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| Identifier |
000337266 |
| Title |
Μελέτη του μηχανισμού σχηματισμού ενώσεων θείου στη σωματιδιακή φάση στην Ανατολική Μεσόγειο |
| Alternative Title |
Study of the formation of particulate sulfur species over the Eastern Mediterranean |
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Author
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Τζιτζικαλάκη, Ευαγγελία Ν
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Thesis advisor
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Κανακίδου, Μαρία
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| Abstract |
The goal of this study is to improve our understanding on the mechanism of particulate sulfate (SO42-) formation and methanosulfonate (MS-) in the Eastern Mediterranean and to evaluate the seasonal variability and the mechanism of particulate sulfure formation in the area. For this reason, a chemical box model coupled offline with an aerosol-cloud model has been used. The chemical box model is an Eulerian model, appropriate for simulations of the total particulate mass and the aerosol model is a Lagrangian model capable of simulating size-segregating mass distribution of aerosols.
Sulfur compounds vary seasonally in the Eastern Mediterranean. The highest values occur during summer and the lowest values occur during winter. There is a good agreement between measurements and simulations for the methanosulfonic acid (MSA) in the gas phase, when the yield of gaseous MSA from the OH-initiated oxidation of dimethylsulfide (DMS) is assumed to be 0.3%. The condensation of MSA produced from gas-phase oxidation of DMS on particles is too small to explain the observed levels of MS-. On the other hand, heterogeneous reactions of dimethyl sulfoxide (DMSO) and methanesufinic acid (MSIA) can account for the observed MS- levels. Since the 96% of the production of MS- can be attributed to heterogeneous reactions.
Marine biogenic sulfur emissions contribute 3 to 20% to the total oxidized sulphur production. The highest contribution occurs in summer and the lowest in winter.
Aerosol model simulations show that observed submicron nss-SO42- levels can be fully explained by homogeneous gas-phase oxidation of sulphur dioxide (SO2) to sulphuric acid H2SO4 which is subsequently scavenged by aerosol particles. On the other hand, only about 10% of the supermicron nss-SO42- can be explained by condensation of the gas-phase H2SO4, the rest is formed by heterogeneous reactions.
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| Language |
Greek |
| Subject |
Σωματίδια |
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αερολύματα |
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μοντέλο 0-διαστάσεων |
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ρύθμιση κλίματος |
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χημικός μηχανισμός |
| Issue date |
2008-07-22 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
194 |
Μελέτη του μηχανισμού σχηματισμού ενώσεων θείου στη σωματιδιακή φάση στην Ανατολική Μεσόγειο
