Identification of the Chemical Mechanisms of Heterogeneous Processes on Sea Salt Particles Using Stable Chlorine Isotope Ratios

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Abstract ATM-9529451 Wahlen, Martin University of California, San Diego Title: Identification of the Chemical Mechanisms of Heterogeneous Processes on Sea Salt Particles Using Stable Chlorine Isotope Ratios Field and laboratory and laboratory evidence indicates that significant quantities of sea salt chloride are volatilized by one or more chemical pathways other than desorption of hydrochloric acid following reaction with nitric or sulfuric acid. Laboratory experiments indicate that heterogeneous reactions can occur between sodium chloride and reactive atmospheric species such as nitrogen oxides and ozone, however, the prevalence of these reactions in the lower troposphere is still not understood. The primary objective of this project is to use stable chlorine isotopes ratios to support or dismiss reactions potentially responsible for chlorine volatilization throughout the world's oceans. The isotopic ratios are altered during chemical reactions where covalent bonds are formed or broken. Thus, different chemical reactions lead to different isotopic signatures. Measured isotopic fractionation in residual salt particles can be compared to the fractionation factors of the reactions simulated in the laboratory. In this project, laboratory investigations will be carried out in collaboration with Prof. Jonathan Abbatt at the University of Chicago to determine the isotopic fractionation factors of individual volatilization reactions. In addition, archived aeroslo samples from various oceanic regions will be analyzed for chlorine fractionation, From this information, the heterogeneous processes responsible for chlorine volatilization in the aerosols will be determined.