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  • PANGAEA  (3)
  • Wiley  (2)
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  • 1
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    Unknown
    Geochemistry of sediment cores and hydrochemistry of water bottle samples in the North Sea during James Cook cruise JC077 (2017)
    PANGAEA
    In:  Supplement to: Lichtschlag, Anna; Cevatoglu, Melis; Connelly, Douglas P; James, Rachael H; Bull, Jonathan M (2018): Increased Fluid Flow Activity in Shallow Sediments at the 3 km Long Hugin Fracture in the Central North Sea. Geochemistry, Geophysics, Geosystems, 19(1), 2-20, https://doi.org/10.1002/2017GC007181
    Details
    Publication Date: 2023-02-24
    Description: The North Sea hosts a wide variety of seafloor seeps that may be important for transfer of chemical species, such as methane, from the Earth's interior to its exterior. Here we provide geochemical and geophysical evidence for fluid flow within shallow sediments at the recently discovered, 3 -km long Hugin Fracture in the Central North Sea. Although venting of gas bubbles was not observed, concentrations of dissolved methane were significantly elevated (up to six-times background values) in the water column at various locations above the fracture, and microbial mats that form in the presence of methane were observed at the seafloor. Seismic amplitude anomalies revealed a bright spot at a fault bend that may be the source of the water column methane. Sediment porewaters recovered in close proximity to the Hugin Fracture indicate the presence of fluids from two different shallow (〈500 m) sources: (i) a reduced fluid characterized by elevated methane concentrations and/or high levels of dissolved sulfide (up to 6 mmol L-1), and (ii) a low-chlorinity fluid (Cl ~305 mmol L-1) that has low levels of dissolved methane and/or sulfide. The area of the seafloor affected by the presence of methane-enriched fluids is similar to the footprint of seepage from other morphological features in the North Sea.
    Keywords: ECO2; Sub-seabed CO2 Storage: Impact on Marine Ecosystems
    Type: Dataset
    Format: application/zip, 25 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Hydrochemistry measured on water bottle samples during James Cook cruise JC077 (2015)
    PANGAEA
    Details
    Publication Date: 2023-02-24
    Keywords: AA; Alkalinity, total; Autoanalyzer; Carbon, inorganic, dissolved; Cast number; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; ECO2; Elevation of event; Event label; Gas chromatography; James Cook; JC077; JC077-CTD1; JC077-CTD10; JC077-CTD11; JC077-CTD12; JC077-CTD13; JC077-CTD14; JC077-CTD15; JC077-CTD16; JC077-CTD17; JC077-CTD18; JC077-CTD19; JC077-CTD2; JC077-CTD20; JC077-CTD21; JC077-CTD22; JC077-CTD23; JC077-CTD24; JC077-CTD25; JC077-CTD26; JC077-CTD27; JC077-CTD28; JC077-CTD29; JC077-CTD3; JC077-CTD30; JC077-CTD31; JC077-CTD32; JC077-CTD33; JC077-CTD34; JC077-CTD35; JC077-CTD36; JC077-CTD37; JC077-CTD38; JC077-CTD39; JC077-CTD4; JC077-CTD40; JC077-CTD41; JC077-CTD42; JC077-CTD43; JC077-CTD44; JC077-CTD45; JC077-CTD46; JC077-CTD47; JC077-CTD48; JC077-CTD49; JC077-CTD5; JC077-CTD50; JC077-CTD51; JC077-CTD52; JC077-CTD53; JC077-CTD54; JC077-CTD55; JC077-CTD56; JC077-CTD57; JC077-CTD58; JC077-CTD59; JC077-CTD6; JC077-CTD60; JC077-CTD61; JC077-CTD62; JC077-CTD63; JC077-CTD64; JC077-CTD7; JC077-CTD8; JC077-CTD9; Latitude of event; Longitude of event; Methane; Nitrate and Nitrite; Oxygen; Phosphate; Silicate; Sub-seabed CO2 Storage: Impact on Marine Ecosystems; Titration; Titration, Winkler
    Type: Dataset
    Format: text/tab-separated-values, 1874 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 3
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    Deep-Ocean dissolved organic matter in hydrothermal vents (2015)
    PANGAEA
    In:  Supplement to: Hawkes, Jeffrey A; Rossel, Pamela E; Stubbins, Aron; Butterfield, David A; Connelly, Douglas P; Achterberg, Eric Pieter; Koschinsky, Andrea; Chavagnac, Valerie; Hansen, Christian T; Bach, Wolfgang; Dittmar, Thorsten (2015): Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation. Nature Geoscience, 8(11), 856-860, https://doi.org/10.1038/ngeo2543
    Details
    Publication Date: 2024-02-17
    Description: Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood (Dittmar and Stubbins, 2014; Hansell, 2013, doi:10.1146/annurev-marine-120710-100757). Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years (Elderfield and Schultz, 1996, doi:10.1146/annurev.earth.24.1.191).
    Keywords: Akademik Mstislav Keldysh; AMK47; AMK47-Lost_City; AT18-08; Atlantis (1997); Carbon, organic, dissolved; Carbon, organic, dissolved, extracted; Comment; Comment 2 (continued); Contamination; CTD/Rosette; CTD-RO; Description; Error; Event label; Factor; Identification; ISIS; ISIS MS2000; J2-574; J2-575; J2-576; J2-579; J2-580; J2-581; J2-583; James Cook; JC042; JC080; JC082; JC42_ISIS_130; JC42_ISIS_133; JC42_ISIS_134; JC42_ISIS_141; JC80_015_CTD; JC80_ISIS_189; JC80_ISIS_190; JC80_ISIS_194; JC82_ISIS_198; JC82_ISIS_200; JC82_ISIS_202; JC82_ISIS_204; JC82_ISIS_206; JC82_ISIS_207; Juan_de_Fuca_Ridge_Axial; Juan_de_Fuca_Ridge_Endeavour; Latitude of event; Lithology/composition/facies; Longitude of event; Lost City Hydrothermal Field, Mid-Atlantic Ridge; M82/3; M82/3_719-1; M82/3_722-1; M82/3_739-1; M82/3_756-1; Magnesium; Maria S. Merian; Meteor (1986); MIR; MIR deep-sea manned submersible; MSM10/3; MSM10/3_290ROV-11; MSM10/3_300; MSM10/3_313ROV-12; Name; Ocean and sea region; Percentage; Precision; Remote operated vehicle; Remote operated vehicle Jason II; ROV; ROVJ; Sample type; Sample volume; Sampling date; Site; Solid phase extractable; South Atlantic Ocean; tropical/subtropical North Atlantic; Type; Volume; Wakamiko_Crater
    Type: Dataset
    Format: text/tab-separated-values, 4130 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 4
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    The importance of shallow hydrothermal island arc systems in ocean biogeochemistry (2014)
    AGU (American Geophysical Union) | Wiley
    In:  Geophysical Research Letters, 41 (3). pp. 942-947.
    Details
    Publication Date: 2021-04-23
    Description: Hydrothermal venting often occurs at submarine volcanic calderas on island arc chains, typically at shallower depths than mid–ocean ridges. The effect of these systems on ocean biogeochemistry has been under-investigated to date. Here we show that hydrothermal effluent from an island arc caldera was rich in Fe(III) colloids (0.02–0.2 µm; 46% of total Fe), contributing to a fraction of hydrothermal Fe that was stable in ocean water. Iron(III) colloids from island arc calderas may be transferred into surrounding waters (generally 0–1500 m depth) by ocean currents, thereby potentially stimulating surface ocean primary productivity. Hydrothermal Fe oxyhydroxide particles (〉0.2 µm) were also pervasive in the studied caldera and contained high concentrations of oxyanions of phosphorus (P), vanadium (V), arsenic (As), and manganese (Mn). Hydrothermal island arcs may be responsible for 〉 50% of global hydrothermal P scavenging and 〉 40% V scavenging, despite representing 〈10% of global hydrothermal fluid flow.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2013GL058817
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard (2015)
    AGU (American Geophysical Union) | Wiley
    In:  Journal of Geophysical Research: Oceans, 120 (9). pp. 6185-6201.
    Details
    Publication Date: 2017-05-02
    Description: Widespread seepage of methane from seafloor sediments offshore Svalbard close to the landward limit of the gas hydrate stability zone (GHSZ) may, in part, be driven by hydrate destabilization due to bottom water warming. To assess whether this methane reaches the atmosphere where it may contribute to further warming, we have undertaken comprehensive surveys of methane in seawater and air on the upper slope and shelf region. Near the GHSZ limit at ∼400 m water depth, methane concentrations are highest close to the seabed, reaching 825 nM. A simple box model of dissolved methane removal from bottom waters by horizontal and vertical mixing and microbially mediated oxidation indicates that ∼60% of methane released at the seafloor is oxidized at depth before it mixes with overlying surface waters. Deep waters are therefore not a significant source of methane to intermediate and surface waters; rather, relatively high methane concentrations in these waters (up to 50 nM) are attributed to isopycnal turbulent mixing with shelf waters. On the shelf, extensive seafloor seepage at 〈100 m water depth produces methane concentrations of up to 615 nM. The diffusive flux of methane from sea to air in the vicinity of the landward limit of the GHSZ is ∼4-20 μmol m-2 d-1, which is small relative to other Arctic sources. In support of this, analyses of mole fractions and the carbon isotope signature of atmospheric methane above the seeps do not indicate a significant local contribution from the seafloor source.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2015JC011084
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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