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  • 1
    Electronic Resource
    Electronic Resource
    Ethylene and methane in the upper water column of the subtropical Atlantic (1999)
    Springer
    Biogeochemistry 44 (1999), S. 73-91 
    Details
    ISSN: 1573-515X
    Keywords: Atlantic ; ethylene ; methane ; sea-air exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The vertical distributions of ethylene and methane in the upper water column of the subtropical Atlantic were measured along a transect from Madeira to the Caribbean and compared with temperature, salinity, oxygen, nutrients, chlorophyll-a, and dissolved organic carbon (DOC). Methane concentrations between 41.6 and 60.7 nL L-1 were found in the upper 20 m of the water column giving a calculated average flux of methane into the atmosphere of 0.82 μg m-2 h-1. Methane profiles reveal several distinct maxima in the upper 500 m of the water column and short-time variations which are presumably partly related to the vertical migration of zooplankton. Ethylene concentrations in near surface waters varied in the range of 1.8 to 8.2 nL L-1. Calculated flux rates for ethylene into the atmosphere were in the range of 0.41 to 1.35 μg m-2 h-1 with a mean of 0.83 μg m-2 h-1. Maximum concentrations of up to 39.2 nL L-1 were detected directly below the pycnocline in the western Atlantic. The vertical distributions of ethylene generally showed one maximum at the pycnocline (about 100 m depth) where elevated concentrations of chlorophyll-a, dissolved oxygen, and nutrients were also found; no ethylene was detected below 270 m depth. This suggests that ethylene release is mainly related to one, probably phytoplankton associated, source, while for methane, enhanced net production occurs at various depth horizons. For surface waters, a simple correlation between ethylene and chlorophyll-a or DOC concentrations could not be observed. No considerable diurnal variation was observed for the distribution and concentration of ethylene in the upper water column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006090917059
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ethylene and methane in the upper water column of the subtropical Atlantic (1999)
    Springer
    Biogeochemistry 44 (1999), S. 73-91 
    Details
    ISSN: 1573-515X
    Keywords: Atlantic ; ethylene ; methane ; sea-air exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The vertical distributions of ethylene and methane in the upper water column of the subtropical Atlantic were measured along a transect from Madeira to the Caribbean and compared with temperature, salinity, oxygen, nutrients, chlorophyll-a, and dissolved organic carbon (DOC). Methane concentrations between 41.6 and 60.7 nL L−1 were found in the upper 20 m of the water column giving a calculated average flux of methane into the atmosphere of 0.82μg m−2 h−1. Methane profiles reveal several distinct maxima in the upper 500 m of the water column and short-time variations which are presumably partly related to the vertical migration of Zooplankton. Ethylene concentrations in near surface waters varied in the range of 1.8 to 8.2 nL L−1. Calculated flux rates for ethylene into the atmosphere were in the range of 0.41 to 1.35μg m−2 h−1 with a mean of 0.83μg m−2h−2. Maximum concentrations of up to 39.2 nL L−2 were detected directly below the pycnocline in the western Atlantic. The vertical distributions of ethylene generally showed one maximum at the pycnocline (about 100 m depth) where elevated concentrations of chlorophyll-a, dissolved oxygen, and nutrients were also found; no ethylene was detected below 270 m depth. This suggests that ethylene release is mainly related to one, probably phytoplankton associated, source, while for methane, enhanced net production occurs at various depth horizons. For surface waters, a simple correlation between ethylene and chlorophyll-a or DOC concentrations could not be observed. No considerable diurnal variation was observed for the distribution and concentration of ethylene in the upper water column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00992999
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    Paper (German National Licenses)
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  • 3
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    Deglacial to Holocene variability in surface water characteristics and major floods in the Beaufort Sea (2020)
    Springer
    In:  EPIC3Communications Earth & Environment, Springer, 1(25), pp. 1-12
    Details
    Publication Date: 2020-10-15
    Description: Surface water characteristics of the Beaufort Sea have global climate implications during the last deglaciation and the Holocene, as (1) sea ice is a critical component of the climate system and (2) Laurentide Ice Sheet meltwater discharges via the Mackenzie River to the Arctic Ocean and further, to its outflow near the deep-water source area of the Atlantic Meridional Overturning Circulation. Here we present high-resolution biomarker records from the southern Beaufort Sea. Multi-proxy biomarker reconstruction suggests that the southern Beaufort Sea was nearly ice-free during the deglacial to Holocene transition, and a seasonal sea-ice cover developed during the mid-late Holocene. Superimposed on the long-term change, two events of high sediment flux were documented at ca. 13 and 11 kyr BP, respectively. The first event can be attributed to the Younger Dryas flood and the second event is likely related to a second flood and/or coastal erosion.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Warming of surface waters in the mid-latitude North Atlantic during Heinrich events (2013)
    AMER GEOPHYSICAL UNION
    In:  EPIC3Paleoceanography, AMER GEOPHYSICAL UNION, 28(1), pp. 153-163, ISSN: 0883-8305
    Details
    Publication Date: 2019-07-16
    Description: During the six Heinrich events of the last 70 kyr, episodic calving from the circum-Atlantic ice sheets released large numbers of icebergs into the North Atlantic. These icebergs and associated meltwater flux are hypothesized to have led to a shutdown of Atlantic Meridional Overturning Circulation and severe cooling in large parts of the Northern Hemisphere. However, due to the limited availability of high-resolution records, the magnitude of sea surface temperature (SST) changes related to the impact of Heinrich events on the midlatitude North Atlantic is poorly constrained. Here we present a record of U37K′-based SSTs derived from sediments of Integrated Ocean Drilling Project Site U1313, located at the southern end of the ice-rafted debris (IRD) belt in the midlatitude North Atlantic (41°N). We demonstrate that all six Heinrich events are associated with a rapid warming of surface waters by 2–4°C in a few thousand years. The presence of IRD leaves no doubt about the simultaneous timing and correlation between rapid surface water warming and Heinrich events. We argue that this warming in the midlatitude North Atlantic is related to a northward expansion of the subtropical gyre during Heinrich events. As a wide range of studies demonstrated that in the central IRD belt Heinrich events are associated with low SSTs, these results thus identify an antiphased (seesaw) pattern in SSTs during Heinrich events between the midlatitude (warm) and northern North Atlantic (cold). This highlights the complex response of surface water characteristics in the North Atlantic to Heinrich events that is poorly reproduced by freshwater hosing experiments and challenges the widely accepted view that, within the IRD belt of the North Atlantic, Heinrich events coincide with periods of low SSTs.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Lipid biomarkers in surface sediments from the gulf of genoa, Ligurian sea (NW Mediterranean sea) and their potential for the reconstruction of palaeo-environments (2014)
    Pergamon-Elsevier
    In:  EPIC3Deep Sea Research Part I: Oceanographic Research Papers, Pergamon-Elsevier, 89, pp. 68-83, ISSN: 0967-0637
    Details
    Publication Date: 2014-06-23
    Description: A series of molecular organic markers were determined in surface sediments from the Gulf of Genoa (Ligurian Sea) in order to evaluate their potential for palaeo-environmental reconstructions. Allochthonous input can be characterized by the distributions of n-C29 and n-C31 alkanes, n-C26 and n-C28 alkanols and branched glycerol dialkyl glycerol tetraethers (GDGTs), whose concentrations are generally highest near the river mouths. In the open basin however, terrestrial n-alkanes and n-alkanols may have an additional, eolian source. Autochthonous input is represented by crenarchaeol and isoprenoid GDGTs. Their concentrations are highest in the open basin showing the preference of Thaumarchaeota for oligotrophic waters. Indications of a significant degradation of sterols and C37 alkenones exclude these lipids as reliable productivity proxies. Using terrestrial and aquatic lipids as end-members allows estimating the percentage of terrestrial organic matter between 20% and 58% in the coastal area decreasing to 1–30% in the deep basin. The spatial distribution of sea surface temperature (SST) estimates using the alkenone-based UK′37 index is very similar to the autumnal (November) mean satellite-based SST distribution. Conversely, TEXH86-derived SST estimates are close to winter SSTs in the coastal area and summer SSTs in the open basin. This pattern reflects presumably a shift in the main production of Thaumarchaeota from the coastal area in winter to the open basin in summer. This study represents a major prerequisite for the future application of lipid biomarkers on sediment cores from the Gulf of Genoa.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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