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List of Abstracts 160Simulations with emissions exclusively from East-Asia will also be presented to show the effects of thesechanges on the trans-Pacific transport of mercury.P-Transformation.71 ID:4336 10:30Mercury Oxidation by OH and Ozone: combined measurement and modelling studies in a high ozoneenvironment suggest they play a very minor roleIan M. Hedgecock, Franco Cofone, Gianluca Manna, Nicola Pirrone, Francesca SprovieriCNR - Institute of Atmospheric Pollution Research, ItalyContact: i.hedgecock@iia.cnr.itIn light of the recent interest in mercury as a global scale pollutant, and the ongoing debate as to its majoroxidation pathways in the atmosphere, numerous kinetic, modelling and field studies have been carried outover the last ten to fifteen years. Mercury's lifetime is long enough for it to be found in the atmosphere andenvironment in remote areas such as the Arctic and Antarctica. The major removal process for mercury fromthe atmosphere is oxidation to Hg(II), which is more soluble than Hg(0), and subsequent scavenging via wetdeposition processes. Which oxidants are responsible has been the subject of not a little debate, although it isnow clear from observations, and modelling, of Arctic atmospheric mercury depletion events that Brcontainingcompounds do oxidise Hg in the atmosphere. The role of ozone and the OH radical is less certain;laboratory measurements suggest they both oxidise gas phase Hg(0), but the published rates vary and the gasphase products, if any, have not been unequivocally identified. Using data from a number of cruisemeasurements in the Mediterranean MBL between 2000 and 2009, the possible formation of Hg(II) fromboth ozone and OH has been studied. The Mediterranean MBL, particularly in the summertime provides anideal environment to study these reactions due to the consistently high ozone concentrations, and high solarradiation intensity – during some cruises the average concentration of ozone was over 60 ppb. The diurnalvariation seen in gas phase Hg(II) concentration in the MBL is completely irreproducible if OH or ozone areassumed to give gas phase products on reaction with Hg, however high concentrations of Hg associated withparticulate matter were not observed, suggesting that the role of these oxidants in the atmospheric cycling ofHg is grossly overestimated.P-Transformation.72 ID:4392 10:30Estimating the contribution of shipping emissions to high ozone concentrations during a summeranticyclone in the Mediterranean MBLIan M. Hedgecock 1 , Christian N. Gencarelli 2 , Gregor J. Schürmann 3 , Franco Cofone 1 , Gianluca Manna 1 ,Nicola Pirrone 1 , Francesca Sprovieri 11 CNR - Institute of Atmospheric Pollution Research, Italy2 Department of Physics, UNICAL / CNR - Institute of Atmospheric Pollution Research, Italy3 CNR - Institute of Atmospheric Pollution Research, Italy, now MPI for Biogeochemistry, Jena, GermanyContact: i.hedgecock@iia.cnr.itDuring the summer of 2005 the Italian Research Council R.V. Urania a performed series of atmosphericmeasurements along a route from Naples, south through the Strait of Messina, around the southern tip ofItaly and then north through the Adriatic to the Gulf of Trieste and back again. The average ozoneconcentration during the entire measurement campaign was over 60 ppb, with some daytime peaksexceeding 100ppb. As part of a ongoing systematic investigation of the sources contributing to these highozone concentrations the WRF-Chem model has been used to investigate the influence of different emissionsource categories on the regional ozone concentration. The model has been used with an outer domaincovering most of northern Europe and all of the Mediterranean (81 by 81 km) and a nested domain (27 by 27iCACGP-IGAC 2010 14 July, 2010