GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Document type
Keywords
Publisher
Language
Years
  • 1
    Online Resource
    Online Resource
    Biogeochemical cycling of iron and phosphorus under low oxygen conditions (2017)
    Kiel
    Details Availability
    Keywords: Hochschulschrift
    Description / Table of Contents: Benthic release of the key nutrients iron (Fe) and phosphorus (P) is enhanced from sediments that are impinged by oxygen-deficient bottom waters due to its diminished retention capacity for such redox sensitive elements. Suboxic to anoxic and sometimes even euxinic conditions are recently found in open ocean oxygen minimum zones (OMZs, e.g. Eastern Boundary Upwelling Systems) and marginal seas (e.g. the Black Sea and the Baltic Sea). Recent studies showed that OMZs expanded in the last decades and will further spread in the future. Due to the additional release of bioavailable key nutrients from the sediments in such high productivity regions, several feedback mechanisms can evolve. The scenarios range from positive to neutral and negative consequences on the evolution of the ocean’s oxygen levels. This controversial issue makes it crucial to investigate the biogeochemical cycling of Fe and P in OMZs
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource
    URL: http://nbn-resolving.de/urn:nbn:de:gbv:8-diss-212773
    URL: http://d-nb.info/1137509813/34
    URL: http://macau.uni-kiel.de/receive/dissertation_diss_00021277
    URN: urn:nbn:de:gbv:8-diss-212773
    DDC: 550
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 2
    facet.materialart.
    Unknown
    The DAM/DataHub portal and viewer: How to improve the visibility of my data? (2022)
    Details
    Publication Date: 2022-07-05
    Description: Slides of a presentation on the DAM/DataHub portal and viewer for the Digital Science Monday seminar series at GEOMAR. The talk amied to give an overview of the background and functions of the DAM/DataHub portal and viewer from AWI, GEOMAR and Hereon. The DAM/DataHub portal and viewer (marine-data.de) is a centralized access point to search and explore marine data harvested from different national data repositories (e.g. Pangaea, OceanRep, HCDC, etc.).
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: slideshow
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Talk
  • 3
    facet.materialart.
    Unknown
    Benthic Dinitrogen Fixation Traversing the Oxygen Minimum Zone Off Mauritania (NW Africa) (2017)
    Frontiers
    In:  Frontiers in Marine Science, 4 (390).
    Details
    Publication Date: 2020-02-06
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3389/fmars.2017.00390
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Benthic phosphorus cycling in the Peruvian oxygen minimum zone (2016)
    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 13 (5). pp. 1367-1386.
    Details
    Publication Date: 2019-09-23
    Description: Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P at six stations, including the analysis of particles from the water column, surface sediments, and pore fluids, as well as in situ benthic flux measurements. A major fraction of solid-phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m−2 d−1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC / TPP burial ratio. Benthic dissolved P fluxes were always higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating ongoing phosphorite formation. This is further supported by decreasing porewater phosphate concentrations with sediment depth, whereas solid-phase P concentrations were comparatively high.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.5194/bg-13-1367-2016
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions (2016)
    Elsevier
    In:  Earth and Planetary Science Letters, 454 . pp. 272-281.
    Details
    Publication Date: 2019-02-01
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1016/j.epsl.2016.09.025
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
    facet.materialart.
    Unknown
    On the isotope composition of reactive iron in marine sediments: Redox shuttle versus early diagenesis (2014)
    Elsevier
    In:  Chemical Geology, 389 . pp. 48-59.
    Details
    Publication Date: 2019-09-23
    Description: The isotope composition of reactive iron (Fe) in marine sediments and sedimentary rocks is a promising tool for identifying Fe sources and sinks across ocean basins. In addition to cross-basinal Fe redistribution, which can modify Fe isotope signatures, Fe minerals also undergo diagenetic redistribution during burial. The isotope fractionation associated with this redistribution does not affect the bulk isotope composition, but complicates the identification of mineral-specific isotope signatures. Here, we present new Fe isotope data for Peru margin sediments and revisit previously published data for sediments from the California margin to unravel the impact of early diagenesis on Fe isotope compositions of individual Fe pools. Sediments from oxic California margin sites are dominated by terrigenous Fe supply with Fe release from sediments having a negligible influence on the solid phase Fe isotope composition. The highly reactive Fe pool (sum of Fe bound to (oxyhydr)oxide, carbonate, monosulfide and pyrite) of these sediments has a light isotope composition relative to the bulk crust, which is consistent with earlier studies showing that continental weathering shifts the isotope composition of Fe (oxyhydr)oxides to lighter values. Ferruginous sedimentswithin the Peruvian oxygen minimumzone are depleted in Fe relative to the lithogenic background, which we attribute to extensive Fe release to the water column. The remaining highly reactive Fe pool has a heavier isotope composition compared to California margin sediments. This observation is in agreement with the general notion of an isotopically light benthic Fe efflux. Most of the reactive Fe delivered and retained in the sediment is transferred into authigenic mineral phases within the topmost 10 to 20 cm of the sediments. We observe a first-order relationship between the extent of pyritization of Fe monosulfide and the isotope composition of authigenic pyrite. With increasing pyritization, the isotope composition of authigenic pyrite approaches the isotope composition of the highly reactive Fe pool. We argue that the isotope composition of authigenic pyrite or other Fe minerals that may undergo pyritization may only be used to trace water column sources or sinks if the extent of pyritization is separately evaluated and either close to 100% or 0%. Alternatively, one may calculate the isotope composition of the highly reactive Fe pool, thereby avoiding isotope effects due to internal diagenetic redistribution. In depositional settings with high Fe but lowsulfide concentrations, source and sink signatures in the isotope composition of the highly reactive Fe pool may be compromised by sequestration of Fe within authigenic silicate minerals. Authigenic silicate minerals appear to be an important burial phase for reactive Fe below the Peruvian oxygen minimum zone.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2014.09.009
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
    facet.materialart.
    Unknown
    Benthic nitrogen cycling across Peruvian oxygen minimum zone surface sediments (2014)
    In:  [Poster] In: ASLO Aquatic Sciences Meeting 2014, 23.-28.02.2014, Honolulu, Hawaii .
    Details
    Publication Date: 2015-01-06
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Poster
  • 8
    facet.materialart.
    Unknown
    An experimental and modeling investigation of sediment nutrient cycling during further deoxygenation on the Peruvian margin (2018)
    In:  [Poster] In: Ocean Deoxygenation Conference, 03.09.-07.09.2018, Kiel, Germany .
    Details
    Publication Date: 2018-12-04
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Poster
  • 9
    facet.materialart.
    Unknown
    Organic carbon production, mineralization and preservation on the Peruvian margin (2015)
    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 12 . pp. 1537-1559.
    Details
    Publication Date: 2019-09-23
    Description: Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (〈 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (〈 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.5194/bg-12-1537-2015
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
    facet.materialart.
    Unknown
    Biological nitrate transport in sediments on the Peruvian margin mitigates benthic sulfide emissions and drives pelagic N loss during stagnation events (2016)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 112 . pp. 123-136.
    Details
    Publication Date: 2019-09-23
    Description: Highlights • Very high rates of dissimilatory nitrate reduction to ammonium by Thioploca. • Non-steady state model predicts Thioploca survival on intracellular nitrate reservoir. • Ammonium release by Thioploca may be coupled to pelagic N loss by anammox. • Thioploca may contribute to anammox long after bottom water nitrate disappearance. • Model indicates that benthic foraminifera account for 90% of benthic N2 production. Abstract Benthic N cycling in the Peruvian oxygen minimum zone (OMZ) was investigated at ten stations along 12oS from the middle shelf (74 m) to the upper slope (1024 m) using in situ flux measurements, sediment biogeochemistry and modelling. Middle shelf sediments were covered by mats of the filamentous bacteria Thioploca spp. and contained a large ‘hidden’ pool of nitrate that was not detectable in the porewater. This was attributed to a biological nitrate reservoir stored within the bacteria to oxidize sulfide to sulfate during ‘dissimilatory nitrate reduction to ammonium’ (DNRA). The extremely high rates of DNRA on the shelf (15.6 mmol m-2 d-1 of N), determined using an empirical steady-state model, could easily supply all the ammonium requirements for anammox in the water column. The model further showed that denitrification by foraminifera may account for 90% of N2 production at the lower edge of the OMZ. At the time of sampling, dissolved oxygen was below detection limit down to 400 m and the water body overlying the shelf had stagnated, resulting in complete depletion of nitrate and nitrite. A decrease in the biological nitrate pool was observed on the shelf during fieldwork concomitant with a rise in porewater sulfide levels in surface sediments to 2 mM. Using a non-steady state model to simulate this natural anoxia experiment, these observations were shown to be consistent with Thioploca surviving on a dwindling intracellular nitrate reservoir to survive the stagnation period. The model shows that sediments hosting Thioploca are able to maintain high ammonium fluxes for many weeks following stagnation, potentially sustaining pelagic N loss by anammox. In contrast, sulfide emissions remain low, reducing the economic risk to the Peruvian fishery by toxic sulfide plume development.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    DOI: 10.1016/j.dsr.2016.02.013
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...