2024-03-29T00:07:06Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/177112009-10-15T22:00:00Zcom_10261_132com_10261_8col_10261_385
00925njm 22002777a 4500
dc
Ragueneau, O.
author
Regaudie de Gioux, Aurore
author
Moriceau, B.
author
Gallinari, M.
author
Vangriesheim, A.
author
Baurand, F.
author
Khripounoff, A.
author
2009-04-14
To elucidate the origin of the silicic acid (DSi) anomaly observed along the 4000 isobath on the Congo margin, we have established a benthic Si mass balance and performed direct measurements of biogenic silica (bSiO2) dissolution in the deep waters and in the sediments. Results strongly suggest that the anomaly originates from the sediments; the intensity of DSi recycling is consistent with the degradation of organic matter, as observed from Si:O2 ratios in the benthic fluxes compared to that ratio observed in the anomalies. Strong imbalances, observed in both the Si and C mass balances, suggest that the biogenic matter that degrades and dissolves in these sediments near 4000 m does not come from pelagic sedimentation. It is probably not coming also from the deep channel, because observations were similar in the deep channel vicinity (site D) and further south, far from its influence (site C). The composition of the sediments, with an Si:C ratio close to that observed on continental shelves, suggests that this matter is coming from downslope transport. A first estimate of the magnitude of this flux at global scale, close to 12 T mol Si yr−1, suggests that it may be an important path for transferring Si from land to ocean.
Deep Sea Research Part II: Topical Studies in Oceanography (2009), doi: 10.1016/j.dsr2.2009.04.003 (In press)
0967-0645
http://hdl.handle.net/10261/17711
10.1016/j.dsr2.2009.04.003
Biogenic silica
Dissolution
Preservation
Continental margin
Congo
A benthic Si mass balance on the Congo margin: Origin of the 4000 m DSi anomaly and implications for the transfer of Si from land to ocean