Spatial variations of authigenic beryllium isotopes in surface sediments of the Antarctic oceans: a proxy for sea ice dynamics and sedimentary environments

Abstract

This study documents spatial variations in authigenic Be-9 and Be-10 concentrations and Be-10/Be-9 ratios in different glacial settings in the Weddell and Ross seas, Antarctica. Weddell Sea surface sediments have the lowest Be-10 and highest Be-9 concentrations, and most depleted Be-10/Be-9 ratios, as compared with other regions, indicating Be-9 enrichment from the recently collapsed Larsen Ice Shelf (LIS) B and reduction of Be-10 supply due to blockage by the un-deglaciated LIS C. Local Be-10 deposition varies across the open marine Ross Sea, which is more affected by seasonal sea ice persistence than ocean currents. Higher Be-10/Be-9 ratios in the western Ross Sea and higher Be-10 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 Be-10 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.