Download Abstracts Here - IGAC Project

List of Abstracts 2344 IGAC Core Project Office, U. Washington5 Max Planck Institute for Chemistry6 Universidad de Chile7 University of Crete8 Université de CocodyContact: tzhu@pku.edu.cnWith increasing global population and continuous urbanization, in 2008, for the first time in human historyover half the world’s population resides in urban areas. In the mean time, the number of megacities (citieswith population over 10 million) has reached to 19 and expected to reach 27 in 2025. Megacities are theareas with the most intensive human activities; they impact on terrestrial and aquatic ecosystems, and aremajor sources of air pollutants and greenhouse gases, due to intensive economical and social activities aswell as energy consumption in megacities and their surrounding regions. It’s long been recognized that airpollution has negative impacts on human and ecosystem health. More recently, the role of anthropogenicemissions in altering climate has come to the fore. While the former has typically been considered a localissue and the latter global, they are linked through atmospheric concentrations of short-lived species such asaerosols and ozone. Experience of developed counties show that the pronounced air quality degradationaccompanied past development can be avoided. The scientific and engineering knowledge accumulated asearlier developing megacities dealt with their air quality problems is a significant resource for current andfuture developing megacities. With the growing trend towards urbanization, understanding the role ofmegacities in local to global atmospheric chemistry is critical to effectively addressing both of these issues.An assessment on the impacts of megacities on air quality and climate change will be presented. Theimportance of mega-cities as an emission source of global greenhouse gases and the impacts of megacitieson climate through emission and photochemical formation of ozone and aerosols will be discussed.Wake-up 1.4 ID:4239 10:15Atmospheric chemistry in volcanic plumesRoland Von GlasowSchool of Environmental Sciences, University of East AngliaContact: r.von-glasow@uea.ac.ukRecent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes arechemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneousreactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Keyfeatures of these measurements can be reproduced by numerical models such as the one employed in thisstudy. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozonedestruction, that, depending on plume dispersal, can be maintained for several days. The very highconcentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, sothat it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane involcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OHchemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the modelstudies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted withbromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercuryimplies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury tothe atmospheric background might be less than previously thought. However, the implications, especiallyhealth and environmental effects due to deposition, might be substantial and warrant further studies,especially field measurements to test this hypothesis.iCACGP-IGAC 2010 16 July, 2010