The Finokalia Aerosol Measurement Experiment – 2008 (FAME-08): an overview

Abstract. A month (4 May to 8 June 2008) of ambient aerosol, air ion and gas phase sampling (Finokalia Aerosol Measurement Experiment 2008, FAME-08) was conducted at Finokalia, on the island of Crete, Greece. The purpose of the study was to characterize the physical and chemical properties of aged aerosol and to investigate new particle formation. Measurements included aerosol and air ion size distributions, size-resolved chemical composition, organic aerosol thermal volatility, water uptake and particle optical properties (light scattering and absorption). Statistical analysis of the aerosol mass concentration variations revealed the absence of diurnal patterns suggesting the lack of strong local sources. Sulfates accounted for approximately half of the particulate matter less than 1 micrometer in diameter (PM1) and organics for 26%. The PM1 organic aerosol fraction was highly oxidized with 80% water soluble. The supermicrometer particles were dominated by crustal components (50%), sea salt (24%) and nitrates (16%). The organic carbon to elemental carbon (OC/EC) ratio correlated with ozone measurements but with a one-day lag. The average OC/EC ratio for the study period was equal to 5.4. For three days air masses from North Africa resulted in a 6-fold increase of particulate matter less than 10 micrometers in diameter (PM10) and a decrease of the OC/EC ratio by a factor of 2. Back trajectory analysis, based on FLEXPART footprint plots, identified five source regions (Athens, Greece, Africa, other continental and marine), each of which influenced the PM1 aerosol composition and properties. Marine air masses had the lowest PM1 concentrations and air masses from the Balkans, Turkey and Eastern Europe the highest.

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The Finokalia Aerosol Measurement Experiment – 2008 (FAME-08): an overview

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-6793-2010 ◽

2010 ◽

Vol 10 (14) ◽

pp. 6793-6806 ◽

Cited By ~ 49

Author(s):

M. Pikridas ◽

A. Bougiatioti ◽

L. Hildebrandt ◽

G. J. Engelhart ◽

E. Kostenidou ◽

...

Keyword(s):

Particulate Matter ◽

Organic Aerosol ◽

Water Soluble ◽

Back Trajectory ◽

Aerosol Composition ◽

Air Masses ◽

The Balkans ◽

Aerosol Measurement ◽

Aerosol Mass Concentration ◽

Measurement Experiment

Abstract. A month (4 May to 8 June 2008) of ambient aerosol, air ion and gas phase sampling (Finokalia Aerosol Measurement Experiment 2008, FAME-08) was conducted at Finokalia, on the island of Crete, Greece. The purpose of the study was to characterize the physical and chemical properties of aged aerosol and to investigate new particle formation. Measurements included aerosol and air ion size distributions, size-resolved chemical composition, organic aerosol thermal volatility, water uptake and particle optical properties (light scattering and absorption). Statistical analysis of the aerosol mass concentration variations revealed the absence of diurnal patterns suggesting the lack of strong local sources. Sulfates accounted for approximately half of the particulate matter less than 1 micrometer in diameter (PM1) and organics for 28%. The PM1 organic aerosol fraction was highly oxidized with 80% water soluble. The supermicrometer particles were dominated by crustal components (50%), sea salt (24%) and nitrates (16%). The organic carbon to elemental carbon (OC/EC) ratio correlated with ozone measurements but with a one-day lag. The average OC/EC ratio for the study period was equal to 5.4. For three days air masses from North Africa resulted in a 6-fold increase of particulate matter less than 10 micrometers in diameter (PM10) and a decrease of the OC/EC ratio by a factor of 2. Back trajectory analysis, based on FLEXPART footprint plots, identified five source regions (Athens, Greece, Africa, other continental and marine), each of which influenced the PM1 aerosol composition and properties. Marine air masses had the lowest PM1 concentrations and air masses from the Balkans, Turkey and Eastern Europe the highest.

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Characterization of Aerosol Composition, Aerosol Acidity and Organic Acid Partitioning at an Agriculture-Intensive Rural Southeastern U.S. Site

10.5194/acp-2018-373 ◽

2018 ◽

Cited By ~ 1

Author(s):

Theodora Nah ◽

Hongyu Guo ◽

Amy P. Sullivan ◽

Yunle Chen ◽

David J. Tanner ◽

...

Keyword(s):

Oxalic Acid ◽

Organic Acids ◽

Organic Acid ◽

Organic Aerosol ◽

Water Soluble ◽

Molar Concentration ◽

Particle Phase ◽

Aerosol Composition ◽

Phase Water ◽

Acetic Acids

Abstract. The implementation of stringent emission regulations has resulted in the decline of anthropogenic pollutants including sulfur dioxide (SO2), nitrogen oxides (NOx) and carbon monoxide (CO). In contrast, ammonia (NH3) emissions are largely unregulated, with emissions projected to increase in the future. We present real-time aerosol and gas measurements from a field study conducted in an agricultural-intensive region in the southeastern U.S. during the fall of 2016 to investigate how NH3 affects particle acidity and SOA formation via the gas-particle partitioning of semi-volatile organic acids. Particle water and pH were determined using the ISORROPIA-II thermodynamic model and validated by comparing predicted inorganic HNO3-NO3− and NH3-NH4+ gas-particle partitioning ratios with measured values. Our results showed that despite the high NH3 concentrations (study average 8.1 ± 5.2 ppb), PM1 were highly acidic with pH values ranging from 0.9 to 3.8, and a study-averaged pH of 2.2 ± 0.6. PM1 pH varied by approximately 1.4 units diurnally. Formic and acetic acids were the most abundant gas-phase organic acids, and oxalate was the most abundant particle-phase water-soluble organic acid anion. Measured particle-phase water-soluble organic acids were on average 6 % of the total non-refractory PM1 organic aerosol mass. The measured molar fraction of oxalic acid in the particle phase (i.e., particle-phase oxalic acid molar concentration divided by the total oxalic acid molar concentration) ranged between 47 and 90 % for PM1 pH 1.2 to 3.4. The measured oxalic acid gas-particle partitioning ratios were in good agreement with their corresponding thermodynamic predictions, calculated based on oxalic acid’s physicochemical properties, ambient temperature, particle water and pH. In contrast, gas-particle partitioning of formic and acetic acids were not well predicted for reasons currently unknown. For this study, higher NH3 concentrations relative to what has been measured in the region in previous studies had minor effects on PM1 organic acids and their influence on the overall organic aerosol and PM1 mass concentrations.

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Summertime surface PM<sub>1</sub> aerosol composition and size by source region at the Lampedusa island in the central Mediterranean Sea

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11123-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11123-11142 ◽

Cited By ~ 3

Author(s):

Marc D. Mallet ◽

Barbara D'Anna ◽

Aurélie Même ◽

Maria Chiara Bove ◽

Federico Cassola ◽

...

Keyword(s):

Mediterranean Sea ◽

Ammonium Sulfate ◽

Organic Aerosol ◽

Western Mediterranean ◽

Central Mediterranean ◽

Aerosol Composition ◽

Air Masses ◽

Westerly Winds ◽

Central Mediterranean Sea ◽

The Mediterranean

Abstract. Measurements of aerosol composition and size distributions were taken during the summer of 2013 at the remote island of Lampedusa in the southern central Mediterranean Sea. These measurements were part of the ChArMEx/ADRIMED (Chemistry and Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate) framework and took place during Special Observation Period 1a (SOP-1a) from 11 June to 5 July 2013. From compact time-of-flight aerosol mass spectrometer (cToF-AMS) measurements in the size range below 1 µm in aerodynamic diameter (PM1), particles were predominately comprised of ammonium and sulfate. On average, ammonium sulfate contributed 63 % to the non-refractory PM1 mass, followed by organics (33 %). The organic aerosol was generally very highly oxidized (f44 values were typically between 0.25 and 0.26). The contribution of ammonium sulfate was generally higher than organic aerosol in comparison to measurements taken in the western Mediterranean but is consistent with studies undertaken in the eastern basin. Source apportionment of organics using a statistical (positive matrix factorization) model revealed four factors: a hydrocarbon-like organic aerosol (HOA), a methanesulfonic-acid-related oxygenated organic aerosol (MSA-OOA), a more oxidized oxygenated organic aerosol (MO-OOA) and a less oxidized oxygenated organic aerosol (LO-OOA). The MO-OOA was the dominant factor for most of the campaign (53 % of the PM1 OA mass). It was well correlated with SO42-, highly oxidized and generally more dominant during easterly air masses originating from the eastern Mediterranean and central Europe. The LO-OOA factor had a very similar composition to the MO-OOA factor but was more prevalent during westerly winds, with air masses originating from the Atlantic Ocean, the western Mediterranean and at high altitudes over France and Spain from mistral winds. The MSA-OOA factor contributed an average 12 % to the PM1 OA and was more dominant during the mistral winds. The HOA, representing observed primary organic aerosol, only contributed 8 % of the average PM1 OA during the campaign. Even though Lampedusa is one of the most remote sites in the Mediterranean, PM1 concentrations (10 ± 5 µg m−3) were comparable to those observed in coastal cities and sites closer to continental Europe. Cleaner conditions corresponded to higher wind speeds. Nucleation and growth of new aerosol particles was observed during periods of north-westerly winds. From a climatology analysis from 1999 to 2012, these periods were much more prevalent during the measurement campaign than during the preceding 13 years. These results support previous findings that highlight the importance of different large-scale synoptic conditions in determining the regional and local aerosol composition and oxidation and also suggest that a non-polluted surface atmosphere over the Mediterranean is rare.

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The Pasadena Aerosol Characterization Observatory (PACO): chemical and physical analysis of the Western Los Angeles basin aerosol

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-7417-2011 ◽

2011 ◽

Vol 11 (15) ◽

pp. 7417-7443 ◽

Cited By ~ 80

Author(s):

S. P. Hersey ◽

J. S. Craven ◽

K. A. Schilling ◽

A. R. Metcalf ◽

A. Sorooshian ◽

...

Keyword(s):

Los Angeles ◽

Organic Aerosol ◽

Water Soluble ◽

Organic Mass ◽

Los Angeles Basin ◽

Aerosol Composition ◽

Accumulation Mode ◽

California Institute Of Technology ◽

Aerosol Characterization ◽

Marine Layer

Abstract. The Pasadena Aerosol Characterization Observatory (PACO) represents the first major aerosol characterization experiment centered in the Western/Central Los Angeles Basin. The sampling site, located on the campus of the California Institute of Technology in Pasadena, was positioned to sample a continuous afternoon influx of transported urban aerosol with a photochemical age of 1–2 h and generally free from major local contributions. Sampling spanned 5 months during the summer of 2009, which were broken into 3 regimes on the basis of distinct meteorological conditions. Regime I was characterized by a series of low pressure systems, resulting in high humidity and rainy periods with clean conditions. Regime II typified early summer meteorology, with significant morning marine layers and warm, sunny afternoons. Regime III was characterized by hot, dry conditions with little marine layer influence. Regardless of regime, organic aerosol (OA) is the most significant constituent of nonrefractory submicron Los Angeles aerosol (42, 43, and 55 % of total submicron mass in regimes I, II, and III, respectively). The overall oxidation state remains relatively constant on timescales of days to weeks (O:C = 0.44 ± 0.08, 0.55 ± 0.05, and 0.48 ± 0.08 during regimes I, II, and III, respectively), with no difference in O:C between morning and afternoon periods. Periods characterized by significant morning marine layer influence followed by photochemically favorable afternoons displayed significantly higher aerosol mass and O:C ratio, suggesting that aqueous processes may be important in the generation of secondary aerosol and oxidized organic aerosol (OOA) in Los Angeles. Online analysis of water soluble organic carbon (WSOC) indicates that water soluble organic mass (WSOM) reaches maxima near 14:00–15:00 local time (LT), but the percentage of AMS organic mass contributed by WSOM remains relatively constant throughout the day. Sulfate and nitrate reside predominantly in accumulation mode aerosol, while afternoon SOA production coincides with the appearance of a distinct fine mode dominated by organics. Particulate NH4NO3 and (NH4)2SO4 appear to be NH3-limited in regimes I and II, but a significant excess of particulate NH4+ in the hot, dry regime III suggests less SO42− and the presence of either organic amines or NH4+-associated organic acids. C-ToF-AMS data were analyzed by Positive Matrix Factorization (PMF), which resolved three factors, corresponding to a hydrocarbon-like OA (HOA), semivolatile OOA (SV-OOA), and low-volatility OOA (LV-OOA). HOA appears to be a periodic plume source, while SV-OOA exhibits a strong diurnal pattern correlating with ozone. Peaks in SV-OOA concentration correspond to peaks in DMA number concentration and the appearance of a fine organic mode. LV-OOA appears to be an aged accumulation mode constituent that may be associated with aqueous-phase processing, correlating strongly with sulfate and representing the dominant background organic component. Periods characterized by high SV-OOA and LV-OOA were analyzed by filter analysis, revealing a complex mixture of species during periods dominated by SV-OOA and LV-OOA, with LV-OOA periods characterized by shorter-chain dicarboxylic acids (higher O:C ratio), as well as appreciable amounts of nitrate- and sulfate-substituted organics. Phthalic acid was ubiquitous in filter samples, suggesting that PAH photochemistry may be an important SOA pathway in Los Angeles. Aerosol composition was related to water uptake characteristics, and it is concluded that hygroscopicity is largely controlled by organic mass fraction (OMF). The hygroscopicity parameter κ averaged 0.31 ± 0.08, approaching 0.5 at low OMF and 0.1 at high OMF, with increasing OMF suppressing hygroscopic growth and increasing critical dry diameter for CCN activation (Dd). An experiment-averaged κorg of 0.14 was calculated, indicating that the highly-oxidized organic fraction of aerosol in Los Angeles is appreciably more hygroscopic than previously reported in urban areas. Finally, PACO will provide context for results forthcoming from the CalNex field campaign, which involved ground sampling in Pasadena during the spring and summer of 2010.

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Characterization and source apportionment of organic aerosol at 260 m on a meteorological tower in Beijing, China

10.5194/acp-2017-1039 ◽

2017 ◽

Cited By ~ 1

Author(s):

Wei Zhou ◽

Qingqing Wang ◽

Xiujuan Zhao ◽

Weiqi Xu ◽

Chen Chen ◽

...

Keyword(s):

Coal Combustion ◽

Dominant Role ◽

Ground Level ◽

Organic Aerosol ◽

Back Trajectory ◽

Heating Season ◽

Aerosol Composition ◽

Average Mass ◽

Back Trajectory Analysis ◽

Combustion Emissions

Abstract. Despite extensive efforts into characterization of submicron aerosols at ground level in the megacity of Beijing, our understanding of aerosol sources and processes at high altitudes remains less understood. Here we conducted a three-month real-time measurement of non-refractory submicron aerosol (NR-PM1) species at a height of 260 m from 10 October 2014 to 18 January 2015 using an aerosol chemical speciation monitor. Our results showed a significant change in aerosol composition from non-heating period (NHP) to heating season (HP). Organics and chloride showed clear increases during HP due to coal combustion emissions, while nitrate showed substantial decreases from 28 % to 15–18 %. We also found that NR-PM1 species in heating season can have average mass differences of 30–44 % under similar emission sources yet different meteorological conditions. Multi-linear engine 2 (ME-2) using three primary organic aerosol (OA) factors, i.e., fossil fuel-related OA (FFOA) dominantly from coal combustion emissions, cooking OA (COA), biomass burning OA (BBOA) resolved from ground high-resolution aerosol mass spectrometer measurements as constrains was performed to OA mass spectra of ACSM. Two types of secondary OA (SOA) that were well correlated with nitrate and chloride/CO, respectively, were identified. SOA played a dominant role in OA during all periods at 260 m although the contributions were decreased from 72 % during NHP to 58–64 % during HP. The SOA composition also changed significantly from NHP to HP. While the contribution of oxygenated OA (OOA) was decreased from 56–63 % to 32–40 %, less oxidized OOA (LO-OOA) showed a large increase from 9–16 % to 24–26 %. COA contributed a considerable fraction of OA at high altitude, and the contribution was relatively similar across different periods (10–13 %). In contrast, FFOA showed a large increase during HP due to the influences of coal combustion emissions. We also observed very different OA composition between ground level and 260 m. Particularly, the contributions of COA and BBOA at ground site were nearly twice those at 260 m, while SOA at 260 m was ~ 15–34 % higher than that at ground level. Bivariate polar plots and back trajectory analysis further illustrated the different source regions of OA factors in different seasons.

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Characterization and source apportionment of submicron aerosol with aerosol mass spectrometer during the PRIDE-PRD 2006 campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-6911-2011 ◽

2011 ◽

Vol 11 (14) ◽

pp. 6911-6929 ◽

Cited By ~ 52

Author(s):

R. Xiao ◽

N. Takegawa ◽

M. Zheng ◽

Y. Kondo ◽

Y. Miyazaki ◽

...

Keyword(s):

Organic Carbon ◽

Urban Areas ◽

Organic Aerosol ◽

Water Soluble ◽

Aerosol Formation ◽

Aerosol Mass Spectrometer ◽

Air Masses ◽

Submicron Aerosol ◽

Pmf Model ◽

Aerosol Mass

Abstract. Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8 ± 8.4 μg m−3 and 13.5 ± 8.7 μg m−3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva) ∼200 nm and the second mode occurred at Dva from 300–700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and oxygenated aerosol. The origin of HOA and OOA (the sum of LV-OOA and SV-OOA) has been further confirmed by the statistics that primary organic carbon (POC) and secondary organic carbon (SOC), estimated by the EC tracer method, were closely correlated with HOA and OOA, respectively. The results of the EC tracer method and of the PMF model revealed that primary organic aerosol (POA) constituted ~34–47 % of OA mass and secondary organic aerosol (SOA) constituted ~53–66 % of regional organic aerosol in PRD during summer season. The presence of abundant SOA was consistent with water soluble organic carbon (WSOC) results (accounting for ~60 % of OC on average) by Miyazaki et al. (2009) for the same campaign. OOA correlated well with WSOC at the BG site, indicating that most OOA were water soluble. More specifically, approximately 86 % of LV-OOA and 61 % of SV-OOA were estimated as water soluble species on the basis of carbon content comparison.

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Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

Atmospheric Measurement Techniques ◽

10.5194/amt-9-23-2016 ◽

2016 ◽

Vol 9 (1) ◽

pp. 23-39 ◽

Cited By ~ 57

Author(s):

K. R. Daellenbach ◽

C. Bozzetti ◽

A. Křepelová ◽

F. Canonaco ◽

R. Wolf ◽

...

Keyword(s):

Particulate Matter ◽

Source Apportionment ◽

Organic Aerosol ◽

Transmission Efficiency ◽

Water Soluble ◽

Spatially Resolved ◽

Aerosol Mass ◽

Online Measurements ◽

Rural Sites ◽

Pm2.5 And Pm10

Abstract. Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60–91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

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Measurement of the ambient organic aerosol volatility distribution: application during the Finokalia Aerosol Measurement Experiment (FAME-2008)

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-12149-2010 ◽

2010 ◽

Vol 10 (24) ◽

pp. 12149-12160 ◽

Cited By ~ 61

Author(s):

B. H. Lee ◽

E. Kostenidou ◽

L. Hildebrandt ◽

I. Riipinen ◽

G. J. Engelhart ◽

...

Keyword(s):

Particle Density ◽

Collection Efficiency ◽

Eastern Mediterranean ◽

Organic Aerosol ◽

Accommodation Coefficient ◽

Scanning Mobility Particle Sizer ◽

Aerosol Dynamics ◽

Aerosol Measurement ◽

Measurement Experiment ◽

Particle Sizer

Abstract. A variable residence time thermodenuder (TD) was combined with an Aerodyne Aerosol Mass Spectrometer (AMS) and a Scanning Mobility Particle Sizer (SMPS) to measure the volatility distribution of aged organic aerosol in the Eastern Mediterranean during the Finokalia Aerosol Measurement Experiment in May of 2008 (FAME-2008). A new method for the quantification of the organic aerosol volatility distribution was developed combining measurements of all three instruments together with an aerosol dynamics model. Challenges in the interpretation of ambient thermodenuder-AMS measurements include the potential resistances to mass transfer during particle evaporation, the effects of particle size on the evaporated mass fraction, the changes in the AMS collection efficiency and particle density as the particles evaporate partially in the TD, and finally potential losses inside the TD. Our proposed measurement and data analysis method accounts for all of these problems combining the AMS and SMPS measurements. The AMS collection efficiency of the aerosol that passed through the TD was found to be approximately 10% lower than the collection efficiency of the aerosol that passed through the bypass. The organic aerosol measured at Finokalia is approximately 2 or more orders of magnitude less volatile than fresh laboratory-generated monoterpene (α-pinene, β-pinene and limonene under low NOx conditions) secondary organic aerosol. This low volatility is consistent with its highly oxygenated AMS mass spectrum. The results are found to be highly sensitive to the mass accommodation coefficient of the evaporating species. This analysis is based on the assumption that there were no significant reactions taking place inside the thermodenuder.

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Gas/particle partitioning of water-soluble organic aerosol in Atlanta

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-635-2009 ◽

2009 ◽

Vol 9 (1) ◽

pp. 635-671 ◽

Cited By ~ 2

Author(s):

C. J. Hennigan ◽

M. H. Bergin ◽

A. G. Russell ◽

A. Nenes ◽

R. J. Weber

Keyword(s):

Organic Carbon ◽

Liquid Water ◽

Fine Particle ◽

Mass Concentration ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Water Soluble ◽

Formation Mechanisms ◽

Main Process ◽

Aerosol Mass Concentration

Abstract. Gas and particle-phase organic carbon compounds soluble in water (e.g., WSOC) were measured simultaneously in Atlanta throughout the summer of 2007 to investigate gas/particle partitioning of ambient secondary organic aerosol (SOA). Previous studies have established that, in the absence of biomass burning, particulate WSOC (WSOCp) is mainly from secondary organic aerosol (SOA) production. Comparisons between WSOCp, organic carbon (OC) and elemental carbon (EC) indicate that WSOCp was a nearly comprehensive measure of SOA in the Atlanta summertime. To study SOA formation mechanisms, WSOC gas-particle partitioning was investigated as a function of temperature, RH, NOx, O3, and organic aerosol mass concentration. Identifying a clear temperature effect on partitioning was confounded by other temperature-dependent processes, which likely included the emissions of biogenic SOA precursors and photochemical SOA formation. Relative humidity data indicated a linear dependence between partitioning and fine particle liquid water. Lower NOx concentrations were associated with greater partitioning to particles, but WSOC partitioning had no visible relation to O3 or fine particle OC mass concentration. There was, however, a relationship between WSOC partitioning and the WSOCp concentration, suggesting a compositional dependence between partitioning semi-volatile gases and the phase state of the aerosol. Combined, the overall results suggest that partitioning to liquid water, followed by heterogeneous reactions may represent the main process by which SOA is formed in urban Atlanta during summer.

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Measurement of the ambient organic aerosol volatility distribution: application during the Finokalia Aerosol Measurement Experiment (FAME-2008)

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-17435-2010 ◽

2010 ◽

Vol 10 (7) ◽

pp. 17435-17466 ◽

Cited By ~ 2

Author(s):

B. H. Lee ◽

E. Kostenidou ◽

L. Hildebrandt ◽

I. Riipinen ◽

G. J. Engelhart ◽

...

Keyword(s):

Particle Density ◽

Collection Efficiency ◽

Eastern Mediterranean ◽

Organic Aerosol ◽

Accommodation Coefficient ◽

Scanning Mobility Particle Sizer ◽

Aerosol Dynamics ◽

Aerosol Measurement ◽

Measurement Experiment ◽

Particle Sizer

Abstract. A variable residence time thermodenuder (TD) was combined with an Aerodyne Aerosol Mass Spectrometer (AMS) and a Scanning Mobility Particle Sizer (SMPS) to measure the volatility distribution of aged organic aerosol in the Eastern Mediterranean during the Finokalia Aerosol Measurement Experiment in May of 2008 (FAME-2008). A new method for the quantification of the organic aerosol volatility distribution was developed combining measurements of all three instruments together with an aerosol dynamics model. Challenges in the interpretation of ambient thermodenuder-AMS measurements include the potential resistances to mass transfer during particle evaporation, the effects of particle size on the evaporated mass fraction, the changes in the AMS collection efficiency and particle density as the particles evaporate partially in the TD, and finally potential losses inside the TD. Our proposed measurement and data analysis method accounts for all of these problems combining the AMS and SMPS measurements. The AMS collection efficiency of the aerosol that passed through the TD was found to be approximately 10% lower than the collection efficiency of the aerosol that passed through the bypass. The organic aerosol measured at Finokalia is approximately 2 orders of magnitude less volatile than fresh laboratory-generated biogenic secondary organic aerosol. This low volatility is consistent with its highly oxygenated AMS mass spectrum. The results are found to be highly sensitive to the mass accommodation coefficient of the evaporating species.

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