Spatial Variations of Authigenic Beryllium Isotopes in Surface Sediments of the Antarctic Oceans: a Proxy for Sea Ice Dynamics and Sedimentary Environments

This study documents spatial variations in authigenic 9Be and 10Be concentrations and 10Be/9Be ratios in different glacial settings in the Weddell and Ross seas, Antarctica. Weddell Sea surface sediments have the lowest 10Be and highest 9Be concentrations, and most depleted 10Be/9Be ratios, as compared with other regions, indicating 9Be enrichment from the recently collapsed Larsen Ice Shelf (LIS) B and reduction of 10Be supply due to blockage by the un-deglaciated LIS C. Local 10Be deposition varies across the open marine Ross Sea, which is more affected by seasonal sea ice persistence than ocean currents. Higher 10Be/9Be ratios in the western Ross Sea and higher 10Be concentrations in the eastern Ross Sea correlate with higher sea ice concentrations and changes, and vice versa in the central Ross Sea. The higher sea ice concentration not only blocks atmospheric 10Be and dust deposition during the frozen season, but increases the dust flux and supply of Be isotopes during the sea ice melting season. Thus, the spatial distribution of Be isotopes in surface sediments of the Antarctic oceans can be used as a proxy for sea ice dynamics and sedimentary environments.