Geochemical characterization of millions of individual atmospheric particles entrapped in Antarctic ice across the last glacial-interglacial transition.

Reconstructing the source regions of past atmospheric dust preserved in ice remains a challenge in Antarctic glaciology. Until now, different dust properties were obtained by separate techniques and could not be directly correlated at single particle level limiting the dust characterization. Here we apply a novel technique (single particle Inductively Coupled Plasma-Time of Flight Mass Spectrometry) to characterize millions of individual particles in low-volume (< 2 mL) ice samples. We analyzed more than 2,000,000 individual particles smaller than 2.5 µm in 28 discrete samples from Taylor Glacier, coastal East Antarctica, spanning 44-9 kyr BP. We show a glacial-interglacial shift in particle number and mass concentrations, as well as in the elemental and mineralogical compositions. Our observations suggest a common potential dust source area for central and coastal East Antarctica during the Last Glacial Period, followed by a transition to different dominant sources in coastal sites during the Holocene. These changes likely reflect large-scale variations in dust sources, and environmental conditions in the Southern Hemisphere. We have also identified and measured the elemental composition of thousands of volcanic particles < 2.5 µm, indicating occasional tephra deposition from one of the Victoria Land volcanoes around 14.8 kyr BP.