This project is 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 particulatew carbon deposition in the modern sediment is very low. The overall project is an integrated study of 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. The approach to be used to quantify the rates of bottom processes will be to collect box cores, piston cores, and kasten cores along specific transects in the Ross Sea that included both silica-rich and silica- poor sediments. Seabed dissolution of silica and degradation of organic carbon will be evaluated by measuring pore-water profiles of dissolved silica, carbon dioxide, amonia and nitrogen species, sulfates, and phosphates. Accumulation rates will be determined from radiochemical chronologies. These sea-floor studies will provide the closure for the surface production studies and the water column flux studies that will be carried out by other investigators cooperating in this project.
