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  • 1
    Online Resource
    Online Resource
    Iron Cycle in Oceans. (2016)
    Newark :John Wiley & Sons, Incorporated,
    Details
    Keywords: Biogeochemical cycles. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (137 pages)
    Edition: 1st ed.
    ISBN: 9781119136866
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=4785169
    DDC: 577.14
    Language: English
    Note: Cover -- Title Page -- Copyright -- Contents -- Preface -- 1. Iron Speciation in Seawater -- 1.1. The chemical element -- 1.2. Iron speciation -- 1.2.1. Inorganic speciation -- 1.2.2. Organic speciation -- 1.2.3. Redox speciation -- 1.2.4. Operational definitions of iron speciation -- 1.3. Applying speciation -- 1.3.1. Solubility -- 1.3.2. Photochemistry -- 1.3.3. Cultures in artificial seawater with well-defined iron speciation -- 1.3.4. Iron bioavailability: the chemical perspective -- 1.3.5. Iron speciation on geological timescales -- 2. Analytical Methods -- 2.1. Trace-metal clean sampling techniques -- 2.2. Processing of the sample before measurement of concentrations -- 2.3. Particle collection -- 2.4. Iron determination -- 2.4.1. Historical perspective -- 2.4.2. Flow injection analysis -- 2.4.3. Electrochemistry -- 2.4.4. Mass spectrometry -- 2.4.5. Iron reference samples -- 2.4.6. Probing iron bioavailability -- 3. Modeling Methods -- 3.1. Overview -- 3.2. Modeling frameworks -- 3.3. Modeling iron cycle processes -- 3.3.1. Modeling iron supply -- 3.3.2. Modeling iron speciation -- 3.3.3. Modeling biological uptake of iron -- 3.3.4. Modeling iron regeneration -- 3.4. Synthesis -- 4. Iron Sources -- 4.1. Overview -- 4.2. Dust deposition -- 4.3. River supply -- 4.4. Continental margins -- 4.5. Hydrothermalism -- 4.6. Glaciers, icebergs and sea ice -- 4.7. Submarine groundwater discharge -- 4.8. Synthesis -- 5. Iron Cycling in the Ocean -- 5.1. The biological iron demand -- 5.1.1. Phytoplankton iron requirement -- 5.1.2. Iron requirements of heterotrophic organisms -- 5.2. Iron cycling in the surface ocean -- 5.3. Iron export and its cycling below the mixed layer -- 6. Dissolved Iron Distributions in the Ocean -- 6.1. Overview -- 6.2. Temporal evolution in the number of observations. , 6.3. The contemporary view of the distribution of iron in the ocean -- 6.4. The vertical profile of iron -- 6.5. Synthesis -- 7. The Iron Hypothesis -- 7.1. Introduction -- 7.2. From bottle incubations to mesoscale experiments -- 7.3. Natural iron fertilization -- 7.4. Paleo iron hypothesis -- 7.5. Large-scale iron fertilization: climate engineering -- Bibliography -- Index -- Other titles from iSTE in Earth Systems - Environmental Engineering -- EULA.
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  • 2
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    On the effects of circulation, sediment resuspension and biological incorporation by diatoms in an ocean model of aluminium, link to model data (2014)
    PANGAEA
    In:  Supplement to: van Hulten, Marco M P; Sterl, Andreas; Middag, Rob; de Baar, Hein J W; Gehlen, Marion; Dutay, Jean-Claude; Tagliabue, Alessandro (2014): On the effects of circulation, sediment resuspension and biological incorporation by diatoms in an ocean model of aluminium. Biogeosciences, 11(14), 3757-3779, https://doi.org/10.5194/bg-11-3757-2014
    Details
    Publication Date: 2023-01-13
    Description: The distribution of dissolved aluminium in the West Atlantic Ocean shows a mirror image with that of dissolved silicic acid, hinting at intricate interactions between the ocean cycling of Al and Si. The marine biogeochemistry of Al is of interest because of its potential impact on diatom opal remineralisation, hence Si availability. Furthermore, the dissolved Al concentration at the surface ocean has been used as a tracer for dust input, dust being the most important source of the bio-essential trace element iron to the ocean. Previously, the dissolved concentration of Al was simulated reasonably well with only a dust source, and scavenging by adsorption on settling biogenic debris as the only removal process. Here we explore the impacts of (i) a sediment source of Al in the Northern Hemisphere (especially north of ~ 40° N), (ii) the imposed velocity field, and (iii) biological incorporation of Al on the modelled Al distribution in the ocean. The sediment source clearly improves the model results, and using a different velocity field shows the importance of advection on the simulated Al distribution. Biological incorporation appears to be a potentially important removal process. However, conclusive independent data to constrain the Al / Si incorporation ratio by growing diatoms are missing. Therefore, this study does not provide a definitive answer to the question of the relative importance of Al removal by incorporation compared to removal by adsorptive scavenging.
    Type: Dataset
    Format: application/zip, 2 GBytes
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    DATA PANGAEA
  • 3
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    Model output of manganese concentrations from a global ocean circulation model, link to files in NetCDF format (2017)
    PANGAEA
    In:  Supplement to: van Hulten, Marco M P; Middag, Rob; Dutay, Jean-Claude; de Baar, Hein J W; Roy-Barman, Matthieu; Gehlen, Marion; Tagliabue, Alessandro; Sterl, Andreas (2017): Manganese in the west Atlantic Ocean in the context of the first global ocean circulation model of manganese. Biogeosciences, 14(5), 1123-1152, https://doi.org/10.5194/bg-14-1123-2017
    Details
    Publication Date: 2023-02-24
    Description: Dissolved manganese (Mn) is a biologically essential element. Moreover, its oxidised form is involved in removing itself and several other trace elements from ocean waters. Here we report the longest thus far (17500 km length) full-depth ocean section of dissolved Mn in the west Atlantic Ocean, comprising 1320 data values of high accuracy. This is the GA02 transect that is part of the GEOTRACES programme, which aims to understand trace element distributions. The goal of this study is to combine these new observations with new, state-of-the-art, modelling to give a first assessment of the main sources and redistribution of Mn throughout the ocean. To this end, we simulate the distribution of dissolved Mn using a global-scale circulation model. This first model includes simple parameterisations to account for the sources, processes and sinks of Mn in the ocean. Oxidation and (photo)reduction, aggregation and settling, as well as biological uptake and remineralisation by plankton are included in the model. Our model provides, together with the observations, the following insights: – The high surface concentrations of manganese are caused by the combination of photoreduction and sources contributing to the upper ocean. The most important sources are sediments, dust, and, more locally, rivers. – Observations and model simulations suggest that surface Mn in the Atlantic Ocean moves downwards into the southward-flowing North Atlantic Deep Water (NADW), but because of strong removal rates there is no elevated concentration of Mn visible any more in the NADW south of 40° N. – The model predicts lower dissolved Mn in surface waters of the Pacific Ocean than the observed concentrations. The intense oxygen minimum zone (OMZ) in subsurface waters is deemed to be a major source of dissolved Mn also mixing upwards into surface waters, but the OMZ is not well represented by the model. Improved high-resolution simulation of the OMZ may solve this problem. – There is a mainly homogeneous background concentration of dissolved Mn of about 0.10–0.15 nM throughout most of the deep ocean. The model reproduces this by means of a threshold on particulate manganese oxides of 25 pM, suggesting that a minimal concentration of particulate Mn is needed before aggregation and removal become efficient. – The observed distinct hydrothermal signals are produced by assuming both a strong source and a strong removal of Mn near hydrothermal vents.
    Keywords: GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes
    Type: Dataset
    Format: application/zip, 393.1 MBytes
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    DATA PANGAEA
  • 4
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    Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates (2015)
    PANGAEA
    In:  Supplement to: Lambert, Fabrice; Tagliabue, Alessandro; Shaffer, Gary; Lamy, Frank; Winckler, Gisela; Farías, Laura; Gallardo, Laura; De Pol-Holz, Ricardo (2015): Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates. Geophysical Research Letters, 42(14), 6014-6023, https://doi.org/10.1002/2015GL064250
    Details
    Publication Date: 2023-10-19
    Description: Mineral dust aerosols play a major role in present and past climates. To date, we rely on climate models for estimates of dust fluxes to calculate the impact of airborne micronutrients on biogeochemical cycles. Here we provide a new global dust flux data set for Holocene and Last Glacial Maximum (LGM) conditions based on observational data. A comparison with dust flux simulations highlights regional differences between observations and models. By forcing a biogeochemical model with our new data set and using this model's results to guide a millennial-scale Earth System Model simulation, we calculate the impact of enhanced glacial oceanic iron deposition on the LGM-Holocene carbon cycle. On centennial timescales, the higher LGM dust deposition results in a weak reduction of 〈10 ppm in atmospheric CO2 due to enhanced efficiency of the biological pump. This is followed by a further ~10 ppm reduction over millennial timescales due to greater carbon burial and carbonate compensation.
    Type: Dataset
    Format: application/x-netcdf, 769.4 kBytes
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    DATA PANGAEA
  • 5
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    Nutrient co-limitation at the boundary of an oceanic gyre: Incubations during METEOR cruise M121 (2019)
    PANGAEA
    In:  Supplement to: Browning, Thomas J; Achterberg, Eric Pieter; Rapp, Insa; Engel, Anja; Bertrand, E M; Tagliabue, Alessandro; Moore, C Mark (2017): Nutrient co-limitation at the boundary of an oceanic gyre. Nature, 551(7679), 242-246, https://doi.org/10.1038/nature24063
    Details
    Publication Date: 2023-09-27
    Description: Nutrient limitation of oceanic primary production exerts a fundamental control on marine food webs and the flux of carbon into the deep ocean1. The extensive boundaries of the oligotrophic sub-tropical gyres collectively define the most extreme transition in ocean productivity, but little is known about nutrient limitation in these zones1,2,3,4. Here we present the results of full-factorial nutrient amendment experiments conducted at the eastern boundary of the South Atlantic gyre. We find extensive regions in which the addition of nitrogen or iron individually resulted in no significant phytoplankton growth over 48 hours. However, the addition of both nitrogen and iron increased concentrations of chlorophyll a by up to approximately 40-fold, led to diatom proliferation, and reduced community diversity. Once nitrogen–iron co-limitation had been alleviated, the addition of cobalt or cobalt-containing vitamin B12 could further enhance chlorophyll a yields by up to threefold. Our results suggest that nitrogen–iron co-limitation is pervasive in the ocean, with other micronutrients also approaching co-deficiency. Such multi-nutrient limitations potentially increase phytoplankton community diversity.
    Keywords: GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
  • 6
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    230Th global thorium database (2020)
    PANGAEA
    Details
    Publication Date: 2024-03-02
    Description: In this dataset we present a global compilation of over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the Late Holocene (0-5000 years ago, or 0-5 ka) and the Last Glacial Maximum (18.5-23.5 ka). Data have been screened for age control, errors, and lithogenic corrections. Overall quality levels were computed by summing each record's scores on the individual criteria. A record is optimal if it is based on a chronology that is constrained by δ18O or 14C and it provides both the raw nuclide concentrations and the associated errors. About one quarter of the records in the database achieved this highest quality level. The large majority of the records in the database are good, passing two of the three criteria, while the remaining quarter are of fair or poor quality.
    Keywords: Comment; DEPTH, water; Distance; Flag; Focusing factor; GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes; Identification; LATITUDE; LONGITUDE; Ocean; ORDINAL NUMBER; Quality level; Ratio; Reference/source; Thorium-230 excess, decay-corrected; Total sediment, flux; Uranium/Thorium ratio
    Type: Dataset
    Format: text/tab-separated-values, 15667 data points
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    DATA PANGAEA
  • 7
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    Seawater carbonate chemistry and the decrease of H+ concentration in the phycosphere and thickness of the pH boundary layer of marine diatoms Coscinodiscus wailesii (2022)
    PANGAEA
    Details
    Publication Date: 2024-03-15
    Description: Surface ocean pH is declining due to anthropogenic atmospheric CO2 uptake with a global decline of ~0.3 possible by 2100. Extracellular pH influences a range of biological processes, including nutrient uptake, calcification and silicification. However, there are poor constraints on how pH levels in the extracellular microenvironment surrounding phytoplankton cells (the phycosphere) differ from bulk seawater. This adds uncertainty to biological impacts of environmental change. Furthermore, previous modelling work suggests that phycosphere pH of small cells is close to bulk seawater, and this has not been experimentally verified. Here we observe under 140 μmol photons/m**2/s the phycosphere pH of Chlamydomonas concordia (5 µm diameter), Emiliania huxleyi (5 µm), Coscinodiscus radiatus (50 µm) and C. wailesii (100 µm) are 0.11 ± 0.07, 0.20 ± 0.09, 0.41 ± 0.04 and 0.15 ± 0.20 (mean ± SD) higher than bulk seawater (pH 8.00), respectively. Thickness of the pH boundary layer of C. wailesii increases from 18 ± 4 to 122 ± 17 µm when bulk seawater pH decreases from 8.00 to 7.78. Phycosphere pH is regulated by photosynthesis and extracellular enzymatic transformation of bicarbonate, as well as being influenced by light intensity and seawater pH and buffering capacity. The pH change alters Fe speciation in the phycosphere, and hence Fe availability to phytoplankton is likely better predicted by the phycosphere, rather than bulk seawater. Overall, the precise quantification of chemical conditions in the phycosphere is crucial for assessing the sensitivity of marine phytoplankton to ongoing ocean acidification and Fe limitation in surface oceans.
    Keywords: Acid-base regulation; Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Coscinodiscus wailesii; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Hydrogen ion concentration; Laboratory experiment; Laboratory strains; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phytoplankton; Proton gradients; Salinity; Single species; Species, unique identification; Temperature, water; Thickness; Treatment; Type
    Type: Dataset
    Format: text/tab-separated-values, 3286 data points
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    DATA PANGAEA
  • 8
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    Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP) (2017)
    Copernicus Publications (EGU)
    In:  Geoscientific Model Development, 10 (6). pp. 2169-2199.
    Details
    Publication Date: 2020-02-06
    Description: The Ocean Model Intercomparison Project (OMIP) focuses on the physics and biogeochemistry of the ocean component of Earth system models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). OMIP aims to provide standard protocols and diagnostics for ocean models, while offering a forum to promote their common assessment and improvement. It also offers to compare solutions of the same ocean models when forced with reanalysis data (OMIP simulations) vs. when integrated within fully coupled Earth system models (CMIP6). Here we detail simulation protocols and diagnostics for OMIP's biogeochemical and inert chemical tracers. These passive-tracer simulations will be coupled to ocean circulation models, initialized with observational data or output from a model spin-up, and forced by repeating the 1948–2009 surface fluxes of heat, fresh water, and momentum. These so-called OMIP-BGC simulations include three inert chemical tracers (CFC-11, CFC-12, SF6) and biogeochemical tracers (e.g., dissolved inorganic carbon, carbon isotopes, alkalinity, nutrients, and oxygen). Modelers will use their preferred prognostic BGC model but should follow common guidelines for gas exchange and carbonate chemistry. Simulations include both natural and total carbon tracers. The required forced simulation (omip1) will be initialized with gridded observational climatologies. An optional forced simulation (omip1-spunup) will be initialized instead with BGC fields from a long model spin-up, preferably for 2000 years or more, and forced by repeating the same 62-year meteorological forcing. That optional run will also include abiotic tracers of total dissolved inorganic carbon and radiocarbon, CTabio and 14CTabio, to assess deep-ocean ventilation and distinguish the role of physics vs. biology. These simulations will be forced by observed atmospheric histories of the three inert gases and CO2 as well as carbon isotope ratios of CO2. OMIP-BGC simulation protocols are founded on those from previous phases of the Ocean Carbon-Cycle Model Intercomparison Project. They have been merged and updated to reflect improvements concerning gas exchange, carbonate chemistry, and new data for initial conditions and atmospheric gas histories. Code is provided to facilitate their implementation.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.5194/gmd-10-2169-2017
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    The GEOTRACES Intermediate Data Product 2017 (2018)
    Elsevier
    In:  Chemical Geology, 493 . pp. 210-223.
    Details
    Publication Date: 2021-02-08
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2018.05.040
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Hydrothermal contribution to the oceanic dissolved iron inventory (2010)
    Nature Publishing Group
    In:  Nature Geoscience, 3 (4). pp. 252-256.
    Details
    Publication Date: 2017-08-28
    Description: Iron limits phytoplankton growth and hence the biological carbon pump in the Southern Ocean1. Models assessing the impacts of iron on the global carbon cycle generally rely on dust input and sediment resuspension as the predominant sources2, 3. Although it was previously thought that most iron from deep-ocean hydrothermal activity was inaccessible to phytoplankton because of the formation of particulates4, it has been suggested that iron from hydrothermal activity5, 6, 7 may be an important source of oceanic dissolved iron8, 9, 10, 11, 12, 13. Here we use a global ocean model to assess the impacts of an annual dissolved iron flux of approximately 9×108 mol, as estimated from regional observations of hydrothermal activity11, 12, on the dissolved iron inventory of the world’s oceans. We find the response to the input of hydrothermal dissolved iron is greatest in the Southern Hemisphere oceans. In particular, observations of the distribution of dissolved iron in the Southern Ocean3 (Chever et al., manuscript in preparation; Bowie et al., manuscript in preparation) can be replicated in our simulations only when our estimated iron flux from hydrothermal sources is included. As the hydrothermal flux of iron is relatively constant over millennial timescales14, we propose that hydrothermal activity can buffer the oceanic dissolved iron inventory against shorter-term fluctuations in dust deposition.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/ngeo818
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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