The Atmospheric Chemistry of Iodine and Alkenes

Chemical processing affects atmospheric composition, air quality and climate. The aim of this project is to characterise selected reactions of halogen species (iodine oxides), and alkene-ozone reactions, which are important, but poorly understood, components of the atmospheric system. Reactions of iodine species, released from marine sources, can lead to "ozone depletion events", when local ozone levels drop to zero in a few hours. Attempts to simulate the observed ozone loss with models frequently fail, as details of many of the reactions occurring are not known. The aim of this project is to study these reactions in the laboratory, using a new laser photolysis / UV-visible absorption spectroscopy approach, with a particular aim of understanding why iodine levels seem to be unaffected by local pollution (NOx emissions), contrary to model predictions. In the case of alkene-ozone reactions, these have recently been shown to produce “Criegee Intermediates”, CIs, which can reduce atmospheric SO2 levels (affecting air quality and climate). The aim of the work will be to measure the absorption cross sections of selected CIs, using time-resolved UV-visible absorption spectroscopy, and so constrain their fate in the atmosphere. This project will link laboratory measurements with atmospheric models (for interpretation of the data obtained); however it is likely that the researcher will also have the opportunity to participate in related field measurement activities during the course of their studies. The project will be supervised by Dr Bloss (see www.atmos.bham.ac.uk) and will be able to collaborate with colleagues whose interests span environmental chemistry, meteorology, climatology, atmospheric chemistry and air quality.