GLORIA

GEOMAR Library Ocean Research Information Access

X
Your search history is empty.
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
Years
  • 1
    facet.materialart.
    Unknown
    The biogeochemical impact of glacial meltwater from Southwest Greenland (2019)
    Elsevier
    In:  Progress in Oceanography, 176 . Art.Nr. 102126.
    Details
    Publication Date: 2022-01-31
    Description: Highlights • Novel multi-disciplinary approach to tracing freshwater and particle transport into boundary currents; • Significant glacial inputs reach coastal waters and are transported rapidly offshore; • Low surface water dissolved silicon concentrations maintained by diatom activity despite strong glacial and benthic supplies. Abstract Biogeochemical cycling in high-latitude regions has a disproportionate impact on global nutrient budgets. Here, we introduce a holistic, multi-disciplinary framework for elucidating the influence of glacial meltwaters, shelf currents, and biological production on biogeochemical cycling in high-latitude continental margins, with a focus on the silica cycle. Our findings highlight the impact of significant glacial discharge on nutrient supply to shelf and slope waters, as well as surface and benthic production in these regions, over a range of timescales from days to thousands of years. Whilst biological uptake in fjords and strong diatom activity in coastal waters maintains low dissolved silicon concentrations in surface waters, we find important but spatially heterogeneous additions of particulates into the system, which are transported rapidly away from the shore. We expect the glacially-derived particles – together with biogenic silica tests – to be cycled rapidly through shallow sediments, resulting in a strong benthic flux of dissolved silicon. Entrainment of this benthic silicon into boundary currents may supply an important source of this key nutrient into the Labrador Sea, and is also likely to recirculate back into the deep fjords inshore. This study illustrates how geochemical and oceanographic analyses can be used together to probe further into modern nutrient cycling in this region, as well as the palaeoclimatological approaches to investigating changes in glacial meltwater discharge through time, especially during periods of rapid climatic change in the Late Quaternary.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    DOI: 10.1016/j.pocean.2019.102126
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    facet.materialart.
    Unknown
    Deglacial diatom production in the tropical North Atlantic driven by enhanced silicic acid supply (2016)
    Elsevier
    Details
    Publication Date: 2023-08-01
    Description: Major shifts in ocean circulation are thought to be responsible for abrupt changes in temperature and atmospheric CO2 during the last deglaciation, linked to variability in meridional heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2 rise, including enhanced diatom production in regions such as the tropical Atlantic. However, it remains unclear as to whether this diatom production was driven by enhanced wind-driven upwelling or density-driven vertical mixing, or by elevated thermocline concentrations of silicic acid supplied to the surface at a constant rate. Here, we demonstrate that silicic acid supply at depth in the NE Atlantic was enhanced during the abrupt climate events of the deglaciation. We use marine sediment archives to show that an increase in diatom production during abrupt climate shifts could only occur in regions of the NE Atlantic where the deep supply of silicic acid could reach the surface. The associated changes are indicative of enhanced regional wind-driven upwelling and/or weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced thermocline concentrations of silicic acid suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
    facet.materialart.
    Unknown
    Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle (2020)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2023-02-08
    Description: 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 decreases by 0.6‰ from a background of 1‰ coeval with the CIE, while sponge δ30Si remains consistent at 0.2‰. Using a box model to test the Si cycle response to various scenarios, we find the data are best explained by a weak silicate weathering feedback, implying the recovery was mostly driven by nondiatom organic carbon burial, the other major long‐term carbon sink. We find no resolvable evidence for a volcanic trigger for carbon release, or for a change in regional oceanography. Better understanding of radiolarian Si isotope fractionation and more Si isotope records spanning the PETM are needed to confirm the global validity of these conclusions, but they highlight how the coupling between the silica and carbon cycles can be exploited to yield insight into the functioning of the Earth system.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Mg/Ca-Temperature Calibration of Polar Benthic foraminifera species for reconstruction of bottom water temperatures on the Antarctic shelf (2020)
    In:  EPIC3Geochimica et Cosmochimica Acta, 283, pp. 54-66, ISSN: 00167037
    Details
    Publication Date: 2020-07-15
    Description: Benthic foraminifera Mg/Ca is a well-established bottom water temperature (BWT) proxy used in paleoclimate studies. The relationship between Mg/Ca and BWT for numerous species has been determined using core-top and culturing studies. However, the scarcity of calcareous microfossils in Antarctic shelf sediments and poorly defined calibrations at low temperatures has limited the use of the foraminiferal Mg/Ca paleothermometer in ice proximal Antarctic sediments. Here we present paired ocean temperature and modern benthic foraminifera Mg/Ca data for three species, Trifarina angulosa, Bulimina aculeata, and Globocassidulina subglobosa, but with a particular focus on Trifarina angulosa. The core-top data from several Antarctic sectors span a BWT range of −1.7 to +1.2 °C and constrain the relationship between Mg/Ca and cold temperatures. We compare our results to published lower-latitude core-top data for species in the same or related genera, and in the case of Trifarina angulosa, produce a regional calibration. The resulting regional equation for Trifarina angulosa is Temperature (°C) = (Mg/Ca −1.14 ± 0.035)/0.069 ± 0.033). Addition of our Trifarina angulosa data to the previously published Uvigerina spp. dataset provides an alternative global calibration, although some data points appear to be offset from this relationship and are discussed. Mg-temperature relationships for Bulimina aculeata and Globocassidulina subglobosa are also combined with previously published data to produce calibration equations of Temperature (°C) = (Mg/Ca-1.04 ± 0.07)/0.099 ± 0.01 and Temperature (°C) = (Mg/Ca-0.99 ± 0.03)/0.087 ± 0.01, respectively. These refined calibrations highlight the potential utility of benthic foraminifera Mg/Ca-paleothermometry for reconstructing past BWT in Antarctic margin settings.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 5
    facet.materialart.
    Unknown
    Pore water, core incubation, and sponge geochemical data from Greenland margin and the Labrador Sea (2019)
    PANGAEA
    In:  Supplement to: Ng, Hong Chin; Cassarino, Lucie; Pickering, Rebecca A; Woodward, E Malcolm S; Hammond, Samantha J; Hendry, Katharine R (2020): Sediment efflux of silicon on the Greenland margin and implications for the marine silicon cycle. Earth and Planetary Science Letters, 529, 115877, https://doi.org/10.1016/j.epsl.2019.115877
    Details
    Publication Date: 2024-07-19
    Description: The dataset contains pore water and core incubation silicic acid concentration and isotope measurements, sponge silicon isotope measurements, and pore water major and trace elemental concentrations obtained from seven sediment cores collected from the Greenland margin and the Labrador Sea. The samples were collected as part of the European Research Council project ICY-LAB (ERC-2015-STG grant agreement number 678371).
    Keywords: core incubation; geochemical archives; ICY-LAB; Isotope CYcling in the LABrador Sea; isotopes; pore water; Porifera; silicic acid
    Type: dataset publication series
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 6
    facet.materialart.
    Unknown
    High-Resolution Vertical Terrain of a Deep-Sea Cliff offshore Greenland and the Associated Epibenthic Fauna (2021)
    PANGAEA
    Details
    Publication Date: 2024-07-19
    Description: We used a multibeam echosounder (Reson7125) front-mounted onto the ROV Isis (Dive D333, DY081 expedition) to map the terrain of a vertical feature marking the edge of a deep-sea glacial trough (Labrador Sea, [63°51.9'N, 53°16.9'W, depth: 650 to 800 m]). After correction of the ROV navigation (i.e. merging of USBL and DVL), bathymetry [m] and backscatter [nominal unit] were extracted at a resolution of 0.3 m and different terrain descriptors were computed: Slope, Bathymetric Position Index (BPI), Terrain Ruggedness Index, Roughness, Mean and Gaussian curvatures and orientations (Northness and Eastness), at scales of 0.9, 3 and 9 m. Using a Principal Component Analysis (PCA), the terrain descriptors enabled to retrieve 4 terrain clusters and their associated confusion index, to investigate the spatial heterogeneity of the terrain. This approach also underlined the presence of geomorphic features in the wall terrain. The extraction of the backscatter intensity for the first time considering vertical terrains, opens space for further acquisition and processing development. Using photographs collected by the ROV Isis (Dive D334, DY081 expedition), epibenthic fauna was annotated. Each image was linked to a terrain cluster in the 3D space and pooled into 20-m² bins of images. A Bray-Curtis dissimilarity matrix was constructed from morphospecies abundances. This enabled to test for differences of assemblage composition among clusters. Few species appeared more abundant in particular clusters such as L. pertusa in high-roughness cluster. However, nMDS suggested differences in assemblage composition but these dissimilarities were not strongly delineated. Whereas the design of this study may have limited distinctive differences among assemblages, this shows the potential of this cost-effective method of top-down habitat mapping to be applied in undersampled benthic habitat in order to provide a priori knwoledge for defining appropriate sampling design.
    Keywords: acoustic data; CLASS; Climate Linked Atlantic Sector Science; deep-water vertical cliff; DY081; fine-scale spatial patterns; Greenland glacial trough; High-resolution terrain; iAtlantic; ICY-LAB; Integrated Assessment of Atlantic Marine Ecosystems in Space and Time; Isotope CYcling in the LABrador Sea; Labrador Sea; marine habitat mapping; Multibeam Echosounder; ROV; suspension-feeding community; terrain point cloud; top-down habitat mapping; underwater exploration; unsupervised terrain clustering; Vertical mapping
    Type: dataset bundled publication
    Format: application/zip, 2 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 7
    facet.materialart.
    Unknown
    North Atlantic seawater bottle data collected during RRS Discovery cruise DY081 (2018)
    PANGAEA
    In:  Supplement to: Hendry, Katharine R; Huvenne, Veerle A I; Robinson, Laura F; Annett, Amber; Badger, Marcus P S; Jacobel, Allison W; Ng, Hong Chin; Opher, Jacob; Pickering, Rebecca A; Taylor, Michelle L; Bates, Stephanie L; Cooper, Adam; Cushman, Grace G; Goodwin, Claire; Hoy, Shannon Kelsey; Rowland, George Henry; Samperiz, Ana; Williams, James A; Achterberg, Eric Pieter; Arrowsmith, Carol; Brearley, J Alexander; Henley, Sian Frances; Krause, Jeffrey W; Leng, Melanie J; Li, Tao; McManus, Jerry F; Meredith, Michael P; Perkins, Rupert; Woodward, E Malcolm S (2019): The biogeochemical impact of glacial meltwater from Southwest Greenland. Progress in Oceanography, 176, 102126, https://doi.org/10.1016/j.pocean.2019.102126
    Details
    Publication Date: 2024-07-19
    Description: DY081 was the first fieldwork component of a European Research Council funded project, ICY-LAB, led by Dr. K. Hendry from the University of Bristol to study nutrient cycling in the North Atlantic. This data release contains seawater bottle data collected during DY081 by standard CTD rosette, remotely operated vehicle and Tow fish, together with ancillary, processed sensor data at the bottle opening depths. Four sites of interest were surveyed: Orphan Knoll off the coast of Newfoundland, and Nuuk, Nasrsaq, and Cape Farewell off southwest Greenland. Description of the data available is given in the Data Documentation file (see Further details).
    Keywords: ICY-LAB; Isotope CYcling in the LABrador Sea
    Type: dataset publication series
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 8
    facet.materialart.
    Unknown
    Stable silicon isotope ratios of sponge spicules and updated age model from core OMEXII-9K (2018)
    PANGAEA
    In:  Supplement to: Hendry, Katharine R; Gong, Xun; Knorr, Gregor; Pike, Jennifer; Hall, Ian R (2016): Deglacial diatom production in the tropical North Atlantic driven by enhanced silicic acid supply. Earth and Planetary Science Letters, 438, 122-129, https://doi.org/10.1016/j.epsl.2016.01.016
    Details
    Publication Date: 2024-07-19
    Description: This data release contains stable silicon isotope data from sponge spicules isolated from sediment core OMEXII-9K off the Iberian Margin, from 0 to 336cm, and an updated age model.
    Keywords: OMEXII-9K_2; Tropical North Atlantic
    Type: dataset publication series
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 9
    facet.materialart.
    Unknown
    Geochemistry of tropical Atlantic sediments of Marine Isotope Stage 4 (2013)
    PANGAEA
    In:  Supplement to: Griffiths, James D; Barker, Stephen; Hendry, Katharine R; Thornalley, David J R; van de Flierdt, Tina; Hall, Ian R; Anderson, Robert F (2013): Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4. Paleoceanography, 28(2), 307-318, https://doi.org/10.1002/palo.20030
    Details
    Publication Date: 2024-07-19
    Description: Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are the main conduits for the supply of dissolved silicon (silicic acid) from the deep Southern Ocean (SO) to the low-latitude surface ocean and therefore have an important control on low-latitude diatom productivity. Enhanced supply of silicic acid by AAIW (and SAMW) during glacial periods may have enabled tropical diatoms to outcompete carbonate-producing phytoplankton, decreasing the relative export of inorganic to organic carbon to the deep ocean and lowering atmospheric pCO2. This mechanism is known as the "silicic acid leakage hypothesis" (SALH). Here we present records of neodymium and silicon isotopes from the western tropical Atlantic that provide the first direct evidence of increased silicic acid leakage from the Southern Ocean to the tropical Atlantic within AAIW during glacial Marine Isotope Stage 4 (~60-70 ka). This leakage was approximately coeval with enhanced diatom export in the NW Atlantic and across the eastern equatorial Atlantic and provides support for the SALH as a contributor to CO2 drawdown during full glacial development.
    Type: dataset publication series
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 10
    facet.materialart.
    Unknown
    Opal chemistry of costal Antarctic sediments (2008)
    PANGAEA
    In:  Supplement to: Hendry, Katharine R; Rickaby, Rosalind E M (2008): Opal (Zn/Si) ratios as a nearshore geochemical proxy in coastal Antarctica. Paleoceanography, 23(2), PA2218, https://doi.org/10.1029/2007PA001576
    Details
    Publication Date: 2024-07-19
    Description: During the last 50 years, the Antarctic Peninsula has experienced rapid warming with associated retreat of 87% of marine and tidewater glacier fronts. Accelerated glacial retreat and iceberg calving may have a significant impact on the freshwater and nutrient supply to the phytoplankton communities of the highly productive coastal regions. However, commonly used biogenic carbonate proxies for nutrient and salinity conditions are not preserved in sediments from coastal Antarctica. Here we describe a method for the measurement of zinc to silicon ratios in diatom opal, (Zn/Si)opal, which is a potential archive in Antarctic marine sediments. A core top calibration from the West Antarctic Peninsula shows (Zn/Si)opal is a proxy for mixed layer salinity. We present down-core (Zn/Si)opal paleosalinity records from two rapidly accumulating sites taken from nearshore environments off the West Antarctic Peninsula which show an increase in meltwater input in recent decades. Our records show that the recent melting in this region is unprecedented for over 120 years.
    Type: dataset publication series
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...