Chemical characteristics of PM2.5 and organic aerosol source analysis during cold front episodes in Hong Kong, China

2012 ◽  
Vol 118 ◽  
pp. 41-51 ◽  
Author(s):  
Yun-Chun Li ◽  
Jian Zhen Yu ◽  
Steven Sai Hang Ho ◽  
Zibing Yuan ◽  
Alexis K.H. Lau ◽  
...  
2015 ◽  
Vol 15 (1) ◽  
pp. 37-53 ◽  
Author(s):  
Y. J. Li ◽  
B. P. Lee ◽  
L. Su ◽  
J. C. H. Fung ◽  
C.K. Chan

Abstract. Atmospheric particulate matter (PM) remains poorly understood due to the lack of comprehensive measurements at high time resolution for tracking its dynamic features and the lack of long-term observation for tracking its seasonal variability. Here, we present highly time-resolved and seasonal compositions and characteristics of non-refractory components in PM with a diameter less than 1 μm (NR-PM1) at a suburban site in Hong Kong. The measurements were made with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) at the Hong Kong University of Science and Technology (HKUST) Air Quality Research Supersite for 4 months, with one in each season of the year. The average NR-PM1 concentration of ~ 15 μg m−3 is higher than those AMS measurements made in South Korea and Japan, but lower than those in North China, the Yangtze River Delta and the nearby Pearl River Delta. The seasonal dependence of the total NR-PM1 monthly averaged concentrations was small, but that of the fractions of the species in NR-PM1 was significant. Site characteristic plays an important role in the relative fractions of species in NR-PM1 and our results are generally consistent with measurements at other non-urban sites in this regard. Detailed analyses were conducted on the AMS data in the aspects of (1) species concentrations, (2) size distributions, (3) degree of oxygenation of organics, and (4) positive matrix factorization (PMF)-resolved organic factors in a seasonal context, as well as with air mass origin from back-trajectory analysis. Sulfate had the highest fraction in NR-PM1 (> 40%), and the surrogates of secondary organic species – semi-volatile oxygenated organic aerosol (SVOOA) and low-volatility oxygenated organic aerosol (LVOOA) – prevailed (~ 80%) in the organic portion of NR-PM1. Local contributions to the organic portion of NR-PM1 at this suburban site was strongly dependent on season. The hydrocarbon-like organic aerosol (HOA) factor related to local traffic emissions contributed > 10% to organic aerosols in spring and summer but only 6–7% in autumn and winter. The cooking organic aerosol (COA) factor contributed > 10% to organic aerosols in winter. With the aid of highly time-resolved data, diurnal patterns of the degree of oxygenation of organic aerosols were used to determine the sources and formation processes of the least understood organic portion of PM. The oxygen-to-carbon atomic ratio (O : C) and average carbon oxidation state OS C) showed little variation in autumn and winter, when the long-range transport of oxidized organics dominated, whereas they peaked in the afternoon in spring and summer, when locally produced secondary organic aerosol prevailed. Air mass origin, in contrast, had a strong influence on both NR-PM1 concentrations and the fractions of species in NR-PM1. The findings of the current study provide a better understanding of the role of air mass origin in the seasonal characteristics of the PM composition and the relative importance of local vs. transported organic aerosols in this region.


2017 ◽  
Author(s):  
Carlo Bozzetti ◽  
Imad El Haddad ◽  
Dalia Salameh ◽  
Kaspar Rudolf Daellenbach ◽  
Paola Fermo ◽  
...  

Abstract. We investigated the seasonal trends of OA sources affecting the air quality of Marseille (France) which is the largest harbor of the Mediterranean Sea. This was achieved by measurements of nebulized filter extracts using an aerosol mass spectrometer (offline-AMS). PM2.5 (particulate matter with an aerodynamic diameter


2009 ◽  
Vol 43 (6) ◽  
pp. 1196-1203 ◽  
Author(s):  
Xiao-Feng Huang ◽  
Jian Zhen Yu ◽  
Zibing Yuan ◽  
Alexis K.H. Lau ◽  
Peter K.K. Louie

2021 ◽  
Vol 21 (13) ◽  
pp. 10589-10608
Author(s):  
Yubo Cheng ◽  
Yiqiu Ma ◽  
Di Hu

Abstract. Here we conducted comprehensive chemical characterization and source apportionment of 49 PM2.5 samples collected in Hong Kong. Besides the major aerosol constituents, 39 polar organic species, including 14 secondary organic aerosol (SOA) tracers of isoprene, monoterpenes, β-caryophyllene, and naphthalene, were quantified using gas chromatography–mass spectrometry (GC–MS). Six factors, i.e., SOA, secondary sulfate (SS), biomass burning (BB)/SOA, sea salt, marine vessels, and vehicle emissions, were apportioned by positive matrix factorization (PMF) as the major sources of ambient organic carbon (OC) in Hong Kong. The secondary formation, including OC from SOA, SS, and aging of BB plume, was the leading contributor to OC (51.4 %, 2.15 ± 1.37 µg C m−3) throughout the year. We then applied a tracer-based method (TBM) to estimate the SOA formation from the photo-oxidation of four selected precursors, and monoterpene SOA was the most abundant. A Kintecus kinetic model was used to examine the formation channels of isoprene SOA, and the aerosol-phase ring-opening reaction of isoprene epoxydiols (IEPOXs) was found to be the dominant formation pathway. Consistently, IEPOX tracers contributed 94 % to total GC–MS-quantified isoprene SOA tracers. The TBM-estimated secondary organic carbon (SOCTBM) and PMF-apportioned SOC (SOCPMF) showed similar temporal trends; however, SOCTBM only accounted for 26.5 % of SOCPMF, indicating a large fraction of ambient SOA was from other reaction pathways or precursors. Results of Pearson's R and multivariate linear regression analysis showed that NOx processing played a key role in both daytime and nighttime SOA production in the region. Moreover, sulfate had a significant positive linear relationship with SOCPMF and SS-related SOC, and particle acidity was significantly correlated with SOC from the aging of BB.


2019 ◽  
Vol 53 (6) ◽  
pp. 3001-3009 ◽  
Author(s):  
Tengyu Liu ◽  
Liyuan Zhou ◽  
Qianyun Liu ◽  
Berto P. Lee ◽  
Dawen Yao ◽  
...  

Chemosphere ◽  
2001 ◽  
Vol 45 (3) ◽  
pp. 315-322 ◽  
Author(s):  
Noureddine Yassaa ◽  
Brahim Youcef Meklati ◽  
Angelo Cecinato ◽  
Fabio Marino

2018 ◽  
Vol 18 (22) ◽  
pp. 16409-16418 ◽  
Author(s):  
Yi Ming Qin ◽  
Hao Bo Tan ◽  
Yong Jie Li ◽  
Zhu Jie Li ◽  
Misha I. Schurman ◽  
...  

Abstract. Light-absorbing organic carbon (or brown carbon, BrC) in atmospheric particles has received much attention for its potential role in global radiative forcing. While a number of field measurement campaigns have differentiated light absorption by black carbon (BC) and BrC, the chemical characteristics of BrC are not well understood. In this study, we present co-located real-time light absorption and chemical composition measurements of atmospheric particles to explore the relationship between the chemical and optical characteristics of BrC at a suburban site downwind of Guangzhou, China, from November to December 2014. BrC and BC contributions to light absorption were estimated using measurements from a seven-wavelength aethalometer, while the chemical composition of non-refractory PM1 was measured with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Using the absorption Ångström exponent (AAE) method, we estimated that BrC contributed 23.6 % to the total aerosol absorption at 370 nm, 18.1 % at 470 nm, 10.7 % at 520 nm, 10.7 % at 590 nm, and 10.5 % at 660 nm. Biomass burning organic aerosol (BBOA) has the highest mass absorption coefficient among sources of organic aerosols. Its contribution to total brown carbon absorption coefficient decreased but that of low-volatility oxygenated organic aerosol (LVOOA) increased with increasing wavelength, suggesting the need for wavelength-dependent light absorption analysis for BrC in association with its chemical makeup. Clear correlations of N-containing ion fragments with absorption coefficient were observed. These correlations also depended on their degrees of unsaturation/cyclization and oxygenation. While the current study relates light absorption by BrC to ion fragments, more detailed chemical characterization is warranted to constrain this relationship.


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