Capture Mechanisms of Mercury in Arctic Snow

Elemental concentrations in snow sampled from different periods in Longyearbyen and Ny-Ålesund, Svalbard, have been determined. Samples were taken to investigate the effect of atmospheric mercury deposition events on surface snow in Svalbard, and to look into capture mechanisms of mercury during and after AMDEs. Fieldwork for this thesis was carried out in March 2019, and several data sets from other periods were provided for comparison. The aim of this project has been to find evidence supporting theories on AMDEs, look into capture mechanisms of mercury by natural organic matter in surface snow, and to investigate sources of common elements and pollutants found in Svalbard snow. A highly varying amount of mercury was found in samples during the AMDE period, and the sampling days in Ny-Ålesund were found to be placed during depletion events by investigating a plot of GEM concentrations. Lower concentrations of mercury were found in snow sampled in other seasons. A principal component analysis revealed a clear seasonal variation in the elemental composition, whereas samples from March 2019 showed the most prominent deviation. A relatively low amount of organic matter was found in Svalbard snow, and SUVA values indicate the organic compounds found consist mainly of non-humic matter. No correlation was found between natural organic matter and mercury, which indicates that complexation of mercury with organics do not happen the way it does in aquatic systems such as effluent waters, or that the concentrations are too low for complexation to occur. A strong correlation found between mercury and chlorine and bromine could indicate mercury retention in snow by halogens. This could be a factor in the capture mechanisms of mercury in Svalbard snow.