Seasonal variations in chemical characterization of submicron aerosol particles in Shanghai, China: Insights from a high-resolution aerosol mass spectrometry

2020 ◽  
Author(s):  
Wenfei Zhu ◽  
Shengrong Lou ◽  
Song Guo
Keyword(s):  
Particulate Matter ◽  
High Resolution ◽  
Photochemical Reaction ◽  
Chemical Characterization ◽  
Organic Aerosol ◽  
Submicron Particles ◽  
Chemical Components ◽  
Average Mass ◽  
Compound Pollution ◽  
Autumn And Winter

<p>As a characteristic pollutant of urban compound pollution, submicron particulate matter (PM1) has significantly impacted on human health and climate change. In this study, four intensive campaigns using a high-resolution time-of-flight AMS (HR-ToF-AMS) and other online instruments from 2016 to 2017 were conducted to investigate the seasonal characteristics of submicron particles in Shanghai. The average mass concentrations of submicron particulate matter during spring, summer, autumn and winter observations in Shanghai are 23.9 ± 20.7 μg/m3, 28.5 ± 17.6 μg/m3, 22.0 ± 17.2 μg/m3 and 31.9 ± 22.7 μg/m3, respectively. The major chemical components in submicron particulate matter showed obvious seasonal and daily variations. The increase of submicron particulate matter is mainly due to the contribution of nitrate in spring, autumn and winter, while the photochemical reaction promotes the rapid growth of sulfate in summer. Detailed source apportionment of organic aerosol showed that the fraction of more oxidized oxygenated organic aerosol in organic aerosol in spring was much lower than primary organic aerosol. Oxygenated organic aerosol dominated organic aerosol in summer (69%). More oxidized oxygenated organic aerosol account for 28% in autumn, suggesting that organic aerosol was aging. The liquid phase oxidation and the strong photochemical reaction concentration have a significant contribution to the formation of more oxidized oxygenated organic aerosol and less oxidized oxygenated organic aerosol in the spring, summer and winter observations, respectively. However, the photochemical reaction process dominated the formation of more oxidized oxygenated organic aerosol in autumn.</p>

scholarly journals Sources and chemical characterization of organic aerosol during the summer in the eastern Mediterranean

2015 ◽  
Vol 15 (3) ◽  
pp. 3455-3491 ◽  
Author(s):  
E. Kostenidou ◽  
K. Florou ◽  
C. Kaltsonoudis ◽  
M. Tsiflikiotou ◽  
S. Vratolis ◽  
...  
Keyword(s):  
High Resolution ◽  
Eastern Mediterranean ◽  
Fine Particulate Matter ◽  
Chemical Characterization ◽  
Organic Aerosol ◽  
Atomic Ratio ◽  
Photochemical Activity ◽  
Average Mass ◽  
Pollution Levels ◽  
Aerosol Mass

Abstract. The concentration and chemical composition of the non-refractory fine particulate matter (NR-PM1) and black carbon (BC) levels were measured during the summer of 2012 in the suburbs of two Greek cities, Patras and Athens, in an effort to better understand the chemical processing of particles in the high photochemical activity environment of the Eastern Mediterranean. The composition of PM1 was surprisingly similar in both areas demonstrating the importance of regional sources for the corresponding pollution levels. The PM1 average mass concentration was 9–14 μg m−3. The contribution of sulphate was around 38%, while organic aerosol (OA) contributed approximately 45% in both cases. PM1 nitrate levels were low (2%). The oxygen to carbon (O : C) atomic ratio was 0.50 ± 0.08 in Patras and 0.47 ± 0.11 in Athens. In both cases the PM1 was acidic. Positive matrix factorization (PMF) was applied to the high resolution organic aerosol mass spectra obtained by an Aerodyne High Resolution Aerosol Mass Spectrometer (HR-AMS). For Patras five OA sources could be identified: 19% very oxygenated OA (V-OOA), 38% moderately oxygenated OA (M-OOA), 21% biogenic oxygenated OA (b-OOA), 7% hydrocarbon-like OA (HOA-1) associated with traffic sources and 15% hydrocarbon-like OA (HOA-2) related to other primary emissions (including cooking OA). For Athens the corresponding source contributions were: V-OOA (35%), M-OOA (30%), HOA-1 (18%) and HOA-2 (17%). In both cities the major component was OOA, suggesting that under high photochemical conditions most of the OA in the Eastern Mediterranean is quite aged. The contribution of the primary sources (HOA-1 and HOA-2) was important (22% in Patras and 33% in Athens) but not dominant.

scholarly journals Sources and chemical characterization of organic aerosol during the summer in the eastern Mediterranean

2015 ◽  
Vol 15 (19) ◽  
pp. 11355-11371 ◽  
Author(s):  
E. Kostenidou ◽  
K. Florou ◽  
C. Kaltsonoudis ◽  
M. Tsiflikiotou ◽  
S. Vratolis ◽  
...  
Keyword(s):  
High Resolution ◽  
Eastern Mediterranean ◽  
Fine Particulate Matter ◽  
Chemical Characterization ◽  
Organic Aerosol ◽  
Atomic Ratio ◽  
Photochemical Activity ◽  
Average Mass ◽  
Pollution Levels ◽  
Aerosol Mass

Abstract. The concentration and chemical composition of non-refractory fine particulate matter (NR-PM1) and black carbon (BC) levels were measured during the summer of 2012 in the suburbs of two Greek cities, Patras and Athens, in an effort to better understand the chemical processing of particles in the high photochemical activity environment of the eastern Mediterranean. The composition of PM1 was surprisingly similar in both areas, demonstrating the importance of regional sources for the corresponding pollution levels. The PM1 average mass concentration was 9–14 μg m−3. The contribution of sulfate was around 38 %, while organic aerosol (OA) contributed approximately 45 % in both cases. PM1 nitrate levels were low (2 %). The oxygen to carbon (O : C) atomic ratio was 0.50 ± 0.08 in Patras and 0.47 ± 0.11 in Athens. In both cases PM1 was acidic. Positive matrix factorization (PMF) was applied to the high-resolution organic aerosol mass spectra obtained by an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). For Patras, five OA sources could be identified: 19 % very oxygenated OA (V-OOA), 38 % moderately oxygenated OA (M-OOA), 21 % biogenic oxygenated OA (b-OOA), 7 % hydrocarbon-like OA (HOA-1) associated with traffic sources and 15 % hydrocarbon-like OA (HOA-2) related to other primary emissions (including cooking OA). For Athens, the corresponding source contributions were: V-OOA (35 %), M-OOA (30 %), HOA-1 (18 %) and HOA-2 (17 %). In both cities the major component was OOA, suggesting that under high photochemical conditions most of the OA in the eastern Mediterranean is quite aged. The contribution of the primary sources (HOA-1 and HOA-2) was important (22 % in Patras and 35 % in Athens) but not dominant.

scholarly journals Primary emissions versus secondary formation of fine particulate matter in the most polluted city (Shijiazhuang) in North China

2019 ◽  
Vol 19 (4) ◽  
pp. 2283-2298 ◽  
Author(s):  
Ru-Jin Huang ◽  
Yichen Wang ◽  
Junji Cao ◽  
Chunshui Lin ◽  
Jing Duan ◽  
...  
Keyword(s):  
Particulate Matter ◽  
North China ◽  
Fine Particulate Matter ◽  
Mass Range ◽  
Organic Aerosol ◽  
Average Mass ◽  
Episodic Events ◽  
Secondary Formation ◽  
Primary Emissions ◽  
Pollution Events

Abstract. Particulate matter (PM) pollution is a severe environmental problem in the Beijing–Tianjin–Hebei (BTH) region in North China. PM studies have been conducted extensively in Beijing, but the chemical composition, sources, and atmospheric processes of PM are still relatively less known in nearby Tianjin and Hebei. In this study, fine PM in urban Shijiazhuang (the capital of Hebei Province) was characterized using an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) from 11 January to 18 February in 2014. The average mass concentration of non-refractory submicron PM (diameter <1 µm, NR-PM1) was 178±101 µg m−3, and it was composed of 50 % organic aerosol (OA), 21 % sulfate, 12 % nitrate, 11 % ammonium, and 6 % chloride. Using the multilinear engine (ME-2) receptor model, five OA sources were identified and quantified, including hydrocarbon-like OA from vehicle emissions (HOA, 13 %), cooking OA (COA, 16 %), biomass burning OA (BBOA, 17 %), coal combustion OA (CCOA, 27 %), and oxygenated OA (OOA, 27 %). We found that secondary formation contributed substantially to PM in episodic events, whereas primary emissions were dominant (most significant) on average. The episodic events with the highest NR-PM1 mass range of 300–360 µg m−3 were comprised of 55 % of secondary species. On the contrary, a campaign-average low OOA fraction (27 %) in OA indicated the importance of primary emissions, and a low sulfur oxidation degree (FSO4) of 0.18 even at RH >90 % hinted at insufficient oxidation. These results suggested that in Shijiazhuang in wintertime fine PM was mostly from primary emissions without sufficient atmospheric aging, indicating opportunities for air quality improvement by mitigating direct emissions. In addition, secondary inorganic and organic (OOA) species dominated in pollution events with high-RH conditions, most likely due to enhanced aqueous-phase chemistry, whereas primary organic aerosol (POA) dominated in pollution events with low-RH and stagnant conditions. These results also highlighted the importance of meteorological conditions for PM pollution in this highly polluted city in North China.

scholarly journals Insights on organic aerosol aging and the influence of coal combustion at a regional receptor site of Central Eastern China

2013 ◽  
Vol 13 (4) ◽  
pp. 10809-10858 ◽  
Author(s):  
W. W. Hu ◽  
M. Hu ◽  
B. Yuan ◽  
J. L. Jimenez ◽  
Q. Tang ◽  
...  
Keyword(s):  
High Resolution ◽  
Black Carbon ◽  
Coal Combustion ◽  
Eastern China ◽  
Organic Aerosols ◽  
Receptor Site ◽  
Organic Aerosol ◽  
Submicron Particles ◽  
Central Eastern ◽  
Photochemical Age

Abstract. In order to understand the aging and processing of organic aerosols (OA), an intensive field campaign (Campaign of Air Pollution at Typical Coastal Areas In Eastern China, CAPTAIN) was conducted in March–April at a receptor site (Changdao Island) in Central Eastern China. Multiple fast aerosol and gas measurement instruments were used during the campaign, including a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was applied to measure mass concentrations and non-refractory chemical components of submicron particles (PM1nr). The average mass concentration of PM1 (PM1nr + black carbon) was 47 ± 36 μg m−3 during the campaign and showed distinct variation depending on back trajectories and their overlap with source regions. Organic aerosol (OA) is the largest component of PM1 (30%), followed by nitrate (28%), sulfate (19%), ammonium (15%), black carbon (6%), and chloride (3%). Four OA components were resolved by Positive Matrix Factorization (PMF) of the high-resolution spectra, including low-volatility oxygenated organic aerosol (LV-OOA), semi-volatile oxygenated OA (SV-OOA), hydrocarbon-like OA (HOA) and a coal combustion OA (CCOA), reported here for the first time. The mass spectrum of CCOA has high abundance of fragments from polycyclic aromatic hydrocarbons (PAHs) (m/z 128, 152, 178 etc.). The average atomic ratio of oxygen to carbon in OA (O/C) at Changdao is 0.59, which is comparable to other field studies reported at locations downwind of large pollution sources, indicating the oxidized nature of most OA during the campaign. The evolution of OA elemental composition in the Van Krevelen diagram (H/C vs. O/C) shows a slope of −0.63, however, the OA influenced by coal combution exhibits a completely different evolution that appears dominated by physical mixing. The aging of organic aerosols vs. with photochemical age was investigated. It is shown that OA/ΔCO, as well as LV-OOA/ΔCO and SV-OOA/ΔCO, positively correlated with photochemical age. LV-OOA accounted for 73% of the OA secondary formation in the oldest plumes (photochemical age of 25 h). The kOH at Changdao by assuming SOA formation and aging as a first-order process proportional to OH was calculated to be is 5.2 × 10−12 cm3 molec−1 s−1 which is similar to those determined in recent studies of polluted air in other continents.

scholarly journals Insights on organic aerosol aging and the influence of coal combustion at a regional receptor site of central eastern China

2013 ◽  
Vol 13 (19) ◽  
pp. 10095-10112 ◽  
Author(s):  
W. W. Hu ◽  
M. Hu ◽  
B. Yuan ◽  
J. L. Jimenez ◽  
Q. Tang ◽  
...  
Keyword(s):  
High Resolution ◽  
Black Carbon ◽  
Coal Combustion ◽  
Eastern China ◽  
Organic Aerosols ◽  
Receptor Site ◽  
Organic Aerosol ◽  
Submicron Particles ◽  
Central Eastern ◽  
Photochemical Age

Abstract. In order to understand the aging and processing of organic aerosols (OA), an intensive field campaign (Campaign of Air Pollution at Typical Coastal Areas IN Eastern China, CAPTAIN) was conducted March–April at a receptor site (a Changdao island) in central eastern China. Multiple fast aerosol and gas measurement instruments were used during the campaign, including a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) that was applied to measure mass concentrations and non-refractory chemical components of submicron particles (PM1nr). The average mass concentration of PM1(PM1nr+black carbon) was 47 ± 36 μg m−3 during the campaign and showed distinct variation, depending on back trajectories and their overlap with source regions. Organic aerosol (OA) is the largest component of PM1 (30%), followed by nitrate (28%), sulfate (19%), ammonium (15%), black carbon (6%), and chloride (3%). Four OA components were resolved by positive matrix factorization (PMF) of the high-resolution spectra, including low-volatility oxygenated organic aerosol (LV-OOA), semi-volatile oxygenated OA (SV-OOA), hydrocarbon-like OA (HOA) and a coal combustion OA (CCOA). The mass spectrum of CCOA had high abundance of fragments from polycyclic aromatic hydrocarbons (PAHs) (m/z 128, 152, 178, etc.). The average atomic ratio of oxygen to carbon in OA (O / C) at Changdao was 0.59, which is comparable to other field studies reported at locations downwind of large pollution sources, indicating the oxidized nature of most OA during the campaign. The evolution of OA elemental composition in the van Krevelen diagram (H / C vs. O / C) showed a slope of −0.63; however, the OA influenced by coal combustion exhibits a completely different evolution that appears dominated by physical mixing. The aging of organic aerosols vs. photochemical age was investigated. It was shown that OA / ΔCO, as well as LV-OOA / ΔCO and SV-OOA / ΔCO, positively correlated with photochemical age. LV-OOA accounted for 73% of the OA secondary formation (SOA) in the oldest plumes (photochemical age of 25 h). The kOH at Changdao, by assuming SOA formation and aging as a first-order process proportional to OH, was calculated to be 5.2 × 10−12 cm3 molec.−1 s−1, which is similar to those determined in recent studies of polluted air in other continents.

scholarly journals Influence of biomass burning from South Asia at a high-altitude mountain receptor site in China

2017 ◽  
Vol 17 (11) ◽  
pp. 6853-6864 ◽  
Author(s):  
Jing Zheng ◽  
Min Hu ◽  
Zhuofei Du ◽  
Dongjie Shang ◽  
Zhaoheng Gong ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
South Asia ◽  
Biomass Burning ◽  
Monsoon Season ◽  
Organic Aerosol ◽  
Submicron Particles ◽  
The Tibetan Plateau ◽  
Anthropogenic Aerosols ◽  
Air Masses ◽  
Average Mass

Abstract. Highly time-resolved in situ measurements of airborne particles were conducted at Mt. Yulong (3410 m above sea level) on the southeastern edge of the Tibetan Plateau in China from 22 March to 14 April 2015. The detailed chemical composition was measured by a high-resolution time-of-flight aerosol mass spectrometer together with other online instruments. The average mass concentration of the submicron particles (PM1) was 5.7 ± 5.4 µg m−3 during the field campaign, ranging from 0.1 up to 33.3 µg m−3. Organic aerosol (OA) was the dominant component in PM1, with a fraction of 68 %. Three OA factors, i.e., biomass burning organic aerosol (BBOA), biomass-burning-influenced oxygenated organic aerosol (OOA-BB) and oxygenated organic aerosol (OOA), were resolved using positive matrix factorization analysis. The two oxygenated OA factors accounted for 87 % of the total OA mass. Three biomass burning events were identified by examining the enhancement of black carbon concentrations and the f60 (the ratio of the signal at m∕z 60 from the mass spectrum to the total signal of OA). Back trajectories of air masses and satellite fire map data were integrated to identify the biomass burning locations and pollutant transport. The western air masses from South Asia with active biomass burning activities transported large amounts of air pollutants, resulting in elevated organic concentrations up to 4-fold higher than those of the background conditions. This study at Mt. Yulong characterizes the tropospheric background aerosols of the Tibetan Plateau during pre-monsoon season and provides clear evidence that the southeastern edge of the Tibetan Plateau was affected by the transport of anthropogenic aerosols from South Asia.

scholarly journals On the chemical nature of the oxygenated organic aerosol: implication in the formation and aging of α-pinene SOA in a Mediterranean environment, Marseille

2012 ◽  
Vol 12 (8) ◽  
pp. 19769-19797 ◽  
Author(s):  
I. El Haddad ◽  
B. D'Anna ◽  
B. Temime-Roussel ◽  
M. Nicolas ◽  
A. Boreave ◽  
...  
Keyword(s):  
Major Ions ◽  
Chemical Characterization ◽  
High Volume ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Submicron Particles ◽  
Industrial Emissions ◽  
Fossil Carbon ◽  
Aerosol Mass ◽  
Organic Markers

Abstract. Organic Aerosol (OA) measurements were conducted during summer 2008 at an urban background site, in Marseille, France's second city and the largest port in the Mediterranean, an urban industrialized environment known for its active photochemistry. PM2.5 was collected using high volume samplers and analyzed for elemental and organic carbon, major ions (NH4+, NO3− and SO42−), humic-like-substances, organic markers (i.e. primary tracers and α-pinene oxidation products), elemental composition and radiocarbon content (14C). The real-time chemical characterization of submicron particles was also achieved using a compact time of flight aerosol mass spectrometer. Positive matrix factorization conducted on the organic aerosol mass spectra matrix revealed four factors, including traffic emissions (hydrocarbon-like OA, HOA), industrial emissions, semi-volatile (SV-OOA) and low-volatile (LV-OOA) oxygenated organic aerosol (OOA) related to oxidation processes. The results obtained were in excellent agreement with chemical mass balance source apportionments conducted in conjunction with organic markers and elements. It appears that while primary emissions contributed only 22% to the total OA (of which 23% was associated with industrial processes), OOA constituted the overwhelming fraction. Radiocarbon measurements suggest that about 80% of this fraction was of non-fossil origin, assigned predominantly to biogenic secondary organic aerosol. Non-fossil carbon appears to especially dominate the LV-OOA fraction, an aged long-range-transported OOA, marginally affected by local anthropogenic SOA. We also examined the relation between OOA and α-pinene SOA obtained based on the levels of α-pinene oxidation products. α-pinene SOA showed good correlation with SV-OOA, suggesting that the compounds used for estimating α-pinene SOA appear to pertain mainly to the moderately oxidized fraction. In contrast, LV-OOA was found to be intimately related to HUmic LIke substances (HULIS), meaning that these two fractions arise from the same oxidation pathways and share a similar chemical composition (i.e. poly-carboxylic species). A thorough analysis of α-pinene individual oxidation products showed that aging can heavily impact their respective concentrations, as early generation products seem to decay with photochemistry when more oxidized compounds seem to be formed.

scholarly journals Influence of biomass burning from Southeast Asia at a high-altitude mountain receptor site in China

2017 ◽  
Author(s):  
Jing Zheng ◽  
Min Hu ◽  
Zhuofei Du ◽  
Dongjie Shang ◽  
Zhaoheng Gong ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Southeast Asia ◽  
Biomass Burning ◽  
Monsoon Season ◽  
Organic Aerosol ◽  
Submicron Particles ◽  
The Tibetan Plateau ◽  
Anthropogenic Aerosols ◽  
Back Trajectories ◽  
Average Mass

Abstract. Highly time-resolved in-situ measurements of airborne particles were made at Mt. Yulong (3410 m above sea level) on the southeastern edge of the Tibetan Plateau in China from 20 March to 14 April in 2015. Detailed chemical composition was measured by a high-resolution time-of-flight aerosol mass spectrometer together with other online instruments. Average mass concentration of the submicron particles (PM1) was 5.7 ± 5.4 μg m−3 during the field campaign, ranging from 0.1 μg m−3 up to 33.3 μg m−3. Organic aerosol (OA) was the dominant component in PM1, with a fraction of 68 %. Three OA factors, i.e., biomass-burning organic aerosol (BBOA), biomass-burning-influenced oxygenated organic aerosol (OOA-BB) and oxygenated organic aerosol (OOA), were resolved using positive matrix factorization analysis. The two oxygenated OA factors accounted for 87 % of the total OA mass. Three biomass burning events were identified by examining the enhancement of black carbon concentrations and the f60 (the ratio of the signal at m/z 60 from the mass spectrum to the total signal of OA). Back trajectories of air masses and satellite fire map data were integrated to identify the biomass burning locations and pollutants transport. The western air mass from Southeast Asia with active biomass burning activities transported large amount of air pollutants, resulting in elevated organic concentrations up to 4-fold higher than that of the background condition. This study at Mt. Yulong characterizes the tropospheric background aerosols of the Tibetan Plateau during pre-monsoon season, and provides clear evidence that the southeastern edge of the Tibetan Plateau is affected by transport of anthropogenic aerosols from Southeast Asia.

scholarly journals Seasonal variations of high time-resolved chemical compositions, sources and evolution for atmospheric submicron aerosols in the megacity Beijing

2017 ◽  
Author(s):  
Wei Hu ◽  
Min Hu ◽  
Wei-Wei Hu ◽  
Jing Zheng ◽  
Chen Chen ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fine Particles ◽  
Urban Site ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Average Mass ◽  
Four Seasons ◽  
Secondary Formation ◽  
Autumn And Winter

Abstract. Severe regional haze problem in the megacity Beijing and surrounding areas, caused by fast formation and growth of fine particles, has attracted much attention in recent years. In order to investigate the secondary formation and aging process of urban aerosols, four intensive campaigns were conducted in four seasons between March 2012 and March 2013 at an urban site in Beijing (116.31° E, 37.99° N). An Aerodyne high resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) and other relevant instrumentations for gaseous and particulate pollutants were deployed. The average mass concentrations of submicron particulate matter (PM1) were 45.1±45.8, 37.5±31.0, 41.3±42.7, and 81.7±72.4 μg m−3 in spring, summer, autumn and winter, respectively. Organic aerosol (OA) was the most abundant component in PM1, accounting for 31, 33, 44 and 36 % seasonally, and secondary inorganic aerosol (SNA, sum of sulfate, nitrate and ammonium) accounted for 59, 57, 43, and 55 % of PM1 correspondingly. Based on the application of positive matrix factorization (PMF), the sources of OA were obtained, including the primary ones of hydrocarbon-like (HOA), cooking (COA), biomass burning OA (BBOA) and coal combustion OA (CCOA), and secondary component oxygenated OA (OOA). OOA, usually composed of more-oxidized (MO-OOA) and less-oxidized OOA (LO-OOA), accounted for 63, 69, 47 and 50 % in four seasons, respectively. Totally, the fraction of secondary components (OOA+SNA) contributed about 60–80 % to PM1, suggesting that secondary formation played an important role in the PM pollution in Beijing, and primary sources were also non-negligible. The evolution process of OA in different seasons was investigated with multiple metrics and tools. The average carbon oxidation states and other metrics show that the oxidation state of OA was the highest in summer, probably due to both strong photochemical and aqueous-phase oxidations. BBOA and CCOA were only resolved in autumn and winter, respectively, consistent with the agricultural activities (e.g., straw burning after the harvest in suburban areas) in autumn and domestic heating in winter, signifying that the comprehensive management for the emissions from biomass burning and coal combustion are needed. High concentrations of chemical components in PM1 in Beijing, especially in winter or in adverse meteorological conditions, suggest that further strengthening the regional emission control of primary particulate and precursors of secondary species is expected.

scholarly journals Sources and atmospheric processing of wintertime aerosols in Seoul, Korea: Insights from real-time measurements using a high-resolution aerosol mass spectrometer

2016 ◽  
Author(s):  
Hwajin Kim ◽  
Qi Zhang ◽  
Gwi-Nam Bae ◽  
Jin Young Kim ◽  
Seung Bok Lee
Keyword(s):  
Particulate Matter ◽  
High Resolution ◽  
Real Time ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Meteorological Conditions ◽  
Emission Sources ◽  
Aerosol Mass Spectrometer ◽  
Atmospheric Processes ◽  
Aerosol Mass

Abstract. Highly time-resolved chemical characterization of non-refractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital and largest metropolis of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter, when elevated particulate matter (PM) pollution events are often observed. This is the first time that detailed real-time aerosol measurement results are reported from Seoul, Korea, which reveal valuable insights into the sources and atmospheric processes that contribute to PM pollution in this region. The average concentration of submicron aerosol (PM1 = NR - PM1 + black carbon (BC)) was 27.5 µg m−3, and the total mass was dominated by organics (44 %), followed by nitrate (24 %) and sulfate (10 %). The average atomic ratios of oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), and nitrogen-to-carbon (N / C) of organic aerosol (OA) were 0.37, 1.79, and 0.022, respectively, which gives that average organic mass-to-carbon (OM / OC) ratio of 1.67. The concentrations (2.6–90.7 µg m−3) and composition of PM1 varied dynamically during the measurement period, due to the influences of different meteorological conditions, emission sources, and air mass origins. Five distinct sources of OA were identified via positive matrix factorization (PMF) analysis of the HR-ToF-AMS data: vehicle emissions represented by a hydrocarbon like OA factor (HOA; O / C = 0.06), cooking activities represented by a cooking OA factor (COA; O / C = 0.15), wood combustion represented by a biomass burning OA factor (BBOA; O / C = 0.34), and secondary organic aerosol (SOA) represented by a semi-volatile oxygenated OA factor (SV-OOA; O / C = 0.56) and a low volatility oxygenated OA factor (LV-OOA; O / C = 0.68). On average, primary OA (POA = HOA + COA + BBOA) accounted for 59 % the OA mass whereas SV-OOA and LV-OOA contributed 15 % and 26 %, respectively. Our results indicate that air quality in Seoul during winter is influenced strongly by secondary aerosol formation with sulfate, nitrate, ammonium, SV-OOA, and LV-OOA together accounting for 64 % of the PM1 mass during this study. However, aerosol sources and composition were found to be significantly different between clean and polluted periods. During stagnant periods with low wind speed (WS) and high relative humidity (RH), PM concentration was generally high (average ± 1σ = 43.6 ± 12.4 µg m−3) with enhanced fractions of nitrate (27 %) and SV-OOA (8 %), which suggested a strong influence from local production of secondary aerosol. Low PM loading periods (12.6 ± 7.1 µg m−3) tended to occurred under higher WS and lower RH conditions and appeared to be more strongly influenced by regional air masses, as indicated by higher mass fractions of sulfate (12 %) and LV-OOA (21 %) in PM1. Overall, our results indicate that PM pollutants in urban Korea originate from complex emission sources and atmospheric processes and that their concentrations and composition are controlled by various factors including meteorological conditions, local anthropogenic emissions, and upwind sources.

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