Sediment accumulation rates and carbon burial in the bottom sediment in a high-productivity area: Gerlache Strait (Antarctica)

Abstract

Abstract Recent (100 yr) sediment, carbon, and nitrogen accumulation rates have been assessed at six different sites along a high-productivity area, Gerlache Strait, Antarctica. Organic carbon (OC) content in the sampled sediments along the Strait accounted for more than 90% of the total carbon, which ranged from 0.7% to 1.2% of the total mass (dry weight). Apparent mean sediment accumulation rates (SAR) varied between 630±30 and 1750±80 g m−2 yr−1 (0.65±0.03–3.11±0.14 mm yr−1). Bottom sediment from the eastern part of the Strait had the highest mean OC content and apparent mean SAR. The OC sedimentation rates were significant and fluctuated between 5 and 23 g m−2 yr−1. The highest values corresponded to the centre of the Strait. The eastern half of the Strait is the deposit area of both locally produced material and that generated farther to the west due to bottom topography together with hydrographical and biological controls. Between 71% and 83% of the OC originally deposited in the surface sediment remained below the surface mixed layer. The preservation ratio (remnant OC in the sediment column/primary production rates in the local euphotic zone) ranged from 1% to 6%. These ratios are comparable to other from Antarctic areas such as the Ross Sea. Nevertheless, the amount of primary-produced OC buried in the Gerlache Strait sediment is higher than in other areas such as the Bransfield Strait or the Ross Sea. The Gerlache Strait can be considered as a carbon-sink area, and it is able to export particulate OC to the adjacent western Bransfield Strait.