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Details van artikel 17 van 146 gevonden artikelen
| Titel: |
Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf |
| Auteur: |
L. M. Wehrmann N. J. Knab H. Pirlet V. Unnithan C. Wild T. G. Ferdelman |
| Verschenen in: |
Biogeosciences discussions |
| Paginering: | Jaargang 5 (2008) nr. 6 pagina's 4945-4992 |
| Jaar: |
2008 |
| Inhoud: |
Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.2 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmolS cm<sup>−3 d<sup>−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in –CH2O– groups and 43% carbon in –CH2– groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Iron reduction linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca<sup>2+, Mg<sup>2+ and Sr<sup>2+ concentrations in most cores and decreasing Ca<sup>2+ and Sr<sup>2+ concentrations with depth in core 23-18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments. |
| Uitgever: |
Copernicus GmbH (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 17 van 146 gevonden artikelen
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