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  • 1
    Electronic Resource
    Electronic Resource
    Improved electronic control unit for a motor type beam scanner
    Amsterdam : Elsevier
    Nuclear Instruments and Methods 93 (1971), S. 391-393 
    Details
    ISSN: 0029-554X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0029-554X(71)90498-8
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Description of a Mossbauer spectrometer using a piezoelectric bar
    Amsterdam : Elsevier
    Nuclear Instruments and Methods 81 (1970), S. 211-213 
    Details
    ISSN: 0029-554X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0029-554X(70)90636-1
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Microbial activity in sandy and muddy estuarine sediments (1991)
    Springer
    Geo-marine letters 11 (1991), S. 194-198 
    Details
    ISSN: 1432-1157
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Striking differences were observed in the use of the electron acceptors involved in the degradation of organic matter by heterotrophic bacterial activity between a muddy and a sandy sediment on the same tidal flat of the Scheldt estuary. These bio-reduction reactions could have a quite different effect on the cycling of trace metals in the sediment as suggested by the results of the mobilization experiments. Trace metal speciation can be described as a function of the redox potential, in view of the fact that the latter is related to the heterotrophic bacterial activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431012
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Geochemical processes in muddy and sandy tidal flat sediments (1991)
    Springer
    Geo-marine letters 11 (1991), S. 188-193 
    Details
    ISSN: 1432-1157
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Different approaches, such as element analyses of the bulk sediment and of the fine sediment fraction (〈63 μm), sequential extraction techniques, correlation coefficient, and enrichment factor calculations, clearly demonstrate the differences in geochemical behavior of a muddy and a sandy sediment on the same tidal flat in the Scheldt estuary (Belgium). The geochemical processes in combination with the relatively large transport mobility of dissolved compounds due to the tidal action in the sediment, created compound specific vertical distribution profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431011
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Geochemistry of mercury in an intertidal flat of the Scheldt estuary (1993)
    Springer
    Aquatic ecology 27 (1993), S. 267-277 
    Details
    ISSN: 1573-5125
    Keywords: Estuarine sediments ; mercury ; methylmercury ; methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sediments were sampled on the ‘Groot Buitenschoor’, an intertidal flat located at about 60 km from the Scheldt's river mouth. Hg concentrations ranged from 30 to 1756 ng g−1. The concentrations were strongly correlated with fine grain fraction, organic matter content and sulphide concentrations. Incubation experiments were performed in order to determine the potential methylation rate of Hg as well as biotic and abiotic factors influencing this transformation. About 1 to 2% of the added inorganic Hg is converted into methylmercury. This conversion rate points to the same equilibrium ratio as was observed in natural sediments, indicating an equilibrium between methylation and demethylation reactions in the sediments. Incubation of a sterilised sediment sample significantly decreased the methylation rate, but the methylmercury concentrations observed are still ten times higher than the natural (unspiked) sediment. This result could be due to a chemical (non-enzymatic) methylation of mercury. Sulphate reducing bacteria are the main species responsible for the methylation of Hg at this site. Addition of Na2MoO4, a specific inhibitor of sulphate reducing bacteria, decreased the methylation rate to the abiotic level (sterilised sediment). High sulphate reduction rates, however, lead to lower methylation rates. Increased formation of sulphides due to microbial sulphate reduction leads to enhanced HgS formation and this reaction competes with the methylation process. HgS is in fact the major product formed by the reaction of sulphate reducing bacteria with Hg species. About 50% of the Hg spiked to the sediments is transformed into HgS during the incubation experiments, and that compound is practically unavailable for methylation in contrast to other bound forms of Hg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02334790
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The behaviour of copper and zinc in the Scheldt estuary (1993)
    Springer
    Aquatic ecology 27 (1993), S. 279-286 
    Details
    ISSN: 1573-5125
    Keywords: particulate and dissolved Cu and Zn ; Scheldt estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The behaviour of copper and zinc in the Scheldt estuary, both in the particulate and the dissolved phase, is discussed for the period 1982–1983. The longitudinal particulate copper and zinc profiles fall below the dilution line, which is attributed to mixing and mobilization processes. In the dissolved phase both metals show a production region in the end member of the estuary, for copper a pronounced mid estuarine maximum is observed. Study of the metal speciation suggested that organic ligands might keep heavy metals in solution, especially in area of intensive production, and promote the subsequent export of these metals downstream the estuary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02334791
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    Paper (German National Licenses)
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  • 7
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    Export production in the Bay of Biscay as estimated from barium – barite in settling material: a comparison with new production (2000)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 47 (4). pp. 583-601.
    Details
    Publication Date: 2020-08-05
    Description: We present barium data for sediment traps deployed in a northeast Atlantic margin environment (Bay of Biscay). Fluxes of excess barium were measured with the objective of calculating carbon export production rates from the surface mixed layer and thus contribute to the understanding of organic carbon transport in a margin environment. Therefore, it was necessary to properly understand the different processes that affected the barium fluxes in this margin environment. Seasonal variability of POC/Ba flux ratios and decrease of barium solubilisation in the trap cups with increasing depth in the water column probably indicate that the efficiency of barite formation in the organic micro-environment varies with season and that the process is relatively slow and not yet completed in the upper 600 m of water column. Thus barite presence in biogenic aggregates will significantly depend on water column transit time of these aggregates. Furthermore, it was observed that significant lateral input of excess-Ba can occur, probably associated with residual currents leaving the margin. This advected excess-Ba affected especially the recorded fluxes in the deeper traps (〉1000 m) of the outer slope region. We have attempted to correct for this advected excess-Ba component, using Th (reported by others for the same samples) as an indicator of enhanced lateral flux and assigning a characteristic Ba/Th ratio to advected material. Using transfer functions relating excess-Ba flux with export production characteristic of margin areas, observed Ba fluxes indicate an export production between 7 and 18 g C m−2 yr−1. Such values are 3–7 times lower than estimates based on N-nutrient uptake and nutrient mass balances, but larger and more realistic than is obtained when a transfer function characteristic of open ocean systems is applied. The discrepancy between export production estimates based on excess-Ba fluxes and nutrient uptake could be resolved if part of the carbon is exported as dissolved organic matter. Results suggest that margin systems function differently from open ocean systems, and therefore Ba-proxy rationales developed for open ocean sites might not be applicable in margin areas.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0967-0637(99)00072-2
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Supply and demand of nutrients and dissolved organic matter at and across the NW European shelf break in relation to hydrography and biogeochemical activity (2001)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 48 (14-15) . pp. 3023-3047.
    Details
    Publication Date: 2020-08-05
    Description: As part of the OMEX I project, nutrient determinations were made on 17 cruises in the region of the Goban Spur and La Chapelle Bank between 46 and 51°N, in all seasons of the year, between 1993–1995. Over this period no change was detectable in the structure of the water masses below the deep winter mixed layer. The N : P (dissolved nitrate-to-phosphate) ratio changed from 16 at 100-m depth to less than 15 at 3300-m depth. At intermediate depths nutrient and oxygen data indicate the presence of Mediterranean Outflow water overlying Labrador Sea Water at its most eastern extension. Estimated maximum levels of production in the spring bloom are the total N-limited new primary production equivalent between 24 and 41 gC m−2, the equivalent maximum diatom production is 11 gC m−2. Measurements during the spring bloom suggest a conversion factor of 1 μM nitrate to 1 μg l−1 chlorophyll, at the shelf break, which is consistent with other recent measurements in European shelf seawaters. Sediment trap data suggest that 80% (5.4 g m−2) of the opal produced in the spring bloom dissolved before reaching the sediment trap at 600 m. A comparison of the winter and summer profiles for dissolved silicon suggests a similar dissolution of 9±3 g opal m−2 above 300-m depth. Measurements of dissolved organic carbon (DOC) in September 1994 show an enrichment of 7 μM-C above the seasonal thermocline relative to the winter values (52±4 μM). In winter dissolved organic nitrogen represents 40% of the pool of total dissolved nitrogen. There is no consistent evidence of an increase in the concentration of DON during summer. Measurements of nitrate in surface waters in January 1994 show that concentrations off-shelf vary with the temperature of the water and are related to the depth of winter mixing. Mixing in surface waters is discontinuous at the shelf break, demonstrating the degree to which exchange across the shelf break is limited even in winter. OMEX winter measurements of nitrate concentrations can be used to estimate the flow of water across the shelf break that would be required to maintain the nitrogen balance in the North Sea at a steady state. The estimate is 0.6 Sv (1 Sv=106 m3 s−1), which is similar to an earlier estimate of a total flow of 1.7 Sv based on salt budgets (cf. Huthnance, Deutsche Hydrographische Zeitschrift, 49 (1997) 153).
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0967-0645(01)00031-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Nitrogen uptake regime and phytoplankton community structure in the Atlantic and Indian sectors of the Southern Ocean (1998)
    In:  EPIC3J Mar Syst, 17, pp. 159-177
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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    PAPER (OA)
  • 10
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    Controls on Organic Carbon Export and Twilight Zone Remineralization (2008)
    In:  EPIC3Oceanography, 21, pp. 92-95
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
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