Variable Hf-Sr-Nd Radiogenic Isotopic Compositions in a Saharan Dust Storm over the Atlantic: Implications for Dust Flux to Oceans, Ice Sheets and the Terrestrial Biosphere

Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geology or Earth and Environmental Sciences, Department of Earth and Environmental SciencesIsotopic characterization of aerosol mineral particles (atmospheric dust) of varying sizes is essential in classifying source areas, and for determining the source of dust deposited over oceans and icesheets. However, the e_ect of atmospheric transport on radiogenic isotopic compositions is not well constrained, making provenance interpretation di_cult. In order to investigate the isotopic variability of 176Hf/177Hf, 87Sr/86Sr and 143Nd/144Nd we analyzed eight airborne dust samples in two size fractions collected along a cross-Atlantic transect through a dust storm originating in the Sahara in late 2002. Past measurements of 176Hf/177Hf, 87Sr/86Sr and 143Nd/144Nd of dust have focused primarily on coarse sized particles (<30 _m), whereas far field deposition is primarily finer particles (