Consulta: subjectFacets:"Early diagenesis"
Registros recuperados: 9
Data/hora: 09/06/2024 06:42:32

Effects of seasonal dynamics in a Zostera noltii meadow on phosphorus and iron cycles in a tidal mudflat (Arcachon Bay, France)
Provedor de dados: 5
Autores: Deborde, Jonathan; Abrill, Gwenael; Mouret, Aurelia; Jezequel, Didier; Thouzeau, Gerard; Clavier, Jacques; Bachelet, Guy; Anschutz, Pierre.
A study was conducted in Arcachon Bay, France, to determine the effect of seasonal dynamics in a Zostera noltii meadow on P and Fe cycles in the superficial sediments of a tidal mudflat. The redox-sensitive Fe particulate pool and associated P in the root zone showed a seasonal variation following the growth and decay of Z. noltii biomass, with a maximum content during the growth period. In comparison, the bare sediments did not show significant seasonal changes. A dissolved inorganic phosphorus (DIP) uptake was measured from the water column to the sediment in vegetated sediments, whereas a net DIP efflux was observed in the unvegetated sediments. During the growth period, the formation of an iron oxihydroxide-rich zone occurred and acted as a trap for...
Tipo: Text
Palavras-chave: Nutrient; Eelgrass growth; Intertidal zone; Lagoon; Early diagenesis.
Ano: 2008
URL: https://archimer.ifremer.fr/doc/00603/71539/69966.pdf

Influence of early diagenesis on geotechnical properties of clay sediments (Romania, Black Sea)
Provedor de dados: 5
Autores: Ballas, Gregory; Garziglia, Sebastien; Sultan, Nabil; Pelleter, Ewan; Toucanne, Samuel; Marsset, Tania; Riboulot, Vincent; Ker, Stephan.
The geotechnical properties of clay sediments were investigated using laboratory and in-situ measurements as part of the geohazard assessment in the Romanian sector of the Black Sea affected by landslides and seafloor deformation features. The sediments were characterized as predominantly high plastic silty clay of high compressibility, low undrained shear strength, low cohesion and moderate sensitivity. A shallow increase in shear strength exceeding the general trend could have been reconciled with evidence for the precipitation of iron sulfides and calcium carbonates related to early diagenetic reactions of sulfate reduction (e.g. cryptic sulfur cycle) and anaerobic oxidation of methane. Comparison of the compression behaviour of natural and...
Tipo: Text
Palavras-chave: Lacustrine clay sediment; Structured material; Sulfur cement; Carbonate cement; Early diagenesis; Weak layer.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00439/55064/56545.pdf

Diagenetic production, accumulation and sediment-water exchanges of methylmercury in contrasted sediment facies of Lake Titicaca (Bolivia)
Provedor de dados: 5
Autores: Guédron, S.; Audry, S.; Acha, D.; Bouchet, S.; Point, D.; Condom, T.; Heredia, C.; Campillo, S.; Baya, A.; Groleau, A.; Amice, Erwan; Amouroux, D.
Monomethylmercury (MMHg) concentrations in aquatic biota from Lake Titicaca are elevated although the mercury (Hg) contamination level of the lake is low. The contribution of sediments to the lake MMHg pool remained however unclear. In this work, seven cores representative of the contrasted sediments and aquatic ecotopes of Lake Titicaca were sliced and analyzed for Hg and redox-sensitive elements (Mn, Fe, N and S) speciation in pore-water (PW) and sediment to document early diagenetic processes responsible for MMHg production and accumulation in PW during organic matter (OM) oxidation. The highest MMHg concentrations (up to 12.2 ng L−1 and 90% of THg) were found in subsurface PWs of the carbonate-rich sediments which cover 75% of the small basin and 20%...
Tipo: Text
Palavras-chave: Methylmercury; Lake sediment; Early diagenesis; High altitude ecosystem; Diffusive fluxes.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00615/72735/71843.pdf

Strong gradient of benthic biogeochemical processes along a macrotidal temperate estuary: focus on P and Si cycles
Provedor de dados: 5
Autores: Raimonet, Melanie; Andrieux, Francoise; Ragueneau, Olivier; Michaud, Emma; Kerouel, Roger; Philippon, Xavier; Nonent, Michel; Memery, Laurent.
Tipo: Text
Palavras-chave: Early diagenesis; Silicate; Phosphate; Authigenic phosphorus; Macrotidal; Estuary.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00130/24115/22493.pdf

Le système des carbonates influencé par la diagenèse précoce dans les sédiments côtiers méditerranéens en lien avec l’acidification des océans
Provedor de dados: 5
Autores: Rassmann, Jens.
Continental shelves are key regions for the global carbon cycle and particularly exposed to ocean acidification. A large part of organic matter (OM) of continental and marine origin is mineralized in estuarine sediments following oxic and anoxic pathways. This mineralization produces dissolved inorganic carbon (DIC) leading to acidification of the bottom waters. Anoxic mineralization can produce total alkalinity (TA) that can contribute to buffer bottom water pH and increase the CO2 storage capacity of seawater. Measurements in the sediments of the Rhone River prodelta showed that anoxic mineralization, especially sulfate reduction, are the major pathways of OM mineralization and create high DIC and TA fluxes. Land derived OM is mineralized close to the...
Tipo: Text
Palavras-chave: Carbonate system; Early diagenesis; Mineralization; Pelagic-bentic fluxes; Rhone prodelta; Ocean acidification.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00659/77076/78398.pdf

Organic Carbon Origin, Benthic Faunal Consumption, and Burial in Sediments of Northern Atlantic and Arctic Fjords (60–81°N)
Provedor de dados: 5
Autores: Włodarska‐kowalczuk, Maria; Mazurkiewicz, Mikołaj; Górska, Barbara; Michel, Loic; Jankowska, Emilia; Zaborska, Agata.
Fjords have been recently recognized as hotspots of organic carbon (Corg) sequestration in marine sediments. This study aims to identify regional and local drivers of variability of Corg burial in north Atlantic and Arctic fjords. We provide a comparative quantification of Corg, δ13C, photosynthetic pigments content, benthic biomass, consumption, Corg accumulation and burial rates in sediments in six fjords (60 to 810N). Higher sediment Corg content in southern Norway reflected longer phytoplankton growth season and higher productivity. Higher contributions of terrestrial Corg were noted in temperate/southern Norway (dense land vegetation and high precipitation) and Arctic/Svalbard (glacial erosion) than in subarctic/northern Norway locations. Benthic...
Tipo: Text
Palavras-chave: S; Organic matter preservation; Organic carbon sequestration; Benthic carbon mineralization; Sedimentary processes; Early diagenesis; Marine geochemistry.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00591/70318/68353.pdf

Comportement du cadmium et du mercure lors de la diagenèse précoce et flux à l'interface eau-sédiments en zone littorale
Provedor de dados: 5
Autores: Gonzalez, Jean-louis.
The early diagenesis of Cd and Hg has been studied in different coastal areas (vasière Ouest-Gironde, Pertuis d'Antioche, baie de Marennes-Oléron). For these two metals, the fluxes at the sediment-water interface have been calculated. Considering only molecular diffusion, the diffusionnal fluxes of Cd and Hg to the colurnn water are negligible with regard to both the particular fluxes to the sediments and the inputs of the "Gironde" and "Charente" ·,estuaries. The take into account of the different processes which affect the ex changes at the interface (erosion, bioturbation) permits more realistic an estimation of the role of sediments in the geochemical cycle of Cd and Hg. The results show that up to 50% of particular Cd and Hg which are integrated into...
Tipo: Text
Palavras-chave: Cadmium; Mercure; Eaux intrstitielles; Diagenèse précoce; Flux; Interface eaux-sédiments; Bioturbation; Modélisation; Cadmium; Mercury; Pore waters; Early diagenesis; Fluxes; Sediment-water interface; Bioturbation; Modelling.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/00442/55402/56920.pdf

Characteristics, distribution and diagenetic stages of chert in the La Silla Formation (Lower Ordovician), Argentine Precordillera
Provedor de dados: 42
Autores: Raviolo,Mariana M.; Barbosa,José A.; Neumann,Virgínio H.
The late Cambrian - late Tremadocian La Silla Formation is a carbonate unit of the eastern Precordillera in Argentina whose facies indicate a shallow platform environment. Until this moment, there were no studies that referred to the diagenetic evolution of these rocks. The present study involves the characteristics and distribution of the silicification that affects this unit and determines its different diagenetic stages through petrographic (with cathodoluminescence support) and stratigraphic analyses. An early diagenetic chert, in a stage previous to the compactation, was observed. This chert is related to silica-rich seawater in contact with permeable and porous sediments. A later pulse of chert, associated with fracturing, also occurs. The knowledge...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carbonates; Chert; Early diagenesis; Eastern Precordillera; Lower Ordovician.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000400015

Carbonate cements in contemporaneous beachrocks, Jaguaribe beach, Itamaracá island, northeastern Brazil: petrographic, geochemical and isotopic aspects
Provedor de dados: 42
Autores: Guerra,Núbia C.; Kiang,Chang H.; Sial,Alcides N.
Holocene beachrocks of the Jaguaribe beach, State of Pernambuco, northeastern Brazil, consist of horizontal, cemented layers approximately 40 cm thick. The cement shows three textural varieties: (a) calciferous, surrounding siliciclastic grains, (b) micritic, with an acicular fringe; and (c) cryptocrystalline calcite in pores. Early cementation took place at the water table below beach ridges, where geochemical, hydrodynamic and, perhaps, also microbiological conditions favored rapid precipitation of aragonite and/or high-Mg calcite. delta13C values range from -1.8 to +1.5‰ for dissolved carbonate in interstitial water and from +0.2 to +2.1‰ for bioclastic components. delta18O values range from -2.8 to +0.5‰ for seawater, freshwater and interstitial water....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Beachrocks; Early diagenesis; O and C isotopes; Holocene.
Ano: 2005
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652005000200011