Large Aggregate Flux and Fate at the Seafloor: Diagenesis During the Rebound Process
Near-bottom sediment traps have been found to record higher fluxes of biogenic material than do traps in the mid-water column. The resuspension of biogenic-rich particles prior to their incorporation into the sediment, a process termed “rebound,” was inferred to be the cause (Walsh et aI., 1988a). Recent work with camera systems that quantitatively image aggregate (particles with diameters ≥0.5 mm) concentrations in the water column have established the presence of the benthic aggregate nepheloid layers implied by the rebound model (Gardner and Walsh, 1990; Walsh, 1990). The diagenetic effect of the rebound process is to increase the residence time of primary flux material above the sediment water interface. If the residence time of aggregates above the sediment water interface is 30 days, the diagenetic loss of the major biogenic components, assuming first-order decay at mid-water column rates, is approximately 20 to 60% of the organic carbon flux, 15 to 30% of the calcium carbonate flux and 10 to 40% of the biogenic opal flux.
KeywordsParticulate Organic Carbon Sediment Trap Sediment Water Interface Benthic Flux Particulate Organic Carbon Flux
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