Interactive comment on “The role of ions in new-particle formation in the CLOUD chamber” by Robert Wagner

Abstract. Aerosol physical and chemical properties and trace gas concentrations were measured during the QUEST field campaign in March–April 2003, in Hyytiälä, Finland. Our aim was to understand the role of oxidation products of VOC's such as mono- and sesquiterpenes in atmospheric nucleation events. Particle chemical compositions were measured using the Aerodyne Aerosol Mass Spectrometer, and chemical compositions of aerosol samples collected with low-pressure impactors and a high volume sampler were analysed using a number of techniques. The results indicate that during and after new particle formation, all particles larger than 50 nm in diameter contained similar organic substances that are likely to be mono- and sesquiterpene oxidation products. The oxidation products identified in the high volume samples were shown to be mostly aldehydes. In order to study the composition of particles in the 10–50 nm range, we made use of Tandem Differential Mobility Analyzer results. We found that during nucleation events, both 10 and 50 nm particle growth factors due to uptake of ethanol vapour correlate strongly with gas-phase monoterpene oxidation product (MTOP) concentrations, indicating that the organic constituents of particles smaller than 50 nm in diameter are at least partly similar to those of larger particles. We furthermore showed that particle growth rates during the nucleation events are correlated with the gas-phase MTOP concentrations. This indicates that VOC oxidation products may have a key role in determining the spatial and temporal features of the nucleation events. This conclusion was supported by our aircraft measurements of new 3–10 nm particle concentrations, which showed that the nucleation event on 28 March 2003, started at the ground layer, i.e. near the VOC source, and evolved together with the mixed layer. Furthermore, no new particle formation was detected upwind away from the forest, above the frozen Gulf of Bothnia.

Download Full-text

Modeling the possible role of iodine oxides in atmospheric new particle formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-505-2006 ◽

2006 ◽

Vol 6 (2) ◽

pp. 505-523 ◽

Cited By ~ 69

Author(s):

S. Pechtl ◽

E. R. Lovejoy ◽

J. B. Burkholder ◽

R. von Glasow

Keyword(s):

Marine Boundary Layer ◽

Hot Spot ◽

Coastal Region ◽

Particle Growth ◽

Particle Formation ◽

Surface Fluxes ◽

Laboratory Model ◽

New Particle Formation ◽

Iodine Oxides

Abstract. We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I) chemistry. We included a two-step nucleation parameterization, where in the first step, the "real" nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the "apparent" nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors) and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei. According to our studies, observations of particle "bursts" can only be explained by hot spot-like, not by homogeneously distributed emissions.

Download Full-text

Modeling the possible role of iodine oxides in atmospheric new particle formation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-5-9907-2005 ◽

2005 ◽

Vol 5 (5) ◽

pp. 9907-9952 ◽

Cited By ~ 2

Author(s):

S. Pechtl ◽

E. R. Lovejoy ◽

J. B. Burkholder ◽

R. von Glasow

Keyword(s):

Marine Boundary Layer ◽

Hot Spot ◽

Coastal Region ◽

Particle Growth ◽

Particle Formation ◽

Surface Fluxes ◽

Laboratory Model ◽

New Particle Formation ◽

Iodine Oxides

Abstract. We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I) chemistry. We included a two-step nucleation parameterization, where in the first step, the ''real'' nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the ''apparent'' nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors) and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei itself. According to our studies, observations of particle ''bursts'' can only be explained by hot spot-like, not by homogeneously distributed emissions.

Download Full-text

Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

10.5194/amt-2020-494 ◽

2020 ◽

Author(s):

Mingyi Wang ◽

Xu-Cheng He ◽

Henning Finkenzeller ◽

Siddharth Iyer ◽

Dexian Chen ◽

...

Keyword(s):

Sulfuric Acid ◽

Chemical Ionization ◽

Detection Limits ◽

Particle Formation ◽

Cloud Chamber ◽

Ionization Mass ◽

New Particle Formation ◽

Reduced Pressure ◽

Mass Spectrometers ◽

Iodine Species

Abstract. Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of bromide chemical ionization mass spectrometers (Br-CIMS) to this task. During iodine new-particle formation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and inter-comparisons with other instruments attached to the CLOUD chamber, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I2, and H2SO4 and obtain detection limits of 5.8 × 106, 6.3 × 105, and 2.0 × 105 molec cm−3, respectively, for a 2-min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 × 105 molec cm−3, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around one order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 × 107 and 5.1 × 106 molec cm−3, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

Download Full-text

The Role of Organic Acids in New Particle Formation from Methanesulfonic Acid and Methylamine

10.5194/acp-2021-831 ◽

2021 ◽

Author(s):

Rongjie Zhang ◽

Jiewen Shen ◽

Hong-Bin Xie ◽

Jingwen Chen ◽

Jonas Elm

Keyword(s):

Organic Acids ◽

Cluster Formation ◽

Methanesulfonic Acid ◽

Particle Formation ◽

Structural Factors ◽

Atmospheric Conditions ◽

New Particle Formation ◽

Free Energies ◽

Limited Temperature

Abstract. Atmospheric organic acids (OAs) are expected to enhance methanesulfonic acid (MSA)-driven new particle formation (NPF). However, the exact role of OAs in MSA-driven NPF remains unclear. Here, we employed a two-step strategy to probe the role of OAs in MSA-methylamine (MA) NPF. Initially, we evaluated the enhancing potential of 12 commonly detected OAs in ternary MA-MSA-OA cluster formation by considering the formation free energies of the (MSA)1(MA)1(OA)1 clusters and the atmospheric concentrations of the OAs. It was found that formic acid (ForA) has the highest potential to stabilize the MA-MSA clusters. The high enhancing potential of ForA results from its acidity, structural factors such as no intramolecular H-bonds and high atmospheric abundance. The second step is to extend the MSA-MA-ForA system to larger cluster sizes. The results indicate that ForA can indeed enhance MSA-MA NPF at atmospheric conditions (the upper limited temperature is 258.15 K), indicating that ForA might have an important role in MSA-driven NPF. The enhancing effect of ForA is mainly caused by an increased formation of the (MSA)2(MA)1 cluster, which is involved in the pathway of binary MSA-MA nucleation. Hence, our results indicate that OAs might be required to facilitate MSA-driven NPF in the atmosphere.

Download Full-text

Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-24165-2011 ◽

2011 ◽

Vol 11 (8) ◽

pp. 24165-24189 ◽

Cited By ~ 2

Author(s):

Z. B. Wang ◽

M. Hu ◽

D. L. Yue ◽

J. Zheng ◽

R. Y. Zhang ◽

...

Keyword(s):

Sulfuric Acid ◽

Particle Number ◽

Particle Formation ◽

Urban Atmosphere ◽

Limiting Factors ◽

New Particle Formation ◽

H2so4 Concentration ◽

Nucleation Mechanisms ◽

Better Than

Abstract. New particle formation (NPF) is considered as an important mechanism for gas-to-particle transformation, and gaseous sulfuric acid is believed as a curcial precursor. Up to now few field-based studies on nucleation mechanisms and the role of sulfuric acid were conducted in China. In this study, simultaneously measurements of particle number size distributions and gaseous sulfuric acid concentrations were performed from July to September in 2008. Totally, 22 new particle formation events were observed during the entire 85 campaign days. The results show that the condensation sink of pre-existing particles is one of the limiting factors to determine the occurrence of nucleation events in Beijing. The concentrations of gaseous sulfuric acid show good correlations with freshly nucleated particles (N3–6) and formation rates (J3 and J1.5). The power-law relationship between H2SO4 concentration and N3–6 or J was adopted to explore the nucleation mechanism. The exponents range from 1 to 5. More than half of the NPF events exhibit an exponent larger than 2.5. For these cases, the thermodynamic process works better than the activation or kinetic nucleation theories to explain the nucleation events in urban atmosphere of Beijing.

Download Full-text

The roles of sulfuric acid in new particle formation and growth in the mega-city of Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4953-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 4953-4960 ◽

Cited By ~ 136

Author(s):

D. L. Yue ◽

M. Hu ◽

R. Y. Zhang ◽

Z. B. Wang ◽

J. Zheng ◽

...

Keyword(s):

Sulfuric Acid ◽

Organic Compounds ◽

Dominant Role ◽

Formation Rate ◽

Particle Growth ◽

Particle Formation ◽

New Particle Formation ◽

Average Formation ◽

Subsequent Neutralization

Abstract. Simultaneous measurements of gaseous sulfuric acid and particle number size distributions were performed to investigate aerosol nucleation and growth during CAREBeijing-2008. The analysis of the measured aerosols and sulfuric acid with an aerosol dynamic model shows the dominant role of sulfuric acid in new particle formation (NPF) process but also in the subsequent growth in Beijing. Based on the data of twelve NPF events, the average formation rates (2–13 cm−3 s−1) show a linear correlation with the sulfuric acid concentrations (R2=0.85). Coagulation seems to play a significant role in reducing the number concentration of nucleation mode particles with the ratio of the coagulation loss to formation rate being 0.41±0.16. The apparent growth rates vary from 3 to 11 nm h−1. Condensation of sulfuric acid and its subsequent neutralization by ammonia and coagulation contribute to the apparent particle growth on average 45±18% and 34±17%, respectively. The 30% higher concentration of sulfate than organic compounds in particles during the seven sulfur-rich NPF events but 20% lower concentration of sulfate during the five sulfur-poor type suggest that organic compounds are an important contributor to the growth of the freshly nucleated particles, especially during the sulfur-poor cases.

Download Full-text