Sediment accumulation rates and carbon fluxes to bottom sediments at the western Bransfield Strait (Antarctica)

Special issue: FRUELA - A Carbon Flux Study in the Antarctic Peninsula Area.-- 13 pages, 3 figures, 3 tablesMean sediment and carbon accumulation rates in the western Bransfield Strait, during the last ca. 100 years, were determined at three sites by using 210Pb as a radiotracer of sedimentation processes. 210Pb profiles showed moderate mixing in the upper 8.5-12 cm, which was attributed to bioturbation. Sediment accumulation rates calculated assuming no mixing below the surface mixed layer (SML) were found to be relatively high (between 0.03 and 0.09 gcm-2 yr-1), in good agreement with previously reported data based on both 210Pb and 14C dating in surrounding areas. These results, together with the calculated excess 210Pb fluxes to the bottom sediments and the 210Pb and 210Po distributions in the water column, indicated the presence of a large net advective flux of material in the area, highlighting the importance of glacial related sedimentation processes in this semi-enclosed sea. Carbon in bottom sediments was mainly organic, and its content was moderately low (0.65-1.25%), being slightly higher within the SML, reflecting the presence of inhabiting organisms. However, organic carbon (OC) accumulation fluxes (3.1-6.7 g Cm-2 yr-1) were considerable, due to the high sediment accumulation rates. 210Pb dated profiles allowed us to estimate the amount of carbon exported from the water column and buried in the bottom sediment, which represents about 3-7% of the mean annual primary production in the euphotic layer of the Bransfield Strait. The burial efficiency of OC in the sediment was estimated to be approximately 60-80%. © 2001 Published by Elsevier Science LtdThis research was funded by the Comisión Interministerial de Ciencia y Tecnologı́a of Spain, under contracts ANT94-1010, MAR96-1781-CO2-01 and ANT96-1346-E. It also benefited from a pre-doctoral fellowship from CONACYT (México), Reference 92766Peer Reviewe

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

13 pages, 4 figures, 3 tablesRecent (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. © 2002 Elsevier Science Ltd. All rights reservedThe Comisión Interministerial de Ciencia y Tecnologı́a of Spain funded this research under contracts ANT94-1010, MAR96-1781-CO2-01 and ANT96-1346-E. This sudy was also benefited with a pre-doctoral fellowship from CONACYT (México), reference 9276

Impact of bottom trawling on deep-sea surface sediments along the flanks of a mediterranean submarine canyon

3rd Annual Hermione Meeting, 11-14 September 2012, Faro, PortugalPeer Reviewe

210Pb as a tracer of sedimentary processes in the continental slope: the role of submarine canyon systems in the Western Mediterranean Sea

1 page, 1 figureThe natural radionuclide 210Pb is used here to assess the extent to which transfer of particles and sedimentation in continental margins is controlled by the presence of canyons. We studied three sites in the Western Mediterranean Sea, focusing on the evaluation of the global budgets of 210Pb and the temporal variability of the activity distributions in the water column and ?uxes derived from sediment traps and activity profiles in bottom sedimentsPeer reviewe