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Early diagenesis and sediment-water exchange in the Savu Basin (eastern Indonesia)
Helder, W. (1989). Early diagenesis and sediment-water exchange in the Savu Basin (eastern Indonesia). Neth. J. Sea Res. 24(4): 555-572
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
Peer reviewed article  

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Keyword
    Marine

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  • Helder, W.

Abstract
    The Savu Basin (max. depth 3400 m) was visited during the Snellius-II Expedition in March 1985 and May 1985. The watercolumn and the sediments were sampled at twelve stations. 02 profiles were measured in subcores with microelectrodes, and the pore waters were analysed for NO3-, NO2-, NH4+, dissolved Si, dissolved Mn, and dissolved Fe. The sediment was analysed for organic C, organic N, and for Mn- and Fe-oxides. The maximum penetration of 02 into sediment was restricted to 1.3 cm. Fluxes calculated from pore-water gradients showed that 02 is responsible for about 60% of the total organic C oxidation, N03- for about 25%, and Mn-oxide and S042- reduction accounted each for about 7%. This contrasts with a station in the nearby Indian Ocean. With a 2.5 fold lower sediment accumulation rate, the contribution of 02 to organic C oxidation in the sediment was 86%, and NO3- reduction accounted for 13%. Pore-water profiles of dissolved Si showed large increases from the sediment-water interface to 1.5 cm depth. Below this depth, concentrations stabilized, reaching values of 550-850 µM at different stations. The diffusive flux of dissolved Si creates an excess of dissolved Si in the overlying water. From the total integrated excess of dissolved Si in the water below the sill depth of the basin and the diffusive flux of dissolved Si from the sediment, a transit time of 7 to 13 years for this water mass was estimated.

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