The Preservation and Accumulation of Biogenic Silica and Organic Carbon in an High-Latitude Environment: The Ross Sea

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This project is the renewal of a study of the rates of deposition, seabed regeneration, and sediment accumulation of biogenic silica and organic carbon in the Ross Sea, and is part of a coordinated study of the biogenic silica and organic carbon cycling in the water column and the sediments of the Ross Sea. The antarctic deep sea and continental shelf environment is the major repository for silica accumulation in the global ocean, and dominates the global silica budget. The Ross Sea is a particularly anomalous area in which large amounts of biogenic silica are accumulating in modern sediments, while the surface production rates are generally below the global average. Moreover the usual similarity between the oceanic silicon and carbon cycle does not appear to hold around Antarctica, and the two cycles are decoupled in that the rate of particulate carbon deposition in the modern sediment is very low. The overall project is an integrated study of the production, vertical transport, dissolution, and deposition processes, using moored instrumentation and direct observations in a series of transects in the Ross Sea by R/V POLAR DUKE, carried out between 1989 and 1991. In this project, box cores, piston cores, and kasten cores were collected along specific transects in the Ross Sea that included both silica-rich and silica-poor sediments. Based on carbon-14 chronologies and seabed analyses of biogenic silica and organic carbon content, three sites with accumulation rates differing by several orders of magnitude have been identified. At these sites large differences in seabed preservation efficiency exist for both biogenic silica and organic carbon. This renewed effort will be concerned with further analysis of data from the two cruises, including seabed regeneration rates, carbon-14 sediment chronologies, and horizontal transportation rates for biogenic material in the water column, and to integrate these results with production and vertical transport studies being completed by other cooperating investigators.