210Pb Accumulation Rates in Andvord Bay, Western Antarctic Peninsula

Abstract

With the rate of temperature rise on the Western Antarctic Peninsula (WAP) being six times higher than the global average, the effects of modern climate change on glacier dynamics and meltwater production hold particular significance for sediment accumulation rates. Few data exist for examining the subbasin variability of sediment accumulation in an individual fjord, where only 1-2 cores per fjord are available. In Andvord Bay, Antarctica, modern sediment accumulation rates were determined from 9 kasten cores collected throughout the fjord aboard the R/V Nathaniel B. Palmer. A relatively low circulation velocity, and numerous deep basins throughout the fjord created ideal conditions for sediment to accumulate, and to be easily cored. Sediment accumulation rates were determined using 210Pb geochronology, where excess 210Pb activity profiles reveal spatially variable steady-state sediment accumulation rates throughout the fjord that are on the order of millimeters of accumulation per year. These modern accumulation rates agree with previously determined accumulation rates in polar and subpolar fjords, and are significantly slower than those of temperate tidewater glaciers, further indicating that the subpolar fjords of the WAP have been accumulating sediment at a steady-state for the past century. These excess 210Pb activity profiles provide further insight into the small-scale spatial variability of sediment transport and accumulation in individual fjords, and contribute to the subpolar-polar sediment accumulation dataset that is imperative for understanding the effects of modern climate change on the dynamics of glaciers at high latitudes.