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  • 11
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    Concentrations of organic carbon, nitrogen and phosphorus in waters of the tropical North Atlantic at Station POS284-156 (2008)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Bottle, Niskin 10-L; Carbon, organic, particulate; Carbon, organic, total; Carbon, organic, total, standard deviation; DEPTH, water; NIS_10L; Nitrogen, organic, particulate; North Atlantic; Phosphorus, organic, particulate; POS284; POS284_156; Poseidon
    Type: Dataset
    Format: text/tab-separated-values, 52 data points
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  • 12
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    Concentrations of organic carbon, nitrogen and phosphorus in waters of the tropical North Atlantic at Station POS284-183 (2008)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Bottle, Niskin 10-L; Carbon, organic, particulate; Carbon, organic, total; Carbon, organic, total, standard deviation; DEPTH, water; NIS_10L; Nitrogen, organic, particulate; North Atlantic; Phosphorus, organic, particulate; POS284; POS284_183; Poseidon
    Type: Dataset
    Format: text/tab-separated-values, 33 data points
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  • 13
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    Concentrations of organic carbon, nitrogen and phosphorus in waters of the tropical North Atlantic at Station POS284-173 (2008)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Bottle, Niskin 10-L; Carbon, organic, particulate; Carbon, organic, total; Carbon, organic, total, standard deviation; DEPTH, water; NIS_10L; Nitrogen, organic, particulate; North Atlantic; Phosphorus, organic, particulate; POS284; POS284_173; Poseidon
    Type: Dataset
    Format: text/tab-separated-values, 51 data points
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  • 14
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    Potential impact of DOM accumulation on fCO2 and carbonate ion computations in ocean acidification experiments (2014)
    PANGAEA
    In:  Supplement to: Koeve, Wolfgang; Oschlies, Andreas (2012): Potential impact of DOM accumulation on fCO2 and carbonate ion computations in ocean acidification experiments. Biogeosciences, 9(10), 3787-3798, https://doi.org/10.5194/bg-9-3787-2012
    Details
    Publication Date: 2023-02-24
    Description: Culture and mesocosm experiments are often carried out under high initial nutrient concentrations, yielding high biomass concentrations that in turn often lead to a substantial build-up of DOM. In such experiments, DOM can reach concentrations much higher than typically observed in the open ocean. To the extent that DOM includes organic acids and bases, it will contribute to the alkalinity of the seawater contained in the experimental device. Our analysis suggests that whenever substantial amounts of DOM are produced during the experiment, standard computer programmes used to compute CO2 fugacity can underestimate true fCO2 significantly when the computation is based on AT and CT. Unless the effect of DOM-alkalinity can be accounted for, this might lead to significant errors in the interpretation of the system under consideration with respect to the experimentally applied CO2 perturbation. Errors in the inferred fCO2 can misguide the development of parameterisations used in simulations with global carbon cycle models in future CO2-scenarios. Over determination of the CO2-system in experimental ocean acidification studies is proposed to safeguard against possibly large errors in estimated fCO2.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 15
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    Reanalysis of vertical mixing in mesocosm experiments: PeECE III and KOSMOS 2013 (2019)
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Description: Here we provide optimised vertical eddy diffusivity estimates for the PeECE III and KOSMOS 2013 mesocosm experiment, obtained from a model-based reanalysis. These diffusivities are derived from the observed temperature and salinity profiles that have been published in Schulz et al., 2008. Furthermore, we make our model code available, providing an adjustable tool to simulate vertical mixing in any other pelagic mesocosm. We also provide the interpolated and regridded temperature and salinity profiles of the PeECE III experiment as well as the density profiles which we calculated from the temperature and salinity profiles using the R package seacarb (Lavigne et al., 2011). These data files are required as input to run simulations of the PeECE III experiment with the 1D mesocosm mixing model. The columns of the environmental files (required input files for the model) from left to right are: Experiment year, month, day, Julian day, photosynthetically active radiation (PAR) [W/m^2], temperature [C], salinity [PSU], CO2 concentration [ppm], wind speed [m/s]. The rows list the respective value of each hour of the experiment. Temperature and salinity in this table are hourly interpolated values of the daily measurements published by the PeECE III team (2005). PAR has been calculated from global radiation data of Bergen provided by Olseth et al., 2005. In the temperature, salinity and density files, the rows indicate the depth (0.5 m resolution, the first row is the surface, the last row is the bottom), whereas the columns indicate the experiment time at an hourly resolution.
    Keywords: File content; File format; File name; File size; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 20 data points
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  • 16
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    Model results of sensitivity experiments for marine nitrogen cycle in four NetCDF files
    PANGAEA
    In:  Supplement to: Landolfi, Angela; Dietze, Heiner; Koeve, Wolfgang; Oschlies, Andreas (2013): Overlooked runaway feedback in the marine nitrogen cycle: the vicious cycle. Biogeosciences, 10(3), 1351-1363, https://doi.org/10.5194/bg-10-1351-2013
    Details
    Publication Date: 2023-05-12
    Description: The marine nitrogen (N) inventory is thought to be stabilized by negative feedback mechanisms that reduce N inventory excursions relative to the more slowly overturning phosphorus inventory. Using a global biogeochemical ocean circulation model we show that negative feedbacks stabilizing the N inventory cannot persist if a close spatial association of N2 fixation and denitrification occurs. In our idealized model experiments, nitrogen deficient waters, generated by denitrification, stimulate local N2 fixation activity. But, because of stoichiometric constraints, the denitrification of newly fixed nitrogen leads to a net loss of N. This can enhance the N deficit, thereby triggering additional fixation in a vicious cycle, ultimately leading to a runaway N loss. To break this vicious cycle, and allow for stabilizing negative feedbacks to occur, inputs of new N need to be spatially decoupled from denitrification. Our idealized model experiments suggest that factors such as iron limitation or dissolved organic matter cycling can promote such decoupling and allow for negative feedbacks that stabilize the N inventory. Conversely, close spatial co-location of N2 fixation and denitrification could lead to net N loss.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Description; File format; File size; modelled; Uniform resource locator/link to model result file
    Type: Dataset
    Format: text/tab-separated-values, 16 data points
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  • 17
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    Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone (2015)
    PANGAEA
    In:  Supplement to: Kalvelage, Tim; Lavik, Gaute; Lam, Phyllis; Contreras, Sergio; Arteaga, Lionel; Löscher, Carolin R; Oschlies, Andreas; Stramma, Lothar; Kuypers, Marcel MM (2013): Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone. Nature Geoscience, 6(3), 228-234, https://doi.org/10.1038/ngeo1739
    Details
    Publication Date: 2023-10-28
    Description: Oxygen minimum zones are expanding globally, and at present account for around 20-40% of oceanic nitrogen loss. Heterotrophic denitrification and anammox-anaerobic ammonium oxidation with nitrite-are responsible for most nitrogen loss in these low-oxygen waters. Anammox is particularly significant in the eastern tropical South Pacific, one of the largest oxygen minimum zones globally. However, the factors that regulate anammox-driven nitrogen loss have remained unclear. Here, we present a comprehensive nitrogen budget for the eastern tropical South Pacific oxygen minimum zone, using measurements of nutrient concentrations, experimentally determined rates of nitrogen transformation and a numerical model of export production. Anammox was the dominant mode of nitrogen loss at the time of sampling. Rates of anammox, and related nitrogen transformations, were greatest in the productive shelf waters, and tailed off with distance from the coast. Within the shelf region, anammox activity peaked in both upper and bottom waters. Overall, rates of nitrogen transformation, including anammox, were strongly correlated with the export of organic matter. We suggest that the sinking of organic matter, and thus the release of ammonium into the water column, together with benthic ammonium release, fuel nitrogen loss from oxygen minimum zones.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 6 datasets
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  • 18
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    Jelly biomass sinking speed reveals a fast carbon export mechanism (2013)
    PANGAEA
    In:  Supplement to: Lebrato, Mario; Mendes, Pedro André; Steinberg, Deborah K; Birsa, Laura M; Benavides, Mar; Oschlies, Andreas (2013): Jelly biomass sinking speed reveals a fast carbon export mechanism. Limnology and Oceanography, 58(3), 1113-1122, https://doi.org/10.4319/lo.2013.58.3.1113
    Details
    Publication Date: 2024-02-17
    Description: Sinking of gelatinous zooplankton biomass is an important component of the biological pump removing carbon from the upper ocean. The export efficiency, e.g., how much biomass reaches the ocean interior sequestering carbon, is poorly known because of the absence of reliable sinking speed data. We measured sinking rates of gelatinous particulate organic matter (jelly-POM) from different species of scyphozoans, ctenophores, thaliaceans, and pteropods, both in the field and in the laboratory in vertical columns filled with seawater using high-quality video. Using these data, we determined taxon-specific jelly-POM export efficiencies using equations that integrate biomass decay rate, seawater temperature, and sinking speed. Two depth scenarios in several environments were considered, with jelly-POM sinking from 200 and 600 m in temperate, tropical, and polar regions. Jelly-POM sank on average between 850 and 1500 m/d (salps: 800-1200 m/d; ctenophores: 1200-1500 m/d; scyphozoans: 1000-1100 m d; pyrosomes: 1300 m/d). High latitudes represent a fast-sinking and low-remineralization corridor, regardless of species. In tropical and temperate regions, significant decomposition takes place above 1500 m unless jelly-POM sinks below the permanent thermocline. Sinking jelly-POM sequesters carbon to the deep ocean faster than anticipated, and should be incorporated into biogeochemical and modeling studies to provide more realistic quantification of export via the biological carbon pump worldwide.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 19
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    Modeled uncertainties in marine N2O emissions with links to source files (52 MB, zipped) (2014)
    PANGAEA
    In:  Supplement to: Zamora, Lauren M; Oschlies, Andreas (2014): Surface nitrification: a major uncertainty in marine N2O emissions. Geophysical Research Letters, 41(12), 4247-4253, https://doi.org/10.1002/2014GL060556
    Details
    Publication Date: 2024-02-01
    Description: The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (〉100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to ~1.6 Tg N/yr, or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr, or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by 〈15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.
    Keywords: SOPRAN; Surface Ocean Processes in the Anthropocene
    Type: Dataset
    Format: application/zip, 52.6 MBytes
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  • 20
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    Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean (2020)
    National Academy of Sciences
    Details
    Publication Date: 2020-08-25
    Description: Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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