NOx concentration in both seasons (∼ 14 ng m-3 BC ppb-1 NOx) and corresponded with the morning traffic rush hour, contributing about 30 % and 40 % of the total rBC mass (35 % and 55 % in number) in winter and summer respectively. The BC from coal burning or biomass burning was characterized by moderate coatings (ct D 50-200 nm) contributing ∼ 20 %-25 % of rBC mass. Large uncoated BC particles (Dc > 0:18 μm and ct < 50 nm) were more likely to be contributed by coal combustion, as these particles were not present in urban London. This mode was present in Beijing in both winter (∼ 30 %-40 % rBC mass) and summer (∼ 40 % rBC mass) but may be dominated by the residential and industrial sector respectively. The contribution of BC thickly coated with secondary species (ct > 200 nm) to the total rBC mass increased with pollution level in winter but was minor in summer. These large BC particles importantly enhanced the absorption efficiency at high pollution levels-in winter when PM1 > 100 μg m-3 or BC > 2 μg m-3, the absorption efficiency of BC increased by 25 %-70 %. The reduction of emissions of these large BC particles and the precursors of the associated secondary coating will be an effective way of mitigating the heating effect of BC in urban environments. © 2019 Author(s).
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/144392
作者单位	Department of Atmospheric Sciences, School of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Centre for Atmospheric Sciences, School of Earth and Environmental Sciences, University of Manchester, Manchester, United Kingdom; Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China; School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, China; National Centre for Atmospheric Science, University of Manchester, Manchester, United Kingdom; Department of Chemistry, National Centre for Atmospheric Science, University of York, York, United Kingdom; Department of Meteorology, University of Reading, United Kingdom
推荐引用方式 GB/T 7714	Liu D.,Joshi R.,Wang J.,et al. Contrasting physical properties of black carbon in urban Beijing between winter and summer[J],2019,19(10).
APA	Liu D..,Joshi R..,Wang J..,Yu C..,Allan J.D..,...&Fu P..(2019).Contrasting physical properties of black carbon in urban Beijing between winter and summer.Atmospheric Chemistry and Physics,19(10).
MLA	Liu D.,et al."Contrasting physical properties of black carbon in urban Beijing between winter and summer".Atmospheric Chemistry and Physics 19.10(2019).