A new source of oxygenated organic aerosol and oligomers

Abstract. A large oxygenated organic uptake to aerosols was observed when exposing ambient urban air to inorganic acidic and non-acidic sulfate seed aerosol. For non-acidic seed aerosol the uptake was attributed to the direct dissolution of primary vehicle exhaust gases into the aqueous aerosol fraction, and was correlated to the initial seed sulphate mass. The uptake of primary oxygenated organic gases to aerosols in this study represents a significant amount of organic aerosol (OA) that may be considered primary when compared to that reported for primary organic aerosol (POA), but is considerably more oxygenated (O : C ~ 0.3) than traditional POA. Consequently, a fraction of measured ambient oxygenated OA, which correlates with secondary sulphate, may in fact be of a primary, rather than secondary source. These results represent a new source of oxygenated OA on neutral aerosol and imply that the uptake of primary organic gases will occur in the ambient atmosphere, under dilute conditions, and in the presence of pre-existing SO4 aerosols which contain water. Conversely, under acidic seed aerosol conditions, oligomer formation was observed with the uptake of organics being enhanced by a factor of three or more compared to neutral aerosols, and in less than 2 min, representing an additional source of SOA to the atmosphere. This resulted in a trajectory in Van Krevelen space towards higher O : C (slope ~ −1.5), despite a lack of continual gas-phase oxidation in this closed system. The results demonstrate that high molecular weight species will form on acidic aerosols at the ambient level and mixture of organic gases, but are otherwise unaffected by subsequent aerosol neutralization, and that aerosol acidity will affect the organic O : C via aerosol-phase reactions. These two processes, forming oxygenated POA under neutral conditions and SOA under acidic conditions can contribute to the total ambient OA mass and the evolution of ambient aerosol O : C ratios. This may be important for properly representing organic aerosol O : C ratios in air quality and climate models.

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A new source of oxygenated organic aerosol and oligomers

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-29069-2012 ◽

2012 ◽

Vol 12 (11) ◽

pp. 29069-29098

Author(s):

J. Liggio ◽

S.-M. Li

Keyword(s):

Climate Models ◽

Organic Aerosol ◽

Secondary Source ◽

Ambient Atmosphere ◽

Vehicle Exhaust ◽

Aerosol Acidity ◽

Acidic Conditions ◽

Initial Seed ◽

Organic Gases ◽

Seed Aerosol

Abstract. A large oxygenated organic uptake to aerosols was observed when exposing ambient urban air to inorganic acidic and non-acidic sulfate seed aerosol. For non-acidic seed aerosol the uptake was attributed to the direct condensation of primary vehicle exhaust gases, and was correlated to the initial seed sulfate mass. The uptake of primary oxygenated organic gases to aerosols in this study represents a significant amount of organic aerosol (OA) when compared to that reported for primary organic aerosol (POA), but is considerably more oxygenated (O : C ~ 0.3) than traditional POA. Consequently, a fraction of measured ambient oxygenated OA, which correlate with secondary sulfate, may in fact be of a primary, rather than secondary source. These results represent a new source of oxygenated OA on neutral aerosol and imply that the uptake of primary organic gases will occur in the ambient atmosphere, under dilute conditions, and in the presence of pre-existing SO4 aerosols. Under acidic seed aerosol conditions, oligomer formation was observed with the uptake of organics being enhanced by a factor of three or more compared to neutral aerosols, and in less than 2 min. This resulted in a trajectory in Van Krevelen space towards higher O : C (slope ~ −1.5), despite a lack of continual gas-phase oxidation in this closed system. The results demonstrate that high molecular weight species will form on acidic aerosols at the ambient level and mixture of organic gases, but are otherwise unaffected by subsequent aerosol neutralization, and that aerosol acidity will affect the organic O : C via aerosol-phase reactions. These new processes under both neutral and acidic conditions can contribute to ambient OA mass and the evolution of ambient aerosol O : C ratios and may be important for properly representing organic aerosol O : C ratios in air quality and climate models.

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Light absorption by secondary organic aerosol fromα-pinene: Effects of oxidants, seed aerosol acidity, and relative humidity

Journal of Geophysical Research Atmospheres ◽

10.1002/jgrd.50767 ◽

2013 ◽

Vol 118 (20) ◽

pp. 11,741-11,749 ◽

Cited By ~ 26

Author(s):

Chen Song ◽

Madhu Gyawali ◽

Rahul A. Zaveri ◽

John E. Shilling ◽

W. Patrick Arnott

Keyword(s):

Relative Humidity ◽

Light Absorption ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Aerosol Acidity ◽

Seed Aerosol

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Heterogeneous uptake of NH3 on ambient PM2.5 in Beijing and Shijiazhuang: Possible influence of aerosol acidity

10.5194/egusphere-egu21-8105 ◽

2021 ◽

Author(s):

Yongchun Liu ◽

Zeming Feng ◽

Junlei Zhan ◽

Xiaolei Bao

Keyword(s):

Sulfuric Acid ◽

Organic Aerosol ◽

Uptake Coefficient ◽

Natural Ecosystems ◽

Aerosol Acidity ◽

Ice Surface ◽

Aqueous Surface ◽

Organic Gases ◽

Global Emissions ◽

Urban Sites

Ammonium salts (NH4+) is the important component of PM2.5 and has a significant impact on air quality, climate, human health, and natural ecosystems. The contribution of NH4+ to PM2.5 is increasing at urban sites. Ammonia (NH3) with global emissions estimated at greater than 33 Tg(N) Yr-1 is the only precursor of particulate NH4+ in the atmosphere. Thus, it is important to understand the conversion kinetics from NH3 to NH4+ in the atmosphere. However, the uptake coefficient of NH3 (&#947;NH3) on aerosol particles are scarce at the present time. In this work, we reported the &#947;NH3 on ambient PM2.5 in Beijing and Shijiazhuang in China. The &#947;NH3 values on ambient PM2.5 are (1.13&#177;12.4)&#215;10-4 and (6.88&#177;40.7)&#215;10-4 in Shijiazhuang and Beijing, respectively. They are significantly lower than those on sulfuric acid droplet (0.1-1), aqueous surface (~5&#215;10-3-0.1) and acidified secondary organic aerosol (~10-3-~10-2), while are comparable with that on ice surface (5.3&#177;2.2 &#215;10-4) and on sulfuric acid in the presence of organic gases (2&#215;10-4-4&#215;10-3). An annual increase of &#947;NH3 in the statistic sense is observed and the possible reason related to the aerosol acidity has also been discussed.

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Secondary organic aerosol formation from biomass burning emissions

10.5194/acp-2019-326 ◽

2019 ◽

Cited By ~ 2

Author(s):

Christopher Y. Lim ◽

David H. Hagan ◽

Matthew M. Coggon ◽

Abigail R. Koss ◽

Kanako Sekimoto ◽

...

Keyword(s):

Biomass Burning ◽

Secondary Organic Aerosol ◽

Total Concentration ◽

Organic Aerosol ◽

Oh Radicals ◽

Aerosol Formation ◽

Atmospheric Aging ◽

Aerosol Mass ◽

Photochemical Aging ◽

Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

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Determining the Role of Acidity, Fate and Formation of IEPOX-Derived SOA in CMAQ

Atmosphere ◽

10.3390/atmos12060707 ◽

2021 ◽

Vol 12 (6) ◽

pp. 707

Author(s):

Petros Vasilakos ◽

Yongtao Hu ◽

Armistead Russell ◽

Athanasios Nenes

Keyword(s):

Significant Influence ◽

Organic Aerosol ◽

Liquid Water Content ◽

Anthropogenic Emissions ◽

So2 Emissions ◽

Aerosol Acidity ◽

A Value ◽

Future Emission ◽

The Impact

Formation of aerosol from biogenic hydrocarbons relies heavily on anthropogenic emissions since they control the availability of species such as sulfate and nitrate, and through them, aerosol acidity (pH). To elucidate the role that acidity and emissions play in regulating Secondary Organic Aerosol (SOA), we utilize the 2013 Southern Oxidant and Aerosol Study (SOAS) dataset to enhance the extensive mechanism of isoprene epoxydiol (IEPOX)-mediated SOA formation implemented in the Community Multiscale Air Quality (CMAQ) model (Pye et al., 2013), which was then used to investigate the impact of potential future emission controls on IEPOX OA. We found that the Henry’s law coefficient for IEPOX was the most impactful parameter that controls aqueous isoprene OA products, and a value of 1.9 × 107 M atm−1 provides the best agreement with measurements. Non-volatile cations (NVCs) were found in higher-than-expected quantities in CMAQ and exerted a significant influence on IEPOX OA by reducing its production by as much as 30% when present. Consistent with previous literature, a strong correlation of isoprene OA with sulfate, and little correlation with acidity or liquid water content, was found. Future reductions in SO2 emissions are found to not affect this correlation and generally act to increase the sensitivity of IEPOX OA to sulfate, even in extreme cases.

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Evaluation of Anthropogenic Secondary Organic Aerosol Tracers

10.5194/acp-2016-805 ◽

2016 ◽

Author(s):

Ibrahim M. Al-Naiema ◽

Elizabeth A. Stone

Keyword(s):

Phthalic Acid ◽

Secondary Organic Aerosol ◽

Dicarboxylic Acids ◽

Organic Aerosol ◽

Secondary Source ◽

Particle Phase ◽

Water Sensitivity ◽

Nitrobenzyl Alcohol ◽

Ambient Concentrations ◽

Highly Correlated

Abstract. Products of secondary organic aerosol (SOA) from aromatic volatile organic compounds (VOC) – 2,3-dihydroxy-4-oxopentanoic acid, dicarboxylic acids, nitromonoaromatics, and furandiones – were evaluated for their potential to serve as anthropogenic SOA tracers with respect to their 1) ambient concentrations and detectability in PM2.5 in Iowa City, IA, USA, 2) gas-particle partitioning behaviour, and 3) source specificity by way of correlations with primary and secondary source tracers and literature review. A widely used tracer for toluene-derived SOA, 2,3-dihydroxy-4-oxopentanoic acid was only detected in the particle phase (Fp = 1) at low, but consistently measureable ambient concentrations (averaging 0.3 ng m−3). Four aromatic dicarboxylic acids were detected at relatively higher concentrations (9.1–34.5 ng m−3), of which phthalic acid was the most abundant. Phthalic acid had a low particle-phase fraction (Fp = 0.26) likely due to quantitation interferences from phthalic anhydride, while 4-methylphthalic acid was predominantly in the particle phase (Fp = 0.82). Phthalic acid and 4-methyl phthalic acid were both highly correlated with 2,3-dihydroxy-4-oxopentanoic acid (rs = 0.73, p = 0.003; rs = 0.80, p < 0.001, respectively), suggesting that they were derived from aromatic VOC. Isophthalic and terephthalic acids, however, were detected only in the particle phase (Fp = 1) and correlations suggested association with primary emission sources. Nitromonoaromatics were dominated by particle-phase concentrations of 4-nitrocatechol (1.6 ng m−3) and 4-methyl-5-nitrocatechol (1.6 ng m−3) that were associated with biomass burning. Meanwhile, 4-hydroxy-3-nitrobenzyl alcohol was detected in a lower concentration (0.06 ng m−3) in the particle phase only (Fp = 1), and is known as a product of toluene photooxidation. Furandiones in the atmosphere have only been attributed to the photooxidation of aromatic hydrocarbons, however the substantial partitioning toward the gas phase (Fp ≤ 0.16) and their water sensitivity limit their application as tracers. The outcome of this study is the demonstration that 2,3-dihydroxy-4-oxopentanoic acid, phthalic acid, 4-methylphthalic acid, and 4-hydroxy-3-nitrobenzyl alcohol are good candidates for tracing SOA from aromatic VOC.

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Secondary Organic Aerosol Formation Enhanced by Organic Seeds of Similar Polarity at Atmospherically Relative Humidity

STEM Fellowship Journal ◽

10.17975/sfj-2015-009 ◽

2015 ◽

Vol 1 (2) ◽

pp. 6-10 ◽

Cited By ~ 3

Author(s):

Catherine A. Gordon ◽

Jianhuai Ye ◽

Arthur W.H. Chan

Keyword(s):

Climate Models ◽

Secondary Organic Aerosol ◽

Phase Particle ◽

Organic Aerosol ◽

Atmospheric Particulate Matter ◽

Oxidation Products ◽

Tetraethylene Glycol ◽

Aerosol Formation ◽

Volatile Oxidation Products ◽

Low Humidity

Secondary Organic Aerosol (SOA) forms in the atmosphere when semi-volatile oxidation products from biogenic and anthropogenic hydrocarbons condense onto atmospheric particulate matter. Climate models assume that oxidation products and preexisting organic aerosol form a well-mixed particle and enhance condensation, and, as a result, predict that future increases in anthropogenic primary organic aerosol (POA) will cause a significant increase in SOA. However, recent experiments performed at low humidity (<10%) demonstrate a single-phase particle does not always form, challenging the validity of model assumptions. In this work, we investigate the formation of SOA at atmospherically relevant humidities (55 - 65%) and examine this mixing assumption. We hypothesized that humidity leads to decreased viscosity and shorter mixing timescales, which is favorable for aerosol mixing. Here, α-pinene, a biogenic volatile organic compound is oxidized with ozone in a flow tube reactor in the presence of different organic aerosol seeds. Increased humidity did not enhance SOA formation with erythritol or squalane seed as hypothesized, implying that these compounds do not mix with α-pinene SOA in the range of humidities studied (55 – 65%). Yield enhancements were observed with tetraethylene glycol seed, demonstrating interaction between the SOA and seed. These observations suggest increased humidity does not promote mixing between the oxidation products and POA and highlight the need to fully understand the aerosol phase state in the atmosphere in order to better parameterize SOA formation and accurately predict future changes in air quality.

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Semi-continuous gas and inorganic aerosol measurements at a Finnish urban site: comparisons with filters, nitrogen in aerosol and gas phases, and aerosol acidity

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-4755-2012 ◽

2012 ◽

Vol 12 (2) ◽

pp. 4755-4796 ◽

Cited By ~ 3

Author(s):

U. Makkonen ◽

A. Virkkula ◽

J. Mäntykenttä ◽

H. Hakola ◽

P. Keronen ◽

...

Keyword(s):

Particle Number ◽

Road Traffic ◽

Large Fraction ◽

Inorganic Ions ◽

Urban Site ◽

Vehicle Exhaust ◽

Gas Phases ◽

Aerosol Acidity ◽

Inorganic Aerosol ◽

Online Monitor

Abstract. Concentrations of 5 gases (HCl, HNO3, HONO, NH3, SO2) and 8 major inorganic ions in particles (Cl−, NO3−, SO42−, NH4+, Na+, K+, Mg2+, Ca2+) were measured with an online monitor MARGA 2S in two size ranges, Dp < 2.5 μm and Dp < 10 μm, in Helsinki, Finland from November 2009 to May 2010. The results were compared with filter sampling, mass concentrations obtained from particle number size distributions, and a conventional SO2 monitor. The MARGA yielded lower concentrations than those analyzed from the filter samples for most ions. Linear regression yielded MARGA vs. filter slopes of 0.68, 0.89, 0.84, 0.52, 0.88, 0.17, 2.88, and 3.04 for Cl−, NO3−, SO42−, NH4+, Na+, K+, Mg2+, and Ca2+, respectively, and 0.90 for the MARGA vs. SO2 monitor. There were clear seasonal cycles in the concentrations of the nitrogen-containing gases: the median concentrations of HNO3, HONO, and NH3 were 0.09 ppb, 0.37 ppb, and 0.01 ppb in winter, respectively, and 0.15, 0.15, and 0.14 in spring, respectively. The gas-phase fraction of nitrogen decreased roughly with decreasing temperature so that in the coldest period from January to February the median contribution was 28% but in April to May 53%. There were also large fractionation variations that temperature alone cannot explain. HONO correlated well with NOx but a large fraction of the HONO-to-NOx ratios were larger than published ratios in a road traffic tunnel suggesting that a large amount of HONO had other sources than vehicle exhaust. Aerosol acidity was estimated by calculating ion equivalent ratios. The sources of acidic aerosols were studied with trajectory statistics that showed that continental aerosol is mainly neutralized and marine aerosol acidic.

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A biogenic secondary organic aerosol source of cirrus ice nucleating particles

Nature Communications ◽

10.1038/s41467-020-18424-6 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Martin J. Wolf ◽

Yue Zhang ◽

Maria A. Zawadowicz ◽

Megan Goodell ◽

Karl Froyd ◽

...

Keyword(s):

Laboratory Experiments ◽

Secondary Organic Aerosol ◽

Global Climate ◽

Compositional Analysis ◽

Field Measurements ◽

Organic Aerosol ◽

Cloud Formation ◽

Ambient Atmosphere ◽

Atmospheric Conditions ◽

Mass Fractions

Abstract Atmospheric ice nucleating particles (INPs) influence global climate by altering cloud formation, lifetime, and precipitation efficiency. The role of secondary organic aerosol (SOA) material as a source of INPs in the ambient atmosphere has not been well defined. Here, we demonstrate the potential for biogenic SOA to activate as depositional INPs in the upper troposphere by combining field measurements with laboratory experiments. Ambient INPs were measured in a remote mountaintop location at –46 °C and an ice supersaturation of 30% with concentrations ranging from 0.1 to 70 L–1. Concentrations of depositional INPs were positively correlated with the mass fractions and loadings of isoprene-derived secondary organic aerosols. Compositional analysis of ice residuals showed that ambient particles with isoprene-derived SOA material can act as depositional ice nuclei. Laboratory experiments further demonstrated the ability of isoprene-derived SOA to nucleate ice under a range of atmospheric conditions. We further show that ambient concentrations of isoprene-derived SOA can be competitive with other INP sources. This demonstrates that isoprene and potentially other biogenically-derived SOA materials could influence cirrus formation and properties.

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Evaluation of anthropogenic secondary organic aerosol tracers from aromatic hydrocarbons

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-2053-2017 ◽

2017 ◽

Vol 17 (3) ◽

pp. 2053-2065 ◽

Cited By ~ 33

Author(s):

Ibrahim M. Al-Naiema ◽

Elizabeth A. Stone

Keyword(s):

Aromatic Hydrocarbons ◽

Phthalic Acid ◽

Secondary Organic Aerosol ◽

Dicarboxylic Acids ◽

Organic Aerosol ◽

Secondary Source ◽

Particle Phase ◽

Water Sensitivity ◽

Nitrobenzyl Alcohol ◽

Ambient Concentrations

Abstract. Products of secondary organic aerosol (SOA) from aromatic volatile organic compounds (VOCs) – 2,3-dihydroxy-4-oxopentanoic acid, dicarboxylic acids, nitromonoaromatics, and furandiones – were evaluated for their potential to serve as anthropogenic SOA tracers with respect to their (1) ambient concentrations and detectability in PM2.5 in Iowa City, IA, USA; (2) gas–particle partitioning behaviour; and (3) source specificity by way of correlations with primary and secondary source tracers and literature review. A widely used tracer for toluene-derived SOA, 2,3-dihydroxy-4-oxopentanoic acid was only detected in the particle phase (Fp = 1) at low but consistently measurable ambient concentrations (averaging 0.3 ng m−3). Four aromatic dicarboxylic acids were detected at relatively higher concentrations (9.1–34.5 ng m−3), of which phthalic acid was the most abundant. Phthalic acid had a low particle-phase fraction (Fp =  0.26) likely due to quantitation interferences from phthalic anhydride, while 4-methylphthalic acid was predominantly in the particle phase (Fp = 0.82). Phthalic acid and 4-methylphthalic acid were both highly correlated with 2,3-dihydroxy-4-oxopentanoic acid (rs = 0.73, p = 0.003; rs = 0.80, p < 0.001, respectively), suggesting that they were derived from aromatic VOCs. Isophthalic and terephthalic acids, however, were detected only in the particle phase (Fp = 1), and correlations suggested association with primary emission sources. Nitromonoaromatics were dominated by particle-phase concentrations of 4-nitrocatechol (1.6 ng m−3) and 4-methyl-5-nitrocatechol (1.6 ng m−3) that were associated with biomass burning. Meanwhile, 4-hydroxy-3-nitrobenzyl alcohol was detected in a lower concentration (0.06 ng m−3) in the particle phase only (Fp = 1) and is known as a product of toluene photooxidation. Furandiones in the atmosphere have only been attributed to the photooxidation of aromatic hydrocarbons; however the substantial partitioning toward the gas phase (Fp  ≤  0.16) and their water sensitivity limit their application as tracers. The outcome of this study is the demonstration that 2,3-dihydroxy-4-oxopentanoic acid, phthalic acid, 4-methylphthalic acid, and 4-hydroxy-3-nitrobenzyl alcohol are good candidates for tracing SOA from aromatic VOCs.

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