气候变化领域集成服务门户(CCPortal): Characterizing the ratio of nitrate to sulfate in ambient fine particles of urban Beijing during 2018

CCPortal

DOI	10.1016/j.atmosenv.2020.117662
	Characterizing the ratio of nitrate to sulfate in ambient fine particles of urban Beijing during 2018–2019
	Li S.; Zhang F.; Jin X.; Sun Y.; Wu H.; Xie C.; Chen L.; Liu J.; Wu T.; Jiang S.; Cribb M.; Li Z.
发表日期	2020
ISSN	1352-2310
卷号	237
英文摘要	A variety of legislative actions for air quality improvement have been conducted in China since 2013, and the emission control measures have achieved remarkable reduction in severe haze frequency. The composition of the fine particles may change along with the improved air quality, and thus may induce distinct environmental and climate effects in future. In this study, a very recent long-term dataset (2018–2019) of non-refractory chemical composition measured by a quadrupole aerosol chemical speciation monitor (Q-ACSM) observed in urban Beijing is applied to investigate the changes in ratio of nitrate (NO3−) to sulfate (SO42−) in PM2.5 (particulate matter with diameters of less than 2.5 μm). We show that the ratio of NO3− to SO42− varies seasonally, with a maximum in winter (1.6 ± 1.2) and a minimum in summer (0.7 ± 1.0). Compared with results from earlier studies showing a continuous increase in the ratio of NO3− to SO42− since 1999, a decline in the ratio is found during the period of 2018–2019. This is partially associated with an attenuated nitrate formation likely due to reduced nitrogen oxides emissions since 2016 in China. Our results suggest that the strict reduction control measures in place serve only to improve SO42− pollution in winter but not in summer when high SO42− levels are still observed. SO42− and NO3− concentrations during study periods together comprise 37–53% of PM2.5, presenting significant role in dominating the levels of PM2.5. In addition, we show that the ratio of NO3−/SO42− in warm seasons generally increases with increasing relative humidity (RH) due to enhanced NO3− hydrolysis formation, but with a maximum value of only ~1.0 that is pulled down by the high levels of sulfate in summer, while the dependence of the ratios on RH is more pronounced in cold seasons when multiple factors (regional transportation, planetary boundary layer, PBL and sources of sulfate, etc.) can impact nitrate levels. We finally characterize two typical processes that lead to the rapid accumulation of nitrate in the atmosphere over urban Beijing: the regional transportation and PBL variations, which is found driving heavy haze in cold seasons, and the hydrolysis formation and partitioning of NO3− that tends to impact the diurnal patterns of nitrate in warm seasons. © 2020 Elsevier Ltd
关键词	Fine particles Nitrate Seasonal variation Sulfate Trends
语种	英语
scopus关键词	Air quality; Boundary layers; Chemical speciation; Climate change; Emission control; Hydrolysis; Nitrates; Nitrogen oxides; Quality control; Sulfur compounds; Air quality improvement; Chemical compositions; Emission control measures; Legislative action; Multiple factors; Particulate Matter; Planetary boundary layers; Regional transportation; Urban transportation; ammonia; ammonium sulfate; black carbon; carbon monoxide; chloride; nitrate; nitrogen oxide; sulfate; accumulation; aerosol; air quality; chemical composition; emission control; haze; humidity; hydrolysis; nitrate; nitrous oxide; periurban area; pollutant transport; speciation (chemistry); aerosol; air pollution control; Article; boundary layer; chemical composition; China; circadian rhythm; exhaust gas; humidity; hydrolysis; oxidation; particulate matter; photooxidation; priority journal; seasonal variation; spring; summer; temperature; urban area; wind speed; winter; Beijing [China]; China
来源期刊	ATMOSPHERIC ENVIRONMENT
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/249071
作者单位	College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China; State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Earth System Science Interdisciplinary Center and Department of Atmospheric and Oceanic Science, University of Maryland, College ParkMD, United States
推荐引用方式 GB/T 7714	Li S.,Zhang F.,Jin X.,等. Characterizing the ratio of nitrate to sulfate in ambient fine particles of urban Beijing during 2018–2019[J],2020,237.
APA	Li S..,Zhang F..,Jin X..,Sun Y..,Wu H..,...&Li Z..(2020).Characterizing the ratio of nitrate to sulfate in ambient fine particles of urban Beijing during 2018–2019.ATMOSPHERIC ENVIRONMENT,237.
MLA	Li S.,et al."Characterizing the ratio of nitrate to sulfate in ambient fine particles of urban Beijing during 2018–2019".ATMOSPHERIC ENVIRONMENT 237(2020).