Halogens and Biological component in Spitsbergen snow: understanding the role of sea ice.

The halogens atmospheric chemistry has received increased attention in the last twenty years since they’re directly involved in the ozone reactions. Bromine has in the ocean the main reservoir and the sea spray aerosol is considered the main driver for its concentration in the snow. However, additional source could become predominant and enriching bromine in the deposition. One additional source is represented by bromine explosion that can occur above the first year sea ice. The emission of gas phase bromine can enriched this element compared to the seawater abundance. Iodine in the polar region is associated with the biological productivity and the increase of primary production could lead to an increase of iodine emission. Studies suggest that the retreat of sea ice could increase the primary production and associated iodine emission into the atmosphere. Considering that both elements seem presenting a direct link with the sea ice dynamic we drill two shallow cores with the aim to study the linkage between iodine and bromine and sea ice. In 2012, a first shallow core has been drilled at the top of the Holtedhalfonna (79° 09’N, 13° 23’ E, at an altitude of 1150 m a.s.l.), while in 2013 a second core has been drilled in the Staxrudfaonna (79°50’N, 11°45’E, at an altitude of 920 m.a.s.l.). The first drilling site was in average located 100 km from the sea ice edge, while the second is located closer, approximately 40 km. Iodine (I) and bromine (Br) measurements in the first cores suggest that changing I concentrations can be linked to the retreat of spring sea ice extension while bromine enrichment, indexed to the Br/Na seawater mass ratio, appears to be influenced by changes in the seasonal sea ice extension. We present the first comparison between halogens in surface snow and Arctic sea ice extension, especially from the region closer to Svalbard Archipelago. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the March-May sea ice extension and seasonal sea ice surface area. Considering the likely role of the biological production controlling the iodine emission and the suggested relationship between primary production and sea ice extension we develop a preliminary study investigating the biological component in the snow. In particular,pigment specta, morphological and molecular analyses have been performed on the sea ice (snow???) to characterize the microalgal communities. Proposed Topic: Ice core chemistry, Paleoclimate, atmospheric chemistry molecular ecology, microalgae taxonom