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  • 1
    Publikationsdatum: 2023-01-21
    Beschreibung: Fossil‐bound organic material holds great potential for the reconstruction of past changes in nitrogen (N) cycling. Here, with a series of laboratory experiments, we assess the potential effect of oxidative degradation, fossil dissolution, and thermal alteration on the fossil‐bound N isotopic composition of different fossil types, including deep and shallow water scleractinian corals, foraminifera, diatoms and tooth enamel. Our experiments show that exposure to different oxidizing reagents does not significantly affect the N isotopic composition or N content of any of the fossil types analyzed, demonstrating that organic matter is well protected from changes in the surrounding environment by the mineral matrix. In addition, we show that partial dissolution (of up to 70%–90%) of fossil aragonite, calcite, opal, or enamel matrixes has a negligible effect on the N isotopic composition and N content of the fossils. These results suggest that the isotopic composition of fossil‐bound organic material is relatively uniform, and also that N exposed during dissolution is lost without significant isotopic discrimination. Finally, our heating experiments show negligible changes in the N isotopic composition and N content of all fossil types at 100°C. At 200°C and hotter, any N loss and associated nitrogen isotope changes appear to be directly linked to the sensitivity of the mineral matrix to thermal stress, which depends on the biomineral type. These results suggest that, so long as high temperature does not compromise the mineral structure, the biomineral matrix acts as a closed system with respect to N, and the N isotopic composition of the fossil remains unchanged.
    Beschreibung: Plain Language Summary: The ratio of the heavy and light isotopes of nitrogen (15N and 14N) in the organic material contained within the mineral structure of fossils can be used to reconstruct past changes in biological and chemical processes. With a series of laboratory experiments, we evaluate the potential effects of chemical conditions, fossil dissolution, and heating on the nitrogen isotopic composition (15N/14N ratio) of corals, foraminifera, diatoms and tooth enamel. Our results indicate that these processes do not have a significant effect on the 15N/14N of fossils, suggesting that the mineral matrix provides a barrier that isolates a fossil's organic nitrogen from the surrounding environment, preventing alteration of its 15N/14N. In addition, we show that if part of the fossil‐bound organic nitrogen is exposed by dissolution or heating, it is lost without affecting the 15N/14N of the organic material that remains in the mineral. These findings imply that the original 15N/14N ratio incorporated by the organism is preserved in the geologic record. Therefore, measurements of the nitrogen isotopes on fossils can provide faithful biological, ecological, and environmental information about the past.
    Beschreibung: Key Points: Fossil‐bound organic matter is well protected by the mineral matrix from chemical changes in the surrounding environment. Partial dissolution of fossil calcite, aragonite, opal, and enamel has a negligible effect on their N isotopic composition and N content. During heating, fossil N content and isotopic composition remains unchanged if the structure of the inorganic matrix is not compromised.
    Beschreibung: Max Planck Society
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: US National Science Foundation
    Beschreibung: Paul Crutzen Nobel Prize Fellowship
    Beschreibung: https://doi.org/10.5281/zenodo.6884681
    Schlagwort(e): ddc:551.9 ; nitrogen isotopes ; diagenesis ; foraminifera ; corals ; diatoms ; teeth
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2020-06-26
    Beschreibung: Highlights: • GEOTRACES releases its first integrated and quality controlled Intermediate Data Product 2014 (IDP2014). • The IDP2014 digital data are available at http://www.bodc.ac.uk/geotraces/data/idp2014/ in 4 different formats. • The eGEOTRACES Electronic Atlas at http://egeotraces.org/ provides 329 section plots and 90 animated 3D tracer scenes. • The new 3D scenes provide geographical and bathymetric context crucial for tracer assessment and interpretation. Abstract: The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as classical hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing a strongly inter-linked on-line atlas including more than 300 section plots and 90 animated 3D scenes. The IDP2014 covers the Atlantic, Arctic, and Indian oceans, exhibiting highest data density in the Atlantic. The TEI data in the IDP2014 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at cross-over stations. The digital data are provided in several formats, including ASCII spreadsheet, Excel spreadsheet, netCDF, and Ocean Data View collection. In addition to the actual data values the IDP2014 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering. Metadata about data originators, analytical methods and original publications related to the data are linked to the data in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2014 data providing section plots and a new kind of animated 3D scenes. The basin-wide 3D scenes allow for viewing of data from many cruises at the same time, thereby providing quick overviews of large-scale tracer distributions. In addition, the 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of observed tracer plumes, as well as for making inferences about controlling processes.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2021-02-08
    Beschreibung: The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 22 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2021-02-08
    Beschreibung: Despite slow nutrient supply to the subtropical surface ocean, its rates of annual inorganic carbon drawdown and net oxygen production are similar to those of nutrient-rich high latitude waters. This surprisingly rapid carbon drawdown, if due to the production and export of marine biomass, cannot be explained in terms of known nutrient supply mechanisms. Moreover, carbon budgets have failed to detect the export of this organic matter. One possible explanation is the export of nutrient-poor organic matter with a composition that avoids detection as sinking particles. We describe three signs of the decomposition of such organic matter in the shallow Sargasso Sea subsurface. First, summertime oxygen consumption at 80–400 m occurs without the rate of nitrate and phosphate production expected from the remineralization of marine biomass, matching the observed summertime mixed layer inorganic carbon drawdown. Second, a seasonal change in the 18O/16O of subsurface nitrate suggests summertime heterotrophic bacterial nitrate assimilation down to ~400 m, as may be required for the remineralization of nutrient-poor organic matter. Third, incubation of subsurface seawater leads to nitrate drawdown and heterotrophic bacterial growth, supporting the thermocline nitrate 18O/16O evidence for heterotrophic nitrate assimilation. These three pieces of evidence suggest the export of nutrient-poor organic matter from the surface at a rate adequate to explain net community production in the Sargasso Sea. We propose that transparent exopolymer particles or related compounds, generated by a nutrient-limited upper ocean ecosystem, comprise this nutrient-poor export, and that its properties cause its flux out of the euphotic zone to be underestimated by sediment traps. Such nutrient-poor organic matter would contribute little to fisheries, deep ocean carbon dioxide storage, or organic carbon burial, so that it may change our view of the significance of net community production in the subtropical ocean
    Materialart: Article , PeerReviewed
    Format: text
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    facet.materialart.
    Unbekannt
    PANGAEA
    In:  Supplement to: Pride, Carol; Thunell, Robert C; Sigman, Daniel M; Keigwin, Lloyd D; Altabet, Mark A; Tappa, Eric (1999): Nitrogen isotopic variations in the Gulf of California since the Last Deglaciation: Response to global climate change. Paleoceanography, 14(3), 397-409, https://doi.org/10.1029/1999PA900004
    Publikationsdatum: 2023-05-12
    Beschreibung: High-resolution records of the nitrogen isotopic composition of organic matter (d15Norg), opal content, and opal accumulation rates from the central Gulf of California reveal large and abrupt variations during deglaciation and gradual Holocene changes coincident with climatic changes recorded in the North Atlantic. Homogenous sediments with relatively low d15Norg values and low opal content were deposited at the end of the last glacial period, during the Younger-Dryas event, and during the middle to late Holocene. In contrast, laminated sediments deposited in the two deglacial stages are characterized by very high d15Norg values (〉14 per mil) and opal accumulation rates (29-41 mg/cm**2/yr). Abrupt shifts in d15Norg were driven by widespread changes in the extent of suboxic subsurface waters supporting denitrification and were amplified in the central gulf record due to variations in upwelling, vertical mixing, and/or the latitudinal position of the Intertropical Convergence Zone.
    Materialart: Dataset
    Format: application/zip, 5 datasets
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2023-06-27
    Schlagwort(e): DEPTH, sediment/rock; GGC; GGC-55; Giant gravity corer; Opal, biogenic silica
    Materialart: Dataset
    Format: text/tab-separated-values, 35 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2023-06-27
    Schlagwort(e): Age, 14C AMS; Age, 14C calibrated; Age, dated; Age, dated standard error; Calendar age; Calendar age, maximum/old; Calendar age, minimum/young; DEPTH, sediment/rock; Event label; GGC; GGC-55; Giant gravity corer; JPC; JPC-56; Jumbo Piston Core; Laboratory code/label
    Materialart: Dataset
    Format: text/tab-separated-values, 98 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2023-06-27
    Schlagwort(e): DEPTH, sediment/rock; JPC; JPC-56; Jumbo Piston Core; δ15N, organic matter
    Materialart: Dataset
    Format: text/tab-separated-values, 75 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2023-06-27
    Schlagwort(e): DEPTH, sediment/rock; GGC; GGC-55; Giant gravity corer; δ15N, organic matter
    Materialart: Dataset
    Format: text/tab-separated-values, 72 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2023-06-27
    Schlagwort(e): Accumulation rate, opal, per year; DEPTH, sediment/rock; JPC; JPC-56; Jumbo Piston Core; Opal, biogenic silica
    Materialart: Dataset
    Format: text/tab-separated-values, 740 data points
    Standort Signatur Erwartet Verfügbarkeit
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