scholarly journals A missing source of aerosols in Antarctica – beyond long-range transport, phytoplankton, and photochemistry

2017 ◽  
Vol 17 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Michael R. Giordano ◽  
Lars E. Kalnajs ◽  
Anita Avery ◽  
J. Douglas Goetz ◽  
Sean M. Davis ◽  
...  
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Real Time ◽  
Mass Spectrometer ◽  
Formation Mechanisms ◽  
Second Phase ◽  
Austral Spring ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
The Antarctic

Abstract. Understanding the sources and evolution of aerosols is crucial for constraining the impacts that aerosols have on a global scale. An unanswered question in atmospheric science is the source and evolution of the Antarctic aerosol population. Previous work over the continent has primarily utilized low temporal resolution aerosol filters to answer questions about the chemical composition of Antarctic aerosols. Bulk aerosol sampling has been useful in identifying seasonal cycles in the aerosol populations, especially in populations that have been attributed to Southern Ocean phytoplankton emissions. However, real-time, high-resolution chemical composition data are necessary to identify the mechanisms and exact timing of changes in the Antarctic aerosol. The recent 2ODIAC (2-Season Ozone Depletion and Interaction with Aerosols Campaign) field campaign saw the first ever deployment of a real-time, high-resolution aerosol mass spectrometer (SP-AMS – soot particle aerosol mass spectrometer – or AMS) to the continent. Data obtained from the AMS, and a suite of other aerosol, gas-phase, and meteorological instruments, are presented here. In particular, this paper focuses on the aerosol population over coastal Antarctica and the evolution of that population in austral spring. Results indicate that there exists a sulfate mode in Antarctica that is externally mixed with a mass mode vacuum aerodynamic diameter of 250 nm. Springtime increases in sulfate aerosol are observed and attributed to biogenic sources, in agreement with previous research identifying phytoplankton activity as the source of the aerosol. Furthermore, the total Antarctic aerosol population is shown to undergo three distinct phases during the winter to summer transition. The first phase is dominated by highly aged sulfate particles comprising the majority of the aerosol mass at low wind speed. The second phase, previously unidentified, is the generation of a sub-250 nm aerosol population of unknown composition. The second phase appears as a transitional phase during the extended polar sunrise. The third phase is marked by an increased importance of biogenically derived sulfate to the total aerosol population (photolysis of dimethyl sulfate and methanesulfonic acid (DMS and MSA)). The increased importance of MSA is identified both through the direct, real-time measurement of aerosol MSA and through the use of positive matrix factorization on the sulfur-containing ions in the high-resolution mass-spectral data. Given the importance of sub-250 nm particles, the aforementioned second phase suggests that early austral spring is the season where new particle formation mechanisms are likely to have the largest contribution to the aerosol population in Antarctica.

scholarly journals A missing source of aerosols in Antarctica – beyond long-range transport, phytoplankton, and photochemistry

2016 ◽  
Author(s):  
Michael R. Giordano ◽  
Lars E. Kalnajs ◽  
Anita Avery ◽  
James D. Goetz ◽  
Sean M. Davis ◽  
...  
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Dimethyl Sulfate ◽  
Methanesulfonic Acid ◽  
Global Scale ◽  
Formation Mechanisms ◽  
Second Phase ◽  
Aerosol Sampling ◽  
Austral Spring ◽  
The Antarctic

Abstract. Understanding the sources and evolution of aerosols is crucial for constraining the impacts that aerosols have on a global scale. An unanswered question in atmospheric science is the source and evolution of the Antarctic aerosol population. Previous work over the continent has primarily utilized low resolution aerosol filters (coupled with off-line ion chromatography) to answer questions about Antarctic aerosols. Bulk aerosol sampling has been useful in identifying seasonal cycles in the aerosol populations, especially in populations that have been attributed to Southern Ocean phytoplankton emissions. However, real-time, high resolution chemical composition data is necessary to identify the mechanisms and exact timing of changes in the Antarctic aerosol populations. The recent 2ODIAC (2-Season Ozone Depletion and Interaction with Aerosols Campaign) field campaign saw the first ever deployment of a real-time, high resolution aerosol mass spectrometer (SP-AMS or AMS) to the continent. Data obtained from the AMS, and a suite of other aerosol, gas-phase, and meteorological instruments, are presented here. In particular, this manuscript focuses on the aerosol population over coastal Antarctica and the evolution of that population in Austral Spring. Results indicate that there exists a sulfate mode in Antarctica that is externally mixed to the rest of the aerosol population with a mass mode vacuum aerodynamic diameter of 250 nm. Springtime increases in sulfate aerosol are observed and attributed to biogenic sources, in agreement with previous research identifying phytoplankton activity as the source of the aerosol. Furthermore, the total Antarctic aerosol population is shown to undergo three distinct phases during the winter to summer transition. The first phase is dominated by highly aged sulfate particles comprising the majority of the aerosol population at low wind speed. The second phase, previously unidentified, is the generation of a sub-250 nm aerosol population of unknown composition. The second phase appears as a transitional phase during the extended polar sunrise. The third phase is marked by an increased importance of biogenically-derived sulfate to the total aerosol population (photolysis of dimethyl sulfate and methanesulfonic acid [DMS and MSA]). The increased importance of MSA is identified both through the direct, real-time measurement of aerosol MSA and through the use of positive matrix factorization on the sulfur containing ions in the high-resolution mass spectral data. Given the importance of sub-250 nm particles, the aforementioned second phase suggests that early Austral spring is the season where new particle formation mechanisms are likely to have the largest contribution to the aerosol population in Antarctica.

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

2017 ◽  
Vol 17 (3) ◽  
pp. 2009-2033 ◽  
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 ◽  
Meteorological Conditions ◽  
Emission Sources ◽  
Aerosol Mass Spectrometer ◽  
Secondary Aerosol ◽  
Atmospheric Processes ◽  
Aerosol Mass

Abstract. Highly time-resolved chemical characterization of nonrefractory 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 have been reported from Seoul, Korea, and they 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 aerosols (OA) were 0.37, 1.79, and 0.018, respectively, which result in an 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  =  0.14), wood combustion represented by a biomass burning OA factor (BBOA, O / C  =  0.34), and secondary organic aerosol (SOA) represented by a semivolatile 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 occur 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 (20 %) 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.

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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