SO2 oxidation and nucleation studies at near-atmospheric conditions in outdoor smog chamber

2013 ◽  
Vol 10 (3) ◽  
pp. 210 ◽  
Author(s):  
Yang Zhou ◽  
Elias P. Rosen ◽  
Haofei Zhang ◽  
Weruka Rattanavaraha ◽  
Wenxing Wang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Particle Growth ◽  
Particle Formation ◽  
Particle Nucleation ◽  
Smog Chamber ◽  
Atmospheric Conditions ◽  
So2 Oxidation ◽  
Phase Oxidation ◽  
Exponential Power

Environmental context Nucleation, a fundamental step in atmospheric new-particle formation, is a significant source of atmospheric aerosols. Most laboratory experiments investigate H2SO4 nucleation based on indoor chambers or flow tube reactors, and find discrepancies with field observations. Here a large outdoor smog chamber is used to study the relationship between SO2 and nucleation rates, and demonstrate the importance of aqueous phase oxidation of SO2 by H2O2 and other oxidants. Abstract Particle formation under different initial ambient background conditions was simulated in a dual outdoor smog chamber for the SO2 and O3–SO2 systems with and without sunlight, as well as a propylene–NOx–SO2–sunlight system. An exponential power of 1.37 between nucleation rates at 1nm (J1) and SO2 gas phase concentrations was obtained for the SO2–sunlight system and a minimum of 0.45ppbSO2 is required by this relationship to initiate nucleation (J1 is equal to 1cm–3s–1). An investigation of the O3–SO2–sunlight/dark system showed that the presence of O3 contributed to the particle nucleation and growth at night; however, it only enhanced the particle growth in the daytime when H2SO4 photochemistry was present. In the presence of an OH• scavenger, the O3–SO2 system did not show particle nucleation, suggesting that the scavenger cut off this pathway of SO2 oxidation. A lower nucleation rate and higher particle grow rate were also observed for SO2 oxidation in the presence of propylene and NOx. However a higher SO2 decay rate was obtained for the propylene system especially under high relative humidity, which was not observed in the O3–SO2 system. This suggests that aqueous phase oxidation of SO2 from H2O2, RO2• and other oxidants produced in the propylene–NOx system contribute to the particle growth.

scholarly journals Analysis of new particle formation (NPF) events at nearby rural, urban background and urban roadside sites

2019 ◽  
Vol 19 (8) ◽  
pp. 5679-5694 ◽  
Author(s):  
Dimitrios Bousiotis ◽  
Manuel Dall'Osto ◽  
David C. S. Beddows ◽  
Francis D. Pope ◽  
Roy M. Harrison
Keyword(s):  
Urban Environment ◽  
Growth Rates ◽  
General Pattern ◽  
Particle Growth ◽  
Particle Formation ◽  
Atmospheric Conditions ◽  
New Particle Formation ◽  
Urban Background ◽  
Air Masses ◽  
Condensation Sink

Abstract. New particle formation (NPF) events have different patterns of development depending on the conditions of the area in which they occur. In this study, particle size distributions in the range of 16.6–604 nm (7 years of data) were analysed and NPF events occurring at three sites of differing characteristics – rural Harwell (HAR), urban background North Kensington (NK), urban roadside Marylebone Road (MR), London, UK – were extracted and studied. The different atmospheric conditions in each study area not only have an effect on the frequency of the events, but also affect their development. The frequency of NPF events is similar at the rural and urban background locations (about 7 % of days), with a high proportion of events occurring at both sites on the same day (45 %). The frequency of NPF events at the urban roadside site is slightly less (6 % of days), and higher particle growth rates (average 5.5 nm h−1 at MR compared to 3.4 and 4.2 nm h−1 at HAR and NK respectively) must result from rapid gas-to-particle conversion of traffic-generated pollutants. A general pattern is found in which the condensation sink increases with the degree of pollution of the site, but this is counteracted by increased particle growth rates at the more polluted location. A key finding of this study is that the role of the urban environment leads to an increment of 20 % in N16–20 nm in the urban background compared to that of the rural area in NPF events occurring at both sites. The relationship of the origin of incoming air masses is also considered and an association of regional events with cleaner air masses is found. Due to lower availability of condensable species, NPF events that are associated with cleaner atmospheric conditions have lower growth rates of the newly formed particles. The decisive effect of the condensation sink in the development of NPF events and the survivability of the newly formed particles is underlined, and influences the overall contribution of NPF events to the number of ultrafine particles in an area. The other key factor identified by this study is the important role that pollution, both from traffic and other sources in the urban environment (such as heating or cooking), plays in new particle formation events.

scholarly journals Ion-induced nucleation of pure biogenic particles

Nature ◽  
2016 ◽  
Vol 533 (7604) ◽  
pp. 521-526 ◽  
Author(s):  
Jasper Kirkby ◽  
Jonathan Duplissy ◽  
Kamalika Sengupta ◽  
Carla Frege ◽  
Hamish Gordon ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Atmospheric Aerosols ◽  
Radiative Forcing ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Galactic Cosmic Rays ◽  
Binding Energies ◽  
Minor Role ◽  
Atmospheric Conditions

Abstract Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

scholarly journals Multiple daytime nucleation events in semi-clean savannah and industrial environments in South Africa: analysis based on observations

2013 ◽  
Vol 13 (11) ◽  
pp. 5523-5532 ◽  
Author(s):  
A. Hirsikko ◽  
V. Vakkari ◽  
P. Tiitta ◽  
J. Hatakka ◽  
V.-M. Kerminen ◽  
...  
Keyword(s):  
South Africa ◽  
Sulphuric Acid ◽  
Particle Growth ◽  
Particle Formation ◽  
Nucleation And Growth ◽  
Atmospheric Conditions ◽  
So2 Emissions ◽  
Rural Environments ◽  
Very High Frequencies ◽  
Growth Event

Abstract. Recent studies have shown very high frequencies of atmospheric new particle formation in different environments in South Africa. Our aim here was to investigate the causes for two or three consecutive daytime nucleation events, followed by subsequent particle growth during the same day. We analysed 108 and 31 such days observed in a polluted industrial and moderately polluted rural environments, respectively, in South Africa. The analysis was based on two years of measurements at each site. After rejecting the days having notable changes in the air mass origin or local wind direction, i.e. two major reasons for observed multiple nucleation events, we were able to investigate other factors causing this phenomenon. Clouds were present during, or in between most of the analysed multiple particle formation events. Therefore, some of these events may have been single events, interrupted somehow by the presence of clouds. From further analysis, we propose that the first nucleation and growth event of the day was often associated with the mixing of a residual air layer rich in SO2 (oxidized to sulphuric acid) into the shallow surface-coupled layer. The second nucleation and growth event of the day usually started before midday and was sometimes associated with renewed SO2 emissions from industrial origin. However, it was also evident that vapours other than sulphuric acid were required for the particle growth during both events. This was especially the case when two simultaneously growing particle modes were observed. Based on our analysis, we conclude that the relative contributions of estimated H2SO4 and other vapours on the first and second nucleation and growth events of the day varied from day to day, depending on anthropogenic and natural emissions, as well as atmospheric conditions.

scholarly journals Laboratory study on new particle formation from the reaction OH + SO<sub>2</sub>: influence of experimental conditions, H<sub>2</sub>O vapour, NH<sub>3</sub> and the amine tert-butylamine on the overall process

2010 ◽  
Vol 10 (15) ◽  
pp. 7101-7116 ◽  
Author(s):  
T. Berndt ◽  
F. Stratmann ◽  
M. Sipilä ◽  
J. Vanhanen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Particle Number ◽  
Particle Growth ◽  
Particle Formation ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Promoting Effect ◽  
Experimental Conditions ◽  
H2so4 Concentration ◽  
Tert Butylamine

Abstract. Nucleation experiments starting from the reaction of OH radicals with SO2 have been performed in the IfT-LFT flow tube under atmospheric conditions at 293±0.5 K for a relative humidity of 13–61%. The presence of different additives (H2, CO, 1,3,5-trimethylbenzene) for adjusting the OH radical concentration and resulting OH levels in the range (4–300) ×105 molecule cm−3 did not influence the nucleation process itself. The number of detected particles as well as the threshold H2SO4 concentration needed for nucleation was found to be strongly dependent on the counting efficiency of the used counting devices. High-sensitivity particle counters allowed the measurement of freshly nucleated particles with diameters down to about 1.5 nm. A parameterization of the experimental data was developed using power law equations for H2SO4 and H2O vapour. The exponent for H2SO4 from different measurement series was in the range of 1.7–2.1 being in good agreement with those arising from analysis of nucleation events in the atmosphere. For increasing relative humidity, an increase of the particle number was observed. The exponent for H2O vapour was found to be 3.1 representing an upper limit. Addition of 1.2×1011 molecule cm−3 or 1.2×1012 molecule cm−3 of NH3 (range of atmospheric NH3 peak concentrations) revealed that NH3 has a measureable, promoting effect on the nucleation rate under these conditions. The promoting effect was found to be more pronounced for relatively dry conditions, i.e. a rise of the particle number by 1–2 orders of magnitude at RH = 13% and only by a factor of 2–5 at RH = 47% (NH3 addition: 1.2×1012 molecule cm−3). Using the amine tert-butylamine instead of NH3, the enhancing impact of the base for nucleation and particle growth appears to be stronger. Tert-butylamine addition of about 1010 molecule cm−3 at RH = 13% enhances particle formation by about two orders of magnitude, while for NH3 only a small or negligible effect on nucleation in this range of concentration appeared. This suggests that amines can strongly influence atmospheric H2SO4-H2O nucleation and are probably promising candidates for explaining existing discrepancies between theory and observations.

Nighttime particle growth observed during spring in New Delhi: Evidences for the aqueous phase oxidation of SO2

2018 ◽  
Vol 188 ◽  
pp. 82-96 ◽  
Author(s):  
Bighnaraj Sarangi ◽  
Shankar G. Aggarwal ◽  
Bhagawati Kunwar ◽  
Sudhanshu Kumar ◽  
Ravleen Kaur ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Particle Growth ◽  
New Delhi ◽  
Phase Oxidation

scholarly journals Dynamic consideration of smog chamber experiments

2017 ◽  
Vol 17 (16) ◽  
pp. 10019-10036 ◽  
Author(s):  
Wayne K. Chuang ◽  
Neil M. Donahue
Keyword(s):  
Growth Rates ◽  
Peroxy Radical ◽  
Particle Growth ◽  
Equilibrium Analysis ◽  
Basis Set ◽  
Base Case ◽  
Particle Nucleation ◽  
Smog Chamber ◽  
Oxidation Rates ◽  
Chemical Conditions

Abstract. Recent studies of the α-pinene + ozone reaction that address particle nucleation show relatively high molar yields of highly oxidized multifunctional organic molecules with very low saturation concentrations that can form and grow new particles on their own. However, numerous smog-chamber experiments addressing secondary organic aerosol (SOA) mass yields, interpreted via equilibrium partitioning theory, suggest that the vast majority of SOA from α-pinene is semivolatile. We explore this paradox by employing a dynamic volatility basis set (VBS) model that reproduces the new-particle growth rates observed in the CLOUD experiment at CERN and then modeling SOA mass yield experiments conducted at Carnegie Mellon University (CMU). We find that the base-case simulations do overpredict observed SOA mass but by much less than an equilibrium analysis would suggest; this is because delayed condensation of vapors suppresses the apparent mass yields early in the chamber experiments. We further find that a second VBS model featuring substantial oligomerization of semivolatile monomers can match the CLOUD growth rates with substantially lower SOA mass yields; this is because the lighter monomers have a higher velocity and thus a higher condensation rate for a given mass concentration. The oligomerization simulations are a closer match to the CMU experiments than the base-case simulations, though they overpredict the observations somewhat. However, we also find that if the chemical conditions in CLOUD and the CMU chamber were identical, substantial nucleation would have occurred in the CMU experiments when in fact none occurred. This suggests that the chemical mechanisms differed in the two experiments, perhaps because the high oxidation rates in the SOA formation experiments led to rapid termination of peroxy radical chemistry.

scholarly journals Analysis of New Particle Formation (NPF) Events at Nearby Rural, Urban Background and Urban Roadside Sites

2018 ◽  
Author(s):  
Dimitrios Bousiotis ◽  
Manuel Dall’Osto ◽  
David C. S. Beddows ◽  
Francis D. Pope ◽  
Roy M. Harrison
Keyword(s):  
Growth Rates ◽  
Ultrafine Particles ◽  
General Pattern ◽  
Particle Growth ◽  
Particle Formation ◽  
Atmospheric Conditions ◽  
New Particle Formation ◽  
Urban Background ◽  
Air Masses ◽  
Condensation Sink

Abstract. NPF events have different patterns of development depending on the conditions of the area in which they occur. In this study, NPF events occurring at three sites of differing characteristics (rural Harwell (HAR), urban background North Kensington (NK), urban roadside Marylebone Road (MR), London, UK) were studied (seven years of data). The different atmospheric conditions in each study area not only have an effect on the frequency of the events, but also affect their development. The frequency of NPF events is similar at the rural and urban background locations (about 7 % of days), with a high proportion of events occurring at both sites on the same day (45 %). The frequency of NPF events at the urban roadside site is slightly less (6 % of days), and higher particle growth rates (average 5.5 nm h−1 at MR compared to 3.4 nm h−1 and 4.2 nm h−1 at HAR and NK respectively) must result from rapid gas to particle conversion of traffic-generated pollutants. A general pattern is found in which the condensation sink increases with the degree of pollution of the site, but this is counteracted by increased particle growth rates at the more polluted location. A key finding of this study is that the role of the urban environment leads to an increment of 20 % in N16–20 nm in the urban background compared to that of the rural area in NPF events occurring at both sites. The relationship of the origin of incoming air masses is also considered and an association of regional events with cleaner air masses is found. Due to lower availability of condensable species, NPF events that are associated with cleaner atmospheric conditions have lower growth rates of the newly formed particles. The decisive effect of the condensation sink in the development of NPF events and the survivability of the newly formed particles is underlined, and influences the overall contribution of NPF events to the number of ultrafine particles in an area. The other key factor identified by this study is the important role that urban pollution plays in new particle formation events.

scholarly journals Changes in the production rate of secondary aerosol particles in central Europe in view of decreasing SO<sub>2</sub> emissions between 1996 and 2006

2009 ◽  
Vol 9 (4) ◽  
pp. 15083-15123
Author(s):  
A. Hamed ◽  
W. Birmili ◽  
J. Joutsensaari ◽  
S. Mikkonen ◽  
A. Asmi ◽  
...  
Keyword(s):  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Formation Rate ◽  
Global Radiation ◽  
Particle Formation ◽  
Research Station ◽  
Particle Nucleation ◽  
Atmospheric Conditions ◽  
So2 Emissions

Abstract. In anthropogenically influenced atmospheres, sulphur dioxide (SO2) is the main precursor of gaseous sulphuric acid (H2SO4), which in turn forms new aerosol particles (diameter <10 nm) through nucleation. As a result of socio-economic changes, East Germany has seen a dramatic decrease in anthropogenic SO2 emissions between 1989 and present, as documented by routine air quality measurements in many locations. Using two different data sets of experimental particle number size distributions (3–750 nm) from the research station Melpitz (1996–1997 and 2003–2006) we have attempted to evaluate the possible influence of changing SO2 concentrations on the frequency and intensity of new particle formation (NPF). Between the two periods SO2 concentrations decreased on average by 65%, while the frequency of NPF events dropped by 45%. In addition, the average formation rate of 3 nm particles decreased by 68%. The trends were statistically significant, therefore suggesting a connection between the availability of anthropogenic SO2 and the production of new particle number. A contrasting finding was the increase in the mean growth rate of freshly nucleated particles (+22%), suggesting that particle nucleation and subsequent growth into larger sizes are delineated with respect to their precursor species. Using three basic parameters, the condensation sink for H2SO4, the SO2 concentration, and global radiation intensity, we could define the characteristic range of atmospheric conditions under which particle formation events at the Melpitz site take place or not. While the connection between anthropogenic SO2, H2SO4 and NPF appears very plausible, our analysis yielded no significant evidence whether decreasing SO2 concentrations did affect the production of cloud condensation nuclei (CCN).

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