An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory

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dc.contributor.advisor Sodeau, John R. Townsend, Thomas Michael 2011-01-27T13:19:24Z 2013-07-16T21:06:33Z 2009 2009 2009
dc.identifier.citation Townsend, T. M., 2009. An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory. PhD Thesis, University College Cork. en
dc.description.abstract This thesis describes a broad range of experiments based on an aerosol flow-tube system to probe the interactions between atmospherically relevant aerosols with trace gases. This apparatus was used to obtain simultaneous optical and size distribution measurements using FTIR and SMPS measurements respectively as a function of relative humidity and aerosol chemical composition. Heterogeneous reactions between various ratios of ammonia gas and acidic aerosols were studied in aerosol form as opposed to bulk solutions. The apparatus is unique, in that it employed two aerosol generation methods to follow the size evolution of the aerosol while allowing detailed spectroscopic investigation of its chemical content. A novel chemiluminescence apparatus was also used to measure [NH4+]. SO2.H2O is an important species as it represents the first intermediate in the overall atmospheric oxidation process of sulfur dioxide to sulfuric acid. This complex was produced within gaseous, aqueous and aerosol SO2 systems. The addition of ammonia, gave mainly hydrogen sulfite tautomers and disulfite ions. These species were prevalent at high humidities enhancing the aqueous nature of sulfur (IV) species. Their weak acidity is evident due to the low [NH4+] produced. An increasing recognition that dicarboxylic acids may contribute significantly to the total acid burden in polluted urban environments is evident in the literature. It was observed that speciation within the oxalic, malonic and succinic systems shifted towards the most ionised form as the relative humidity was increased due to complete protonisation. The addition of ammonia produced ammonium dicarboxylate ions. Less reaction for ammonia with the malonic and succinic species were observed in comparison to the oxalic acid system. This observation coincides with the decrease in acidity of these organic species. The interaction between dicarboxylic acids and ‘sulfurous’/sulfuric acid has not been previously investigated. Therefore the results presented here are original to the field of tropospheric chemistry. SHO3-; S2O52-; HSO4-; SO42- and H1,3,5C2,3,4O4-;C2,3,4O4 2- were the main components found in the complex inorganic-organic systems investigated here. The introduction of ammonia produced ammonium dicarboxylate as well as ammonium disulfite/sulfate ions and increasing the acid concentrations increased the total amount of [NH4+]. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights ©2009, Thomas M. Townsend. en
dc.rights.uri en
dc.subject Acidic aerosols en
dc.subject Ammonia en
dc.subject Laboratory en
dc.subject Flow-tube en
dc.subject.lcsh Tropospheric chemistry en
dc.subject.lcsh Aerosols en
dc.title An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD Science - Chemistry en
dc.internal.availability Full text available en
dc.description.version Accepted Version en
dc.contributor.funder Higher Education Authority en
dc.description.status Not peer reviewed en Chemistry en

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©2009, Thomas M. Townsend. Except where otherwise noted, this item's license is described as ©2009, Thomas M. Townsend.
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