Final conference, Rome October 11, 2016 Chemical evolution of the surface and subsurface Svalbard annual snow Andrea Spolaor1,2, Elena Barbaro1,2, Jean Marc Christille3,4, Torben Kirchgeorg1, Fabio Giardi5, David Cappelletti6, Clara Turetta2, Andrea Bernagozzi3, Mats P. Björkman7, Enzo Bertolini3 and Carlo Barbante1,2 1Ca’ Foscari University of Venice, Department of Environmental Sciences, Informatics and Statistics, Santa Marta – Dorsoduro 2137, 30123 Venice, Italy – email: andrea.spolaor@unive.it 2Institute for the Dynamics of Environmental Processes, IDPA-CNR, Dorsoduro 2137, 30123 Venice, Italy. 3Research Unit Atlas, Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA), Loc. Lignan 39, 11020 Nus (AO), Italy. 4Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, I-06123 Perugia, Italy 5Chemistry Department – Analytical Chemistry, Scientific Pole, University of Florence, Via della Lastruccia 3, I-50019 Sesto Fiorentino (Florence) Italy. 6Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia I-06123 Perugia, Italy 7University of Gothenburg, Department of Earth Sciences, Box 460, 40530 Göteborg, Sweden Abstract Understanding and monitoring the evolution of annual snow is an important aspect of cryosphere research. Changes in physical proprieties such as hardness, presence of melt layers, or the shape and size of crystals can completely modify the robustness, propriety and quality of the snow. Evaluating these changes can inform the study and prediction of avalanches. The annual snow layer is an extremely dynamic portion of the cryosphere and can be defined as the snow accumulated on the ground during the year, from September to April. The characteristics of the annual snow strata can influence the access to food, particularly for animals that rely on food sources below the snow strata (Kohler et al. 2004). From a chemical point of view, snow depositions during the winter are a sink for an impressive amount of chemical compounds (natural and anthropogenic) and elements trapped in the snow layers. Particularly, compounds and elements that can be photo-activated accumulate during the winter and can be re-emitted in the atmosphere, taking part in numerous geochemical and biological cycles (Björkman et al. 2013) during the spring. However, elements that can be photo-activated are not the only ones to be released from the annual snow strata. During the melting phase, all elements and compounds that are still present in the snow can be released in the melting water (Bogdal et al. 2010), accumulate in the ground or be discharged in the sea, affecting biological productivity or, in the case of anthropogenic compounds, causing a spotted contamination of the surrounding environment. Two experiments were performed to evaluate the changes in the chemical composition of surface and subsurface annual snow. An in-depth investigation of the evolution of the first meter of the annual snow layer, with daily resolution, was conducted in the glacier of Austre Brøggerbreen, Svalbard, between the 27th of March and the 31st of May, in concomitance with the start of the melting phase (Spolaor et al. 2016). The present monitoring study mainly aimed to evaluate changes in the thermal profile and liquid water content (LWC) during the formation of a new ice layer (Figure 1) as well as the re-allocation of the total dissolved salts (TDS) and, more in detailed, the specific ionic compound as Na+, Br-, NO3 -,Cl-, Ca2+,Mg2+ ect. In addition, and to corroborate the previous experiment, three additionally experiments were performed, two at high temporal resolution between the 29th April and 1st of May 2015 (Figure 2) and between the 7th and the 10th of April 2016, and one sampling the surface snow (15 cm) with daily resolution between the 1st of April to the 30th of June 2014. The first high-resolution experiment were performed during the midnight sun season while the second ones when the