Evaluating the degree of oxygenation of organic aerosol during foggy and hazy days in Hong Kong using high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS)

Abstract. The chemical characteristics of organic aerosol (OA) are still poorly constrained. Here we present observation results of the degree of oxygenation of OA based on high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) measurements made at a coastal site in Hong Kong from late April to the end of May in 2011. Two foggy periods and one hazy period were chosen for detailed analysis to compare the changes in the degree of oxygenation of OA due to different processes. The Extended Aerosol Inorganic Model (E-AIM) predicted a fine particle liquid water content (LWCfp) up to 85 μg m−3 during the foggy days. Particle concentration as measured by HR-ToF-AMS was up to 60 μg m−3 during the hazy days and up to 30 μg m−3 during the foggy days. The degree of oxygenation of OA, as indicated by several parameters including the fraction of m/z 44 in organic mass spectra (f44), the elemental ratio of oxygen to carbon (O : C), and the carbon oxidation state (OSc), was evaluated against the odd oxygen (Ox) concentration, LWCfp, ionic strength (IS), and in-situ pH (pHis). Results suggest that the high concentration of OA (on average 11 μg m−3) and the high degree of oxygenation (f44 = 0.15, O : C = 0.51, and OSc = −0.31) during the hazy period were mainly due to gas-phase oxidation. During the foggy periods with low photochemical activities, the degree of oxygenation of OA was almost as high as that on the hazy days and significantly higher than that during non-foggy/non-hazy days. However, the OA evolved quite differently in the two foggy periods. The first foggy period in late April saw a larger LWCfp and a lower Ox concentration and the OA was made up of ~ 20% semi-volatile oxygenated organic aerosol (SVOOA) as resolved by positive matrix factorization (PMF). In the second foggy period in mid-May, higher Ox concentration and lower LWCfp were observed, and the OA was found to contain >50% low-volatility oxygenated organic aerosols (LVOOA). An examination of the particle-phase constituents suggests that partitioning may have been the dominating process through which oxygenated species were incorporated into the particle phase during the first foggy period, while oxidation in the aqueous phase may have been the dominating process during the second foggy period. Both physical and chemical processes were found to be important for oxygenated OA formation.

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Evaluating the degree of oxygenation of organic aerosol during foggy and hazy days in Hong Kong using high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS)

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-8739-2013 ◽

2013 ◽

Vol 13 (17) ◽

pp. 8739-8753 ◽

Cited By ~ 45

Author(s):

Y. J. Li ◽

B. Y. L. Lee ◽

J. Z. Yu ◽

N. L. Ng ◽

C. K. Chan

Keyword(s):

Mass Spectrometry ◽

Hong Kong ◽

High Resolution ◽

Gas Phase ◽

Time Of Flight ◽

Organic Aerosol ◽

Resolution Time ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Inorganic Species

Abstract. The chemical characteristics of organic aerosol (OA) are still poorly constrained. Here we present observation results of the degree of oxygenation of OA based on high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) measurements made at a coastal site in Hong Kong from late April to the end of May in 2011. Two foggy periods and one hazy period were chosen for detailed analysis to compare the changes in the degree of oxygenation of OA due to different processes. Using HR-ToF-AMS measured inorganic species as input, the Extended Aerosol Inorganic Model (E-AIM) predicted a fine-particle liquid water content (LWCfp) up to 85 μg m−3 during the foggy days. Particle concentration as measured by HR-ToF-AMS was up to 60 μg m−3 during the hazy days and up to 30 μg m−3 during the foggy days. The degree of oxygenation of OA, as indicated by several parameters including the fraction of m/z 44 in organic mass spectra (f44), the elemental ratio of oxygen to carbon (O : C), and the carbon oxidation state (OSc), was evaluated against the odd oxygen (Ox) concentration, LWCfp, ionic strength (IS), and in situ pH (pHis). Observations suggest that the high concentration of OA (on average 11 μg m−3) and the high degree of oxygenation (f44 = 0.15, O : C = 0.51, and OSc = −0.31) during the hazy period were mainly due to gas-phase oxidation. During the foggy periods with low photochemical activities, the degree of oxygenation of OA was almost as high as that on the hazy days, and significantly higher than that during non-foggy/non-hazy days. However, the OA evolved quite differently in the two foggy periods. The first foggy period in late April saw a larger LWCfp and a lower Ox concentration and the OA were made up of ~ 20 % semi-volatile oxygenated organic aerosol (SVOOA) as resolved by positive matrix factorization (PMF). In the second foggy period in mid-May, higher Ox concentration and lower LWCfp were observed, and the OA were found to contain > 50 % low-volatility oxygenated organic aerosols (LVOOA). An examination of the particle characteristics (pHis, IS, and LWCfp) suggests that partitioning may have been the dominating process through which oxygenated species were incorporated into the particle phase during the first foggy period, while oxidation in the aqueous phase dominated over gas-phase processes during the second foggy period.

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Aerosol Chemical Composition in Cloud Events by High Resolution Time-of-Flight Aerosol Mass Spectrometry

Environmental Science & Technology ◽

10.1021/es302889w ◽

2013 ◽

Vol 47 (6) ◽

pp. 2645-2653 ◽

Cited By ~ 28

Author(s):

Liqing Hao ◽

Sami Romakkaniemi ◽

Aki Kortelainen ◽

Antti Jaatinen ◽

Harri Portin ◽

...

Keyword(s):

Mass Spectrometry ◽

Chemical Composition ◽

High Resolution ◽

Time Of Flight ◽

Resolution Time ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Aerosol Chemical Composition

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O/C and OM/OC Ratios of Primary, Secondary, and Ambient Organic Aerosols with High-Resolution Time-of-Flight Aerosol Mass Spectrometry

Environmental Science & Technology ◽

10.1021/es703009q ◽

2008 ◽

Vol 42 (12) ◽

pp. 4478-4485 ◽

Cited By ~ 1206

Author(s):

Allison C. Aiken ◽

Peter F. DeCarlo ◽

Jesse H. Kroll ◽

Douglas R. Worsnop ◽

J. Alex Huffman ◽

...

Keyword(s):

Mass Spectrometry ◽

High Resolution ◽

Time Of Flight ◽

Organic Aerosols ◽

Resolution Time ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry

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Evaluating the Mixing of Organic Aerosol Components Using High-Resolution Aerosol Mass Spectrometry

Environmental Science & Technology ◽

10.1021/es200825g ◽

2011 ◽

Vol 45 (15) ◽

pp. 6329-6335 ◽

Cited By ~ 36

Author(s):

Lea Hildebrandt ◽

Kaytlin M. Henry ◽

Jesse H. Kroll ◽

Douglas R. Worsnop ◽

Spyros N. Pandis ◽

...

Keyword(s):

Mass Spectrometry ◽

High Resolution ◽

Organic Aerosol ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry

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Characterization of urban aerosol in Cork city (Ireland) using aerosol mass spectrometry

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-4997-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 4997-5015 ◽

Cited By ~ 46

Author(s):

M. Dall'Osto ◽

J. Ovadnevaite ◽

D. Ceburnis ◽

D. Martin ◽

R. M. Healy ◽

...

Keyword(s):

Mass Spectrometry ◽

Mass Spectrometer ◽

Urban Areas ◽

Time Of Flight ◽

Organic Matrix ◽

Organic Aerosol ◽

Abundant Species ◽

Urban Aerosol ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry

Abstract. Ambient wintertime background urban aerosol in Cork city, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC), sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was characterized using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS) and was also found to comprise organic aerosol as the most abundant species (62%), followed by nitrate (15%), sulphate (9%) and ammonium (9%), and chloride (5%). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic aerosol (HOA) comprised 20% of the mass, "low-volatility" oxygenated organic aerosol (LV-OOA) comprised 18%, "biomass burning" organic aerosol (BBOA) comprised 23%, non-wood solid-fuel combustion "peat and coal" organic aerosol (PCOA) comprised 21%, and finally a species type characterized by primary \\textit{m/z}~peaks at 41 and 55, similar to previously reported "cooking" organic aerosol (COA), but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Correlations between the different particle types obtained by the two aerosol mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosol mass and non-refractory total PM1, respectively).

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Characterization of Primary Organic Aerosol Emissions from Meat Cooking, Trash Burning, and Motor Vehicles with High-Resolution Aerosol Mass Spectrometry and Comparison with Ambient and Chamber Observations

Environmental Science & Technology ◽

10.1021/es8011518 ◽

2009 ◽

Vol 43 (7) ◽

pp. 2443-2449 ◽

Cited By ~ 271

Author(s):

Claudia Mohr ◽

J. Alex Huffman ◽

Michael J. Cubison ◽

Allison C. Aiken ◽

Kenneth S. Docherty ◽

...

Keyword(s):

Mass Spectrometry ◽

High Resolution ◽

Organic Aerosol ◽

Motor Vehicles ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Meat Cooking ◽

Aerosol Emissions

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Chemical characterization of secondary organic aerosol at a rural site in the southeastern US: insights from simultaneous high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and FIGAERO chemical ionization mass spectrometer (CIMS) measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-8421-2020 ◽

2020 ◽

Vol 20 (14) ◽

pp. 8421-8440

Author(s):

Yunle Chen ◽

Masayuki Takeuchi ◽

Theodora Nah ◽

Lu Xu ◽

Manjula R. Canagaratna ◽

...

Keyword(s):

High Resolution ◽

Mass Spectrometer ◽

Chemical Ionization ◽

Secondary Organic Aerosol ◽

Time Of Flight ◽

Organic Aerosol ◽

Ionization Mass ◽

Resolution Time ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass

Abstract. The formation and evolution of secondary organic aerosol (SOA) were investigated at Yorkville, GA, in late summer (mid-August to mid-October 2016). The organic aerosol (OA) composition was measured using two online mass spectrometry instruments, the high-resolution time-of-flight aerosol mass spectrometer (AMS) and the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct chemical ionization mass spectrometer (FIGAERO-CIMS). Through analysis of speciated organics data from FIGAERO-CIMS and factorization analysis of data obtained from both instruments, we observed notable SOA formation from isoprene and monoterpenes during both day and night. Specifically, in addition to isoprene epoxydiol (IEPOX) uptake, we identified isoprene SOA formation from non-IEPOX pathways and isoprene organic nitrate formation via photooxidation in the presence of NOx and nitrate radical oxidation. Monoterpenes were found to be the most important SOA precursors at night. We observed significant contributions from highly oxidized acid-like compounds to the aged OA factor from FIGAERO-CIMS. Taken together, our results showed that FIGAERO-CIMS measurements are highly complementary to the extensively used AMS factorization analysis, and together they provide more comprehensive insights into OA sources and composition.

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Direct contribution of ammonia to <i>α</i>-pinene secondary organic aerosol formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-14393-2020 ◽

2020 ◽

Vol 20 (22) ◽

pp. 14393-14405

Author(s):

Liqing Hao ◽

Eetu Kari ◽

Ari Leskinen ◽

Douglas R. Worsnop ◽

Annele Virtanen

Keyword(s):

Chemical Composition ◽

High Resolution ◽

Organic Acids ◽

Gas Phase ◽

Mass Spectrometer ◽

Mass Concentration ◽

Organic Aerosol ◽

Particle Phase ◽

Resolution Time ◽

Aerosol Mass

Abstract. Ammonia (NH3), a gaseous compound ubiquitously present in the atmosphere, is involved in the formation of secondary organic aerosol (SOA), but the exact mechanism is still not well known. This study presents the results of SOA experiments from the photooxidation of α-pinene in the presence of NH3 in the reaction chamber. SOA was formed in in nucleation experiments and in seeded experiments with ammonium sulfate particles as seeds. The chemical composition and time series of compounds in the gas and particle phase were characterized by an online high-resolution time-of-flight proton-transfer-reaction mass spectrometer (HR-ToF-PTRMS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), respectively. Our results show that the mass concentration of ammonium (NH4+) was still rising even after the mass concentration of the organic component started to decrease due to aerosol wall deposition and evaporation, implying the continuous new formation of particle-phase ammonium in the process. Stoichiometric neutralization analysis of aerosol indicates that organic acids have a central role in the formation of particle-phase ammonium. Our measurements show a good correlation between the gas-phase organic mono- and dicarboxylic acids formed in the photooxidation of α-pinene and the ammonium in the particle phase, thus highlighting the contribution of gas-phase organic acids to the ammonium formation. The work shows that the gas-phase organic acids contribute to the SOA formation by forming organic ammonium salts through acid–base reaction. The changes in aerosol mass, particle size and chemical composition resulting from the NH3–SOA interaction can potentially alter the aerosol direct and indirect forcing and therefore alter its impact on climate change.

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