Barbara Delmonte

Coherent composition of glacial dust on opposite sides of the East Antarctic Plateau inferred from the deep EPICA ice cores

[1]xa0The dust provenance identification through isotopic and geochemical tracers focused mostly on ice cores drilled in the Pacific-Indian sector of Antarctica, where a common provenance of dust from Southern South America during glacial ages was demonstrated. Conversely, in other areas of the East Antarctic Plateau as Dronning Maud Land provenance was deduced indirectly from back trajectory analyses and soluble chemistry records. In this work, we present the first comparison of major elemental composition of dust archived in two ice cores from opposite sides of Antarctica, in the framework of the EPICA Project. Mineral particles extracted from the EDC and EDML cores date back to glacial MIS 2, 4 and 6, over the last 200 kyr. Results reveal a coherent geochemical dust composition at both locations, providing experimental evidence of a common provenance over the wide area of East Antarctica during glacials, and key analytical constrains for atmospheric general circulation models.

Prominent features in isotopic, chemical and dust stratigraphies from coastal East Antarctic ice sheet (Eastern Wilkes Land)

In this work we present the isotopic, chemical and dust stratigraphies of two snow pits sampled in 2013/14xa0at GV7 (coastal East Antarctica: 70°41 S - 158°51 E, 1950 m a.s.l.). A large number of chemical species are measured aiming to study their potentiality as environmental changes markers. Seasonal cluster backward trajectories analysis was performed and compared with chemical marker stratigraphies. Sea spray aerosol is delivered to the sampling site together with snow precipitation especially in autumn-winter by air masses arising from Western Pacific Ocean sector. Dust show maximum concentration in spring when the air masses arising from Ross Sea sector mobilize mineral dust from ice-free areas of the Transantarctic mountains. The clear seasonal pattern of sulfur oxidized compounds allows the dating of the snow-pit and the calculation of the mean accumulation rate, which is 242xa0±xa071xa0mm w.e. for the period 2008-2013. Methanesulfonic acid and NO3- do not show any concentration decreasing trend as depth increases, also considering a 12xa0m firn core record. Therefore these two compounds are not affected by post-depositional processes at this site and can be considered reliable markers for past environmental changes reconstruction. The rBC snow-pit record shows the highest values in summer 2012 likely related to large biomass burning even occurred in Australia in this summer. The undisturbed accumulation rate for this site is demonstrated by the agreement between the chemical stratigraphies and the annual accumulation rate of the two snow-pits analysed in Italian and Korean laboratories.