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  • Articles  (7)
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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 208-208 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - In the Commentary by E. Nisbet and C. M. R. Fowler on 29 June 1995 (ref. 1) and in your Opinion piece in the same issue2, the significance of Brent Spar's cargo is measured by the yardstick of the discharge rate of metals by a natural system: the Broken Spur vent field on the Mid-Atlantic ...
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2016-06-07
    Description: Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, and potential for its release to the atmosphere. We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane. If methane fluxes increase then a greater proportion of methane will be transported by advection or in the gas phase, which reduces the efficiency of the methanotrophic sink. Higher freshwater discharge to Arctic shelf seas may increase stratification and inhibit transfer of methane gas to surface waters, although there is some evidence that increased stratification may lead to warming of sub-pycnocline waters, increasing the potential for hydrate dissociation. Loss of sea-ice is likely to increase wind speeds and sea-air exchange of methane will consequently increase. Studies of the distribution and cycling of methane beneath and within sea ice are limited, but it seems likely that the sea-air methane flux is higher during melting in seasonally ice-covered regions. Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages and feedback pathways between climate warming and release of methane from marine sediments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 3
    Publication Date: 2015-12-15
    Description: Large amounts of the greenhouse gas methane are released from the seabed but liberation of methane to the atmosphere is mitigated by aerobic methanotrophs in the water column. The size and activity of methanotrophic communities are thought to be mainly determined by nutrient and redox dynamics, but little is known about the effects of water mass transport. Here, we show that cold bottom waters at methane seeps west off Svalbard, which contained a large number of aerobic methanotrophs, were rapidly displaced by warmer waters with a considerably smaller methanotrophic community. This water mass exchange, caused by short-term variations of the West Spitsbergen Current strongly reduced methanotrophic activity. Currents are common at many methane seeps and could thus be a globally important control on methane oxidation in the water column.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
    Publication Date: 2022-05-25
    Description: © The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS Biology 10 (2012): e1001234, doi:10.1371/journal.pbio.1001234.
    Description: Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than previously recognised.
    Description: The ChEsSo research programme was funded by a NERC Consortium Grant (NE/DO1249X/1) and supported by the Census of Marine Life and the Sloan Foundation, and the Total Foundation for Biodiversity (Abyss 2100)(SVTH) all of which are gratefully acknowledged. We also acknowledge NSF grant ANT-0739675 (CG and TS), NERC PhD studentships NE/D01429X/1(LH, LM, CNR), NE/H524922/1(JH) and NE/F010664/1 (WDKR), a Cusanuswerk doctoral fellowship, and a Lesley & Charles Hilton-Brown Scholarship, University of St. Andrews (PHBS).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2021-12-15
    Description: Carbon capture and storage (CCS) is a key technology to reduce carbon dioxide (CO2) emissions from industrial processes in a feasible, substantial, and timely manner. For geological CO2 storage to be safe, reliable, and accepted by society, robust strategies for CO2 leakage detection, quantification and management are crucial. The STEMM-CCS (Strategies for Environmental Monitoring of Marine Carbon Capture and Storage) project aimed to provide techniques and understanding to enable and inform cost-effective monitoring of CCS sites in the marine environment. A controlled CO2 release experiment was carried out in the central North Sea, designed to mimic an unintended emission of CO2 from a subsurface CO2 storage site to the seafloor. A total of 675 kg of CO2 were released into the shallow sediments (~3 m below seafloor), at flow rates between 6 and 143 kg/d. A combination of novel techniques, adapted versions of existing techniques, and well-proven standard techniques were used to detect, characterise and quantify gaseous and dissolved CO2 in the sediments and the overlying seawater. This paper provides an overview of this ambitious field experiment. We describe the preparatory work prior to the release experiment, the experimental layout and procedures, the methods tested, and summarise the main results and the lessons learnt.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 6
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geochimica et Cosmochimica Acta 139 (2014): 47-71, doi:10.1016/j.gca.2014.04.024.
    Description: The East Scotia Ridge is an active back-arc spreading centre located to the west of the South Sandwich island arc in the Southern Ocean. Initial exploration of the ridge by deep-tow surveys provided the first evidence for hydrothermal activity in a back-arc setting outside of the western Pacific, and we returned in 2010 with a remotely operated vehicle to precisely locate and sample hydrothermal sites along ridge segments E2 and E9. Here we report the chemical and isotopic composition of high- and low-temperature vent fluids, and the mineralogy of associated high-temperature chimney material, for two sites at E2 (Dog’s Head and Sepia), and four sites at E9 (Black & White, Ivory Tower, Pagoda and Launch Pad). The chemistry of the fluids is highly variable between the ridge segments. Fluid temperatures were ∼350 °C at all vent sites except Black & White, which was significantly hotter (383 °C). End-member chloride concentrations in E2 fluids (532–536 mM) were close to background seawater (540 mM), whereas Cl in E9 fluids was much lower (98–220 mM) indicating that these fluids are affected by phase separation. Concentrations of the alkali elements (Na, Li, K and Cs) and the alkaline earth elements (Ca, Sr and Ba) co-vary with Cl, due to charge balance constraints. Similarly, concentrations of Mn and Zn are highest in the high Cl fluids but, by contrast, Fe/Cl ratios are higher in E9 fluids (3.8–8.1 × 10−3) than they are in E2 fluids (1.5–2.4 × 10−3) and fluids with lowest Cl have highest Cu. Although both ridge segments are magmatically inflated, there is no compelling evidence for input of magmatic gases to the vent fluids. Fluid δD values range from 0.2‰ to 1.5‰, pH values (3.02–3.42) are not especially low, and F concentrations (34.6–54.4 μM) are lower than bottom seawater (62.8 μM). The uppermost sections of conjugate chimney material from E2, and from Ivory Tower and Pagoda at E9, typically exhibit inner zones of massive chalcopyrite enclosed within an outer zone of disseminated sulphide, principally sphalerite and pyrite, in an anhydrite matrix. By contrast, the innermost part of the chimneys that currently vent fluids with lowest Cl (Black & White and Launch Pad), is dominated by anhydrite. By defining and assessing the controls on the chemical composition of these vent fluids, and associated mineralisation, this study provides new information for evaluating the significance of hydrothermal processes at back-arc basins for ocean chemistry and the formation of seafloor mineral deposits.
    Description: This work was funded by the Natural Environment Research Council consortium grant NE/D01249X/1. C.R.G. acknowledges further support from the National Science Foundation’s Office of Polar Programs grant ANT-0739675. N.R.B. acknowledges funding from the National Sciences and Engineering Research Council of Canada, Ontario Ministry of Research and Innovation, and the Academic Development Fund at Western University.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
    Publication Date: 2018-03-16
    Description: High transplant-related mortality associated with haematopoietic stem cell transplantation for paediatric therapy-related acute myeloid leukaemia (t-AML). A study on behalf of the United Kingdom Paediatric Blood and Bone Marrow Transplant Group High transplant-related mortality associated with haematopoietic stem cell transplantation for paediatric therapy-related acute myeloid leukaemia (t-AML). A study on behalf of the United Kingdom Paediatric Blood and Bone Marrow Transplant Group, Published online: 15 March 2018; doi:10.1038/s41409-018-0157-x High transplant-related mortality associated with haematopoietic stem cell transplantation for paediatric therapy-related acute myeloid leukaemia (t-AML). A study on behalf of the United Kingdom Paediatric Blood and Bone Marrow Transplant Group
    Print ISSN: 0268-3369
    Electronic ISSN: 1476-5365
    Topics: Medicine
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  • 8
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    PANGAEA
    In:  Supplement to: Steinle, Lea; Graves, Carolyn; Treude, Tina; Ferre, Benedicte; Biastoch, Arne; Bussmann, Ingeborg; Berndt, Christian; Krastel, Sebastian; James, Rachael H; Behrens, Erik; Böning, Claus W; Greinert, Jens; Sapart, Célia-Julia; Scheinert, Markus; Sommer, Stefan; Lehmann, Moritz F; Niemann, Helge (2015): Water column methanotrophy controlled by a rapid oceanographic switch. Nature Geoscience, 8(5), 378–382, https://doi.org/10.1038/ngeo2420
    Publication Date: 2023-03-03
    Description: Large amounts of the greenhouse gas methane are released from the seabed to the water column where it may be consumed by aerobic methanotrophic bacteria. This microbial filter is consequently the last marine sink for methane before its liberation to the atmosphere. The size and activity of methanotrophic communities, which determine the capacity of the water column methane filter, are thought to be mainly controlled by nutrient and redox dynamics, but little is known about the effects of ocean currents. Here, we report measurements of methanotrophic activity and biomass (CARD-FISH) at methane seeps west of Svalbard, and related them to physical water mass properties (CTD) and modelled current dynamics. We show that cold bottom water containing a large number of aerobic methanotrophs was rapidly displaced by warmer water with a considerably smaller methanotrophic community. This water mass exchange, caused by short-term variations of the West Spitsbergen Current, constitutes a rapid oceanographic switch severely reducing methanotrophic activity in the water column. Strong and fluctuating currents are widespread oceanographic features common at many methane seep systems and are thus likely to globally affect methane oxidation in the ocean water column.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 9
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    PANGAEA
    In:  Supplement to: Hathorne, Ed C; Felis, Thomas; James, Rachael H; Thomas, Alexander L (2011): Laser ablation ICP-MS screening of corals for diagenetically affected areas applied to Tahiti corals from the last deglaciation. Geochimica et Cosmochimica Acta, 75, 1490-1506, https://doi.org/10.1016/j.gca.2010.12.011
    Publication Date: 2023-06-27
    Description: Fossil corals are unique archives of past seasonal climate variability, providing vital information about seasonal climate phenomena such as ENSO and monsoons. However, submarine diagenetic processes can potentially obscure the original climate signals and lead to false interpretations. Here we demonstrate the potential of laser ablation ICP-MS to rapidly detect secondary aragonite precipitates in fossil Porites colonies recovered by Integrated Ocean Drilling Program (IODP) Expedition 310 from submerged deglacial reefs off Tahiti. High resolution (100 µm) measurements of coralline B/Ca, Mg/Ca, S/Ca, and U/Ca ratios are used to distinguish areas of pristine skeleton from those afflicted with secondary aragonite. Measurements of coralline Sr/Ca, U/Ca and oxygen isotope ratios, from areas identified as pristine, reveal that the seasonal range of sea surface temperature in the tropical south Pacific during the last deglaciation (14.7 and 11 ka) was similar to that of today.
    Keywords: 310-M0007B; 310-M0025B; Boron/Calcium ratio; DISTANCE; DP Hunter; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Exp310; Inductively coupled plasma - mass spectrometry (ICP-MS); Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP; Magnesium/Calcium ratio; Manganese/Calcium ratio; Mass spectrometry; Sample code/label; Sample code/label 2; Strontium/Calcium ratio; TAH-02A-5H; TAH-03A-3A; Tahiti, offshore Maraa; Tahiti, offshore Tiarei; Tahiti Sea Level; Uranium/Calcium ratio; δ13C, skeletal carbonate; δ18O, skeletal carbonate
    Type: Dataset
    Format: text/tab-separated-values, 1038 data points
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  • 10
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    PANGAEA
    In:  Supplement to: Decitre, Sylvie; Buatier, Martine D; James, Rachael H (2004): Li and Li isotopic composition of hydrothermally altered sediments at Middle Valley, Juan De Fuca. Chemical Geology, 211(3-4), 363-373, https://doi.org/10.1016/j.chemgeo.2004.07.005
    Publication Date: 2024-01-09
    Description: Li and Li isotopes have been measured in the clay fraction of sediments recovered from the Middle Valley hydrothermal site on the Juan De Fuca Ridge. The Li content of pure detrital clays is 51 ppm while hydrothermal clays and carbonates have lower Li (22+/-11 ppm). However, there is no clear relationship between the mineralogy of the hydrothermal alteration products and their Li content. The d7Li value of the detrital clays is +5.8‰. Hydrothermal clays and carbonates have d7Li in the range of -3.9‰ to +7.8‰; these values do not seem to be dependent on the temperature at which they formed. Modelling of the Li and Li isotope systematics indicates that the fluid from which the alteration products form is significantly enriched in Li (higher than 10000 µmol/kg) relative to pore fluids recovered from within the sediments (up to 589 µmol/kg; [Wheat, C.G., M.J. Mottl, 1994. Data report: trace metal composition of pore water from Sites 855 through 858, Middle valley, Juan De Fuca Ridge. In Mottl, M.J., Davis, E.E., Fisher, A.T., Slack, J.F. (Eds.), Proc. ODP, Sci. Res. 139: 749–755; doi:10.2973/odp.proc.sr.139.269.1994]), and that this Li is derived from sediment. Thus, the alteration products are not in equilibrium with their conjugate pore fluids; rather, the alteration minerals formed at lower water/sediment ratios. This suggests that fluid flow pathways at Middle Valley were more diffuse in the past than they are today.
    Keywords: 139-858A; 139-858B; DRILL; Drilling/drill rig; Joides Resolution; Leg139; North Pacific Ocean; Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 4 datasets
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