scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (18) ◽  
pp. 8711-8726 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. Phthalic anhydride uptake (and hydrolysis) was tested and found to represent a moderate filter artifact in filter measurements with and without in-line denuders. This study provided the opportunity to examine differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.0199 (recommended for ambient samples) and 0.0206 were determined in the presence and absence of nitrogen oxides, respectively, based on phthalic acid standards. The mass fractions determined from the laboratory data were applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other methylnaphthalenes. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the 2-ring precursor PAHs (as naphthalene) were found to range from below the detection limit to 20 ngC m−3 which with the laboratory mass fraction data suggests an upper limit of approximately 1 μg m−3 for SOA due to 2-ring PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection media.

scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (5) ◽  
pp. 12163-12201 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Gas Phase ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. In addition, the hydrolysis of phthalic anhydride was tested and found to represent a moderate filter artifact in side-by-side filter measurements with and without in-line denuders. This study also provided the opportunity to examine numeric differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.023 and 0.019 were determined in the presence and absence of nitrogen oxides, respectively, based on the phthalic acid standards. The mass fractions determined from the laboratory data were then applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other PAHs tested. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the gas-phase PAHs (as naphthalene) were found to range from below the detection limit to 20 ng C m−3 which together with the laboratory mass fraction data suggests an upper limit of 1 μg m−3 for SOA due to PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential gas-phase hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection medium.

scholarly journals α-pinene secondary organic aerosol at low temperature: Chemical composition and implications for particle viscosity

2017 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Aki Pajunoja ◽  
Xiaoli Shen ◽  
Karl-Heinz Naumann ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Physicochemical Properties ◽  
Mass Fraction ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Temperature ◽  
Mass Fractions

Abstract. Chemical composition and viscosity of secondary organic aerosol (SOA) from α-pinene (C10H16) ozonolysis were investigated for low temperature conditions (223 K). Two types of experiments were performed using two simulation chambers at the Karlsruhe Institute of Technology, the Aerosol Preparation and Characterization chamber (APC), and the Aerosol Interaction and Dynamics in the Atmosphere chamber (AIDA). Experiment type 1 simulated SOA formation at upper tropospheric conditions: SOA was generated in the AIDA chamber directly at 223 K, 61 % relative humidity (RH) (experiment termed cold humid, CH), or for comparison at 6 % RH (experiment termed cold dry, CD) conditions. Experiment type 2 simulated SOA uplifting: SOA was formed in the APC chamber at room temperature (296 K), <1 % RH (experiment termed warm dry, WD) or 21 % RH (experiment termed warm humid, WH) conditions, and then partially transferred to the AIDA chamber kept at 223 K, and 61 % RH (WDtoCH) or 30 % RH (WHtoCH), respectively. Precursor concentrations varied between 0.7 and 2.2 ppm α-pinene, and 2.3 and 1.8 ppm ozone for type 1 and type 2 experiments, respectively. Among other instrumentation, a chemical ionization mass spectrometer (CIMS) with filter inlet for gases and aerosols (FIGAERO), deploying I- as reagent ion, was used for SOA chemical composition analysis. For type 1 experiments with lower α-pinene concentration and cold SOA formation temperature (223 K), smaller particles of 100–300 nm vacuum aerodynamic diameter (dva) and higher mass fractions (>40 %) of adducts (molecules with more than 10 carbon atoms) of α-pinene oxidation products were observed. For type 2 experiments with higher α-pinene concentration and warm SOA formation temperature (296 K), larger particles (~500 nm dva) with smaller mass fractions of adducts (<35 %) were produced. We also observed differences (up to 20 ºC) in maximum desorption temperature (Tmax) of individual compounds desorbing from the particles deposited on the FIGAERO Teflon filter for different experiments, indicating that Tmax is not purely a function of a compound's vapor pressure or volatility, but is also influenced by diffusion limitations within the particles (particle viscosity), interactions between particles deposited on the filter (particle matrix), and/or particle mass on the filter. Highest Tmax were observed for SOA under dry conditions and with higher adduct mass fraction; lowest Tmax for SOA under humid conditions and with lowest adduct mass fraction. The observations indicate that particle viscosity may be influenced by intra- and inter-molecular hydrogen bonding between oligomers, and particle water uptake, even under such low temperature conditions. Our results suggest that particle physicochemical properties such as viscosity and oligomer content mutually influence each other, and that variation in Tmax of particle desorptions may provide implications for particle viscosity and particle matrix effects. The differences in particle physicochemical properties observed between our different experiments demonstrate the importance of taking experimental conditions into consideration when interpreting data from laboratory studies or using them as input in climate models.

scholarly journals Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction

2007 ◽  
Vol 7 (1) ◽  
pp. 1941-1967 ◽  
Author(s):  
R. K. Pathak ◽  
A. A. Presto ◽  
T. E. Lane ◽  
C. O. Stanier ◽  
N. M. Donahue ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Organic Aerosol ◽  
Basis Set ◽  
Smog Chamber ◽  
Equilibrium Partitioning ◽  
Research Teams ◽  
Aerosol Mass ◽  
Wide Range ◽  
Mass Fractions ◽  
Dry Conditions

Abstract. Existing parameterizations tend to underpredict the α-pinene aerosol mass fraction (AMF) by a factor of 2–5 at low organic aerosol concentrations (<5 μg m−3). A wide range of smog chamber results obtained at various conditions (low/high NOx, presence/absence of UV radiation, dry/humid conditions, and temperatures ranging from 15–40°C) collected by various research teams during the last decade are used to derive new parameterizations of the SOA formation from α-pinene ozonolysis. Parameterizations are developed by fitting experimental data to a basis set of saturation concentrations (from 10−2 to 104 μg m−3) using an absorptive equilibrium partitioning model. Separate parameterizations for α-pinene SOA mass fractions are developed for: 1) Low NOx, dark, and dry conditions, 2) Low NOx, UV, and dry conditions, 3) Low NOx, dark, and high RH conditions, 4) High NOx, dark, and dry conditions, 5) High NOx, UV, and dry conditions. According to the proposed parameterizations the α-pinene SOA mass fractions in an atmosphere with 5 μg m−3 of organic aerosol range from 0.032 to 0.1 for reacted α-pinene concentrations in the 1 ppt to 5 ppb range.

Parameterization of secondary organic aerosol mass fractions from smog chamber data

2008 ◽  
Vol 42 (10) ◽  
pp. 2276-2299 ◽  
Author(s):  
Charles O. Stanier ◽  
Neil Donahue ◽  
Spyros N. Pandis
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Mass ◽  
Mass Fractions

scholarly journals Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction

2007 ◽  
Vol 7 (14) ◽  
pp. 3811-3821 ◽  
Author(s):  
R. K. Pathak ◽  
A. A. Presto ◽  
T. E. Lane ◽  
C. O. Stanier ◽  
N. M. Donahue ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Organic Aerosol ◽  
Basis Set ◽  
Smog Chamber ◽  
Equilibrium Partitioning ◽  
Research Teams ◽  
Aerosol Mass ◽  
Wide Range ◽  
Mass Fractions ◽  
Dry Conditions

Abstract. Existing parameterizations tend to underpredict the α-pinene aerosol mass fraction (AMF) or yield by a factor of 2–5 at low organic aerosol concentrations (<5 µg m−3). A wide range of smog chamber results obtained at various conditions (low/high NOx, presence/absence of UV radiation, dry/humid conditions, and temperatures ranging from 15–40°C) collected by various research teams during the last decade are used to derive new parameterizations of the SOA formation from α-pinene ozonolysis. Parameterizations are developed by fitting experimental data to a basis set of saturation concentrations (from 10−2 to 104 µg m−3) using an absorptive equilibrium partitioning model. Separate parameterizations for α-pinene SOA mass fractions are developed for: 1) Low NOx, dark, and dry conditions, 2) Low NOx, UV, and dry conditions, 3) Low NOx, dark, and high RH conditions, 4) High NOx, dark, and dry conditions, 5) High NOx, UV, and dry conditions. According to the proposed parameterizations the α-pinene SOA mass fractions in an atmosphere with 5 µg m−3 of organic aerosol range from 0.032 to 0.1 for reacted α-pinene concentrations in the 1 ppt to 5 ppb range.

Secondary organic aerosol formation from ethyne in the presence of NaCl in a smog chamber

2016 ◽  
Vol 13 (4) ◽  
pp. 699 ◽  
Author(s):  
Shuangshuang Ge ◽  
Yongfu Xu ◽  
Long Jia
Keyword(s):  
Sodium Chloride ◽  
Relative Humidity ◽  
Nitrogen Oxides ◽  
Secondary Organic Aerosol ◽  
Geometric Mean ◽  
Organic Aerosol ◽  
Photochemical Oxidation ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Organic Particles

Environmental context Ethyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles. Abstract The heterogeneous photochemical oxidation of ethyne was investigated under different relative humidity (RH) conditions in the presence of nitrogen oxides and sodium chloride in a self-made indoor smog chamber. The purpose was to study the influence of RH on the formation of secondary organic aerosol (SOA) from C2H2. Through the experiments, we found that SOA was rarely formed at <22% RH in the presence of NaCl seed particles, and that SOA began to be formed at ≥29% RH in the presence of NaCl, which shows the importance of RH in the formation of SOA. The yield of SOA (YSOA) from C2H2 was 0.2% at 51% RH, and increased by a factor of 17.5 as RH reached 83%. The SOA yield increased with increasing RH. The geometric mean diameter of the particles increased by a factor of 1.17, 1.22, 1.28 and 1.51 at a RH of 51, 63, 74 and 83% respectively at the end of the experiment, indicating that the growth of the particle size also increased with increasing RH. Analysis of the SOA with Fourier-transform infrared (FTIR) spectrometry indicated that the particles generated from C2H2 contained the functional groups –OH, C=O, C–O–C and C–C–OH, for whose absorption peaks increase with increasing RH.

scholarly journals <i>α</i>-Pinene secondary organic aerosol at low temperature: chemical composition and implications for particle viscosity

2018 ◽  
Vol 18 (4) ◽  
pp. 2883-2898 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Aki Pajunoja ◽  
Xiaoli Shen ◽  
Karl-Heinz Naumann ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Physicochemical Properties ◽  
Mass Fraction ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Temperature ◽  
Mass Fractions

Abstract. Chemical composition, size distributions, and degree of oligomerization of secondary organic aerosol (SOA) from α-pinene (C10H16) ozonolysis were investigated for low-temperature conditions (223 K). Two types of experiments were performed using two simulation chambers at the Karlsruhe Institute of Technology: the Aerosol Preparation and Characterization (APC) chamber, and the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber. Experiment type 1 simulated SOA formation at upper tropospheric conditions: SOA was generated in the AIDA chamber directly at 223 K at 61 % relative humidity (RH; experiment termed “cold humid”, CH) and for comparison at 6 % RH (experiment termed “cold dry”, CD) conditions. Experiment type 2 simulated SOA uplifting: SOA was formed in the APC chamber at room temperature (296 K) and < 1 % RH (experiment termed “warm dry”, WD) or 21 % RH (experiment termed “warm humid”, WH) conditions, and then partially transferred to the AIDA chamber kept at 223 K, and 61 % RH (WDtoCH) or 30 % RH (WHtoCH), respectively. Precursor concentrations varied between 0.7 and 2.2 ppm α-pinene, and between 2.3 and 1.8 ppm ozone for type 1 and type 2 experiments, respectively. Among other instrumentation, a chemical ionization mass spectrometer (CIMS) coupled to a filter inlet for gases and aerosols (FIGAERO), deploying I− as reagent ion, was used for SOA chemical composition analysis. For type 1 experiments with lower α-pinene concentrations and cold SOA formation temperature (223 K), smaller particles of 100–300 nm vacuum aerodynamic diameter (dva) and higher mass fractions (> 40 %) of adducts (molecules with more than 10 carbon atoms) of α-pinene oxidation products were observed. For type 2 experiments with higher α-pinene concentrations and warm SOA formation temperature (296 K), larger particles (∼ 500 nm dva) with smaller mass fractions of adducts (< 35 %) were produced. We also observed differences (up to 20 ∘C) in maximum desorption temperature (Tmax) of individual compounds desorbing from the particles deposited on the FIGAERO Teflon filter for different experiments, indicating that Tmax is not purely a function of a compound's vapor pressure or volatility, but is also influenced by diffusion limitations within the particles (particle viscosity), interactions between particles deposited on the filter (particle matrix), and/or particle mass on the filter. Highest Tmax were observed for SOA under dry conditions and with higher adduct mass fraction; lowest Tmax were observed for SOA under humid conditions and with lower adduct mass fraction. The observations indicate that particle viscosity may be influenced by intra- and inter-molecular hydrogen bonding between oligomers, and particle water uptake, even under such low-temperature conditions. Our results suggest that particle physicochemical properties such as viscosity and oligomer content mutually influence each other, and that variation in Tmax of particle desorptions may have implications for particle viscosity and particle matrix effects. The differences in particle physicochemical properties observed between our different experiments demonstrate the importance of taking experimental conditions into consideration when interpreting data from laboratory studies or using them as input in climate models.

scholarly journals Evaluation of Anthropogenic Secondary Organic Aerosol Tracers

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.

scholarly journals Impact of aftertreatment devices on primary emissions and secondary organic aerosol formation potential from in-use diesel vehicles: results from smog chamber experiments

2010 ◽  
Vol 10 (6) ◽  
pp. 16055-16109 ◽  
Author(s):  
R. Chirico ◽  
P. F. DeCarlo ◽  
M. F. Heringa ◽  
T. Tritscher ◽  
R. Richter ◽  
...  
Keyword(s):  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Aftertreatment ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Diesel Particulate ◽  
Diesel Vehicles

Abstract. Diesel particulate matter (DPM) is a significant source of aerosol in urban areas and has been linked to adverse health effects. Although newer European directives have introduced increasingly stringent standards for primary PM emissions, gaseous organics emitted from diesel cars can still lead to large amounts of secondary organic aerosol (SOA) in the atmosphere. Here we present results from smog chamber investigations characterizing the primary organic aerosol (POA) and the corresponding SOA formation at atmospherically relevant concentrations for three in-use diesel vehicles with different exhaust aftertreatment systems. One vehicle lacked exhaust aftertreatment devices, one vehicle was equipped with a diesel oxidation catalyst (DOC) and the final vehicle used both a DOC and diesel particulate filter (DPF). The experiments presented here were obtained from the vehicles at conditions representative of idle mode, and for one car in addition at a speed of 60 km/h. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was used to measure the organic aerosol (OA) concentration and to obtain information on the chemical composition. For the conditions explored in this paper, primary aerosols from vehicles without a particulate filter consisted mainly of black carbon (BC) with a low fraction of organic matter (OM, OM/BC<0.5), while the subsequent aging by photooxidation resulted in a consistent production of SOA only for the vehicles without a DOC and with a deactivated DOC. After 5 h of aging ~80% of the total organic aerosol was on average secondary and the estimated "emission factor" for SOA was 0.23–0.56 g/kg fuel burned. In presence of both a DOC and a DPF, primary particles with a mobility diameter above 5 nm were 300±19 cm−3, and only 0.01 g SOA per kg fuel burned was produced within 5 h after lights on. The mass spectra indicate that POA was mostly a non-oxidized OA with an oxygen to carbon atomic ratio (O/C) ranging from 0.097 to 0.190. Five hours of oxidation led to a more oxidized OA with an O/C range of 0.208 to 0.369.

scholarly journals A biogenic secondary organic aerosol source of cirrus ice nucleating particles

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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