Understanding Atmospheric Sulfur Cycle using Triple Isotopes of Oxygen and Sulfur (ASCTIOS)

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Sulfate is a significant chemical component of atmospheric aerosols; however, the chemistry governing its formation over a large portion of the globe, particularly the high latitudes and southern hemisphere remains unconstrained. At present there are sparse measurements of sulfur dioxide fluxes from anthropogenic and natural sources, particularly in the southern hemisphere. Sulfate aerosols interact strongly with incoming solar and outgoing terrestrial radiations by scattering and absorption, therefore size distribution is of high significance to understand the mode of interaction of sulfate aerosols with radiation. The primary objective of this study is to develop an isotopic probe of atmospheric sulfate chemistry in a pristine marine environment at Cape Grim Baseline Air Pollution Station, Australia to identify the role of sea salt alkalinity on the oxidation of sulfur. Oxygen and sulfur isotope measurements will be used to better constrain the sources and chemistry controlling the formation and transport of sulfate aerosol in the atmosphere. These results will be used to interpret paleo-sulfate aerosol data obtained from Antarctic ice cores and to identify the contribution of anthropogenic sulfur to the natural sulfur cycle.This research will help to elucidate the impact of sulfur chemistry on climate in a clean oceanic background at Cape Grim Station, Australia. This will establish a baseline for evaluating temporal and spatial variations in sulfate aerosols and will provide a basis for the future interpretation of ice core data. In view of the inherent problems associated with global chemistry models used to reproduce the sulfate levels, this new analytical tool has the potential to improve global chemistry models and in turn this may enable a better diagnosis of potential changes that result from anthropogenic sulfate sources. This project also has the broader goal of furthering the development of human resources in the field by training a postdoctoral scientist and graduate and undergraduate students.