Modeling of subsurface calcite dissolution, including the respiration and reoxidation processes of marine sediments in the region of equatorial upwelling off Gabon

Pfeifer, Kerstin; Hensen, Christian; Adler, M.; Wenzhfer, F.; Weber, Bodo; Schulz, Horst D

doi:10.1016/s0016-7037(02)01073-6

Cited by 50 publications

(39 citation statements)

References 55 publications

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“…(16) can be used. Applicable for regional Si budget assessments of the oligo-and mesotrophic regions of the world ocean, the Si-O 2 coupling reported here complements a set of empirical relations provided by, e.g., Jahnke (1996) or Pfeifer et al (2002) which, in combination, can be used for the prediction of total diagenetic dissolution of biogenic particles, i.e., the non-lithogenic particle flux that basically consists of organic material, CaCO 3 , and BSi. Currently limited to sediments that are well-oxygenated and preserve opal, our findings may possibly be extrapolated to oxygen depleted oceanic environments.…”

Section: Discussionmentioning

confidence: 73%

“…A box volume is assigned to each node according to simple geometrical calculations, and the flux itself is approximated by finite differences. The model has been thoroughly tested and verified in a number of studies Wenzhöfer et al, 2001;Pfeifer et al, 2002;Hensen et al, 2003). The conceptual model consists of the oxidation of OM in welloxigenated milieus according to Froelich et al (1979) OM+138O 2 → 106CO 2 +16HNO 3 +122H 2 O+H 3 PO 4 (2) with OM having a Redfield composition of 106:16:1 (C:N:P) and silica dissolution…”

Section: Model Description and Setupmentioning

confidence: 99%

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Microbial mediation of benthic biogenic silica dissolution

Holstein

Hensen

2009

Geo-Mar Lett

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Pore water profiles from 24 stations in the South Atlantic (located in the Guinea, Angola, Cape, Guyana, and Argentine basins) show good correlations of oxygen and silicon, suggesting microbially mediated dissolution of biogenic silica. We used simple analytical transport and reaction models to show the tight coupling of the reconstructed process kinetics of aerobic respiration and silicon regeneration. A generic transport and reaction model successfully reproduced the majority of Si pore water profiles from aerobic respiration rates, confirming that the dissolution of biogenic silica (BSi) occurs proportionally to O 2 consumption. Possibly limited to well-oxygenated sediments poor in BSi, benthic Si fluxes can be inferred from O 2 uptake with satisfactory accuracy. Compared to aerobic respiration kinetics, the solubility of BSi emerged as a less influential parameter for silicon regeneration. Understanding the role of bacteria for silicon regeneration requires further investigations, some of which are outlined. The proposed aerobic respiration control of benthic silicon cycling is suitable for benthic-pelagic models. The empirical relation of BSi dissolution to aerobic respiration can be used for regionalization assessments and estimates of the silicon budget to increase the understanding of global primary and export production patterns.

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Section: Discussionmentioning

confidence: 73%

Section: Model Description and Setupmentioning

confidence: 99%

Microbial mediation of benthic biogenic silica dissolution

Holstein

Hensen

2009

Geo-Mar Lett

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“…The software has been described in great detail elsewhere (e.g. Adler et al, 2000Adler et al, , 2001Wenzhöfer et al, 2001;Pfeifer et al, 2002). Notably, CoTReM has already been successfully applied to model transport processes and geochemical reactions at two mud volcanoes of the Eastern Mediterranean (Haese et al, 2003(Haese et al, , 2006.…”

Section: Geochemical Modeling With "Cotrem"mentioning

confidence: 99%

Interaction between hydrocarbon seepage, chemosynthetic communities, and bottom water redox at cold seeps of the Makran accretionary prism: insights from habitat-specific pore water sampling and modeling

et al. 2012

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Abstract. The interaction between fluid seepage, bottom water redox, and chemosynthetic communities was studied at cold seeps across one of the world's largest oxygen minimum zones (OMZ) located at the Makran convergent continental margin. Push cores were obtained from seeps within and below the core-OMZ with a remotely operated vehicle. Extracted sediment pore water was analyzed for sulfide and sulfate concentrations. Depending on oxygen availability in the bottom water, seeps were either colonized by microbial mats or by mats and macrofauna. The latter, including ampharetid polychaetes and vesicomyid clams, occurred in distinct benthic habitats, which were arranged in a concentric fashion around gas orifices. At most sites colonized by microbial mats, hydrogen sulfide was exported into the bottom water. Where macrofauna was widely abundant, hydrogen sulfide was retained within the sediment.Numerical modeling of pore water profiles was performed in order to assess rates of fluid advection and bioirrigation. While the magnitude of upward fluid flow decreased from 11 cm yr −1 to <1 cm yr −1 and the sulfate/methane transition (SMT) deepened with increasing distance from the central gas orifice, the fluxes of sulfate into the SMT did not significantly differ (6.6-9.3 mol m −2 yr −1 ). Depth-integrated rates of bioirrigation increased from 120 cm yr −1 in the central habitat, characterized by microbial mats and sparse macrofauna, to 297 cm yr −1 in the habitat of large and few small vesicomyid clams. These results reveal that chemosynthetic macrofauna inhabiting the outer seep habitats below the core-OMZ efficiently bioirrigate and thus transport sulfate down into the upper 10 to 15 cm of the sediment. In this way the animals deal with the lower upward flux of methane in outer habitats by stimulating rates of anaerobic oxidation of methane (AOM) with sulfate high enough to provide hydrogen sulfide for chemosynthesis. Through bioirrigation, macrofauna engineer their geochemical environment and fuel upward sulfide flux via AOM. Furthermore, due to the introduction of oxygenated bottom water into the sediment via bioirrigation, the depth of the sulfide sink gradually deepens towards outer habitats. We therefore suggest thatin addition to the oxygen levels in the water column, which determine whether macrofaunal communities can develop or not -it is the depth of the SMT and thus of sulfide production that determines which chemosynthetic communities are able to exploit the sulfide at depth. We hypothesize that large vesicomyid clams, by efficiently expanding the sulfate zone down into the sediment, could cut off smaller or less mobile organisms, as e.g. small clams and sulfur bacteria, from the sulfide source.

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“…Various studies suggest aerobic organic matter degradation as the most likely cause for calcite dissolution in supralysoclinal sediments as well as sediments located below high-productivity regions (e.g., Reichart et al, 1997;Pfeifer et al, 2002;Volbers and Henrich, 2002;de Villiers, 2005). A regression analysis of TOC versus carbonate suggests that a linear model does not fit well (R 2 ¼ 0.41 and p-Value 95%confid .…”

Section: Dissolutionmentioning

confidence: 99%

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Plewa

Meggers

Kuhlmann

et al. 2012

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tOne hundred and twenty-eight surface-sediment samples collected off North-West Africa were studied geochemically to detect the expressions of different meridional climate regimes and zonal productivity gradients in the surface sediments. This geochemical multi-tracer approach, coupled with additional information on the bulk carbonate and TOC contents makes it possible to characterise the sedimentological regime in detail. Typical terrigenous elements like Al, K and Fe mirror the importance of the humid (fluvial) influence in the north of the study area and the dominance of aeolian input in the south. Furthermore, the distributions of Ti and Fe in the surface sediments serve as tracers for the supply of eolian volcanic material from the Canary Islands. The spatial variability of the TOC contents in the surface sediments closely follows the ocean surface productivity patterns, whereas the CaCO 3 contents are mainly controlled by dilution with terrigenous matter. The potential productivity proxy Ba is not a reliable tracer for productivity in this region, since it is mainly supplied by terrigenous input (coupled with aluminosilicates).

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Modeling of subsurface calcite dissolution, including the respiration and reoxidation processes of marine sediments in the region of equatorial upwelling off Gabon

Cited by 50 publications

References 55 publications

Microbial mediation of benthic biogenic silica dissolution

Microbial mediation of benthic biogenic silica dissolution

Interaction between hydrocarbon seepage, chemosynthetic communities, and bottom water redox at cold seeps of the Makran accretionary prism: insights from habitat-specific pore water sampling and modeling

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

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