Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

Abstract. In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. For our analysis, average thermodynamic properties (i.e., molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. We have found that, the molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol−1 and 780±231 g mol−1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

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Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-799-2008 ◽

2008 ◽

Vol 8 (4) ◽

pp. 799-812 ◽

Cited By ~ 114

Author(s):

A. Asa-Awuku ◽

A. P. Sullivan ◽

C. J. Hennigan ◽

R. J. Weber ◽

A. Nenes

Keyword(s):

Surface Tension ◽

Molar Volume ◽

Biomass Burning ◽

Solid Phase ◽

Relative Proportion ◽

Water Soluble ◽

Original Sample ◽

Biomass Burning Aerosol ◽

Hydrophobic Fraction ◽

Ccn Activity

Abstract. In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. From our analysis, average thermodynamic properties (i.e, molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. The molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol−1 and 780±231 g mol−1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

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Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: implications for cloud condensation nucleus activity

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-6771-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 6771-6819

Author(s):

J. H. Slade ◽

R. Thalman ◽

J. Wang ◽

D. A. Knopf

Keyword(s):

Biomass Burning ◽

Wet Deposition ◽

Water Solubility ◽

Inorganic Compounds ◽

Organic Aerosol ◽

Water Soluble ◽

Oh Radicals ◽

Chemical Aging ◽

Biomass Burning Aerosol ◽

Ccn Activity

Abstract. Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O3 can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient amount of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the water-soluble fraction and not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide-range of solubilities.

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Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-10183-2015 ◽

2015 ◽

Vol 15 (17) ◽

pp. 10183-10201 ◽

Cited By ~ 16

Author(s):

J. H. Slade ◽

R. Thalman ◽

J. Wang ◽

D. A. Knopf

Keyword(s):

Biomass Burning ◽

Wet Deposition ◽

Water Solubility ◽

Inorganic Compounds ◽

Organic Aerosol ◽

Water Soluble ◽

Oh Radicals ◽

Chemical Aging ◽

Biomass Burning Aerosol ◽

Ccn Activity

Abstract. Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient number of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the water-soluble fraction and is not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide range of solubilities.

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Water-soluble SOA from Alkene ozonolysis: composition and droplet activation kinetics inferences from analysis of CCN activity

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-1585-2010 ◽

2010 ◽

Vol 10 (4) ◽

pp. 1585-1597 ◽

Cited By ~ 74

Author(s):

A. Asa-Awuku ◽

A. Nenes ◽

S. Gao ◽

R. C. Flagan ◽

J. H. Seinfeld

Keyword(s):

Surface Tension ◽

Molar Volume ◽

Volume Fraction ◽

Pure Water ◽

Water Soluble ◽

Cloud Formation ◽

Droplet Growth ◽

Activation Kinetics ◽

Kohler Theory ◽

Ccn Activity

Abstract. Cloud formation characteristics of the water-soluble organic fraction (WSOC) of secondary organic aerosol (SOA) formed from the ozonolysis of alkene hydrocarbons (terpinolene, 1-methlycycloheptene and cycloheptene) are studied. Based on size-resolved measurements of CCN activity (of the pure and salted WSOC samples) we estimate the average molar volume and surface tension depression associated with the WSOC using Köhler Theory Analysis (KTA). Consistent with known speciation, the results suggest that the WSOC are composed of low molecular weight species, with an effective molar mass below 200 g mol−1. The water-soluble carbon is also surface-active, depressing surface tension 10–15% from that of pure water (at CCN-relevant concentrations). The inherent hygroscopicity parameter, κ, of the WSOC ranges between 0.17 and 0.25; if surface tension depression and molar volume effects are considered in κ, a remarkably constant "apparent" hygroscopicity ~0.3 emerges for all samples considered. This implies that the volume fraction of soluble material in the parent aerosol is the key composition parameter required for prediction of the SOA hygroscopicity, as shifts in molar volume across samples are compensated by changes in surface tension. Finally, using "threshold droplet growth analysis", the water-soluble organics in all samples considered do not affect CCN activation kinetics.

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Hygroscopic properties of Amazonian biomass burning and European background HULIS and investigation of their effects on surface tension with two models linking H-TDMA to CCNC data

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-5625-2010 ◽

2010 ◽

Vol 10 (12) ◽

pp. 5625-5639 ◽

Cited By ~ 38

Author(s):

E. O. Fors ◽

J. Rissler ◽

A. Massling ◽

B. Svenningsson ◽

M. O. Andreae ◽

...

Keyword(s):

Surface Tension ◽

Biomass Burning ◽

Organic Material ◽

Inorganic Compounds ◽

Pure Water ◽

Condensation Nucleus ◽

Water Soluble ◽

Cloud Condensation Nucleus ◽

Rural Site ◽

Hygroscopic Properties

Abstract. HUmic-LIke Substances (HULIS) have been identified as major contributors to the organic carbon in atmospheric aerosol. The term "HULIS" is used to describe the organic material found in aerosol particles that resembles the humic organic material in rivers and sea water and in soils. In this study, two sets of filter samples from atmospheric aerosols were collected at different sites. One set of samples was collected at the K-puszta rural site in Hungary, about 80 km SE of Budapest, and a second was collected at a site in Rondônia, Amazonia, Brazil, during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) biomass burning season experiment. HULIS were extracted from the samples and their hygroscopic properties were studied using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) at relative humidity (RH) <100%, and a cloud condensation nucleus counter (CCNC) at RH >100%. The H-TDMA measurements were carried out at a dry diameter of 100 nm and for RH ranging from 30 to 98%. At 90% RH the HULIS samples showed diameter growth factors between 1.04 and 1.07, reaching values of 1.4 at 98% RH. The cloud nucleating properties of the two sets of aerosol samples were analysed using two types of thermal static cloud condensation nucleus counters. Two different parameterization models were applied to investigate the potential effect of HULIS surface activity, both yielding similar results. For the K-puszta winter HULIS sample, the surface tension at the point of activation was estimated to be lowered by between 34% (47.7 mN/m) and 31% (50.3 mN/m) for dry sizes between 50 and 120 nm in comparison to pure water. A moderate lowering was also observed for the entire water soluble aerosol sample, including both organic and inorganic compounds, where the surface tension was decreased by between 2% (71.2 mN/m) and 13% (63.3 mN/m).

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Rebuttal to Correspondence on “Changes in Droplet Surface Tension Affect the Observed Hygroscopicity of Photochemically Aged Biomass Burning Aerosol”

Environmental Science & Technology ◽

10.1021/es405374r ◽

2014 ◽

Vol 48 (3) ◽

pp. 2084-2085 ◽

Cited By ~ 2

Author(s):

Michael R. Giordano ◽

Akua Asa-Awuku

Keyword(s):

Surface Tension ◽

Biomass Burning ◽

Droplet Surface ◽

Biomass Burning Aerosol

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Biomass burning contribution to Beijing aerosol

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-8387-2013 ◽

2013 ◽

Vol 13 (3) ◽

pp. 8387-8434 ◽

Cited By ~ 5

Author(s):

Y. Cheng ◽

G. Engling ◽

K. B. He ◽

F. K. Duan ◽

Y. L. Ma ◽

...

Keyword(s):

Biomass Burning ◽

Elemental Carbon ◽

Organic Aerosol ◽

Water Soluble ◽

Winter Period ◽

Summer Period ◽

Pmf Model ◽

Different Types ◽

Biomass Burning Aerosol ◽

Typical Summer

Abstract. Biomass burning, the largest global source of elemental carbon (EC) and primary organic carbon (OC), is strongly associated with many subjects of great scientific concern, such as secondary organic aerosol and brown carbon which exert important effects on the environment and on climate in particular. This study investigated the relationships between levoglucosan and other biomass burning tracers (i.e. water soluble potassium and mannosan) based on both ambient samples collected in Beijing and source samples. Compared with North America and Europe, Beijing was characterized by high ambient levoglucosan concentrations and low winter to summer ratios of levoglucosan, indicating significant impact of biomass burning activities throughout the year in Beijing. Comparison of levoglucosan and water soluble potassium (K+) levels suggested that it was acceptable to use K+ as a biomass burning tracer during summer in Beijing, while the contribution of fireworks to K+ could be significant during winter. Moreover, the levoglucosan to K+ ratio was found to be lower during the typical summer period (0.21±0.16) compared with the typical winter period (0.51±0.15). On the other hand, levoglucosan correlated strongly with mannosan (R2=0.97) throughout the winter and the levoglucosan to mannosan ratio averaged 9.49±1.63, whereas levoglucosan and mannosan exhibited relatively weak correlation (R2=0.73) during the typical summer period when the levoglucosan to mannosan ratio averaged 12.65±3.38. Results from PMF model analysis showed that about 50% of the OC and EC in Beijing were associated with biomass burning processes. In addition, a new source-identification method was developed based on the comparison of the levoglucosan to K+ ratio and the levoglucosan to mannosan ratio among different types of biomass. Using this method, the major source of biomass burning aerosol in Beijing was suggested to be the combustion of crop residuals, while the contribution from softwood burning was also non-negligible, especially in winter.

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Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds

10.5194/acp-2016-860 ◽

2016 ◽

Author(s):

Wing Y. Tuet ◽

Yunle Chen ◽

Lu Xu ◽

Shierly Fok ◽

Dong Gao ◽

...

Keyword(s):

Health Effects ◽

Biomass Burning ◽

Organic Aerosol ◽

Water Soluble ◽

Hydrocarbon Emissions ◽

Reaction Conditions ◽

Oxidative Potential ◽

Incomplete Combustion ◽

Volatile Organic ◽

Biomass Burning Aerosol

Abstract. Particulate matter (PM), of which a significant fraction is comprised of secondary organic aerosols (SOA), has received considerable attention due to their health implications. In this study, the water-soluble oxidative potential (OPWS) of SOA generated from the photooxidation of biogenic and anthropogenic hydrocarbon precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different reaction conditions (RO2 + HO2/RO2 + NO dominant, dry/humid) was characterized using dithiothreitol (DTT) consumption. The measured intrinsic OPWS-DTT ranged from 9–205 pmol min−1 µg−1 and were highly dependent on the specific hydrocarbon precursor, with naphthalene and isoprene SOA generating the highest and lowest OPWS-DTT, respectively. Humidity and RO2 fate affected OPWS-DTT in a hydrocarbon-specific manner, with naphthalene SOA exhibiting the most pronounced effects, likely due to the formation of nitroaromatics. Together, these results suggest that precursor identity may be more influential than reaction condition in determining SOA health effects, demonstrating the importance of sources, such as incomplete combustion, to aerosol toxicity. In the context of other PM sources, all SOA systems with the exception of naphthalene SOA were less DTT active than ambient sources related to incomplete combustion, including diesel and gasoline combustion as well as biomass burning. Finally, naphthalene SOA was as DTT active as biomass burning aerosol, which was found to be the most DTT active OA source in a previous ambient study. These results highlight a need to consider SOA contributions (particularly from anthropogenic hydrocarbons) to health effects in the context of hydrocarbon emissions, SOA yields, and other PM sources.

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Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-839-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 839-853 ◽

Cited By ~ 69

Author(s):

Wing Y. Tuet ◽

Yunle Chen ◽

Lu Xu ◽

Shierly Fok ◽

Dong Gao ◽

...

Keyword(s):

Biomass Burning ◽

Organic Aerosol ◽

Water Soluble ◽

Hydrocarbon Emissions ◽

Reaction Conditions ◽

Oxidative Potential ◽

Incomplete Combustion ◽

Volatile Organic ◽

Specific Manner ◽

Biomass Burning Aerosol

Abstract. Particulate matter (PM), of which a significant fraction is comprised of secondary organic aerosols (SOA), has received considerable attention due to its health implications. In this study, the water-soluble oxidative potential (OPWS) of SOA generated from the photooxidation of biogenic and anthropogenic hydrocarbon precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different reaction conditions (RO2+ HO2 vs. RO2+ NO dominant, dry vs. humid) was characterized using dithiothreitol (DTT) consumption. The measured intrinsic OPWS-DTT values ranged from 9 to 205 pmol min−1 µg−1 and were highly dependent on the specific hydrocarbon precursor, with naphthalene and isoprene SOA generating the highest and lowest OPWS-DTT values, respectively. Humidity and RO2 fate affected OPWS-DTT in a hydrocarbon-specific manner, with naphthalene SOA exhibiting the most pronounced effects, likely due to the formation of nitroaromatics. Together, these results suggest that precursor identity may be more influential than reaction condition in determining SOA oxidative potential, demonstrating the importance of sources, such as incomplete combustion, to aerosol toxicity. In the context of other PM sources, all SOA systems, with the exception of naphthalene SOA, were less DTT active than ambient sources related to incomplete combustion, including diesel and gasoline combustion as well as biomass burning. Finally, naphthalene SOA was as DTT active as biomass burning aerosol, which was found to be the most DTT-active OA source in a previous ambient study. These results highlight a need to consider SOA contributions (particularly from anthropogenic hydrocarbons) to health effects in the context of hydrocarbon emissions, SOA yields, and other PM sources.

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