气候变化领域集成服务门户(CCPortal): Measurement report: Characterization of severe spring haze episodes and influences of long-range transport in the seoul metropolitan area in March 2019

CCPortal

DOI	10.5194/acp-20-11527-2020
	Measurement report: Characterization of severe spring haze episodes and influences of long-range transport in the seoul metropolitan area in March 2019
	Kim H.; Zhang Q.; Sun Y.
发表日期	2020
ISSN	1680-7316
起始页码	11527
结束页码	11550
卷号	20 期号:19
英文摘要	Severe haze episodes have occurred frequently in the Seoul metropolitan area (SMA) and throughout East Asian countries, especially during winter and early spring. Although notable progress has been attained in understanding these issues, the causes of severe haze formation have not yet been fully investigated. SMA haze is especially difficult to understand, because the area is impacted by both local emissions from anthropogenic and biogenic activities and emissions transported from upwind sources. Here, we investigated the emission sources and formation processes of particulate matter (PM) during three haze episodes measured in early spring of 2019, from 22 February to 2 April, using a high-resolution aerosol mass spectrometer (HR-AMS). Overall, the average concentration of nonrefractory submicron aerosol (NR-PM1) + BC (black carbon) was 35.1 μgm-3, which was composed of 38% organics, 12% SO4, 30% NO3, 13% NH4, and 5% BC. The organics had an average oxygen-to-carbon ratio (O/C) of 0.52 and an average organic mass to organic carbon ratio (OM/OC) of 1.86. Seven distinct sources of organic aerosols (OAs) were identified via positive matrix factorization (PMF) analysis of the HR-AMS data: vehicle-emitted hydrocarbon-like OA (HOA), cooking OA (COA), solid-fuel-burning emitted OA (SFOA), and four different types of oxidized secondary OA with varying oxidation degrees and temporal trends. Of the 40 d of the measurement period, 23 were identified as haze days (daily average: > 35 μgm-3), during which three severe haze episodes were recorded. In particular, PM1 concentration exceeded 100 μgm-3 during the first episode when an alert was issued, and strict emission controls were implemented in the SMA. Our results showed that nitrate dominated during the three haze episodes and accounted for 39 %-43% of the PM1 concentration on average (vs. 21 %- 24% during the low-loading period), for which there were indications of regional-transport influences. Two regionaltransport- influenced oxidized organic aerosols (OOAs), i.e., less oxidized OOA2 (LO-OOA2) and more oxidized OOA2 (MO-OOA2), contributed substantially to the total PM1 during the haze period (12 %-14% vs. 7% during the lowloading period), as well. In contrast, HOA and COA only contributed little (4 %-8% vs. 4 %-6% during the lowloading period) to the PM1 concentration during the haze days, indicating that local emissions were likely not the main reason for the severe haze issues. Hence, from simultaneous downwind (SMA) and upwind (Beijing) measurements using HR-AMS and ACSM (aerosol chemical speciation monitor) over the same period, the temporal variations in PM1 and each chemical species showed peak values on the order of Beijing (upwind) to the SMA for approximately 2 d. Furthermore, lead (Pb) derived from HR-AMS measurements was observed to increase significantly during the haze period and showed good correlations with MO-OOA2 and LO-OOA2, which is consistent with regional sources. A multiple linear regression model indicated that the transported regionally processed air masses contributed significantly to Pb in the SMA (31 %), especially during the haze period, although local burning was also important by contributing 38 %. The above results suggest that regional transport of polluted air masses might have played an important role in the formation of the haze episodes in the SMA during early spring. © Author(s) 2020.
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/141079
作者单位	Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul, 02792, South Korea; Department of Energy and Environmental Engineering, University of Science and Technology, Daejeon, 34113, South Korea; Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616, United States; State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
推荐引用方式 GB/T 7714	Kim H.,Zhang Q.,Sun Y.. Measurement report: Characterization of severe spring haze episodes and influences of long-range transport in the seoul metropolitan area in March 2019[J],2020,20(19).
APA	Kim H.,Zhang Q.,&Sun Y..(2020).Measurement report: Characterization of severe spring haze episodes and influences of long-range transport in the seoul metropolitan area in March 2019.Atmospheric Chemistry and Physics,20(19).
MLA	Kim H.,et al."Measurement report: Characterization of severe spring haze episodes and influences of long-range transport in the seoul metropolitan area in March 2019".Atmospheric Chemistry and Physics 20.19(2020).