scholarly journals Are sesquiterpenes a good source of secondary organic cloud condensation nuclei (CCN)? Revisiting β-caryophyllene CCN

2012 ◽  
Vol 12 (18) ◽  
pp. 8377-8388 ◽  
Author(s):  
X. Tang ◽  
D. R. Cocker ◽  
A. Asa-Awuku
Keyword(s):  
Molecular Weight ◽  
Oxidation State ◽  
Cloud Condensation Nuclei ◽  
Reaction Chamber ◽  
Lower Molecular Weight ◽  
Chemical Information ◽  
Condensation Nuclei ◽  
Low Concentrations ◽  
Predictive Understanding ◽  
Ccn Activity

Abstract. Secondary organic aerosol (SOA) was formed in an environmental reaction chamber from the ozonolysis of β-caryophyllene (β-C) at low concentrations (5 ppb or 20 ppb). Experimental parameters were varied to characterize the effects of hydroxyl radicals, light and the presence of lower molecular weight terpene precursor (isoprene) for β-C SOA formation and cloud condensation nuclei (CCN) characteristics. Changes in β-C SOA chemicophysical properties (e.g., density, volatility, oxidation state) were explored with online techniques to improve our predictive understanding of β-C CCN activity. In the absence of OH scavenger, light intensity had negligible impacts on SOA oxidation state and CCN activity. In contrast, when OH reaction was effectively suppressed (> 11 ppm scavenger), SOA showed a much lower CCN activity and slightly less oxygenated state consistent with previously reported values. Though there is significant oxidized material present (O / C > 0.25), no linear correlation existed between the mass ratio ion fragment 44 in the bulk organic mass (f44) and O / C for the β-C-O3 system. No direct correlations were observed with other aerosol bulk ion fragment fraction (fx) and κ as well. A mixture of β-C and lower molecular weight terpenes (isoprene) consumed more ozone and formed SOA with distinct characteristics dependent on isoprene amounts. The addition of isoprene also improved the CCN predictive capabilities with bulk aerosol chemical information. The β-C SOA CCN activity reported here is much higher than previous studies (κ < 0.1) that use higher precursor concentration in smaller environmental chambers; similar results were only achieved with significant use of OH scavenger. Results show that aerosol formed from a mixture of low and high molecular weight terpene ozonolysis can be hygroscopic and can contribute to the global biogenic SOA CCN budget.

scholarly journals Are sesquiterpenes a good source of secondary organic cloud condensation nuclei (CCN)? Revisiting <i>β</i>-caryophyllene CCN

2012 ◽  
Vol 12 (4) ◽  
pp. 8547-8577 ◽  
Author(s):  
X. Tang ◽  
D. R. Cocker III ◽  
A. Asa-Awuku
Keyword(s):  
Molecular Weight ◽  
Oxidation State ◽  
Cloud Condensation Nuclei ◽  
Reaction Chamber ◽  
Lower Molecular Weight ◽  
Chemical Information ◽  
Ambient Conditions ◽  
Condensation Nuclei ◽  
Predictive Understanding ◽  
Ccn Activity

Abstract. Secondary organic aerosol (SOA) was formed in an environmental reaction chamber from the ozonolysis of β-caryophyllene (β-C) at very low concentrations (5 ppb or 20 ppb) near ambient conditions. Experimental parameters were varied to characterize the effects of hydroxyl radicals, light and the presence of lower molecular weight terpene precursor (isoprene) for β-C SOA formation and Cloud Condensation Nuclei (CCN) characteristics. Changes in β-C SOA chemicophysical properties (e.g. density, volatility, oxidation state) were explored with online techniques to improve our predictive understanding of β-C CCN activity. In the absence of OH scavenger, light intensity had negligible impacts on SOA oxidation state and CCN activity. In contrast, when OH reaction was effectively suppressed (>11ppm scavenger), SOA showed a much lower CCN activity and slightly less oxygenated state consistent with previously reported values. Though there is significant oxidized material present (O/C>0.25), no linear correlation existed between the mass ratio ion fragment 44 in the bulk organic mass (f44) and O/C for the β-C-O3 system. No direct correlations were observed with other aerosol bulk ion fragment fraction (fx) and κ as well. A mixture of β-C and lower molecular weight terpenes (isoprene) consumed more ozone and formed SOA with distinct characteristics dependent on isoprene amounts. The addition of isoprene also improved the CCN predictive capabilities with bulk aerosol chemical information. The β-C SOA CCN activity reported here is much higher than previous studies (κ>0.1) that use higher precursor concentration in smaller environmental chambers; similar results were only achieved with significant use of OH scavenger. Results show that aerosol formed from a mixture of low and high molecular weight terpene ozonolysis can be hygroscopic and can contribute to the global biogenic SOA CCN budget.

scholarly journals Impact of aerosol composition on cloud condensation nuclei activity

2012 ◽  
Vol 12 (8) ◽  
pp. 3783-3790 ◽  
Author(s):  
Q. Zhang ◽  
J. Meng ◽  
J. Quan ◽  
Y. Gao ◽  
D. Zhao ◽  
...  
Keyword(s):  
Size Distribution ◽  
Field Experiments ◽  
Cloud Condensation Nuclei ◽  
Diffusion Chamber ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Rate Of Increase ◽  
The Impact ◽  
Ccn Activity

Abstract. The impact of aerosol composition on cloud condensation nuclei (CCN) activity were analyzed in this study based on field experiments carried out at downtown Tianjin, China in September 2010. In the experiments, the CCN measurements were performed at supersaturation (SS) of 0.1%, 0.2% and 0.4% using a thermal-gradient diffusion chamber (DMT CCNC), whereas the aerosol size distribution and composition were simultaneously measured with a TSI SMPS and an Aerodyne Aerosol Mass Spectrometer (AMS), respectively. The results show that the influence of aerosol composition on CCN activity is notable under low SS (0.1%), and their influence decreased with increasing SS. For example, under SS of 0.1%, the CCN activity increases from 4.5±2.6% to 12.8±6.1% when organics fraction decrease from 30–40% to 10–20%. The rate of increase reached up to 184%. While under SS of 0.4%, the CCN activity increases only from 35.7±19.0% to 46.5±12.3% correspondingly. The calculated NCCN based on the size-resolved activation ratio and aerosol number size distribution correlated well with observed NCCN at high SS (0.4%), but this consistence decreased with the falling of SS. The slopes of linear fitted lines between calculated and observed NCCN are 0.708, 0.947, and 0.995 at SS of 0.1%, 0.2% and 0.4% respectively. Moreover, the stand deviation (SD) of calculated NCCN increased with the decreasing of SS. A case study of CCN closure analyses indicated that the calculated error of NCCN could reach up to 34% at SS of 0.1% if aerosol composition were not included, and the calculated error decreased with the raising of SS. It is decreased to 9% at SS of 0.2%, and further decreased to 4% at SS of 0.4%.

scholarly journals Cloud condensation nuclei activity of CaCO<sub>3</sub> particles with oleic acid and malonic acid coatings

2018 ◽  
Vol 18 (10) ◽  
pp. 7345-7359 ◽  
Author(s):  
Mingjin Wang ◽  
Tong Zhu ◽  
Defeng Zhao ◽  
Florian Rubach ◽  
Andreas Wahner ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Malonic Acid ◽  
Volume Fraction ◽  
Cloud Condensation Nuclei ◽  
Water Soluble ◽  
Coating Process ◽  
Condensation Nuclei ◽  
Mineral Particles ◽  
Acid Coating ◽  
Ccn Activity

Abstract. Condensation of carboxylic acids on mineral particles leads to coatings and impacts the particles' potential to act as cloud condensation nuclei (CCN). To determine how the CCN activity of mineral particles is impacted by carboxylic acid coatings, the CCN activities of CaCO3 particles and CaCO3 particles with oleic acid and malonic acid coatings were compared in this study. The results revealed that small amounts of oleic acid coating (volume fraction (vf) ≤4.3 %) decreased the CCN activity of CaCO3 particles, while more oleic acid coating (vf ≥16 %) increased the CCN activity of CaCO3 particles. This phenomenon has not been reported before. In contrast, the CCN activity of CaCO3 particles coated with malonic acid increased with the thickness of the malonic acid coating (vf =0.4–40 %). Even the smallest amounts of malonic acid coating (vf =0.4 %) significantly enhanced the CCN activity of CaCO3 particles from κ=0.0028±0.0001 to κ=0.0123±0.0005. This indicates that a small amount of water-soluble organic acid coating may significantly enhance the CCN activity of mineral particles. The presence of water vapor during the coating process with malonic acid additionally increased the CCN activity of the coated CaCO3 particles, probably because more CaCO3 reacts with malonic acid when sufficient water is available.

scholarly journals Impact of isolated atmospheric aging processes on the cloud condensation nuclei activation of soot particles

2019 ◽  
Vol 19 (24) ◽  
pp. 15545-15567 ◽  
Author(s):  
Franz Friebel ◽  
Prem Lobo ◽  
David Neubauer ◽  
Ulrike Lohmann ◽  
Saskia Drossaart van Dusseldorp ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Cloud Droplet ◽  
High Sensitivity ◽  
Condensation Nuclei ◽  
Soot Particles ◽  
Atmospheric Aging ◽  
Ccn Activity

Abstract. The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted into the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of 1 week, requiring tailored experiments that cover this time span. This work presents results on the ability of two types of soot, obtained using a miniCAST soot generator, to act as cloud condensation nuclei (CCN) after exposure to atmospherically relevant levels of ozone (O3) and humidity. Aging times of up to 12 h were achieved by successful application of the continuous-flow stirred tank reactor (CSTR) concept while allowing for size selection of particles prior to the aging step. Particles of 100 nm diameter and rich in organic carbon (OC) that were initially CCN inactive showed significant CCN activity at supersaturations (SS) down to 0.3 % after 10 h of exposure to 200 ppb of O3. While this process was not affected by different levels of relative humidity in the range of 5 %–75 %, a high sensitivity towards the ambient/reaction temperature was observed. Soot particles with a lower OC content required an approximately 4-fold longer aging duration to show CCN activity at the same SS. Prior to the slow change in the CCN activity, a rapid increase in the particle diameter was detected which occurred within several minutes. This study highlights the applicability of the CSTR approach for the simulation of atmospheric aging processes, as aging durations beyond 12 h can be achieved in comparably small aerosol chamber volumes (<3 m3). Implementation of our measurement results in a global aerosol-climate model, ECHAM6.3-HAM2.3, showed a statistically significant increase in the regional and global CCN burden and cloud droplet number concentration.

scholarly journals Impact of Isolated Atmospheric Aging processes on the Cloud Condensation Nuclei-activation of Soot Particles

2019 ◽  
Author(s):  
Franz Friebel ◽  
Prem Lobo ◽  
David Neubauer ◽  
Ulrike Lohmann ◽  
Saskia Drossaart van Dusseldorp ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
High Sensitivity ◽  
Condensation Nuclei ◽  
Soot Particles ◽  
Atmospheric Aging ◽  
Aerosol Chamber ◽  
Small Aerosol ◽  
Ccn Activity

Abstract. The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted to the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of one week, demanding tailored experiments that cover this time span. This work presents results on the ability of two types of soot to act as cloud condensation nuclei (CCN) after exposure to atmospherically relevant levels of ozone and humidity. Aging times of up to 12 h were achieved by successful application of the continuous-flow stirred tank reactor (CSTR) concept while allowing for size-selection of particles prior to the aging step. 100 nm particles rich in organic carbon (OC) that were initially CCN-inactive showed significant CCN-activity at supersaturations (SS) down to 0.3 % after 10 h of exposure to 200 ppb of ozone. While this process was not affected by different levels of relative humidity in the range 5–75 %, a high sensitivity towards the ambient/reaction temperature was observed. Soot particles with a lower OC-content demanded an approximately four-fold longer aging duration to show CCN-activity for the same SS. Prior to the slow change in the CCN-activity, a rapid increase in the particle diameter was detected which occurred within several minutes. This study highlights the applicability of the CSTR-approach for the simulation of atmospheric aging processes, as aging durations beyond 12 h can be achieved in comparably small aerosol chamber volumes (

scholarly journals Laboratory studies of the chemical composition and cloud condensation nuclei (CCN) activity of secondary organic aerosol (SOA) and oxidized primary organic aerosol (OPOA)

2011 ◽  
Vol 11 (17) ◽  
pp. 8913-8928 ◽  
Author(s):  
A. T. Lambe ◽  
T. B. Onasch ◽  
P. Massoli ◽  
D. R. Croasdale ◽  
J. P. Wright ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Cloud Condensation Nuclei ◽  
Oxidation Mechanism ◽  
Organic Aerosol ◽  
Anthropogenic Sources ◽  
Oh Radicals ◽  
Condensation Nuclei ◽  
Aerosol Mass ◽  
Ccn Activity

Abstract. Secondary organic aerosol (SOA) and oxidized primary organic aerosol (OPOA) were produced in laboratory experiments from the oxidation of fourteen precursors representing atmospherically relevant biogenic and anthropogenic sources. The SOA and OPOA particles were generated via controlled exposure of precursors to OH radicals and/or O3 in a Potential Aerosol Mass (PAM) flow reactor over timescales equivalent to 1–20 days of atmospheric aging. Aerosol mass spectra of SOA and OPOA were measured with an Aerodyne aerosol mass spectrometer (AMS). The fraction of AMS signal at m/z = 43 and m/z = 44 (f43, f44), the hydrogen-to-carbon (H/C) ratio, and the oxygen-to-carbon (O/C) ratio of the SOA and OPOA were obtained, which are commonly used to characterize the level of oxidation of oxygenated organic aerosol (OOA). The results show that PAM-generated SOA and OPOA can reproduce and extend the observed f44–f43 composition beyond that of ambient OOA as measured by an AMS. Van Krevelen diagrams showing H/C ratio as a function of O/C ratio suggest an oxidation mechanism involving formation of carboxylic acids concurrent with fragmentation of carbon-carbon bonds. Cloud condensation nuclei (CCN) activity of PAM-generated SOA and OPOA was measured as a function of OH exposure and characterized as a function of O/C ratio. CCN activity of the SOA and OPOA, which was characterized in the form of the hygroscopicity parameter κorg, ranged from 8.4×10−4 to 0.28 over measured O/C ratios ranging from 0.05 to 1.42. This range of κorg and O/C ratio is significantly wider than has been previously obtained. To first order, the κorg-to-O/C relationship is well represented by a linear function of the form κorg = (0.18±0.04) ×O/C + 0.03, suggesting that a simple, semi-empirical parameterization of OOA hygroscopicity and oxidation level can be defined for use in chemistry and climate models.

scholarly journals On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosols in the southeastern United States

2015 ◽  
Vol 15 (15) ◽  
pp. 8679-8694 ◽  
Author(s):  
K. M. Cerully ◽  
A. Bougiatioti ◽  
J. R. Hite ◽  
H. Guo ◽  
L. Xu ◽  
...  
Keyword(s):  
United States ◽  
Oxidation State ◽  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Southeastern United States ◽  
Organic Aerosols ◽  
Sampling Period ◽  
Water Soluble ◽  
Rural Site ◽  
Ccn Activity

Abstract. The formation of secondary organic aerosols (SOAs) combined with the partitioning of semivolatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity, and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in a rural site in the southeastern United States, a suite of instruments including a CCN counter, a thermodenuder (TD), and a high-resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity, aerosol volatility, composition, and oxidation state. Particles were either sampled directly from ambient or through a particle-into-liquid sampler (PILS), allowing the investigation of the water-soluble aerosol component. Ambient aerosols exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally denuded aerosols was similar between ambient and PILS-generated aerosols and showed limited dependence on volatilization. Results of AMS three-factor positive matrix factorization (PMF) analysis for the PILS-generated aerosols showed that the most hygroscopic components are most likely the most and the least volatile features of the aerosols. No clear relationship was found between organic hygroscopicity and the oxygen-to-carbon ratio; in fact, isoprene-derived organic aerosols (isoprene-OAs) were found to be the most hygroscopic factor, while at the same time being the least oxidized and likely most volatile of all PMF factors. Considering the diurnal variation of each PMF factor and its associated hygroscopicity, isoprene-OA and more-oxidized oxygenated organic aerosols are the prime contributors to hygroscopicity and co-vary with less-oxidized oxygenated organic aerosols in a way that induces the observed diurnal invariance in total organic hygroscopicity. Biomass burning organic aerosols contributed little to aerosol hygroscopicity, which is expected since there was little biomass burning activity during the sampling period examined.

scholarly journals Impact of aerosol composition on cloud condensation nuclei activity

2012 ◽  
Vol 12 (1) ◽  
pp. 1493-1516
Author(s):  
Q. Zhang ◽  
J. Meng ◽  
J. Quan ◽  
Y. Gao ◽  
D. Zhao ◽  
...  
Keyword(s):  
Size Distribution ◽  
Field Experiments ◽  
Cloud Condensation Nuclei ◽  
Diffusion Chamber ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Rate Of Increase ◽  
The Impact ◽  
Ccn Activity

Abstract. The impact of aerosol composition on cloud condensation nuclei (CCN) activity was analyzed in this study based on field experiments carried out at downtown Tianjin, China, in September 2010. In the experiments, the CCN measurements were performed at supersaturation (SS) of 0.1%, 0.2% and 0.4% using a thermal-gradient diffusion chamber (DMT CCNC), whereas the aerosol size distribution and composition were simultaneously measured with a TSI SMPS and an Aerodyne Aerosol Mass Spectrometer (AMS), respectively. The results show that the influence of aerosol composition on CCN activity is notable under low SS (0.1%), and their influence decreased with increasing SS. For example, under SS of 0.1%, the CCN activity increases from 4.5 ± 2.6% to 12.8 ± 6.1% when organics fraction decrease from 30–40% to 10–20%. The rate of increase reaches up to 184%. While under SS of 0.4%, the CCN activity increases only from 35.7 ± 19.0% to 46.5 ± 12.3%, correspondingly. The calculated NCCN based on the size-resolved activation ratio and aerosol number size distribution correlates well with observed NCCN at high SS (0.4%), but this correlation decreases with the falling of SS. The slopes of linear fitted lines between calculated and observed NCCN are 0.708, 0.947, and 0.995 at SS of 0.1%, 0.2% and 0.4%, respectively. Moreover, the standard deviation (SD) of calculated NCCN increases with the decreasing of SS. A case study of CCN closure analyses indicates that the calculated error of NCCN can reach up to 34% at SS of 0.1% if aerosol composition is not included, and the calculated error decreases with the raising of SS. It decreases to 9% at SS of 0.2%, and further decreases to 4% at SS of 0.4%.

scholarly journals On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosol in the Southeastern United States

2014 ◽  
Vol 14 (22) ◽  
pp. 30835-30877 ◽  
Author(s):  
K. M. Cerully ◽  
A. Bougiatioti ◽  
J. R. Hite Jr. ◽  
H. Guo ◽  
L. Xu ◽  
...  
Keyword(s):  
United States ◽  
Oxidation State ◽  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Southeastern United States ◽  
Sampling Period ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Rural Site ◽  
Ccn Activity

Abstract. The formation of secondary organic aerosol (SOA) combined with the partitioning of semi-volatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in a rural site in the Southeastern United States, a suite of instruments including a CCN counter, a thermodenuder (TD) and a high resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity, aerosol volatility, composition and oxidation state. Particles were either sampled directly from ambient or through a Particle Into Liquid Sampler (PILS), allowing the investigation of the water-soluble aerosol component. Ambient aerosol exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally-denuded aerosol was similar between ambient and PILS-generated aerosol and showed limited dependence on volatilization. Results of AMS 3-factor Positive Matrix Factorization (PMF) analysis for the PILS-generated aerosol showed that the most hygroscopic components are most likely the most and the least volatile features of the aerosol. No clear relationship was found between organic hygroscopicity and oxygen-to-carbon ratio; in fact, Isoprene organic aerosol (Isoprene-OA) was found to be the most hygroscopic factor, while at the same time being the least oxidized and likely most volatile of all PMF factors. Considering the diurnal variation of each PMF factor and its associated hygroscopicity, Isoprene-OA and More Oxidized – Oxidized Oxygenated Organic Aerosol (MO-OOA) are the prime contributors to hygroscopicity and covary with Less Oxidized – Oxidized Oxygenated Organic Aerosol (LO-OOA) in a way that induces the observed diurnal invariance in total organic hygroscopicity. Biomass Burning Organic Aerosol (BBOA) contributed little to aerosol hygroscopicity, which is expected since there was little biomass burning activity during the sampling period examined.

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