Abstract

The triple isotopic composition of oxygen (Δ17O) in sulfate and nitrate indicate the relative importance of oxidation pathways in their formation in the atmosphere. Ice core measurements of their isotopic composition can then provide insights into past changes in sulfate and nitrate chemistry. Due to the complexity of the isotopic system (e.g. multiple reactions can result in the same isotopic composition), quantitative interpretation is challenging, but has been aided by the application of paleo-atmospheric chemistry models ranging from box models to chemical transport models and coupled climate-chemistry models. I will present measurements and interpretation of both sulfate and nitrate isotopes from the WAIS Divide, Antarctica ice core spanning the past 2500 years [Sofen et al., ACPD , 2013] as well as new results from a coupled climate-chemistry model focused on glacial-interglacial changes in atmospheric chemistry in the context of existing sulfate Δ17O measurements from Vostok [Alexander et al., 2002].