Mercury concentrations of snow samples from the McMurdo Ice Shelf and the Antarctic plateau

Analysis of mercury concentrations from snow samples from Antarctica should indicate global fluxes of mercury to the atmosphere, since it is a remote location away from any regional mercury sources. Furthermore, it may be possible to determine the human contribution to the total atmospheric mercury flux by comparing the mercury content of recent and pre-industrial snow. Snow samples were taken from two sites over two seasons and analysed for mercury content. The first season's site was 16 km east of Williams Air Field runway on the McMurdo Ice Shelf. Surface and pit samples were melted, then SnCl2 was added (a reducing agent) and the sample was bubbled with purified N2 gas to release the mercury into a gold coated sand trap. Each gold trap had its mercury content analysed by a photoacoustic mercury analyser. Samples were weighed before being discarded. The second season's site was located on the Antarctic plateau, in the Quartermain Mountains. Surface and pit samples were analysed with the same method in the first season. Samples of snow from 2 cm wide strips were taken at approximately 5 cm intervals over three sets of layers and analysed for the deuterim content of the ice in order to determine if each layer represents an annual deposit. Snow samples were also collected from each layer for chemical analysis for major components (e.g. chloride, sulphate, sodium, calcium).