Κατανομή του DMS και των προϊόντων οξείδωσης του στην ατμόσφαιρα με έμφαση στο ρόλο των ετερογενών αντιδράσεων

• Main Authors: Bardouki, Haido, Μπαρδούκη, Χάιδω
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: University of Crete (UOC) 2003
• Subjects: Ατμόσφαιρα; Ατμοσφαιρικά αερολύματα; Κύκλος του θείου; Οξείδωση του SO2; Ανάκλαση συννεφών; Παραγωγή διμεθυλοσουλφιδίου; Οξείδωση διμεθυλοσουλφιδίου; DMS; Φυσικές Επιστήμες; Χημεία; Γεωεπιστήμες και Επιστήμες Περιβάλλοντος; Natural Sciences; Chemical Sciences; Earth and Related Environmental Sciences; Kuujjuarapik
• Online Access: http://hdl.handle.net/10442/hedi/33458; https://doi.org/10.12681/eadd/33458

Oceanic dimethylsulfide (DMS) emission is proposed to play a key role in climate regulation, through its oxidation products, especially in the remote marine atmosphere. Once emitted into the atmosphere DMS can be oxidized by OH, NO3 and possibly other radical species as BrO radicals forming a variety of products such as SO2, MSA and DMSO. The proposed climatic impact of DMS is decisively determined from the formation of new hydroscopic sulfate particles that either scattersolar radiation or act as cloud condensation nuclei (CCN) influencing the earth’s albedo and climate. The complete mechanism of DMS oxidation is still under investigation although considerable effort has been made during the last decades to clarify its oxidation scheme via field measurements, kinetic experiments and model results. In the present study, kinetics and product distribution of the reaction of DMSO and MSI- with OH radicals and H2O2 in the aqueous phase had been investigated. DMSO was found to be very stable in pure water or in solutions containing H2O2. Onthe other hand, the reaction with OH radicals was found to be very rapid (k = 4.5 x 109 M-1 s -1). MSI- has been identified as the main intermediate product, while MS- and sulfate were the final products due to the very fast reaction of MSI- with OH radicals (k = 1.2 x 1010 M-1 s -1). MS- has been identified as the major end product (yield higher than 95%) of both DMSO and MSI- reactions by OH radicals in aqueous solutions. Reactions of both DMSO and MSI- with OH radicals seem to be very important for the atmosphere, since the calculated lifetime range from few minutes to almost 1 h. Especially for DMSO, the liquid phase reaction with OH radicals seems to be more important compared to the gaseous phase reaction with the same radical. In the second part of this study, an effort was made to confirm the results from the kinetic lab experiment in the filed. Campaigns had been conducted in three locations of the planet: at Finokalia, Greece (35.24 0 N, 25.60 0 E), Kuujjuarapik, Canada ...