MERCURY IN PRECIPITATED AND SURFACE SNOW AT DOME C, A FIRST ESTIMATE OF MERCURY DEPOSITIONAL FLU XES DURING THE AUSTRAL SUMMER ON THE HIGH ANTARCTIC PLATEAU .

Mercury is a pollutant of global concern. It enters both the terrestrial and aquatic ecosystems through atmospheric deposition. Via long range transport and re-cycling from the Earth's surfaces, mercury can reach the polar ice sheets. Mercury measurements in air and snow are fundamental in providing experimental data for regional and global scale chemistry models. Over the past few years, field mercury measurement campaigns of the polar atmosphere, surface snow and deposition as diamond dust, frost or rime have increased in both temporal and spatial coverage, providing important clues on the mercury chemical cycle and mechanisms of transport, deposition and re-emission at high latitudes. In this framework, we present measurements of mercury concentrations in both the surface snowpack and in precipitation (snow, diamond dust and frost) from Antarctica at Dome C, where the Italo-French Concordia Station is located at 75.10° S, 123.35° E. These samples were taken from the 11th December 2017 to the 20th January 2018, during the Austral summer. The surface snow sampling was carried out twice a day while the precipitation was sampled daily from an elevated bench. Mercury and bromine were measured in the surface snow samples while mercury alone was measured in the precipitation. All measurements were carried out by Inductively Coupled Plasma Sector Field Mass Spectroscopy (ICP-SFMS) after sample preparation in the clean room in Venice. Alongside the total mercury concentrations, we present the calculated mercury depositional fluxes, allowing constraints to be put on their values on the high Antarctic plateau. In addition, re-emission fluxes from the snow pack at Dome C will be estimated for the time period of our experiment. These are fundamental parameters for understanding the extent of mercury cycles and will help refine mercury chemistry models. Notable events are investigated by performing back trajectory atmospheric reanalysis using HYSPLIT and the relationship between deposition flux and precipitation type (snow, rime formation, diamond dust) have been looked at more closely.