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| Fontorbe, Guillaume; Frings, Patrick J.; De La Rocha, Christina L.; Hendry, Katharine R.; Conley, Daniel J.. |
| The Paleocene‐Eocene Thermal Maximum (PETM, ca. 56 Ma) is marked by a negative carbon isotope excursion (CIE) and increased global temperatures. The CIE is thought to result from the release of 13C‐depleted carbon, although the source(s) of carbon and triggers for its release, its rate of release, and the mechanisms by which the Earth system recovered are all debated. Many of the proposed mechanisms for the onset and recovery phases of the PETM make testable predictions about the marine silica cycle, making silicon isotope records a promising tool to address open questions about the PETM. We analyzed silicon isotope ratios (δ30Si) in radiolarian tests and sponge spicules from the Western North Atlantic (ODP Site 1051) across the PETM. Radiolarian δ30Si... |
| Tipo: Text |
Palavras-chave: Paleocene‐Eocene Thermal Maximum; Silicon biogeochemical cycle; Silicon isotopes; Weathering. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00627/73939/73287.pdf |
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| Sutton, Jill N.; Andre, Luc; Cardinal, Damien; Conley, Daniel J.; De Souza, Gregory F.; Dean, Jonathan; Dodd, Justin; Ehlert, Claudia; Ellwood, Michael J.; Frings, Patrick J.; Grasse, Patricia; Hendry, Katharine; Leng, Melanie J.; Michalopoulos, Panagiotis; Panizzo, Virginia N.; Swann, George E. A.. |
| Silicon (Si) is the second most abundant element in the Earth's crust and is an important nutrient in the ocean. The global Si cycle plays a critical role in regulating primary productivity and carbon cycling on the continents and in the oceans. Development of the analytical tools used to study the sources, sinks, and fluxes of the global Si cycle (e.g., elemental and stable isotope ratio data for Ge, Si, Zn, etc.) have recently led to major advances in our understanding of the mechanisms and processes that constrain the cycling of Si in the modern environment and in the past. Here, we provide background on the geochemical tools that are available for studying the Si cycle and highlight our current understanding of the marine, freshwater and terrestrial... |
| Tipo: Text |
Palavras-chave: C - N - O - Si isotopes; Biogenic silica; Element/Si ratios; Biogeochemical cycles; Silicon. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00431/54217/55547.pdf |
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| Barao, Lucia; Vandevenne, Floor; Clymans, Wim; Frings, Patrick; Ragueneau, Olivier; Meire, Patrick; Conley, Daniel J.; Struyf, Eric. |
| The biogeochemical cycling of silicon (Si) along the land-to-ocean continuum is studied by a variety of research fields and for a variety of scientific reasons. However, there is an increasing need to refine the methodology and the underlying assumptions used to determine biogenic silica (BSi) concentrations. Recent evidence suggests that contributions of nonbiogenic sources of Si dissolving during alkaline extractions, not corrected by standard silicate mineral dissolution correction protocols, can be substantial. The ratio between dissolved Si and aluminum (Al) monitored continuously during the alkaline extraction can be used to infer the origin of the Si fractions present. In this study, we applied both a continuous analysis method (0.5 M NaOH) and a... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00276/38725/73177.pdf |
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| Frings, Patrick J.; Clymans, Wim; Fontorbe, Guillaume; De La Rocha, Christina L.; Conley, Daniel J.. |
| The silicon isotope composition of biogenic silica (delta Si-30(BSi)) in the ocean is a function of the delta Si-30 of the available dissolved Si (DSi; H2SiO4), the degree of utilisation of the available DSi, and, for some organisms, the concentration of DSi. This makes delta Si-30(BSi) in sediment archives a promising proxy for past DSi concentrations and utilisation. At steady-state, mean delta Si-30(BSi) must equal a weighted average of the inputs, the majority of which are of continental origin. Variation in the functioning of the continental Si cycle on timescales similar to the residence time of DSi in the ocean (similar to 10 ka) may therefore contribute to downcore variability in delta Si-30(BSi) on millennial or longer time-scales. The direction... |
| Tipo: Text |
Palavras-chave: Global silicon cycle; Biogenic silica; Silicon isotopes; LGM; Palaeoceanography; Biogeochemical cycling. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53252/54714.pdf |
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| Nantke, Carla K. M.; Frings, Patrick J.; Stadmark, Johanna; Czymzik, Markus; Conley, Daniel J.. |
| Si fluxes from the continents to the ocean are a key element of the global Si cycle. Due to the ability of coastal ecosystems to process and retain Si, the ‘coastal filter’ has the potential to alter Si fluxes at a global scale. Coastal zones are diverse systems, sensitive to local environmental changes, where Si cycling is currently poorly understood. Here, we present the first palaeoenvironmental study of estuarine biogenic silica (BSi) fluxes and silicon isotope ratios in diatoms (δ30Sidiatom) using hand-picked diatom frustules in two sediment cores (CBdist and CBprox) from the Chesapeake Bay covering the last 12000 and 8000 years, respectively. Constrained by the well-understood Holocene evolution of the Chesapeake Bay, we interpret variations in Si... |
| Tipo: Text |
Palavras-chave: Diatoms; Estuarine sediments; Human impact; Si isotopes. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70083/68065.pdf |
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