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          Institute: MPI für marine Mikrobiologie     Collection: Abteilung Biogeochemie     Display Documents

ID: 13928.0, MPI für marine Mikrobiologie / Abteilung Biogeochemie
Modeling of subsurface calcite dissolution, including the respiration and reoxidation processes of marine sediments in the region of equatorial upwelling off Gabon
Authors:Pfeifer, K.; Hensen, C.; Adler, M.; Wenzhöfer, F.; Weber, B.; Schulz, H. D.
Date of Publication (YYYY-MM-DD):2002-12
Title of Journal:Geochimica et Cosmochimica Acta
Journal Abbrev.:Geochim. Cosmochim. Acta
Issue / Number:24
Start Page:4247
End Page:4259
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Mineralization of organic matter and the subsequent dissolution of calcite were simulated for surface sediments of the upper continental slope off Gabon by using microsensors to measure O- 2, pH, pCO(2) and Ca2+ (in situ), pore-water concentration profiles of NO3-, NH4+, Fe2+, and Mn2+ and SO42- (ex situ), as well as sulfate reduction rates derived from incubation experiments. The transport and reaction model CoTReM was used to simulate the degradation of organic matter by O-2, NO3-, Fe(OH)(3) and SO42-, reoxidation reactions involving Fe2+ and Mn2+, and precipitation of FeS. Model application revealed an overall rate of organic matter mineralization amounting to 50 mumol C cm(-2) yr(-1), of which 77% were due to O-2, 17% to NO3- and 3% to Fe(OH)(3) and 3% to SO42-. The best fit for the pH profile was achieved by adapting three different dissolution rate constants of calcite ranging between 0.01 and 0.5% d(-1) and accounting for different calcite phases in the sediment. A reaction order of 4.5 was assumed in the kinetic rate law. A CaCO3 flux to the sediment was estimated to occur at a rate of 42 g m(-2) yr(-1) in the area of equatorial upwelling. The model predicts a redissolution flux of calcite amounting to 36 g m(-2) yr(-1), thus indicating that similar to90% of the calcite flux to the sediment is redissolved. Copyright (C) 2002 Elsevier Science Ltd.
Comment of the Author/Creator:Date: 2002, DEC
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für marine Mikrobiologie
External Affiliations:Univ Bremen, Dept Geosci, POB 330 440, D-28334 Bremen, Germany; Univ Bremen, Dept Geosci, D-28334 Bremen, Germany; Max Planck Inst Marine Microbiol, D-28359 Bremen, Germany
Identifiers:ISI:000179837500004 [ID No:1]
ISSN:0016-7037 [ID No:2]
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