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Formation and control of atmospheric aerosol and nitric acid


Russell, Armistead Goode (1985) Formation and control of atmospheric aerosol and nitric acid. Dissertation (Ph.D.), California Institute of Technology.


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This work focuses on the formation, transport and control of atmospheric nitric acid and nitrate aerosol using both theoretical modeling and experimental techniques. A mathematical model was developed that describes the formation and transport of photochemically produced atmospheric gases and nitrate aerosol, using fundamental thermodynamic data to determine the quantity and state of the aerosol nitrate produced. Model predictions compared favorably with the field data available. A sensitivity study of the model indicated that the predicted aerosol nitrate concentrations are highly dependent on temperature. The trajectory model was used to study the fate of nitrogen oxides emissions and the chemical reactions responsible for the formation of atmospheric nitric acid. A majority of the [...] emissions deposit out within 24 hours, primarily as [...]. Previously it was believed that almost all of the atmospheric nitric acid was produced during daylight hours, however model results indicate that nighttime reactions can produce comparable quantities, especially in the upper portions of the boundary layer more than a hundred meters above ground.

An experimental program was designed and executed to collect a set of data for use in studying nitrate formation, and for use in evaluating the accuracy of air quality models. A large quantity of aerosol nitrate was observed to accumulate overnight near the coast, presumably due to the reaction between HNO3 and sea salt aerosol or soil dust—like material. This aerosol is then transported inland the following afternoon, and can contribute to the high particulate nitrate levels found inland. Data from the experiment were used to test the hypothesis that atmospheric [...] and [...] are in equilibrium with the aerosol phase. Most of the data are consistent with the assumption that an external mixture containing some pure [...] is present. Additional improvement is obtained if an internally mixed [...] aerosol is assumed to be present.

Further evaluation of the air quality model against the data described above showed that the model accurately predicts the measured concentrations of [...], [...], total nitrate, [...], and [...]. Representative emission control programs were tested using the model, and results indicated that [...] emission control will reduce [...], aerosol nitrate and PAN concentrations. For the particular trajectories studied, [...] control would also have reduced the peak [...] concentrations. Reducing [...] emissions will reduce aerosol nitrate formation at the expense of increasing [...] concentrations. Controlling organic gas emissions will reduce [...] and PAN. Further research areas suggested by this work also are presented.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Major Option:Mechanical Engineering
Thesis Availability:Restricted to Caltech community only
Thesis Committee:
  • Cass, Glen Rowan (chair)
Defense Date:8 January 1985
Record Number:CaltechETD:etd-03252008-090855
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1118
Deposited By: Imported from ETD-db
Deposited On:04 Apr 2008
Last Modified:26 Dec 2012 02:35

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