Downward particle fluxes and sediment accumulation rates in the western Bransfield Strait: Implications of lateral transport for carbon cycle studies in Antarctic marginal seas
Abstract:Downward particle and carbon fluxes were studied along with sediment and carbon accumulation fluxes in the western Bransfield Strait. Particle fluxes at 1000 m depth indicate that most of the carbon accumulated in the seabed at the study site is transported laterally. Biogenic components of the near-bottom particle fluxes included well-preserved organic matter with benthic diatoms, amphipoda and polychaetes that were resuspended and/or winnowed in shallow environments and transported basinward.
High near-bottom particle and carbon fluxes were in agreement with high sediment and carbon accumulation fluxes. About 12% of the near-bottom OC downward flux is buried below the SML in the deeper part of the basin. Carbon recycling in the sediment column is lower near the mouth of the Orleans Canyon (about 10%) than at the deeper part of the basin (about 50%). The carbon preserved in the sediment near the mouth of the canyon and at the deeper part of the basin represents about 9% and 3%, respectively, of the carbon produced in the euphotic layer of the study area. However, because most of the organic carbon (OC) is transported laterally, the higher primary productivity from nearby shallower areas should be considered and the percentage of the OC preserved in the sediment would account only for 4.5% and 1.5% at each of the study sites.
The results show that resuspension in shallow environments, lateral transport and near-bottom downward fluxes must be considered in addition to surface primary production, midwater downward fluxes and accumulation rates in order to better understand the carbon dynamics in Antarctic marginal seas. The accumulation rates at many sites of these seas appear to be more sensitive to variability in current-driven sediment redistribution than to changes in productivity, which must be taken into account when interpreting the paleoceanographic record.
Document Type: Research Article
Publication date: March 1, 2002
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