Vertical budgets for organic carbon and biogenic silica in the Pacific sector of the Southern Ocean, 1996-1998

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Deep-Sea Research Part Ii-Topical Studies in Oceanography
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During the 1996-1998 Antarctic Environment and Southern Ocean Process Study (AESOPS), a component of US JGOFS, we obtained seasonal or longer-term data sets on the rates of production, vertical transport, remineralization and burial of particulate organic carbon (POC) and biogenic silica (BSiO2) in the Southern Ocean at 170degreesC between 55degreesS and 68degreesS. The AESOPS data records enable us to construct vertical C and Si budgets for the water column and upper sediments, with all estimates derived from direct measurement of the relevant fluxes. We constructed annual C and Si budgets for each of four ecologically distinct zonal bands within the system. For both POC and BSiO2 the greatest annual delivery to the sea floor (similar to200 and 1400 mmol m(-2) yr(-1), respectively) and burial (similar to6 and 160 mmol m(-2) yr(-1), respectively) were observed in the southern Antarctic Circumpolar Current (ACC) between 61.5degreesS and 65.5degreesS. That pattern is consistent with our observation that a diatom bloom propagated southward through the southern ACC during the spring and summer of 1997-1998, following the receding ice edge, and that this bloom was the main source of both POC and BSiO2 in the system on an annual basis. In the other zones the annual fluxes of POC and BSiO2 to the sea floor ranged from 19% to 67% of those in the zone traversed by the summer diatom bloom. The higher benthic fluxes of both POC and BSiO2 in the southern ACC imply that blooms similar to the one we observed in 1997-1998 occur commonly in the southern ACC, and that their high-productivity signature is transmitted to the sea floor.


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Pii S0967-0645(02)00005-X