Laboratory study on new particle formation from the reaction OH + SO2: influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process
Open Access
- 3 August 2010
- journal article
- Published by Copernicus GmbH in Atmospheric Chemistry and Physics
- Vol. 10 (15), 7101-7116
- https://doi.org/10.5194/acp-10-7101-2010
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.Keywords
This publication has 53 references indexed in Scilit:
- Observations of aminium salts in atmospheric nanoparticles and possible climatic implicationsProceedings of the National Academy of Sciences, 2010
- An improved parameterization for sulfuric acid–water nucleation rates for tropospheric and stratospheric conditionsJournal of Geophysical Research: Solid Earth, 2002
- Parametrization of ternary nucleation rates for H2SO4‐NH3‐H2O vaporsJournal of Geophysical Research: Solid Earth, 2002
- Measurement of prenucleation molecular clusters in the NH3, H2SO4, H2O systemJournal of Geophysical Research: Solid Earth, 2002
- Measurements of OH, H2SO4, and MSA at the South Pole during ISCATGeophysical Research Letters, 2001
- Ternary nucleation of H2SO4, NH3, and H2O in the atmosphereJournal of Geophysical Research: Solid Earth, 1999
- OH measurements during the First Aerosol Characterization Experiment (ACE 1): Observations and model comparisonsJournal of Geophysical Research: Solid Earth, 1998
- MEASURED ATMOSPHERIC NEW PARTICLE FORMATION RATES: IMPLICATIONS FOR NUCLEATION MECHANISMSChemical Engineering Communications, 1996
- A preliminary study of the effect of ammonia on particle nucleation in the marine boundary layerJournal of Geophysical Research: Solid Earth, 1995
- Recombination Reactions in Atmospheric ChemistryBerichte der Bunsengesellschaft für physikalische Chemie, 1978