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Sample records for north sea chalk

  1. Dynamic and static elastic moduli of North Sea and deep sea chalk

    DEFF Research Database (Denmark)

    Gommesen, Lars; Fabricius, Ida Lykke

    2001-01-01

    We have established an empirical relationship between the dynamic and the static mechanical properties of North Sea and deep sea chalk for a large porosity interval with respect to porosity, effective stress history and textural composition. The chalk investigated is from the Tor and Hod Formatio...

  2. Dual hydraulic behaviour of the Chalk in the Netherlands North Sea

    NARCIS (Netherlands)

    Verweij, H.

    2006-01-01

    Information on the sedimentary development, seismic stratigraphy and burial compaction of the Chalk Group in the Netherlands North Sea was combined with pressure data and basin modelling to investigate the hydraulic behaviour of the Chalk Group in the Central Graben and Schill Grund High. The

  3. Change of Static and Dynamic Elastic Properties due to CO² Injection in North Sea Chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, M.L.; Christensen, H.F.

    2012-01-01

    important in enhanced oil recovery by CO2 injection (CO2-EOR) in chalk as, chalk reservoirs are vulnerable to compaction under changed stress and pore fluid. From South Arne field, North Sea, we used Ekofisk Formation chalk having approximately 20% non-carbonate and Tor Formation chalk having less than 5...

  4. Stylolites, porosity, depositional texture, and silicates in chalk facies sediments:Ontong Java Plateau - Gorm and Tyra fields, North Sea

    OpenAIRE

    Fabricius, Ida Lykke; Borre, Mai K.

    2007-01-01

    Comparison of chalk on the Ontong Java Plateau and chalk in the Central North Sea indicates that, whereas pressure dissolution is controlled by effective burial stress, pore-filling cementation is controlled by temperature. Effective burial stress is caused by the weight of all overlying water and sediments as counteracted by the pressure in the pore fluid, so the regional overpressure in the Central North Sea is one reason why the two localities have different relationships between temperatu...

  5. Fluid substitution studies for North Sea chalk logging data

    DEFF Research Database (Denmark)

    Gommesen, Lars; Mavko, G.; Mukerji, T.

    2002-01-01

    We have tested the application of respectively the Kuster-Toksöz and the Gassmann theory as a tool for predicting pore fluid from the elastic properties of brine-saturated North Sea reservoir chalk. We confirm that the Kuster-Toksöz model predicts a larger fluid effect thant the Gassmann model......, and show that the Kuster-Toksöz model fails to predict the presence of hydrocarbons. The Gassmann prediction for the near and potentially invaded zone corresponds more closely to logging data, than the Gassmann prediction for the far, virgin zone. We hereby conclude that the Gassmann theory predicts...

  6. Geochemical criteria for reservoir quality variations in chalk from the North Sea

    International Nuclear Information System (INIS)

    Kunzendorf, H.; Soerensen, P.

    1989-12-01

    The influence of chalk geochemistry on petrophysical parameters determining porosity and permeability is investigated. The central well TWB-8 and eastern marginal well E-lx of the North Sea Tyra gas field were chosen. Drill core sections of Upper Maastrichtian and Danian chalk were selected. Chemical data on chalk samples were gathered by using X-ray fluorescence and instrumental neutron activation. Geochemical data are compared with the well-logging results. Geophysical logging suggests that there is reduced porosity in the Danian reservoir units LDP and UDT in both wells. The chalk drill core samples from the section with reduced porosity also show a lower Ca content. A high Si content is observed in these samples and a number of trace elements in chalk show a similar distribution with depth. Reservoir porosity may be estimated from the Si content of chalk. Chalk permeability may also be elements Al, Fe and Sc show the same trends as that for Si. Diagenetic changes in chalk also include clay minerals. The gas zone in TWB-8 is characterized by low contents of Na and Cl, i.e. lower water saturation is indicated. Low concentrations of rare earths in all chalk samples show a shale-normalized pattern that is characteristic of marine sediments laid down under oxic conditions. Some changes that occur with depth in the Ce anomaly may indicate a slight change in the depositional environment. The content of manganese continuously decreases with depth, from Danian (about 2000 ppm) to Maastrichtian strata (less than 200 ppm). In this respect, no other chemical element in chalk correlates with Mn. There is no indication as to which mineral or mineral phase one is likely to find in the element. (AB) 14 tabs., 49 ills., 147 refs

  7. Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea

    DEFF Research Database (Denmark)

    Røgen, Birte; Fabricius, Ida Lykke

    2002-01-01

    specific surface area. Fifty-nine Tor and Ekofisk Formation chalk samples from five North Sea chalk reservoirs were investigated. All contain quartz and clay minerals, most commonly kaolinite and smectite, with trace amounts of illite. The contents of calcite and quartz are inversely correlated and both......)): calcite between 0.5 and 3.5, quartz about 5, kaolinite about 15, and smectite about 60....

  8. Current oil and gas production from North American Upper Cretaceous chalks

    Science.gov (United States)

    Scholle, Peter A.

    1977-01-01

    Production of oil and natural gas from North American chalks has increased significantly during the past five years, spurred by the prolific production from North Sea chalks, as well as by higher prices and improved production technology. Chalk reservoirs have been discovered in the Gulf Coast in the Austin Group, Saratoga and Annona Chalks, Ozan Formation, Selma Group, Monroe gas rock (an informal unit of Navarro age), and other Upper Cretaceous units. In the Western Interior, production has been obtained from the Cretaceous Niobrara and Greenhorn Formations. Significant, though subcommercial, discoveries of natural gas and gas condensate also have been made in the Upper Cretaceous Wyandot Formation on the Scotian Shelf of eastern Canada. All North American chalk units share a similar depositional and diagenetic history. The chalks consist primarily of whole and fragmented coccoliths with subordinate planktonic and benthonic Foraminifera, inoceramid prisms, oysters, and other skeletal grains. Most have between 10 and 35 percent HCl-insoluble residue, predominantly clay. Deposition was principally below wave base in tens to hundreds of meters of water. The diagenetic history of a chalk is critical in determining its reservoir potential. All chalk has a stable composition (low-Mg calcite) and very high primary porosity. With subsequent burial, mechanical and chemical (solution-transfer) compaction can reduce or completely eliminate pore space. The degree of loss of primary porosity in chalk sections is normally a direct function of the maximum depth to which it has been buried. Pore-water chemistry, pore-fluid pressures, and tectonic stresses also influence rates of cementation. Oil or gas reservoirs of North American chalk fall into three main groups: 1. Areas with thin overburden and significant primary porosity retention (for example, Niobrara Formation of Kansas and eastern Colorado). 2. Areas with thicker overburden but considerable fracturing. Here primary

  9. Towards an improved lithostratigraphic subdivision of the chalk group in the Netherlands North Sea area - A seismic stratigraphic approach

    NARCIS (Netherlands)

    Molen, A.S. van der; Wong, Th.E.

    2007-01-01

    In the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to Maastrichtian Ommelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphic subdivision for

  10. Towards an improved lithostratigraphic subdivision of the Chalk Group in the Netherlands North Sea area – A seismic stratigraphic approach

    NARCIS (Netherlands)

    Molen, A.S. van der; Wong, Th.E.

    In the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to MaastrichtianOmmelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphicsubdivision for

  11. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea

    Directory of Open Access Journals (Sweden)

    Finn Surlyk

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  12. Burial diagenesis of deep sea chalk as reflected in Biot's coefficient

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Alam, Mohammad Monzurul

    2013-01-01

    to limestone as burial increases and porosity decreases. The porosity decrease is accompanied by an increasing velocity to elastic waves, and consequently a decreasing Biot's coefficient, as estimated from velocity and density of core samples. When the effective burial stress is normalized to total horizontal....... In the ooze, we find that the natural compaction causes an increasing stress on grain contact area, indicating that the ooze particles become strongly strained. In the chalk section, contact cement is probably the reason why particles become less strained as porosity declines. In the limestone, stress...... on particles apparently is low and not correlated with porosity, probably because the pore-filling cementation in this interval causes Biot's coefficient to decline as burial increases. Limestone from the water zone of the North sea Chalk Group follows the same stress trend as deep sea limestone. These results...

  13. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea: Plate 1

    Directory of Open Access Journals (Sweden)

    Surlyk, Finn

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  14. Elastic behaviour of North Sea chalk

    DEFF Research Database (Denmark)

    Gommesen, Lars; Fabricius, Ida Lykke; Mukerji, T.

    2007-01-01

    -consistent approximation, which here represents the unrelaxed scenario where the pore spaces of the rock are assumed to be isolated, and the Gassmann theory, which assumes that pore spaces are connected, as tools for predicting the effect of hydrocarbons from the elastic properties of brine-saturated North Sea reservoir...

  15. Delineating chalk sand distribution of Ekofisk formation using probabilistic neural network (PNN) and stepwise regression (SWR): Case study Danish North Sea field

    Science.gov (United States)

    Haris, A.; Nafian, M.; Riyanto, A.

    2017-07-01

    Danish North Sea Fields consist of several formations (Ekofisk, Tor, and Cromer Knoll) that was started from the age of Paleocene to Miocene. In this study, the integration of seismic and well log data set is carried out to determine the chalk sand distribution in the Danish North Sea field. The integration of seismic and well log data set is performed by using the seismic inversion analysis and seismic multi-attribute. The seismic inversion algorithm, which is used to derive acoustic impedance (AI), is model-based technique. The derived AI is then used as external attributes for the input of multi-attribute analysis. Moreover, the multi-attribute analysis is used to generate the linear and non-linear transformation of among well log properties. In the case of the linear model, selected transformation is conducted by weighting step-wise linear regression (SWR), while for the non-linear model is performed by using probabilistic neural networks (PNN). The estimated porosity, which is resulted by PNN shows better suited to the well log data compared with the results of SWR. This result can be understood since PNN perform non-linear regression so that the relationship between the attribute data and predicted log data can be optimized. The distribution of chalk sand has been successfully identified and characterized by porosity value ranging from 23% up to 30%.

  16. Productivity, facies and stable-isotope records of OAE2 (Cenomanian - Turonian) in the NW European epicontinental sea: from the English Chalk to North Sea black shales

    Science.gov (United States)

    Jarvis, Ian; Olde, Kate; Trabucho-Alexandre, João; Gröcke, Darren

    2013-04-01

    The Late Cretaceous (100.5 - 66.0 Ma) provides perhaps the best example of how the Earth System may function under long-term extreme greenhouse conditions. Rapidly rising global temperatures indicate that we are heading 'back to the Cretaceous' within a few hundred years, so a better understanding of this time interval is essential. The beginning of the Late Cretaceous was characterized by a period of rapidly rising eustatic sea level, the Cenomanian transgression, which flooded continental margins and established large areas of new epicontinental sea that accumulated thick sequences of pelagic and hemipelagic carbonate (chalk). Highest global temperatures were reached during the early part of the Turonian Stage (93.9 - 89.8 Ma). This period of dramatic palaeoenvironmental change was accompanied by one the largest perturbations of the global carbon cycle in the Mesozoic: Oceanic Anoxic Event 2 (OAE2), which was characterized by a 500 kyr episode of oceanic anoxia, widespread black shale deposition, biotic turnover, and a large global positive carbon stable-isotope excursion (2 - 6 ‰ ∂13C) recorded in marine carbonates and both marine and terrestrial organic matter. The Cenomanian-Turonian boundary interval exposed at Eastbourne, southern England, has become established as a European reference section for OAE2. Here, and elsewhere in Europe, the base of the ∂13C excursion is coincident with a marked facies change from rhythmically bedded grey chalks and marls, to a >8 m thick package of dark greenish-grey marl - the Plenus Marl. The termination of OAE2 occurs 6 m above, in a package of pale-yellow-weathering nodular chalks with prominent marl seams. Sediments are organic lean (10 wt%. The onshore equivalent in eastern England (the Black Band) is similarly organic-rich, as are comparable sections in northern Germany (e.g. Wunstorf), indicating likely fully anoxic episodes within some NW European basins. The exact stratigraphic equivalence between the onshore

  17. The sedimentology of redeposited chalk

    DEFF Research Database (Denmark)

    Anderskouv, Kresten; Surlyk, Finn; Gale, Andy

    Redeposited facies in the Upper Cretaceous Chalk Group constitute major hydrocarbon reservoirs in the North Sea Central Graben. Existing facies models are largely based on publications from the early 1980's dealing with core material from the Norwegian sector. However, the recognition, interpreta...

  18. Pitfalls in velocity analysis for strongly contrasting, layered media - Example from the Chalk Group, North Sea

    Science.gov (United States)

    Montazeri, Mahboubeh; Uldall, Anette; Moreau, Julien; Nielsen, Lars

    2018-02-01

    Knowledge about the velocity structure of the subsurface is critical in key seismic processing sequences, for instance, migration, depth conversion, and construction of initial P- and S-wave velocity models for full-waveform inversion. Therefore, the quality of subsurface imaging is highly dependent upon the quality of the seismic velocity analysis. Based on a case study from the Danish part of the North Sea, we show how interference caused by multiples, converted waves, and thin-layer effects may lead to incorrect velocity estimation, if such effects are not accounted for. Seismic wave propagation inside finely layered reservoir rocks dominated by chalk is described by two-dimensional finite-difference wave field simulation. The rock physical properties used for the modeling are based on an exploration well from the Halfdan field in the Danish sector of the North Sea. The modeling results are compared to seismic data from the study area. The modeling shows that interference of primaries with multiples, converted waves and thin-bed effects can give rise to strong anomalies in standard velocity analysis plots. Consequently, root-mean-square (RMS) velocity profiles may be erroneously picked. In our study area, such mis-picking can introduce errors in, for example, the thickness estimation of the layers near the base of the studied sedimentary strata by 11% to 26%. Tests show that front muting and bandpass filtering cannot significantly improve the quality of velocity analysis in our study. However, we notice that spiking deconvolution applied before velocity analysis may to some extent reduce the impact of interference and, therefore, reduce the risk of erroneous picking of the velocity function.

  19. Use of X-ray computed tomography in core analysis of tight North Sea Chalk. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mogensen, K.; Stenby, E.H.

    1997-12-01

    This EFP-95 final report summarizes work performed at the Engineering Research Center (IVC-SEP) on the use of CT scanning in core analysis of tight core material from the North Sea. In this work, CT scanning has been applied to chalk material from Danish North Sea oil reservoirs. Results indicate that CT is fast and reliable for prediction of porosity. Typical errors lie within 2-3%. Calculation of fluid saturations requires considerable care from the experimentalists. Saturating a core ought to be performed by pulling vacuum to avoid trapped air bubbles. These bubbles may be produced after subsequent water and gas flooding, thereby ruining the mass balance calculations. Results performed at Stanford University show that if these simple precautions are taken, fluid saturations calculated from CT scanning are generally very accurate. Moreover, it appears that contrast agents need not be added to either phase. Regarding three-phase measurements the results are somewhat disappointing. Previous work using the dual-energy technique has indicated that the accuracy is less than satisfactory, due to an increased noise level at the low-energy setting. More work needs to be done in the future to develop the necessary expertise. The image analysis of the residual oil saturation after a gas flood can be simplified if water is assumed to be immobile during the injection. In that case, the resulting prediction of residual oil saturation is in excellent agreement with measured values. The general conclusion is that CT scanning holds a great potential as an assisting tool in modern core analysis, despite its limitations and the numerous implementation-related problems encountered during this work. (au) EFP-95. 57 refs.

  20. Trace elements in a North Sea drill core

    DEFF Research Database (Denmark)

    Kunzendorf, Helmar; Gwozdz, R.; Svendsen, N.

    1986-01-01

    , V, Sr, Dy, Mg, Ti, Ba and Eu. The major elements Ca and Al could be related to petrophysical parameters, particularly Al which shows a correlation with the silicification/argillaceous content. Na (and Cl) has a low content in the hydrocarbon-bearing section of the drill core suggesting that the pore......Chalk samples, systematically taken along a drill core from one of the hydrocarbon producing fields of the North Sea (Tyra field), were analysed by a neutron activation technique involving measurement of radioisotopes with relatively short half-lives. Elements determined include Na, Al, Cl, Ca, Mn...... space is filled mainly by hydrocarbons. A significant decrease of Mn with depth probably suggests diagenesis of chalk prior to, or with, hydrocarbon emplacement. Investigations of drilling fluids and cuttings reveal a strong contamination of the latter, mainly by Ba. Chalk data from comparable onshore...

  1. Chalk porosity and sonic velocity versus burial depth

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Gommesen, Lars; Krogsbøll, Anette Susanne

    2008-01-01

    Seventy chalk samples from four formations in the overpressured Danish central North Sea have been analyzed to investigate how correlations of porosity and sonic velocity with burial depth are affected by varying mineralogy, fluid pressure, and early introduction of petroleum. The results show th...... for fluid pressure because the cementing ions originate from stylolites, which are mechanically similar to fractures. We find that cementation occurs over a relatively short depth interval.......Seventy chalk samples from four formations in the overpressured Danish central North Sea have been analyzed to investigate how correlations of porosity and sonic velocity with burial depth are affected by varying mineralogy, fluid pressure, and early introduction of petroleum. The results show...... that porosity and sonic velocity follow the most consistent depth trends when fluid pressure and pore-volume compressibility are considered. Quartz content up to 10% has no marked effect, but more than 5% clay causes lower porosity and velocity. The mineralogical effect differs between P-wave and shear velocity...

  2. Lithostratigraphy of the Palaeogene - Lower Neogene succession of the Danish North Sea

    DEFF Research Database (Denmark)

    Schiøler, Poul-Henrik; Andsbjerg, Jan; Clausen, Ole Rønø

    2007-01-01

    sediments of the Danish sector of the North Sea is revised. The sediment package from the top of the Chalk Group to the base of the Nordland Group is subdivided into seven formations containing eleven new members. The existing Våle, Lista, Sele, Fur, Balder, Horda and Lark Formations of previously...

  3. Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution

    DEFF Research Database (Denmark)

    Hassenkam, Tue; Skovbjerg, Lone Lindbæk; Stipp, Susan Louise Svane

    2009-01-01

    been drilled in a water-bearing formation. At this site, the chalk has never seen oil, though at other locations, the same stratigraphic horizon with the same rock properties is known to be a productive oil reservoir. Thus the properties of the investigated particle surfaces are inherent to the chalk......Ultimate Oil recovery from chalk reservoirs is limited by many factors - including the grain size and the surface properties of the small mainly biogenic calcite particles that chalk is made off . Wettability, the tendency for water or oil to spread over a surface, of the particle surfaces is one...... of the controlling factors for the effectiveness of water flooding, one of the most common methods to improve oil recovery in Chalk reservoirs. Understanding surface wetting and its variability at scales smaller than the pore dimension will potentially provide clues for more effective oil production methods. We used...

  4. Waveform analysis of crosshole GPR data collected in heterogeneous chalk deposits

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Nielsen, Lars; Zibar, Majken Caroline Looms

    2014-01-01

    Chalks are important reservoirs for groundwater production onshore Denmark and for hydrocarbons in the North Sea Basin. Therefore this rock type is studied extensively with geological and geophysical methods. Ground-penetrating radar (GPR) tomography is used to characterize fine-scale reservoir...

  5. Full-waveform inversion of cross-hole GPR data collected in a strongly heterogeneous chalk reservoir analogue with sharp permittivity and conductivity contrasts

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Zibar, Majken Caroline Looms; Moreau, Julien

    2014-01-01

    Chalk sediments form an important reservoir for groundwater onshore and for hydrocarbons in the Danish sector of the North Sea. Cross-hole Ground-penetrating radar (GPR) tomography is an efficient method to investigate subtle porosity variations in the chalk. Traditional ray-based inversion...

  6. Diagenetic Variations between Upper Cretaceous Outcrop and Deeply Buried Reservoir Chalks of the North Sea Area

    DEFF Research Database (Denmark)

    Hjuler, Morten Leth; Fabricius, Ida Lykke

    2007-01-01

    -particle connections and less altered particle shapes. The non-carbonate mineralogy of outcrop chalks is dominated by quartz, occasionally opal-CT and clinoptilolite, and the clay mineral smectite. In offshore chalks quartz still dominates, opal-CT has recrystallized into submicron-size quartz crystals and smectite...

  7. Glaciotectonic deformations in the Jammerbugt and glaciodynamic development in the eastern North Sea

    DEFF Research Database (Denmark)

    Pedersen, Stig A. Schack; Boldreel, Lars Ole

    2017-01-01

    –Early Weichselian Skærumhede Group, indicating a Saalian age of the glaciotectonic deformation. The balancing of the thrust fault structures shows that the thrust sheets in the tailing end of the complex had their source in the Skagerrak sea. The hole caused by displacement contributed to formation of the Skagerrak......The Quaternary geology in the eastern part of the North Sea is characterized by large-scale glaciotectonic complexes. The northernmost complex is the Jammerbugt Glaciotectonic Complex here addressed, which occupies an area of more than 300km2. It was recently recognized during an investigation...... of conventional seismic profiles located about 10km offshore the west coast of northern Denmark. The deformed bedrock includes the main part of the Cretaceous Chalk Group in the North Sea. In the northern part of the complex the detachment surface is situated in Lower Cretaceous greensand about 400m below sea...

  8. Water in chalk reservoirs: 'friend or foe?'

    International Nuclear Information System (INIS)

    Hjuler, Morten Leth

    2004-01-01

    Most of the petroleum fields in the Norwegian sector of the North Sea are sandstone reservoirs; the oil and gas are trapped in different species of sandstone. But the Ekofisk Field is a chalk reservoir, which really challenges the operator companies. When oil is produced from chalk reservoirs, water usually gets in and the reservoir subsides. The subsidence may be expensive for the oil companies or be used to advantage by increasing the recovery rate. Since 60 per cent of the world's petroleum reserves are located in carbonate reservoirs, it is important to understand what happens as oil and gas are pumped out. Comprehensive studies at the Department of Petroleum Technology and Applied Geophysics at Stavanger University College in Norway show that the mechanical properties of chalk are considerably altered when the pores in the rock become saturated with oil/gas or water under different stress conditions. The processes are extremely complex. The article also maintains that the effects of injecting carbon dioxide from gas power plants into petroleum reservoirs should be carefully studied before this is done extensively

  9. Cenozoic structures and the tectonic evolution of the eastern North Sea

    DEFF Research Database (Denmark)

    Clausen, O.R.; Nielsen, S.B.; Egholm, D.L.

    2011-01-01

    Abundant seismic sections and well data from the Cenozoic succession in the eastern North Sea area generally reveal normal faulting, salt tectonics and localized tectonic inversion. However, inferences on the Cenozoic dynamic evolution of the region require thorough analysis of interactions between...... or cover tectonism took place. Our objectives are thus 1) to analyze the interaction between basement and cover structures, and if possible 2) to relate the structures to the regional tectonic evolution. The Zechstein evaporites pinch out onto the Ringkøbing-Fyn High, which in the eastern North Sea...... influencede.g. Miocene deposition and controlled the generation of second order faults. The latter detached along the top Chalk Group due to the topography generated during faulting, i.e. they are second order detachment surfaces. We conclude that the regional tectonic significance of the Cenozoic structures...

  10. Impact of supercritical CO2 injection on petrophysical and rock mechanics properties of chalk: an experimental study on chalk from South Arne field, North Sea

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, Morten Leth; Christensen, Helle Foged

    2011-01-01

    Changes in chalk due to EOR by injecting supercritical CO2 (CO2-EOR) can ideally be predicted by applying geophysical methods designed from laboratory-determined petrophysical and rock mechanics properties. A series of petrophysical and rock mechanics tests were performed on Ekofisk Formation...... and Tor Formation chalk of the South Arne field to reveal the changes in petrophysical and rock mechanics properties of chalk due to the injection of CO2 at supercritical state. An increase in porosity and decrease in specific surface was observed due to injection of supercritical CO2. This indicates...... as indicated by NMR T2 relaxation time was observed. Rock mechanics testing indicates that in 30% porosity chalk from the South Arne field, injection of supercritical CO2 has no significant effect on shear strength and compaction properties, while there is probably a slight decrease in stiffness properties...

  11. Managing Injected Water Composition To Improve Oil Recovery: A Case Study of North Sea Chalk Reservoirs

    DEFF Research Database (Denmark)

    Zahid, Adeel; Shapiro, Alexander; Stenby, Erling Halfdan

    2012-01-01

    of the temperature dependence of the oil recovery indicated that the interaction of the ions contained in brine with the rock cannot be the only determining mechanism of enhanced recovery. We observed no substitution of Ca2+ ions with Mg2+ ions at high temperatures for both rocks. Not only the injection brine......In recent years, many core displacement experiments of oil by seawater performed on chalk rock samples have reported SO42–, Ca2+, and Mg2+ as potential determining ions for improving oil recovery. Most of these studies were carried out with outcrop chalk core plugs. The objective of this study...... is to investigate the potential of the advanced waterflooding process by carrying out experiments with reservoir chalk samples. The study results in a better understanding of the mechanisms involved in increasing the oil recovery with potential determining ions. We carried out waterflooding instead of spontaneous...

  12. Seismic geomorphology and origin of diagenetic geobodies in the Upper Cretaceous Chalk of the North Sea Basin (Danish Central Graben)

    DEFF Research Database (Denmark)

    Smit, F. W. H.; van Buchem, F.S.P.; Holst, J.H.

    2018-01-01

    that the geobodies are of an open-system diagenetic origin caused by ascending basin fluids guided by faults and stratigraphic heterogeneities. Increased amounts of porosity-occluding cementation, contact cement and/or high-density/-velocity minerals caused an impedance contrast that can be mapped in seismic data...... failure, followed by local mechanical compaction of high-porous chalks, paired with 2) ascension of basinal diagenetic fluids along fault systems that locally triggered cementation of calcite and dolomite within the chalk, causing increased contact cements and/or reducing porosity. The migration pathway...... of the fluids is marked by the SCRs, which are the outlines of high-density bodies of chalk nested in highly porous chalks. This study thus provides new insights into the 3D relationship between fault systems, fluid migration and diagenesis in chalks, and has important applications for basin modeling...

  13. Tilting oil-water contact in the chalk of Tyra Field as interpreted from capillary pressure data

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Rana, M.A.

    2010-01-01

    The Tyra Field in the central North Sea is located in Palaeogene and Upper Cretaceous chalk. It contains a natural gas zone underlain by an oil leg. Based on analysis of logs and core data from ten wells drilled prior to the field being put into production, normalized water saturation depth-trend...... inequilibriumin the aquifer following tectonic tilting....

  14. Deep saltwater in Chalk of North-West Europe: origin, interface characteristics and development over geological time

    DEFF Research Database (Denmark)

    Bonnesen, Ellen Prip; Larsen, F.; Sonnenborg, T.O.

    2009-01-01

    High-concentration saltwaters occur in many places in the regional Chalk aquifers of North-West Europe; to investigate deep occurrences, profiles of interstitial porewater chemistry have been studied from three 250-450m deep cores drilled in the eastern parts of Zealand, Denmark. At the studied...

  15. Elements of seismic imaging and velocity analysis – Forward modeling and diffraction analysis of conventional seismic data from the North Sea

    DEFF Research Database (Denmark)

    Montazeri, Mahboubeh

    2018-01-01

    comprises important oil and gas reservoirs. By application of well-established conventional velocity analysis methods and high-quality diffraction imaging techniques, this study aims to increase the resolution and the image quality of the seismic data. In order to analyze seismic wave propagation......-outs and salt delineations, which can be extracted from the diffractions. The potential of diffraction imaging techniques was studied for 2D seismic stacked data from the North Sea. In this approach, the applied plane-wave destruction method was successful in order to suppress the reflections from the stacked....... This improved seismic imaging is demonstrated for a salt structure as well as for Overpressured Shale structures and the Top Chalk of the North Sea....

  16. Regional hardening of Upper Cretaceous Chalk in eastern England, UK: trace element and stable isotope patterns in the Upper Cenomanian and Turonian Chalk and their significance

    Science.gov (United States)

    Jeans, Christopher V.; Long, Dee; Hu, Xiu-Fang; Mortimore, Rory N.

    2014-12-01

    fluids, rich in sulphate and hydrocarbons, derived probably from the North Sea Basin. Microbial sulphate-reduction under anoxic conditions within these allochthonous fluids has been responsible for dissolving the fine-grained iron and manganese oxides within the chalk, locally enriching the Fe and Mn content of the calcite cement. The possibility is discussed that the pattern of cementation preserved in these regionally hard chalks of Late Cenomanian and Early Turonian age may be different from that preserved in the younger (late Turonian to Campanian) more basinal chalks of eastern England.

  17. Microbial Fluid-Rock Interactions in Chalk Samples and Salinity Factor in Divalent Ca2+ ions Release for Microbial Enhanced Oil Recovery Purposes

    DEFF Research Database (Denmark)

    Jimoh, Ismaila Adetunji; Rudyk, Svetlana Nikolayevna; Søgaard, Erik Gydesen

    2011-01-01

    In this study, laboratory experiments were performed on chalk samples from Danish sector of the North Sea to study microbial fluid-rock interactions with carbonate rock and to evaluate the dissolution of rock matrix (CaCO3). Result showed that the average concentration of Ca2+ ions after microbia...

  18. Investigation of spore forming bacterial flooding for enhanced oil recovery in a North Sea chalk Reservoir

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Nielsen, Sidsel Marie; Eliasson Lantz, Anna

    2015-01-01

    Little has been done to study microbial enhanced oil recovery (MEOR) in chalk reservoirs. The present study focuses on core flooding experiments designed to see microbial plugging and its effect on oil recovery. A pressure tapped core holder was used for this purpose. A spore forming bacteria...... Bacillus licheniformis 421 was used as it was shown to be a good candidate in a previous study. Bacterial spore can penetrate deeper into the chalk rock, squeezing through the pore throats. Our results showed that injection of B. licheniformis 421 as a tertiary oil recovery method, in the residual oil...... saturation state, was able to produce additionally 1.0-2.3% original oil in place (OOIP) in homogeneous cores and 6.9-8.8% OOIP in heterogeneous cores. In addition, the pressure gradient was much higher in the heterogeneous cores, which confirms that bacterial selective plugging plays an important role...

  19. Effective stresses and shear failure pressure from in situ Biot's coefficient, Hejre Field, North Sea

    DEFF Research Database (Denmark)

    Regel, Jeppe Bendix; Orozova-Bekkevold, Ivanka; Andreassen, Katrine Alling

    2017-01-01

    , is significantly different from 1. The log-derived Biot's coefficient is above 0.8 in the Shetland Chalk Group and in the Tyne Group, and 0.6-0.8 in the Heno Sandstone Formation. We show that the effective vertical and horizontal stresses obtained using the log-derived Biot's coefficient result in a drilling......We propose a combination of Biot's equations for effective stress and the expression for shear failure in a rock to obtain an expression for minimum pore pressure in a stable vertical well bore. We show that a Biot's coefficient calculated from logging data in the Hejre Field, North Sea...

  20. Rock physical aspects of CO{sub 2} injection in chalk

    Energy Technology Data Exchange (ETDEWEB)

    Alam, M.M.

    2011-04-15

    Impact of supercritical CO{sub 2} on the petrophysical and rock-mechanics properties of Ekofisk Formation and Tor Formation chalk from South Arne field, Danish North Sea, chalk was investigated. A series of laboratory experiments was performed on core material collected from the reservoir zone of the South Arne field in order to reveal the changes with respect to porosity, specific surface, pore stiffness, wettability, mineralogy and mechanical failure. In addition, a theoretical rock physical background was also established in order to be able to make sensible interpretation of laboratory data. Sound wave velocity was used as the central tool to study any change in petrophysical and rock mechanical properties. The main focus was to achieve a better understanding of effective stress coefficient (also known as Biot's coefficient); by means of which effective stress can be predicted more accurately. Independent theoretical studies were made on diagenesis, surface properties and stiffness of chalk and their relation with sonic velocity (or Biot's coefficient calculated from sonic velocity). The knowledge and experience from these studies was combined to achieve the main research objective of monitoring changes in hydrocarbon reservoirs in chalk due to CO{sub 2} injection. In order to understand the development of chalk from calcareous ooze and achieving pore stiffness, the diagenesis process of a sedimentary sequence from Kerguelen Plateau in the Indian Ocean was studied. The principal objective of the study was to explore how different porosity reduction mechanisms change the strength of these deep sea carbonate-rich sediments and how these mechanisms can be traced from the change in Biot's coefficient, alpha. In calcareous ooze, alpha was found close to one. Mechanical compaction reduces porosity, but only leads to a minor decrease in alpha. Recrystallization process renders particles smoother, but do not lead to reduction in alpha unless it gives

  1. Air-sea exchange studies at the North Sea

    NARCIS (Netherlands)

    Leeuw, G. de; Eijk, A.M.J. van; Kunz, G.J.; Veefkind, P.J.

    1996-01-01

    The North Sea can be considered as a local 'inner' sea in which many processes are quite different from these over the open ocean. The surrounding land has a major influence, being the source for man-made aerosols and gases, whereas the North Sea acts as a sink for these. At the same time the North

  2. Optimization of Spore Forming Bacteria Flooding for Enhanced Oil Recovery in North Sea Chalk Reservoir

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Nielsen, Sidsel Marie; Eliasson Lantz, Anna

    2015-01-01

    .2-3.8 cm) during bacteria injection. Further seawater flooding after three days shut in period showed that permeability gradually increased in the first two sections of the core and started to decrease in the third section of the core (3.8-6.3 cm). Complete plugging was never observed in our experiments.......Little has been done to study microbial enhanced oil recovery (MEOR) in chalk reservoirs. The present study focused on core flooding experiments to see microbial plugging and its effect on oil recovery. A pressure tapped core holder with pressure ports at 1.2 cm, 3.8 cm, and 6.3 cm from the inlet...

  3. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    Science.gov (United States)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    chalk surfaces and partly by adsorbed organic material. GS < GS after extraction < WS < WS after extraction < Ålborg after extraction ⩽ Ålborg. The increase of spreading work for WS chalk for ethanol is 21 mN/m and for water is 26 mN/m, a ratio of 21/26 = 0.81. The increase of spreading work for GS chalk for ethanol and water are 36 and 42 mN/m, a ratio of 36/42 = 0.86. The similarity between these ratios leads us to conclude, that the surface that was produced by extraction of the organic material is quite similar for these two samples.The total surface energy increase, after the extraction of organics, for GS and WS was 67 and 49 mJ/m2. Further separation of surface energy into polar and dispersive parts showed that, for both samples, removing organic matter by extraction preferably increases the dispersive component of the surface energy. The contribution from dispersive surface energy to the increase in total surface energy was 87% for GS and 73% for WS chalk. A high relative proportion of dispersive component in the total surface energy is also typical for clay minerals (Chassin et al., 1986; Jouany and Chassin, 1987; Kádár et al., 2006).This demonstrates that the additional adsorption sites that are exposed by the extraction procedure are less polar than the sites originally exposed. Based on these results, we can conclude that chalk particles have surface sites of different polarity and that organic compounds preferentially adsorb at the less polar sites. These additional sites have quite similar surface properties for both North Sea chalk samples with an energy distribution that is similar to clays, that are described in the literature (Chassin et al., 1986; Jouany and Chassin, 1987; Kádár et al., 2006).The Ålborg chalk initially has minimal adsorbed organic material and the work of wetting changes very little after the treatment for extracting organic material. Considering the lower reproducibility of the results on Ålborg chalk, the differences in

  4. The North Sea field development guide. V.1: Northern North Sea. V.2: Southern North Sea. 6. ed.

    International Nuclear Information System (INIS)

    Anon.

    1996-08-01

    The 1997/8, sixth edition is the first to be divided into two volumes. Volume 1 covers the central and northern North Sea areas; volume 2 contains the southern North Sea as well as the Irish and German sectors. The pages are numbered consecutively over the two volumes, with page numbers greater than 702 contained in the second volume. There are three index sections. Main index. Arranged by national sector (UK, Norway etc.) Within each sector the entries are alphabetical by operator name. This index contains page numbers for the book entries: the other two index sections should be used with the main index to find the exact location of an entry; Index by field. If the reader knows a field name (e.g. Kittiwake) but not the operator or the national sector, this index will reference them; Index by installation. Each installation (''Fulmar SALM'', ''Togi'') is named, giving the operator, field and national sector where it is located. This index is also useful for locating particular kinds of installations, such as subsea completions; The book is intended to provide a factual overview of field development activity in the North Sea (a term loosely used to include the Irish Sea and the Baltic Sea). The aim is therefore to provide some background, specifications and history on every offshore installation in that area. Speculative or evaluative commentary is avoided where possible. No attempt has been made to forecast the form or probability of future developments, except in those few instances where announcements have been made by the oil company itself, and these are, clearly indicated. (UK)

  5. The pollution of the North Sea

    International Nuclear Information System (INIS)

    1981-01-01

    The subject is covered in chapters entitled: the North Sea and its rivers; the uses of the North Sea (shipping; exploitation of oil and gas; fishing; recreation; land reclamation; industrial islands; waste dumping); the nature of the dumping problem (nuclear waste; organic chemicals; inorganic chemicals; oil; sewage; rubble and dredged spoils; ash); pollution legislation; Greenpeace activities in the North Sea (the nuclear campaigns (Windscale; Cap de la Hague; Atlantic waste dumping); the chemical campaigns); what is needed in the future; references; the Oslo Convention. (U.K.)

  6. Stability analysis of chalk sea cliffs using UAV photogrammetry

    Science.gov (United States)

    Barlow, John; Gilham, Jamie

    2017-04-01

    Cliff erosion and instability poses a significant hazard to communities and infrastructure located is coastal areas. We use point cloud and spectral data derived from close range digital photogrammetry to assess the stability of chalk sea cliffs located at Telscombe, UK. Data captured from an unmanned aerial vehicle (UAV) were used to generate dense point clouds for a 712 m section of cliff face which ranges from 20 to 49 m in height. Generated models fitted our ground control network within a standard error of 0.03 m. Structural features such as joints, bedding planes, and faults were manually mapped and are consistent with results from other studies that have been conducted using direct measurement in the field. Kinematic analysis of these data was used to identify the primary modes of failure at the site. Our results indicate that wedge failure is by far the most likely mode of slope instability. An analysis of sequential surveys taken from the summer of 2016 to the winter of 2017 indicate several large failures have occurred at the site. We establish the volume of failure through change detection between sequential data sets and use back analysis to determine the strength of shear surfaces for each failure. Our results show that data capture through UAV photogrammetry can provide useful information for slope stability analysis over long sections of cliff. The use of this technology offers significant benefits in equipment costs and field time over existing methods.

  7. Benthic community structures in the North Sea

    Science.gov (United States)

    Heip, C.; Craeymeersch, J. A.

    1995-03-01

    Coherent assemblages of marine benthic species have been recognized from the early twentieth century, and the classical papers of Petersen (1914, 1918) were based on studies of limited areas in the North Sea. In 1986, a synoptic survey of the North Sea north to 57°N was undertaken by a group of ten laboratories from seven North Sea countries. The results of this survey have recently been published (Heip et al., 1992a, b; Künitzer et al., 1992; Huys et al., 1992), and some of the results are summarized in this paper. The analysis of the macrofauna is based on slightly more than 700 taxa. In general, the North Sea macrofauna consists of northern species extending south to the northern margins of the Dogger Bank, and southern species extending north to the 100 m depth line. The central North Sea is an area of overlap of southern and northern species, especially around the 70 m depth contour. Consistent groupings of species are recognized that were summarized in seven faunal groupings. Macrofaunal body weight, density and diversity increase linearly towards the north. Macrofaunal biomass for the whole area averages 7 g adwt. m-2 and decreases from south to north. Distribution patterns and trends within the meiofauna were very different. Nematodes, which are the dominant taxon overall, are least abundant in the sandy sediments of the Southern Bight, then increase to a maximum around 53° 30' N and slowly decrease again towards the north. Copepod density and diversity are highest in the Southern Bight, due to the presence of many interstitial species. A large number of species new to science were recorded by the North Sea Benthos Survey and about 1500 species are expected to occur. Copepods show very distinct assemblages according to water depth and sediment type. The contrasting patterns in latitudinal gradients of body weight and number of species of macro- and meiofauna can be only partially explained. Latitude and sediment characteristics, such as grain size and

  8. Scientific symposium on the North Sea quality status report 1993

    International Nuclear Information System (INIS)

    Andersen, J.; Karup, H.; Nielsen, U.B.

    1996-01-01

    The Scientific Symposium on the 1993 North Sea quality Status Report took place in Ebeltoft, Denmark from 18 to 21 April 1994. The aim was to bring together scientists, researchers and administrators from governments, industries and environmental organizations from the countries around the North Sea in order to review new information which may supplements the 1993 North Sea Quality Status Report and to discuss the Quality Status Report and its possible implications. The 1993 North Sea Quality Status Report has been prepared by the North Sea Task force as a comprehensive statement of circulation patterns, inputs and dispersion of contaminants, ecological conditions and effects of human activities in the North Sea including the Skagerrak and the Kattegat. The programme of the Scientific Symposium on the 1993 North Sea Quality Status Report included 8 sessions for oral presentations, a poster session presenting the North Sea Task Force subregional reports and a poster session presenting individual posters. The headings of the sessions were as follows: Oceanography, Models and Remote Sensing; Ecosystem Structure; Contaminants -Distribution and Effects; Nutrients and Eutrophication Problems; Effects of Fishery; Habitats and Species; Management Implications; Conclusions and Recommendations. The proceedings includes a total of 45 contributed papers. (EG)

  9. Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian Sea and White Sea from R/Vs Artemovsk, Atlantida, Okeanograf, Professor Rudovits, and ice observations, 1957 - 1995 (NODC Accession 0073674)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian...

  10. North Sea oil directory 1976

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-01

    This edition of the North Sea Oil Directory has been revised to keep pace with the ever-changing North Sea industry. The information is grouped under the following topics: exploration and production; group licensees; Dutch and Norwegian licensees; UK Offshore Operators Association Committees; drilling contractors; offshore exploration and surveys; cement, drilling fluids, and related equipment; drilling equipment; prime mover, transmission equipment; production and process equipment; rig and platform equipment suppliers; rig builders, ship builders; rig and platform logistics; ports, supply bases; marine civil engineering; specialized equipment and services; classified index; and an alphabetical index. (MCW)

  11. How attractive is the North Sea to the financial community?

    International Nuclear Information System (INIS)

    Arnott, R.

    1992-01-01

    How attractive is the North Sea to the financial community? This question is answered by discussing the type of investment opportunity that the North Sea offers the investor. It is shown how North Sea investments have performed and some of the methods used to measure that performance are discussed. Finally, some thoughts on the future importance of the North Sea to the financial community reach the conclusion that it will remain important for some years to come. (author)

  12. The carbon budget of the North Sea

    NARCIS (Netherlands)

    Thomas, H.; Bozec, Y.; Baar, H.J.W. de; Elkalay, K.; Frankignoulle, M.; Schiettecatte, L.-S.; Kattner, G.; Borges, A.V.; Gattuso, J.-P.

    2005-01-01

    A carbon budget has been established for the North Sea, a shelf sea on the NW European continental shelf. The carbon exchange fluxes with the North Atlantic Ocean dominate the gross carbon budget. The net carbon budget – more relevant to the issue of the contribution of the coastal ocean to the

  13. ChalkBoard: Mapping Functions to Polygons

    Science.gov (United States)

    Matlage, Kevin; Gill, Andy

    ChalkBoard is a domain specific language for describing images. The ChalkBoard language is uncompromisingly functional and encourages the use of modern functional idioms. ChalkBoard uses off-the-shelf graphics cards to speed up rendering of functional descriptions. In this paper, we describe the design of the core ChalkBoard language, and the architecture of our static image generation accelerator.

  14. Sea level anomaly in the North Atlantic and seas around Europe: Long-term variability and response to North Atlantic teleconnection patterns.

    Science.gov (United States)

    Iglesias, Isabel; Lorenzo, M Nieves; Lázaro, Clara; Fernandes, M Joana; Bastos, Luísa

    2017-12-31

    Sea level anomaly (SLA), provided globally by satellite altimetry, is considered a valuable proxy for detecting long-term changes of the global ocean, as well as short-term and annual variations. In this manuscript, monthly sea level anomaly grids for the period 1993-2013 are used to characterise the North Atlantic Ocean variability at inter-annual timescales and its response to the North Atlantic main patterns of atmospheric circulation variability (North Atlantic Oscillation, Eastern Atlantic, Eastern Atlantic/Western Russia, Scandinavian and Polar/Eurasia) and main driven factors as sea level pressure, sea surface temperature and wind fields. SLA variability and long-term trends are analysed for the North Atlantic Ocean and several sub-regions (North, Baltic and Mediterranean and Black seas, Bay of Biscay extended to the west coast of the Iberian Peninsula, and the northern North Atlantic Ocean), depicting the SLA fluctuations at basin and sub-basin scales, aiming at representing the regions of maximum sea level variability. A significant correlation between SLA and the different phases of the teleconnection patterns due to the generated winds, sea level pressure and sea surface temperature anomalies, with a strong variability on temporal and spatial scales, has been identified. Long-term analysis reveals the existence of non-stationary inter-annual SLA fluctuations in terms of the temporal scale. Spectral density analysis has shown the existence of long-period signals in the SLA inter-annual component, with periods of ~10, 5, 4 and 2years, depending on the analysed sub-region. Also, a non-uniform increase in sea level since 1993 is identified for all sub-regions, with trend values between 2.05mm/year, for the Bay of Biscay region, and 3.98mm/year for the Baltic Sea (no GIA correction considered). The obtained results demonstrated a strong link between the atmospheric patterns and SLA, as well as strong long-period fluctuations of this variable in spatial and

  15. North Sea oil and gas: a geographical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, K

    1976-01-01

    Only ten years after the first rig moved into position, British oil has been piped ashore from the North Sea and, by 1980, will be making a substantial contribution to UK energy supplies. The discovery of natural gas in 1967--for initially gas was the primary objective--has transformed the gas supply so that 90% of the UK's needs already come from the North Sea. The speed and concentration of exploration pinpoints the vital importance of this new energy source. Until now the major oil 'pipeline' in the world has been led between the Middle East and Western Europe, so this new energy source has far reaching implications, both political and economic. Keith Chapman examines these implications starting from events in the North Sea itself; the geological background, agreement on the division of the North Sea, relations between oil companies, and government embodied in offshore mining legislation. The latter part of the book concentrates on the onshore repercussions of offshore activities; how North Sea oil fits into the international oil system, the various options open for its utilisation, the attitude of the EEC towards Scottish-based resources, government policy for the North coast of Scotland--an area which planners classed as ''peripheral'' but which must now accommodate extensive support facilities and service industries for the oil sites. There is also the question of relations between national and commercial interests--government versus the giant multi-national companies which took the initial gamble in the North Sea and are now responsible for the development of a resource vital to the economic well-being of Western Europe.

  16. Ecology and conservation of North American sea ducks

    Science.gov (United States)

    Savard, Jean-Pierre L.; Derksen, Dirk V.; Esler, Daniel N.; Eadie, John M.

    2015-01-01

    The past decade has seen a huge increase in the interest and attention directed toward sea ducks, the Mergini tribe. This has been inspired, in large part, by the conservation concerns associated with numerical declines in several sea duck species and populations, as well as a growing appreciation for their interesting ecological attributes. Reflecting the considerable research recently conducted on this tribe, Ecology and Conservation of North American Sea Ducks examines the 15 extant species of sea ducks from North America.

  17. Quick, Easy, and Economic Mineralogical Studies of Flooded Chalk for EOR Experiments Using Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Laura Borromeo

    2018-05-01

    Full Text Available Understanding the chalk-fluid interactions and the associated mineralogical and mechanical alterations on a sub-micron scale are major goals in Enhanced Oil Recovery. Mechanical strength, porosity, and permeability of chalk are linked to mineral dissolution that occurs during brine injections, and affect the reservoir potential. This paper presents a novel “single grain” methodology to recognize the varieties of carbonates in rocks and loose sediments: Raman spectroscopy is a non-destructive, quick, and user-friendly technique representing a powerful tool to identify minerals down to 1 µm. An innovative working technique for oil exploration is proposed, as the mineralogy of micron-sized crystals grown in two flooded chalk samples (Liége, Belgium was successfully investigated by Raman spectroscopy. The drilled chalk cores were flooded with MgCl2 for ca. 1.5 (Long Term Test and 3 years (Ultra Long Term Test under North Sea reservoir conditions (Long Term Test: 130 °C, 1 PV/day, 9.3 MPa effective stress; Ultra Long Term Test: 130 °C, varying between 1–3 PV/day, 10.4 MPa effective stress. Raman spectroscopy was able to identify the presence of recrystallized magnesite along the core of the Long Term Test up to 4 cm from the injection surface, down to the crystal size of 1–2 µm. In the Ultra Long Term Test core, the growth of MgCO3 affected nearly the entire core (7 cm. In both samples, no dolomite or high-magnesium calcite secondary growth could be detected when analysing 557 and 90 Raman spectra on the Long and Ultra Long Term Test, respectively. This study can offer Raman spectroscopy as a breakthrough tool in petroleum exploration of unconventional reservoirs, due to its quickness, spatial resolution, and non-destructive acquisition of data. These characteristics would encourage its use coupled with electron microscopes and energy dispersive systems or even electron microprobe studies.

  18. Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

    DEFF Research Database (Denmark)

    Salt, Lesley A.; Thomas, Helmuth; Prowe, Friederike

    2013-01-01

    [1] High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system...... of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive...... observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead...

  19. Pseudocollapse and rebuilding of North Sea mackerel (Scomber scombrus)

    DEFF Research Database (Denmark)

    Jansen, Teunis

    2014-01-01

    The largest observed change in mackerel (Scomber scombrus) abundance in the North Atlantic happened when the so-called “North Sea mackerel” collapsed due to overfishing. Despite protection, it has remained in a depleted state. Central to this interpretation was that the “North Sea mackerel...

  20. Mechanisms of long-term mean sea level variability in the North Sea

    Science.gov (United States)

    Dangendorf, Sönke; Calafat, Francisco; Øie Nilsen, Jan Even; Richter, Kristin; Jensen, Jürgen

    2015-04-01

    We examine mean sea level (MSL) variations in the North Sea on timescales ranging from months to decades under the consideration of different forcing factors since the late 19th century. We use multiple linear regression models, which are validated for the second half of the 20th century against the output of a state-of-the-art tide+surge model (HAMSOM), to determine the barotropic response of the ocean to fluctuations in atmospheric forcing. We demonstrate that local atmospheric forcing mainly triggers MSL variability on timescales up to a few years, with the inverted barometric effect dominating the variability along the UK and Norwegian coastlines and wind (piling up the water along the coast) controlling the MSL variability in the south from Belgium up to Denmark. However, in addition to the large inter-annual sea level variability there is also a considerable fraction of decadal scale variability. We show that on decadal timescales MSL variability in the North Sea mainly reflects steric changes, which are mostly remotely forced. A spatial correlation analysis of altimetry observations and baroclinic ocean model outputs suggests evidence for a coherent signal extending from the Norwegian shelf down to the Canary Islands. This supports the theory of longshore wind forcing along the eastern boundary of the North Atlantic causing coastally trapped waves to propagate along the continental slope. With a combination of oceanographic and meteorological measurements we demonstrate that ~80% of the decadal sea level variability in the North Sea can be explained as response of the ocean to longshore wind forcing, including boundary wave propagation in the Northeast Atlantic. These findings have important implications for (i) detecting significant accelerations in North Sea MSL, (ii) the conceptual set up of regional ocean models in terms of resolution and boundary conditions, and (iii) the development of adequate and realistic regional climate change projections.

  1. Chalk as a reservoir

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    , and the best reservoir properties are typically found in mudstone intervals. Chalk mudstones vary a lot though. The best mudstones are purely calcitic, well sorted and may have been redeposited by traction currents. Other mudstones are rich in very fine grained silica, which takes up pore space and thus...... basin, so stylolite formation in the chalk is controlled by effective burial stress. The stylolites are zones of calcite dissolution and probably are the source of calcite for porefilling cementation which is typical in water zone chalk and also affect the reservoirs to different extent. The relatively...... have hardly any stylolites and can have porosity above 40% or even 50% and thus also have relatively high permeability. Such intervals have the problem though, that increasing effective stress caused by hydrocarbon production results in mechanical compaction and overall subsidence. Most other chalk...

  2. Opportunities for suppliers in the North Sea

    International Nuclear Information System (INIS)

    D'Ancona, J.E.

    1992-01-01

    If European suppliers to the offshore industry are to prosper, it has to be on the basis of a single internationally competitive North Sea market. If we continue to talk and think in terms of a British sector, a Norwegian sector, Dutch and Danish sectors, then we will inhibit the full development of contractors and suppliers. The long term future in oilfield supplies lies in a mixed portfolio of international projects. Oil and gas exploration and development, particularly offshore, is notoriously cyclical. To survive the downturns in one market supply, companies need to have access to the upswing in others. The significance of a single North Sea market is that it presents an international arena for the best companies to demonstrate their technical and commercial abilities. Individual national sectors do not - cannot - provide that opportunity to anything like the same extent. Taking then the North Sea as a single competitive market, it represents the most important offshore area in the world at the present time, and this is likely to continue during the 1990s. The prospects of achieving a single North Sea market are discussed. (author)

  3. Report from Holland: the economics of North Sea hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Ellman, M

    1977-09-01

    The article describes how, despite huge revenues from North Sea gas, Holland is currently suffering from unemployment and its long-term prospects are poor. In light of this, Mr. Ellman discusses the implications of North Sea oil for the UK economy. He sites three distinguishable policies that the UK government could adopt in the face of the huge import saving and export creation that North Sea hydrocarbons will soon bring--sound finance, demand management, and structural modernization. (MCW)

  4. Regulation of CO2 Air Sea Fluxes by Sediments in the North Sea

    Science.gov (United States)

    Burt, William; Thomas, Helmuth; Hagens, Mathilde; Brenner, Heiko; Pätsch, Johannes; Clargo, Nicola; Salt, Lesley

    2016-04-01

    A multi-tracer approach is applied to assess the impact of boundary fluxes (e.g. benthic input from sediments or lateral inputs from the coastline) on the acid-base buffering capacity, and overall biogeochemistry, of the North Sea. Analyses of both basin-wide observations in the North Sea and transects through tidal basins at the North-Frisian coastline, reveal that surface distributions of the δ13C signature of dissolved inorganic carbon (DIC) are predominantly controlled by a balance between biological production and respiration. In particular, variability in metabolic DIC throughout stations in the well-mixed southern North Sea indicates the presence of an external carbon source, which is traced to the European continental coastline using naturally-occurring radium isotopes (224Ra and 228Ra). 228Ra is also shown to be a highly effective tracer of North Sea total alkalinity (AT) compared to the more conventional use of salinity. Coastal inputs of metabolic DIC and AT are calculated on a basin-wide scale, and ratios of these inputs suggest denitrification as a primary metabolic pathway for their formation. The AT input paralleling the metabolic DIC release prevents a significant decline in pH as compared to aerobic (i.e. unbuffered) release of metabolic DIC. Finally, long-term pH trends mimic those of riverine nitrate loading, highlighting the importance of coastal AT production via denitrification in regulating pH in the southern North Sea.

  5. Geology of the North Sea and Skagerrak

    Energy Technology Data Exchange (ETDEWEB)

    Michelsen, O. [ed.

    1995-12-31

    The Marine Geology Unit of the Department of Earth Sciences organized the second Marine Geology symposium at Aarhus University, 7-8 October 1993. The intention was to bring together people working especially with the geology of the North Sea and Skagerrak. Approximately 60 people from different Danish and Norwegian institutions attended the symposium. 28 oral presentations were given and 2 posters presented. A large range of geological topics was covered, embracing biostratigraphy, sequence stratigraphy, sedimentology and structural geology. The majority of the presentations dealt with Quaternary geology and Cenozoic sequence stratigraphy, but also Jurassic and Lower Cretaceous stratigraphy was treated. Studies from the major part of the Danish sector were presented, spanning from Bornholm to the central North Sea, and further into the Norwegian North Sea sector. (au)

  6. SeaWiFS: North Pacific Storm

    Science.gov (United States)

    2002-01-01

    An extratropical storm can be seen swirling over the North Pacific just south of Alaska. This SeaWiFS image was collected yesterday at 23:20 GMT. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  7. Experimental study and mechanical modelling of the effects of water-driving in an oil saturated chalk. Application to the petroleum industry; Etude experimentale et modelisation mecanique des effets du balayage a l'eau dans une craie saturee d'huile. Application a l'industrie petroliere

    Energy Technology Data Exchange (ETDEWEB)

    Mata, C.

    2001-01-01

    The production of hydrocarbons may sometimes lead to compaction of the oil-reservoir layers with substantial collapse of the soil surface; this mechanism is usually mentioned as Subsidence. Classical remedy to this problem is to sustain the fluid pressure with the help of water injection. However, in presence of high porosity chalk (porosity > 30%), this technique does not give effective results: the subsidence rate at North Sea reservoirs (Ekofisk field), after injection, has remained unchanged. Some justify the subsistence in the chalk as caused by phenomena of dissolution of the carbonates; others think it is connected to the destruction of capillary menisci. In this research, we follow this second approach. This study is finalized to a better understanding of the compaction mechanisms in pure carbonates when water is injected. This is done by proposing -in micro-scale first and in macro-scale after- a physical model that agrees with empirical observations. In order to meet this target, IFP skills and experience in physical and chemical measurements (taken before, after and during mechanical tests) have proficiently joined ENPC laboratory (CERMMO) knowledge of micro and macro modelling. The soft rock studied is a Paris basin's white chalk (Craie de Guerville). Its physical and chemical characterisation (i.e.: silica content, porosity, permeability) is very similar to North Sea chalk, but Guerville chalk has never been in contact with oil and generally it crops out of the ground surface. Strength parameters of this rock have been first determined by standard triaxial tests. Three different saturation configurations have been examined: dry, fully oil-saturated and fully water-saturated. As literature clearly state, dry chalk is stronger than oil saturated chalk and the first two are largely stronger than water saturated chalk. Therefore uniaxial strain water injection tests have been performed on oil saturated samples. Results, coupled with previous physical

  8. Two centuries of extreme events over the Baltic Sea and North Sea regions

    Science.gov (United States)

    Stendel, Martin; den Besselaar Else, van; Abdel, Hannachi; Jaak, Jaagus; Elizabeth, Kent; Christiana, Lefebvre; Gudrun, Rosenhagen; Anna, Rutgersson; Frederik, Schenk; der Schrier Gerard, van; Tim, Woolings

    2017-04-01

    Two centuries of extreme events over the Baltic Sea and North Sea regions In the framework of the BACC 2 (for the Baltic Sea) and NOSCCA projects (for the North Sea region), studies of past and present variability and changes in atmospheric variables within the North Sea region over the instrumental period (roughly the past 200 years) have been investigated. Findings on trends in temperature and precipitation have already been presented. Here we focus on data homogeneity issues and examine how reliable reanalyses are in this context. Unlike most other regions in the world, there is a wealth of old observations available for the Baltic and North Sea regions, most of it in handwritten form in meteorological journals and other publications. These datasets need to be carefully digitised and homogenized. For this, a thorough quality control must be applied; otherwise the digitised datasets may prove useless or even counterproductive. We present evidence that this step cannot be conducted without human interference and thus cannot be fully automated. Furthermore, inhomogeneities due to e.g. instrumentation and station relocations need to be addressed. A wealth of reanalysis products is available, which can help detect such inhomogeneities in observed time series, but at the same time are prone to biases and/or spurious trends themselves e.g. introduced by changes in the availability and quality of the underlying assimilated data. It therefore in general remains unclear in how far we can simulate the pre-satellite era with respect to homogeneity with reanalyses based only on parts of the observing system. Extreme events and changes in extreme situations are more important and of greater (societal) significance than changes in mean climate. However, changes in extreme weather events are difficult to assess not only because they are, per definition, rare events, but also due to the homogeneity issues outlined above. Taking these into account, we present evidence for changes

  9. Slope failure of chalk channel margins

    DEFF Research Database (Denmark)

    Gale, A.; Anderskouv, Kresten; Surlyk, Finn

    2015-01-01

    provide evidence for recurring margin collapse of a long-lived Campanian channel. Compressionally deformed and thrust chalk hardgrounds are correlated to thicker, non-cemented chalk beds that form a broad, gentle anticline. These chalks represent a slump complex with a roll-over anticline of expanded, non......-cemented chalk in the head region and a culmination of condensed hardgrounds in the toe region. Observations strongly suggest that the slumping represents collapse of a channel margin. Farther northwards, the contemporaneous succession shows evidence of small-scale penecontemporaneous normal faulting towards...

  10. Wind fluctuations over the North Sea

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Pinson, Pierre; Giebel, Gregor

    2011-01-01

    Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms. The Hil......Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms...

  11. Tender moments in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Fox, C

    1991-04-01

    Described is tender-assisted drilling (TAD) on the UK North Sea Gannet field. The Gannet field is developed by Shell UK Exploration and Production (Shell Expro). In March 1990, Shell Expro awarded Sedco Forex the design and engineering contract to convert the semisubmersible drilling rig Sedco 704 into the Gannet TSV (Tender Support Vessel). The only semisubmersible TSV operation so far to have completed drilling in the North Sea has been in the Norwegian sector. The Odin field, operated by Esso Norge a/s, was developed using the converted drilling rig Treasure Hunter. 1 fig., 1 ill., 3 refs.

  12. North Sea ecosystem change from swimming crabs to seagulls.

    Science.gov (United States)

    Luczak, C; Beaugrand, G; Lindley, J A; Dewarumez, J-M; Dubois, P J; Kirby, R R

    2012-10-23

    A recent increase in sea temperature has established a new ecosystem dynamic regime in the North Sea. Climate-induced changes in decapods have played an important role. Here, we reveal a coincident increase in the abundance of swimming crabs and lesser black-backed gull colonies in the North Sea, both in time and in space. Swimming crabs are an important food source for lesser black-backed gulls during the breeding season. Inhabiting the land, but feeding mainly at sea, lesser black-backed gulls provide a link between marine and terrestrial ecosystems, since the bottom-up influence of allochthonous nutrient input from seabirds to coastal soils can structure the terrestrial food web. We, therefore, suggest that climate-driven changes in trophic interactions in the marine food web may also have ensuing ramifications for the coastal ecology of the North Sea.

  13. The importance of North Sea gas to European energy supply

    International Nuclear Information System (INIS)

    Probert, R.

    1992-01-01

    Natural gas can, of course, be transported over very long distances but, because of the economics of gas transmission, its impact is most often local. This has certainly been the case with North Sea gas, which has clearly contributed significantly to European energy supply and will continue to do so for some time to come. The historical importance of the discovery of gas in the North Sea has been that it has enabled natural gas industries to grow rapidly in North West Europe. Without North Sea gas and Dutch gas it is difficult to see how town gas would have been replaced in North West Europe. Certainly, a much smaller natural gas industry would have emerged. North Sea gas has inevitably had the greatest impact on gas markets in the countries of the European Community and this will remain the case in future. Nevertheless, it is inevitable that gas will, in future, flow across more national boundaries than in the past, and that North Sea gas will have an important part to play in meeting the Central European demand for competitively priced, secure supplies. This paper discusses the United Kingdom market for gas and future demand both in the United Kingdom and more widely in Europe. An examination of the availability of gas supplies from the North Sea suggests that it is unlikely that there will be a surplus of gas for export from the United Kingdom continental shelf. Norway will remain the main source of exports, with the Netherlands also in a strong position. Transportation and political aspects are also considered. (author)

  14. Nickel adsorption on chalk and calcite

    DEFF Research Database (Denmark)

    Belova, Dina Alexandrovna; Lakshtanov, Leonid; Carneiro, J.F.

    2014-01-01

    Nickel uptake from solution by two types of chalk and calcite was investigated in batch sorption studies. The goal was to understand the difference in sorption behavior between synthetic and biogenic calcite. Experiments at atmospheric partial pressure of CO2, in solutions equilibrated with calcite...... = - 1.12 on calcite and log KNi = - 0.43 and - 0.50 on the two chalk samples. The study confirms that synthetic calcite and chalk both take up nickel, but Ni binds more strongly on the biogenic calcite than on inorganically precipitated, synthetic powder, because of the presence of trace amounts...... of polysaccharides and clay nanoparticles on the chalk surface....

  15. Jurassic domes in the North Sea - northern North Atlantic region

    Energy Technology Data Exchange (ETDEWEB)

    Surlyk, F. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark)

    1996-12-31

    The stratigraphic and tectonic evolution of the Jurassic of East Greenland, the Norwegian Shelf and the North Sea is remarkably similar. A major Middle Jurassic unconformity occurs in all three areas. In the North Sea it is commonly termed the `Mid-Cimmerian Unconformity` and is characterized by progressive truncation of the underlying section towards a centre at the triple junction between the Central Graben, Viking Graben and Moray Firth. Strata above the unconformity show a progressive Late Aalenian-Early Kimmeridgian onlap in the same direction. These relations have been interpreted as caused by Early Jurassic uplift and of a major thermal dome in the central North Sea, followed by Medial and Late Jurassic rifting, erosion, deflation and transgression of the dome. The East Greenland unconformity shows progressive truncation of underlying strata from south to north, and Bajocian to Callovian onlap in the same direction. The same pattern seems to be developed on the conjugate Norwegian margin. This suggests the possibility that the three unconformities have similar causes for their development. It is proposed that major rift domes formed in the Central North Sea and in the Greenland-Norway seaway in Early Jurassic times. The domes were eroded and gradually deflated during Medial Jurassic times and were finally submerged by the Late Oxfordian-Kimmeridgian. They were associated with volcanism and rifting which was delayed with respect to dome initiation. Roughly contemperaneous domes were present west of Britain, north of the Porcupine Seabight, and in Scania, southern Sweden, as reflected by development of asymmetrical unconformities showing progressive truncation of underlying strata, onlap of overlying Jurassic strata, and associated intrusive and extrusive volcanism. The domes are related to impingement of the heads of transient mantle plumes at the base of the lithosphere. The associated unconformities are thus of non-eustatic nature. Domal uplift and

  16. Illicit drugs and their metabolites in 36 rivers that drain into the Bohai Sea and north Yellow Sea, north China.

    Science.gov (United States)

    Wang, De-Gao; Zheng, Qiu-Da; Wang, Xiao-Ping; Du, Juan; Tian, Chong-Guo; Wang, Zhuang; Ge, Lin-Ke

    2016-08-01

    Illicit drugs and their metabolites have recently been recognized as an emerging group of contaminants due to their potential ecotoxicological impact in aquatic ecosystems. To date, information on the occurrence of these compounds in the aquatic environment of China remains limited. In this study, we collected surface water samples from 36 rivers in north China that discharge into the Bohai Sea and north Yellow Sea and measured the concentrations of amphetamine-like compounds, ketamines, cocainics, and opioids. The occurrence and spatial patterns of these substances show significant differences between the rivers and regions. Two designer drugs, methamphetamine (METH) and ketamine (KET), were the most abundant compounds detected in the entire set of samples (detection frequency of 92 and 69 %). The concentrations of METH and KET ranged from illicit drugs consumed in China. The high concentrations of these illicit drugs and their metabolites were found in areas that have a high population density. The riverine input of total illicit drugs into the Bohai Sea and north Yellow Sea was estimated to be in the range of 684 to 1160 kg per year.

  17. Modeling the buoyancy-driven Black Sea Water outflow into the North Aegean Sea

    Directory of Open Access Journals (Sweden)

    Nikolaos Kokkos

    2016-04-01

    Full Text Available A three-dimensional numerical model was applied to simulate the Black Sea Water (BSW outflux and spreading over the North Aegean Sea, and its impact on circulation and stratification–mixing dynamics. Model results were validated against satellite-derived sea surface temperature and in-situ temperature and salinity profiles. Further, the model results were post-processed in terms of the potential energy anomaly, ϕ, analyzing the factors contributing to its change. It occurs that BSW contributes significantly on the Thracian Sea water column stratification, but its signal reduces in the rest of the North Aegean Sea. The BSW buoyancy flux contributed to the change of ϕ in the Thracian Sea by 1.23 × 10−3 W m−3 in the winter and 7.9 × 10−4 W m−3 in the summer, significantly higher than the corresponding solar heat flux contribution (1.41 × 10−5 W m−3 and 7.4 × 10−5 W m−3, respectively. Quantification of the ϕ-advective term crossing the north-western BSW branch (to the north of Lemnos Island, depicted a strong non-linear relation to the relative vorticity of Samothraki Anticyclone. Similar analysis for the south-western branch illustrated a relationship between the ϕ-advective term sign and the relative vorticity in the Sporades system. The ϕ-mixing term increases its significance under strong winds (>15 m s−1, tending to destroy surface meso-scale eddies.

  18. Compaction of microfossil and clay-rich chalk sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2001-01-01

    The aim of this study was to evaluate the role of microfossils and clay in the compaction of chalk facies sediments. To meet this aim, chalk sediments with varying micro texture were studied. The sediments have been tested uniaxially confined in a stainless-steel compaction cell. The sediments are......: 1) Pure carbonate chalk with mudstone texture from Stevns Klint (Denmark), 2) Relatively pure chalk sediments with varying content of microfossils from the Ontong Java Plateau (Western Pacific), 3) Clay-rich chalk and mixed sediments from the Caribbean. The tested samples were characterised...

  19. Estimating the effective nitrogen import: An example for the North Sea-Baltic Sea boundary

    Science.gov (United States)

    Radtke, H.; Maar, M.

    2016-10-01

    Semienclosed water bodies such as the Baltic Sea are prone to eutrophication problems. If local nutrient abatement measures are taken to tackle these problems, their success may be limited if a strong nutrient exchange with the adjacent waters exists. The quantification of this exchange is therefore essential to estimate its impact on the ecosystem status. At the example of the Baltic Sea and the North Sea, we illustrate that neither gross transports nor net transports of nutrients have a strong informative value in this context. Instead, we define an "effective import" as the import of nutrients which have not been inside the Baltic Sea before and estimate it in an ecological model with a nutrient-tagging technique. This effective import of bioreactive nitrogen from the Skagerrak to the Kattegat amounts to 103 kt/yr; from Kattegat to Belt Sea it is 54 kt/yr. The nitrogen exchange is therefore 30% stronger than other estimates, e.g., based on import in the deep water, suggest. An isolated view on the Baltic Sea and the North Sea in terms of eutrophication, as it is practiced in management today, is therefore questionable. Nitrogen imported from the North Sea typically spreads eastward up to the Bornholm Basin but can be transported into the deep waters of the Gotland Basin during Major Baltic Inflows in a significant amount.

  20. Terrestrial dissolved organic matter distribution in the North Sea.

    Science.gov (United States)

    Painter, Stuart C; Lapworth, Dan J; Woodward, E Malcolm S; Kroeger, Silke; Evans, Chris D; Mayor, Daniel J; Sanders, Richard J

    2018-07-15

    The flow of terrestrial carbon to rivers and inland waters is a major term in the global carbon cycle. The organic fraction of this flux may be buried, remineralized or ultimately stored in the deep ocean. The latter can only occur if terrestrial organic carbon can pass through the coastal and estuarine filter, a process of unknown efficiency. Here, data are presented on the spatial distribution of terrestrial fluorescent and chromophoric dissolved organic matter (FDOM and CDOM, respectively) throughout the North Sea, which receives organic matter from multiple distinct sources. We use FDOM and CDOM as proxies for terrestrial dissolved organic matter (tDOM) to test the hypothesis that tDOM is quantitatively transferred through the North Sea to the open North Atlantic Ocean. Excitation emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) revealed a single terrestrial humic-like class of compounds whose distribution was restricted to the coastal margins and, via an inverse salinity relationship, to major riverine inputs. Two distinct sources of fluorescent humic-like material were observed associated with the combined outflows of the Rhine, Weser and Elbe rivers in the south-eastern North Sea and the Baltic Sea outflow to the eastern central North Sea. The flux of tDOM from the North Sea to the Atlantic Ocean appears insignificant, although tDOM export may occur through Norwegian coastal waters unsampled in our study. Our analysis suggests that the bulk of tDOM exported from the Northwest European and Scandinavian landmasses is buried or remineralized internally, with potential losses to the atmosphere. This interpretation implies that the residence time in estuarine and coastal systems exerts an important control over the fate of tDOM and needs to be considered when evaluating the role of terrestrial carbon losses in the global carbon cycle. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  1. Worldwide market forces threaten North Sea wealth

    Energy Technology Data Exchange (ETDEWEB)

    Booth, D

    1977-01-01

    The challenges that the petroleum industry faces in winning all the oil resources in the North Sea are reviewed. All these hydrocarbons that will soon sustain governments, bolster the standard of living, and bring profits to investors will one day be gone, perhaps. The author says, ''if demand for oil continues to rise by a few percent each year for the next 25 years the prospect of the North Sea drained of its riches is real. Even if Britain makes no more demands on it than those needs of today, the global concept of the oil business will mean that other markets will place the North Sea reserves at risk of exhaustion. Two major factors affect this assumption: market forces and government-implemented depletion rates.'' After explaining these two assumptions, the author graphically portrays what life will be like when petrol becomes a luxury item. It is forgotten that the hydrocarbons are being consumed in a lifetime, when it took several millions of years to put them together. (MCW)

  2. Groundwater recharge dynamics in unsaturated fractured chalk: a case study

    Science.gov (United States)

    Cherubini, Claudia; Pastore, Nicola; Giasi, Concetta I.; Allegretti, Nicolaetta M.

    2016-04-01

    The heterogeneity of the unsaturated zone controls its hydraulic response to rainfall and the extent to which pollutants are delayed or attenuated before reaching groundwater. It plays therefore a very important role in the recharge of aquifers and the transfer of pollutants because of the presence of temporary storage zones and preferential flows. A better knowledge of the physical processes in the unsaturated zone would allow an improved assessment of the natural recharge in a heterogeneous aquifer and of its vulnerability to surface-applied pollution. The case study regards the role of the thick unsaturated zone of the Cretaceous chalk aquifer in Picardy (North of France) that controls the hydraulic response to rainfall. In the North Paris Basin, much of the recharge must pass through a regional chalk bed that is composed of a porous matrix with embedded fractures. Different types of conceptual models have been formulated to explain infiltration and recharge processes in the unsaturated fractured rock. The present study analyses the episodic recharge in fractured Chalk aquifer using the kinematic diffusion theory to predict water table fluctuation in response to rainfall. From an analysis of the data, there is the evidence of 1) a seasonal behavior characterized by a constant increase in the water level during the winter/spring period and a recession period, 2) a series of episodic behaviors during the summer/autumn. Kinematic diffusion models are useful for predict preferential fluxes and dynamic conditions. The presented approach conceptualizes the unsaturated flow as a combination of 1) diffusive flow refers to the idealized portion of the pore space of the medium within the flow rate is driven essentially by local gradient of potential; 2) preferential flow by which water moves across macroscopic distances through conduits of macropore length.

  3. Chalk effect on PVC cross-linking under irradiation

    International Nuclear Information System (INIS)

    Chudinova, V.V.; Guzeev, V.V.; Mozzhukhin, V.B.; Pomerantseva, Eh.G.; Nozrina, F.D.; Zhil'tsov, V.V.; Zubov, V.P.

    1994-01-01

    Effect of nonmodified and modified chalk on curing degree of polymer matrix was studied under-irradiation of PVC-compositions. Films of the compositions (100 mass part 7 PVC, 0-100 mas.part of chalk, 2.5 - lead sulfate, 1.5 - lead stearate and 0.3 - glycerin) were irradiated up to absorbed dose 0.1 MGy in an inert medium. Content of gel-fraction after boiling in THF was determined with use of IR spectroscopy. It was established, that intensive dehydrochlorination and polymer curing took place on chalk particle surface. Network fixed strongly chalk particles. However, chalk inhibited processes of dehydrochlorination and PVC curing, increasing amount of noncured PVC in polymer matrix

  4. Mechanisms controlling the air–sea CO2 flux in the North Sea

    NARCIS (Netherlands)

    Prowe, A.E.F.; Thomas, Helmuth; Pätsch, Johannes; Kühn, Wilfried; Bozec, Yann; Schiettecatte, Laure-Sophie; Borges, Alberto V.; Baar, Hein J.W. de; Paetsch, J; Kuehn, W

    2009-01-01

    The mechanisms driving the air–sea exchange of carbon dioxide (CO2) in the North Sea are investigated using the three-dimensional coupled physical–biogeochemical model ECOHAM (ECOlogical-model, HAMburg). We validate our simulations using field data for the years 2001–2002 and identify the controls

  5. Chalk Formations as Natural Barriers towards Radionuclide Migration

    DEFF Research Database (Denmark)

    Pedersen, Walther Batsberg; Carlsen, Lars; Jensen, Bror Skytte

    1985-01-01

    A series of chalk samples from the cretaceous formation overlying the Erslev salt dome have been studied in order to establish permeabilities, porosities, dispersion-, diffusion-, and sorption characteristics of the chalk. The chalk was found to be porous (∊≈0.4), however, of rather low...

  6. Loss of sea ice during winter north of Svalbard

    Directory of Open Access Journals (Sweden)

    Ingrid H. Onarheim

    2014-06-01

    Full Text Available Sea ice loss in the Arctic Ocean has up to now been strongest during summer. In contrast, the sea ice concentration north of Svalbard has experienced a larger decline during winter since 1979. The trend in winter ice area loss is close to 10% per decade, and concurrent with a 0.3°C per decade warming of the Atlantic Water entering the Arctic Ocean in this region. Simultaneously, there has been a 2°C per decade warming of winter mean surface air temperature north of Svalbard, which is 20–45% higher than observations on the west coast. Generally, the ice edge north of Svalbard has retreated towards the northeast, along the Atlantic Water pathway. By making reasonable assumptions about the Atlantic Water volume and associated heat transport, we show that the extra oceanic heat brought into the region is likely to have caused the sea ice loss. The reduced sea ice cover leads to more oceanic heat transferred to the atmosphere, suggesting that part of the atmospheric warming is driven by larger open water area. In contrast to significant trends in sea ice concentration, Atlantic Water temperature and air temperature, there is no significant temporal trend in the local winds. Thus, winds have not caused the long-term warming or sea ice loss. However, the dominant winds transport sea ice from the Arctic Ocean into the region north of Svalbard, and the local wind has influence on the year-to-year variability of the ice concentration, which correlates with surface air temperatures, ocean temperatures, as well as the local wind.

  7. Situation in the sea area between the North Sea and the Baltic Sea. Situationen i havsomraadet mellan Nordsjoen och Oestersjoen

    Energy Technology Data Exchange (ETDEWEB)

    Dybern, B.I.; Soederstroem, J.; Thorell, L.

    1984-01-01

    Due to the special topographical and hydrological features the seas surrounding Sweden are very sensitive to both natural changes and changes caused by man. The sea area between the North Sea and the Baltic Sea has come into focus during the last few decades due to problems with pollution and its impact on the ecosystems and to overfishing of some commer- cially important species. In order to elucidate the present situation from the Swedish viewpoint, the National Board of Fisheries, the National Environment Protection Board and the County Council of the County Goeteborg and Bohyslaen arranged a Symposium on the Situation in the Sea Area between the North Sea and the Baltic Sea in Goeteborg, 14-16 March, 1983. This volume contains lectures given at that Symposium. In most cases there are English summaries and English translations of texts to figures and tables.

  8. Environmental isotope studies related to groundwater flow and saline encroachment in the chalk aquifer of Lincolnshire, England

    International Nuclear Information System (INIS)

    Lloyd, J.W.; Howard, K.W.F.

    1978-01-01

    The isotopes of tritium and carbon are used to study part of the North Lincolnshire Chalk aquifer in England. The tritium data support the view that the aquifer is a thin fissure system and indicate that some changes in flow direction have occurred due to recent abstraction. The data are also consistent with other chemical data in elucidating groundwater entering the Chalk from deeper aquifers. Carbon isotopes are used to distinguish between saline water bodies and suggest that saline water was entrapped within the aquifer in the Eemian and Flandrian stages of the Pleistocene. (orig.) [de

  9. Modelling the atmospheric transport of trace metals from Europe to the North Sea and the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, G; Weber, H; Grassl, H [GKSS-Forschungszentrum Geesthacht G.m.b.H., Geesthacht-Tesperhude (Germany, F.R.). Inst. fuer Physik

    1989-01-01

    Within the framework of a research contract with the German Federal Environmental Agency the long range transport of trace metals over Europe and the deposition of trace metals into the North Sea and the Baltic Sea are estimated using the EMEP- (European Monitoring and Evaluation Programme) trajectory model. The methodology for the model calculations is explained. Preliminary results for the total deposition of lead into the North Sea and the Baltic Sea show, that the calculated values are lower than previous estimates based on extrapolations from measurements at coastal sites and ship measurements in the southern Baltic Sea, respectively. (orig.).

  10. Sediment volume in the north polar sand seas of Mars

    International Nuclear Information System (INIS)

    Lancaster, N.; Greeley, R.

    1990-01-01

    Data from studies of the cross-sectional area of terrestrial transverse dunes have been combined with maps of dune morphometry derived from Viking orbiter images to generate new estimates of sediment thickness and dune sediment volume in the north polar sand seas of Mars. A relationship between dune spacing and equivalent sediment thickness (EST) was developed from field data on Namibian and North American dunes and was applied to data on dune spacing and dune cover measured on Viking orbiter images to generate maps of dune sediment thickness for Martian north polar sand seas. There are four major sand seas in the north polar region of Mars, covering an area of 6.8 x 10 5 km 2 . Equivalent sediment thickness ranges between 0.5 and 6.1 m with a mean of 1.8 m. The sand seas contain a total of 1158 km 3 of dune sediment, which may have been derived by erosion of polar layered deposits and concentrated in its present location by winds that change direction seasonally

  11. Adsorption Properties of Chalk Reservoir Materials

    DEFF Research Database (Denmark)

    Okhrimenko, Denis

    /gas adsorption properties of synthetic calcium carbonate phases (calcite, vaterite and aragonite) with chalk, which is composed of biogenic calcite (>98%). In combination with data from nanotechniques, the results demonstrate the complexity of chalk behavior and the role of nanoscale clay particles. The results...

  12. The importance of North Sea oil to European energy supply

    International Nuclear Information System (INIS)

    Bauw, R. De

    1992-01-01

    There is no doubt about the importance of North Sea oil to the energy supply of the European Community. One might however be used to it and forget about the nature and the size of its impact on our economies. Firstly, this paper intends to estimate this impact - past, present and future. Secondly, a more qualitative approach will explore possible consequences of the implementation of the internal market for North Sea oil. Thirdly, the assistance given by the Community to innovative technologies which enabled North Sea oil to contribute, under better economic conditions and within a safer environment, to our supply is recalled. And finally, some remarks on energy policy form an EC perspective, are offered. (author)

  13. Emissions from oil platforms in the North Sea

    International Nuclear Information System (INIS)

    Kanowski, S.

    1991-01-01

    When oil and gas are extracted from below the sea bed, emissions generally occur drilling and extraction and when offshore installations are abandoned. The sources of such emissions are the drilling fluids which contain many chemicals, cuttings, extracted hydrocarbons, substances released as a result of accidents, and the improper disposal of substances used in drilling and production. Platforms are regarded as land-based installations. Regulations to limit emissions have been put into effect within the scope of the Paris Convention on the protection of the North Sea and the North-East Atlantic. (orig.) [de

  14. Coastal Erosion and Flooding Hazards on the North Sea Coast at Thyboron, Denmark

    DEFF Research Database (Denmark)

    Sørensen, Per; Sørensen, Carlo Sass; Nielsen, Peter

    Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s coun...... counteracted the natural erosion in the upper profile on the North Sea coast where the alongshore sediment transport converges towards the channel and deposits up to 1 million m3/y on the flood tidal delta inside the fiord, Figure 1.......Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s...

  15. Spatial differences in growth of lesser sandeel in the North Sea

    DEFF Research Database (Denmark)

    Rindorf, Anna; Wright, Peter J.; Jensen, Henrik

    2016-01-01

    Lesser sandeel, Ammodytes marinus, is a key prey to a variety of North Sea predators, including species such as single load seabirds which are highly sensitive to prey size and condition. Whilst differences in weight at age across the North Sea have been investigated previously, the scale and cause...... of this variation as well as the potential link to spatial differences in predator performance remains unknown. This study presents an analysis of spatial patterns in length and condition of the lesser sandeel in the North Sea and the relationship of these with physical and biological factors. Both mean length...... considerably both spatially and temporally, resulting in 4 fold and 1.9 fold variations in the number of sandeels required to obtain a specific weight, respectively. Hence, the value of sandeel as prey to single load predators varies considerably with values in central and northeastern North Sea being...

  16. Microbial biogeography of the North Sea during summer

    NARCIS (Netherlands)

    Brandsma, J.; Martínez Martínez, J.; Slagter, H.A.; Evans, C.; Brussaard, C.P.D.

    2013-01-01

    Micro-organisms are vital for the functioning of all food webs and are the major drivers of the global biogeochemical cycles. The microbial community compositions and physicochemical conditions of the different water masses in the North Sea, a biologically productive sea on the northwestern European

  17. Self Compacting Concrete with Chalk Filler

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    2007-01-01

    Utilisation of Danish chalk filler has been investigated as a means to produce self compacting concrete (SCC) at lower strength levels for service in non aggressive environments. Stable SCC mixtures were prepared at chalk filler contents up to 60% by volume of binder to yield compressive strengths...

  18. Sea surface temperatures and salinities from platforms in the Barents Sea, Sea of Japan, North Atlantic Ocean, Philippine Sea, Red Sea, and the South China Sea (Nan Hai) from 1896-1950 (NODC Accession 0000506)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface temperatures and salinities were collected in the Barents Sea, Sea of Japan, North Atlantic Ocean, Philippine Sea, Red Sea, and South China Sea (Nan Hai)...

  19. North Sea mackerel egg survey: dutch participation may and June 2011

    NARCIS (Netherlands)

    Damme, van C.J.G.

    2012-01-01

    Every three years an international North Sea survey is carried out by two European institutes, Institute for Marine Research (IMR) from Norway and Institute for Marine Resources and Ecosystem Studies (IMARES) from the Netherlands, to monitor the spatial and seasonal distribution of North Sea

  20. Optical measurements in the North Sea-Baltic Sea transition zone. I. On the origin of the deep water in the Kattegat

    Science.gov (United States)

    Højerslev, N. K.; Holt, N.; Aarup, T.

    1996-08-01

    In the North Sea-Baltic Sea region, several studies have shown that yellow substance can be treated as a quasi-conservative parameter that is negatively correlated with salinity. A review of more than 5000 historic and recently gathered yellow substance absorption and salinity measurements from the transition zone between the North Sea and the Baltic Sea have been analyzed for the purpose of water mass identification. Salinity-yellow substance scatter plots show that three water masses can be identified in the area: (1) North Sea water (high salinity, low yellow substance content); (2) Baltic Sea water (low salinity, intermediate-high yellow substance content); and (3) German Bight/Southern North Sea water (intermediate-high salinity, high yellow substance content). Based on the volume flow estimates used in a two-layer box-model of the Kattegat (Jørgensen, Continental Shelf Research, 12, 103-114, 1992) and conservation of yellow substance, it is argued that the long-term average composition of the bottom layer inflow to the Kattegat from the Skagerrak consists of about 90% North Sea/Atlantic water and 10% German Bight/Southern North Sea water. The German Bight content estimate is substantially lower than the ones given in earlier studies (50-67%) and implies that the Jutland Coastal Current only has a small impact on the water quality of the Kattegat.

  1. Regionalization of climate model results for the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Kauker, F. [Alfred-Wegener-Institut fuer Polar- und Meeresforschung, Bremerhaven (Germany); Storch, H. von [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

    2000-07-01

    A dynamical downscaling for the North Sea is presented. The numerical model used for the study is the coupled ice-ocean model OPYC. In a hindcast of the years 1979 to 1993 it was forced with atmospheric forcing of the ECMWF reanalysis. The models capability in simulating the observed mean state and variability in the North Sea is demonstrated by the hindcast. Two time scale ranges, from weekly to seasonal and the longer-than-seasonal time scales are investigated. Shorter time scales, for storm surges, are not captured by the model formulation. The main modes of variability of sea level, sea-surface circulation, sea-surface temperature, and sea-surface salinity are described and connections to atmospheric phenomena, like the NAO, are discussed. T106 ''time-slice'' simulations with a ''2 x CO{sub 2}'' horizon are used to estimate the effects of a changing climate on the shelf sea ''North Sea''. The ''2 x CO{sub 2}'' changes in the surface forcing are accompanied by changes in the lateral oceanic boundary conditions taken from a global coupled climate model. For ''2 x CO{sub 2}'' the time mean sea level increases up to 25 cm in the German Bight in the winter, where 15 cm are due to the surface forcing and 10 cm due to thermal expansion. This change is compared to the ''natural'' variability as simulated in the ECMWF integration and found to be not outside the range spanned by it. The variability of sea level on the weekly-to-seasonal time-scales is significantly reduced in the scenario integration. The variability on the longer-than-seasonal time-scales in the control and scenario runs is much smaller then in the ECMWF integration. This is traced back to the use of ''time-slice'' experiments. Discriminating between locally forced changes and changes induced at the lateral oceanic boundaries of the model in the circulation and

  2. Changes in size and trends of North American sea duck populations associated with North Pacific oceanic regime shifts

    Science.gov (United States)

    Flint, Paul L.

    2013-01-01

    Broad-scale multi-species declines in populations of North American sea ducks for unknown reasons is cause for management concern. Oceanic regime shifts have been associated with rapid changes in ecosystem structure of the North Pacific and Bering Sea. However, relatively little is known about potential effects of these changes in oceanic conditions on marine bird populations at broad scales. I examined changes in North American breeding populations of sea ducks from 1957 to 2011 in relation to potential oceanic regime shifts in the North Pacific in 1977, 1989, and 1998. There was strong support for population-level effects of regime shifts in 1977 and 1989, but little support for an effect of the 1998 shift. The continental-level effects of these regime shifts differed across species groups and time. Based on patterns of sea duck population dynamics associated with regime shifts, it is unclear if the mechanism of change relates to survival or reproduction. Results of this analysis support the hypothesis that population size and trends of North American sea ducks are strongly influenced by oceanic conditions. The perceived population declines appear to have halted >20 years ago, and populations have been relatively stable or increasing since that time. Given these results, we should reasonably expect dramatic changes in sea duck population status and trends with future oceanic regime shifts.

  3. Regional cenozoic uplift and subsidence events in the southeastern North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Jordt, H.

    1995-12-31

    The Paleocene topography of the Fennoscandian Shield is indicated by outbuilding towards the Central Trough and the Ringkoebing-Fyn High. From Eocene until Pliocene time three events of relative vertical movements are indicated by changes in outbuilding directions and reflection termination patterns in the central North Sea. The firs event of uplift was in the Eocene and resulted in relative uplift of the Mid North Sea High and contemporary subsidence east of it, indicated by a change in outbuilding from north to west. A second event of uplift is indicated to the north of the study area at the Eocene-Oligocene boundary by renewed southward outbuilding in the Norwegian-Danish Basin. In Miocene until Early Pliocene time a relatively stationary, almost east-west striking, basin margin was probably located to the north along the Tornquist Zone as indicated by the continued outbuilding towards the Ringkoebing-Fyn High. A third event of relative uplift is indicated east of the study area by changes in the Pliocene outbuilding pattern. After the first event of uplift it appears that the deepest parts of the Eocene North Sea Basin was located more easterly than the deepest part are today. Apparently the two latest uplift events north and east of the study area were related to movements of, or along the Tornquist Zone or to regional uplift of the Fennoscandian Shield finally resulting in the present-day configuration of the North Sea. (au) 11 refs.

  4. Why is the North Sea West of Us?

    DEFF Research Database (Denmark)

    Gammeltoft, Peder

    2016-01-01

    . Occurrences of sea names such as the North Sea are examined and analysed to see how they spread from an original one-language form to exist in multiple languages, and analyses them from a linguistic, geographic and nautical perspective. It is found that Seas or bodies of water in stretches of sea are named......This article focuses on the motivations behind sea-naming, by means of examples from Europe but also elsewhere. Why do certain sea names become dominant while others retract into local forms or simply die out? The article takes us back in time to the early days of map-making and, indeed, earlier...

  5. The Potential for Wave Energy in the North Sea

    DEFF Research Database (Denmark)

    Sørensen, H. C.; Chozas, Julia Fernandez

    2010-01-01

    The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost ...... is resulting in a prediction of a yearly production of 23TWh; the latter is estimating a yearly production of 77TWh. This equals to 6% of the electricity demand around the North Sea, where the annual electricity consumption is about 1,300TWh.......The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost...... as in the Atlantic and the distance to shore relatively long compared to sites with good wave climate like Ireland, Portugal, Spain and the west coast of UK. The increasing activities within offshore wind in the North Sea and the attempt to build a super grid connecting the wind sites with the major consumers around...

  6. Atmospheric input of trace substances into the North Sea and the Baltic Sea. Stoffeintrag in Nord- und Ostsee ueber die Atmosphaere

    Energy Technology Data Exchange (ETDEWEB)

    Grassl, H; Eppel, D; Petersen, G; Schneider, B; Weber, H; Gandrass, J; Reinhardt, K H; Wodarg, D; Fliess, J

    1989-01-01

    The concentrations and deposition of atmospheric trace substances were measured over the Kiel Bight and the Southern North Sea. A European longrange-transport model was used to calculate the atmospheric concentrations of trace metals and their deposition into the North Sea and the Baltic Sea. Natural and anthropogenic emitted element concentrations could be separated definitely by the measurements, and preferred transport directions of anthropogenic contributions could be found. Concentrations measured over the North Sea could be related to the surrounding emission areas by airmass trajectory analyses. The deposition measurements show that the main removal process is due to deposition by precipitation. Calculated and measured concentrations at several receptor points agreed well. The model results confirm the dominating role of wet deposition. It could be shown that extrapolations from measurements at coastal stations to the whole sea area tend to overestimate the total deposition into North Sea and Baltic Sea. (orig.) With 78 refs., 26 tabs., 85 figs.

  7. First report of the planktonic copepod Oithona davisae in the northern Wadden Sea (North Sea): Evidence for recent invasion?

    Science.gov (United States)

    Cornils, Astrid; Wend-Heckmann, Britta

    2015-06-01

    In October 2010, specimens of Oithona were taken from the List Tidal Basin in the northern Wadden Sea (North Sea) for a biogeographic study on Oithona similis. These specimens could not be assigned to O. similis or any of the other Oithona species known from the North Sea genetically. These specimens were identified as Oithona davisae Ferrari and Orsi 1984, a Northwest Pacific species, known as an invasive species from the Black Sea and the northwestern Mediterranean Sea. Recent sampling provided evidence that O. davisae is still present in the northern Wadden Sea and may thus now be a permanent plankton species.

  8. What Causes the North Sea Level to Rise Faster over the Last Decade ?

    Science.gov (United States)

    Karpytchev, Mikhail; Letetrel, Camille

    2013-04-01

    We combined tide gauge records (PSMSL) and satellite altimetry data (TOPEX/POSEIDON-JASON 1-2) to reconstruct the mean level of the North Sea and the Norwegian Sea Shelf (NS-NSS) over 1950-2012. The reconstructed NS-NSS mean sea level fluctuations reveal a pronounced interannual variability and a strong sea level acceleration since the mid-1990's. In order to understand the causes of this acceleration, the NS-NSS mean sea level was cross-correlated with the North Atlantic Oscillation and Arctic Oscillation indices. While the interannual variability of the mean sea level correlates well with the NAO/AO indices, the observed acceleration in the NS-NSS mean level is not linked linearly to the NAO/AO fluctuations. On the other hand, the Empirical Orthogonal Functions (EOF) analysis of steric sea level variations in the eastern North Atlantic gives a dominant EOF pattern (55% of variance explained) that varies on a decadal scale very closely to the NS-NSS mean level flcutuations. Also, the amplification in the temporal amplitude of the dominant steric sea level EOF corresponds to the acceleration observed in the NS-NSS mean sea level signal. This suggests that decadal variations in the mean level of the North Sea - the Norwegian Sea Shelf reflect changes in the Subpolar Front currents (Rossby, 1996).

  9. Field and numerical descriptions of fracture geometries and terminations in chalk containing chert layers and inclusions; implications for groundwater flow in Danish chalk aquifers

    Science.gov (United States)

    Seyum, S.

    2017-12-01

    This study is a description of the fracture distribution in laterally discontinuous chalk and chert layers, with an investigation on how fracture lengths and apertures vary as a function of applied stresses, material properties, and interface properties. Natural fractures intersect laterally extensive, discontinuous, chalk-chert material interfaces in 62 million-year old to 72 million-year old Chalk Group formations exposed at Stevns Klint, Denmark. Approximately one-third of Denmark's fresh water use is from chalk and limestone regional aquifers of the Chalk Group formations, where rock permeability is dominantly a function of open fracture connectivities. Fractured, centimeter- to decimeter-thick chert layers and inclusions (101 GPa elastic stiffness) are interlayered with fractured, meter-thick chalk layers (100 GPa elastic stiffness). Fractures are observed to terminate against and cross chalk-chert interfaces, affecting the vertical flow of water and pollutants between aquifers. The discontinuous and variably thin nature of chert layers at Stevns Klint effectively merges adjacent fracture-confining layers of chalk along discrete position intervals, resulting in lateral variability of fracture spacing. Finite element numerical models are designed to describe fracture interactions with stiff, chert inclusions of various shapes, thicknesses, widths, orientations, and interface friction and fracture toughness values. The models are two-dimensional with isotropic, continuous material in plane strain and uniformly applied remote principal stresses. These characteristics are chosen based on interpretations of the petrophysics of chalk and chert, the burial history of the rock, and the scale of investigation near fracture tips relative to grain sizes. The result are value ranges for relative stiffness contrasts, applied stresses, and material interface conditions that would cause fractures to cross, terminate at, or form along chalk-chert interfaces, with emphasis on

  10. Adsorption of hydrocarbons in chalk reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, L.

    1996-12-31

    The present work is a study on the wettability of hydrocarbon bearing chalk reservoirs. Wettability is a major factor that influences flow, location and distribution of oil and water in the reservoir. The wettability of the hydrocarbon reservoirs depends on how and to what extent the organic compounds are adsorbed onto the surfaces of calcite, quartz and clay. Organic compounds such as carboxylic acids are found in formation waters from various hydrocarbon reservoirs and in crude oils. In the present investigation the wetting behaviour of chalk is studied by the adsorption of the carboxylic acids onto synthetic calcite, kaolinite, quartz, {alpha}-alumina, and chalk dispersed in an aqueous phase and an organic phase. In the aqueous phase the results clearly demonstrate the differences between the adsorption behaviour of benzoic acid and hexanoic acid onto the surfaces of oxide minerals and carbonates. With NaCl concentration of 0.1 M and with pH {approx_equal} 6 the maximum adsorption of benzoic acid decreases in the order: quartz, {alpha}-alumina, kaolinite. For synthetic calcite and chalk no detectable adsorption was obtaind. In the organic phase the order is reversed. The maximum adsorption of benzoic acid onto the different surfaces decreases in the order: synthetic calcite, chalk, kaolinite and quartz. Also a marked difference in adsorption behaviour between probes with different functional groups onto synthetic calcite from organic phase is observed. The maximum adsorption decreases in the order: benzoic acid, benzyl alcohol and benzylamine. (au) 54 refs.

  11. North Sea focus on radwaste disposal

    International Nuclear Information System (INIS)

    Cope, D.

    1990-01-01

    At the recent North Sea Conference in the Netherlands possible future strategies for managing radioactive waste (radwaste) proved to be a contentious issue. Several of its North Sea littoral neighbours sought a categorical assurance that the UK would forego the option of constructing a subterranean radwaste repository which though accessed from land, extends under the coastline, or a sub-seabed facility reached from an offshore structure. It was pointed out that the UK has no present plans for such a radwaste repository. However, sub-seabed designs as a possibility for future repositories were not ruled out. NIREX has decided to concentrate its exploration work at two sites -Sellafield and Dounreay. Both sites are coastal locations and the government is aware that detailed geological exploration may favour extension of a radwaste repository beyond the shoreline, even if initially developed entirely on land. The design of such a radioactive waste repository is outlined. The position of NIREX and the Radioactive Waste Management Advisory Committee is discussed. (author)

  12. A tax reprieve for the North Sea?

    International Nuclear Information System (INIS)

    Kemp, A.

    1998-01-01

    The United Kingdom government has for the time being put to one side its intended review of the fiscal regime in the North Sea. Consistently low oil prices over the last year and the consequent effect on production have given rise to this decision. The ongoing debate on oil taxation in the UK over the past 18 months since the advent of a new government is examined. It has its roots in the last major changes to the oil tax regime which were made in 1993. It has been made clear by the government that the taxation review has not been abandoned and could come to the fore again should there be a substantial increase in oil and gas prices or if companies sought premature decommissioning of North Sea fields. (UK)

  13. Regionalization of climate model results for the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Kauker, F.

    1999-07-01

    A dynamical downscaling is presented that allows an estimation of potential effects of climate change on the North Sea. Therefore, the ocean general circulation model OPYC is adapted for application on a shelf by adding a lateral boundary formulation and a tide model. In this set-up the model is forced, first, with data from the ECMWF reanalysis for model validation and the study of the natural variability, and, second, with data from climate change experiments to estimate the effects of climate change on the North Sea. (orig.)

  14. Micro contaminants in surface sediments and macrobenthic invertebrates of the North Sea

    NARCIS (Netherlands)

    Everaarts, J.M.; Fischer, C.V.

    1989-01-01

    Trace metal concentrations (copper, zinc, cadmium and lead) were measured in the silt fraction (grainsize < 63 µm) of surface sediment of the North Sea. The concentrations varied in different areas of the Dutch continental shelf of the North Sea. The trace metal concentrations were highly related

  15. An Ichthyophonus hoferi epizootic in herring in the North Sea, the Skagerrak, the Kattegat and the Baltic Sea

    OpenAIRE

    Mellergaard, Stig; Spanggaard, Bettina

    1997-01-01

    An epizootic caused by the internal parasite Ichthyophonus hoferi in herring Clupea harengus was recorded from 1991 to 1993 in the waters around Denmark. A surveillance programme from research vessels and commercial fishing boats was conducted in the North Sea, Skagerrak, Kattegat and Baltic Sea. A total of 15769 hearts of adult herring were examined macroscopically for evidence of infection. The prevalence of the infection in this period decreased from 10.6 to 2.0% in the North Sea, from 8.0...

  16. Morphological response to a North Sea bed depression induced by gas mining

    NARCIS (Netherlands)

    Fluit, C.C.J.M.; Hulscher, Suzanne J.M.H.

    2002-01-01

    Gas mining leads to saucer-like surface depressions. In the North Sea, gas is currently mined at several offshore locations. The associated bed depression has a similar spatial extent as offshore tidal sandbanks, which are large-scale bed patterns covering a significant part of the North Sea bottom.

  17. Distribution and activity of petroleum hydrocarbon degrading bacteria in the North Sea and Baltic Sea

    International Nuclear Information System (INIS)

    Bruns, K.; Dahlmann, G.; Gunkel, W.

    1993-01-01

    Data were collected in 1988 and 1989 on the distribution and activity of petroleum hydrocarbon degrading bacteria in the North Sea and Baltic Sea. Crude oil degrading bacteria and the number of bacteria which in particular degrade naphthalene were quantified using a modified dilution method (MPN). Crude oil degrading bacteria were present in all of about 100 water samples, with as many as 10 3 ml -1 in some samples. Numbers of naphthalene degrading bacteria were at least tenfold lower. There is obviously a greater connection between this bacteria group and petroleum hydrocarbon (PHC) contamination than between the more nonspecific group of crude oil degrading bacteria and PHC contamination. Data from the North Sea show an extremely high abundance of hydrocarbon degrading bacteria, even in winter, while in the southern Baltic Sea low numbers of bacteria were found and slower crude oil degradation was observed. (orig.)

  18. UK wants more revenue from North Sea oil

    Energy Technology Data Exchange (ETDEWEB)

    1973-03-09

    The first report from the Committee of Public Accounts of the UK Parliament on North Sea gas and oil has revealed a situation under which the UK Exchequer apparently does not receive cash intake comparable to the Exchequers of other oil producing countries. So important are these findings that some of them are presented so that the industry at large, and particularly those engaged in North Sea exploration and production, will be aware of the UK situation. Recomendations are made that the government should take action substantially to improve the effective tax yield from operations on the continental shelf, and should consider among other methods the possibility of imposing a system of quantity taxation.

  19. Origin of channel systems in the Upper Cretaceous chalk group of the Paris Basin

    DEFF Research Database (Denmark)

    Esmerode, E. V.; Surlyk, Finn

    2009-01-01

    the presence of at least two distinct intra-chalk discordant reflections: a Top Santonian and a Mid-Campanian reflection. These reflections are in places associated with up to 120-m-deep channel-like structures trending preferentially N-S and NW-SE. The Mid-Campanian reflection is also sporadically associated...... with a massive secondary dolomite layer, the thicknesses of which may reach 110 m. Diagenesis does not seem to account for the formation of the discordant reflections, as there is neither a one-to-one relationship between the dolomite and discordant reflections, nor are there signs of systematic collapse...... is suggested due to the uninterrupted deep-marine chalk facies below and above both unconformities, and the unrealistically large sea-level drop of more than 200 m, which would be necessary for subaerial exposure of the central Paris Basin during the Campanian. The channels are oriented parallel to the margins...

  20. Spatial patterns of infauna, epifauna and demersal fish communities in the North Sea.

    NARCIS (Netherlands)

    Reiss, H.; Degraer, S.; Duineveld, G.C.A.; Craeymeersch, J.A.M.

    2010-01-01

    Understanding the structure and interrelationships of North Sea benthic invertebrate and fish communities and their underlying environmental drivers is an important prerequisite for conservation and spatial ecosystem management on scales relevant to ecological processes. Datasets of North Sea

  1. The continuing investment attraction af the North Sea to a large oil company

    International Nuclear Information System (INIS)

    Bijur, P.

    1992-01-01

    The North Sea is a success story of a partnership between government and industry in which everyone is winning. This paper considers what it will take to keep the success story going - to keep the North Sea attractive to large investors. First, the most significant of the future challenges facing investors here are outlined -competing investments, declining prospectivity and technical barriers. Some positive recommendations follow that may enable the oil industry to overcome the challenges and keep the North Sea a centre for petroleum investment into the next century. (author)

  2. To What Degree Thermal Cycles Affect Chalk Strength

    DEFF Research Database (Denmark)

    Livada, Tijana; Nermoen, Anders; Korsnes, Reidar Inger

    triaxial cell experiments. For dry rock, no significant effects of temperature cycling was found on average tensile strength, however the range of the tensile failure stress is doubled for the samples exposed to 50 temperature cycles, as opposed to those to none. For water saturated cores, the temperature......Chalk reservoirs could potentially undergo destabilization as the result of repeated cold water injection into a hot reservoir during water flooding. Preliminary results of an ongoing study are presented in this paper, which compare the impact of temperature cycling on mechanical behavior on dry...... and water saturated chalk. Sixty disks of dry Kansas chalk exposed to different number of temperature cycles were tested for tensile strength using a Brazilian test. Changes in elastic properties as function of number of temperature cycles of the same chalk, but now saturated in water, were studied using...

  3. Storing CO2 under the North Sea Basin - A key solution for combating climate change

    International Nuclear Information System (INIS)

    Skogen, T; Morris, B; Agerup, M; Svenningsen, S Oe; Kropelien, K F; Solheim, M; Northmore, B; Dixon, T; O'Carroll, K; Greaves, A; Golder, J; Selmer-Olsen, S; Sjoeveit, A; Kaarstad, O; Riley, N; Wright, I; Mansfield, C

    2007-06-01

    This report represents the first deliverable of the North Sea Basin Task Force, which Norway and the UK established in November 2005 to work together on issues surrounding the transport and storage of CO 2 beneath the North Sea. The North Sea represents the best geological opportunity for storing our CO 2 emissions away from the atmosphere for both the UK and Norway

  4. North Sea oil and the environment

    International Nuclear Information System (INIS)

    Cairns, W.J.

    1992-01-01

    This book, which is arranged in five sections, provides an historical record of the development of North Sea oil and gas over the past twenty years and records the lessons learnt from this experience. This first section provides an introductory framework to the three main themes, namely resources, environment and development. Section 2 is primarily concerned with the economic and social consequences of oil related development at two levels; firstly on the national economy and secondly the impact on local communities. Section 3 deals with impacts upon the physical environment and introduces the statutory land use planning system in Scotland. The Scottish approach to environmental assessment is reviewed and the need for mitigation by design explored. Section 4 examines specific field developments, and reviews the statutory controls and international initiatives regulating the extent of environmental disturbance and pollution from offshore operations. The effects of oil spillage and submarine pipelines on the environment and their impact on the fishing industry is followed by a discussion on the decommissioning and abandonment of offshore installations. Section 5 deals with the role and value of hazard and risk analysis in the siting, layout and safety zoning of onshore facilities and develops a case study on a major fractionation facility. The means of mitigating acute and chronic environmental risks are considered. A postscript provides a range of past comments and criticisms and finally draws some conclusions on the performance of environmental management and North Sea oil development. The North Sea oil and gas development experience proves that with wisdom, forethought and goodwill, industrial exploiters of natural resources can operate economically within legislative, policy, scientific, technical and design parameters without causing long-term irreversible environmental damage. (author)

  5. Quarter-Century Offshore Winds from SSM/I and WRF in the North Sea and South China Sea

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Astrup, Poul; Zhu, Rong

    2016-01-01

    We study the wind climate and its long-term variability in the North Sea and South China Sea, areas relevant for offshore wind energy development, using satellite-based wind data, because very few reliable long-term in-situ sea surface wind observations are available. The Special Sensor Microwave...

  6. Exploration and development of offshore oil and gas fields. [North Sea

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    In the last 9 years, the British companies, based on their rich engineering and commercial experience, have directed a considerable part of their material and manpower resources at developing oil and gas fields in the North Sea. The technological innovations used by British industry are: aero- and marine surveys to prospect for oil, underwater laying of pipelines, arrangement of platforms, etc.; exploratory drilling in the open sea and on dry land; design of platforms with regard for the depth of the water and unique weather conditions of the North Sea, their assembly and development; use of auxiliary ships and helicopters, and diving equipment.

  7. Interannual variability of north Atlantic Sea surface temperatures

    International Nuclear Information System (INIS)

    Bhatt, U.S.; Battisiti, D.S.; Alexander, M.A.

    1994-01-01

    In the midlatitude north Atlantic Ocean the pattern of sea surface temperature anomalies (ssta) is characterized by a north-south dipole. Bjerknes was the first to propose that the banded structure was associated with the interannual variability. Recently, these patterns have been studied more extensively. In this study the quantitative aspects of these patterns are examined through the use of a mixed-layer model (MLM)

  8. Airborne gravity survey of Lincoln Sea and Wandel Sea, north Greenland

    DEFF Research Database (Denmark)

    Olesen, Arne Vestergaard; Forsberg, René; Keller, K.

    2000-01-01

    In June 1998 National Survey and Cadastre Denmark (KMS) carried out an airborne gravity survey over the Polar Sea to the north of Greenland. A Twin Otter from Greenlandair, equipped with autopilot and additional fuel tanks, was employed for the survey. A modified marine LaCoste & Romberg gravimet...

  9. Phase equilibrium of North Sea oils with polar chemicals: Experiments and CPA modeling

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; Kontogeorgis, Georgios M.; von Solms, Nicolas

    2016-01-01

    This work consists of a combined experimental and modeling study for oil - MEG - water systems, of relevance to petroleum applications. We present new experimental liquid-liquid equilibrium data for the mutual solubility of two North Sea oils + MEG and North Sea oils + MEG + water systems...

  10. Seismic architecture of the Chalk Group from onshore reflection data in eastern Denmark

    DEFF Research Database (Denmark)

    Moreau, Julien; Anderskouv, Kresten; Boldreel, Lars Ole

    with the seismic stratigraphy. Several seismic facies are identified in the Chalk Group: the 'transparent' (white chalk), the stratified (marl-chalk alternations), the crudely stratified (flint-rich chalk) and the hummocky (bryozoan mounds). The units notably vary in thickness at a relatively small scale...... of the deformations appear to be restricted to the white chalk, whereas the stratified seismic facies are comparatively less disturbed. The origin of the structures observed in the white chalk can either be associated with the regional stress field or with differential diagenetic evolution between strata inducing...

  11. Dispersion of radionuclides in the European north-western seas: observations and modelling

    International Nuclear Information System (INIS)

    Bailly du Bois, Pascal

    2013-01-01

    In this report for an Accreditation to supervise research (HDR), the author reports the use over 30 years by the Cherbourg-Octeville IRSN Laboratory of artificial radionuclides in solution in sea water as oceanographic markers. Such measurements on radio-markers which are soluble in sea water, enabled a better knowledge of dissolved substance displacements in north-western seas of Europe, notably the Channel, the North Sea, the Celtic Sea, and the Irish Sea. The author reports researches which aimed at studying the dispersion of radionuclides in seawater and their use as water mass markers, at validating hydrodynamic models of dispersion at different time-space scales, at the understanding and simulation of the sedimentary transport, and at studying the transfer to living species. These different topics give the document its structure [fr

  12. Surfactant control of air-sea gas exchange from North Sea coastal waters and the Atlantic Meridional Transect

    Science.gov (United States)

    Pereira, R.

    2016-02-01

    Suppression of gas transfer velocity (kw) by surfactants are well established, both in laboratory wind flumes and purposeful oceanic releases. However, the effects on kw of time and space varying concentrations of natural surfactant are inadequately studied. We have developed an automated gas exchange tank for simultaneous high precision measurement of kw in unmodified seawater samples. Here we present data from two studies along a coastal North Sea transect during 2012-2013 and the Atlantic Meridional Transect (AMT) 24 from September to November 2014. Measurements of surfactant activity (SA), CDOM absorbance and chlorophyll-a have enabled us to characterize the effects of variable amounts of natural surfactant on kw. North Sea coastal waters range in k660 (kw normalized to the value for CO2 in freshwater at 20oC) was 6.8-24.5 cm hr-1 (n=20), with the ranges of SA, total CDOM absorbance (200-450 nm) and chlorophyll-a measured in the surface microlayer (SML) of our seawater samples were 0.08-0.38 mg l-1 T-X-100, 0.13-4.7 and 0.09-1.54 µg l-1, respectively. The AMT k660 ranged from 7.0-23.9 cm hr-1 (n=22), with SA measured in the SML and subsurface water (SSW) of our seawater samples ranging from 0.15-1.08 mg l-1 T-X-100 and 0.07-0.43 mg l-1 T-X-100, respectively. Importantly, we found 12-45% (North Sea) and 1-43% (AMT) k660 suppression relative to Milli-Q water that relate to seasonal and spatial differences in SA. The North Sea demonstrated notable seasonal influences on k660 suppression that were related to CDOM absorbance and chlorophyll-a. The degree of k660 suppression was highest in summer consistent with k660 control by natural surfactant. The degree of k660 suppression decreased with distance offshore in the North Sea and displayed a strong relationship with SA (r2 = 0.51-0.64, p = 0.02, n = 20). The AMT demonstrated notable differences in k660 suppression between hemispheres and across the Longhurst Provinces but the overall relationship between k660

  13. Bacterial and archaeal communities in sediments of the north Chinese marginal seas.

    Science.gov (United States)

    Liu, Jiwen; Liu, Xiaoshou; Wang, Min; Qiao, Yanlu; Zheng, Yanfen; Zhang, Xiao-Hua

    2015-07-01

    Microbial communities of the Chinese marginal seas have rarely been reported. Here, bacterial and archaeal community structures and abundance in the surface sediment of four sea areas including the Bohai Sea (BS), North Yellow Sea (NYS), South Yellow Sea (SYS), and the north East China Sea (NECS) were surveyed by 16S ribosomal RNA (rRNA) gene pyrosequencing and quantitative PCR. The results showed that microbial communities of the four geographic areas were distinct from each other at the operational taxonomic unit (OTU) level, whereas the microbial communities of the BS, NYS, and SYS were more similar to each other than to the NECS at higher taxonomic levels. Across all samples, Bacteria were numerically dominant relative to Archaea, and among them, Gammaproteobacteria and Euryarchaeota were predominant in the BS, NYS, and SYS, while Deltaproteobacteria and Thaumarchaeota were prevalent in the NECS. The most abundant bacterial genera were putative sulfur oxidizer and sulfate reducer, suggesting that sulfur cycle processes might prevail in these areas, and the high abundance of dsrB (10(7)-10(8) copies g(-1)) in all sites verified the dominance of sulfate reducer in the north Chinese marginal seas. The differences in sediment sources among the sampling areas were potential explanations for the observed microbial community variations. Furthermore, temperature and dissolved oxygen of bottom water were significant environmental factors in determining both bacterial and archaeal communities, whereas chlorophyll a in sediment was significant only in structuring archaeal community. This study presented an outline of benthic microbial communities and provided insights into understanding the biogeochemical cycles in sediments of the north Chinese marginal seas.

  14. Diversity and community structure of epibenthic invertebrates and fish in the North Sea

    DEFF Research Database (Denmark)

    Callaway, R.; Alsväg, J.; de Boois, I.

    2002-01-01

    The structure of North Sea benthic invertebrate and fish communities is an important indicator of anthropogenic and environmental impacts. Although North Sea fish stocks are monitored regularly, benthic fauna are not. Here, we report the results of a survey carried out in 2000, in which five...

  15. The Pleistocene reindeer of the North Sea - initial palaeontological data and archaeological remarks

    NARCIS (Netherlands)

    Glimmerveen, J; Mol, D; van der Plicht, H

    The interdisciplinary North Sea Project aims at investigating the biotic history of the Pleistocene in the Southern Bight of the North Sea. Humans were part of these biotopes too as Palaeolithic flint artefacts prove. Based on a large fossil record and radiocarbon dating, it becomes clear that

  16. Palaeoenvironmental changes across the Danian–Selandian boundary in the North Sea Basin

    DEFF Research Database (Denmark)

    Clemmensen, Anne; Thomsen, Erik

    2005-01-01

    cores from Storebælt in the eastern part of the North Sea Basin, we have reconstructed the palaeoenvironmental changes across the boundary. The benthic foraminiferal faunas belong to the “Midway-type fauna”. They are extremely rich and more than 260 taxa have been recognized. Q-mode cluster analysis......, the sea bottom conditions became colder and more acidic. This resulted in partial dissolution of the carbonates and the deposition shifted from marl to clay. Comparison with records from the Western Pyrenees, the Nile Basin and the eastern North America suggests that sea-level changes across the Danian......The Danian–Selandian boundary (not, vert, similar60 Ma) marks the cessation of 40 million years of carbonate deposition in the North Sea Basin and a shift to siliciclastic deposition. On the basis of variations in lithology, benthic and planktonic foraminifera and calcareous nannofossils in three...

  17. Ecology of the North Sea: Problems, successes, failures, future needs

    Science.gov (United States)

    Kinne, O.

    1995-03-01

    After defining ‘ecology’, outlining the basic categories of ecological research and listing examples of modern ecological investigations, this introductory paper focusses on basic considerations; it is, in essence, a programmatic contribution. Research details on the ecology of the North Sea are the subject of the following papers. The problems of ecological North Sea research are formidable. Hydrological and biological fluctuations and variabilities are pronounced. Exchange patterns with the Atlantic are complex, and the inputs of rivers and rain defy exact measurement and prediction. Season, weather, climate—and as yet insufficiently known and controlled human-caused impacts—further complicate the situation. All this results in an unusually high degree of uncertainty. New questions and problems arise before the old ones can be answered or solved. Nevertheless, ecological North Sea research has achieved many successes. The North Sea is the most intensively investigated sea area on our planet. Generations of zoologists, botanists and hydrographers — and more recently microbiologists, meteorologists, climatologists, chemists, pathologists and toxicologists — have produced an impressive body of knowledge. Slowly we are beginning to understand the forces that govern energy budgets and balances, material fluxes, and the factors that control and direct ecosystem dynamics. Essential driving forces of ecosystem dynamics result from microbial, especially bacterial, activities. Ecological modelling has paved the way for new theories and insights, and holds promise for progress towards a predictive ecology. Failures and shortcomings include insufficient long-term research, inadequately designed experiments, and misconceptions in environmental protection. Net changes in ecological processes of an heterogeneous and intensely varying environment such as the North Sea can only be comprehended adequately against the background of sustained measurements over decades

  18. Air-sea exchange fluxes of synthetic polycyclic musks in the North Sea and the Arctic.

    Science.gov (United States)

    Xie, Zhiyong; Ebinghaus, Ralf; Temme, Christian; Heemken, Olaf; Ruck, Wolfgang

    2007-08-15

    Synthetic polycyclic musk fragrances Galaxolide (HHCB) and Tonalide (AHTN) were measured simultaneously in air and seawater in the Arctic and the North Sea and in the rural air of northern Germany. Median concentrations of gas-phase HHCB and AHTN were 4 and 18 pg m(-3) in the Arctic, 28 and 18 pg m(-3) in the North Sea, and 71 and 21 pg m(-3) in northern Germany, respectively. Various ratios of HHCB/AHTN implied that HHCB is quickly removed by atmospheric degradation, while AHTN is relatively persistent in the atmosphere. Dissolved concentrations ranged from 12 to 2030 pg L(-1) for HHCB and from below the method detection limit (3 pg L(-1)) to 965 pg L(-1) for AHTN with median values of 59 and 23 pg L(-1), respectively. The medians of volatilization fluxes for HHCB and AHTN were 27.2 and 14.2 ng m(-2) day(-1) and the depositional fluxes were 5.9 and 3.3 ng m(-2) day(-1), respectively, indicating water-to-air volatilization is a significant process to eliminate HHCB and AHTN from the North Sea. In the Arctic, deposition fluxes dominated the air-sea gas exchange of HHCB and AHTN, suggesting atmospheric input controls the levels of HHCB and AHTN in the polar region.

  19. Virulence Profiles of Vibrio vulnificus in German Coastal Waters, a Comparison of North Sea and Baltic Sea Isolates

    Directory of Open Access Journals (Sweden)

    Nadja Bier

    2015-12-01

    Full Text Available Vibrio vulnificus is a halophilic bacterium of coastal environments known for sporadically causing severe foodborne or wound infections. Global warming is expected to lead to a rising occurrence of V. vulnificus and an increasing incidence of human infections in Northern Europe. So far, infections in Germany were exclusively documented for the Baltic Sea coast, while no cases from the North Sea region have been reported. Regional variations in the prevalence of infections may be influenced by differences in the pathogenicity of V. vulnificus populations in both areas. This study aimed to compare the distribution of virulence-associated traits and genotypes among 101 V. vulnificus isolates from the Baltic Sea and North Sea in order to assess their pathogenicity potential. Furthermore, genetic relationships were examined by multilocus sequence typing (MLST. A high diversity of MLST sequences (74 sequence types and differences regarding the presence of six potential pathogenicity markers were observed in the V. vulnificus populations of both areas. Strains with genotypes and markers associated with pathogenicity are not restricted to a particular geographic region. This indicates that lack of reported cases in the North Sea region is not caused by the absence of potentially pathogenic strains.

  20. Shallow gas in Cenozoic sediments of the Southern North Sea

    Science.gov (United States)

    Trampe, Anna F.; Lutz, Rüdiger; Franke, Dieter; Thöle, Hauke; Arfai, Jashar

    2013-04-01

    Shallow petroleum systems in the southern North Sea are known for several decades but they were not actively explored for a long time. In recent years these unconventional shallow petroleum systems are studied in greater detail and one shallow gas field (A-12) is in production in the Netherlands. Additionally, oil was encountered in Miocene sandstones in the southern Danish North Sea (Lille John well) just north of the Danish-German border. Seismic amplitude anomalies are an indication for hydrocarbons in sediments. Therefore we have mapped the occurrence of seismic amplitude anomalies in the German North Sea based on more than 25.000 km of 2D seismic data and around 4.000 km2 of 3D seismic data. Amplitude anomalies are ubiquitous phenomena in the study area. These anomalies are not only caused by hydrocarbons but also by changing lithologies e.g. peat or fluid migration. Therefore several classes of seismic anomalies, e.g. bright spots, chimneys, blanking areas and velocity pull-down were mapped. Examples for these classes were studied with AVO (amplitude variation with offset) analyses to verify the existence or non-existence of gas in the sediments. Shallow gas can be produced and transported through the dense pipeline grid of the southern and central North Sea or it could be burned offshore close to wind parks in small power plants and the electric energy then transported through the existing power connections of the wind parks. Thus enabling a continuous energy supply during calm wind periods. This study is carried out within the framework of the project "Geoscientific Potential of the German North Sea (GPDN)" in which the Cenozoic sedimentary system was mapped in great detail. A detailed model of delta evolution (Baltic river system) was developed which serves as a structural framework. The studied interval is time equivalent to the Utsira formation which is used offshore Norway for sequestration of CO2. These different possibilities of using or exploiting

  1. The fusion blanket program at Chalk River

    International Nuclear Information System (INIS)

    Hastings, I.J.

    1986-03-01

    Work on the Fusion Blanket Program commenced at Chalk River in 1984 June. Co-funded by Canadian Fusion Fuels Technology Project and Atomic Energy of Canada Limited, the Program utilizes Chalk River expertise in instrumented irradiation testing, ceramics, tritium technology, materials testing and compound chemistry. This paper gives highlights of studies to date on lithium-based ceramics, leading contenders for the fusion blanket

  2. Draft Memorandum for the North Sea

    International Nuclear Information System (INIS)

    2008-12-01

    In the National Water Plan it is described which measures must be taken to keep the Netherlands safe and livable for future generations and to make use of the chances offered by water. This memorandum serves as a document by means of which political choices for the North Sea policy, as formulated in the National Water Plan, are made more transparent [nl

  3. Controls on upper Campanian-Maastrichtian chalk deposition in the eastern Danish Basin

    DEFF Research Database (Denmark)

    Boussaha, Myriam; Thibault, Nicolas Rudolph; Anderskouv, Kresten

    2017-01-01

    % of the sediment. Sedimentation took place in deep water, below the photic zone and storm-wave base, and is characterized by decimetre to metre-scale variations in facies and trace fossil assemblages indicating repeated shifts in depositional environment. Integration of facies with published data on sea...... of accumulation rates and sea temperatures and is interpreted to represent a very broad set of deep water environmental conditions with an ample supply of calcareous nannofossil debris and intense bioturbation. Longer term shifts in deposition are best expressed by distribution of clay, flint and bioturbated...... micro-wackestone, bioturbated wackestone and laminated mudstone chalk facies, whereas the trace fossil assemblages appear less useful. The data set indicates overall shallowing over time with two distinctive events of clay influx to the basin during the late Campanian-earliest Maastrichtian and late...

  4. EDXRS study of aerosol composition variations in air masses crossing the North Sea

    International Nuclear Information System (INIS)

    Injuk, J.; Malderen, H. van; Grieken, R. van; Swietlicki, E.; Knox, J.M.; Schofield, R.

    1993-01-01

    X-ray emission techniques for bulk and individual particle analysis (EDXRF, EPXMA, micro-PIXE) were combined and applied in atmospheric research on the North Sea area as part of a field-study on air-sea exchange processes of particulate matter. The atmospheric loading for a number of elements was determined by EDXRF, yielding bulk concentrations for Mg, Al, Si, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Br and Sr. From these EDXRF data, deposition rates were derived and, based on a classical multivariate statistical approach, different aerosol sources were identified. Complementary to this work, EPXMA combined with automated image analysis was applied to individual size-segregated aerosol particles to determine their inorganic composition, physical size and shape. Also, the first results of micro-PIXE analyses on individual North Sea aerosol particles, particularly their large-size fraction, are discussed and compared with the corresponding EPXMA results. In summary, such a joint approach with the use of different x-ray emission techniques contributed to the resolution of the mixed structure of the lower North Sea troposphere and to the determination of the atmospheric supply of material to the North Sea environment. (author)

  5. Climate change facilitated range expansion of the non-native angular crab Goneplax rhomboides into the North Sea

    NARCIS (Netherlands)

    Neumann, H.; Boois, de I.J.; Kroncke, I.; Reiss, H.

    2013-01-01

    The angular crab Goneplax rhomboides is native to the north-eastern Atlantic and Mediterranean Sea. It has rarely been reported from the North Sea, with no evidence of sustainable populations. Compiled survey data, however, revealed an increasing abundance of this species in the North Sea since

  6. Evaluation of harvest and information needs for North American sea ducks.

    Science.gov (United States)

    Koneff, Mark D; Zimmerman, Guthrie S; Dwyer, Chris P; Fleming, Kathleen K; Padding, Paul I; Devers, Patrick K; Johnson, Fred A; Runge, Michael C; Roberts, Anthony J

    2017-01-01

    Wildlife managers routinely seek to establish sustainable limits of sport harvest or other regulated forms of take while confronted with considerable uncertainty. A growing body of ecological research focuses on methods to describe and account for uncertainty in management decision-making and to prioritize research and monitoring investments to reduce the most influential uncertainties. We used simulation methods incorporating measures of demographic uncertainty to evaluate risk of overharvest and prioritize information needs for North American sea ducks (Tribe Mergini). Sea ducks are popular game birds in North America, yet they are poorly monitored and their population dynamics are poorly understood relative to other North American waterfowl. There have been few attempts to assess the sustainability of harvest of North American sea ducks, and no formal harvest strategy exists in the U.S. or Canada to guide management. The popularity of sea duck hunting, extended hunting opportunity for some populations (i.e., special seasons and/or bag limits), and population declines have led to concern about potential overharvest. We used Monte Carlo simulation to contrast estimates of allowable harvest and observed harvest and assess risk of overharvest for 7 populations of North American sea ducks: the American subspecies of common eider (Somateria mollissima dresseri), eastern and western populations of black scoter (Melanitta americana) and surf scoter (M. perspicillata), and continental populations of white-winged scoter (M. fusca) and long-tailed duck (Clangula hyemalis). We combined information from empirical studies and the opinions of experts through formal elicitation to create probability distributions reflecting uncertainty in the individual demographic parameters used in this assessment. Estimates of maximum growth (rmax), and therefore of allowable harvest, were highly uncertain for all populations. Long-tailed duck and American common eider appeared to be at high

  7. A decision support system for assessing offshore wind energy potential in the North Sea

    International Nuclear Information System (INIS)

    Schillings, Christoph; Wanderer, Thomas; Cameron, Lachlan; Tjalling van der Wal, Jan; Jacquemin, Jerome; Veum, Karina

    2012-01-01

    Offshore wind energy (OWE) in the North Sea has the potential to meet large share of Europe’s future electricity demand. To deploy offshore wind parks in a rational way, the overall OWE potential has to be realistically determined. This has to be done on an international, cross-border level and by taking into account the existing man-made and nature-related uses of the North Sea. As spatial conflicts will arise between existing uses and the new OWE uses, a Decision Support System (DSS) based on a Geographic Information System (GIS) was developed. Based on data of existing sea uses and calculation rules for spatial prioritisation analysis, the DSS helps in identifying areas that are (1) generally suitable for offshore wind power, (2) strictly excluded or (3) negotiable with respect to other existing sea uses. The combination of this conflict analysis together with cost assumptions for offshore wind farms and their expected electricity yield leads to identification of favourable areas for OWE deployment in the North Sea. This approach helps to reduce the conflict between offshore wind deployment and existing sea uses in the North Sea for future planning. The results can assist decision makers in developing transnational roadmaps for OWE. - Highlights: ► Decision Support System (DSS) to identify offshore wind energy (OWE) potential in the North Sea. ► Spatial analysis of existing sea use functions and offshore wind energy potential. ► Input parameters of DSS depend on the level of OWE spatial priority assumed by the user. ► DSS performs the required calculations and provides results in form of maps and statistics. ► DSS available after registration at (www.windspeed.eu).

  8. Low-frequency variability in North Sea and Baltic Sea identified through simulations with the 3-D coupled physical–biogeochemical model ECOSMO

    Directory of Open Access Journals (Sweden)

    U. Daewel

    2017-09-01

    Full Text Available Here we present results from a long-term model simulation of the 3-D coupled ecosystem model ECOSMO II for a North Sea and Baltic Sea set-up. The model allows both multi-decadal hindcast simulation of the marine system and specific process studies under controlled environmental conditions. Model results have been analysed with respect to long-term multi-decadal variability in both physical and biological parameters with the help of empirical orthogonal function (EOF analysis. The analysis of a 61-year (1948–2008 hindcast reveals a quasi-decadal variation in salinity, temperature and current fields in the North Sea in addition to singular events of major changes during restricted time frames. These changes in hydrodynamic variables were found to be associated with changes in ecosystem productivity that are temporally aligned with the timing of reported regime shifts in the areas. Our results clearly indicate that for analysing ecosystem productivity, spatially explicit methods are indispensable. Especially in the North Sea, a correlation analysis between atmospheric forcing and primary production (PP reveals significant correlations between PP and the North Atlantic Oscillation (NAO and wind forcing for the central part of the region, while the Atlantic Multi-decadal Oscillation (AMO and air temperature are correlated to long-term changes in PP in the southern North Sea frontal areas. Since correlations cannot serve to identify causal relationship, we performed scenario model runs perturbing the temporal variability in forcing condition to emphasize specifically the role of solar radiation, wind and eutrophication. The results revealed that, although all parameters are relevant for the magnitude of PP in the North Sea and Baltic Sea, the dominant impact on long-term variability and major shifts in ecosystem productivity was introduced by modulations of the wind fields.

  9. Imaging the Danish Chalk Group with high resolution, 3-component seismics

    Science.gov (United States)

    Kammann, J.; Rasmussen, S. L.; Nielsen, L.; Malehmir, A.; Stemmerik, L.

    2016-12-01

    The Chalk Group in the Danish Basin forms important reservoirs to hydrocarbons as well as water resources, and it has been subject to several seismic studies to determine e.g. structural elements, deposition and burial history. This study focuses on the high quality seismic response of a survey acquired with an accelerated 45 kg weight drop and 3-component MEMS-based sensors and additional wireless vertical-type sensors. The 500 m long profile was acquired during one day close to a chalk quarry and chalk cliffs of the Stevns peninsula in eastern Denmark where the well-known K-T (Cretaceous-Tertiary) boundary and different chalk lithologies are well-exposed. With this simple and fast procedure we were able to achieve deep P-wave penetration to the base of the Chalk Group at about 900 m depth. Additionally, the CMP-processed seismic image of the vertical component stands out by its high resolution. Sedimentary features are imaged in the near-surface Danian, as well as in the deeper Maastrichtian and Upper Campanian parts of the Chalk Group. Integration with borehole data suggests that changes in composition, in particular clay content, correlate with changes in reflectivity of the seismic data set. While the pure chalk in the Maastrichtian deposits shows rather low reflectivity, succession enriched in clay appear to be more reflective. The integration of the mentioned methods gives the opportunity to connect changes in facies to the elastic response of the Chalk Group in its natural environmental conditions.

  10. A decision support system for assessing offshore wind energy potential in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Wanderer, T.; Schillings, C. [German Aerospace Center (DLR), Systems Analysis and Technology Assessment, Stuttgart (Germany); Cameron, L.; Veum, K. [Energy research Center of the Netherlands ECN, Policy Studies Department, Amsterdam (Netherlands); Tjalling van der Wal, J. [IMARES, Wageningen UR, Den Helder (Netherlands); Jacquemin, J. [GL Garrad Hassan, Paris (France)

    2012-10-15

    Offshore wind energy (OWE) in the North Sea has the potential to meet large share of Europe's future electricity demand. To deploy offshore wind parks in a rational way, the overall OWE potential has to be realistically determined. This has to be done on an international, cross-border level and by taking into account the existing man-made and nature-related uses of the North Sea. As spatial conflicts will arise between existing uses and the new OWE uses, a Decision Support System (DSS) based on a Geographic Information System (GIS) was developed. Based on data of existing sea uses and calculation rules for spatial prioritisation analysis, the DSS helps in identifying areas that are (1) generally suitable for offshore wind power, (2) strictly excluded or (3) negotiable with respect to other existing sea uses. The combination of this conflict analysis together with cost assumptions for offshore wind farms and their expected electricity yield leads to identification of favourable areas for OWE deployment in the North Sea. This approach helps to reduce the conflict between offshore wind deployment and existing sea uses in the North Sea for future planning. The results can assist decision makers in developing transnational roadmaps for OWE.

  11. Transport and hydraulically-induced recycling of phosphorous in the North Sea-Baltic Sea transition zone

    DEFF Research Database (Denmark)

    Kepp, Rikke; Struve, Anke; Christiansen, Christian

    2006-01-01

    to barotropic and tidal currents the gross transport is 5 times larger. The net transport is directed towards the North Sea mainly in the top 32 m of the water column but towards the Baltic Sea it occurs in the lower 5 m of the water column. The resulting transport of phosphorus is strongly affected by vertical...

  12. Sea Surface Temperature Climate Data Record for the North Sea and Baltic Sea

    DEFF Research Database (Denmark)

    Høyer, Jacob L.; Karagali, Ioanna

    2016-01-01

    A 30-yr climate data record (CDR) of sea surface temperature (SST) has been produced with daily gap-free analysis fields for the North Sea and the Baltic Sea region from 1982 to 2012 by combining the Pathfinder AVHRR satellite data record with the Along-Track Scanning Radiometer (ATSR) Reprocessing...... for Climate (ARC) dataset and with in situ observations. A dynamical bias correction scheme adjusts the Pathfinder observations toward the ARC and in situ observations. Largest Pathfinder-ARC differences are found in the summer months, when the Pathfinder observations are up to 0.4 °C colder than the ARC...... observations on average. Validation against independent in situ observations shows a very stable performance of the data record, with a mean difference of -0.06 °C compared to moored buoys and a 0.46 °C standard deviation of the differences. The mean annual biases of the SST CDR are small for all years...

  13. Investigation and evaluation of airborne pollution in the framework of PARCOM (North Sea) and HELCOM (Baltic Sea) - subproject: Measurements of trace metals

    International Nuclear Information System (INIS)

    Schneider, B.

    1993-01-01

    On the basis of measurements of the deposition and concentrations of atmospheric trace metals the annual input of some selected elements (Pb, Zn, Cd, Ni, V) into the North Sea and the Baltic Sea was estimated. For the Baltic Sea, deposition measurements with a buoy system in the Kiel Bight and data from the EGAP(HELCOM)-monitoring network were used. Data from the measurement stations were extrapolated to related sub-basins according to the deposition fields obtained from model calculations (EMEP). For the North Sea, a mean atmospheric trace metal distribution was determined from numerous measurements at a coastal site and over the central North Sea and the annual input was calculated by multiplication with corresponding deposition velocities and scavenging ratios. A comparison of the deposition data based on measurements with those from model calculations show good agreement in the case of Pb in the Baltic Sea as well as in the North Sea. However, for Zn and Cd large discrepancies are observed. Additionally, deposition processes were studied. Scavenging ratios were determined and dry deposition velocities were estimated by the use of a new method for high time resolution measurements of atmospheric trace metal concentrations (impactor/TXRF). (orig.). 9 figs., 14 tabs [de

  14. What is the pollution status of North Sea sediments?

    International Nuclear Information System (INIS)

    Chapman, P.M.; Heip, C.; Cofino, W.

    1993-01-01

    A March 1990 international sea-going workshop in Bremerhaven, Germany provided the opportunity to conduct detailed sediment toxicity testing in concert with studies of fish histopathology, bioaccumulation, benthic community structure, and sediment chemical contamination in the North Sea. Two gradients of sediment chemical contamination were tested, one from an abandoned oil platform and the other from the mouth of the Elbe River northward to the Dogger Bank. Using a preponderance of evidence approach, it was determined that sediments nearest the Elbe are moderately polluted (pollution is defined as contamination, toxicity, and community alteration) and that sediments offshore and at the Dogger Bank are unpolluted. Sediments nearest the oil platform showed evidence for a low level of pollution, but there was no evidence of pollution 125 m from the platform. The results suggest the testable hypothesis that North Sea sediments away from point sources of pollution such as coastal areas and drilling platforms are presently not polluted. 46 refs., 2 figs., 6 tabs

  15. Storing CO{sub 2} under the North Sea Basin - A key solution for combating climate change

    Energy Technology Data Exchange (ETDEWEB)

    Skogen, T; Morris, B; Agerup, M; Svenningsen, S Oe; Kropelien, K F; Solheim, M; Northmore, B; Dixon, T; O' Carroll, K; Greaves, A; Golder, J; Selmer-Olsen, S; Sjoeveit, A; Kaarstad, O; Riley, N; Wright, I; Mansfield, C

    2007-06-15

    This report represents the first deliverable of the North Sea Basin Task Force, which Norway and the UK established in November 2005 to work together on issues surrounding the transport and storage of CO{sub 2} beneath the North Sea. The North Sea represents the best geological opportunity for storing our CO{sub 2} emissions away from the atmosphere for both the UK and Norway

  16. The introduction of radionuclides over the atmosphere into the North Sea

    International Nuclear Information System (INIS)

    Kautsky, H.

    1983-01-01

    Although it is barely possible to provide exact data concerning the aerosol entry and the quantities of precipitation in the region of the North Sea, an attempt will be made to estimate the annual entry of radionuclides in the North Sea. As data for the calculations, available estimations of the quantity of precipitation over the sea, the content of radionuclides in the air and in the rain over land and the activities conveyed thereby to the earth, as well as the emission quantities of radionuclides with the exhaust air from nuclear power plants, are applied. It is quite clear that Tritium represents by far the main part of the radionuclides which enter the sea via precipitation. The majority of the other artificial radio nuclides, on the other hand, are to be viewed as being quantitatively insignificant. (orig./HP) [de

  17. Temperature and salinity profile data collected by bottle on multiple cruises in the Baltic Sea, Baffin Bay, Davis Strait, the North Atlantic Ocean, and the North Sea from 02 January 1985 to 13 November 1989 (NODC Accession 0000056)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts from DANA and other platforms in Baffin Sea, Baltic Sea, Davis Strait, North Sea, and North...

  18. Recruitment in a changing environment: the 2000s North Sea herring recruitment failure

    DEFF Research Database (Denmark)

    Payne, Mark; Hatfield, E.M.C.; Dickey-Collas, M.

    2009-01-01

    Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been an unpreced......Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been...... an unprecedented 6 sequential years of poor juvenile production (recruitment). Analysis suggests that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced. Contemporary warming of the North Sea has caused significant changes in the plankton community...

  19. Sleep and Alertness in North Sea Helicopter Operations

    NARCIS (Netherlands)

    Simons, M.; Wilschut, E.S.; Valk, P.J.L.

    2011-01-01

    Introduction : Dutch North Sea helicopter operations are characterized by multiple sector flights to offshore platforms under difficult environmental conditions. In the context of a Ministry of Transport program to improve safety levels of helicopter operations, we assessed effects of pre-duty

  20. A southern North Sea Miocene dinoflagellate cyst zonation

    NARCIS (Netherlands)

    Munsterman, D.K.; Brinkhuis, H.

    2004-01-01

    An integrated stratigraphical analysis emphasizing organic-walled dinoflagellate cyst (dinocyst) distribution has been carried out on multiple boreholes penetrating the Miocene in the subsurface of the Netherlands (southern North Sea Basin). The bulk of the investigated successions is attributed to

  1. Chalk: composition, diagenesis and physical properties

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2007-01-01

    Chalk is a sedimentary rock of unusually high homogeneity on the scale where physical properties are measured, but the properties fall in wide ranges. Chalk may thus be seen as the ideal starting point for a physical understanding of rocks in general. Properties as porosity, permeability, capillary...... involving clay, silica, and calcite are interlinked, but progress differently in different localities. This partly depends on primary sediment composition, including organic content, which may induce the formation of concretions by microbial action. The diagenetic processes also depend on water depth, rate...

  2. Low field NMR surface relaxivity studies of chalk and argillaceous sandstones

    DEFF Research Database (Denmark)

    Katika, Konstantina; Fordsmand, Henrik; Fabricius, Ida Lykke

    2017-01-01

    the accuracy of predictions of petrophysical properties of various rocks with the use of NMR spectrometry. We perform laboratory transverse relaxation (T2) measurements on water saturated Gorm field chalk, Stevns Klint chalk, Solsort field greensand and Berea sandstone. These rocks are of particular interest...... field chalk and Solsort field greensand have higher ρ at higher Larmor frequency. By contrast, ρ of the purely calcitic Stevns chalk and quartzitic Berea sandstone proved not to be affected by the changes in frequency. T2 distributions at temperatures ranging from 10 °C to 60 °C provided comparison...

  3. Prey selection by North Sea herring (Clupea harengus) with special reference to fish eggs

    NARCIS (Netherlands)

    Segers, F.H.I.D.; Dickey-Collas, M.; Rijnsdorp, A.D.

    2007-01-01

    The herring stock in the North Sea in recent years has recovered to a relatively high biomass, and here we investigate prey selection of individual North Sea herring when population numbers are high. The diet composition, and specifically pelagic fish eggs, was investigated in February 2004. Samples

  4. Seamount physiography and biology in the north-east Atlantic and Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    T. Morato

    2013-05-01

    Full Text Available This work aims at characterising the seamount physiography and biology in the OSPAR Convention limits (north-east Atlantic Ocean and Mediterranean Sea. We first inferred potential abundance, location and morphological characteristics of seamounts, and secondly, summarized the existing biological, geological and oceanographic in situ research, identifying examples of well-studied seamounts. Our study showed that the seamount population in the OSPAR area (north-east Atlantic and in the Mediterranean Sea is large with around 557 and 101 seamount-like features, respectively. Similarly, seamounts occupy large areas of about 616 000 km2 in the OSPAR region and of about 89 500 km2 in the Mediterranean Sea. The presence of seamounts in the north-east Atlantic has been known since the late 19th century, but overall knowledge regarding seamount ecology and geology is still relatively poor. Only 37 seamounts in the OSPAR area (3.5% of all seamounts in the region, 22 in the Mediterranean Sea (9.2% of all seamounts in the region and 25 in the north-east Atlantic south of the OSPAR area have in situ information. Seamounts mapped in both areas are in general very heterogeneous, showing diverse geophysical characteristics. These differences will likely affect the biological diversity and production of resident and associated organisms.

  5. Deglacial and Holocene sea-ice variability north of Iceland and response to ocean circulation changes

    Science.gov (United States)

    Xiao, Xiaotong; Zhao, Meixun; Knudsen, Karen Luise; Sha, Longbin; Eiríksson, Jón; Gudmundsdóttir, Esther; Jiang, Hui; Guo, Zhigang

    2017-08-01

    Sea-ice conditions on the North Icelandic shelf constitute a key component for the study of the climatic gradients between the Arctic and the North Atlantic Oceans at the Polar Front between the cold East Icelandic Current delivering Polar surface water and the relatively warm Irminger Current derived from the North Atlantic Current. The variability of sea ice contributes to heat reduction (albedo) and gas exchange between the ocean and the atmosphere, and further affects the deep-water formation. However, lack of long-term and high-resolution sea-ice records in the region hinders the understanding of palaeoceanographic change mechanisms during the last glacial-interglacial cycle. Here, we present a sea-ice record back to 15 ka (cal. ka BP) based on the sea-ice biomarker IP25, phytoplankton biomarker brassicasterol and terrestrial biomarker long-chain n-alkanols in piston core MD99-2272 from the North Icelandic shelf. During the Bølling/Allerød (14.7-12.9 ka), the North Icelandic shelf was characterized by extensive spring sea-ice cover linked to reduced flow of warm Atlantic Water and dominant Polar water influence, as well as strong meltwater input in the area. This pattern showed an anti-phase relationship with the ice-free/less ice conditions in marginal areas of the eastern Nordic Seas, where the Atlantic Water inflow was strong, and contributed to an enhanced deep-water formation. Prolonged sea-ice cover with occasional occurrence of seasonal sea ice prevailed during the Younger Dryas (12.9-11.7 ka) interrupted by a brief interval of enhanced Irminger Current and deposition of the Vedde Ash, as opposed to abruptly increased sea-ice conditions in the eastern Nordic Seas. The seasonal sea ice decreased gradually from the Younger Dryas to the onset of the Holocene corresponding to increasing insolation. Ice-free conditions and sea surface warming were observed for the Early Holocene, followed by expansion of sea ice during the Mid-Holocene.

  6. Effect of Fluid Dynamic Viscosity on the Strength of Chalk

    DEFF Research Database (Denmark)

    Hedegaard, K.; Fabricius, Ida Lykke

    The mechanical strength of high porosity and weakly cemented chalk is affected by the fluid in the pores. In this study, the effect of the dynamic viscosity of non-polar fluids has been measured on outcrop chalk from Sigerslev Quarry, Stevns, Denmark. The outcome is that the measured strength...... of the chalk decreases with increasing dynamic viscosity. The proposed qualitative explanation is that pressure difference supports and enhances the generation of microscopic shear and tensile failures....

  7. Influence of effective stress coefficient on mechanical failure of chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Hjuler, M.L.

    2012-01-01

    The Effective stress coefficient is a measure of how chalk grains are connected with each other. The stiffness of chalk may decrease if the amount of contact cements between the grains decreases, which may lead to an increase of the effective stress coefficient. We performed CO2 injection in chal...... precise failure strength of chalk during changed stress state and under the influence of chemically reactive fluids during production of hydrocarbon and geological storage CO2....

  8. Two centuries of observed atmospheric variability and change over the North Sea region

    Science.gov (United States)

    Stendel, Martin; van den Besselaar, Else; Hannachi, Abdel; Kent, Elizabeth; Lefebvre, Christiana; Rosenhagen, Gudrun; Schenk, Frederik; van der Schrier, Gerard; Woollings, Tim

    2016-04-01

    In the upcoming North Sea Region Climate Change Assessment (NOSCCA), we present a synthesis of current knowledge about past, present and possible future climate change in the North Sea region. A climate change assessment from published scientific work has been conducted as a kind of regional IPCC report, and a book has been produced that will be published by Springer in 2016. In the framework of the NOSCCA project, we examine past and present studies of variability and changes in atmospheric variables within the North Sea region over the instrumental period, roughly the past 200 years, based on observations and reanalyses. The variables addressed in this presentation are large-scale circulation, pressure and wind, surface air temperature, precipitation and radiative properties (clouds, solar radiation, and sunshine duration). While air temperature over land, not unexpectedly, has increased everywhere in the North Sea region, with strongest trends in spring and in the north of the region, a precipitation increase has been observed in the north and a decrease in the south of the region. This pattern goes along with a north-eastward shift of storm tracks and is in agreement with climate model projections under enhanced greenhouse gas concentrations. For other variables, it is not obvious which part of the observed changes may be due to anthropogenic activities and which is internally forced. It remains also unclear to what extent atmospheric circulation over the North Sea region is influenced by distant factors, in particular Arctic sea-ice decline in recent decades. There are indications of an increase in the number of deep cyclones (but not in the total number of cyclones), while storminess since the late 19th century shows no robust trends. The persistence of circulation types appears to have increased over the last century, and consequently, there is an indication for 'more extreme' extreme events. However, changes in extreme weather events are difficult to assess

  9. Impact of North Atlantic Current changes on the Nordic Seas and the Arctic Ocean

    OpenAIRE

    Kauker, Frank; Gerdes, Rüdiger; Karcher, Michael; Köberle, Cornelia

    2005-01-01

    The impact of North Atlantic Current (NAC) volume, heat, and salt transport variability onto the NordicSeas and the Arctic Ocean is investigated using numerical hindcast and sensitivity experiments. Theocean-sea ice model reproduces observed propagation pathways and speeds of SST anomalies.Part of the signal reaching the entrance to the Nordic Seas between Iceland and Scotland originatesin the lower latitude North Atlantic. Response experiments with different prescribed conditionsat 50N show ...

  10. Regional seesaw between the North Atlantic and Nordic Seas during the last glacial abrupt climate events

    Directory of Open Access Journals (Sweden)

    M. Wary

    2017-06-01

    Full Text Available Dansgaard–Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle. Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48–30 ka interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional palaeorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that re-emerged in the Nordic Seas and provided moisture towards Greenland summit.

  11. Evidence for a Middle Pleistocene glaciation of MIS 8 age in the southern North Sea

    NARCIS (Netherlands)

    Beets, C.J.

    2005-01-01

    In the coresof borehole 89/2, situated at 541 00 010N and 51 00 040E about 70 km north of the Frisian Islands in the southern North Sea, two diamictonsle vels are found at 770 and 100m below sea floor (i.e. 7110 and 140 below present sea level), respectively. Both diamictonsap pear to be older than

  12. The North Sea contracting industry

    International Nuclear Information System (INIS)

    Wright, P.J.C.

    1996-09-01

    The North Sea Contracting Industry provides in-depth profiles of major contracting organisations including manpower, facilities, expertise, future directions and financial details. It addresses key issues such as: how will the role of operators and contractors change toward 2000 and beyond?; how will the contractor-operator relationship develop?; will the contractors take a more speculative role in projects such as leasing and contract to produce?; does the future belong to broad skilled providers or small specialised niche players, or both?; and how will rapid technological improvements affect the industry? (author)

  13. Importance of ocean circulation in ecological modeling: An example from the North Sea

    Science.gov (United States)

    Skogen, Morten D.; Moll, Andreas

    2005-09-01

    There is an increasing number of ecological models for the North Sea around. Skogen and Moll (2000) [Skogen, M.D., Moll, A. 2000. Interannual variability of the North Sea primary production: comparison from two model studies. Continental Shelf Research 20 (2), 129-151] compared the interannual variability of the North Sea primary production using two state-of-the-art ecological models, NORWECOM and ECOHAM1. Their conclusion was that the two models agreed on an annual mean primary production, its variability and the timing and size of the peak production. On the other hand, there was a low (even negative dependent of area) correlation in the production in different years between the two models. In the present work, these conclusions are brought further. To try to better understand the observed differences between the two models, the two ecological models are run in an identical physical setting. With such a set-up also the interannual variability between the two models is in agreement, and it is concluded that the single most important factor for a reliable modeling of phytoplankton and nutrient distributions and transports within the North Sea is a proper physical model.

  14. Phytoplankton of the North Sea and its dynamics: A review

    Science.gov (United States)

    Reid, P. C.; Lancelot, C.; Gieskes, W. W. C.; Hagmeier, E.; Weichart, G.

    Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m -2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of England, the Netherlands, Germany and Denmark. Data collected since 1932 during the Continuous Plankton Recorder Survey show consistent patterns of geographical, seasonal and annual variation in the distribution of phytoplankton and its major taxonomic components. There is a trend of increased colouration in Recorder silks in the southern North Sea until approximately 1975 since when Colour levels (assumed to be indicative of algal biomass) have declined. In the eutrophic Dutch Wadden Sea the algal crop continued to increase; in Dutch coastal North Sea waters a trend of biomass increase reversed since 1984, apparently due to a reduction in Rhine river outflow. Long-term observations made at Helgoland since the 60's also show trends of increasing nutrients and phytoplankton biomass only to 1984. Adverse effects such as deoxygenation, foam formation and toxin production have been linked to mass concentrations of algae known as blooms. There is no evidence from existing reports for an increase in their frequency, although some years stand out with larger numbers. Occurrence of blooms can partly be explained by hydrographic conditions. More than 30 taxa are recognised as occurring in bloom proportions in the North Sea, approximately one third of which can be toxic. The crop of Bacillariophyceae (diatoms) is not likely to increase with eutrophication due to silicate limitation. An extensive subsurface maximum of armoured dinoflagellates, its abundance gouverned by hydrographic conditions, is the most characteristic feature of the central and northern North Sea in the summer months. Abundance, sometimes dominance, of picoplankton and of species that are not readily detected by

  15. North Sea Scyphomedusae; summer distribution, estimated biomass and significance particularly for 0-group Gadoid fish

    Science.gov (United States)

    Hay, S. J.; Hislop, J. R. G.; Shanks, A. M.

    Data on the by-catch of Scyphomedusae from pelagic trawls was collected during the routine ICES International 0-group Gadoid Surveys of the North Sea, in June and July of the years 1971-1986 (except 1984). These data are used to describe the distributions, abundances and biomasses of three common North Sea Scyphomedusae: Aurelia aurita (L.), Cyanea capillata (L.) and C. lamarckii (Péron & Lesuer). Information is also presented on inter-annual variability, size (umbrella diameter) frequencies and, for the Cyanea species, umbrella diameter: wet weight relationships. The general role and ecological significance of Scyphomedusae is discussed and, given the well known 'shelter' relationships between Scyphomedusae and certain 0-group fish, whiting ( Merlangius merlangus) and haddock ( Melanogrammus aeglefinus), in particular. The data were examined for evidence of such relationships. Aurelia aurita, although fairly widespread in the northern North Sea was virtually absent from the central North Sea but very abundant in coastal waters. This species was particularly abundant off the Scottish east coast and especially in the Moray Firth. Cyanea lamerckii was most abundant in the southern and eastern North Sea. More widespread than Aurelia, this species was also most abundant in coastal regions, particularly off the Danish west coast. Cyanea capillata, with a more northern distribution was also more widely distributed and abundant offshore. This species was most abundant in the area between the Orkney/Shetland Isles and the Norwegian Deep and in shelf waters of the north west approaches to the North Sea. As with C. lamarckii it was also, in some years, abundant off the Scottish east coast and west of Denmark. The abundance and the size frequency of the jellyfish show considerable inter-annual variability, and variability between regions of the North Sea. It is considered that hydrographic variability and differences in food supply to both medusae and to their sessile

  16. Grey gurnard ( Eutrigla gurnadus ) in the North Sea: an emerging key predator?

    DEFF Research Database (Denmark)

    Floeter, J.; Kempf, A.; Vinther, Morten

    2005-01-01

    Grey gurnard (Eutrigla gurnadus) is a widely distributed demersal species in the North Sea that has been ranked frequently among the 10 dominant species. Since the late 1980s, grey gurnard catch rates in the international bottom trawl surveys showed a pronounced increase and it was included...... as an "other predator" in the North Sea multispecies virtual population analysis (MSVPA) in 1997. The MSVPA results estimated grey gurnard to be responsible for approximately 60% of the total predation mortality on age-0 Atlantic cod (Gadus morhua). Long-term MSVPA predictions led to the extinction of North...... Sea cod. As a possible technical reason, the Holling type II functional response implemented in the model was discussed. In the current analysis, it was demonstrated that the Holling type II functional response was not responsible for the extinction of cod in the model, which was rather a true effect...

  17. Phosphorus binding by poorly crystalline iron oxides in North Sea sediments

    NARCIS (Netherlands)

    Slomp, C.P.; Gaast, S. J. van der; Raaphorst, W. van

    1996-01-01

    Differential X-ray powder diffraction (DXRD) and extraction procedures were used to characterize the iron oxides present in four sediments from contrasting environments in the North Sea. Stations were located in depositional areas on the southern shelf (German Bight) and on the north-eastern

  18. Not normally manned compression platforms for the North Sea

    International Nuclear Information System (INIS)

    Kumaran, K.S.

    1994-01-01

    Gas turbine driven gas compressors have been widely used on manned offshore facilities. Similarly unmanned gas turbine driven compressor stations have been in operation onshore with major gas transmission companies in Europe, North America and elsewhere. This paper summarizes a recent joint industry study to investigate the technical and economic feasibility of Not Normally Manned (NNM) Offshore Compression Facilities in terms of reliability, availability and maintainability. Classification of not normally manned (or unmanned) offshore facilities in the UK North Sea is in accordance with HSE Operations Notice 8. ON8 specifies criteria for offshore visits, visit hours and number of personnel on board for the operation of NNM platforms. This paper describes a typical Southern North Sea gas platform being considered for NNM compressor application. The conclusions from the study was that NNM compression is technically feasible with the facilities being able to provide an availability in excess of 98%. Life cycle costs were of the order of 70% of manned facilities thus significantly improving field development economics

  19. Inter-annual variability of North Sea plaice spawning habitat

    Science.gov (United States)

    Loots, C.; Vaz, S.; Koubbi, P.; Planque, B.; Coppin, F.; Verin, Y.

    2010-11-01

    Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January-March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence-absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.

  20. Mechanisms controlling the intra-annual mesoscale variability of SST and SPM in the southern North Sea

    Science.gov (United States)

    Pietrzak, Julie D.; de Boer, Gerben J.; Eleveld, Marieke A.

    2011-04-01

    Thermal and optical remote sensing data were used to investigate the spatial and temporal distribution of sea surface temperature (SST) and of suspended particulate matter (SPM) in the southern North Sea. Monthly SST composites showed pronounced seasonal warming of the southern North Sea and delineated the English coastal and continental coastal waters. The East-Anglia Plume is the dominant feature of the English coastal waters in the winter and autumn SPM composites, and the Rhine region of freshwater influence (ROFI), including the Flemish Banks, is the dominant feature of the continental waters. These mesoscale spatial structures are also influenced by the evolution of fronts, such as the seasonal front separating well-mixed water in the southern Bight, from the seasonally stratified central North Sea waters. A harmonic analysis of the SST and SPM images showed pronounced seasonal variability, as well as spring-neap variations in the level of tidal mixing in the East Anglia Plume, the Rhine ROFI and central North Sea. The harmonic analysis indicates the important role played by the local meteorology and tides in governing the SST and near-surface SPM concentrations in the southern North Sea. In the summer, thermal stratification affects the visibility of SPM to satellite sensors in the waters to the north of the Flamborough and Frisian Fronts. Haline stratification plays an important role in the visibility of SPM in the Rhine ROFI throughout the year. When stratified, both regions typically exhibit low surface SPM values. A numerical model study, together with the harmonic analysis, highlights the importance of tides and waves in controlling the stratification in the southern North Sea and hence the visibility of SPM.

  1. An Ichthyophonus hoferi epizootic in herring in the North Sea, the Skagerrak, the Kattegat and the Baltic Sea

    DEFF Research Database (Denmark)

    Mellergaard, Stig; Spanggaard, Bettina

    1997-01-01

    An epizootic caused by the internal parasite Ichthyophonus hoferi in herring Clupea harengus was recorded from 1991 to 1993 in the waters around Denmark. A surveillance programme from research vessels and commercial fishing boats was conducted in the North Sea, Skagerrak, Kattegat and Baltic Sea...

  2. The North Atlantic Oscillation: variability and interactions with the North Atlantic ocean and Artic sea ice

    Energy Technology Data Exchange (ETDEWEB)

    Jung, T

    2000-07-01

    The North Atlantic oscillation (NAO) represents the dominant mode of atmospheric variability in the North Atlantic region and describes the strengthening and weakening of the midlatitude westerlies. In this study, variability of the NAO during wintertime and its relationship to the North Atlantic ocean and Arctic sea ice is investigated. For this purpose, observational data are analyzed along with integrations of models for the Atlantic ocean, Arctic sea ice, and the coupled global climate system. From a statistical point of view, the observed NAO index shows unusually high variance on interdecadal time scales during the 20th century. Variability on other time scales is consistent with realizations of random processes (''white noise''). Recurrence of wintertime NAO anomalies from winter-to-winter with missing signals during the inbetween nonwinter seasons is primarily associated with interdecadal variability of the NAO. This recurrence indicates that low-frequency changes of the NAO during the 20th century were in part externally forced. (orig.)

  3. The North Atlantic Oscillation: variability and interactions with the North Atlantic ocean and Artic sea ice

    Energy Technology Data Exchange (ETDEWEB)

    Jung, T.

    2000-07-01

    The North Atlantic oscillation (NAO) represents the dominant mode of atmospheric variability in the North Atlantic region and describes the strengthening and weakening of the midlatitude westerlies. In this study, variability of the NAO during wintertime and its relationship to the North Atlantic ocean and Arctic sea ice is investigated. For this purpose, observational data are analyzed along with integrations of models for the Atlantic ocean, Arctic sea ice, and the coupled global climate system. From a statistical point of view, the observed NAO index shows unusually high variance on interdecadal time scales during the 20th century. Variability on other time scales is consistent with realizations of random processes (''white noise''). Recurrence of wintertime NAO anomalies from winter-to-winter with missing signals during the inbetween nonwinter seasons is primarily associated with interdecadal variability of the NAO. This recurrence indicates that low-frequency changes of the NAO during the 20th century were in part externally forced. (orig.)

  4. Uranium traps in the phosphate bearing sudr chalk, in northeastern sinai, Egypt

    International Nuclear Information System (INIS)

    Hussein, H.A.; El-Aassy, I.E.; Mahdy, M.A.; Dabbour, G.A.; Mansour, M.Gh.; Morsy, A.M.

    1998-01-01

    The maastrichtian sudr formation in northeastern sinai is composed of three members, the lower chalk, the middle phosphate and chart-bearing and the upper chalk members. Lemon yellow secondary uranium mineralization, distributed in the lower chalk member and in some phosphate beds from the middle phosphate member are observed. The XRD analyses of some samples from the uranium bearing chalk and the phosphate beds showed the presence of the secondary uranium minerals carnotite, bergenite and upalite. The mode of uranium occurrences could be interpreted as a result of the phosphatic beds decomposition and their subjection to later diagenetic processes. Uranium leaching circulation from phosphate rocks led to the liberation of uranium from the phosphates, and vanadium from the bituminous material and clay minerals. These migrated and were deposited locally and within the underlying chalk beds which acted as a lithologic trap

  5. Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe

    Science.gov (United States)

    Ho-Hagemann, Ha Thi Minh; Gröger, Matthias; Rockel, Burkhardt; Zahn, Matthias; Geyer, Beate; Meier, H. E. Markus

    2017-12-01

    This study introduces a new approach to investigate the potential effects of air-sea coupling on simulated precipitation inland over Central Europe. We present an inter-comparison of two regional climate models (RCMs), namely, the COSMO-CLM (hereafter CCLM) and RCA4 models, which are configured for the EURO-CORDEX domain in the coupled and atmosphere-only modes. Two versions of the CCLM model, namely, 4.8 and 5.0, join the inter-comparison being almost two different models while providing pronouncedly different summer precipitation simulations because of many changes in the dynamics and physics of CCLM in version 5.0. The coupling effect on the prominent summer dry bias over Central Europe is analysed using seasonal (JJA) mean statistics for the 30-year period from 1979 to 2009, with a focus on extreme precipitation under specific weather regimes. The weather regimes are compared between the coupled and uncoupled simulations to better understand the mechanism of the coupling effects. The comparisons of the coupled systems with the atmosphere-only models show that coupling clearly reduces the dry bias over Central Europe for CCLM 4.8, which has a large dry summer bias, but not for CCLM 5.0 and RCA4, which have smaller dry biases. This result implies that if the atmosphere-only model already yields reasonable summer precipitation over Central Europe, not much room for improvement exists that can be caused by the air-sea coupling over the North Sea and the Baltic Sea. However, if the atmosphere-only model shows a pronounced summer dry bias because of a lack of moisture transport from the seas into the region, the considered coupling may create an improved simulation of summer precipitation over Central Europe, such as for CCLM 4.8. For the latter, the benefit of coupling varies over the considered timescales. The precipitation simulations that are generated by the coupled system COSTRICE 4.8 and the atmosphere-only CCLM 4.8 are mostly identical for the summer mean

  6. Buried paleo-sedimentary basins in the north-eastern Black Sea-Azov Sea area and tectonic implications (DOBRE-2)

    Science.gov (United States)

    Starostenko, Vitaly; Stephenson, Randell; Janik, Tomasz; Tolkunov, Anatoly

    2014-05-01

    A number of independent but inter-related projects carried out under the auspices of various national and international programmes in Ukraine including DARIUS were aimed at imaging the upper lithosphere, crustal and sedimentary basin architecture in the north-eastern Black Sea, southern Crimea and Kerch peninsulas and the Azov Sea. This region marks the transition from relatively undisturbed Precambrian European cratonic crust and lithosphere north of the Azov Sea to areas of significant Phanerozoic tectonics and basin development, in both extensional as well as compressional environments, to the south, including the eastern Black Sea rift, which is the main sedimentary basin of the study area. The wide-angle reflection and refraction (WARR) profile DOBRE-2, a Ukrainian national project with international participation (see below), overlapping some 115 km of the southern end of the DOBREfraction'99 profile (that crosses the intracratonic Donbas Foldbelt) in the north and running to the eastern Black Sea basin in the south, utilised on- and offshore recording and energy sources. It maps crustal velocity structure across the craton margin and documents, among other things, that the Moho deepens from 40 km to ~47 km to the southwest below the Azov Sea and Crimean-Caucasus deformed zone. A regional CDP seismic profile coincident with DOBRE-2, crossing the Azov Sea, Kerch Peninsula and the north-eastern Black Sea southwest to the Ukraine-Turkey border, acquired by Ukrgeofisika (the Ukrainian national geophysical company) reveals in its inferred structural relationships the ages of Cretaceous and younger extensional and subsequent basin inversion tectonic events as well as the 2D geometry of basement displacement associated with post mid-Eocene inversion. A direct comparison of the results of the WARR velocity model and the near-vertical reflection structural image has been made by converting the former into the time domain. The results dramatically demonstrate that

  7. Distribution and sources of dissolved black carbon in surface waters of the Chukchi Sea, Bering Sea, and the North Pacific Ocean

    Science.gov (United States)

    Nakane, Motohiro; Ajioka, Taku; Yamashita, Youhei

    2017-05-01

    Pyrogenic carbon, also called black carbon (BC), is an important component in the global carbon cycle. BC produced by biomass burning or fossil fuel combustion is transported to oceans by the atmosphere or rivers. However, environmental dynamics (i.e., major sources and sinks) of BC in marine environments have not been well documented. In this study, dissolved BC (DBC) collected from surface waters of the Chukchi Sea, the Bering Sea, and the subarctic and subtropical North Pacific were analyzed using the benzene polycarboxylic acid (BPCA) method. The DBC concentration and the ratio of B5CA and B6CA to all BPCAs (an index of the DBC condensation degree) ranged from 4.8 to 15.5 µg-C L-1 and from 0.20 to 0.43, respectively, in surface waters of the Chukchi/Bering Seas and the North Pacific Ocean. The concentration and condensation degree of DBC in the Chukchi/Bering Seas were higher and more variable than those in the subarctic and subtropical North Pacific, which implies that the major factors controlling DBC distribution were different in these marine provinces. In the Chukchi/Bering Seas, the DBC concentration was negatively correlated to salinity but positively correlated to chromophoric dissolved organic matter (CDOM) quantity and total dissolved lignin phenol concentration estimated by CDOM parameters. These correlations indicated that the possible major source of DBC in the Chukchi/Bering Seas was Arctic rivers. However, in the North Pacific, where riverine inputs are negligible for most sampling sites, DBC was possibly derived from the atmosphere. Although spectral slopes of CDOM at 275-295 nm (an index of the photodegradation degree of CDOM) differed widely between the subarctic and subtropical North Pacific, the concentration and condensation degrees of DBC were similar between the subarctic and subtropical North Pacific, which suggests that photodegradation was not the only major factor controlling DBC distribution. Therefore, DBC distributions of the

  8. Arctic fox (Alopex lagopus) from the North Sea

    NARCIS (Netherlands)

    Langeveld, Bram W.; Mol, Dick; van der Plicht, Hans

    2018-01-01

    The first record of arctic fox Alopex lagopus (Linnaeus, 1758) from the Eurogeul area (North Sea) is reported based on a distal humerus fragment collected by private collectors from dredged sediments on ‘De Zandmotor’. It was radiocarbon dated to 29,900 + 550/- 490 BP (GrA-69520), which is younger

  9. Analysis of North Sea Offshore Wind Power Variability

    NARCIS (Netherlands)

    Buatois, A.; Gibescu, M.; Rawn, B.G.; Van der Meijden, M.A.M.M.

    2014-01-01

    This paper evaluates, for a 2030 scenario, the impact on onshore power systems in terms of the variability of the power generated by 81 GW of offshore wind farms installed in the North Sea. Meso-scale reanalysis data are used as input for computing the hourly power production for offshore wind

  10. The caesium 137 content in the water of the North Sea during the years 1969 to 1975

    International Nuclear Information System (INIS)

    Kautsky, H.

    1976-01-01

    In April 1975, about 34,000 Ci Caesium 137 in a water mass of about 30,500 km 3 was found in the area of the North Sea that we investigated between 51 0 N to 60 0 N and 4 0 W to 10 0 E. This represented a mean concentration of about 1.1 Ci/km 3 or 1.1 pCi/l water. Concentration variations of between 0.44 to 2.2 pCi/l in the different areas of the North Sea were measured. As compared with ICRP Standards, 137 Cs concentrations in sea water of up to some 900 pCi/l may be viewed as a still permissible limit (IAEA, 1970). The development of the 137 Cs content in the North Sea from 1969 to 1975 is discussed. Especially, the temporal changes in concentrations in different sections of the North Sea will be compared. These clearly show the different influence in different sections of the radioactive waste waters of the three coastal European nuclear fuel reprocessing plants on the content of radioactive fission products as well as their spreading in the water of the North Sea. (orig./HP) [de

  11. Warming in the Nordic Seas, North Atlantic storms and thinning Arctic sea ice

    Science.gov (United States)

    Alexeev, Vladimir A.; Walsh, John E.; Ivanov, Vladimir V.; Semenov, Vladimir A.; Smirnov, Alexander V.

    2017-08-01

    Arctic sea ice over the last few decades has experienced a significant decline in coverage both in summer and winter. The currently warming Atlantic Water layer has a pronounced impact on sea ice in the Nordic Seas (including the Barents Sea). More open water combined with the prevailing atmospheric pattern of airflow from the southeast, and persistent North Atlantic storms such as the recent extremely strong Storm Frank in December 2015, lead to increased energy transport to the high Arctic. Each of these storms brings sizeable anomalies of heat to the high Arctic, resulting in significant warming and slowing down of sea ice growth or even melting. Our analysis indicates that the recently observed sea ice decline in the Nordic Seas during the cold season around Svalbard, Franz Joseph Land and Novaya Zemlya, and the associated heat release from open water into the atmosphere, contributed significantly to the increase in the downward longwave radiation throughout the entire Arctic. Added to other changes in the surface energy budget, this increase since the 1960s to the present is estimated to be at least 10 W m-2, which can result in thinner (up to at least 15-20 cm) Arctic ice at the end of the winter. This change in the surface budget is an important contributing factor accelerating the thinning of Arctic sea ice.

  12. Modelling thermal stratification in the North Sea: Application of a 2-D potential energy model

    DEFF Research Database (Denmark)

    Nielsen, Morten Holtegaard; St. John, Michael

    2001-01-01

    is forced with wind, dew point temperature from Ekofisk oilfield in the central North Sea, and tidal current and atmospheric radiation. The model is used to simulate the seasonal cycle of stratification in the central North Sea in the years 1988, 1989 and 1990 and is compared to density profiles...

  13. Plutonium and americium in arctic waters, the North Sea and Scottish and Irish coastal zones

    DEFF Research Database (Denmark)

    Hallstadius, L.; Aarkrog, Asker; Dahlgaard, Henning

    1986-01-01

    Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were co...

  14. Radioactive inputs to the North Sea and the Channel

    International Nuclear Information System (INIS)

    1984-01-01

    The subject is covered in sections: introduction (radioactivity; radioisotopes; discharges from nuclear establishments); data sources (statutory requirements); sources of liquid radioactive waste (figure showing location of principal sources of radioactive discharges; tables listing principal discharges by activity and by nature of radioisotope); Central Electricity Generating Board nuclear power stations; research and industrial establishments; Ministy of Defence establishments; other UK inputs of radioactive waste; total inputs to the North Sea and the Channel (direct inputs; river inputs; adjacent sea areas); conclusions. (U.K.)

  15. Formation of Barents Sea Branch Water in the north-eastern Barents Sea

    Directory of Open Access Journals (Sweden)

    Vidar S. Lien

    2013-09-01

    Full Text Available The Barents Sea throughflow accounts for approximately half of the Atlantic Water advection to the Arctic Ocean, while the other half flows through Fram Strait. Within the Barents Sea, the Atlantic Water undergoes considerable modifications before entering the Arctic Ocean through the St. Anna Trough. While the inflow area in the south-western Barents Sea is regularly monitored, oceanographic data from the outflow area to the north-east are very scarce. Here, we use conductivity, temperature and depth data from August/September 2008 to describe in detail the water masses present in the downstream area of the Barents Sea, their spatial distribution and transformations. Both Cold Deep Water, formed locally through winter convection and ice-freezing processes, and Atlantic Water, modified mainly through atmospheric cooling, contribute directly to the Barents Sea Branch Water. As a consequence, it consists of a dense core characterized by a temperature and salinity maximum associated with the Atlantic Water, in addition to the colder, less saline and less dense core commonly referred to as the Barents Sea Branch Water core. The denser core likely constitutes a substantial part of the total flow, and it is more saline and considerably denser than the Fram Strait branch as observed within the St. Anna Trough. Despite the recent warming of the Barents Sea, the Barents Sea Branch Water is denser than observed in the 1990s, and the bottom water observed in the St. Anna Trough matches the potential density at 2000 m depth in the Arctic Ocean.

  16. Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19 by multiple Soviet Union institutes (NODC Accession 0077413)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19...

  17. Transport, preservation and accumulation of organic carbon in the North Sea

    NARCIS (Netherlands)

    Haas, H. de

    1997-01-01

    This thesis contains the results of the research on the burial of organic carbon in the North Sea as it was carried out at the Netherlands Institute for Sea Research in the period 1993-1997. Carbon in the form of carbon dioxide (C02 ) is one of the major contributors to the natural greenhouse

  18. Transport, preservation and accumulation of organic carbon in the North Sea

    NARCIS (Netherlands)

    de Haas, H.

    1997-01-01

    This thesis contains the results of the research on the burial of organic carbon in the North Sea as it was carried out at the Netherlands Institute for Sea Research in the period 1993-1997. Carbon in the form of carbon dioxide (CO2 ) is one of the major contributors to the natural greenhouse

  19. Dissection of genetic architecture of grain chalk using NIR spectroscopy

    Science.gov (United States)

    Chalk is a major quality characteristic that causes grain breakage during milling and loss of crop value. In this study, we sought to elucidate the quantitatively inherited grain chalk trait in rice and to conduct genome-wide association mapping to identify SNPs and candidate genes associated with ...

  20. New insight into the microtexture of chalks from NMR analysis

    DEFF Research Database (Denmark)

    Faÿ-Gomord, Ophélie; Soete, Jeroen; Katika, Konstantina

    2016-01-01

    An integrated petrographical and petrophysical study was carried out on a set of 35 outcrop chalk samples, covering a wide range of lithologies and textures. In this study various chalk rock-types have been characterized, in terms of microtextures and porous network, by integrating both geologica...

  1. Other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from 1874-01-01 to 2005-12-31 (NCEI Accession 0144342)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144342 includes discrete sample and profile data collected from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from...

  2. Land-sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

    NARCIS (Netherlands)

    Donders, Timme; Van Helmond, Niels A.G.M.; Verreussel, Roel; Munsterman, Dirk; Veen, Johan Ten; Speijer, Robert P.; Weijers, Johan W.H.; Sangiorgi, Francesca; Peterse, Francien; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.; Lourens, Lucas; Kuhlmann, Gesa; Brinkhuis, Henk

    2018-01-01

    We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (ĝ1/4 2.6-1.8ĝ€Ma) multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of

  3. Petroleum Economist's 1993 North Sea survey

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    A survey is presented for 51 oil fields in the North Sea belonging to the United Kingdom, 17 belonging to Norway, 4 belonging to the Netherlands and 7 belonging to Denmark. Similarly data is presented for 32 gas fields belonging to the United Kingdom, 5 belonging to Norway, 42 belonging to the Netherlands, and 1 belonging to Denmark. The information given in the surveys includes the original recoverable reserves, remaining reserves, water depth, gravity, sulphur content, discovery date, start-up date, participants and production. (U.K.)

  4. Assessment of the environmental status for the North Sea and Baltic Sea

    DEFF Research Database (Denmark)

    Larsen, Martin Mørk; Fryer, Rob; Andersen, Jesper H.

    to or at background”, green for “no harmful effect to the environment” and red for unacceptable. The HELCOM goals set out in the Baltic Sea action plan are similar, “concentrations of hazardous substances close to natural levels”, “all fish safe to eat”, and “healthy wildlife”. The assessment criteria used......The two Conventions for the Baltic Sea (Helsinki, HELCOM) and the North Sea (Oslo-Paris, OSPAR) both are in the process of assessing the state of the marine environment and producing Quality Status reports for their regions for publication in 2010. These assessments will be part of the basis...... for Marine Strategy work in the EU. An overview of the time trends and status for metals, PCBs and PAHs in biota and sediment for the convention areas will be presented, and the scientific basis for the assessments and how results from different contaminant groups and wider areas are aggregated...

  5. Sensitivity of Calanus spp. copepods to environmental changes in the North Sea using life-stage structured models

    DEFF Research Database (Denmark)

    Maar, Marie; Møller, Eva Friis; Gürkan, Zeren

    2013-01-01

    Sea because it allows them to utilize the spring bloom more efficiently and independently of the timing and amount of oceanic inflow. The combination of lower temperatures, higher overwintering and oceanic inflow simulating the situation in the 1960s largely favoured C. finmarchicus and their relative......, overwintering and oceanic inflow in the North Sea. Life-stage structured models are validated against CPR data and vertical distributions north of the Dogger Bank in the North Sea for the reference year 2005. The model shows that 1) ± 2°C changes from the current level mainly influence the seasonal patterns...... and not the relative occurrence of the two species, 2) changes due to oceanic inflow mainly appeared in the northern and southern part of the North Sea connected to the NE Atlantic and not in the central part and 3) the abundance of Calanus species were very sensitive to the degree of overwintering within the North...

  6. Formulation and Implementation of a Constitutive Model for Soft Rock

    OpenAIRE

    Hickman, Randall John

    2004-01-01

    Petroleum reservoirs located in the Norwegian sector of the North Sea have undergone unexpected subsidence of great magnitude (> 10 m) during more than 30 years of petroleum recovery operations. Historical laboratory investigations have shown that the subsidence is due to the mechanical behavior and mechanical properties of chalk. Chalk behavior is characterized by elastoplasticity, including pore collapse, shear failure, and tensile failure mechanisms; rate-dependence; and pore fluid depende...

  7. Remarks on the sea level records of the north Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    variability in the tide gauge records along the coasts of the north Indian Ocean A. S. Unnikrishnan National Institute of Oceanography, Dona Paula, Goa, India 403004 e-mail: unni@nio.org Introduction Global sea-level rise has been relatively well... studied by making use of the coastal tide gauge data that are available (Woodworth and Player, 2003) through the Permanent Service for Mean Sea Level (PSMSL). However, studies on regional sea level rise have not gathered momentum, similar to those on a...

  8. The contribution of ship emissions to air pollution in the North Sea regions

    Energy Technology Data Exchange (ETDEWEB)

    Matthias, Volker, E-mail: volker.matthias@gkss.d [GKSS Research Centre Geesthacht, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany); Bewersdorff, Ines [GKSS Research Centre Geesthacht, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany); Aulinger, Armin, E-mail: armin.aulinger@gkss.d [GKSS Research Centre Geesthacht, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany); Quante, Markus, E-mail: markus.quante@gkss.d [GKSS Research Centre Geesthacht, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany)

    2010-06-15

    As a consequence of the global distribution of manufacturing sites and the increasing international division of labour, ship traffic is steadily increasing and is becoming more and more important as an origin of air pollution. This study investigates the impact of ship emissions in coastal areas of the North Sea under conditions of the year 2000 by means of a regional chemistry transport model which runs on a sufficiently high resolution to study air pollution in coastal regions. It was found that northern Germany and Denmark in summer suffer from more than 50% higher sulphate, nitrate and ammonium aerosol concentrations due to contributions from ships. The implementation of a sulphur emission control area (SECA) in the North Sea, as it was implemented at the end of 2007, directly results in reduced sulphur dioxide and sulphate aerosol concentrations while nitrate aerosol concentrations are slightly increased. - Ship emissions lead to significantly enhanced air pollution by secondary inorganic aerosols in North Sea coastal areas.

  9. Process for treating oil-chalk

    Energy Technology Data Exchange (ETDEWEB)

    1925-10-20

    A process for treating oil-chalk or similar oil-containing minerals is characterized in that the material is treated in a stream of air diluted with indifferent gases at a temperature of about 150/sup 0/ to 160/sup 0/C.

  10. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    International Nuclear Information System (INIS)

    Maruthi, Y. A.; Das, N. Lakshmana; Ramprasad, S.; Ram, S. S.; Sudarshan, M.

    2015-01-01

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk

  11. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    Energy Technology Data Exchange (ETDEWEB)

    Maruthi, Y. A., E-mail: ymjournal2014@gmail.com [Associate professor, Dept of Environmental Studies, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Das, N. Lakshmana, E-mail: nldas9@gmail.com [Professor, Dept of Physics, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Ramprasad, S., E-mail: ramprasadsurakala@gmail.com [Research Scholar, Dept of Environmental science, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Ram, S. S., E-mail: tracebio@gmail.com [Research Scholar, Dept of Trace element research, UGC-DAE Consortium Centre, Kolkata centre India (India); Sudarshan, M., E-mail: sude@alpha.iuc.res.in [Scientist-F, Dept of Trace element research, UGC-DAE Consortium Centre, Kolkata centre India (India)

    2015-08-28

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk.

  12. Temporal Variation of Iodine Isotopes in the North Sea

    DEFF Research Database (Denmark)

    He, Peng; Aldahan, Ala; Possnert, Göran

    2014-01-01

    Monitoring temporal variability of 129I in the North Sea, a relatively large reservoir of radioactive discharges from the nuclear fuel reprocessing facilities, is vital for the environmental situation in the region. New information on concentration levels and distribution of 129I and 127I and the...

  13. Seabird biomass and food consumption in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Furness, R.W.

    1984-07-01

    Calculations presented by Bourne contain some order-of-magnitude errors, and give the misleading impression that estimates of fish consumption by seabirds in the North Sea may be as low as 0.25%, or as high as 48%, of fish production, depending on the method of calculation. It is likely that the true figure is closer to 20% once the errors in Bourne's calculations are corrected, but several areas of uncertainty require further study; particularly seabird diets and foraging ranges, fish distribution and movements. Studies from other parts of the world show that seabird numbers can dramatically alter in response to changes in food abundance. Some changes result from natural perturbations and others from effects of overexploitation of fish stocks by man. Effects of overfishing seem likely to be potentially, at least as serious, as effects of oil or chemical pollution in many regions, possibly including the North Sea. 48 references.

  14. Clean-up of the sea bed in the North Sea 1996

    International Nuclear Information System (INIS)

    1997-01-01

    The petroleum activities in the North Sea have inadvertently caused some conflict with fishermen getting their trawls etc. into trash from littering of the sea bed. In the present report, the Norwegian Petroleum Directorate describes a clean-up operation undertaken in 1996 and paid by the State. A clean-up area of 1000 km 2 off Karmoey was selected. This area was mapped by side scan sonar along survey lines 300 m equidistant and a sonar range of 200 m. The sonar data were continuously interpreted by a geophysicist. Selected targets were then identified by ROV and eventually removed. Of the 59 targets examined, 11 were removed and dumped onshore. The largest part elevated was a chain cable of 9 tons. There is also a brief discussion of the compensation agreement with Norwegian fishermen. 4 figs

  15. Quantifying pelagic-benthic coupling in the North Sea: Are we asking the right question?

    DEFF Research Database (Denmark)

    Richardson, K.; Cedhagen, T.

    2002-01-01

    is devoted to obtaining more and better data describing this exchange. Efforts to quantify exchange between the water column and the sediment must continue. However, such studies will not, in themselves, lead to a quantification of pelagic-benthic coupling in the North Sea. We identify here other areas......The coupling between pelagic and benthic processes occurs through the signals sent between the water column and the seabed. Huge methodological challenges are associated with the quantification of the signals being sent between these two domains - especially in a relatively shallow and heavily...... fished region such as the North Sea where deployment of sediment traps or bottom mounted cameras or samplers is difficult. Thus, there are relatively few sites in the North Sea for which good data are available for describing pelagic-benthic (or near shore-offsbore) coupling and considerable effort...

  16. The radon-222 transfer coefficients across air-sea interface determined in the Bering Sea, the Okhotsk Sea and the North Pacific Ocean

    International Nuclear Information System (INIS)

    Kholujskij, S.N.; Anikiev, V.V.; Popov, N.I.

    1995-01-01

    Determination of velocity coefficient for gas flow transfer across the natural sea surface into the atmosphere (K v ) was attempted by means of radon method on board the SRS Academician Alexander Nesmeyanov (July-August 1992). The measurements were conducted in the Bering Sea, the Okhotsk Sea and in the North Pacific Ocean. It is shown that the total range of the K v observed values equaled from 1.8 up to 5.4 m.day, which is within the known limits for other regions of the world ocean. 9 refs., 1 fig

  17. Twelve tips for the production of digital chalk-talk videos.

    Science.gov (United States)

    Rana, Jasmine; Besche, Henrike; Cockrill, Barbara

    2017-06-01

    Increasingly over the past decade, faculty in medical and graduate schools have received requests from digital millennial learners for concise faculty-made educational videos. At our institution, over the past couple of years alone, several hundred educational videos have been created by faculty who teach in a flipped-classroom setting of the pre-clinical medical school curriculum. Despite the appeal and potential learning benefits of digital chalk-talk videos first popularized by Khan Academy, we have observed that the conceptual and technological barriers for creating chalk-talk videos can be high for faculty. To this end, this tips article offers an easy-to-follow 12-step conceptual framework to guide at-home production of chalk-talk educational videos.

  18. Contrasting records of sea-level change in the eastern and western North Atlantic during the last 300 years

    Science.gov (United States)

    Long, A. J.; Barlow, N. L. M.; Gehrels, W. R.; Saher, M. H.; Woodworth, P. L.; Scaife, R. G.; Brain, M. J.; Cahill, N.

    2014-02-01

    We present a new 300-year sea-level reconstruction from a salt marsh on the Isle of Wight (central English Channel, UK) that we compare to other salt-marsh and long tide-gauge records to examine spatial and temporal variability in sea-level change in the North Atlantic. Our new reconstruction identifies an overall rise in relative sea level (RSL) of c. 0.30 m since the start of the eighteenth century at a rate of 0.9±0.3 mm yr. Error-in-variables changepoint analysis indicates that there is no statistically significant deviation from a constant rate within the dataset. The reconstruction is broadly comparable to other tide-gauge and salt-marsh records from the European Atlantic, demonstrating coherence in sea level in this region over the last 150-300 years. In contrast, we identify significant differences in the rate and timing of RSL with records from the east coast of North America. The absence of a strong late 19th/early 20th century RSL acceleration contrasts with that recorded in salt marsh sediments along the eastern USA coastline, in particular in a well-dated and precise sea-level reconstruction from North Carolina. This suggests that this part of the North Carolina sea level record represents a regionally specific sea level acceleration. This is significant because the North Carolina record has been used as if it were globally representative within semi-empirical parameterisations of past and future sea-level change. We conclude that regional-scale differences of sea-level change highlight the value of using several, regionally representative RSL records when calibrating and testing semi-empirical models of sea level against palaeo-records. This is because by using records that potentially over-estimate sea-level rise in the past such models risk over-estimating sea-level rise in the future.

  19. Chalk effect on PVC cross-linking under irradiation; Vliyanie mela na sshivanie PVKh pri obluchenii

    Energy Technology Data Exchange (ETDEWEB)

    Chudinova, V V; Guzeev, V V; Mozzhukhin, V B; Pomerantseva, Eh G; Nozrina, F D; Zhil` tsov, V V; Zubov, V P

    1994-12-31

    Effect of nonmodified and modified chalk on curing degree of polymer matrix was studied under-irradiation of PVC-compositions. Films of the compositions (100 mass part 7 PVC, 0-100 mas.part of chalk, 2.5 - lead sulfate, 1.5 - lead stearate and 0.3 - glycerin) were irradiated up to absorbed dose 0.1 MGy in an inert medium. Content of gel-fraction after boiling in THF was determined with use of IR spectroscopy. It was established, that intensive dehydrochlorination and polymer curing took place on chalk particle surface. Network fixed strongly chalk particles. However, chalk inhibited processes of dehydrochlorination and PVC curing, increasing amount of noncured PVC in polymer matrix.

  20. Independent companies in the North Sea - exploration and operations opportunities

    International Nuclear Information System (INIS)

    Greentree, C.

    1992-01-01

    The North Sea was the launching pad for many independent oil companies, particularly through exploration success in the UK and the Netherlands. Norway has an excellent history of oil exploration but, for the independents, the onerous tax regime, long lead times, and terms of trade are simply not conducive to the higher rate of return demanded by shareholders of independent E and P companies in exchange for shouldering the heavy burden of risk. The UK in particular has pursued imaginative licensing, tax and legislative policies which have allowed the independents an opportunity to participate and grow. The attraction of the UK is clearly reflected by the constant arrival of new entrants, even at this stage of maturity. This was demonstrated in the recent round of license awards. Such has been the success of the independents in the UK that, beginning with virtually nothing, they now hold a net 28% of the UK North Sea acreage, and a net 25% of its oil reserves. Equally, the independents play an important role in ensuring the comprehensive exploration of the offshore areas. Because of size and significance, a prime objective of the independents will remain the early evaluation, through drilling, and development of offshore interests to generate a financial return. This paper addresses the question of how independent companies can expand in the North Sea when the size and quality of new range acreage available through new license awards is reducing. (author)

  1. The North Sea Bird Club

    International Nuclear Information System (INIS)

    Doyle, P.A.T.; Gorman, M.L.; Patterson, I.J.; Howe, S.

    1991-01-01

    This paper reports that the creation of a club for the purpose of encouraging oil and gas workers to watch birds may not at first seem a viable proposition. To the layperson, birds offshore conjures up an image of hundreds of seagulls following fishing boats, and very little else. Also, the act of birdwatching is not seen as a typical offshore worker's activity. Anyone who has worked on an installation offshore and who has any interest in wildlife will be aware of the occasional presence of land-birds. Two decades ago, prompted by some keen offshore workers, a single oil company set up a monitoring program, which quickly became popular with a number of its employees. Birds seem offshore were recorded on data forms and collected together. At this stage the club was purely another recreation facility; however, when the data were collated it was soon realized that installations offshore were being used as staging posts by birds on migration, and that the information being collected would be of great interest in the study of bird movements. All over Britain, at strategic points on the coastline, there are bird observatories which record the arrival and departure of migrating birds. The presence of several hundred solid structures up and down the North Sea, which are used by birds en route, represents a huge, unique bird observatory, capable of uncovering facts about bird migration which have long eluded land-based scientists. Eleven years ago, the North Sea Bird Club began, composed of eight member companies, a recorder from Aberdeen University and a representative from the Nature Conservancy Council. The club received data from 41 installations, and the recorder collated these on Aberdeen University's computer and produced an annual report of sightings

  2. Radiological implications from the temporal development of radioactivity in marine food from the North Sea

    International Nuclear Information System (INIS)

    Kanisch, G.; Nagel, G.; Krueger, A.; Kellermann, H.-J.

    2000-01-01

    A subject of the revision of authorised limits in 1994 for the discharge of liquid radioactive waste by the reprocessing plant Sellafield (UK) was an increase of these limits for certain radionuclides ( 3 H, 14 C, 60 Co, 99 Tc and 129 I). It is investigated now how the radioactivity in marine biota from the North Sea and subsequently the public radiation exposure of seafood consumers has developed in the years since 1994. This is based on a compartment model for dispersion in the North-East Atlantic. Discharges from the reprocessing plants Dounreay (UK) and La Hague (F) are included in the assessment. It is deduced that about 60% of 137 Cs in the North Sea originate presently in the remobilisation of old Sellafield discharges from the Irish Sea sediment. A comparison with measured biota data shows that the model is conservative in most cases. The public radiation exposure (artificial radionuclides) from ingestion of fish, crustaceans and molluscs from the central North Sea as the sum over 12 considered radionuclides has decreased from 1992 to 1998 from 0.13 to 0.08 μSv y -1 . (orig.)

  3. Elastic and electric properties of North Sea Chalk

    DEFF Research Database (Denmark)

    Olsen, Casper

    bjergartsfysiske modeller til forudsigelse af Biot’s koefficient ud fra porøsitet og én lydhastighed og hans resultater tyder på at Berryman’s udbredte ”Selfconsistent Model” er mindre velegnet til det formål, mens at de simplere Isoframe og Bound-averaging metoder giver bedre resultater. Dvorkin’s partikel...

  4. Avian Influenza Ecology in North Atlantic Sea Ducks: Not All Ducks Are Created Equal

    Science.gov (United States)

    Hall, Jeffrey S.; Russell, Robin E.; Franson, J. Christian; Soos, Catherine; Dusek, Robert J.; Allen, R. Bradford; Nashold, Sean W.; TeSlaa, Joshua L.; Jónsson, Jón Eínar; Ballard, Jennifer R.; Harms, Naomi Jane; Brown, Justin D.

    2015-01-01

    Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology. PMID:26677841

  5. Avian influenza ecology in North Atlantic sea ducks: Not all ducks are created equal

    Science.gov (United States)

    Hall, Jeffrey S.; Russell, Robin E.; Franson, J. Christian; Soos, Catherine; Dusek, Robert J.; Allen, R. Bradford; Nashold, Sean W.; Teslaa, Joshua L.; Jónsson, Jón Einar; Ballard, Jennifer R.; Harms, Naomi Jnae; Brown, Justin D.

    2015-01-01

    Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology.

  6. Stochastic modelling of porosity using seismic impedances on a volume of chalk in the Dan Field

    Energy Technology Data Exchange (ETDEWEB)

    Vejbaek, O.V.

    1995-12-31

    Seismic impedances calculated from logs show very good correlation to log porosities in wells penetrating the chalk reservoir in the Dan Field, Danish North Sea. This is the basis for an attempt to use seismic impedances derived from inversion as soft data for geostatistical reservoir characterization. The study focusses on porosity description of the Maastrichtian chalk reservoir unit, laterally restricted to an area covered by a subset of a 3D seismic survey. This seismic volume was inverted using the ISIS software producing a volume of seismic impedances. Spatial porosity realizations are produced using a gaussian collocated co-simulation algorithm, where well log porosities constitute the hard data input and seismic impedances are the soft data input. The simulated volume measures 1400 m x 1525 m x 102 m and is oriented parallel to lines and cross lines in the seismic dataset. Simulated blocks measures 25 m x 25 m x 6 m equivalent to twice the line and trace spacing, and approximately equivalent to the seismic sample rate. The correlation coefficient between log porosities and impedances calculated from logs alone are shown to be misleading since they suggest unrealistic high coefficients. However, the actual data used, namely inversion derived impedances and log porosities, still show correlation coefficients in the order of -0,45, which is quite sufficient to make the inversion results very useful. It is remarkable that the calculated correlation coefficient is based on 15 wells, and the inversion is based on only one well. The negative correlation coefficient indicate that high impedances correspond to low porosities and vice-versa. The impedance data indicate the level of average porosities at locations between wells. The fine structure is produced by the geostatistic process, with averages constrained by seismic impedances. The seismic impedances derived from the inversion process are thus shown to constitute useful primary data to constrain reservoir

  7. Shifts in North Sea forage fish productivity and potential fisheries yield

    DEFF Research Database (Denmark)

    Worsøe Clausen, Lotte; Rindorf, Anna; van Deurs, Mikael

    2018-01-01

    productivity. Furthermore, from an ecosystem-based fisheries management perspective, a link between functional complementarity and productivity, indicates that ecosystem resilience may decline with productivity. Based on this, we advise that system productivity, perhaps monitored as forage fish growth, becomes......1. Forage fish populations support large scale fisheries and are key components of marine ecosystems across the world, linking secondary production to higher trophic levels. While climate-induced changes in the North Sea zooplankton community are described and documented in literature......, the associated bottom-up effects and consequences for fisheries remain largely unidentified. 2. We investigated the temporal development in forage fish productivity and the associated influence on fisheries yield of herring, sprat, Norway pout and sandeel in the North Sea. Using principal component analysis, we...

  8. Ekofisk chalk: core measurements, stochastic reconstruction, network modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, Saifullah

    2002-07-01

    This dissertation deals with (1) experimental measurements on petrophysical, reservoir engineering and morphological properties of Ekofisk chalk, (2) numerical simulation of core flood experiments to analyze and improve relative permeability data, (3) stochastic reconstruction of chalk samples from limited morphological information, (4) extraction of pore space parameters from the reconstructed samples, development of network model using pore space information, and computation of petrophysical and reservoir engineering properties from network model, and (5) development of 2D and 3D idealized fractured reservoir models and verification of the applicability of several widely used conventional up scaling techniques in fractured reservoir simulation. Experiments have been conducted on eight Ekofisk chalk samples and porosity, absolute permeability, formation factor, and oil-water relative permeability, capillary pressure and resistivity index are measured at laboratory conditions. Mercury porosimetry data and backscatter scanning electron microscope images have also been acquired for the samples. A numerical simulation technique involving history matching of the production profiles is employed to improve the relative permeability curves and to analyze hysteresis of the Ekofisk chalk samples. The technique was found to be a powerful tool to supplement the uncertainties in experimental measurements. Porosity and correlation statistics obtained from backscatter scanning electron microscope images are used to reconstruct microstructures of chalk and particulate media. The reconstruction technique involves a simulated annealing algorithm, which can be constrained by an arbitrary number of morphological parameters. This flexibility of the algorithm is exploited to successfully reconstruct particulate media and chalk samples using more than one correlation functions. A technique based on conditional simulated annealing has been introduced for exact reproduction of vuggy

  9. Impedance imaging in core analysis. Imaging of phase distributions in samples of natural cores of North Sea chalk containing conducting as well as non-conducting fluids. Part: 1-3

    Energy Technology Data Exchange (ETDEWEB)

    Laursen, S. [DTU, Inst. for Kemi (Denmark)] Moeller Nielsen, C. [DTU, Inst. for Energiteknik (Denmark)

    1997-12-31

    The present report documents the efforts to develop an impedance method for determining the distribution of the water saturation in a chalk core sample. Measurement of this distribution during a displacement process will make it possible to make numerical simulations of the process which may in turn reveal important rock parameters. The impedance method is one among other methods to determine saturation profiles in a research programme on rock parameters with participants from Danmarks Tekniske Universitet, DTU, and Danmarks og Groenlands Geologiske Undersoegelse, GEUS. The other methods investigated are nmr-scanning and {gamma}-logging. (au)

  10. The effect of chalk on the finger-hold friction coefficient in rock climbing.

    Science.gov (United States)

    Amca, Arif Mithat; Vigouroux, Laurent; Aritan, Serdar; Berton, Eric

    2012-11-01

    The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were performed. Participants hung from holds which were fixed on a specially designed hang board. The inclination of the hang board was progressively increased until the climber's hand slipped from the holds. The angle of the hang board was simultaneously recorded by using a gyroscopic sensor and the friction coefficient was calculated at the moment of slip. The results showed that there was a significant positive effect of chalk on the coefficient of friction (+18.7% on limestone and +21.6% on sandstone). Moreover sandstone had a higher coefficient of friction than limestone (+15.6% without chalk, +18.4% with chalk). These results confirmed climbers' belief that chalk enhances friction. However, no correlation with humidity/temperature and friction coefficient was noted which suggested that additional parameters should be considered in order to understand the effects of climate on finger friction in rock climbing.

  11. Simulated wind-generated inertial oscillations compared to current measurements in the northern North Sea

    Science.gov (United States)

    Bruserud, Kjersti; Haver, Sverre; Myrhaug, Dag

    2018-04-01

    Measured current speed data show that episodes of wind-generated inertial oscillations dominate the current conditions in parts of the northern North Sea. In order to acquire current data of sufficient duration for robust estimation of joint metocean design conditions, such as wind, waves, and currents, a simple model for episodes of wind-generated inertial oscillations is adapted for the northern North Sea. The model is validated with and compared against measured current data at one location in the northern North Sea and found to reproduce the measured maximum current speed in each episode with considerable accuracy. The comparison is further improved when a small general background current is added to the simulated maximum current speeds. Extreme values of measured and simulated current speed are estimated and found to compare well. To assess the robustness of the model and the sensitivity of current conditions from location to location, the validated model is applied at three other locations in the northern North Sea. In general, the simulated maximum current speeds are smaller than the measured, suggesting that wind-generated inertial oscillations are not as prominent at these locations and that other current conditions may be governing. Further analysis of the simulated current speed and joint distribution of wind, waves, and currents for design of offshore structures will be presented in a separate paper.

  12. Sensitivity of modeled atmospheric nitrogen species and nitrogen deposition to variations in sea salt emissions in the North Sea and Baltic Sea regions

    Directory of Open Access Journals (Sweden)

    D. Neumann

    2016-03-01

    Full Text Available Coarse sea salt particles are emitted ubiquitously from the ocean surface by wave-breaking and bubble-bursting processes. These particles impact the atmospheric chemistry by affecting the condensation of gas-phase species and, thus, indirectly the nucleation of new fine particles, particularly in regions with significant air pollution. In this study, atmospheric particle concentrations are modeled for the North Sea and Baltic Sea regions in northwestern Europe using the Community Multiscale Air Quality (CMAQ modeling system and are compared to European Monitoring and Evaluation Programme (EMEP measurement data. The sea salt emission module is extended by a salinity-dependent scaling of the sea salt emissions because the salinity in large parts of the Baltic Sea is very low, which leads to considerably lower sea salt mass emissions compared to other oceanic regions. The resulting improvement in predicted sea salt concentrations is assessed. The contribution of surf zone emissions is considered separately. Additionally, the impacts of sea salt particles on atmospheric nitrate and ammonium concentrations and on nitrogen deposition are evaluated. The comparisons with observational data show that sea salt concentrations are commonly overestimated at coastal stations and partly underestimated farther inland. The introduced salinity scaling improves the predicted Baltic Sea sea salt concentrations considerably. The dates of measured peak concentrations are appropriately reproduced by the model. The impact of surf zone emissions is negligible in both seas. Nevertheless, they might be relevant because surf zone emissions were cut at an upper threshold in this study. Deactivating sea salt leads to minor increases in NH3 +  NH4+ and HNO3 +  NO3− and a decrease in NO3− concentrations. However, the overall effect on NH3 +  NH4+ and HNO3 +  NO3− concentrations is smaller than the deviation from the measurements. Nitrogen wet deposition is

  13. Sea-ice evaluation of NEMO-Nordic 1.0: a NEMO-LIM3.6-based ocean-sea-ice model setup for the North Sea and Baltic Sea

    Science.gov (United States)

    Pemberton, Per; Löptien, Ulrike; Hordoir, Robinson; Höglund, Anders; Schimanke, Semjon; Axell, Lars; Haapala, Jari

    2017-08-01

    The Baltic Sea is a seasonally ice-covered marginal sea in northern Europe with intense wintertime ship traffic and a sensitive ecosystem. Understanding and modeling the evolution of the sea-ice pack is important for climate effect studies and forecasting purposes. Here we present and evaluate the sea-ice component of a new NEMO-LIM3.6-based ocean-sea-ice setup for the North Sea and Baltic Sea region (NEMO-Nordic). The setup includes a new depth-based fast-ice parametrization for the Baltic Sea. The evaluation focuses on long-term statistics, from a 45-year long hindcast, although short-term daily performance is also briefly evaluated. We show that NEMO-Nordic is well suited for simulating the mean sea-ice extent, concentration, and thickness as compared to the best available observational data set. The variability of the annual maximum Baltic Sea ice extent is well in line with the observations, but the 1961-2006 trend is underestimated. Capturing the correct ice thickness distribution is more challenging. Based on the simulated ice thickness distribution we estimate the undeformed and deformed ice thickness and concentration in the Baltic Sea, which compares reasonably well with observations.

  14. Advanced waterflooding in chalk reservoirs: Understanding of underlying mechanisms

    DEFF Research Database (Denmark)

    Zahid, Adeel; Sandersen, Sara Bülow; Stenby, Erling Halfdan

    2011-01-01

    Over the last decade, a number of studies have shown SO42−, Ca2+ and Mg2+ to be potential determining ions, which may be added to the injected brine for improving oil recovery during waterflooding in chalk reservoirs. However the understanding of the mechanism leading to an increase in oil recove...... of a microemulsion phase could be the possible reasons for the observed increase in oil recovery with sulfate ions at high temperature in chalk reservoirs besides the mechanism of the rock wettability alteration, which has been reported in most previous studies.......Over the last decade, a number of studies have shown SO42−, Ca2+ and Mg2+ to be potential determining ions, which may be added to the injected brine for improving oil recovery during waterflooding in chalk reservoirs. However the understanding of the mechanism leading to an increase in oil recovery...

  15. Monitoring plastic ingestion by the northern fulmar Fulmarus glacialis in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Franeker, Jan A. van, E-mail: Jan.vanfraneker@wur.nl [IMARES Institute for Marine Resources and Ecosystem Studies, Wageningen-UR, PO Box 167, 1790AD Den Burg, Texel (Netherlands); Blaize, Christine [Le CHENE, Centre de Sauvegarde de la Faune Sauvage et Musee de la Nature, 12 Rue du Musee, F-76190 Allouville-Bellefosse (France); Danielsen, Johannis [Norouri i Sundum 7, FO-410 Kollafjorour (Faroe Islands); Fairclough, Keith [Fairclough Ecological Orkney FEO Viewforth, Swannay by Evie, Orkney, KW17 2NR, Scotland (United Kingdom); Gollan, Jane [Kermouroux, FR-56 470 Saint Philibert (France); Guse, Nils [Research and Technology Centre West coast FTZ, University of Kiel, Hafentoern 1, D-25761 Buesum (Germany); Hansen, Poul-Lindhard [Naturhistorisk Museum Skagen, Skagen Naturcenter, Flagbakkevej 30, DK-9990 Skagen (Denmark); Heubeck, Martin [University of Aberdeen (SOTEAG), Sumburgh Head Lighthouse, Virkie, Shetland ZE3 9JN, Scotland (United Kingdom); Jensen, Jens-Kjeld [Zoological conservator, I Geilini 37, FO-270 Nolsoy (Faroe Islands); Le Guillou, Gilles [Groupe Ornithologique Normand, 118 route d' ORCHER, F-76700 Gonfreville l' Orcher (France); Olsen, Bergur [Faroe Marine Research Institute c/o Natturugripasavnio, Futalag 40, FO-100 Torshavn (Faroe Islands); Olsen, Kare-Olav [Postveien 43, N-4563 Borhaug (Norway); Pedersen, John [Skagen Uddannelsescenter SUC, Vestmolen 15, DK-9990 Skagen (Denmark); Stienen, Eric W.M. [Research Institute for Nature and Forest, Kliniekstraat 25, B-1070 Brussels (Belgium); Turner, Daniel M. [9 Haswell Gardens, North Shields, Tyne and Wear, NE30 2DP, England (United Kingdom)

    2011-10-15

    The abundance of plastics in stomachs of northern fulmars from the North Sea is used in the OSPAR Ecological Quality Objective (EcoQO) for marine litter. The preliminary EcoQO defines acceptable ecological quality as the situation where no more than 10% of fulmars exceed a critical level of 0.1 g of plastic in the stomach. During 2003-2007, 95% of 1295 fulmars sampled in the North Sea had plastic in the stomach (on average 35 pieces weighing 0.31 g) and the critical level of 0.1 g of plastic was exceeded by 58% of birds, with regional variations ranging from 48 to 78%. Long term data for the Netherlands since the 1980s show a decrease of industrial, but an increase of user plastics, with shipping and fisheries as the main sources. The EcoQO is now also used as an indicator for Good Environmental Status in the European Marine Strategy Framework Directive. - Highlights: > Trends in marine debris can be monitored by plastics in stomachs of seabirds. > In the North Sea 95% of Fulmars has plastic in the stomach (35 particles; 0.31 g). > The policy target is that less than 10% of Fulmars has over 0.1 g of plastic. > Currently 58% of North Sea fulmars exceeds the 0.1 g critical limit. > Over the past 30 years industrial plastics decreased and user plastic increased. - Trends and patterns in the abundance of plastics in northern fulmar stomachs show that seabirds can be a valuable tool for monitoring marine litter.

  16. Monitoring plastic ingestion by the northern fulmar Fulmarus glacialis in the North Sea

    International Nuclear Information System (INIS)

    Franeker, Jan A. van; Blaize, Christine; Danielsen, Johannis; Fairclough, Keith; Gollan, Jane; Guse, Nils; Hansen, Poul-Lindhard; Heubeck, Martin; Jensen, Jens-Kjeld; Le Guillou, Gilles; Olsen, Bergur; Olsen, Kare-Olav; Pedersen, John; Stienen, Eric W.M.; Turner, Daniel M.

    2011-01-01

    The abundance of plastics in stomachs of northern fulmars from the North Sea is used in the OSPAR Ecological Quality Objective (EcoQO) for marine litter. The preliminary EcoQO defines acceptable ecological quality as the situation where no more than 10% of fulmars exceed a critical level of 0.1 g of plastic in the stomach. During 2003-2007, 95% of 1295 fulmars sampled in the North Sea had plastic in the stomach (on average 35 pieces weighing 0.31 g) and the critical level of 0.1 g of plastic was exceeded by 58% of birds, with regional variations ranging from 48 to 78%. Long term data for the Netherlands since the 1980s show a decrease of industrial, but an increase of user plastics, with shipping and fisheries as the main sources. The EcoQO is now also used as an indicator for Good Environmental Status in the European Marine Strategy Framework Directive. - Highlights: → Trends in marine debris can be monitored by plastics in stomachs of seabirds. → In the North Sea 95% of Fulmars has plastic in the stomach (35 particles; 0.31 g). → The policy target is that less than 10% of Fulmars has over 0.1 g of plastic. → Currently 58% of North Sea fulmars exceeds the 0.1 g critical limit. → Over the past 30 years industrial plastics decreased and user plastic increased. - Trends and patterns in the abundance of plastics in northern fulmar stomachs show that seabirds can be a valuable tool for monitoring marine litter.

  17. Seamount physiography and biology in North-East Atlantic and Mediterranean Sea

    OpenAIRE

    T. Morato; K. Ø. Kvile; G. H. Taranto; F. Tempera; B. E. Narayanaswamy; D. Hebbeln; G. Menezes; C. Wienberg; R. S. Santos; T. J. Pitcher

    2012-01-01

    This work aims at characterising the seamount physiography and biology in the OSPAR Convention limits (North-East Atlantic Ocean) and Mediterranean Sea. We first inferred potential abundance, location and morphological characteristics of seamounts, and secondly, summarized the existing biological, geological and oceanographic in-situ research, identifying examples of well-studied seamounts. Our study showed that the seamount population in the OSPAR area (North-East Atlantic) and in Mediterran...

  18. Polyunsaturated fatty acids in various macroalgal species from north Atlantic and tropical seas

    OpenAIRE

    van Ginneken, Vincent JT; Helsper, Johannes PFG; de Visser, Willem; van Keulen, Herman; Brandenburg, Willem A

    2011-01-01

    Abstract Background In this study the efficacy of using marine macroalgae as a source for polyunsaturated fatty acids, which are associated with the prevention of inflammation, cardiovascular diseases and mental disorders, was investigated. Methods The fatty acid (FA) composition in lipids from seven sea weed species from the North Sea (Ulva lactuca, Chondrus crispus, Laminaria hyperborea, Fucus serratus, Undaria pinnatifida, Palmaria palmata, Ascophyllum nodosum) and two from tropical seas (...

  19. The occurrence of the Flying Fish, Hirundichthys speculiger (Valenciennes, 1847), in the North Sea (Pisces, Atheriniformes, Exocoetidae)

    NARCIS (Netherlands)

    Boer, P.; Nijssen, H.

    1972-01-01

    The occurrence of a specimen of the Flying Fish Hirundichthys speculiger (Valenciennes, 1847) in the North Sea is recorded. This is the first record of a member of the family Exocoetidae in the coastal waters of the Netherlands. The specimen is illustrated, and its occurrence in the North Sea is

  20. Water scaling in the North Sea oil and gas fields and scale prediction: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, M

    1997-12-31

    Water-scaling is a common and major production chemistry problem in the North Sea oil and gas fields and scale prediction has been an important means to assess the potential and extent of scale deposition. This paper presents an overview of sulphate and carbonate scaling problems in the North Sea and a review of several widely used and commercially available scale prediction software. In the paper, the water chemistries and scale types and severities are discussed relative of the geographical distribution of the fields in the North Sea. The theories behind scale prediction are then briefly described. Five scale or geochemical models are presented and various definitions of saturation index are compared and correlated. Views are the expressed on how to predict scale precipitation under some extreme conditions such as that encountered in HPHT reservoirs. 15 refs., 7 figs., 9 tabs.

  1. The European anchovy (Engraulis encrasicolus) increase in the North Sea

    NARCIS (Netherlands)

    Raab, K.E.

    2013-01-01

    Small pelagic fish such as anchovy are of high socio-economic importance worldwide. They are known for strong fluctuations in abundance, for which the mechanisms are not always understood. European anchovy (Engraulis encrasicolus) increased its population in the North Sea starting in

  2. The maximum significant wave height in the Southern North Sea

    NARCIS (Netherlands)

    Bouws, E.; Tolman, H.L.; Holthuijsen, L.H.; Eldeberky, Y.; Booij, N.; Ferier, P.

    1995-01-01

    The maximum possible wave conditions along the Dutch coast, which seem to be dominated by the limited water depth, have been estimated in the present study with numerical simulations. Discussions with meteorologists suggest that the maximum possible sustained wind speed in North Sea conditions is

  3. Persistent and emerging micro-organic contaminants in Chalk groundwater of England and France

    International Nuclear Information System (INIS)

    Lapworth, D.J.; Baran, N.; Stuart, M.E.; Manamsa, K.; Talbot, J.

    2015-01-01

    The Chalk aquifer of Northern Europe is an internationally important source of drinking water and sustains baseflow for surface water ecosystems. The areal distribution of microorganic (MO) contaminants, particularly non-regulated emerging MOs, in this aquifer is poorly understood. This study presents results from a reconnaissance survey of MOs in Chalk groundwater, including pharmaceuticals, personal care products and pesticides and their transformation products, conducted across the major Chalk aquifers of England and France. Data from a total of 345 sites collected during 2011 were included in this study to provide a representative baseline assessment of MO occurrence in groundwater. A suite of 42 MOs were analysed for at each site including industrial compounds (n = 16), pesticides (n = 14) and pharmaceuticals, personal care and lifestyle products (n = 12). Occurrence data is evaluated in relation to land use, aquifer exposure, well depth and depth to groundwater to provide an understanding of vulnerable groundwater settings. - Highlights: • Broad range of microorganics detected in Chalk groundwater in England and France. • Plasticisers, pesticides, BPA and THM detected at the highest concentrations. • Pesticides higher in outcrop Chalk, caffeine and BPA at concealed sites. • Occurrences show some relationship to land use, borehole depth and water level. - Broad screening reveals for the first time the extent of emerging microorganic pollution in Chalk groundwater sources across England and France

  4. Causes of accelerating sea level on the East Coast of North America.

    Science.gov (United States)

    Davis, James L; Vinogradova, Nadya T

    2017-05-28

    The tide-gauge record from the North American East Coast reveals significant accelerations in sea level starting in the late twentieth century. The estimated post-1990 accelerations range from near zero to ∼0.3 mm yr -2 . We find that the observed sea level acceleration is well modeled using several processes: mass change in Greenland and Antarctica as measured by the Gravity Recovery and Climate Experiment satellites; ocean dynamic and steric variability provided by the GECCO2 ocean synthesis; and the inverted barometer effect. However, to achieve this fit requires estimation of an admittance for the dynamical and steric contribution, possibly due to the coarse resolution of this analysis or to simplifications associated with parameterization of bottom friction in the shallow coastal areas. The acceleration from ice loss alone is equivalent to a regional sea level rise in one century of 0.2 m in the north and 0.75 m in the south of this region.

  5. Structural geology of the North and Middle Caspian sea on the new geophysical data interpretation

    International Nuclear Information System (INIS)

    Boris, V.S; Rais, V.Sh; Victor, L.U

    2002-01-01

    Full text:A structural and tectonic map of the North and Middle Caspian Sea is made on the basis of seismic and other geological and geophysical data analysis. According to the plotting results the total amplitude range of the heterogeneous basement depths are in the North Caspian Sea (Ukatnensky depression-over 12 km and Prorva depression-over 16 km). In the middle Caspian Sea the deppest basement point is supposed in Sulak basin (over 12 km). The least basement depths are marked in Karpinsky ridge,Buzachinky and Karabogazsky arches (1-3 km). On the whole the morphology and structure of the basement confirms the conclusion previously made by many researches that the Caspian Sea is a heterogeneous depression superimposed on the junction of regional tectonic elements of various ages.The ancient East-European platform represented by Pricaspiisky depression (Donetsko-Astrakhanskaya fault system limits the latter in the south) is situated on the North. The middle Caspian Sea is occupied with the offshore continuation of Terek-Caspian foredeep is represented by Sulak basin clearly limited in the south by a system of upthrusts and thrusts falling under North Caucasus foreland.Geological interpretation of the Yuzhmorgeologiya Center new geophysical data allows making an assumption about the biohermexistence within TriassicSea sediments on Kuma-Manychsky depression offshore continuation. Seismic exploration works show strike-slip faults and thrust structure development within the sedimentary cover on the offshore continuation of Karpinsky ridge.Some strike-slipped blocks are separated by left-side shifts of the northeast stretch.The pool location at the left-side (east) blocks of the shift areas is marked.

  6. Vertical nutrient fluxes, turbulence and the distribution of chlorophyll a in the north-eastern North Sea

    Science.gov (United States)

    Bendtsen, Jørgen; Richardson, Katherine

    2017-04-01

    During summer the northern North Sea is characterized by nutrient rich bottom water masses and nutrient poor surface layers. This explains the distribution of chlorophyll a in the water column where a subsurface maximum, referred to as the deep chlorophyll maximum (DCM), often is present during the growth season. Vertical transport of nutrients between bottom water masses and the well lit surface layer stimulates phytoplankton growth and this generally explains the location of the DCM. However, a more specific understanding of the interplay between vertical transports, nutrient fluxes and phytoplankton abundance is required for identifying the nature of the vertical transport processes, e.g the role of advection versus vertical turbulent diffusion or the role of localized mixing associated with mesoscale eddies. We present results from the VERMIX study in the north-eastern North Sea where nutrients, chlorophyll a and turbulence profiles were measured along five north-south directed transects in July 2016. A high-resolution sampling program, with horizontal distances of 1-10 km between CTD-stations, resolved the horizontal gradients of chlorophyll a across the steep bottom slope from the relatively shallow central North Sea ( 50-80 m) towards the deep Norwegian Trench (>700 m). Low oxygen concentrations in the bottom water masses above the slope indicated enhanced biological production where vertical mixing would stimulate phytoplankton growth around the DCM. Measurements of variable fluorescence (Fv/Fm) showed elevated values in the DCM which demonstrates a higher potential for electron transport in the Photosystem II in the phytoplankton cells, i.e. an indication of nutrient-rich conditions favorable for phytoplankton production. Profiles of the vertical shear and microstructure of temperature and salinity were measured by a VMP-250 turbulence profiler and the vertical diffusion of nutrients was calculated from the estimated vertical turbulent diffusivity and the

  7. Anchovy Engraulis encrasicolus diet in the North and Baltic Seas

    NARCIS (Netherlands)

    Raab, K.E.; Nagelkerke, L.A.J.; Boerée, L.A.J.; Rijnsdorp, A.D.; Temming, A.; Dickey-Collas, M.

    2011-01-01

    The diet of anchovy (Engraulis encrasicolus) in the North and Baltic Seas was studied using stomach analysis from four sampling events in different areas. Zooplanktivory was confirmed; the most frequent prey items (in over 40% of stomachs) were copepods, malacostracan larvae and fish larvae. In the

  8. Effects of wave-induced forcing on a circulation model of the North Sea

    Science.gov (United States)

    Staneva, Joanna; Alari, Victor; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian

    2017-04-01

    The effect of wind waves on water level and currents during two storms in the North Sea is investigated using a high-resolution NEMO model forced with fluxes and fields from a high-resolution wave model. The additional terms accounting for wave-current interaction that are considered in this study are the Stokes-Coriolis force and the sea-state dependent energy and momentum fluxes. The individual and collective role of these processes is quantified and the results are compared with a control run without wave effects as well as against current and water level measurements from coastal stations. We find a better agreement with observations when the circulation model is forced by sea-state dependent fluxes, especially in extreme events. The two extreme events, the storm Christian (25-27 October 2013), and about a month later, the storm Xaver (5-7 December 2013), induce different wave and surge conditions over the North Sea. Including the wave effects in the circulation model for the storm Xaver raises the modelled surge by more than 40 cm compared with the control run in the German Bight area. For the storm Christian, a difference of 20-30 cm in the surge level between the wave-forced and the stand-alone ocean model is found over the whole southern part of the North Sea. Moreover, the modelled vertical velocity profile fits the observations very well when the wave forcing is accounted for. The contribution of wave-induced forcing has been quantified indicating that this represents an important mechanism for improving water level and current predictions.

  9. Analysis of North Sea Offshore Wind Power Variability

    Directory of Open Access Journals (Sweden)

    Aymeric Buatois

    2014-05-01

    Full Text Available This paper evaluates, for a 2030 scenario, the impact on onshore power systems in terms of the variability of the power generated by 81 GW of offshore wind farms installed in the North Sea. Meso-scale reanalysis data are used as input for computing the hourly power production for offshore wind farms, and this total production is analyzed to identify the largest aggregated hourly power variations. Based on publicly available information, a simplified representation of the coastal power grid is built for the countries bordering the North Sea. Wind farms less than 60 km from shore are connected radially to the mainland, while the rest are connected to a hypothetical offshore HVDC (High-Voltage Direct Current power grid, designed such that wind curtailment does not exceed 1% of production. Loads and conventional power plants by technology and associated cost curves are computed for the various national power systems, based on 2030 projections. Using the MATLAB-based MATPOWER toolbox, the hourly optimal power flow for this regional hybrid AC/DC grid is computed for high, low and medium years from the meso-scale database. The largest net load variations are evaluated per market area and related to the extra load-following reserves that may be needed from conventional generators.

  10. Critical report of current fisheries management measures implemented for the North Sea mixed demersal fisheries

    DEFF Research Database (Denmark)

    Nielsen, J. Rasmus; Ulrich, Clara; Hegland, Troels J.

    the scientific advice, the development in recent years has been towards this gap being reduced. Management of the fisheries has undergone a number of structural and behavioral changes, and these have already yielded some positive results as the state of the demersal stocks in the North Sea have globally improved......, at least in the prosperous countries around the North Sea, provides only few jobs. Despite the above trends indicating positive effects of the most recent fisheries management of the North Sea mixed demersal fisheries there are a row of general problems in the present management. Population dynamics...... states’ ministers in the Council have exercised strong control over the fisheries management measures which have been developed and adopted on the background of proposals from the Commission and the Parliament, though since the ratification of the Lisbon Treaty the Parliament has assumed a role of co...

  11. Observed sea-level rise in the north Indian Ocean coasts during the past century

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    Content-Type text/plain; charset=UTF-8 91 Observed sea-level rise in the north Indian Ocean coasts during the past century A. S. Unnikrishnan National Institute of Oceanography, Dona Paula, Goa-403004 unni@nio.org Introduction Sea-level... rise is one of the good indicators of global warming. Rise in sea level occurs mainly through melting of glaciers, thermal expansion due to ocean warming and some other processes of relatively smaller magnitudes. Sea level rise is a global...

  12. Chemical and temperature profile data from CTD casts in the East China Sea, Sea of Japan, and North Pacific Ocean (NODC Accession 9700022)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical and temperature profile data were collected from CTD casts in the East China Sea, Sea of Japan, and North Pacific Ocean. Data were submitted by the Japan...

  13. Radar sounding of bedrock and water table at Chalk River

    International Nuclear Information System (INIS)

    Annan, A.P.; Davis, J.L.

    1979-01-01

    When a spill of radioactive waste occurs, one of the main concerns is the flow pattern of ground water in the area of the spill. Ground probing radar is a relatively new geophysical technique which can provide high resolution data on the surficial geology and water distribution. The results of some preliminary radar experiments conducted at Chalk River Nuclear Laboratories (CRNL) of the Atomic Energy of Canada Limited (AECL), Chalk River, Ontario are presented. (auth)

  14. Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice.

    Science.gov (United States)

    Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun

    2014-01-23

    In recent decades, Antarctica has experienced pronounced climate changes. The Antarctic Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not declined, but has instead undergone a perplexing redistribution. Antarctic climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed Antarctic Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic Ocean, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change.

  15. Gas deliveries from Haltenbanken/North Sea; Gassleveranser Haltenbanken/Nordsjoeen

    Energy Technology Data Exchange (ETDEWEB)

    Ramm, H.H.

    1995-12-31

    The conference paper relates to the development and delivery of natural gas from the Haltenbanken area and the North Sea on the Norwegian continental shelf. Alternatives of field developments and pipelines together with the allocation of contracts for securing the contractual delivery of natural gas to the European continent in future and an alternative delivery to the Scandinavian countries, are discussed. 2 figs.

  16. 150 years of ecosystem evolution in the North Sea - from pristine conditions to acidification

    Science.gov (United States)

    Pätsch, Johannes; Lorkowski, Ina; Kühn, Wilfried; Moll, Andreas; Serna, Alexandra

    2010-05-01

    The 3-d coupled physical-biogeochemical model ECOHAM was applied to the Northwest European Shelf (47° 41‘ - 63° 53' N, 15° 5' W - 13° 55' E) for the years 1860, 1960 and continuously for the time interval 1970 - 2006. From stable nitrogen isotope analysis in sediment cores of the German Bight in the southeastern part of the North Sea (inner shelf) we found the period before 1860 unaffected by anthropogenic river inputs of nitrogen. After this period the delta15N-ratios significantly increased from ~6 per mil to more than 8 per mil in recent sediments indicating eutrophication by anthropogenic nitrate mainly from intensive agriculture fertilization. We deduced from the successful simulation of delta15N patterns in recent sediments that during pristine conditions nitrogen loads of the main continental rivers were about 10% of the modern input while the deposition of inorganic atmospheric nitrogen was 28% of the recent atmospheric flux. The 1960-sediment exhibited similar delta15N-values as the recent sediment which allows the conclusion that eutrophication in the German Bight predates the 1960 period of rapidly increasing river loads. By comparing model results with observational data in the North Sea we analyzed the variability of simulated carbon fluxes (1970-2006) constituting the so called "shelf pump" which transports atmospheric CO2 via biological fixation, vertical export and advection into the adjacent North Atlantic. Even though the highly variable North Atlantic water-inflow which correlated with the North Atlantic Oscillation Index (NAOI) supplied the northern North Sea with strongly varying nutrient inputs, the interannual variability of the strength of the shelf pump was mainly governed by the variability of the southern basin's biological productivity. The net ecosystem production (NEP) in the southern North Sea varies around zero inducing CO2 exchange with the atmosphere which is near equilibrium. In the northern North Sea the strong positive

  17. Distribution patterns of wintering sea ducks in relation to the North Atlantic Oscillation and local environmental characteristics

    Science.gov (United States)

    Zipkin, Elise F.; Gardner, Beth; Gilbert, Andrew T.; O'Connell, Allan F.; Royle, J. Andrew; Silverman, Emily D.

    2010-01-01

    Twelve species of North American sea ducks (Tribe Mergini) winter off the eastern coast of the United States and Canada. Yet, despite their seasonal proximity to urbanized areas in this region, there is limited information on patterns of wintering sea duck habitat use. It is difficult to gather information on sea ducks because of the relative inaccessibility of their offshore locations, their high degree of mobility, and their aggregated distributions. To characterize environmental conditions that affect wintering distributions, as well as their geographic ranges, we analyzed count data on five species of sea ducks (black scoters Melanitta nigra americana, surf scoters M. perspicillata, white-winged scoters M. fusca, common eiders Somateria mollissima, and long-tailed ducks Clangula hyemalis) that were collected during the Atlantic Flyway Sea Duck Survey for ten years starting in the early 1990s. We modeled count data for each species within ten-nautical-mile linear survey segments using a zero-inflated negative binomial model that included four local-scale habitat covariates (sea surface temperature, mean bottom depth, maximum bottom slope, and a variable to indicate if the segment was in a bay or not), one broad-scale covariate (the North Atlantic Oscillation), and a temporal correlation component. Our results indicate that species distributions have strong latitudinal gradients and consistency in local habitat use. The North Atlantic Oscillation was the only environmental covariate that had a significant (but variable) effect on the expected count for all five species, suggesting that broad-scale climatic conditions may be directly or indirectly important to the distributions of wintering sea ducks. Our results provide critical information on species-habitat associations, elucidate the complicated relationship between the North Atlantic Oscillation, sea surface temperature, and local sea duck abundances, and should be useful in assessing the impacts of climate

  18. Stylolites, porosity, depositional texture, and silicates in chalk facies sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Borre, Mai K.

    2007-01-01

    dissolution around 490 m below sea floor (bsf) corresponds to an interval of waning porosity-decline, and even the occurrence of proper stylolites from 830 m bsf is accompanied by only minor porosity reduction. Because opal is present, the pore-water is relatively rich in Si which through the formation of Ca......-silica complexes causes an apparent super-saturation of Ca and retards cementation. The onset of massive pore-filling cementation at 1100 m bsf may be controlled by the temperature-dependent transition from opal-CT to quartz. In the stylolite-bearing chalk of two wells in the Gorm and Tyra fields, the nannofossil...... matrix shows recrystallization but only minor pore-filling cement, whereas microfossils are cemented. Cementation in Gorm and Tyra is thus partial and has apparently not been retarded by opal-controlled pore-water. A possible explanation is that, due to the relatively high temperature, silica has...

  19. Prevalence and molecular characterisation of Acanthocephala in pinnipedia of the North and Baltic Seas

    Directory of Open Access Journals (Sweden)

    Patrick Waindok

    2018-04-01

    Full Text Available Harbour seals (Phoca vitulina and grey seals (Halichoerus grypus are final hosts of acanthocephalans in the German North and Baltic Seas. Parasitic infections in seals can cause pathological changes, which may result in deteriorated health of the host. Common gastrointestinal parasites of harbour and grey seals are acanthocephalans and a number of 275 of 2460 (11.2% investigated seals from 1996 to 2013 were infected with Corynosoma spp. (Acanthocephala, Polymorphidae. The prevalence showed a wave-like pattern: it increased from 1.2% and 0.4% in 1996 and 1997, respectively, to 23.9% during the second phocine distemper epizootic in 2002 and decreased to 6.2% in 2004. In 2005, prevalence peaked again with 25.0% followed by a decrease to 9.3% in 2009 and an increase to 38.5% in 2012. Statistical analysis revealed that harbour seals originating from the North Sea showed a higher prevalence than grey seals, whereas no significant difference between grey and harbour seals from the Baltic Sea was observed. Furthermore, juvenile pinnipedia from the North Sea were significantly less infected with Corynosoma spp. than seals older than seven month. Molecular species identification as well as phylogenetic relationship analysis among the detected Corynosoma species were achieved by sequencing and comparisons of the ribosomal ITS1-5.8S-ITS2-complex and cytochrome-c-oxidase I gene. Molecular analysis resulted in a newly arranged distribution of Acanthocephala in the North Sea as in contrast to previous studies, C. strumosum could not be confirmed as predominant species. Instead, C. magdaleni and a C. magdaleni isolate (isolate Pv1NS with an atypical number of longitudinal rows of hooks at the proboscis were detected. Furthermore, morphological and molecular analyses indicate the possible finding of a cryptic species (Candidatus Corynosoma nortmeri sp. nov.. Keywords: Acanthocephala, Acantocephalans, Corynosoma, Seals, ITS, Cytochrome-c-oxidase, Marine parasites

  20. Historical marine ecology: examining the role of fisheries in changes in North Sea benthos.

    Science.gov (United States)

    Robinson, Leonie A; Frid, Chris L J

    2008-07-01

    The organisms living on and in the sea floor, the benthos, represent an important ecological group. Although some (shellfish) have an economic value, most do not, and so little long-term data are available. We have identified three sources of historic benthic data for the North Sea, a regional sea that has been subjected to multiple human impacts for at least several hundred years. Each dataset has its limitations, but by their use together some issues emerge. Wider community shifts were observed in the shorter term and a number of extirpations at the scale of the North Sea were seen over longer time scales. The extirpated taxa share a number of characteristics consistent with an effect of fisheries such as fragile morphology. We must concentrate now on furthering our understanding of the ecological significance of shifts in dominance of particular functional units and protecting those habitats and species most vulnerable to fisheries-driven extirpation.

  1. Improved Oil Recovery in Chalk. Spontaneous Imbibition affected by Wettability, Rock Framework and Interfacial Tension

    Energy Technology Data Exchange (ETDEWEB)

    Milter, J.

    1996-12-31

    The author of this doctoral thesis aims to improve the oil recovery from fractured chalk reservoirs, i.e., maximize the area of swept zones and their displacement efficiencies. In order to identify an improved oil recovery method in chalk, it is necessary to study wettability of calcium carbonate and spontaneous imbibition potential. The thesis contains an investigation of thin films and wettability of single calcite surfaces. The results of thin film experiments are used to evaluate spontaneous imbibition experiments in different chalk types. The chalk types were described detailed enough to permit considering the influence of texture, pore size and pore throat size distributions, pore geometry, and surface roughness on wettability and spontaneous imbibition. Finally, impacts of interfacial tension by adding anionic and cationic surfactants to the imbibing water phase are studied at different wettabilities of a well known chalk material. 232 refs., 97 figs., 13 tabs.

  2. Evaluation of harvest and information needs for North American sea ducks

    Science.gov (United States)

    Koneff, Mark D.; Zimmerman, Guthrie S.; Dwyer, Chris P.; Fleming, Kathleen K.; Padding, Paul I.; Devers, Patrick K.; Johnson, Fred A.; Runge, Michael C.; Roberts, Anthony J.

    2017-01-01

    Wildlife managers routinely seek to establish sustainable limits of sport harvest or other regulated forms of take while confronted with considerable uncertainty. A growing body of ecological research focuses on methods to describe and account for uncertainty in management decision-making and to prioritize research and monitoring investments to reduce the most influential uncertainties. We used simulation methods incorporating measures of demographic uncertainty to evaluate risk of overharvest and prioritize information needs for North American sea ducks (Tribe Mergini). Sea ducks are popular game birds in North America, yet they are poorly monitored and their population dynamics are poorly understood relative to other North American waterfowl. There have been few attempts to assess the sustainability of harvest of North American sea ducks, and no formal harvest strategy exists in the U.S. or Canada to guide management. The popularity of sea duck hunting, extended hunting opportunity for some populations (i.e., special seasons and/or bag limits), and population declines have led to concern about potential overharvest. We used Monte Carlo simulation to contrast estimates of allowable harvest and observed harvest and assess risk of overharvest for 7 populations of North American sea ducks: the American subspecies of common eider (Somateria mollissima dresseri), eastern and western populations of black scoter (Melanitta americana) and surf scoter (M. perspicillata), and continental populations of white-winged scoter (M. fusca) and long-tailed duck (Clangula hyemalis). We combined information from empirical studies and the opinions of experts through formal elicitation to create probability distributions reflecting uncertainty in the individual demographic parameters used in this assessment. Estimates of maximum growth (rmax), and therefore of allowable harvest, were highly uncertain for all populations. Long-tailed duck and American common eider appeared to be at high

  3. Variability and connectivity of plaice populations from the Eastern North Sea to the Western Baltic Sea, and implications for assessment and management

    DEFF Research Database (Denmark)

    Ulrich, Clara; Boje, Jesper; Cardinale, Massimiliano

    2013-01-01

    and management. Plaice in Kattegat and Skagerrak have traditionally been considered as one stock unit. Current understanding indicates that several plaice components may exist in the transition area between the North Sea and the Baltic Sea. A comprehensive review of all available biological knowledge on plaice...

  4. Diagenesis of silica-rich mounded chalk, the Coniacian Arnager Limestone, Denmark

    DEFF Research Database (Denmark)

    Buus Madsen, Heine; Stemmerik, Lars; Surlyk, Finn

    2010-01-01

    The Coniacian Arnager Limestone Formation is exposed on the Danish island of Bornholm in the Baltic Sea. It is composed of mound-bedded siliceous chalk, and X-ray diffraction and scanning electron microscopy indicate a content of 30-70% insoluble minerals, including authigenic opal-CT, quartz......, clinoptilolite, feldspars, calcite, dolomite, and barite. Opal-CT and clinoptilolite are the most common and constitute 16-53% and 2-9%, respectively. The content of insoluble minerals varies laterally bothwithinthemounds and inplanar beds, and the opal-CT content varies by up to 10% vertically. Themounds...... precipitation of opal-CT. The opal-CT formed at temperatures around 17°C, the precipitation lowered the silica activity and the Si/Al ratio of the pore water, resulting in precipitation of clinoptilolite, feldspar and smectite. Calcite formed synchronouslywith the latest clinoptilolite.Minoramounts of quartz...

  5. Assessment of undiscovered conventional oil and gas resources in the West Korea Bay–North Yellow Sea Basin, North Korea and China, 2017

    Science.gov (United States)

    Schenk, Christopher J.; Tennyson, Marilyn E.; Mercier, Tracey J.; Hawkins, Sarah J.; Finn, Thomas M.; Gaswirth, Stephanie B.; Marra, Kristen R.; Klett, Timothy R.; Le, Phuong A.; Leathers-Miller, Heidi M.; Woodall, Cheryl A.

    2017-07-11

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable conventional resources of 1.1 billion barrels of oil and 2.2 trillion cubic feet of gas in the West Korea Bay–North Yellow Sea Basin, North Korea and China.

  6. Variability and connectivity of plaice populations from the Eastern North Sea to the Baltic Sea, part II. Biological evidence of population mixing

    DEFF Research Database (Denmark)

    Ulrich, Clara; Hansen, Jakob Hemmer; Boje, Jesper

    2016-01-01

    in parallel. Genetic markers suggested the existence of different genetic populations in the transition area. Growth backcalculation with otoliths resulted in significant although limited differences in growth rates between North Sea and Skagerrak, indicating weak differentiation or important mixing......A multi-disciplinary study was conducted to clarify stock identity and connectivity patterns in the populations of European plaice (Pleuronectes platessa) in the Skagerrak-Kattegat transition area between the Eastern North Sea and the Baltic Sea. Five independent biological studies were carried out...... constitute a large share of the catches in this area. The mixing of different populations within a management area has implications for stock assessment and management. Choice must be made to either lump or split the populations, and the feasibility and constraints of both options are discussed. The outcomes...

  7. Shifts in North Sea forage fish productivity and potential fisheries yield

    NARCIS (Netherlands)

    Clausen, Lotte W.; Rindorf, Anna; Deurs, van Mikael; Dickey-Collas, Mark; Hintzen, Niels T.

    2018-01-01

    1. Forage fish populations support large scale fisheries and are key components of marine ecosystems across the world, linking secondary production to higher trophic levels. While climate-induced changes in the North Sea zooplankton community are described and documented in literature, the

  8. Reactive transport modelling of groundwater chemistry in a chalk aquifer at the watershed scale.

    Science.gov (United States)

    Mangeret, A; De Windt, L; Crançon, P

    2012-09-01

    This study investigates thermodynamics and kinetics of water-rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO(2) concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5×10(-5) mol(chalk)L (-1) water year (-1). Sensitivity analysis indicates that the CO(2) partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Quaternary evolution of the North Sea and the English Channel

    NARCIS (Netherlands)

    Gibbard, P.L.; Cohen, K.M.

    The island of Britain is surrounded by a ‘moat’ of water, of which the English Channel and the North Sea are two major components. This talk described some major events that occurred to shape these seaways and, in particular, the evidence preserved on the Channel seabed. Here a system of valleys

  10. PHYTOPLANKTON OF THE NORTH-SEA AND ITS DYNAMICS - A REVIEW

    NARCIS (Netherlands)

    REID, PC; LANCELOT, C; GIESKES, WWC; HAGMEIER, E; WEICHART, G

    Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m-2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of

  11. PHYTOPLANKTON OF THE NORTH-SEA AND ITS DYNAMICS - A REVIEW

    NARCIS (Netherlands)

    REID, PC; LANCELOT, C; GIESKES, WWC; HAGMEIER, E; WEICHART, G

    1990-01-01

    Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m-2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of

  12. Seamount physiography and biology in the north-east Atlantic and Mediterranean Sea

    OpenAIRE

    Morato, T.; Kvile, K. Ø.; Taranto, G. H.; Tempera, F.; Narayanaswamy, B. E.; Hebbeln, D.; Menezes, G. M.; Wienberg, C.; Santos, R. S.; Pitcher, T. J.

    2013-01-01

    This work aims at characterising the seamount physiography and biology in the OSPAR Convention limits (north-east Atlantic Ocean) and Mediterranean Sea. We first inferred potential abundance, location and morphological characteristics of seamounts, and secondly, summarized the existing biological, geological and oceanographic in situ research, identifying examples of well-studied seamounts. Our study showed that the seamount population in the OSPAR area (north-east Atlantic) and in the Medite...

  13. Exchanges between the open Black Sea and its North West shelf

    Science.gov (United States)

    Shapiro, Georgy; Wobus, Fred; Zhou, Feng

    2014-05-01

    Exchanges between the vast NW shelf and the deep basin of the Black Sea play a significant role in maintaining the balance of nutrients, heat content and salinity of the shelf waters. Nearly 87 % of the Black Sea is entirely anoxic below 70 to 200m and contains high levels of hydrogen sulphide (Zaitsev et al, 2001), and this makes the shelf waters particularly valuable for maintaining the Black Sea ecosystem in good health. The increase in salinity of shelf waters occurs partially due to exchanges with more saline open sea waters and represents a threat to relics and endemic species. The shelf-break is commonly considered the bottle-neck of the shelf-deep sea exchanges (e.g. (Huthnance, 1995, Ivanov et al, 1997). Due to conservation of potential vorticity, the geostrophic currents flow along the contours of constant depth. However the ageostrophic flows (Ekman drift, mesoscale eddies, filaments, internal waves) are not subject to the same constraints. It has been shown that during the winter well mixed cold waters formed on the North West shelf propagate into the deep sea, providing an important mechanism for the replenishment of the Cold Intermediate Layer ( Staneva and Stanev, 1997). However, much less is known about exchanges in the warm season. In this study, the transports of water, heat and salt between the northwestern shelf and the adjacent deep basin of the Black Sea are investigated using a high-resolution three-dimensional primitive equation model, NEMO-SHELF-BLS (Shapiro et al, 2013). It is shown that during the period from April to August, 2005, both onshore and offshore cross-shelf break transports in the top 20 m were as high as 0.24 Sv on average, which was equivalent to the replacement of 60% of the volume of surface shelf waters (0 - 20 m) per month. Two main exchange mechanisms are studied: (i) Ekman transport, and (ii) transport by mesoscale eddies and associated meanders of the Rim Current. The Ekman drift causes nearly uniform onshore or

  14. Recruitment decline in North Sea herring is accompanied by reduced larval growth rates

    DEFF Research Database (Denmark)

    Payne, Mark; Ross, Stine Dalmann; Worsøe Clausen, Lotte

    2013-01-01

    The stock of North Sea autumn spawning herring (Clupea harengus L.) has shown an unprecedented sequence of ten years of sharply reduced recruitment, in spite of a high spawning biomass. Recent work has identified this below-expected recruitment as being determined during the larval phase: however...... rate of 8%, concurrent with the reduced larval survival and recruitment, was identified: after correcting for the effect of other explanatory variables (e.g. temperature changes), the gross reduction was found to be 12%. This reduction is most probably due to changes in either the amount or quality...... and larvae survival, thereby narrowing the range of potential mechanisms underlying the observed reduction in the recruitment of North Sea autumn spawning herring...

  15. Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton.

    Directory of Open Access Journals (Sweden)

    Delphine Nicolas

    Full Text Available The North Sea cod (Gadus morhua, L. stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature and/or indirect (i.e. changes in the quantity and quality of zooplankton prey effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability.

  16. Petrophysical and rock-mechanics effects of CO2 injection for enhanced oil recovery

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, Morten Leth; Christensen, Helle Foged

    2014-01-01

    this issue we studied two types of chalk from South Arne field, North Sea: (1) Ekofisk Formation having >12% non-carbonate and (2) Tor Formation, which has less than 5% non-carbonate. We performed a series of laboratory experiments to reveal the changes in petrophysical and rock-mechanics properties due...... reservoirs. North Sea chalk is characterized by high porosity but also high specific surface causing low permeability. A high porosity provides room for CO2 storage, while a high specific surface causes a high risk for chemical reaction and consequently for mechanical weakening. In order to address...... to the injection of CO2 at supercritical state. We analyzed these changes with respect to the differences in porosity, specific surface, pore stiffness, wettability, mineralogy and mechanical strength. We observed a 2–3% increase in porosity, a minor decrease of specific surface and consequently a small increase...

  17. Reactor safety research and development in Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Nitheanandan, T. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    Atomic Energy of Canada Limited's Chalk River Laboratories provides three different services to stakeholders and customers. The first service provided by the laboratory is the implementation of Research and Development (R&D) programs to provide the underlying technological basis of safe nuclear power reactor designs. A significant portion of the Canadian R&D capability in reactor safety resides at Atomic Energy of Canada Limited's Chalk River Laboratories, and this capability was instrumental in providing the science and technology required to aid in the safety design of CANDU power reactors. The second role of the laboratory has been in supporting nuclear facility licensees to ensure the continued safe operation of nuclear facilities, and to develop safety cases to justify continued operation. The licensing of plant life extension is a key industry objective, requiring extensive research on degradation mechanisms, such that safety cases are based on the original safety design data and valid and realistic assumptions regarding the effect of ageing and management of plant life. Recently, Chalk River Laboratories has been engaged in a third role in research to provide the technical basis and improved understanding for decision making by regulatory bodies. The state-of-the-art test facilities in Chalk River Laboratories have been contributing to the R&D needs of all three roles, not only in Canada but also in the international community, thorough Canada's participation in cooperative programs lead by International Atomic Energy Agency and the OECD's Nuclear Energy Agency. (author)

  18. Province of Ontario nuclear emergency plan part V - Chalk River

    International Nuclear Information System (INIS)

    1991-10-01

    The aim of Part 5 of the Provincial Nuclear Emergency Plan is to describe the measures that shall be undertaken to deal with a nuclear emergency caused by the Chalk River Laboratories. This plan deals mainly with actions at the Provincial level and shall by supplemented by the appropriate Municipal Plan. The Townships of Rolph, Buchanan, Wylie, and McKay, the Town of Deep River and the Village of Chalk River are the designated municipalities with respect to CRL. 2 tabs., 5 figs

  19. Province of Ontario nuclear emergency plan part V - Chalk River

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-10-01

    The aim of Part 5 of the Provincial Nuclear Emergency Plan is to describe the measures that shall be undertaken to deal with a nuclear emergency caused by the Chalk River Laboratories. This plan deals mainly with actions at the Provincial level and shall by supplemented by the appropriate Municipal Plan. The Townships of Rolph, Buchanan, Wylie, and McKay, the Town of Deep River and the Village of Chalk River are the designated municipalities with respect to CRL. 2 tabs., 5 figs.

  20. Estimation of new production in the North Sea: consequences for temporal and spatial variability of phytoplankton

    DEFF Research Database (Denmark)

    Richardson, Katherine; Bo Pedersen, Flemming

    1998-01-01

    By coupling knowledge of oceanographic processes and phytoplankton responses to light and nutrient availability, we estimate a total potential new (sensu Dugdale and Goering,1967) production for the North Sea of approximately 15.6 million tons C per year. In a typical year, about 40......% of this production will be associated with the spring bloom in the surface waters of the seasonally stratified (central and northern) North Sea. About 40% is predicted to occur in the coastal waters while the remaining new production is predicted to take place in sub-surface chlorophyll peaks occuring in association...... with fronts in the North Sea during summer month. By considering the inter-annual variation in heat, wind and nutrient availability (light and tidal energy input are treated as non-varying from year to year), the inter-annual variability in the new production occuring in these different regions is estimated...

  1. Biot Critical Frequency Applied to Description of Failure and Yield of Highly Porous Chalk with Different Pore Fluids

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    Injection of water into chalk hydrocarbon reservoirs has led to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. In case of water-saturated samples, the concentration...... is controlled by solid-fluid friction. The reference frequency is thus a measure of this friction, and we propose that the fluid effect on mechanical properties of chalk may be the result of liquid-solid friction. We reviewed 622 published experiments on mechanical properties of porous chalk. The data include...... chalk samples that were tested at temperatures from 20 °C to 130 °C with the following pore fluids: fresh water, synthetic seawater, glycol, and oil of varying viscosity. The critical frequency is calculated for each experiment. For each specimen, we calculate the thickness to the slipping plane outside...

  2. Temporal and spatial variability of nutrients and oxygen in the North Aegean Sea during the last thirty years

    Directory of Open Access Journals (Sweden)

    Ε. SOUVERMEZOGLOU

    2014-12-01

    Full Text Available Inorganic nutrient and dissolved oxygen data collected in the North Aegean Sea during 1986 - 2008 were analyzed in order to evaluate the role of the inflowing Black Sea originated surface water (BSW in the nutrient regime of the area.  In periods of high buoyancy inflow from Dardanelles strait, a reduction of inorganic nutrients in the surface layer is observed along the north-west route of the BSW; in parallel, the underlying layer of Levantine intermediate water revealed an increase of inorganic nutrients, receiving the degradation material from the surface layer. The above spatial patterns suggest a contribution of the BSW to the observed enhanced production of the North Aegean Sea. Anomalously low buoyancy inflow of BSW combined with severe winter meteorological conditions promote deep water formation events. The physical and chemical characteristics of the deep waters found in the different basins of the North Aegean Sea in 1997 (following the deep water formation in winters of 1992-1993 differed from those observed after the formation in winter 1987. These differences were probably related to the drastic changes occurred in the deep waters of the Eastern Mediterranean in the early 1990, by the Eastern Mediterranean Transient. Considering that deep water formation processes provide occasionally inorganic nutrients to the euphotic layer, it seems that BSW through its uninterrupted supply of small quantities of nutrients should play an additional role in the production in the North Aegean Sea.

  3. THE STUDY OF TECHNOLOGICAL PROPERTIES OF PLASTISOLS BASED EMULSION PVC FILLED WITH CHALK GIDROFOBIZIROVANNYM

    Directory of Open Access Journals (Sweden)

    V. A. Sedykh

    2014-01-01

    Full Text Available Baby toys are made using the centrifugal molding plastisol based emulsion of polyvinyl chloride plasticized with dioctylphthalate. To reduce cost and decrease biotelemetry the dioctylphthalate on the surface of the product domestic toys than toys produced in China, there was a necessity of introduction of the filler is chalk from different manufacturers. By using a Brookfield vis-cometer PV-D was studied rheology of filled hydrophobized chalk PVC plastisols in storage conditions for up to 72 hours at temperatures of 14-20°C. It was found that the flow plastisols consistent with pseudo-plastic fluids. Given the flow rates of emulsion PVC plastisols filled to 35 % of the mass. hydrophobized chalk. The influence of the content of the plasticizer dioctylphthalate in a narrow interval (37,0 - 41,4 % of the mass. on the viscosity of polymer pastes and the kinetics of its changes during storage. Revealed a linear dependence of the viscosity of the filled hydrophobized chalk plastisols on the speed of rotation of the spindle of the viscometer and during storage. Given the rate of expansion changes the viscosity of the plastisols of the speed of rotation of the spindle of the viscometer, the rate of change in viscosity and calculation of the initial viscosity. Determined the stability of the dispersion hydrophobized chalk in a colloidal solution of PVC in dioctylphthalate during storage. We determined the variation of the content of chalk (ash with top and bottom layers plastisols height 8 cm after 24 hours storage. It is proved that the temperature of the preparation and storage of polymer pastes were determining factors in the regulation of such technological properties of PVC plastisols in the presence hydrophobized chalkas viscosity, stability of the dispersion of chalk and, consequently, the efficiency of distribution plastisols in the form of a centrifugal molding.

  4. Role of North Indian Ocean Air-Sea Interaction in Summer Monsoon Intraseasonal Oscillation

    Science.gov (United States)

    Zhang, L.; Han, W.; Li, Y.

    2017-12-01

    Air-sea coupling processes over the North Indian Ocean associated with Indian summer monsoon intraseasonal oscillation (MISO) are analyzed. Observations show that MISO convection anomalies affect underlying sea surface temperature (SST) through changes in surface shortwave radiation (via cloud cover change) and surface latent heat flux (associated with surface wind speed change). In turn, SST anomalies determine the changing rate of MISO precipitation (dP/dt): warm (cold) SST anomalies cause increasing (decreasing) precipitation rate through increasing (decreasing) surface convergence. Air-sea interaction gives rise to a quadrature relationship between MISO precipitation and SST anomalies. A local air-sea coupling model (LACM) is established based on these observed physical processes, which is a damped oscillatory system with no external forcing. The period of LACM is proportional to the square root of mean state mixed layer depth , assuming other physical parameters remain unchanged. Hence, LACM predicts a relatively short (long) MISO period over the North Indian Ocean during the May-June monsoon developing (July-August mature) phase when is shallow (deep). This result is consistent with observed MISO statistics. An oscillatory external forcing of a typical 30-day period is added to LACM, representing intraseasonal oscillations originated from the equatorial Indian Ocean and propagate into the North Indian Ocean. The period of LACM is then determined by both the inherent period associated with local air-sea coupling and the period of external forcing. It is found that resonance occurs when , amplifying the MISO in situ. This result explains the larger MISO amplitude during the monsoon developing phase compared to the mature phase, which is associated with seasonal cycle of . LACM, however, fails to predict the observed small MISO amplitude during the September-October monsoon decaying phase, when is also shallow. This deficiency might be associated with the

  5. Fulmar Litter EcoQO monitoring along Durch and North Sea coasts

    NARCIS (Netherlands)

    Franeker, van J.A.

    2011-01-01

    Wastes from ships are an important source of litter in the marine environment in the Southern North Sea and cause serious economic and ecological damage. Inadequacies in the ship to shore waste delivery procedures are considered a major factor in illegal discharges. The European Union addressed the

  6. The paleocene in north Africa - Sea-level changes and paleoproductivity in Tunisa, Libya and Egypt using microfossils

    NARCIS (Netherlands)

    Guasti, E.; Lüning, S.

    2009-01-01

    The Paleocene is a time of warm oceans and generally high sea levels. In North Africa, vast epicontinental seas extended far inside the African continent. In this paper we correlate sea level, primary paleoproductivity and facies distribution of the proximal, carbonate-dominated Paleocene deposits

  7. Finance and North Sea oil: the challenge of non-recourse finance

    Energy Technology Data Exchange (ETDEWEB)

    White, N A

    1976-04-01

    Many companies operating in the North Sea feel that the financial community is not responding to the complexity of their situation brought about by the interplay between national legislation and fiscal measures, technological development, extreme weather conditions, OPEC decisions, or falling oil demand. The financial community feels it is lending its depositors' money and the kind of innovations required by some companies in the oil industry would reduce its level of security. After reviewing the possible solutions, the author concludes that it is highly unlikely that non-resource finance in large amounts will be available without collateral, or other security, from outside the North Sea area. The author offers his suggestion and preference for a new kind of vehicle to be designed by the financial institutions that would provide the necessary guarantees to the lending consortium in accordance with the needs of the individual participant in the license or field project. (MCW)

  8. Coastal Sea Level along the North Eastern Atlantic Shelf from Delay Doppler Altimetry

    Science.gov (United States)

    Fenoglio-Marc, L.; Benveniste, J.; Andersen, O. B.; Gravelle, M.; Dinardo, S.; Uebbing, B.; Scharroo, R.; Kusche, J.; Kern, M.; Buchhaupt, C.

    2017-12-01

    Satellite altimetry data of the CryoSat-2 and Sentinel-3 missions processed with Delay Doppler methodology (DDA) provide improved coastal sea level measurements up to 2-4 km from coast, thanks to an along-track resolution of about 300m and a higher signal to noise ratio. We investigate the 10 Kilometre stripe along the North-Eastern Atlantic shelf from Lisbon to Bergen to detect the possible impacts in sea level change studies of this enhanced dataset. We consider SAR CryoSat-2 and Sentinel-3 altimetry products from the ESA GPOD processor and in-house reduced SAR altimetry (RDSAR) products. Improved processing includes in RDSAR the application of enhanced retrackers for the RDSAR waveform. Improved processing in SAR includes modification both in the generation of SAR waveforms, (as Hamming weighting window on the burst data prior to the azimuth FFT, zero-padding prior to the range FFT, doubling of the extension for the radar range swath) and in the SAMOSA2 retracker. Data cover the full lifetime of CryoSat-2 (6 years) and Sentinel-3 (1 year). Conventional altimetry are from the sea level CCI database. First we analyse the impact of these SAR altimeter data on the sea level trend and on the estimation of vertical motion from the altimeter minus tide gauge differences. VLM along the North-Eastern Atlantic shelf is generally small compared to the North-Western Atlantic Coast VLM, with a smaller signal to noise ratio. Second we investigate impact on the coastal mean sea level surface and the mean dynamic topography. We evaluate a mean surface from the new altimeter data to be combined to state of the art geoid models to derive the mean dynamic topography. We compare the results to existing oceanographic and geodetic mean dynamic topography solutions, both on grid and pointwise at the tide gauge stations. This study is supported by ESA through the Sea Level CCI and the GOCE++DYCOT projects

  9. Organophosphorus flame retardants and plasticizers in the atmosphere of the North Sea

    International Nuclear Information System (INIS)

    Moeller, Axel; Xie Zhiyong; Caba, Armando; Sturm, Renate; Ebinghaus, Ralf

    2011-01-01

    Air samples collected in the German part of the North Sea from March to July 2010 were investigated for organophosphorus compounds (OPs) being applied as flame retardants and plasticizers. The Σ 8 OPs concentration ranged from 110 to 1400 pg m -3 while tris(2-chloroisopropyl) phosphate (TCPP) dominated all samples with individual concentrations up to 1200 pg m -3 . The highest concentrations were observed in continental air masses showing the high influence of industrialized regions including production sites on atmospheric emissions and concentrations. The occurrence of OPs even in oceanic/Arctic air masses shows that OPs can undergo long-range atmospheric transport. Dry particle-bound deposition fluxes from 9 to 240 ng m -2 d -1 for Σ 8 OPs were estimated leading to a minimum annual flux of 710 ± 580 kg y -1 OPs into the German North Sea. This study presents the first occurrence of OPs in the marine atmosphere together with important information on their long-range transport potential. - Highlights: → Organophosphorus flame retardants are detected for the first time in the marine atmosphere. → Organophosphorus compounds can undergo medium to long-range atmospheric transport. → Western Europe emits organophosphorus compounds to the marine atmosphere. → Marine air levels of organophosphorus flame retardants range up to 1 ng/m 3 . - Organophosphorus flame retardants, in particular tris(2-chloroisopropyl) phosphate, are emitted into the North Sea atmosphere by Western European countries.

  10. North-American MP Tandem accelerators

    International Nuclear Information System (INIS)

    Wegner, H.E.; Thieberger, P.

    1977-01-01

    There are six North-American MP Tandem accelerators: Yale; Minnesota; Chalk River; Rochester; and two at Brookhaven. The current status and operating characteristics of these six tandem accelerators are discussed. Upgrade and special improvements of the different machines is reviewed and new developments since the last Electrostatic Conference are discussed in detail. The overall operating characteristics of the different machines during the last year of operation are compared

  11. Closing the Gaps in Offshore P&A: Lessons Learned From the North Sea

    Science.gov (United States)

    Torsater, M.

    2017-12-01

    This talk will give an overview of the major challenges related to offshore well plugging and abandonment (P&A) with examples from the North Sea. The talk will outline why today's P&A operations are so time consuming and expensive, and it will point out current technology gaps and issues related to standards and regulations in the North Sea countries. Emerging P&A solutions will be discussed, and results from large ongoing research projects in Norway will be shared. Special emphasis will be given to promising new concepts, such as using creeping shale formations as permanent well barriers, and using thermal methods for removal of tubing and casing. The long-term aspects of well plugging will also be discussed, together with methods available for minimizing leakage risk.

  12. The new players - what's happening?[Talisman's petroleum activity in the North Sea]; De nye aktoerene - hva skjer?

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, Baard

    2005-03-15

    The oil company Talisman Energy and its activities in the North Sea are presented. The global corporation's strategy is briefly outlined, and this includes focus on upstream activities, area and product mix, having operator responsibility and exploration activities. North America and the North Sea represent 69 percent of the company's reserves and 76 percent of the production. the North Sea challenges for the future are among others the Norwegian fiscal system which does not stimulate marginal activities, leading to a lower level of activity, less focus on cost, premature removal of offshore infrastructure and fewer discoveries of new reserves (ml)

  13. Shallow Gas Migration along Hydrocarbon Wells-An Unconsidered, Anthropogenic Source of Biogenic Methane in the North Sea.

    Science.gov (United States)

    Vielstädte, Lisa; Haeckel, Matthias; Karstens, Jens; Linke, Peter; Schmidt, Mark; Steinle, Lea; Wallmann, Klaus

    2017-09-05

    Shallow gas migration along hydrocarbon wells constitutes a potential methane emission pathway that currently is not recognized in any regulatory framework or greenhouse gas inventory. Recently, the first methane emission measurements at three abandoned offshore wells in the Central North Sea (CNS) were conducted showing that considerable amounts of biogenic methane originating from shallow gas accumulations in the overburden of deep reservoirs were released by the boreholes. Here, we identify numerous wells poking through shallow gas pockets in 3-D seismic data of the CNS indicating that about one-third of the wells may leak, potentially releasing a total of 3-17 kt of methane per year into the North Sea. This poses a significant contribution to the North Sea methane budget. A large fraction of this gas (∼42%) may reach the atmosphere via direct bubble transport (0-2 kt yr -1 ) and via diffusive exchange of methane dissolving in the surface mixed layer (1-5 kt yr -1 ), as indicated by numerical modeling. In the North Sea and in other hydrocarbon-prolific provinces of the world shallow gas pockets are frequently observed in the sedimentary overburden and aggregate leakages along the numerous wells drilled in those areas may be significant.

  14. Post-Glacial Development of Western North Atlantic - Labrador Sea Oceanographic Circulation

    DEFF Research Database (Denmark)

    Sheldon, Christina

    2015-01-01

    The subpolar North Atlantic Ocean – Labrador Sea region is an important site for both oceanographic and atmospheric circulation. The convergence of ocean currents causes downwelling of cold, saline water in the subpolar gyre, helping to drive the world-wide thermohaline circulation system. The main......, the subpolar gyre weakened, which carried less Gulf Stream-derived water to the western North Atlantic Ocean via the West Greenland Current and the Slopewater Current, south of Newfoundland. Changes in the subpolar gyre circulation had developed to be analogous to the modern climate by approximately 2 cal kyr...... surface currents involved in the gyre are the south-flowing, cold and relatively fresh Labrador Current and the north-flowing, warm and relatively saline Gulf Stream. The oceanic front between these two major currents moves north and south, dependent on the relative strengths of the currents, impacting...

  15. Occurrence of Ergasilus megaceros Wilson, 1916, in the sea lamprey and other fishes from North America

    Science.gov (United States)

    Muzzall, Patrick M.; Hudson, Patrick L.

    2004-01-01

    Ergasilus megaceros (Copepoda: Ergasilidae) was recovered from the nasal fossae (lamellae) of the olfactory sac in 1 (1.8%) of 56 sea lampreys, Petromyzon marinus Linne, 1758, collected in May 2002 from the Cheboygan River, Michigan. Although the sea lamprey is a new host record for E. megaceros, this fish species may not be a preferred host because of its low prevalence. Ergasilus megaceros is the second ergasilid species reported from the sea lamprey in North America. This is the third report of an ergasilid species infecting the nasal fossae of fishes in North America, with E. rhinos being the only other species reported from this site.

  16. Description of the North Sea wind climate for wind energy applications

    NARCIS (Netherlands)

    Coelingh, J.P.; Wijk, A.J.M. van; Cleijne, J.W.; Pleune, R.

    1992-01-01

    In The Netherlands it is foreseen that wind turbines will be installed on offshore locations in the North Sea before the year 2010. Therefore adequate knowledge of the offshore wind climate should be obtained, both for the estimation of energy yields and for the determination of wind load

  17. Aerosol properties over the Arabian Sea during the north east monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Dulac, F; Leon, G.F; Desa, E.

    440, 670, 870, 936, 940 and 1020 mm, in the Arabian Sea between 15.4-17.86 degrees N and 73.28-69.3 degrees E, during the North East monsoon period of 1-10 December, 1998. The aerosol optical properties derived from these data showed variations from...

  18. Quantification of seep-related methane gas emissions at Tommeliten, North Sea

    NARCIS (Netherlands)

    Schneider von Deimling, J.S.; Rehder, G.; Greinert, J.; McGinnnis, D.F.; Boetius, A.; Linke, P.

    2011-01-01

    Tommeliten is a prominent methane seep area in the Central North Sea. Previous surveys revealed shallow gas-bearing sediments and methane gas ebullition into the water column. In this study, the in situ methane flux at Tommeliten is re-assessed and the potential methane transport to the atmosphere

  19. Combining sea state and land subsidence rates in an assessment of flooding hazards at the Danish North Sea coast

    DEFF Research Database (Denmark)

    Sørensen, Carlo Sass; Broge, Niels; Knudsen, Per

    Sand nourishments (2-3 M3/y) counteract erosion on the central North Sea coast of Denmark and dikes and artificial dunes protect the low-lying hinterland from flooding. The fisheries towns of Thyboron, Thorsminde and Hvide Sande are all liable to flooding during storm surges. Tide gauge series fr...... the coast are presented and the town of Thyboron is used as a case where, in addition to SLR and extremes, analyses of land movement and ocean-groundwater interactions are included in an integrated method for assessing future coastal flooding hazards.......Sand nourishments (2-3 M3/y) counteract erosion on the central North Sea coast of Denmark and dikes and artificial dunes protect the low-lying hinterland from flooding. The fisheries towns of Thyboron, Thorsminde and Hvide Sande are all liable to flooding during storm surges. Tide gauge series from...

  20. Nutrients, chlorophyll, fractional primary productivity in water column of the North Arabian Sea in support of the North Arabian Sea Environment and Ecosystem Research from 1992-1994 (NODC Accession 0000778)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Five cruises were carried out under the Pak-US cooperative project 'North Arabian Sea Environment and Ecosystem Research' (NASEER) from 1992-1994. The main objective...

  1. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from G.O. SARS in the North Greenland Sea, North Sea and Norwegian Sea from 2011-04-29 to 2011-11-01 (NCEI Accession 0157278)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157278 includes Surface underway, chemical, meteorological and physical data collected from G.O. SARS in the North Greenland Sea, North Sea and...

  2. Effort allocation of the Dutch beam trawl fleet in response to a temporarily closed area in the North Sea

    NARCIS (Netherlands)

    Rijnsdorp, A.D.; Piet, G.J.; Poos, J.J.

    2001-01-01

    The spawning stock of North Sea cod is at a historic low level and immediate management measures are needed to improve this situation. As a first step, the European Commission in 2001 closed a large area in the North Sea between February 15 and April 30 to all cod related fishing fleets in order to

  3. North Sea trends typify industry's worldwide adjustment to change

    International Nuclear Information System (INIS)

    Nicandros, C.S.

    1993-01-01

    In response to rapid industry changes, oil companies are employing new practices and entering new relationships. In the U.K. North Sea's Britannia field, Conoco (U.K.) Ltd. and Chevron (U.K.) Ltd. share duties of field operator in the region's first such business arrangement. Here, the Neddrill 6 semisubmersible drills a Britannia appraisal well. This report tells how companies are using teamwork and other techniques to derive maximum value from their assets and technologies

  4. The development of radioactive contamination of the North Sea fish and in the lower course of the rivers Elbe and Weser

    International Nuclear Information System (INIS)

    Feldt, W.; Kanisch, G.

    1985-01-01

    The discharge of radioactive waste water from radwaste treatment plants in England and in France has led to an increase in contamination of North Sea fish. In 1982, following water measurements, fish were caught in many places in the North Sea. The comparison similar measurements carried out in 1965 proves that in 1982 the contamination of North Sea fish with Cs-137 had increased by a factor of about 3. Subsequent developments of contamination of several kind of fish until 1984 are shown and the radiation exposure of the population from eating shrimps, mussels and fish is estimated. The radionuclides Cs-137, Ru-106 and Co-60 can be used to show to what extent the lower course of the rivers Elbe and Weser are affected by North Sea contamination, in particular by discharges from La Hague. (orig./HP) [de

  5. Contrasting trends in North Atlantic deep-water formation in the Labrador Sea and Nordic Seas during the Holocene

    NARCIS (Netherlands)

    Renssen, H.; Goosse, H.; Fichefet, T.

    2005-01-01

    The Holocene North Atlantic deep-water formation is studied in a 9,000-year long simulation with a coupled climate model of intermediate complexity, forced by changes in orbital forcing and atmospheric trace gas concentrations. During the experiment, deep-water formation in the Nordic Seas is

  6. Improving the assessment and management of the plaice stock complex between the North Sea and the Baltic Sea

    DEFF Research Database (Denmark)

    Ulrich, Clara; Boje, Jesper; Cardinale, Massimiliano

    2012-01-01

    Plaice in Kattegat and Skagerrak have traditionally been considered as one stock unit. However the collected information on biology and fishery in areas between the North and Baltic Seas suggest changes are needed in assessment units as well as in management areas. Plaice in Skagerrak (Division 20...

  7. Covariance among North Sea nutrient and climate drivers: consequences for plankton dynamics.

    NARCIS (Netherlands)

    McQuatters-Gollop, A.; Vermaat, J.E.

    2011-01-01

    Regime shift and principal component analysis of a spatially disaggregated database capturing time-series of climatic, nutrient and plankton variables in the North Sea revealed considerable covariance between groups of ecosystem indicators. Plankton and climate time-series span the period 1958-2003,

  8. From ooze to sedimentary rock, the first diagenetic processes affecting the chalk of eastern Denmark

    DEFF Research Database (Denmark)

    Moreau, Julien; Boussaha, Myriam; Nielsen, Lars

    processes operating in the chalk sediments at widely different scales into a single diagenetic model: At Stevns the chalk is affected by an extensive polygonal fault system which is expressed in onshore and offshore seismic profiles. Smaller scale contractional features like deformation bands (hairline...... strongly affect reservoir properties of the chalk both by establishing compartments and vertical connections. A better understanding of these reservoir modifications will be critical for improving the predictive capability of models describing the behaviour of drinking water and hydrocarbons hosted...

  9. Islands of steel rise over North Sea gas. Pt. 1

    Energy Technology Data Exchange (ETDEWEB)

    Hind, J A

    1965-10-27

    Nowhere is the offshore oil and gas prospecting boom more enthusiastic, urgent, and crowded than in the North Sea. The type of rig required for this type of offshore drilling mainly depends upon how far offshore drilling is to take place. The fixed jack-up type is most suitable where depth of water is not excessive and for actual drilling operations were the drill is most easily held steady over the hole. This type of rig presents a stability problem under tow from location to location with a shallow depth of hull. Depth of water limits the operational mobility of the submerged-type rig and it is the most prone to scouring effects. Fully floating and ship-mounted rigs solve the depth of water problem and many others associated with ocean transportation. However, this is at the expense of more difficult drilling operations and complexity of equipment. Semi-submersibles are a popular compromise between fixed sit-on-bottom rigs and fully floating types. From a naval architectural point of view they have much to recommend them as all- round units. Typical North Sea drill rigs are described and a table is given for complete details.

  10. Towards uncertainty estimation for operational forecast products - a multi-model-ensemble approach for the North Sea and the Baltic Sea

    Science.gov (United States)

    Golbeck, Inga; Li, Xin; Janssen, Frank

    2014-05-01

    Several independent operational ocean models provide forecasts of the ocean state (e.g. sea level, temperature, salinity and ice cover) in the North Sea and the Baltic Sea on a daily basis. These forecasts are the primary source of information for a variety of information and emergency response systems used e.g. to issue sea level warnings or carry out oil drift forecast. The forecasts are of course highly valuable as such, but often suffer from a lack of information on their uncertainty. With the aim of augmenting the existing operational ocean forecasts in the North Sea and the Baltic Sea by a measure of uncertainty a multi-model-ensemble (MME) system for sea surface temperature (SST), sea surface salinity (SSS) and water transports has been set up in the framework of the MyOcean-2 project. Members of MyOcean-2, the NOOS² and HIROMB/BOOS³ communities provide 48h-forecasts serving as inputs. Different variables are processed separately due to their different physical characteristics. Based on the so far collected daily MME products of SST and SSS, a statistical method, Empirical Orthogonal Function (EOF) analysis is applied to assess their spatial and temporal variability. For sea surface currents, progressive vector diagrams at specific points are consulted to estimate the performance of the circulation models especially in hydrodynamic important areas, e.g. inflow/outflow of the Baltic Sea, Norwegian trench and English Channel. For further versions of the MME system, it is planned to extend the MME to other variables like e.g. sea level, ocean currents or ice cover based on the needs of the model providers and their customers. It is also planned to include in-situ data to augment the uncertainty information and for validation purposes. Additionally, weighting methods will be implemented into the MME system to develop more complex uncertainty measures. The methodology used to create the MME will be outlined and different ensemble products will be presented. In

  11. Caoxite-hydroxyapatite composition as consolidating material for the chalk stone from Basarabi-Murfatlar churches ensemble

    Science.gov (United States)

    Ion, Rodica-Mariana; Turcanu-Caruţiu, Daniela; Fierăscu, Radu-Claudiu; Fierăscu, Irina; Bunghez, Ioana-Raluca; Ion, Mihaela-Lucia; Teodorescu, Sofia; Vasilievici, Gabriel; Rădiţoiu, Valentin

    2015-12-01

    The development of new composition for surface conservation of some architectural monuments represents now an important research topic. The Basarabi-Murfatlar Ensemble, recognized as the first religious monument from mediaeval Dobrogea (Romania) (from 9th to 11th century), is one of the most impressive archaeological sites of Europe. This ensemble is built from amorphous calcium carbonate, very sensitive to humidity, frost, salts, etc. The aim of this paper is to test on chalk stone samples a new consolidant - hydroxyapatite (HAp) mixed with calcium oxalate trihydrate (caoxite) (COT). Some specific techniques for evaluation its impact on chalk stone surface are used, as follows: petrographical and physical-chemical techniques: SEM, OM, ICP-AES, TGA, FTIR and Raman spectroscopy, chromatic parameters changes, the accelerated weathering tests: heating, freeze-thaw, and their effects on porosity and capillary water uptake by the chalk surface. All these have been evaluated before and after treatment with COT-HAp, putting into evidence the effect of the new composition on the chalk stone surface. HAp induces COT stabilization, and their joint composition can bind weathered stone blocks providing a substantial reinforcement of chalk surface.

  12. Transport process of Pu isotope in marginal seas of the western North Pacific Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Masatoshi [Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki, 036-8564, Aomori (Japan); Zheng, Jian [Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, 263-8555, Chiba (Japan)

    2014-07-01

    Significant quantities of Pu isotopes have been released into the marine environment as the result of atmospheric nuclear weapons testing. Most radionuclides globally dispersed in atmospheric nuclear weapons testing were released into the environment during the 1950's and 1960's. In the western North Pacific Ocean, the principal source can be further distinguished as two distinct sources of Pu: close-in tropospheric fallout from nuclear weapons testing at the Pacific Proving Grounds (PPG) in the Marshall Islands and global stratospheric fallout. Since the {sup 240}Pu/{sup 239}Pu atom ratio is characteristic for the Pu emission source, information on Pu isotopic signature is very useful to better understand the transport process in the oceans and to identify the sources of Pu. The mean atom ratio of {sup 240}Pu/{sup 239}Pu from the global stratospheric fallout is 0.180 ±0.014 based on soil sample data, whereas that from close-in tropospheric fallout from the PPG is 0.33 - 0.36. The {sup 240}Pu/{sup 239}Pu atom ratios in seawater samples collected in marginal seas of the western North Pacific Ocean will provide important and useful data for understanding the process controlling Pu transport and for distinguishing future Pu sources. The objectives of this study were to measure the {sup 239+240}Pu concentrations and {sup 240}Pu/{sup 239}Pu atom ratios in seawater from the Sea of Okhotsk, Japan Sea, South China Sea and Sulu Sea and to discuss the transport process of Pu. Large-volume seawater samples (250 L each) were collected from the surface to the bottom in marginal seas of the western North Pacific Ocean with acoustically triggered quadruple PVC sampling bottles during the R/V Hakuho-Maru cruise. The {sup 239}Pu and {sup 240}Pu concentrations and {sup 240}Pu/{sup 239}Pu atom ratios were measured with a double-focusing SF-ICP-MS, which was equipped with a guard electrode to eliminate secondary discharge in the plasma and to enhance overall sensitivity. In

  13. Evaluation of harvest and information needs for North American sea ducks.

    Directory of Open Access Journals (Sweden)

    Mark D Koneff

    Full Text Available Wildlife managers routinely seek to establish sustainable limits of sport harvest or other regulated forms of take while confronted with considerable uncertainty. A growing body of ecological research focuses on methods to describe and account for uncertainty in management decision-making and to prioritize research and monitoring investments to reduce the most influential uncertainties. We used simulation methods incorporating measures of demographic uncertainty to evaluate risk of overharvest and prioritize information needs for North American sea ducks (Tribe Mergini. Sea ducks are popular game birds in North America, yet they are poorly monitored and their population dynamics are poorly understood relative to other North American waterfowl. There have been few attempts to assess the sustainability of harvest of North American sea ducks, and no formal harvest strategy exists in the U.S. or Canada to guide management. The popularity of sea duck hunting, extended hunting opportunity for some populations (i.e., special seasons and/or bag limits, and population declines have led to concern about potential overharvest. We used Monte Carlo simulation to contrast estimates of allowable harvest and observed harvest and assess risk of overharvest for 7 populations of North American sea ducks: the American subspecies of common eider (Somateria mollissima dresseri, eastern and western populations of black scoter (Melanitta americana and surf scoter (M. perspicillata, and continental populations of white-winged scoter (M. fusca and long-tailed duck (Clangula hyemalis. We combined information from empirical studies and the opinions of experts through formal elicitation to create probability distributions reflecting uncertainty in the individual demographic parameters used in this assessment. Estimates of maximum growth (rmax, and therefore of allowable harvest, were highly uncertain for all populations. Long-tailed duck and American common eider appeared

  14. Developments in the North Sea and their consequences for the marine environment

    NARCIS (Netherlands)

    Eisma, D.

    1981-01-01

    Summarizing, the marine environment of the North Sea is threatened in several ways: by waterpollution, by overfishing and by bottom disturbance. Fishing is now extremely regulated, but research on and control of stocks is only extended to commercial species. Strict regulations have been made for

  15. Decadal and multi-decadal variability of Labrador Sea Water in the north-western North Atlantic Ocean derived from tracer distributions: Heat budget, ventilation, and advection

    NARCIS (Netherlands)

    van Aken, H.M.; de Jong, M.F.; Yashayaev, I.

    2011-01-01

    Time series of profiles of potential temperature, salinity, dissolved oxygen, and planetary potential vorticity at intermediate depths in the Labrador Sea, the Irminger Sea, and the Iceland Basin have been constructed by combining the hydrographic sections crossing the sub-arctic gyre of the North

  16. Potential for isoproturon, atrazine and mecoprop to be degraded within a chalk aquifer system

    Science.gov (United States)

    Johnson, Andrew C.; White, Craig; Lal Bhardwaj, C.

    2000-06-01

    The potential for herbicide degradation in an unconfined chalk aquifer was examined by collecting and spiking fresh samples and incubating them in the laboratory. The microcosms were incubated at 20°C under aerobic conditions and spiked with either isoproturon, atrazine or mecoprop at a concentration of 100 μg/l. The samples were obtained from a single fieldsite within the Upper Chalk aquifer in Hampshire, UK. Groundwater samples required the presence of sterile chalk in a ratio of at least 1:13 to promote isoproturon degradation. An isoproturon degradation potential existed in the soil, and the chalk unsaturated and saturated zones. However, no degradation of isoproturon in the unsaturated zone was observed when a more appropriate simulation of in-situ moisture conditions was carried out. Apart from the soil, no potential for atrazine or mecoprop degradation could be detected in the same samples over a 200-day incubation. In a series of groundwater samples taken from different boreholes, 10-300 m apart, large differences in isoproturon degradation potential were observed. Removal rates for 100 μg/l isoproturon varied from 83-425 ng/day, but in some samples no degradation potential could be detected. The primary metabolite which could be distinguished from isoproturon degradation in chalk and groundwater was monodesmethyl-isoproturon. When a chalk groundwater sample was spiked with isoproturon at 0.9 μg/l, this was not degraded over a 300-day incubation period. Further experiments with fresh groundwater from a Triassic Sandstone site illustrated that groundwater bacteria could degrade isoproturon at the more realistic temperature of 10°C as well as at 20°C.

  17. Changes in pollution load and environmental trends in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Pawlak, Janet

    1998-12-01

    This publication relates to the quality of the marine environment in the North Sea. Changes in pollution load and environmental trends are analysed. Main themes discussed cover chemical contaminants, temporal trends contaminants in biota, inputs of contaminants to the marine environment, and biological effects of contaminants and biological monitoring. 14 refs., 5 figs., 4 tabs.

  18. Analysis of tidal currents in the North Sea from shipboard acoustic Doppler current profiler data

    Science.gov (United States)

    Vindenes, Håvard; Orvik, Kjell Arild; Søiland, Henrik; Wehde, Henning

    2018-06-01

    North Sea tidal currents are determined by applying harmonic analysis to ship-borne acoustic Doppler current profiler data recorded from 1999 to 2016, covering large areas of the northern North Sea. Direct current measurement data sets of this magnitude are rare in the otherwise well investigated North Sea, and thus it is a valuable asset in studying and expanding our understanding of its tidal currents and circulation in general. The harmonic analysis is applied to a least squares fit of the current observations at a set of knot points. Results from the harmonic analysis compare favorably to tidal parameters estimated from observations from moored instruments. The analysis shows that the tides are characterized by strong semi-diurnal component, with amplitudes of the principal Lunar constituent ranging from 1.6 cm/s in the Skagerrak to 67 cm/s in the Fair Isle Channel. Diurnal tides are found to be approximately one fifth the strength of the predominant semi-diurnal constituent. Output from a regional barotropic tide model compares well to tidal current determined from the harmonic analysis of the Acoustic Doppler Current Profiler data.

  19. Temperature affects the timing of spawning and migration of North Sea mackerel

    DEFF Research Database (Denmark)

    Jansen, Teunis; Gislason, Henrik

    2011-01-01

    Climate change accentuates the need for knowing how temperature impacts the life history and productivity of economically and ecologically important species of fish. We examine the influence of temperature on the timing of the spawning and migrations of North Sea Mackerel using data from larvae C...

  20. Mapping Relative Sea Level Influences of the Cape Fear Arch in southern North Carolina

    Science.gov (United States)

    Hawkes, A.; Kemp, A.; Capar, P.

    2017-12-01

    Long-term relative sea-level (RSL) records are a necessary benchmark by which to gauge present accelerated rates of sea-level rise, future sea-level predictions, and their implications to the coastal zone. The east coast of the United States functions as a significant region of latitudinal RSL variability due to the continuous recovery of land from the deglaciation of the Laurentide Ice Sheet since the Last Glacial Maximum. Differential glacial isostatic adjustment (GIA) along the coastline has caused higher rates of subsidence in areas around the former forbulge maxima near New Jersey and Delaware and lower rates to the north and south of this maxima. However, the coast between southern North Carolina and northern South Carolina is experiencing a slower rate of RSL rise then is seen in reconstructed GIA latitudinal trends along the U.S. east coast. It was thought that this could have been attributed to non-isostatic, long-term tectonic processes causing less GIA subsidence of the lithosphere within the region impacted by uplift from the Cape Fear Arch (CFA), an underlying crystalline basement high. A recent study suggests that RSL rise is slower around the CFA than areas to the north and south due to suggested CFA uplift rates of 0.24+0.15mm a-1. An absence of RSL records for 200km north of the CFA make mapping of its influence difficult. Additional RSL records to the north of the CFA allow for a better understanding of the asymmetrical distribution in the rate of RSL rise in this region. Because the distribution in the rate of RSLR between records is not linear it is important for these low-lying coastal communities to better understand their risk to future RSLR.

  1. Bathymetric controls on Pliocene North Atlantic and Arctic sea surface temperature and deepwater production

    Science.gov (United States)

    Robinson, M.M.; Valdes, P.J.; Haywood, A.M.; Dowsett, H.J.; Hill, D.J.; Jones, S.M.

    2011-01-01

    The mid-Pliocene warm period (MPWP; ~. 3.3 to 3.0. Ma) is the most recent interval in Earth's history in which global temperatures reached and remained at levels similar to those projected for the near future. The distribution of global warmth, however, was different than today in that the high latitudes warmed more than the tropics. Multiple temperature proxies indicate significant sea surface warming in the North Atlantic and Arctic Oceans during the MPWP, but predictions from a fully coupled ocean-atmosphere model (HadCM3) have so far been unable to fully predict the large scale of sea surface warming in the high latitudes. If climate proxies accurately represent Pliocene conditions, and if no weakness exists in the physics of the model, then model boundary conditions may be in error. Here we alter a single boundary condition (bathymetry) to examine if Pliocene high latitude warming was aided by an increase in poleward heat transport due to changes in the subsidence of North Atlantic Ocean ridges. We find an increase in both Arctic sea surface temperature and deepwater production in model experiments that incorporate a deepened Greenland-Scotland Ridge. These results offer both a mechanism for the warming in the North Atlantic and Arctic Oceans indicated by numerous proxies and an explanation for the apparent disparity between proxy data and model simulations of Pliocene northern North Atlantic and Arctic Ocean conditions. Determining the causes of Pliocene warmth remains critical to fully understanding comparisons of the Pliocene warm period to possible future climate change scenarios. ?? 2011.

  2. Porosity and sonic velocity depth trends of Eocene chalk in Atlantic Ocean: Influence of effective stress and temperature

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Fabricius, Ida Lykke

    2014-01-01

    We aimed to relate changes in porosity and sonic velocity data, measured on water-saturated Eocene chalks from 36 Ocean Drilling Program drill sites in the Atlantic Ocean, to vertical effective stress and thermal maturity. We considered only chalk of Eocene age to avoid possible influence...... not show or at least it is difficult to define a clear pore-stiffening contact cementation trend as the Ontong Java Plateau chalk. Mechanical compaction is the principal cause of porosity reduction (at shallow depths) in the studied Eocene chalk, at least down to about 5MPa Terzaghi׳s effective stress...

  3. Trophic impact of Atlantic bluefin tuna migrations in the North Sea

    DEFF Research Database (Denmark)

    Mariani, Patrizio; Andersen, Ken Haste; Lindegren, Martin

    2017-01-01

    and the stability of the fish community. The impact of a migrating top-predator is investigated here for Atlantic bluefin tuna in the North Sea. Bluefin tuna has been absent from the region for half-century, but recent years have seen recovery of migrations and a return of bluefin tuna in the area. We use a size...

  4. Integrated North Sea grids: The costs, the benefits and their distribution between countries

    International Nuclear Information System (INIS)

    Konstantelos, Ioannis; Pudjianto, Danny; Strbac, Goran; De Decker, Jan; Joseph, Pieter; Flament, Aurore; Kreutzkamp, Paul; Genoese, Fabio; Rehfeldt, Leif; Wallasch, Anna-Kathrin; Gerdes, Gerhard; Jafar, Muhammad; Yang, Yongtao; Tidemand, Nicolaj; Jansen, Jaap; Nieuwenhout, Frans; Welle, Adriaan van der; Veum, Karina

    2017-01-01

    A large number of offshore wind farms and interconnectors are expected to be constructed in the North Sea region over the coming decades, creating substantial opportunities for the deployment of integrated network solutions. Creating interconnected offshore grids that combine cross-border links and connections of offshore plants to shore offers multiple economic and environmental advantages for Europe's energy system. However, despite evidence that integrated solutions can be more beneficial than traditional radial connection practices, no such projects have been deployed yet. In this paper we quantify costs and benefits of integrated projects and investigate to which extent the cost-benefit sharing mechanism between participating countries can impede or encourage the development of integrated projects. Three concrete interconnection case studies in the North Sea area are analysed in detail using a national-level power system model. Model outputs are used to compute the net benefit of all involved stakeholders under different allocation schemes. Given the asymmetric distribution of costs and benefits, we recommend to consistently apply the Positive Net Benefit Differential mechanism as a starting point for negotiations on the financial closure of investments in integrated offshore infrastructure. - Highlights: • Three North Sea offshore gird case studies are analysed. • They are shown to have substantial net benefit over non-integrated network designs. • Asymmetric net benefit sharing between countries is shown to be a barrier. • Positive Net Benefit Differential method alleviates asymmetric benefits.

  5. Comparative study of air quality by the North Sea and Baltic Sea; Vergleichsuntersuchungen der Luftqualitaet an Nord- und Ostsee

    Energy Technology Data Exchange (ETDEWEB)

    Moriske, H.J.; Turowski, E.; Klar, A.; Schoendube, M.; Ebert, G.; Konieczny, L. [Umweltbundesamt, Berlin (Germany). Inst. fuer Wasser-, Boden- und Lufthygiene

    2000-01-01

    Air quality measurements were carried out in the North Sea and Baltic Sea regions. The results are summarized in this contribution from the hygienic view. [German] Im Rahmen eines Forschungsprojektes des Umweltbundesamtes, das zwischen 1996 und 1998 mit dem Titel 'Erfassung gasfoermiger und partikelfoermiger Bestandteile der Umgebungsluft an Nord- und Ostsee - Untersuchungen zur hygienischen Bedeutung des maritimen Aerosols' durchgefuehrt wurde, sollte die Frage unterschiedlicher Luftqualitaet an Nord- und Ostsee beantwortet werden und eine aktuelle Bestandsaufnahme vorgenommen werden. Der Artikel fasst die Forschungsergebnisse aus hygienischer Sicht zusammen. (orig./SR)

  6. RESULTS OF THE STUDY ORIBATIDMITEIN THE COASTAL AREA OF THE NORTH-WEST OF THE CASPIAN SEA

    Directory of Open Access Journals (Sweden)

    A. A. Grikurova

    2014-01-01

    Full Text Available Aim . Studied the fauna of the soil mites of coastal and island ecosystems of the North-Western part of the Caspian sea (Bryansk spit, Strategiczne, Islands seal, Chechen and Nordby. Found 49 species and 39 genera and subgenera, and 24 families. Species composition of oribatidmite of theNorth-western part of the Caspian Sea remains not completely studied. The aim of the work was to study the species composition of oribatidmite ecosystems of the North-Western part of the Caspian Sea. Location. Coastal ecosystems north-western part of the Caspian Sea.Methods. The selection of soil samples in different habitats and MicroStation is the basis for studying the biodiversity and abundance of soil microarthropod. To extract small soil organisms method was used electoral forcing, which is based on the use of negative phototaxis soil organisms. When the definition of oribatid mites used the microscope MBI-6, Olympus CH-20.Results. As a result of studies 41 species of oribatidmites, 9 of which – new forthe fauna of the Caucasus, 17 species – new for the fauna of Dagestan, one species – new to science were identified. There sults can be used to compile regionallists, inventories and will be included in the list of directories oribatidmite of Caucasus.Main conclusions. There sults showed that for both are as of studies - 9 species, exclusively in coastal ecosystems of Bryansks pit 24 species, found only in ecosystems Staroterechnogo 9 species are common.

  7. A synthesis of Cenozoic sedimentation in the North Sea

    DEFF Research Database (Denmark)

    Anell, Ingrid Anna Margareta; Thybo, Hans; Rasmussen, E.S.

    2012-01-01

    study provides a regional synthesis of sedimentation based on a comprehensive interpretation of a regionally covering reflection seismic data set. We relate observations of sediment characteristics and unconformities to the geological evolution. The timing, regional expression and stratigraphic...... characteristics of many unconformities indicate that they were generated by eustatic sea-level fall, often in conjunction with other processes. Early Cenozoic unconformities, however, relate to tectonism associated with the opening of the North Atlantic. From observation on a regional scale, we infer...

  8. The End of "Chalk and Talk"

    Science.gov (United States)

    Barlow, Tim

    2012-01-01

    "Chalk and talk" had been the staple pedagogical approach of my Science teaching practice since entering the profession. I felt that there was a great deal of information that I must impart to my students. My tried and tested way to deliver information to my students had always been simply to stand in front of them and tell it to them... So what…

  9. In situ flume measurements of resuspension in the North Sea

    Science.gov (United States)

    Thompson, C. E. L.; Couceiro, F.; Fones, G. R.; Helsby, R.; Amos, C. L.; Black, K.; Parker, E. R.; Greenwood, N.; Statham, P. J.; Kelly-Gerreyn, B. A.

    2011-07-01

    The in situ annular flume, Voyager II, was deployed at three sites in the North Sea in order to investigate resuspension events, to determine the physical characteristics of the seabed, to determine the threshold of resuspension of the bed and to quantify erosion rates and erosion depths. These are the first controlled, in situ flume experiments to study resuspension in the North Sea, and were combined with long-term measurements of waves and currents. Resuspension experiments were undertaken at two muddy, and one sandy site: north of the Dogger Bank (DG: water depths ˜80 m, very fine, poorly sorted, very fine-skewed sediment experiencing seasonal thermal stratification of the water column along with oxygen depletion); the Oyster Grounds (OG: ˜40 m, similar bed properties, year round water column thermal stratification, Atlantic forcing); and in the Sean Gas Field (SGF: ˜20 m, moderately sorted, very coarse-skewed sand, and well mixed water column). The erosion thresholds of the bed were found to be 0.66-1.04 Pa (DG) and 0.91-1.27 Pa (OG), with corresponding erosion depths of 0.1-0.15 mm and 0.02-0.06 mm throughout the experiments. Evaluation of a year of current velocities from 2007 indicated that at OG, resuspension of the consolidated bed was limited to on average ˜8% of the time as a result of tidal forcing alone for short (properties of the bed. Therefore, while complex variations in biogeophysical factors affected the critical threshold of erosion, once exceeded, erosion rates were related to the nature of the sediment.

  10. Submarine pipelines and the North Sea environment

    International Nuclear Information System (INIS)

    Haldane, D.; Paul, M.A.; Reuben, R.L.; Side, J.C.

    1992-01-01

    The function and design of pipelines for use on the United Kingdom continental shelf are described. Environmental influences which can threaten the integrity of seabed pipelines in the North Sea include hydrodynamic forces due to residual, tidal and wave currents, the nature of seabed sediments and corrosion by seawater. Damage may be caused to pipelines by interaction with vessel anchors and with fishing gear. Special care has to be taken over the selection of the general area for the landfall of a pipeline and the engineering of the installation where the pipeline comes ashore. Trenching and other protection techniques for pipelines are discussed together with hydrostatic testing and commissioning and subsequent inspection, maintenance and repair. (UK)

  11. Deposition of nitrogen into the North Sea

    DEFF Research Database (Denmark)

    Leeuw, G. de; Skjøth, C.A.; Hertel, O.

    2003-01-01

    The flux of nitrogen species from the atmosphere into the ocean, with emphasis on coastal waters, was addressed during the ANICE project (Atmospheric Nitrogen Inputs into the Coastal Ecosystem). ANICE focused on quantifying the deposition of atmospheric inputs of inorganic nitrogen compounds (HNO3...... and Harwich/Newcastle. These measurements provided data for sensitivity studies of a variety of problems associated with the coastal region that are not easily evaluated with larger scale models, to constrain models and to test model results. Concentrations of nitrogen compounds over the North Sea...... on experimental results and small-scale model studies. In particular, effects of the aerosol size distribution on the nitrogen deposition are discussed. (C) 2003 Elsevier Ltd. All rights reserved....

  12. Early Permian intrusions in the Paleozoic sediments of the Eastern North Sea area

    DEFF Research Database (Denmark)

    Clausen, O.R.; Andresen, Katrine Juul; Rasmussen, Jens Andreas

    in the Northern Permian Basin which in the eastern North Sea is separated from the Southern Permian Basin by the Ringkøbing-Fyn High. The Permian basins were initiated during thermal subsidence following a late Carboniferous- early Permian rifting phase associated with extensive igneous activity recorded across...... the entire North Sea Basin. The easternmost intrusions and extrusions have been associated to the “Skagerrak-Centered Large Igneous Province” that has an early Permian age of c. 297 Ma. Compared to the Southern Permian Basin which historically has been intensely investigated because of the known presence...... of hydrocarbons within the Paleozoic sediments, the Northern Permian Basin has gained much less interest outside the hydrocarbon producing Mesozoic graben systems. This is mainly due to an apparent lack of potential source rocks. A major E-W striking northward dipping fault system characterizes the study area...

  13. Sea surface temperature and sea ice variability in the subpolar North Atlantic from explosive volcanism of the late thirteenth century

    DEFF Research Database (Denmark)

    Sicre, M. -A.; Khodri, M.; Mignot, J.

    2013-01-01

    In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and long......-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling...... and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades....

  14. Integrated management plan for the North Sea and the Skagerrak: Impact assessment for renewable energy production in the North Sea; Helhetlig forvaltningsplan for Nordsjoen og Skagerrak. Konsekvenser av fornybar energiproduksjon i Nordsjoen.

    Energy Technology Data Exchange (ETDEWEB)

    Nybakke, Karen

    2011-07-01

    This is one of six sectorial assessments which will form the basis for a general management plan for the North Sea and the Skagerrak. The (environmental) impact assessment is limited to 6 areas.(Author)

  15. The Effect of Bacteria Penetration on Chalk Permeability

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Shapiro, Alexander; Nielsen, Sidsel Marie

    number of B. licheniformis was detected on the effluent compared with P. putida. However, in the experiment with B. licheniformis mainly spores were detected in the effluent. The core permeability decreased rapidly during injection of bacteria and a starvation period of 12 days did not allow......Bacteria selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery. Bacteria can plug the water-bearing zones of a reservoir, thus altering the flow paths and improving sweep efficiency. It is known that the bacteria can penetrate deeply...... into reservoirs, however, a complete understanding of the penetration behavior of bacteria is lacking, especially in chalk formations where the pore throat sizes are almost comparable with the sizes of bacteria vegetative cells. This study investigates the penetration of bacteria into chalk. Two bacteria types...

  16. Emerald oil field on production in North Sea

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that Midland and Scottish Energy Ltd. (MSE) has placed Emerald oil field on stream in the U.K. North Sea with a floating production unit. Initial production, from two satellite wells, will be used to commission facilities. Three water injection wells have been unplugged and are ready for start-up. MSE will place a central cluster of wells-five producers and one water injector-on stream during the next few weeks. Production will build to an expected 25,000 b/d from 35 million bbl of reserves. Field development has undergone an unusually large number of setbacks and changes

  17. Anthropogenic {sup 129}I in the North Pacific, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, H., E-mail: hnagai@chs.nihon-u.ac.jp [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Hasegawa, A. [Graduate School of Integrated Basic Sciences, Nihon University, Tokyo 156-8550 (Japan); Yamagata, T. [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Kumamoto, Y.; Nishino, S. [Japan Agency for Marine-Earth Science and Technology, Kanagawa 237-0061 (Japan); Matsuzaki, H. [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo 113-0032 (Japan)

    2015-10-15

    Most of anthropogenic {sup 129}I in marine environment are due to discharge from the nuclear fuel reprocessing facilities at Sellafield (U.K.) and La Hague (France) for past few decades. The discharge raised {sup 129}I concentration in seawaters in the North Atlantic and Arctic Oceans to more than 10{sup 9} atoms L{sup −1}, which is two orders of magnitude higher than that in other region. Recently, in March 2011, a large quantity of {sup 129}I was released into the western North Pacific due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. To evaluate the influence of these events, we have measured {sup 129}I concentration in seawaters in the northern North Pacific Ocean, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013. The {sup 129}I concentrations were 1.0–1.8 × 10{sup 7} atoms L{sup −1} in the surface waters in the vicinity of 47°N 150°E–130°W North Pacific Ocean, Bering Sea, and Chukchi Sea (<74°N), which are equal to or lower than the {sup 129}I concentration level in surface water in the North Pacific Ocean before the F1NPP accident. The vertical profiles in the North Pacific were almost same as that observed in the western North Pacific before the F1NPP accident. The {sup 129}I distribution in seawater in the North Pacific to the Chukchi Sea revealed no significant increase of {sup 129}I concentration caused by the F1NPP accident. The {sup 129}I concentrations were 13–14 × 10{sup 7} atoms L{sup −1} in surface waters and 80 × 10{sup 7} atoms L{sup −1} at depths of 300 and 800 m in the Arctic Ocean.

  18. Sulfate-Reducing Prokaryotes from North Sea Oil reservoirs; organisms, distribution and origin

    Energy Technology Data Exchange (ETDEWEB)

    Beeder, Janiche

    1997-12-31

    During oil production in the North Sea, anaerobic seawater is pumped in which stimulates the growth of sulphate-reducing prokaryotes that produce hydrogen sulphide. This sulphide causes major health hazards, economical and operational problems. As told in this thesis, several strains of sulphate reducers have been isolated from North Sea oil field waters. Antibodies have been produced against these strains and used to investigate the distribution of sulphate reducers in a North Sea oil reservoir. The result showed a high diversity among sulphate reducers, with different strains belonging to different parts of the reservoir. Some of these strains have been further characterized. The physiological and phylogenetic characterization showed that strain 7324 was an archaean. Strain A8444 was a bacterium, representing a new species of a new genus. A benzoate degrading sulphate reducing bacterium was isolated from injection water, and later the same strain was detected in produced water. This is the first field observations indicating that sulphate reducers are able to penetrate an oil reservoir. It was found that the oil reservoir contains a diverse population of thermophilic sulphate reducers able to grow on carbon sources in the oil reservoir, and to live and grow in this extreme environment of high temperature and pressure. The mesophilic sulphate reducers are established in the injection water system and in the reservoir near the injection well during oil production. The thermophilic sulphate reducers are able to grow in the reservoir prior to, as well as during production. It appears that the oil reservoir is a natural habitat for thermophilic sulphate reducers and that they have been present in the reservoir long before production started. 322 refs., 9 figs., 11 tabs.

  19. Priority volatile organic compounds in surface waters of the southern North Sea

    International Nuclear Information System (INIS)

    Huybrechts, Tom; Dewulf, Jo; Langenhove, Herman van

    2005-01-01

    The occurrence of 25 volatile organic compounds (VOCs) was studied from April 1998 to October 2000 in the southern North Sea. Target VOCs were selected from lists of priority pollutants for the marine environment and included, e.g., chlorinated short-chain hydrocarbons (CHCs), monocyclic aromatic hydrocarbons (MAHs), and chlorinated monocyclic aromatic hydrocarbons (CMAHs). Water samples were taken from the Channel, the Belgian Continental Shelf, the mouth of the Scheldt estuary and the Southern Bight, and were analysed by purge-and-trap and high-resolution gas chromatography-mass spectrometry. All data were produced by analyses deemed 'in control' by a rigorous quality assurance/quality control program provided by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe). Chloroform and trichloroethene were commonly detected at concentrations up to 1900 and 270 ng l -1 , respectively. The other CHCs were generally found below 5 ng l -1 , and rarely exceeded 10 ng l -1 . Concentrations of MAHs were at least one order of magnitude higher than those of the CHCs. The higher levels were attributed to anthropogenic emissions from oil-related activities in coastal areas. CMAHs, except chlorobenzene and 1,4-dichlorobenzene, were hardly detected in North Sea waters. The levels of several CHCs and MAHs were shown to decrease compared to previous investigations in 1994-1995, probably as a result of on-going emission reduction efforts. The occurrence of 1,1,1-trichloroethane, for instance, was substantially reduced since the Montreal Protocol was implemented in 1995. - Volatile aromatics are a major group of volatile organic compounds in the North Sea, and are attributed to discharges from shipping and oil related activities

  20. Sulfate-Reducing Prokaryotes from North Sea Oil reservoirs; organisms, distribution and origin

    Energy Technology Data Exchange (ETDEWEB)

    Beeder, Janiche

    1996-12-31

    During oil production in the North Sea, anaerobic seawater is pumped in which stimulates the growth of sulphate-reducing prokaryotes that produce hydrogen sulphide. This sulphide causes major health hazards, economical and operational problems. As told in this thesis, several strains of sulphate reducers have been isolated from North Sea oil field waters. Antibodies have been produced against these strains and used to investigate the distribution of sulphate reducers in a North Sea oil reservoir. The result showed a high diversity among sulphate reducers, with different strains belonging to different parts of the reservoir. Some of these strains have been further characterized. The physiological and phylogenetic characterization showed that strain 7324 was an archaean. Strain A8444 was a bacterium, representing a new species of a new genus. A benzoate degrading sulphate reducing bacterium was isolated from injection water, and later the same strain was detected in produced water. This is the first field observations indicating that sulphate reducers are able to penetrate an oil reservoir. It was found that the oil reservoir contains a diverse population of thermophilic sulphate reducers able to grow on carbon sources in the oil reservoir, and to live and grow in this extreme environment of high temperature and pressure. The mesophilic sulphate reducers are established in the injection water system and in the reservoir near the injection well during oil production. The thermophilic sulphate reducers are able to grow in the reservoir prior to, as well as during production. It appears that the oil reservoir is a natural habitat for thermophilic sulphate reducers and that they have been present in the reservoir long before production started. 322 refs., 9 figs., 11 tabs.

  1. Analysis of fine-dispersed chalk usage as mineral additive in the composition of sand aggrerate concrete

    Directory of Open Access Journals (Sweden)

    Светлана Николаевна Чепурная

    2016-12-01

    Full Text Available The research results of fine-disperse chalk addition on physical and mechanical properties of the cement stone and concrete are shown. It is determined that fine-disperse chalk addition in the binder composition increases the content of ultrafine particles. The chalk particles fill the pore space between the cement particles, increasing the packing density, which leads to a density increase, which consequently leads to improved physical and mechanical properties of the concrete: water tightness, cold resistance, corrosion resistance, crack resistance and other properties

  2. Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

    NARCIS (Netherlands)

    Kürten, B.; Frutos, I.; Struck, U.; Painting, S.J.; Polunin, N.V.C.; Middelburg, J.J.

    The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs).

  3. Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

    NARCIS (Netherlands)

    Kürten, B.; Frutos, I.; Struck, U.; Painting, S.J.; Polunin, N.V.C.; Middelburg, J.J.

    2013-01-01

    The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs).

  4. Permeability, porosity, dispersion-, diffusion-, and sorption characteristics of chalk samples from Erslev, Mors, Denmark

    International Nuclear Information System (INIS)

    Carlsen, L.; Batsberg, W.; Skytte Jensen, B.; Bo, P.

    1981-08-01

    A series of chalk samples from the cretaceous formation overlying the Erslev salt dome have been studied in order to establish permeabilities, porosities, dispersion-, diffusion-, and sorption characteristics of the chalk, Predominantly the investigations have been carried out by application of a liquid chromatographic technique. The chalk was found to be porous (epsilon approximately 0.4), however, of rather low permeability (k approximately 10 -7 cm/sec). It was found that the material exhibits a retarding effect on the migration of cationic species as Cs + , Sr 2+ , Co 2+ , and Eu 3+ , whereas anionic species as Cl - and TcO - 4 move with the water front. The geochemical implications are discussed. (author)

  5. Potential contribution of surface-dwelling Sargassum algae to deep-sea ecosystems in the southern North Atlantic

    Science.gov (United States)

    Baker, Philip; Minzlaff, Ulrike; Schoenle, Alexandra; Schwabe, Enrico; Hohlfeld, Manon; Jeuck, Alexandra; Brenke, Nils; Prausse, Dennis; Rothenbeck, Marcel; Brix, Saskia; Frutos, Inmaculada; Jörger, Katharina M.; Neusser, Timea P.; Koppelmann, Rolf; Devey, Colin; Brandt, Angelika; Arndt, Hartmut

    2018-02-01

    Deep-sea ecosystems, limited by their inability to use primary production as a source of carbon, rely on other sources to maintain life. Sedimentation of organic carbon into the deep sea has been previously studied, however, the high biomass of sedimented Sargassum algae discovered during the VEMA Transit expedition in 2014/2015 to the southern North Atlantic, and its potential as a regular carbon input, has been an underestimated phenomenon. To determine the potential for this carbon flux, a literature survey of previous studies that estimated the abundance of surface water Sargassum was conducted. We compared these estimates with quantitative analyses of sedimented Sargassum appearing on photos taken with an autonomous underwater vehicle (AUV) directly above the abyssal sediment during the expedition. Organismal communities associated to Sargassum fluitans from surface waters were investigated and Sargassum samples collected from surface waters and the deep sea were biochemically analyzed (fatty acids, stable isotopes, C:N ratios) to determine degradation potential and the trophic significance within deep-sea communities. The estimated Sargassum biomass (fresh weight) in the deep sea (0.07-3.75 g/m2) was several times higher than that estimated from surface waters in the North Atlantic (0.024-0.84 g/m2). Biochemical analysis showed degradation of Sargassum occurring during sedimentation or in the deep sea, however, fatty acid and stable isotope analysis did not indicate direct trophic interactions between the algae and benthic organisms. Thus, it is assumed that components of the deep-sea microbial food web form an important link between the macroalgae and larger benthic organisms. Evaluation of the epifauna showed a diverse nano- micro-, meio, and macrofauna on surface Sargassum and maybe transported across the Atlantic, but we had no evidence for a vertical exchange of fauna components. The large-scale sedimentation of Sargassum forms an important trophic link

  6. Contamination of North Sea and Baltic Sea with long-living iodine-129 and other anthropogenic radionuclides; Kontamination von Nord- und Ostsee mit langlebigem Iod-129 und anderen anthropogenen Radionukliden

    Energy Technology Data Exchange (ETDEWEB)

    Tosch, Luebbert

    2010-10-12

    The radionuclide iodine-129 (T{sub 1/2} = 15.7 Ma) is produced in nature by spontaneous fission of uranium-238 and by cosmic ray induced spallation of xenon. Due to the military and civil use of neutron-induced fission of uranium-235 and plutonium-239 a huge amount of iodine-129 has been released into the environment. The main sources of anthropogenic {sup 129}I are the reprocessing plants in La Hague (France) near the English Channel and in Sellafield (UK) close to the Irish Sea. The natural equilibrium {sup 129}I/{sup 127}I-isotopic ratios are estimated to 1.5 . 10{sup -12} for the marine hydrosphere and to 3.0 . 10{sup -13} for the terrestrial biosphere respectively. Due to the emissions of anthropogenic iodine-129 the {sup 129}I/{sup 127}I-isotopic ratios have been increased in all compartments of the environment. Surface water samples taken from the English Channel, the North Sea, the Baltic Sea, the Irish Sea, and the North Atlantic give information about anthropogenic changes. Iodine turns out to be a conservative tracer in seawater. The iodine-127 concentrations in seawater except for coastal areas are rather constant (40.7 ± 6.2 ng/g). The observed {sup 129}I/{sup 127}I-isotopic ratios range between 10{sup -10} and more than 10{sup -6}. The variation of the {sup 129}I/{sup 127}I-isotopic ratios is caused by the admixture of anthropogenic iodine-129. Water samples taken far away from the reprocessing plants show the lowest isotopic ratios. The highest {sup 129}I/{sup 127}I-isotopic ratios are found near the reprocessing plants. The transport of {sup 129}I from La Hague has a rather clear pattern. It can be observed along the coasts of France, Belgium, the Netherlands, Germany and Denmark. The iodine-129 emissions from Sellafield can be followed northbound along the Scottish coast. The results of other anthropogenic radionuclides are used for discussing transport processes in the North Sea and the Irish Sea. Large areas in the North Sea are characterised by

  7. Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea.

    Directory of Open Access Journals (Sweden)

    Anna Akimova

    Full Text Available Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2° hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948-2013. Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod. We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks' dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models.

  8. Benthic nutrient cycling and diagenetic pathways in the North-western Black Sea

    NARCIS (Netherlands)

    Friedrich, J.; Dinkel, C.; Friedl, G.; Pimenov, N.; Wijsman, J.W.M.; Gomoiu, M-T.; Cociasu, A.; Popa, L.; Wehrli, B.

    2002-01-01

    Benthic fluxes of nutrients and metals were measured in the coastal zone of the north-western Black Sea, which is influenced by the Danube and Dniestr rivers. The results from the benthic flux chambers deployed during two EROS 21 cruises in summer 1995 and in spring 1997 yield information on benthic

  9. Biot Critical Frequency Applied as Common Friction Factor for Chalk with Different Pore Fluids and Temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    Injection of water into chalk hydrocarbon reservoirs has lead to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. Water has a significant softening effect on elastic...... and we propose that the fluid effect on mechanical properties of highly porous chalk may be the result of liquid‐solid friction. Applying a different strain or stress rate is influencing the rock strength and needs to be included. The resulting function is shown to relate to the material dependent...... and rate independent b-factor used when describing the time dependent mechanical properties of soft rock or soils. As a consequence it is then possible to further characterize the material constant from the porosity and permeability of the rock as well as from pore fluid density and viscosity which...

  10. Variability and Dynamics of Dissolved Oxygen in the Transition Zone of the North Sea and the Baltic Sea

    DEFF Research Database (Denmark)

    Jonasson, Lars

    information about the seasonal to decadal oxygen variations in the bottom water of the Kattegat, the Danish Straits, the Sound and the Western Baltic Sea and investigates the relative importance of physical and biogeochemical processes, climate change and nutrient load reductions on the oxygen variability......The bottom water in the transition zone of the North Sea and Baltic Sea suffers from seasonal hypoxia, usually during late summer and autumn. Hypoxia is a natural phenomenon in this region because of the strong vertical stratification which prevents the bottom water to be ventilated by atmospheric...... concentrations by 15-30 μmol O2 l−1 yr−1 while the reduced nutrient concentration has increased the oxygen concentration with approximately the same amount. Thus, the positive effect on oxygen conditions from reduced nutrient concentrations have been counteracted by increased water temperatures. This has made...

  11. A Triple P review of the feasibility of sustainable offshore seaweed production in the North Sea

    NARCIS (Netherlands)

    Burg, van den S.W.K.; Stuiver, M.; Veenstra, F.A.; Bikker, P.; Lopez Contreras, A.M.; Palstra, A.P.; Broeze, J.; Jansen, H.M.; Jak, R.G.; Gerritsen, A.L.; Harmsen, P.F.H.; Kals, J.; Blanco Garcia, A.; Brandenburg, W.A.; Krimpen, van M.M.; Duijn, van A.P.; Mulder, W.J.; Raamsdonk, van L.W.D.

    2013-01-01

    This study focused on the potential of seaweed, cultivated in the North Sea, as a sustainable and profitable resource for feed and non-food applications. Seawood production can take place as part of multi-use platforms at sea (MUPS). A review of the state-of-the-art in seaweed production and its

  12. Climate drift of AMOC, North Atlantic salinity and arctic sea ice in CFSv2 decadal predictions

    Science.gov (United States)

    Huang, Bohua; Zhu, Jieshun; Marx, Lawrence; Wu, Xingren; Kumar, Arun; Hu, Zeng-Zhen; Balmaseda, Magdalena A.; Zhang, Shaoqing; Lu, Jian; Schneider, Edwin K.; Kinter, James L., III

    2015-01-01

    There are potential advantages to extending operational seasonal forecast models to predict decadal variability but major efforts are required to assess the model fidelity for this task. In this study, we examine the North Atlantic climate simulated by the NCEP Climate Forecast System, version 2 (CFSv2), using a set of ensemble decadal hindcasts and several 30-year simulations initialized from realistic ocean-atmosphere states. It is found that a substantial climate drift occurs in the first few years of the CFSv2 hindcasts, which represents a major systematic bias and may seriously affect the model's fidelity for decadal prediction. In particular, it is noted that a major reduction of the upper ocean salinity in the northern North Atlantic weakens the Atlantic meridional overturning circulation (AMOC) significantly. This freshening is likely caused by the excessive freshwater transport from the Arctic Ocean and weakened subtropical water transport by the North Atlantic Current. A potential source of the excessive freshwater is the quick melting of sea ice, which also causes unrealistically thin ice cover in the Arctic Ocean. Our sensitivity experiments with adjusted sea ice albedo parameters produce a sustainable ice cover with realistic thickness distribution. It also leads to a moderate increase of the AMOC strength. This study suggests that a realistic freshwater balance, including a proper sea ice feedback, is crucial for simulating the North Atlantic climate and its variability.

  13. Mixed fisheries forecasts—lessons learned from their initial application to North Sea fisheries

    DEFF Research Database (Denmark)

    Holmes, S.J.; Ulrich, Clara; Reeves, S.A.

    2012-01-01

    the work with the existing single‐stock assessments. The explicit representation of the complexity of the fisheries also raises questions about the extent to which mixed fisheries science can be used to give ”advice” in the traditional sense. This paper addresses the challenges and issues that have arisen......Mixed fisheries and technical interactions in European fisheries have been a subject of research for many years. The establishment in 2010 of an ICES Working Group tasked with producing annual mixed fisheries forecasts and advice for North Sea demersal fisheries represents a commitment to use...... these approaches in routine scientific advice for the first time. The demersal fisheries of the North Sea provide a particularly interesting context for this work because of their high complexity in terms of the numbers of fleets, gears, métiers, and species involved, and also because mixedfishery effects have...

  14. 'Save the North Sea' Fulmar Study 2002-2004: a regional pilot project for the Fulmar-Litter-EcoQO in the OSPAR area

    NARCIS (Netherlands)

    Franeker, van J.A.; Heubeck, M.; Fairclough, K.; Turner, D.M.; Grantham, M.; Stienen, E.W.M.; Guse, N.; Pedersen, J.; Olsen, K.O.; Andersson, P.J.; Olsen, B.

    2005-01-01

    North Sea Ministers at the Bergen Conference in 2002 decided that monitoring of marine plastic litter in stomachs of seabirds should become one of the 'Ecological Quality Objectives for the North Sea (EcoQO's)'. The task of implementation was delegated to OSPAR, which covers the wider northeast

  15. Marine environment protection for the North and Baltic Seas. Special Report - February 2004

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The marine environment of the North Sea and Baltic Sea is still heavily polluted. The marine ecosystems are under severe stress from overfishing, water pollution, raw materials production and tourism. Environmental protection in this region necessitates decisive political initiatives and strict corrections especially in fishery policy, agricultural policy and chemical substances control. This is the balance of the special expert opinion of the Council of Environmental Experts. The publication specifies the main problem areas, the current pollution situation, the fields where action is most urgently required - especially in fishery, chemical substances, agricultural and sea travel policies - and presents suggestions for an integrated European and national marine protection policy including a regional development concept for the marine environment. (orig.)

  16. The North Seas Countries' Offshore Grid Initiative. Initial Findings. Final Report. Working Group 1 - Grid Configuration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-15

    This report focuses on the tasks and results from Working Group 1 (WG1), grid configuration and integration, chaired jointly by representatives from Denmark and the Netherlands. The methodology, assumptions concerning generation portfolio, load situation, available technology and results are presented. This report presents the WG1 Offshore Grid Study that supports the North Seas Countries' Offshore Grid Initiative (NSCOGI) final report. The information contained in this report aims to evaluate the long-term development of an offshore grid structure in the North Seas by providing a view on how such a grid may possibly develop in the future, based on the assumptions made for this study. The report aims to compare and evaluate the possible advantages and disadvantages of the long term development of an optimised, integrated (or meshed) offshore grid in the North Seas by providing a view of how that possible grid might develop in the future against changes to the electricity energy requirements. To evaluate basic variants, different transmission design topologies (radial and meshed) were compared and analysed with respect to various aspects, such as cost/benefits, import and export levels and the systems' CO2 emissions.

  17. A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

    Directory of Open Access Journals (Sweden)

    Suzanne Caroline Marianne Haaijer

    2013-03-01

    Full Text Available Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite-oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB, a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifiying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (AOB and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmoles of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on FISH and metagenomic data converting a maximum of 3 mmoles of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity. Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted PCR analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species.

  18. A summary of the Chalk River valve packing evaluation program 1985 - 1990

    International Nuclear Information System (INIS)

    Aikin, J.A.; Doubt, G.L.; Lade, C.R.

    1990-12-01

    The move away from asbestos-based valve packing products has generated concern among valve manufacturers, packing manufacturers and user groups about the reliability and safety of non-asbestos based products for long-term use. AECL Research, Chalk River, has been actively evaluating these new valve packing products since 1985. This report describes the work done at Chalk River from 1985 to 1990. The report includes both Electric Power Research Institute (EPRI) and CANDU Owners Group (COG) funded studies. A description of the test programs and a brief summary of the functional performance of the more successful materials (die-formed graphite, braided asbestos and braided non-asbestos) on friction, stem leakage and consolidation are provided. At this time, Chalk River and Ontario Hydro have approved the following packing arrangements: for non-live-loaded valves, the recommended replacements packing for braided asbestos is combination flexible graphite packing sets; and, for heavy water valves originally designed with JC187I, the recommended replacement packing is approved braided-asbestos products

  19. Connectivity of larval cod in the transition area between North Sea and Baltic Sea and potential implications for fisheries management

    DEFF Research Database (Denmark)

    Huwer, Bastian; Hinrichsen, H.-H.; Hüssy, Karin

    2016-01-01

    in the transition area between North Sea and Baltic were investigated to (i) determine long-term trends and variability in advective transport of larvae from spawning grounds to juvenile nursery areas, (ii) estimate the degree of exchange between different management areas, and (iii) compare the results...

  20. Temporal changes in plankton of the North Sea: community shfits and environmental drivers

    NARCIS (Netherlands)

    Alvarez-Fernandez, S.; Lindeboom, H.J.; Meesters, H.W.G.

    2012-01-01

    This paper analyses long-term and seasonal changes in the North Sea plankton community during the period 1970 to 2008. Based on Continuous Plankton Recorder (CPR) data covering 38 yr, major changes in both phytoplankton and zooplankton abundance and community structure were identified. Regime

  1. Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

    Science.gov (United States)

    Xiao, Ziniu; Li, Delin

    2016-06-01

    The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

  2. Nano sized clay detected on chalk particle surfaces

    DEFF Research Database (Denmark)

    Skovbjerg, Lone; Hassenkam, Tue; Makovicky, Emil

    2012-01-01

    that in calcite saturated water, both the polar and the nonpolar functional groups adhere to the nano sized clay particles but not to calcite. This is fundamentally important information for the development of conceptual and chemical models to explain wettability alterations in chalk reservoirs...

  3. Marine macrofossil communities in the uppermost Maastrichtian chalk of Stevns Klint, Denmark

    DEFF Research Database (Denmark)

    Hansen, Thomas; Surlyk, Finn

    2014-01-01

    Three successive marine habitats and their benthic macrofossil communities have been recognised and assessed in the uppermost Maastrichtian chalk of Stevns Klint, Denmark. The mound-bedded lower Sigerslev Member was deposited below the photic zone under the influence of persistent, non-erosive bo......Three successive marine habitats and their benthic macrofossil communities have been recognised and assessed in the uppermost Maastrichtian chalk of Stevns Klint, Denmark. The mound-bedded lower Sigerslev Member was deposited below the photic zone under the influence of persistent, non...

  4. North Sea market update: Changes in both concept and content

    International Nuclear Information System (INIS)

    Scruton, M.; Bru, J.G.

    1997-01-01

    The current paradox facing the North Sea offshore industry is that while it is experiencing a current market boom, within two years contractors may be scrambling around in a much reduced market. West Europe is running at a massive $15.1 billion. A veritable feast giving contractors, especially in Norway, a full workload and the headache of a severe skilled workforce shortage. Themes discussed cover Norwegian needs, Danish developments, UK utilisation, Dutch demand, and new breed. 4 figs

  5. Genetic population structure of turbot ( Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea

    DEFF Research Database (Denmark)

    Eg Nielsen, Einar; Nielsen, P.H.; Meldrup, Dorte

    2004-01-01

    Sea, suggesting high gene flow among populations in these areas. In contrast, there was a sharp cline in genetic differentiation going from the low saline Baltic Sea to the high saline North Sea. The data were explained best by two divergent populations connected by a hybrid zone; however......, a mechanical mixing model could not be ruled out. A significant part of the genetic variance could be ascribed to variation among years within locality. Nevertheless, the population structure was relatively stable over time, suggesting that the observed pattern of genetic differentiation is biologically...... significant. This study suggests that hybrid zones are a common phenomenon for marine fishes in the transition area between the North Sea and the Baltic Sea and highlights the importance of using interspecific comparisons for inferring population structure in high gene flow species such as most marine fishes....

  6. Ecologically least vulnerable sites for exploration drilling in the Wadden Sea and the North Sea coastal area

    International Nuclear Information System (INIS)

    Lindeboom, H.J.; Bergman, M.J.N.; De Gee, A.

    1996-01-01

    The Dutch Oil Company (NAM, abbreviated in Dutch) applied for a number of exploration drilling in the Dutch part of the Wadden Sea and the North Sea coastal area. NAM is obliged to draft a so-called MER (environmental impact report) to indicate the most environment-friendly alternative for the test drilling. By order of NAM, NIOZ and the IBN-DLO (Institute for Research on Forests and Nature) analyzed samples of the animal life in all the potential sites. Based on the results of the analyses, literature and expert knowledge the ecologically least vulnerable sites and the ecologically least vulnerable season were selected during a workshop. In this report the results are given of the workshop, the field sample analyses and a sailing trip along the sites

  7. Recent increase of North Sea houting and prospects for recolonization in the Netherlands

    NARCIS (Netherlands)

    Kranenbarg, J.; Winter, H.V.; Backx, J.J.G.M.

    2002-01-01

    Two monitoring programmes in estuarine and freshwater systems in the Netherlands both show a recent increase in anadromous North Sea houting Coregonus oxyrhynchus after it disappeared there in the 1940s. Most houting were immature and caught during the feeding season indicating that at present the

  8. Orbital calibration of the late Campanian carbon isotope event in the North Sea

    DEFF Research Database (Denmark)

    Perdiou, Anastasios; Thibault, Nicolas; Anderskouv, Kresten

    2016-01-01

    A new record of carbon isotopes, nannofossil biostratigraphy, gamma-ray and Fe content variations is presented for the upper Campanian of the Adda-3 core, Danish Central Graben, North Sea. The studied interval provides a revision of previously assigned late Coniacian to early Santonian ages. New...

  9. Chalk Catchment Transit Time: Unresolved Issues

    Energy Technology Data Exchange (ETDEWEB)

    Darling, W. G.; Gooddy, D. C. [British Geological Survey, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom); Barker, J. A. [School of Civil Engineering and the Environment, University of Southampton, Southampton (United Kingdom); Robinson, M. [Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom)

    2013-07-15

    The mean transit time (MTT) of a catchment is the average residence time of water from rainfall to river outflow at the foot of the catchment. As such, MTT has important water quality as well as resource implications. Many catchments worldwide have been measured for MTT using environmental isotopes, yet the Chalk, an important aquifer in NW Europe, has received little attention in this regard. The catchment of the River Lambourn in southern England has been intermittently studied since the 1960s using isotopic methods. A tritium peak measured in the river during the 1970s indicates an apparent MTT of {approx}15 years, but the thick unsaturated zone (average {approx}50 m) of the catchment suggests that the MTT should be much greater because of the average downward movement through the Chalk of {approx}1 m/a consistently indicated by tritium and other tracers. Recent work in the catchment using SF{sub 6} as a residence time indicator has given groundwater ages in the narrow range 11-18 yrs, apparently supporting the river tritium data but in conflict with the unsaturated zone data even allowing for a moderate proportion of rapid bypass flow. The MTT of the catchment remains unresolved for the time being. (author)

  10. The North sea, one of the group's anchorage points

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    The North Sea is one of the pillars of the Elf Aquitaine group's Exploration-Production strategy. The most recent start-up in the North Sea, last february, concerned the Froy field where Elf Petroleum Norge (AS) is an operator with a 24.573 % interest alongside Statoil, Total Norge AS (15.2346 %) and Norsk Hydro. The first gas sales occurred on June 15, as scheduled. The oil production marketed by Elf (net of royalties) remained stable at 13.9 Gm 3 . At january 1,1995, Elf Aquitaine's mining area covered a gross surface area of 435,894 km 2 . In countries where the group is already established, the policy is : - to withdraw from exploration licenses considered as being the least promising in terms of discovery or profitability; - to concentrate on sectors where the existing production means allow for an optimisation of later developments ; - to penetrate more extensive exploration areas with good targets. In the British zone, the additional reserves revealed in the Elgin and Franklin condensate fields have doubled the initial forecast, placing the former among the major fields. All the discoveries made in the British zone have allowed the group to renew productions until now. Elf's production in Piper, Saltire, Chanter is 100,000 b/d which is added to the production of the Claymore and Scapa fields (100,000 b/d). The Flotta terminal processes the crude coming from these fields to which is added the production from the neighbouring fields of Tartan (Texaco) and Ivanhoe-Rob Roy (Amerada Hess), i.e. a total of more than 300,000 b/d. Other than Elgin or the Viking Graben, the future of the Elf group in Great Britain will most certainly come from the West Shetlands and the Irish Sea. In the Norwegian zone, the group has interest in the Frigg, Heimldal, Ekofisk, Valhall, Lille-Frigg, Froy, Oseberg, Hod, Sleipner East an Sleipner West Brage, Troll, Snorre, Statfjord East and Tordis production fields. (authors). 3 tabs., 1 photo

  11. Production of Calcareous Nannofossil Ooze for Sedimentological Experiments

    DEFF Research Database (Denmark)

    Buls, Toms; Anderskouv, Kresten; Fabricius, Ida Lykke

    2015-01-01

    by an abundance of sedimentary structures, such as drifts, moats, sediment waves, and channels documented in the Upper Cretaceous Chalk Group of NW Europe. Despite chalk being a major hydrocarbon reservoir rock of the North Sea, surprisingly little is known about the physical behavior of the pelagic carbonate......The notion of fine-grained pelagic carbonates as uniform, monotonous sequences of sediments settled in a quiescent environment has been challenged over the past few decades. Fine-grained pelagic carbonates can undergo substantial reworking after their first deposition, as illustrated...... sediment from which the chalk formed-calcareous nannofossil ooze. This poses a serious challenge to the understanding of the depositional system and the properties of facies distribution. Experimental tests, such as those performed in laboratory flumes, are necessary to provide empirical data...

  12. The impact of shipping emissions on air pollution in the greater North Sea region - Part 1: Current emissions and concentrations

    Science.gov (United States)

    Aulinger, A.; Matthias, V.; Zeretzke, M.; Bieser, J.; Quante, M.; Backes, A.

    2016-01-01

    The North Sea is one of the areas with the highest ship traffic densities worldwide. At any time, about 3000 ships are sailing its waterways. Previous scientific publications have shown that ships contribute significantly to atmospheric concentrations of NOx, particulate matter and ozone. Especially in the case of particulate matter and ozone, this influence can even be seen in regions far away from the main shipping routes. In order to quantify the effects of North Sea shipping on air quality in its bordering states, it is essential to determine the emissions from shipping as accurately as possible. Within Interreg IVb project Clean North Sea Shipping (CNSS), a bottom-up approach was developed and used to thoroughly compile such an emission inventory for 2011 that served as the base year for the current emission situation. The innovative aspect of this approach was to use load-dependent functions to calculate emissions from the ships' current activities instead of averaged emission factors for the entire range of the engine loads. These functions were applied to ship activities that were derived from hourly records of Automatic Identification System signals together with a database containing the engine characteristics of the vessels that traveled the North Sea in 2011. The emission model yielded ship emissions among others of NOx and SO2 at high temporal and spatial resolution that were subsequently used in a chemistry transport model in order to simulate the impact of the emissions on pollutant concentration levels. The total emissions of nitrogen reached 540 Gg and those of sulfur oxides 123 Gg within the North Sea - including the adjacent western part of the Baltic Sea until 5° W. This was about twice as much of those of a medium-sized industrialized European state like the Netherlands. The relative contribution of ships to, for example, NO2 concentration levels ashore close to the sea can reach up to 25 % in summer and 15 % in winter. Some hundred kilometers

  13. Mapping the spawning grounds of North Sea cod (Gadus morhua) by direct and indirect means.

    Science.gov (United States)

    Fox, Clive J; Taylor, Martin; Dickey-Collas, Mark; Fossum, Petter; Kraus, Gerd; Rohlf, Norbert; Munk, Peter; van Damme, Cindy J G; Bolle, Loes J; Maxwell, David L; Wright, Peter J

    2008-07-07

    Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey to cover the whole North Sea. Also, this survey, conducted in 2004, was the first to make extensive use of DNA-based molecular methods to unambiguously identify early developmental stage cod eggs. We compare the findings from the plankton survey with estimated egg production inferred from the distribution of mature cod in contemporaneous trawl surveys. Results from both approaches were in general agreement and showed hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands. These areas broadly coincide with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea are still active but that some localized populations may have been reduced to the point where it is now difficult to detect the presence of eggs in the plankton.

  14. Changes in the North Sea fish community: evidence of indirect effects of fishing?

    NARCIS (Netherlands)

    Daan, N.; Gislason, H.; Pope, J.G.; Rice, J.C.

    2005-01-01

    We investigate changes in the North Sea fish community with particular reference to possible indirect effects of fishing, mediated through the ecosystem. In the past, long-term changes in the slope of size spectra of research vessel catches have been related to changes in fishing effort, but such

  15. Coccolithophore assemblage response to Black Sea Water inflow into the North Aegean Sea (NE Mediterranean)

    Science.gov (United States)

    Karatsolis, B.-Th.; Triantaphyllou, M. V.; Dimiza, M. D.; Malinverno, E.; Lagaria, A.; Mara, P.; Archontikis, O.; Psarra, S.

    2017-10-01

    This study aims to presents the species composition of living coccolithophore communities in the NE Aegean Sea, investigating their spatial and temporal variations along a north-south transect in the area receiving the inflowing surface Black Sea Water (BSW) over the deeper Levantine Water (LW) layer. Coccolithophores in the area were relatively diverse and a total of 95 species over 3 sampling periods studied were recognized using Scanning Electron Microscope (SEM) techniques. R-mode hierarchical cluster analysis distinguished two coccolithophore Groups (I, IIa, IIb, IIc) with different ecological preferences. Emiliania huxleyi was the most abundant species of Group I, whereas Syracosphaera spp., Rhabdosphaera spp. and holococcolithophores were prevailing in the highly diversified Group II assemblages. Biometric analysis conducted on E. huxleyi coccoliths from Aegean water column and Black Sea sediment trap samples, indicated that during autumn, NE Aegean specimens in samples under BSW influence were featured by unimodal distribution concerning the coccolith relative tube width, with values similar to those provided by the Black Sea specimens. In early spring, coccoliths in the stations with increased BSW influx displayed a bimodal pattern of relative tube width with smaller values found mostly in the surface layers, while the distribution became again unimodal and dominated by larger values within the deeper LW layers. In the summer period, the typical LW holococcolithophore species (Group II) presented low cell numbers in the surface layer (huxleyi was almost absent in the NE Aegean during the summer sampling period.

  16. Maps of mesoscale wind variability over the North Sea region

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Hahmann, Andrea N.; Badger, Jake

    Mesoscale wind fluctuations affect the operation of wind farms, particularly as the number of geographically concentrated wind farms in the North Sea increases (Akhmatov et al. 2007). The frequency and intensity of wind fluctuations could be considered as a new siting criterion, together with exi...... for a 1 year period. The model was run with a horizontal grid spacing of 2 km. The variability maps are created by integrating the average 24 hour spectra at every grid point over different time-scales....

  17. The North Seas Countries' Offshore Grid Initiative. Initial Findings. Final Report. Working Group 1 - Grid Configuration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-15

    This report focuses on the tasks and results from Working Group 1 (WG1), grid configuration and integration, chaired jointly by representatives from Denmark and the Netherlands. The methodology, assumptions concerning generation portfolio, load situation, available technology and results are presented. This report presents the WG1 Offshore Grid Study that supports the North Seas Countries' Offshore Grid Initiative (NSCOGI) final report. The information contained in this report aims to evaluate the long-term development of an offshore grid structure in the North Seas by providing a view on how such a grid may possibly develop in the future, based on the assumptions made for this study. The report aims to compare and evaluate the possible advantages and disadvantages of the long term development of an optimised, integrated (or meshed) offshore grid in the North Seas by providing a view of how that possible grid might develop in the future against changes to the electricity energy requirements. To evaluate basic variants, different transmission design topologies (radial and meshed) were compared and analysed with respect to various aspects, such as cost/benefits, import and export levels and the systems' CO2 emissions.

  18. North Atlantic teleconnection patterns signature on sea level from satellite altimetry

    Science.gov (United States)

    Iglesias, Isabel; Lázaro, Clara; Joana Fernandes, M.; Bastos, Luísa

    2015-04-01

    Presently, satellite altimetry record is long enough to appropriately study inter-annual signals in sea level anomaly and ocean surface circulation, allowing the association of teleconnection patterns of low-frequency variability with the response of sea level. The variability of the Atlantic Ocean at basin-scale is known to be complex in space and time, with the dominant mode occurring on annual timescales. However, interannual and decadal variability have already been documented in sea surface temperature. Both modes are believed to be linked and are known to influence sea level along coastal regions. The analysis of the sea level multiannual variability is thus essential to understand the present climate and its long-term variability. While in the open-ocean sea level anomaly from satellite altimetry currently possesses centimetre-level accuracy, satellite altimetry measurements become invalid or of lower accuracy along the coast due to the invalidity of the wet tropospheric correction (WTC) derived from on-board microwave radiometers. In order to adequately analyse long-term changes in sea level in the coastal regions, satellite altimetry measurements can be recovered by using an improved WTC computed from recent algorithms that combine wet path delays from all available observations (remote sensing scanning imaging radiometers, GNSS stations, microwave radiometers on-board satellite altimetry missions and numerical weather models). In this study, a 20-year (1993-2013) time series of multi-mission satellite altimetry (TOPEX/Poseidon, Jason-1, OSTM/Jason-2, ERS-1/2, ENVISAT, CryoSat-2 and SARAL), are used to characterize the North Atlantic (NA) long-term variability on sea level at basin-scale and analyse its response to several atmospheric teleconnections known to operate on the NA. The altimetry record was generated using an improved coastal WTC computed from either the GNSS-derived path Delay or the Data Combination methodologies developed by University of

  19. Thermoluminescence dating of abyssal deposits in the north region of the South China Sea

    International Nuclear Information System (INIS)

    Peng Xiaoxian

    1988-01-01

    The ages of abyssal deposits have been studied by TL dating. The ages of the deposits from the wells Weima 1, 5 and 6 at the slope in the north of the South China Sea are 36,100 and 128 thousand years respectively

  20. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1994-10-29 to 1994-11-23 (NODC Accession 0115681)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115681 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and...

  1. The influence of riverine nitrogen on the dynamics of the North Sea oxygen minimum zone

    Science.gov (United States)

    Große, Fabian; Kreus, Markus; Lenhart, Hermann; Pätsch, Johannes

    2016-04-01

    The mitigation of eutrophication and its concomitants, like oxygen deficiency in bottom waters, is one of the major aspects of the ecological management of coastal marine ecosystems. In the past, biogeochemical models helped to significantly improve the understanding of the interaction of the physical and biological processes driving eutrophication. Anthropogenic river input of nitrogen (N) and phosphorus (P) is the main driver for eutrophication. Nevertheless, the quantification of their influence in a specific region remains an important issue, since it is as crucial for an efficient management as it is difficult to obtain. During the past decade, a quantitative method applicable to biogeochemical models - often referred to as `trans-boundary nutrient transports' (TBNT) - became more and more popular in the context of marine ecosystem management. This method allows for the tracing of elements from various sources, e.g., nitrogen (N) from different rivers, throughout the whole process chain of the applied model. By this, it provides valuable information about the contributions from different sources to the overall amount and turnover of an element in different areas of the model domain. This information constitutes the basis for the quantification, evaluation and optimisation of river input reduction targets for the tributaries, which are defined in relation to their ecological consequences in the marine environment. In existing studies, the TBNT method has been applied to a variety of biogeochemical models, e.g. to quantify the atmospheric contribution to total N in the North Sea (Troost et al., 2013). This study presents a novel approach to link the TBNT method applied to N to the biological processes driving the oxygen dynamics in the bottom layer of the North Sea. For this purpose, simulations from the biogeochemical model ECOHAM (ECOlogical model HAMburg) are analysed for the years 2002 and 2010, with the focus on the southern central North Sea, the region of

  2. Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995-2005)

    Science.gov (United States)

    Van Engeland, T.; Soetaert, K.; Knuijt, A.; Laane, R. W. P. M.; Middelburg, J. J.

    2010-09-01

    Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the robustness of the patterns against these missing data. No long-term trends in DON concentrations were found over the sampling period (1995-2005). Inter-annual variability in the different time series showed both common and station-specific behavior. The stations could be divided into two regions, based on absolute concentrations and the dominant times scales of variability. Average DON concentrations were 11 μmol l -1 in the coastal region and 5 μmol l -1 in the open sea. Organic fractions of total dissolved nitrogen (TDN) averaged 38 and 71% in the coastal zone and open sea, respectively, but increased over time due to decreasing dissolved inorganic nitrogen (DIN) concentrations. In both regions intra-annual variability dominated over inter-annual variability, but DON variation in the open sea was markedly shifted towards shorter time scales relative to coastal stations. In the coastal zone a consistent seasonal DON cycle existed with high values in spring-summer and low values in autumn-winter. In the open sea seasonality was weak. A marked shift in the seasonality was found at the Dogger Bank, with DON accumulation towards summer and low values in winter prior to 1999, and accumulation in spring and decline throughout summer after 1999. This study clearly shows that DON is a dynamic actor in the North Sea and should be monitored systematically to enable us to understand fully the functioning of this ecosystem.

  3. Human impact and environmental consequences in the North Sea and Skagerrak; Helhetlig forvaltningsplan for Nordsjoen og Skagerrak

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The expert group for the North Sea and Skagerrak has prepared six studies on human impact and environmental consequences. This is part of the technical basis for a management plan for the Norwegian part of this sea area.The expert group is requesting input on these studies from interested parties by 15 December 2011. (au)

  4. Impact of marine mercury cycling on coastal atmospheric mercury concentrations in the North- and Baltic Sea region

    Directory of Open Access Journals (Sweden)

    Johannes Bieser

    2016-06-01

    Full Text Available Abstract The cycling of mercury between ocean and atmosphere is an important part of the global Hg cycle. Here we study the regional contribution of the air-sea exchange in the North- and Baltic Sea region. We use a newly developed coupled regional chemistry transport modeling (CTM system to determine the flux between atmosphere and ocean based on the meteorological model COSMO-CLM, the ocean-ecosystem model ECOSMO, the atmospheric CTM CMAQ and a newly developed module for mercury partitioning and speciation in the ocean (MECOSMO. The model was evaluated using atmospheric observations of gaseous elemental mercury (GEM, surface concentrations of dissolved gaseous mercury (DGM, and air-sea flux (ASF calculations based on observations made on seven cruises in the western and central Baltic Sea and three cruises in the North Sea performed between 1991 and 2006. It was shown that the model is in good agreement with observations: DGM (Normalized Mean Bias NMB=-0.27 N=413, ASF (NMB=-0.32, N=413, GEM (NMB=0.07, N=2359. Generally, the model was able to reproduce the seasonal DGM cycle with the best agreement during winter and autumn (NMBWinter=-0.26, NMBSpring=-0.41, NMBSummer=-0.29, NMBAutumn=-0.03. The modelled mercury evasion from the Baltic Sea ranged from 3400 to 4000 kg/a for the simulation period 1994–2007 which is on the lower end of previous estimates. Modelled atmospheric deposition, river inflow and air-sea exchange lead to an annual net Hg accumulation in the Baltic Sea of 500 to 1000 kg/a. For the North Sea the model calculates an annual mercury flux into the atmosphere between 5700 and 6000 kg/a. The mercury flux from the ocean influenced coastal atmospheric mercury concentrations. Running CMAQ coupled with the ocean model lead to better agreement with GEM observations. Directly at the coast GEM concentrations could be increased by up to 10% on annual average and observed peaks could be reproduced much better. At stations 100km downwind

  5. A lasting legacy for the Baltic and North Sea GLOBEC Germany program

    DEFF Research Database (Denmark)

    Peck, M.A.; Dutz, Jörg; Voss, R.

    2012-01-01

    This preface introduces four manuscripts that form a special theme section of the GLOBEC Germany program within Progress in Oceanography. The four manuscripts link changes in physical forcing to the trophodynamic structure and function of the Baltic and North Seas. The target species of GLOBEC Ge...... Germany included various species of calanoid copepods and a small pelagic fish (Sprattus sprattus)...

  6. Developmental defects in pelagic embryos of several flatfish species in the Southern North sea

    Science.gov (United States)

    Cameron, P.; Berg, J.; Dethlefsen, V.; Von Westernhagen, H.

    In the spring of 1984 through and in the summer of 1987 pelagic flatfish eggs were collected in horizontal subsurface hauls with a 1-m ring net in the southern North Sea between 51°49' to 55°30'N and 2°30' to 8°00'E. The flatfish eggs were observed alive for their developmental stage and aberrations from normal development. Flatfish eggs occurring in the winter ichthyoplankton of the southern North Sea were dab, Limanda limanda; flounder. Platichthys flesus; plaice, Pleuronectes platessa, and long rough dab, Hippoglossoides platessoides. Summer samples contained dab, turbot, Psetta maxima; little sole, Buglossidium luteum; common sole, Solea solea; Norwegian topknot, Phrynorhombus norwegicus, and lemon sole, Microstomus kitt. In winter as well as in summer eggs of dab were the most abundant in the southern North Sea with up to 249 eggs·m -3 surface water in winter and 26 eggs·m -3 in summer. The investigations revealed considerable quantities of abnormally developed flatfish embryos in the plankton samples. Highest malformation rates were recorded for the early stages of dab (44.4%) followed by flounder (41.3%) and plaice (26.0%) in winter; in summer these rates were for dab 18.9%, for turbot 14.1% and for little sole 12.5%. Generally malformation rates decreased with development. Areas of high malformation rates were off the river estuaries and in near-shore areas along the Dutch and German coasts. Malformation rates decreased with the distance from the coast. Causes and effects of the occurrence of malformations during embryonic development are discussed.

  7. Structural and Lithological Controls upon Fluid Migration within the Chalk and Upper Greensand Aquifers in the Chilterns and Lambourn Downs

    OpenAIRE

    Thompson, Sally

    2002-01-01

    The influence of lithological heterogeneities, structural discontinuities and discontinuity surface mineralisation upon groundwater migration within the Chalk and the Upper Greensand of southern England has been investigated. Lithological heterogeneities in the Chalk succession include marl seams, hardgrounds, tabular flints and nodular flints. Each of these heterogeneities has a lower intrinsic porosity and permeability than in the calcite rich chalk. The influence that each of these ...

  8. Monitoring plastic ingestion by the northern fulmar Fulmarus glacialis in the North Sea

    NARCIS (Netherlands)

    Franeker, van J.A.; Blaize, C.; Danielsen, J.

    2011-01-01

    The abundance of plastics in stomachs of northern fulmars from the North Sea is used in the OSPAR Ecological Quality Objective (EcoQO) for marine litter. The preliminary EcoQO defines acceptable ecological quality as the situation where no more than 10% of fulmars exceed a critical level of 0.1 g of

  9. Kolmanda aastatuhande piraadid / kommenteerinud Peter Chalk ja Gordan Van Hook

    Index Scriptorium Estoniae

    2009-01-01

    Piraatlusest Somaalia piirkonnas ja rahvusvahelistest dokumentidest piraatluse vastu võitlemiseks 21. sajandil. Kommenteerivad uurimiskeskuse RAND Corporation vanempoliitanalüütik Peter Chalk ja transpordikompanii Maersk Line innovatsiooni ja arenduse vanemdirektor Gordan Van Hook

  10. Comparison between predicted and observed sand waves and sand banks in the North Sea

    NARCIS (Netherlands)

    Hulscher, Suzanne J.M.H.; van den Brink, G.M.

    2001-01-01

    For the first time a prediction model of regular morphological patterns on the seabed was tested against observations of sand wave and sand bank occurrence in the entire North Sea. The model, which originates from first physical principles, predicts this occurrence via two dimensionless parameters

  11. Origin of nickel in water solution of the chalk aquifer in the north of France and influence of geochemical factors

    Science.gov (United States)

    Bernard, Daniel; El Khattabi, Jamal; Lefevre, Emilie; Serhal, Hani; Bastin-Lacherez, Sabine; Shahrour, Isam

    2008-01-01

    In the north of France, high registers of nickel are sometimes recorded within the chalk aquifer. In a confined context, the presence of pyrite in the covering clays or in the marcasite nodules encrusted in the clay may constitute a natural source of trace metals. With an objective of sanitary control, the limits of chemical contents regulating the quality of water destined for human consumption have been lowered by the European Framework Directive in the field of water policy (2000/60/EC). As a result, nickel limits have been reduced from 50 to 20 μg/l. The analyses, carried out on three water catchment fields in our area of study, were centred on variable parameters (Eh, O2(d), pH, Conductivity, T°), major elements (SO4, NO3) and metals (Fe, Ni, Mn, Co). The acquired data enabled us to identify from one hand, the conditions which are presented within the site, special thanks to the evolution of nitrate and iron contents and on the other hand, the natural origin (geological) of nickel for two of the three sites studied based essentially on the evaluation of the Nickel/Cobalt ratio. Thus, on the first site, the evolution of nickel content and nitrate content showed the influence of the phenomenon of denitrification on the re-mobilisation of the nickel. Whereas on the second site, a high variation of total iron content and oxygen dissolved in solution highlighted a particular phenomenon of oxidation of the pyrite through molecular oxygen. Finally, the correlation with the sulphates clearly showed behaviour of the nickel, once released, that was entirely dependent on the phenomenon of adsorption on the iron and manganese hydroxides.

  12. Phytoplankton, chemical, physical, and other data were collected using bottle, CTD casts, and other instruments in the North Sea as part of the North Sea Project, 15 April 1988 - 30 July 1991 (NODC Accession 9300008)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Phytoplankton, chemical, physical, and other data were collected using bottle, current meter, net, pump, and CTD casts in the North Sea from April 15, 1988 to July...

  13. The transport and behaviour of isoproturon in unsaturated chalk cores

    Science.gov (United States)

    Besien, T. J.; Williams, R. J.; Johnson, A. C.

    2000-04-01

    A batch sorption study, a microcosm degradation study, and two separate column leaching studies were used to investigate the transport and fate of isoproturon in unsaturated chalk. The column leaching studies used undisturbed core material obtained from the field by dry percussion drilling. Each column leaching study used 25 cm long, 10 cm wide unsaturated chalk cores through which a pulse of isoproturon and bromide was eluted. The cores were set-up to simulate conditions in the unsaturated zone of the UK Chalk aquifer by applying a suction of 1 kPa (0.1 m H 2O) to the base of each column, and eluting at a rate corresponding to an average recharge rate through the unsaturated Chalk. A dye tracer indicated that the flow was through the matrix under these conditions. The results from the first column study showed high recovery rates for both isoproturon (73-92%) and bromide (93-96%), and that isoproturon was retarded by a factor of about 1.23 relative to bromide. In the second column study, two of the four columns were eluted with non-sterile groundwater in place of the sterile groundwater used on all other columns, and this study showed high recovery rates for bromide (85-92%) and lower recovery rates for isoproturon (66-79% — sterile groundwater, 48-61% — non-sterile groundwater). The enhanced degradation in the columns eluted with non-sterile groundwater indicated that groundwater microorganisms had increased the degradation rate within these columns. Overall, the reduced isoproturon recovery in the second column study was attributed to increased microbial degradation as a result of the longer study duration (162 vs. 105 days). The breakthrough curves (BTCs) for bromide had a characteristic convection-dispersion shape and were accurately simulated with the minimum of calibration using a simple convection-dispersion model (LEACHP). However, the isoproturon BTCs had an unusual shape and could not be accurately simulated.

  14. Fault zone processes in mechanically layered mudrock and chalk

    Science.gov (United States)

    Ferrill, David A.; Evans, Mark A.; McGinnis, Ronald N.; Morris, Alan P.; Smart, Kevin J.; Wigginton, Sarah S.; Gulliver, Kirk D. H.; Lehrmann, Daniel; de Zoeten, Erich; Sickmann, Zach

    2017-04-01

    A 1.5 km long natural cliff outcrop of nearly horizontal Eagle Ford Formation in south Texas exposes northwest and southeast dipping normal faults with displacements of 0.01-7 m cutting mudrock, chalk, limestone, and volcanic ash. These faults provide analogs for both natural and hydraulically-induced deformation in the productive Eagle Ford Formation - a major unconventional oil and gas reservoir in south Texas, U.S.A. - and other mechanically layered hydrocarbon reservoirs. Fault dips are steep to vertical through chalk and limestone beds, and moderate through mudrock and clay-rich ash, resulting in refracted fault profiles. Steeply dipping fault segments contain rhombohedral calcite veins that cross the fault zone obliquely, parallel to shear segments in mudrock. The vertical dimensions of the calcite veins correspond to the thickness of offset competent beds with which they are contiguous, and the slip parallel dimension is proportional to fault displacement. Failure surface characteristics, including mixed tensile and shear segments, indicate hybrid failure in chalk and limestone, whereas shear failure predominates in mudrock and ash beds - these changes in failure mode contribute to variation in fault dip. Slip on the shear segments caused dilation of the steeper hybrid segments. Tabular sheets of calcite grew by repeated fault slip, dilation, and cementation. Fluid inclusion and stable isotope geochemistry analyses of fault zone cements indicate episodic reactivation at 1.4-4.2 km depths. The results of these analyses document a dramatic bed-scale lithologic control on fault zone architecture that is directly relevant to the development of porosity and permeability anisotropy along faults.

  15. THE POLLUTION OF THE BOTTOM SEDIMENTSIN THE NORTH-WESTERN PART OF THE CASPIAN SEA HYDROCARBONS AND PERSISTENT ORGANIC POLLUTANTS

    Directory of Open Access Journals (Sweden)

    E. V. Ostrovskaya

    2014-01-01

    Full Text Available Aim. The pollution of the bottom sediments in the north-western part of the Caspian sea hydrocarbons and persistent organic pollutants. Location.Caspian Sea. Methods. The materials for this article is based on the results of monitoring conducted in 2012-2013 years. Results. Sediments in the north-western part of the Caspian Sea as a whole slightly contaminated YV and SOZ, although localized areas of high pollution are marked, especially characteristic of the Middle Caspian. Mainconclusions.The studies were showed, PAY in the sediments are mixed genesis, but most of them, in all probability, were petroleum origin. The not weathered hydrocarbons are presented in sediments, which indicates to the presence of the local sources of the fresh oil pollution on the surveyed area.

  16. Modelling Local Sea-Breeze Flow and Associated Dispersion Patterns Over a Coastal Area in North-East Spain: A Case Study

    Science.gov (United States)

    Soler, M. R.; Arasa, R.; Merino, M.; Olid, M.; Ortega, S.

    2011-07-01

    The structure and evolution of the sea breeze in the north-west part of the Mediterranean (Catalonia, north-east Spain) is studied both experimentally and, predominantly, using numerical models to increase understanding of sea-breeze structure and three-dimensional (3D) pollution distributions in coastal environments. Sea-breeze components are modelled and analyzed using the fifth-generation Pennsylvania State University-National Centre for Atmospheric Research Mesoscale Model (MM5). The results show that the growth and structure of the sea-breeze circulation is modulated by the synoptic flow and especially by the complex topography of the area. 3D pollution transport in a sea breeze is modelled by coupling the MM5 to the Community Multiscale Air Quality (CMAQ) model, with results indicating that topography and synoptic flow are the main factors modulating horizontal and vertical pollutant transport in sea-breeze episodes. In this way, horizontal dispersion is limited by the complex topography of the area, whilst the sea-breeze flow is intensified by anabatic upslope winds that contribute to vertical pollutant transport. The numerical model results also indicate that the sea-breeze circulation with a weak return flow at upper levels grows due to a synoptic onshore wind component. However, such a sea-breeze circulation is capable of transporting pollutants towards the coast.

  17. Can we get a better knowledge on dissolution processes in chalk by using microfluidic chips?

    Science.gov (United States)

    Neuville, Amélie; Minde, Mona; Renaud, Louis; Vinningland, Jan Ludvig; Dysthe, Dag Kristian; Hiorth, Aksel

    2017-04-01

    This work has been initiated in the context of research on improving the oil recovery in chalk bedrocks. One of the methods to improve the oil recovery is to inject "smart water" (acidic water/brines). Experiments on core scale and field tests that have been carried out the last decade have clearly shown that water chemistry affects the final oil recovery. However, there is generally no consensus in the scientific community of why additional oil is released, and it is also still not understood what are the mineralogical and structural changes. Direct in situ observation of the structural changes that occur when chalk is flooded with brines could resolve many of the open questions that remain. One of the highlights of this work is thus the development of an innovative methodology where fluid/rock interactions are observed in-situ by microscopy. To do so, we create several types of custom-made microfluidic systems that embeds reactive materials like chalk and calcite. The methodology we develop can be applied to other reactive materials. We will present an experiment where a calcite window dissolves with a fluid, where we observe in-situ the topography features of the calcite window, as well as the dissolution rate [1]. The injected fluid circulates at controlled flowrates in a channel which is obtained by xurography: double sided tape is cut out with a cutter plotter and placed between the reactive window and a non-reactive support. While the calcite window reacts, its topography is measured in situ every 10 s using an interference microscope, with a pixel resolution of 4.9 μm and a vertical resolution of 50 nm. These experiments are also compared with reactive flow simulations done with Lattice Boltzmann methods. Then, we will present a dissolution experiment done with a microfluidic system that embeds chalk. In this experiment, the main flow takes place at the chalk surface, in contact with fluid flowing in a channel above the chalk sample. Thus the reaction

  18. Brief: Refloating Maureen platform for reuse in waters away from the North Sea

    International Nuclear Information System (INIS)

    Tilling, G.M.

    1996-01-01

    The Maureen platform in the U.K. sector of the North Sea is refloatable by virtue of being a steel, gravity-base structure with large oil storage tanks as legs. The fields producing into the Maureen platform will soon be depleted, and plans are to decommission the platform from its present location. The attractive disposal options all involve refloating the platform as a first step. Of these, reuse of the facility is potentially the most attractive. Once afloat, the platform becomes a towable 110,000-tonne vessel available for use in areas of the world away from the North Sea, with location determined by environmental conditions and water depth. The bulk of the weight (92,000 tonnes) is in the jacket structure; topsides weight is 18,000 tonnes. Subject to detailed tow-route and naval-stability calculations, moving the structure long distances appears to be feasible. This paper discusses the refloating and marine stability of the Maureen oil platform as a vessel under tow. Development and maintenance aspects are presented

  19. Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995-2005)

    NARCIS (Netherlands)

    Van Engeland, T.; Soetaert, K.E.R.; Knuijt, A.; Laane, R.W.P.M.; Middelburg, J.J.

    2010-01-01

    Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the

  20. Quantitative 1D saturation profiles on chalk by NMR

    DEFF Research Database (Denmark)

    Olsen, Dan; Topp, Simon; Stensgaard, Anders

    1996-01-01

    Quantitative one-dimensional saturation profiles showing the distribution of water and oil in chalk core samples are calculated from NMR measurements utilizing a 1D CSI spectroscopy pulse sequence. Saturation profiles may be acquired under conditions of fluid flow through the sample. Results reveal...

  1. Certified reference material for radionuclides in fish flesh sample IAEA-414 (mixed fish from the Irish Sea and North Sea)

    DEFF Research Database (Denmark)

    Pham, M.K.; Sanchez-Cabeza, J.A.; Povinec, P.P.

    2006-01-01

    A certified reference material (CRM) for radionuclides in fish sample IAEA-414 (mixed fish from the Irish Sea and North Seas) is described and the results of the certification process are presented. Nine radionuclides (K-40, Cs-137, Th-232, U-234, U-235, U-238, Pu-238, Pu239+240 and Am-241) were...... ratios are also included. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in fish sample, for the development and validation of analytical methods and for training purposes. The material is available from IAEA, Vienna, in 100 g units. (c) 2006 Elsevier Ltd. All...

  2. Spectral Properties of ENVISAT ASAR and QuikSCAT Surface Winds in the North Sea

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Larsén, Xiaoli Guo; Badger, Merete

    2013-01-01

    as an increase in spectral density over similar wavenumber ranges as the spatial resolution increases. The 600-m SAR wind product reveals a range of wavenumbers in which the exchange processes between micro- and meso-scales occur; this range is not captured by the wind products with a resolution of 1.5 km......Spectra derived from ENVISAT Advanced Synthetic Aperture Radar (ASAR) and QuikSCAT near-surface ocean winds are investigated over the North Sea. The two sensors offer a wide range of spatial resolutions, from 600 m to 25 km, with different spatial coverage over the area of interest. This provides...... a unique opportunity to study the impact of the spatial resolution on the spectral properties of the wind over a wide range of length scales. Initially, a sub-domain in the North Sea is chosen, due to the overlap of 87 wind scenes from both sensors. The impact of the spatial resolution is manifested...

  3. Temperature tracking by North Sea benthic invertebrates in response to climate change.

    Science.gov (United States)

    Hiddink, Jan G; Burrows, Michael T; García Molinos, Jorge

    2015-01-01

    Climate change is a major threat to biodiversity and distributions shifts are one of the most significant threats to global warming, but the extent to which these shifts keep pace with a changing climate is yet uncertain. Understanding the factors governing range shifts is crucial for conservation management to anticipate patterns of biodiversity distribution under future anthropogenic climate change. Soft-sediment invertebrates are a key faunal group because of their role in marine biogeochemistry and as a food source for commercial fish species. However, little information exists on their response to climate change. Here, we evaluate changes in the distribution of 65 North Sea benthic invertebrate species between 1986 and 2000 by examining their geographic, bathymetric and thermal niche shifts and test whether species are tracking their thermal niche as defined by minimum, mean or maximum sea bottom (SBT) and surface (SST) temperatures. Temperatures increased in the whole North Sea with many benthic invertebrates showing north-westerly range shifts (leading/trailing edges as well as distribution centroids) and deepening. Nevertheless, distribution shifts for most species (3.8-7.3 km yr(-1) interquantile range) lagged behind shifts in both SBT and SST (mean 8.1 km yr(-1)), resulting in many species experiencing increasing temperatures. The velocity of climate change (VoCC) of mean SST accurately predicted both the direction and magnitude of distribution centroid shifts, while maximum SST did the same for contraction of the trailing edge. The VoCC of SBT was not a good predictor of range shifts. No good predictor of expansions of the leading edge was found. Our results show that invertebrates need to shift at different rates and directions to track the climate velocities of different temperature measures, and are therefore lagging behind most temperature measures. If these species cannot withstand a change in thermal habitat, this could ultimately lead to a drop in

  4. Neogene dinocyst zonation for the eastern North Sea Basin, Denmark

    DEFF Research Database (Denmark)

    Dybkjær, Karen; Piasecki, Stefan

    2010-01-01

    A dinocyst zonation for the Neogene succession in the eastern part of the North Sea Basin (Denmark) is presented. The zonation is based on an extensive database comprising data from more than fifty onshore and offshore boreholes and about twenty five outcrops. Most of the nineteen dinocyst zones......, of the Lower Miocene, and of the Upper Miocene and Pliocene successions. The previous zonation of the onshore Danish Middle Miocene is reconsidered and partly redefined. The zonation is correlated with other biostratigraphic subdivisions of the Neogene succession in the Danish region in addition to litho...

  5. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from HUDSON in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1982-02-28 to 1982-04-04 (NODC Accession 0113889)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0113889 includes chemical, discrete sample, physical and profile data collected from HUDSON in the North Atlantic Ocean, North Greenland Sea and...

  6. Norwegian 1990 sediment data for the North Sea Task Force (NSTF) and the Joint Monitoring Group (JMG)

    Energy Technology Data Exchange (ETDEWEB)

    Green, N.W.; Klungsoeyr, J.

    1994-12-31

    This report presents the 1990 sediment data compiled as part of the Norwegian contribution to the North Sea Task Force Monitoring Master Plan and the Joint Monitoring Programme (JMP). The JMP is ordered under the Oslo and Paris Commissions, which were established to protect the marine environment against anthropogenic contamination. The stations monitored by Norway are spread over the Kattegat, Skagerrak, North Sea south to the Dogger Bank and the Faeroe Islands. The contaminants investigated are mainly selected metals, organochlorines, polycyclic aromatic hydrocarbons, and the samples were collected by gravity cores and grab/box samplers. The raw data and the mean and standard deviations of parallel samples (if relevant) are presented. 6 refs., 2 tabs.

  7. Productivity and recovery of forage fish under climate change and fishing: North Sea sandeel as a case study

    DEFF Research Database (Denmark)

    Lindegren, Martin; van Deurs, Mikael; MacKenzie, Brian

    2018-01-01

    -east Atlantic, acting as a key prey for predatory fish and sea birds, as well as supporting a large commercial fishery. In this case study, we investigate the underlying factors affecting recruitment and how these in turn affect productivity of the North Sea sandeel using long-term data and modelling. Our...... results demonstrate how sandeel productivity in the central North Sea (Dogger Bank) depends on a combination of external and internal regulatory factors, including fishing and climate effects, as well as density dependence and food availability of the preferred zooplankton prey (Calanus finmarchicus...... and Temora longicornis). Furthermore, our model scenarios suggest that while fishing largely contributed to the abrupt stock decline during the late 1990s and the following period of low biomass, a complete recovery of the stock to the highly productive levels of the early 1980s would only be possible...

  8. Distribution of Polycystine Radiolarians in Bottom Surface Sediments and Its Relation to Summer Sea Temperature in the High-Latitude North Atlantic

    Directory of Open Access Journals (Sweden)

    Alexander Matul

    2017-10-01

    Full Text Available An objective of the study is to get new biogeographic information on the modern polycystine radiolarians from the high-latitude North Atlantic. The quantitative radiolarian dataset was compiled from publications and own micropaleontological counts from samples of the bottom surface sediments of the North Atlantic north of 40°N and Nordic Seas. Standard statistical treatment of micropaleontological data by factor analysis reveals five radiolarian assemblages which have their highest load at the specific temperature range in agreement with the oceanographic setting. An occurrence of radiolarian assemblages reflects extension and interaction of the warm North Atlantic and cold Polar/Arctic waters. Radiolarian distribution exhibits good correlation with the climatically averaged summer sea temperature on depth level of 200 m.

  9. Hierarchical modeling of bycatch rates of sea turtles in the western North Atlantic

    Science.gov (United States)

    Gardner, B.; Sullivan, P.J.; Epperly, S.; Morreale, S.J.

    2008-01-01

    Previous studies indicate that the locations of the endangered loggerhead Caretta caretta and critically endangered leatherback Dermochelys coriacea sea turtles are influenced by water temperatures, and that incidental catch rates in the pelagic longline fishery vary by region. We present a Bayesian hierarchical model to examine the effects of environmental variables, including water temperature, on the number of sea turtles captured in the US pelagic longline fishery in the western North Atlantic. The modeling structure is highly flexible, utilizes a Bayesian model selection technique, and is fully implemented in the software program WinBUGS. The number of sea turtles captured is modeled as a zero-inflated Poisson distribution and the model incorporates fixed effects to examine region-specific differences in the parameter estimates. Results indicate that water temperature, region, bottom depth, and target species are all significant predictors of the number of loggerhead sea turtles captured. For leatherback sea turtles, the model with only target species had the most posterior model weight, though a re-parameterization of the model indicates that temperature influences the zero-inflation parameter. The relationship between the number of sea turtles captured and the variables of interest all varied by region. This suggests that management decisions aimed at reducing sea turtle bycatch may be more effective if they are spatially explicit. ?? Inter-Research 2008.

  10. Holocene relative sea-level changes from North America and the Caribbean

    Science.gov (United States)

    Horton, Benjamin; Engelhart, Simon; Vacchi, Matteo; Khan, Nicole; Peltier, Dick; Roy, Keven

    2014-05-01

    Reconstructions of Holocene relative sea level (RSL) are important for identifying the ice equivalent meltwater contribution to sea-level change during deglaciation. Holocene RSL reconstructions from near, intermediate and far field regions enable the assessment of earth and ice parameters of Glacial Isostatic Adjustment (GIA) models. RSL reconstructions provide data for estimating rates of spatially variable and ongoing vertical land motion; a requirement for understanding the variation in modern and late Holocene sea level as recorded by instrumental and proxy records. Here we explain the methodology employed to reconstruct former sea levels, which follows the practice of the International Geoscience Programme (IGCP). We produce sea level index points from the Pacific and Atlantic coasts of North America and the Caribbean. Index points are defined as the most reliable observations of former sea levels. They consist of an estimate of X (age) and Y (the position of former RSL). Where a suite of index points are developed for a locality or region, they describe changes in RSL through time and estimate rates of change. A valid index point must meet the following four criteria; (1) location of the sample is known; (2) the altitude of the sample (and the error associated with measuring that altitude) is known; (3) the indicative meaning (the relationship between the sample and a tide level) is estimated; and (4) the age of the sample, which is commonly radiocarbon dated is calibrated to sidereal years using the latest calibration curves. In total databases have over 2000 sea-level index points from formerly ice covered, uplifting regions of Canada, to the region of forebulge collapse along the subsiding mid-Atlantic and mid-Pacific coastlines of the United States, to the tropical regions of the Caribbean. Recent analyses of these new published databases have led to a further refinement of the most recent of the ICE-NG (VMX) series of global models of GIA. The records

  11. Towards harmonised assessment and classification of "biodiversity status" in the North Sea eco-region

    DEFF Research Database (Denmark)

    Skov, H.; Andersen, Jesper; Vinther, M.

    As one of the milestones in the HARMONY-project a demonstration of the application of the integrative indicator based biodiversity assessment tool (BEAT) was undertaken for the Greater North Sea sub-region across a range of coastal and offshore areas. The first version of the BEAT tool was applie...

  12. Initial field measurements on the Chalk River superconducting cyclotron

    International Nuclear Information System (INIS)

    Ormrod, J.H.; Chan, K.C.; Hill, J.H.

    1980-12-01

    The midplane magnetic field of the Chalk River superconducting cyclotron has been mapped in detail over the full operating range of 2.5 to 5 tesla. The field measuring apparatus is described and results given include measurements of the field stability, reproducibility and harmonic content. (author)

  13. Biogeochemical consequences of vertical and lateral transport of particulate organic matter in the southern North Sea: A multiproxy approach

    NARCIS (Netherlands)

    Le Guitton, M.; Soetaert, K.; Sinninghe Damsté, J.S.; Middelburg, J.J.

    2015-01-01

    Vertical and lateral transports are of importance in continental shelf systems such as the North Sea andplay a major role in the processing of organic matter. We investigated the biogeochemical consequencesof these transports on particulate organic matter at the molecular level in the southern North

  14. A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

    Directory of Open Access Journals (Sweden)

    Saliou eFaye

    2015-09-01

    Full Text Available The climatological seasonal cycle of the sea surface temperature (SST in the north-eastern tropical Atlantic (7-25°N, 26-12°W is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ. The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N, and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm the surface north (south of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.Keywords: SST, upwelling, circulation, heat budget, observations, modeling

  15. Derived concentration factors for caesium-137 in edible species of North Sea fish

    International Nuclear Information System (INIS)

    Steele, A.K.

    1990-01-01

    Concentration factor (CF=Bq kg -1 fillet/Bg kg -1 filtered sea water) values for 137 Cs in fillets of cod (Gadus morhua), haddock (Merlanogrammus aeglefinus), plaice (Pleuronectes platessa) and whiting (Merlangius merlangius), were derived from fish and filtered seawater concentrations. Samples were collected in twelve sampling boxes in the North Sea over an eight-year period - 1978-1985. The range of results with species, between species, and between surveys are discussed. Mean CF values of 92, 58, 39 and 150 were found in cod, haddock, plaice and whiting respectively. These support the International Atomic Energy Authority recommended CF value of 100 for fish in generalised dose assessments. (author)

  16. Organohalogen compounds in deep-sea fishes from the western North Pacific, off-Tohoku, Japan: Contamination status and bioaccumulation profiles

    International Nuclear Information System (INIS)

    Takahashi, Shin; Oshihoi, Tomoko; Ramu, Karri; Isobe, Tomohiko; Ohmori, Koji; Kubodera, Tsunemi; Tanabe, Shinsuke

    2010-01-01

    Twelve species of deep-sea fishes collected in 2005 from the western North Pacific, off-Tohoku, Japan were analyzed for organohalogen compounds. Among the compounds analyzed, concentrations of DDTs and PCBs (up to 23,000 and 12,400 ng/g lipid wt, respectively) were the highest. The present study is the foremost to report the occurrence of brominated flame retardants such as PBDEs and HBCDs in deep-sea organisms from the North Pacific region. Significant positive correlations found between δ 15 N ( per mille ) and PCBs, DDTs and PBDEs suggest the high biomagnification potential of these contaminants in food web. The large variation in δ 13 C ( per mille ) values observed between the species indicate multiple sources of carbon in the food web and specific accumulation of hydrophobic organohalogen compounds in benthic dwelling carnivore species like snubnosed eel. The results obtained in this study highlight the usefulness of deep-sea fishes as sentinel species to monitor the deep-sea environment.

  17. Benthic macrofauna variations and community structure in Cenomanian cyclic chalk-marl from Southerham Grey Pit, SE England

    DEFF Research Database (Denmark)

    Lauridsen, Bodil Wesenberg; Gale, A. S.; Surlyk, Finn

    2009-01-01

    Cenomanian chalk-marl couplets from England represent the 20 ka Milankovitch precession cycle. Fossil communities from both chalk and marl are identified to test if the orbital fluctuations and the associated changes in substrate lithology and climate exerted any control on the benthic macrofauna...

  18. The importance of predator–prey overlap: predicting North Sea cod recovery with a multispecies assessment model

    DEFF Research Database (Denmark)

    Kempf, Alexander; Dingsør, Gjert Endre; Huse, Geir

    2010-01-01

    The overlap between predator and prey is known as a sensitive parameter in multispecies assessment models for fish, and its parameterization is notoriously difficult. Overlap indices were derived from trawl surveys and used to parametrize the North Sea stochastic multispecies model. The effect...... of time-invariant and year- and quarter-specific overlap estimates on the historical (1991–2007) and predicted trophic interactions, as well as the development of predator and prey stocks, was investigated. The focus was set on a general comparison between single-species and multispecies forecasts...... and the sensitivity of the predicted development of North Sea cod for the two types of overlap implementation. The spatial–temporal overlap between cod and its predators increased with increasing temperature, indicating that foodweb processes might reduce the recovery potential of cod during warm periods...

  19. Sea Spray Aerosol Production over the North Atlantic

    Science.gov (United States)

    Bates, T. S.; Quinn, P.

    2017-12-01

    Breaking waves on the ocean surface generate air bubbles that scavenge organic matter from the surrounding seawater. When injected into the atmosphere, these bubbles burst, yielding sea spray aerosol (SSA), a mixture of organic and inorganic compounds with the organic matter enriched relative to seawater. SSA mass is well documented as the dominant component of aerosol light scattering over the remote oceans. The importance of SSA number to marine boundary layer cloud condensation nuclei (CCN) is much less certain. During the Western Atlantic Climate Study cruises (WACS-1 - August 2012 and WACS-2 - May-June 2014) and the North Atlantic Aerosols and Marine Ecosystem Study cruises (NAAMES-1 - November 2015, NAAMES-2 - May 2016, and NAAMES-3 - September 2017), we generated and measured freshly emitted SSA using the Sea Sweep SSA generator. During the 2017 cruise we also generated SSA with a Marine Aerosol Reference Tank (MART). Using the data generated on these 5 cruises and a large database of remote marine boundary layer aerosol measurements we will address three questions during this presentation: 1 - Do phytoplankton ecosystems affect the organic enrichment of freshly emitted SSA?, 2 - Do plankton ecosystems affect the number production flux of SSA?, and 3 - Is SSA a significant source of atmospheric CCN?

  20. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian Sea from 2000-05-27 to 2000-06-20 (NODC Accession 0115683)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115683 includes biological, chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the Barents Sea, North Greenland Sea...

  1. Polonium-210 in mussels and fish from the Baltic-North Sea estuary

    DEFF Research Database (Denmark)

    Dahlgaard, H.

    1996-01-01

    Polonium-210 has been measured in Danish fish meat caught in the North Sea, the Kattegat and the Baltic in 1991-1994. Average values of 0.35, 0.65 and 0.96 Bq Po-210 kg(-1) fresh weight were observed for cod, herring and plaice fillets, respectively. The difference between species is statistically...... in fish and mussels may represent a natural baseline. Copyright (C) 1996 Elsevier Science Ltd....

  2. Acidity of sphagnum and its relation to chalk and mineral salts

    Energy Technology Data Exchange (ETDEWEB)

    Skene, M

    1915-01-01

    In addition to the criticism and elucidation of various other points, the chief conclusions which may be drawn from the preceding pages are: (1) There is a variation in acidity and in sensitiveness to chalk between the different species of sphagnum. (2) There is a correlation between degree of acidity and degree of sensitiveness. (3) The connection between the two is indirect, not direct. (4) The sphagna thrive in acid solutions: the injurious effect of chalk, and of alkalies in general, is due to the substitution of an alkaline for an acid reaction. (5) Mineral solutions are generally physiologically harmless, but may be ecologically harmful. (6) The sphagna do actually utilize in growth bases held absorbed by the acid compounds of the cell-walls.

  3. Observations of copepod feeding and vertical distribution under natural turbulent conditions in the North Sea

    DEFF Research Database (Denmark)

    Visser, Andre; Saito, H.; Saiz, E.

    2001-01-01

    We present results of simultaneous measurements of turbulent- dissipation rate, zooplankton vertical distribution and copepod gut pigments in the northern North Sea. Analysis shows that some, but not all, copepods (by species, sex and stage) exhibit significant dependence on turbulence in respect...

  4. Amino acids and hexosamines as indicators of organic matter degradation state in North Sea sediments

    NARCIS (Netherlands)

    Dauwe, B.; Middelburg, J.J.

    1998-01-01

    Sediment cores from six stations in the eastern North Sea were analyzed for protein amino acids, the nonprotein amino acids beta-alanine and gamma-aminobutyric acid and the hexosamines galactosamine and glucosamine, and bulk parameters (organic carbon, nitrogen, total hydrolyzable amino acids and

  5. Modelling and analysis of offshore energy systems on North Sea oil and gas platforms

    DEFF Research Database (Denmark)

    Nguyen, Tuong-Van; Elmegaard, Brian; Pierobon, Leonardo

    2012-01-01

    export, and power generation. In this paper, a generic model of a North Sea oil and gas platform is described and the most thermodynamically inefficient processes are identified by performing an exergy analysis. Models and simulations are built and run with the tools Aspen Plus R, DNA and Aspen HYSYS R...

  6. Development of north sea coastal plankton communities in separate plastic bags under identical conditions

    NARCIS (Netherlands)

    Kuiper, J.

    1977-01-01

    In two experiments lasting 4 to 6 weeks, communities of North Sea coastal plankton kept in separate plastic bags (of about 1400 l) and exposed to the same environmental conditions showed very similar patterns of growth and decline. This result means that the method is suitable for the evaluation of

  7. Realized habitats of early-stage North Sea herring: looking for signals of environmental change

    DEFF Research Database (Denmark)

    Röckmann, C.; Dickey-Collas, M.; Payne, Mark

    2011-01-01

    Realized habitats of North Sea herring for two larval and two juvenile stages were estimated over the past 30 years, using abundances from surveys tied to modelled estimates of temperature and salinity. Newly hatched larvae (NHL) were found mainly in water masses of 9–11°C, pre-metamorphosis larvae...

  8. Collective behaviour of climate indices in the North Pacific air—sea system and its potential relationships with decadal climate changes

    International Nuclear Information System (INIS)

    Wang Xiao-Juan; Zhi Rong; He Wen-Ping; Gong Zhi-Qiang

    2012-01-01

    A climate network of six climate indices of the North Pacific air—sea system is constructed during the period of 1948–2009. In order to find out the inherent relationship between the intrinsic mechanism of climate index network and the important climate shift, the synchronization behaviour and the coupling behaviour of these indices are investigated. Results indicate that climate network synchronization happened around the beginning of the 1960s, in the middle of the 1970s and at the beginnings of the 1990s and the 2000s separately. These synchronization states were always followed by the decrease of the coupling coefficient. Each synchronization of the network was well associated with the abrupt phase or trend changes of annually accumulated abnormal values of North Pacific sea-surface temperature and 500-hPa height, among which the one that happened in the middle of the 1970s is the most noticeable climate shift. We can also obtain this mysterious shift from the first mode of the empirical orthogonal function of six indices. That is to say, abrupt climate shift in North Pacific air—sea system is not only shown by the phase or trend changes of climate indices, but also might be indicated by the synchronizing and the coupling of climate indices. Furthermore, at the turning point of 1975, there are also abrupt correlation changes in the yearly mode of spatial degree distribution of the sea surface temperature and 500-hPa height in the region of the North Pacific, which further proves the probability of climate index synchronization and coupling shift in air—sea systems. (geophysics, astronomy, and astrophysics)

  9. Collective behaviour of climate indices in the North Pacific air-sea system and its potential relationships with decadal climate changes

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Juan; Zhi Rong; He Wen-Ping; Gong Zhi-Qiang

    2012-01-01

    A climate network of six climate indices of the North Pacific air-sea system is constructed during the period of 1948-2009.In order to find out the inherent relationship between the intrinsic mechanism of climate index network and the important climate shift,the synchronization behaviour and the coupling behaviour of these indices are investigated.Results indicate that climate network synchronization happened around the beginning of the 1960s,in the middle of the 1970s and at the beginnings of the 1990s and the 2000s separately.These synchronization states were always followed by the decrease of the coupling coefficient.Each synchronization of the network was well associated with the abrupt phase or trend changes of annually accumulated abnormal vaiues of North Pacific sea-surface temperature and 500-hPa height,among which the one that happened in the middle of the 1970s is the most noticeable climate shift.We can also obtain this mysterious shift from the first mode of the empirical orthogonal function of six indices.That is to say,abrupt climate shift in North Pacific air-sea system is not only shown by the phase or trend changes of climate indices,but also night be indicated by the synchronizing and the coupling of climate indices.Furthermore,at the turning point of 1975,there are also abrupt correlation changes in the yearly mode of spatial degree distribution of the sea surface temperature and 500-hPa height in the region of the North Pacific,which further proves the probability of climate index synchronization and coupling shift in air-sea systems.

  10. Reservoir fracture mapping using microearthquakes: Austin chalk, Giddings field, TX and 76 field, Clinton Co., KY

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.S.; Rutledge, J.T.; Gardner, T.L. [SPE, Richardson, TX (United States); Fairbanks, T.D.; Miller, M.E.; Schuessler, B.K. [Los Alamos National Lab., NM (United States)

    1996-11-01

    Patterns of microearthquakes detected downhole defined fracture orientation and extent in the Austin chalk, Giddings field, TX and the 76 field, Clinton Co., KY. We collected over 480 and 770 microearthquakes during hydraulic stimulation at two sites in the Austin chalk, and over 3200 during primary production in Clinton Co. Data were of high enough quality that 20%, 31% and 53% of the events could be located, respectively. Reflected waves constrained microearthquakes to the stimulated depths at the base of the Austin chalk. In plan view, microearthquakes defined elongate fracture zones extending from the stimulation wells parallel to the regional fracture trend. However, widths of the stimulated zones differed by a factor of five between the two Austin chalk sites, indicating a large difference in the population of ancillary fractures. Post-stimulation production was much higher from the wider zone. At Clinton Co., microearthquakes defined low-angle, reverse-fault fracture zones above and below a producing zone. Associations with depleted production intervals indicated the mapped fractures had been previously drained. Drilling showed that the fractures currently contain brine. The seismic behavior was consistent with poroelastic models that predicted slight increases in compressive stress above and below the drained volume.

  11. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian Sea from 1999-06-15 to 1999-07-07 (NODC Accession 0115678)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115678 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian...

  12. Aspects of Remote Sensing in the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) Project

    DEFF Research Database (Denmark)

    Hilger, Klaus Baggesen; Nielsen, Allan Aasbjerg; Knudsen, Per

    1999-01-01

    The general objectives of the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) project are presented. These include analyses of the dynamics of the ocean and its characteristics. The analyses are mainly based on remote sensing. As an example a data set obtained by the multi-channel Sea-viewing...... Wide Field-of-view Sensor (SeaWiFs) is analysed. The presentation results include the computed principal components (PC) and the maximum autocorrelation factors (MAF). Both methods are expected to be incorporated into future analyses of the state of the ocean....

  13. Change of MMP dependent on temperature

    DEFF Research Database (Denmark)

    Rudyk, Svetlana Nikolayevna; Søgaard, Erik Gydesen; Akwansa, Eugene

    2008-01-01

       The experiment was conducted with the purpose to investigate how Minimum Miscibility Pressure (MMP) changes at different temperatures. MMP was measured in a high pressure unit. An original oil saturated chalk core plug from the Danish oil field in North Sea was under investigation. The plug...... underestimation of MMP values which can lead to the loss of efficiency of oil extraction....

  14. Chemical composition of aerosol, sea fog, and rainwater in the marine boundary layer of the northwestern North Pacific and its marginal seas

    Science.gov (United States)

    Sasakawa, Motoki; Uematsu, Mitsuo

    2002-12-01

    Samples of aerosol, sea fog, and rainwater were collected during a research cruise in the northwestern North Pacific, the Sea of Okhotsk, and the Sea of Japan in the summer of 1998. High concentrations of NO3-, nss-SO42- and NH4+ in aerosol over the Sea of Japan suggest that anthropogenic substances were transported to this region. Although the Sea of Okhotsk was covered with a clean marine air mass, the concentration of nss-SO42- was comparatively high in the aerosol samples. This nss-SO42- is probably of marine biogenic origin. The pH values of fogwater samples were measured to be fogwater collected over the Sea of Japan were higher than those in the other regions, suggesting that the sea fog scavenged anthropogenic substances. The concentration of nss-SO42- in fogwater over the Sea of Okhotsk was equivalent to that over the Sea of Japan, probably because nss-SO42- and SO2 of marine biogenic origin were scavenged by the sea fog over the Sea of Okhotsk. The pH values of rainwater samples ranged from 6.1 to 7.2 during the cruise, and acidification of the rain was not significant. The concentrations of nss-Ca2+ in the rainwater were higher than those of the fogwater. This suggests that the rain-scavenged continental CaCO3 may have existed above the lower marine boundary layer, where sea fog appeared. Comparisons of the composition of aerosol and fogwater indicated that coarse particles, such as sea salts predominantly act as condensation nuclei of sea fog droplets rather than fine particles such as (NH4)2SO4.

  15. The wind sea and swell waves climate in the Nordic seas

    Science.gov (United States)

    Semedo, Alvaro; Vettor, Roberto; Breivik, Øyvind; Sterl, Andreas; Reistad, Magnar; Soares, Carlos Guedes; Lima, Daniela

    2015-02-01

    A detailed climatology of wind sea and swell waves in the Nordic Seas (North Sea, Norwegian Sea, and Barents Sea), based on the high-resolution reanalysis NORA10, developed by the Norwegian Meteorological Institute, is presented. The higher resolution of the wind forcing fields, and the wave model (10 km in both cases), along with the inclusion of the bottom effect, allowed a better description of the wind sea and swell features, compared to previous global studies. The spatial patterns of the swell-dominated regional wave fields are shown to be different from the open ocean, due to coastal geometry, fetch dimensions, and island sheltering. Nevertheless, swell waves are still more prevalent and carry more energy in the Nordic Seas, with the exception of the North Sea. The influence of the North Atlantic Oscillation on the winter regional wind sea and swell patterns is also presented. The analysis of the decadal trends of wind sea and swell heights during the NORA10 period (1958-2001) shows that the long-term trends of the total significant wave height (SWH) in the Nordic Seas are mostly due to swell and to the wave propagation effect.

  16. The distribution of deep-sea sponge aggregations in the North Atlantic and implications for their effective spatial management

    Science.gov (United States)

    Howell, Kerry-Louise; Piechaud, Nils; Downie, Anna-Leena; Kenny, Andrew

    2016-09-01

    Sponge aggregations have been recognised as key component of shallow benthic ecosystems providing several important functional roles including habitat building and nutrient recycling. Within the deep-sea ecosystem, sponge aggregations may be extensive and available evidence suggests they may also play important functional roles, however data on their ecology, extent and distribution in the North Atlantic is lacking, hampering conservation efforts. In this study, we used Maximum Entropy Modelling and presence data for two deep-sea sponge aggregation types, Pheronema carpenteri aggregations and ostur aggregations dominated by geodid sponges, to address the following questions: 1) What environmental factors drive the broad-scale distribution of these selected sponge grounds? 2) What is the predicted distribution of these grounds in the northern North Atlantic, Norwegian and Barents Sea? 3) How are these sponge grounds distributed between Exclusive Economic Zones (EEZs) and High Seas areas? 4) What percentage of these grounds in High Seas areas are protected by the current High Seas MPA network? Our results suggest that silicate concentration, temperature, depth and amount of particulate organic carbon are the most important drivers of sponge distribution. Most of the sponge grounds are located within national EEZs rather than in the High Seas. Coordinated conservation planning between nations with significant areas of sponge grounds such as Iceland, Greenland and Faroes (Denmark), Norway (coastal Norway and Svalbard), Portugal and the UK, should be implemented in order to effectively manage these communities in view of the increasing level of human activity within the deep-sea environment.

  17. The outlook for investment in the Norwegian North Sea

    International Nuclear Information System (INIS)

    Enger, T.

    1992-01-01

    An outline of the investment potential for oil and gas production on the Norwegian continental shelf is given. The continental shelf includes the Haltenbanken area and the Barents Sea as well as the North Sea. A description of existing projects and present knowledge of future prospects is given. The total production of oil and gas in 1990 was 107 million toe, the ratio of oil to gas production being 4:1. The relationship between oil and gas will change dramatically in the future however as the gas share in fields under development is much greater than in currently producing fields. The greatest potential for gas is expected to be in the Barents Sea which, being located at a considerable distance from existing gas markets presents a great challenge for commercial development. The conclusion drawn from the outline is that the present level of investment will be maintained or increase slightly over the next four to five years. For the period up to the turn of the century there is increasing uncertainty over the investment level which will become more and more dependent upon further expansion of gas exports but a best estimate is for continued investment stability beyond the year 2000. The production level can be expected to increase and reach a peak during the late 1990s. The resource base is sufficient to maintain a high production level for several decades after the year 2000. (UK)

  18. Potential Impacts of Offshore Wind Farms on North Sea Stratification

    Science.gov (United States)

    Carpenter, Jeffrey R.; Merckelbach, Lucas; Callies, Ulrich; Clark, Suzanna; Gaslikova, Lidia; Baschek, Burkard

    2016-01-01

    Advances in offshore wind farm (OWF) technology have recently led to their construction in coastal waters that are deep enough to be seasonally stratified. As tidal currents move past the OWF foundation structures they generate a turbulent wake that will contribute to a mixing of the stratified water column. In this study we show that the mixing generated in this way may have a significant impact on the large-scale stratification of the German Bight region of the North Sea. This region is chosen as the focus of this study since the planning of OWFs is particularly widespread. Using a combination of idealised modelling and in situ measurements, we provide order-of-magnitude estimates of two important time scales that are key to understanding the impacts of OWFs: (i) a mixing time scale, describing how long a complete mixing of the stratification takes, and (ii) an advective time scale, quantifying for how long a water parcel is expected to undergo enhanced wind farm mixing. The results are especially sensitive to both the drag coefficient and type of foundation structure, as well as the evolution of the pycnocline under enhanced mixing conditions—both of which are not well known. With these limitations in mind, the results show that OWFs could impact the large-scale stratification, but only when they occupy extensive shelf regions. They are expected to have very little impact on large-scale stratification at the current capacity in the North Sea, but the impact could be significant in future large-scale development scenarios. PMID:27513754

  19. Model calculations of the effects of present and future emissions of air pollutants from shipping in the Baltic Sea and the North Sea

    Directory of Open Access Journals (Sweden)

    J. E. Jonson

    2015-01-01

    Full Text Available Land-based emissions of air pollutants in Europe have steadily decreased over the past two decades, and this decrease is expected to continue. Within the same time span emissions from shipping have increased in EU ports and in the Baltic Sea and the North Sea, defined as SECAs (sulfur emission control areas, although recently sulfur emissions, and subsequently particle emissions, have decreased. The maximum allowed sulfur content in marine fuels in EU ports is now 0.1%, as required by the European Union sulfur directive. In the SECAs the maximum fuel content of sulfur is currently 1% (the global average is about 2.4%. This will be reduced to 0.1% from 2015, following the new International Maritime Organization (IMO rules. In order to assess the effects of ship emissions in and around the Baltic Sea and the North Sea, regional model calculations with the EMEP air pollution model have been made on a 1/4° longitude × 1/8° latitude resolution, using ship emissions in the Baltic Sea and the North Sea that are based on accurate ship positioning data. The effects on depositions and air pollution and the resulting number of years of life lost (YOLLs have been calculated by comparing model calculations with and without ship emissions in the two sea areas. In 2010 stricter regulations for sulfur emissions were implemented in the two sea areas, reducing the maximum sulfur content allowed in marine fuels from 1.5 to 1%. In addition ships were required to use fuels with 0.1 % sulfur in EU harbours. The calculations have been made with emissions representative of 2009 and 2011, i.e. before and after the implementation of the stricter controls on sulfur emissions from 2010. The calculations with present emissions show that per person, an additional 0.1–0.2 years of life lost is estimated in areas close to the major ship tracks with current emission levels. Comparisons of model calculations with emissions before and after the implementation of stricter

  20. Evolution of marine storminess in the Belgian part of the North Sea

    Directory of Open Access Journals (Sweden)

    D. Van den Eynde

    2012-02-01

    Full Text Available Severe storms have affected European coast lines in the past but knowledge on changes in storminess for the last decades is still sparse. Climate change is assumed to be a main driving factor with the potential to induce changes on the intensity, duration and frequency of powerful marine storms, including a long-term influence on peak wind speeds, surges and waves. It is, therefore, important to investigate whether in the last decades changes in the magnitude of storms, their duration and frequency could be observed. Understanding trends in storminess in the last decades will help to better prepare coastal managers for future events, taking into account potential changes on storm occurrence and magnitude to improve planning of mitigation and adaptation strategies. The purpose of this study was to focus on the evolution of extreme wind conditions, wave height and storm surge levels in the North Sea Region, especially in the Belgian part of the North Sea (BPNS. Based on the analysis performed it is concluded that no clear trend can be observed for the occurrence of significant increasing extreme wind speeds over the BPNS. Furthermore, one can conclude that not enough scientific evidence is available to support scenarios with increased wave height or storminess.

  1. Delineation of tunnel valley across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

    DEFF Research Database (Denmark)

    Andersen, Theis Raaschou; Jørgensen, Flemming; Christensen, Steen

    Buried tunnel valleys are elongated depressions eroded into the substratum during the Pleistocene glaciations. Nine such valleys are mapped on- and offshore in a 300 km2 area located at the Danish North Sea coast. The delineation of the buried valleys is based on an extensive data set consisting......, preferred orientations, and morphology support that three of the tunnel valleys cross the North Sea coastline. It is suggested that the nine valleys were formed during at least six events that occurred through one or more pre-Weichselian glaciations. Key words: Pleistocene valleys, geophysical mapping...

  2. Delineation of tunnel valleys across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

    DEFF Research Database (Denmark)

    Andersen, Theis Raaschou; Jørdensen, Flemming; Christensen, Steen

    Buried tunnel valleys are elongated depressions eroded into the substratum during the Pleistocene glaciations. Nine such valleys are mapped on- and offshore in a 300 km2 area located at the Danish North Sea coast. The delineation of the buried valleys is based on an extensive data set consisting......, preferred orientations, and morphology support that three of the tunnel valleys cross the North Sea coastline. It is suggested that the nine valleys were formed during at least six events that occurred through one or more pre-Weichselian glaciations...

  3. Sea Ice and Hydrographic Variability in the Northwest North Atlantic

    Science.gov (United States)

    Fenty, I. G.; Heimbach, P.; Wunsch, C. I.

    2010-12-01

    Sea ice anomalies in the Northwest North Atlantic's Labrador Sea are of climatic interest because of known and hypothesized feedbacks with hydrographic anomalies, deep convection/mode water formation, and Northern Hemisphere atmospheric patterns. As greenhouse gas concentrations increase, hydrographic anomalies formed in the Arctic Ocean associated with warming will propagate into the Labrador Sea via the Fram Strait/West Greenland Current and the Canadian Archipelago/Baffin Island Current. Therefore, understanding the dynamical response of sea ice in the basin to hydrographic anomalies is essential for the prediction and interpretation of future high-latitude climate change. Historically, efforts to quantify the link between the observed sea ice and hydrographic variability in the region has been limited due to in situ observation paucity and technical challenges associated with synthesizing ocean and sea ice observations with numerical models. To elaborate the relationship between sea ice and ocean variability, we create three one-year (1992-1993, 1996-1997, 2003-2004) three-dimensional time-varying reconstructions of the ocean and sea ice state in Labrador Sea and Baffin Bay. The reconstructions are syntheses of a regional coupled 32 km ocean-sea ice model with a suite of contemporary in situ and satellite hydrographic and ice data using the adjoint method. The model and data are made consistent, in a least-squares sense, by iteratively adjusting several model control variables (e.g., ocean initial and lateral boundary conditions and the atmospheric state) to minimize an uncertainty-weighted model-data misfit cost function. The reconstructions reveal that the ice pack attains a state of quasi-equilibrium in mid-March (the annual sea ice maximum) in which the total ice-covered area reaches a steady state -ice production and dynamical divergence along the coasts balances dynamical convergence and melt along the pack’s seaward edge. Sea ice advected to the

  4. EPXMA survey of shelf sediments (Southern Bight, North Sea): A glance beyond the XRD-invisible

    NARCIS (Netherlands)

    De Maeyer-Worobiec, A.; Dekov, V.M.; Laane, R.W.P.M.; van Grieken, R.

    2009-01-01

    Shelf sediments of the southern North Sea, were studied with a microanalytical [electron probe X-ray microanalysis (EPXMA)] and two bulk [X-ray diffraction (XRD) and X-ray fluorescence (XRF)] techniques. The investigation proved that the promptness of the microanalytical method is combined with a

  5. Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?

    DEFF Research Database (Denmark)

    Rindorf, Anna; Andersen, Bo Sølgaard

    2008-01-01

    This study presents all investigation of the relationship between stock size of North Sea cod (Gadus morhua) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a model allowing both density-dependent changes in catchability and bias...

  6. The south-eastern North Sea : losses of vertebrate fauna during the past 2000 years

    NARCIS (Netherlands)

    Wolff, W.J.

    At least 31 species of marine mammals, marine and coastal birds, and marine and anadromous fish have disappeared temporarily or permanently from the coasts of The Netherlands and in most cases also from the south-eastern North Sea (south of 54 degrees N) during the past 2000 years-In 18-22 cases,

  7. Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, I.; Vialard, J.; Lengaigne, M.; Han, W.; Mc; Durand, F.; Muraleedharan, P.M.

    version: Geophys. Res. Lett., vol.40(21); 2013; 5740-5744 Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide I. Suresh1, J. Vialard2, M. Lengaigne2, W. Han3, J. McCreary4, F. Durand5, P.M. Muraleedharan1... reversing winds. These wind variations drive seasonal equatorial Kelvin and Rossby wave responses. The seasonal equatorial Kelvin waves propagate into the North Indian Ocean (hereafter NIO) as coastal Kelvin waves [McCreary et al., 1993]. As a result...

  8. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 2001-05-27 to 2001-06-19 (NODC Accession 0113754)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113754 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Atlantic Ocean, North Greenland Sea and...

  9. Seismicity of the 24 May 2014 Mw 7.0 Aegean Sea earthquake sequence along the North Aegean Trough

    Science.gov (United States)

    Görgün, Ethem; Görgün, Burçak

    2015-11-01

    The northern Aegean Sea was hit by a large size (Mw = 7.0) earthquake on 2014 May 24. Centroid moment tensor solutions for 40 events with moment magnitudes (Mw) between 3.3 and 7.0 are computed by applying a waveform inversion method on data from the Turkish and Greek broadband seismic networks. The time span of data covers the period between 2014 May 24 and 2014 June 26. The mainshock is a shallow focus strike-slip event at a depth of 15 km. Focal depths of aftershocks range from 6 to 30 km. The seismic moment (Mo) of the mainshock is estimated as 4.60 × 1019 Nm. The calculated rupture duration of the North Aegean Sea mainshock is 40 s. The focal mechanisms of the aftershocks are mainly strike-slip faulting with a minor normal component. The geometry of focal mechanisms reveals a strike-slip faulting regime with NE-SW trending direction of T-axis in the entire activated region. A stress tensor inversion of focal mechanism data is performed to acquire a more accurate picture of the northern Aegean Sea stress field along the North Aegean Trough. The stress tensor inversion results indicate a predominant strike-slip stress regime with a NW-SE oriented maximum principal compressive stress (σ1). In the development of the North Aegean Trough in Aegean Sea is in good agreement with the resolved stress tensors. With respect the newly determined focal mechanisms, the effect of the propagating of the North Anatolian Fault into Aegean Sea is very clearly pronounced. According to high-resolution hypocenter relocation of the North Aegean Sea seismic sequence, three main clusters are revealed. The aftershock activity in the observation period between 2014 May 24 and 2014 July 31 extends from the mainshock cluster from NE to the SW direction. Seismic cross-sections indicate that a complex pattern of the hypocenter distribution with the activation of seventeen segments. The eastern cluster is associated with a fault plane trending mainly ENE-WSW and dipping vertical, while the

  10. Larval growth and drift pattern and the separation of herring spawning groups in the North Sea

    DEFF Research Database (Denmark)

    Munk, Peter; Christensen, Villy

    1990-01-01

    Data from two internationally co-ordinated survey programmes are used in an attempt to display the events in the early life that took place during the 'recovery period' of the North Sea herring stock, 1979-1986. During the period, an increasing importance of the spawning grounds off Buchan and off...... Yorkshire is evident from distributions of newly hatched herring larvae. The dramatic changes in relative importance of spawning grounds are traced in the data on both late larvae (6 months old) and juveniles (18 months old). The onset of extended spawning off Buchan and off Yorkshire was followed...... in the relative contributions from spawning grounds apparently influence the overall spatial distribution as well as size composition of larval and juvenile North Sea herring. The findings indicate that groups of larvae retain, to a large extent, separate distributions until metamorphosis, and point to larval...

  11. Well data summary sheets. Vol. 33: North sea wells

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This 33rd volume of the `Well Data Summary sheets` includes data from seven recently released offshore wells from the North Sea. The wells Baron-2, S.E. Adda-1 and Skjold Flank-1 were presented in our `Well Data Summary Sheets, special volume`, published May 1, 1997. In volume 33, the wells Baron-2 and Skjold Flank-1 are updated with respect to information on sidewall cores. Information regarding all released well data, included in our well data summary sheets, are available on GEUS homepage: http://www.geus.dk/ or the departments homepage: http://www.geus.dk/departments/geol-info-data-centre/geoldata.htm/. A complete index of releases wells in volumes 17-33 is included. (au)

  12. Are white-beaked dolphins Lagenorhynchus albirostris food specialst? Their diet in the southern North Sea

    NARCIS (Netherlands)

    Jansen, O.E.; Leopold, M.F.; Meesters, H.W.G.; Smeenk, C.

    2010-01-01

    The white-beaked dolphin Lagenorhynchus albirostris is the most numerous cetacean after the harbour porpoise Phocoena phocoena in the North Sea, including Dutch coastal waters. In this study, the diet of 45 white-beaked dolphins stranded on the Dutch coast between 1968 and 2005 was determined by

  13. Detection of low numbers of microplastics in North Sea fish using strict quality assurance criteria

    NARCIS (Netherlands)

    Hermsen, E.; Pompe, R.; Besseling, E.; Koelmans, A.A.

    2017-01-01

    We investigated 400 individual fish of four North Sea species: Atlantic Herring, Sprat, Common Dab, and Whiting on ingestion of > 20 μm microplastic. Strict quality assurance criteria were followed in order to control contamination during the study. Two plastic particles were found in only 1 (a

  14. Critical report of current fisheries management measures implemented for the North Sea mixed demersal fisheries

    DEFF Research Database (Denmark)

    Nielsen, J. Rasmus; Ulrich, Clara; Hegland, Troels J.

    The present report is an EU-FP7-SOCIOEC Report giving an overview and critical evaluation of the current management measures implemented for the North Sea mixed demersal fisheries and the fish stocks involved in this. Also, this involves review and critical evaluation of the scientific advice...

  15. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the G.O. SARS in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 2003-09-22 to 2003-10-13 (NODC Accession 0113752)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113752 includes chemical, discrete sample, physical and profile data collected from G.O. SARS in the North Atlantic Ocean, North Greenland Sea and...

  16. Detection of low numbers of microplastics in North Sea fish using strict quality assurance criteria.

    Science.gov (United States)

    Hermsen, Enya; Pompe, Renske; Besseling, Ellen; Koelmans, Albert A

    2017-09-15

    We investigated 400 individual fish of four North Sea species: Atlantic Herring, Sprat, Common Dab, and Whiting on ingestion of >20μm microplastic. Strict quality assurance criteria were followed in order to control contamination during the study. Two plastic particles were found in only 1 (a Sprat) out of 400 individuals (0.25%, with a 95% confidence interval of 0.09-1.1%). The particles were identified to consist of polymethylmethacrylate (PMMA) through FTIR spectroscopy. No contamination occurred during the study, showing the method applied to be suitable for microplastic ingestion studies in biota. We discuss the low particle count for North Sea fish with those in other studies and suggest a relation between reported particle count and degree of quality assurance applied. Microplastic ingestion by fish may be less common than thought initially, with low incidence shown in this study, and other studies adhering to strict quality assurance criteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Postglacial sedimentary regime around northern Sylt, South-eastern North Sea, based on shallow seismic evidence

    DEFF Research Database (Denmark)

    Boldreel, Lars Ole; Kuijpers, Antoon; Madsen, Emil B

    2010-01-01

    , in the outer delta, a dune field suggesting westerly-directed sediment transport is identified. The two dune fields appear to be separated by minor indefinite bed forms. The northern part of the Lister Tief is characterised by the presence of a channel with a depth of 20-30 mbsf (meter below sea level) (30......-40 msec TWT (Two Way Traveltime)) and displaying erosion towards the north. At the western termination of the channel the sediment transport pathway appears to be divided into two directions; one towards the outer delta, and one towards the sediment depocenter SW of Rømø. The Lister Ley is characterized......During the past 5 years the coastal zone offshore the northern part of the island of Sylt, has been investigated by sparker seismics and high-resolution subbottom profiling. The North Sea sector of the area is characterized by northward-directed sediment bypass as a result of strong long...

  18. A multi-decadal wind-wave hindcast for the North Sea 1949-2014: coastDat2

    Science.gov (United States)

    Groll, Nikolaus; Weisse, Ralf

    2017-12-01

    Long and consistent wave data are important for analysing wave climate variability and change. Moreover, such wave data are also needed in coastal and offshore design and for addressing safety-related issues at sea. Using the third-generation spectral wave model WAM a multi-decadal wind-wave hindcast for the North Sea covering the period 1949-2014 was produced. The hindcast is part of the coastDat database representing a consistent and homogeneous met-ocean data set. It is shown that despite not being perfect, data from the wave hindcast are generally suitable for wave climate analysis. In particular, comparisons of hindcast data with in situ and satellite observations show on average a reasonable agreement, while a tendency towards overestimation of the highest waves could be inferred. Despite these limitations, the wave hindcast still provides useful data for assessing wave climate variability and change as well as for risk analysis, in particular when conservative estimates are needed. Hindcast data are stored at the World Data Center for Climate (WDCC) and can be freely accessed using the doi:10.1594/WDCC/coastDat-2_WAM-North_Sea Groll and Weisse(2016) or via the coastDat web-page http://www.coastdat.de.

  19. A sedimentological approach to refining reservoir architecture in a mature hydrocarbon province: the Brent Province, UK North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Hampson, G.J.; Sixsmith, P.J.; Johnson, H.D. [Imperial College, London (United Kingdom). Dept. of Earth Science and Engineering

    2004-04-01

    Improved reservoir characterisation in the mature Brent Province of the North Sea, aimed at maximising both in-field and near-field hydrocarbon potential, requires a clearer understanding of sub-seismic stratigraphy and facies distributions. In this context, we present a regional, high-resolution sequence stratigraphic framework for the Brent Group, UK North Sea based on extensive sedimentological re-interpretation of core and wireline-log data, combined with palynostratigraphy and published literature. This framework is used to place individual reservoirs in an appropriate regional context, thus resulting in the identification of subtle sedimentological and tectono-stratigraphic features of reservoir architecture that have been previously overlooked. We emphasise the following insights gained from our regional, high-resolution sequence stratigraphic synthesis: (1) improved definition of temporal and spatial trends in deposition both within and between individual reservoirs, (2) development of regionally consistent, predictive sedimentological models for two enigmatic reservoir intervals (the Broom and Tarbert Formations), and (3) recognition of subtle local tectono-stratigraphic controls on reservoir architecture, and their links to the regional, Middle Jurassic structural evolution of the northern North Sea. We discuss the potential applications of these insights to the identification of additional exploration potential and to improved ultimate recovery. (author)

  20. Changes in distributional patterns of plaice Pleuronectes platessa in the central and eastern North Sea; do declining nutrient loadings play a role?

    DEFF Research Database (Denmark)

    Støttrup, Josianne Gatt; Munk, Peter; Kodama, Masashi

    2017-01-01

    of offshore habitats as nursery areas by juvenile plaice in the North Sea appears not related to water depth per se but driven by specific processes dominating in near-shore areas and may be related to changes in nutrient loadings. This point to the importance of separating more general depth-related factors....... For the same time period available time series data on nutrient conditions in the coastalNorth Sea area showthat the freshwater nitrogen loading has decreased by about 50%. While nutrient concentrations in the ambient environment have been shown to influence growth in juvenile plaice through influence...... on their prey, we here inspect the potential linkage between distributional changes in plaice and the decline in nutrient loading.We compare plaice observations in coastal areas in the eastern North Sea,which have experienced large changes in eutrophication,with observations for the Dogger Bank, a large...

  1. Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations

    OpenAIRE

    Pätsch, Johannes; Kühn, Wilfried; Six, Katharina D.

    2018-01-01

    For the sediments of the central and southern North Sea different sources of alkalinity generation are quantified by a regional modelling system for the period 2000–2014. For this purpose a formerly global ocean sediment model coupled with a pelagic ecosystem model is adopted to shelf sea dynamics where much larger turnover rates than in the open and deep ocean occurs. To track alkalinity changes due to different nitrogen-related processes the open ocean sediment model was extended by t...

  2. Changes in distributional patterns of plaice Pleuronectes platessa in the central and eastern North Sea; do declining nutrient loadings play a role?

    Science.gov (United States)

    Støttrup, Josianne G.; Munk, Peter; Kodama, Masashi; Stedmon, Colin

    2017-09-01

    Since the beginning of the 1990s, there has been a change in the relative distribution of smaller age-classes of plaice Pleuronectes platessa (age 1-3) in the North Sea. The abundances have increased in deeper, more offshore areas, while coastal abundances have been stagnant or declining. For the same time period available time series data on nutrient conditions in the coastal North Sea area show that the freshwater nitrogen loading has decreased by about 50%. While nutrient concentrations in the ambient environment have been shown to influence growth in juvenile plaice through influence on their prey, we here inspect the potential linkage between distributional changes in plaice and the decline in nutrient loading. We compare plaice observations in coastal areas in the eastern North Sea, which have experienced large changes in eutrophication, with observations for the Dogger Bank, a large sandbank in a shallow offshore area of the North Sea. The Dogger Bank, was used as a reference location assuming this area has been less influenced from coastal eutrophication but similar regional climate conditions, and here we found no changes in the abundances of juvenile plaice. The increase in the use of offshore habitats as nursery areas by juvenile plaice in the North Sea appears not related to water depth per se but driven by specific processes dominating in near-shore areas and may be related to changes in nutrient loadings. This point to the importance of separating more general depth-related factors from conditions specific for near-shore areas, such as nutrient loadings in coastal waters and export offshore. The concurrent changes in environment and in distribution of juvenile plaice may have implications for environmental and fisheries management.

  3. Circulation and hydrological characteristics of the North Aegean Sea: a contribution from real-time buoy measurements

    Directory of Open Access Journals (Sweden)

    K. NITTIS

    2002-06-01

    Full Text Available In the framework of the POSEIDON Project, a network of open sea oceanographic buoys equipped with meteorological and oceanographic sensors has been operational in the Aegean Sea since 1998. The analysis of upper-ocean physical data (currents at 3m, temperature and salinity at 3-40m depths collected during the last 2 years from the stations of the North Aegean basin indicates a strong temporal variability of flow field and hydrological characteristics in both synoptic and seasonal time scales. The northern part of the basin is mainly influenced by the Black Sea Water outflow and the mesoscale variability of the corresponding thermohaline fronts, while the southern stations are influenced by the general circulation of the Aegean Sea with strong modulations caused by the seasonally varying atmospheric forcing.

  4. Effects of ocean acidification on primary production in a coastal North Sea phytoplankton community

    NARCIS (Netherlands)

    Eberlein, Tim; Wohlrab, Sylke; Rost, Björn; John, Uwe; Bach, Lennart T.; Riebesell, U.; Van de Waal, D.B.

    2017-01-01

    We studied the effect of ocean acidification (OA) on a coastal North Sea plankton community in a long-term mesocosm CO2-enrichment experiment (BIOACID II long-term mesocosm study). From March to July 2013, 10 mesocosms of 19 m length with a volume of 47.5 to 55.9 m3 were deployed in the Gullmar

  5. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from KNORR in the North Atlantic Ocean, North Greenland Sea and others from 1972-07-18 to 1973-04-01 (NCEI Accession 0143398)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143398 includes discrete sample and profile data collected from KNORR in the North Atlantic Ocean, North Greenland Sea, Norwegian Sea, South Atlantic...

  6. Mapping the spawning grounds of North Sea cod ( Gadus morhua ) by direct and indirect means

    DEFF Research Database (Denmark)

    Fox, C.J.; Taylor, M.; Dickey-Collas, M.

    2008-01-01

    Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey...

  7. Mapping the spawning grounds of North Sea cod (Gadus morhua) by direct and indirect means

    NARCIS (Netherlands)

    Fox, C.J.; Taylor, M.; Dickey-Collas, M.; Fossum, P.; Kraus, G.; Rohlf, N.; Damme, van C.J.G.; Bolle, L.J.

    2008-01-01

    Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey

  8. Decline of the North Sea houting: protective measures for an endangered anadromous fish

    DEFF Research Database (Denmark)

    Jepsen, Niels; Deacon, Michael; Koed, Anders

    2012-01-01

    Once an abundant fish species in the rivers of the Wadden Sea in northwest Europe, the North Sea houting Coregonus oxyrinchus (NSH) was at the brink of extinction 25 yr ago. The very last stronghold for this species was in the small Danish River Vidaa. In an attempt to preserve this anadromous...... whitefish species, juveniles were hatchery-reared and stocked in 6 Danish rivers flowing into the Wadden Sea. These stocking efforts were fairly successful, and the houting established populations in at least 2 of the rivers, but the underlying problem of habitat degradation and migration obstacles...... they reach sexual maturity, NSH grow relatively slowly (mean: 2.55 cm yr−1, ranging from 0 to 13.8 cm yr−1) and can reach an age of 10 to 12 yr. The number of repeated recaptures year after year indicates low mortality for adult fish. Six individuals were recaptured in rivers other than the one in which...

  9. Wettability of Chalk and Argillaceous Sandstones Assessed from T1/T2 Ratio

    DEFF Research Database (Denmark)

    Katika, Konstantina; Saidian, M.; Fabricius, Ida Lykke

    ratio can quantify the affinity between the rock and wetting pore fluid. The affinity is a measure directly linked to wettability. In order to investigate the T2-shortening, we performed T1-T2 NMR experiments on different samples of chalk, Berea sandstone, and chloritic greensand, saturated either...... with water, oil or oil/water at irreducible water saturation. The T1/T2 ratio obtained from T1-T2 maps reflects the T2-shortening. We compare the T1/T2 ratio for the same type of rock, saturated with different fluids. The chalk shows high affinity for water, Berea sandstone has no clear preference for oil...

  10. Sea surface temperature variability in the North Western Mediterranean Sea (Gulf of Lion) during the Common Era

    Science.gov (United States)

    Sicre, Marie-Alexandrine; Jalali, Bassem; Martrat, Belen; Schmidt, Sabine; Bassetti, Maria-Angela; Kallel, Nejib

    2016-12-01

    This study investigates the multidecadal-scale variability of sea surface temperatures (SSTs) in the convection region of the Gulf of Lion (NW Mediterranean Sea) over the full past 2000 yr (Common Era) using alkenone biomarkers. Our data show colder SSTs by 1.7 °C over most of the first millennium (200-800 AD) and by 1.3 °C during the Little Ice Age (LIA; 1400-1850 AD) than the 20th century mean (17.9 °C). Although on average warmer, those of the Medieval Climate Anomaly (MCA) (1000-1200 AD) were lower by 1 °C. We found a mean SST warming of 2 °C/100 yr over the last century in close agreement with the 0.22 and 0.26 °C/decade values calculated for the western Mediterranean Sea from in situ and satellite data, respectively. Our results also reveal strongly fluctuating SSTs characterized by cold extremes followed by abrupt warming during the LIA. We suggest that the coldest decades of the LIA were likely caused by prevailing negative EA states and associated anticyclone blocking over the North Atlantic resulting in cold continental northeasterly winds to blow over Western Europe and the Mediterranean region.

  11. Long-term temporal and spatial changes in the richness and relative abundance of the inshore fish community of the British North Sea Coast

    Science.gov (United States)

    Henderson, Peter A.

    2017-09-01

    Changes in temporal and spatial composition of the British inshore North Sea fish community are reviewed. Sampling from the cooling water filter screens of power stations bordering the North Sea commenced in the early 1960s. To date, a total of 112 marine fish species have been recorded, a high proportion of the total inshore fish species complement of shallow North Sea British waters. The unrecorded top predators, such as large sharks, swordfish and tuna are not regularly observed in waters fish diversity and abundance in large industrialised estuaries such as the Thames and the Firth of Forth. Linked to spawning and nursery habitat gain, smelt, Osmerus eperlangus, and bass, Dicentrarchus labrax, have greatly increased in abundance. There is no evidence for a decline in species richness since the 1970s. However, elasmobranch species number has declined while two species Raja clavata and Scyliorhinus canicula have remained abundant and one, Mustelus asterias, has increased in abundance. It is argued that overexploitation and habitat destruction remain, as they have been for the last 300 years, the most serious threats to the health of North Sea inshore fish communities. There are no clear signs that climate change is causing species loss, although it may be influencing relative species abundance as species at the southern edge of their range such as the viviparous blenny, Zoarces viviparous, have declined in the southern British North Sea. Power station water temperature records do not show a warming trend, in some estuarine locations temperature has declined with reduced thermal pollution; the temperature record cannot explain the observed major changes in fish relative abundance observed since the 1970s.

  12. The North Sea oil and gas industry and the environment

    International Nuclear Information System (INIS)

    Kingston, P.F.

    1992-01-01

    The North Sea environment is described. Inputs into this environment from oil and gas installations are relatively modest compared with the pollution from effluent discharged or directly dumped into the sea by its highly populated and industrialized enclosing nations. Hydrocarbon discharges provide the greatest input from the oil and gas industry and make a substantial contribution to the total hydrocarbon input. The sources from offshore installations are analysed. Accidental spills, flaring, atmospheric emissions and other inputs are discussed. Biological and chemical monitoring over many year has shown that the most common environmental effect is a marked fall in the number of species of marine fauna and an increase in the number of individuals. These effects appear within 1000 metres of the installation. The spread of contaminants may be more widespread than the biological response indicates, though. The cost of environmental protection is briefly considered. A need to determined the wider impact of low levels of contamination detected at greater distances from platform activities and the development of effective environmental management plans are identified as two objectives for the future. (UK)

  13. The Use of the Lead and Line by Early Navigators in the North Sea?

    Directory of Open Access Journals (Sweden)

    John Kemp

    2014-12-01

    Full Text Available This paper draws attention to the lack of information as to how early North Sea sailors navigated, particularly during the one thousand year period that followed Roman times. The lead and line was the only navigational aid available for most of this period, but there is little recorded as to whether it was used simply for ensuring a ship or boat had enough water to proceed or whether, together with the knowledge it provided of the nature of the sea bed, it was used as a more positive position fixing device. The author would appreciate any information relating to navigation techniques used during this period.

  14. Denali Ice Core Record of North Pacific Sea Surface Temperatures and Marine Primary Productivity

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Kreutz, K. J.; Winski, D.; Wake, C. P.; Ferris, D. G.; Introne, D.; Campbell, S. W.

    2016-12-01

    Chemical analyses of precipitation preserved in glacial ice cores provide a unique opportunity to study changes in atmospheric circulation patterns and ocean surface conditions through time. In this study, we aim to investigate changes in both the physical and biological parameters of the north-central Pacific Ocean and Bering Sea over the twentieth century using the deuterium excess (d-excess) and methanesulfonic acid (MSA) records from the Mt. Hunter ice cores drilled in Denali National Park, Alaska. These parallel, 208 m-long ice cores were drilled to bedrock during the 2013 field season on the Mt. Hunter plateau (63° N, 151° W, 3,900 m above sea level) by a collaborative research team consisting of members from Dartmouth College and the Universities of Maine and New Hampshire. The cores were sampled on a continuous melter system at Dartmouth College and analyzed for the concentrations major ions (Dionex IC) and trace metals (Element2 ICPMS), and for stable water isotope ratios (Picarro). The depth-age scale has been accurately dated to 400 AD using annual layer counting of several chemical species and further validated using known historical volcanic eruptions and the Cesium-137 spike associated with nuclear weapons testing in 1963. We use HYSPLIT back trajectory modeling to identify likely source areas of moisture and aerosol MSA being transported to the core site. Satellite imagery allows for a direct comparison between chlorophyll a concentrations in these source areas and MSA concentrations in the core record. Preliminary analysis of chlorophyll a and MSA concentrations, both derived almost exclusively from marine biota, suggest that the Mt. Hunter ice cores reflect changes in North Pacific and Bering Sea marine primary productivity. Analysis of the water isotope and MSA data in conjunction with climate reanalysis products shows significant correlations (psea surface temperatures in the Bering Sea and North Central Pacific. These findings, coupled with

  15. Fishing effects in northeast Atlantic shelf seas : patterns in fishing effort, diversity and community structure. III. International trawling effort in the North Sea : an analysis of spatial and temporal trends

    DEFF Research Database (Denmark)

    Jennings, S.; Alsväg, J.; Cotter, A.J.R.

    1999-01-01

    of beam trawling effort increases from north to south. Plots of annual fishing effort by ICES statistical rectangle (211 boxes of 0.5 degrees latitude x 1 degrees longitude) indicate that the majority of fishing effort in the North Sea are concentrated in a very few rectangles. Thus mean annual total...

  16. The environmental impact and recovery at two dumping sites for dredged material in the North Sea

    NARCIS (Netherlands)

    Stronkhorst, J.; Ariese, F.; Hattum, van B.; Postma, J.F.; Kluijver, de M.; Besten, den P.; Bergman, M.J.N.; Daan, R.; Murk, A.J.; Vethaak, A.D.

    2003-01-01

    The environmental impact and recovery associated with the long and uninterrupted disposal of large volumes of moderately contaminated dredged material from the port of Rotterdam was studied at nearby dumping sites in the North Sea. Observations were made on sediment contamination, ecotoxicity,

  17. Effect of fluid-solid friction on the stiffness of chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Nguh Akam, Hosea; Fabricius, Ida Lykke

    2011-01-01

    Chalks behave weaker at water saturated condition. We studied this softening effect as a function of Biot’s frequency ratio, which is a ratio between measured ultrasonic wave frequency and Biot critical frequency, fc. Kinematic viscosity of fluid and permeability of rock determines fc. We observe...

  18. North Sea oil taxation in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, A G; Crichton, D

    1979-01-01

    The Norwegian government has developed a complex fiscal regime since 1963 to cover the activities of oil companies in the North Sea. The purpose of this article is to identify and quantify the financial effects of the fiscal system on operating companies involved in the Norwegian sector. The emphasis is on the effect of the tax package introduced by the government in the Odelsting Proposition No. 26 of February 1975. The impact of the tax is not found to be well related to the profitability of fields and the sensitivity of the tax burden to key variables such as reserves, oil price, capital and operating costs and inflation is examined. The most promising change appears to be a discriminatory refund or remission of royalty payments to marginal fields. The Act's main innovation, Special Tax, fails to discriminate between fields of profitability and could influence development decisions in marginal fields. The special allowance provision, by reducing the real cost of capital expenditure and favoring capital-intensive operations, could influence the techniques of exploitation. The effect of quasi-fiscal measures, particularly of government participation via Statoil, is also examined. 10 references.

  19. Observation and analysis of tidal and residual current in the North Yellow Sea in the spring

    Science.gov (United States)

    Miao, Qingsheng; Yang, Jinkun; Yang, Yang; Wan, Fangfang; Yu, Jia

    2018-02-01

    In order to study the current characteristics of the North Yellow Sea (NYS), 4 moored ADCPs (Acoustic Doppler Current Profilers) were deployed and Current characteristics were analyzed based on the observations. Results show that tidal current is the dominant and M2 is the main constituent. Shallow water constituents are obvious in the near-shore area, and tidal current ellipses directions have relations with topography. Residual currents in the Bohai Strait point to the Bohai Sea interior and the magnitude have a connection with terrain. Residual current in south NYS can be divided into two layers, and energy of residual current only accounts for about 13% of the total energy. Barotropic eddy kinetic energy plays a major role and the average in NYS accounts for 87%, baroclinic mean kinetic energy is larger in north NYS, in other regions barotropic mean kinetic energy take the leading position.

  20. Assessments of the lesser sandeel ( Ammodytes marinus ) in the North Sea based on revised stock divisions

    DEFF Research Database (Denmark)

    Pedersen, S.A.; Lewy, Peter; Wright, P.

    1999-01-01

    effort, catch per unit effort, yield, fishing and natural mortality. A better understanding of sandeel growth is important for stock and catch predictions because previous studies indicate that the variability of mean weight-at-age is one of the most important factors influencing the precision......Recent investigations suggest that the current treatment of North Sea sandeel (Ammodytes marinus) as a single unit stock may have little biological basis. In order to study regional effects of the fishery on North Sea lesser sandeel it may therefore be important to assess stock dynamics...... of predictions. The Danish weight-at-age data of sandeel are re- analysed to estimate the mean weight-at-age in the catch and the stock and the precision of the estimates. The reliability of the sandeel assessments is discussed in relation to the data sources available and to the knowledge of sandeel biology...

  1. Land-sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

    Science.gov (United States)

    Donders, Timme H.; van Helmond, Niels A. G. M.; Verreussel, Roel; Munsterman, Dirk; ten Veen, Johan; Speijer, Robert P.; Weijers, Johan W. H.; Sangiorgi, Francesca; Peterse, Francien; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.; Lourens, Lucas; Kuhlmann, Gesa; Brinkhuis, Henk

    2018-03-01

    We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (˜ 2.6-1.8 Ma) multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of Northern Hemisphere glaciation (NHG) in NW Europe, providing the first well-constrained stratigraphic sequence of the classic terrestrial Praetiglian stage. Terrestrial signals were derived from the Eridanos paleoriver, a major fluvial system that contributed a large amount of freshwater to the northeast Atlantic. Due to its latitudinal position, the Eridanos catchment was likely affected by early Pleistocene NHG, leading to intermittent shutdown and reactivation of river flow and sediment transport. Here we apply organic geochemistry, palynology, carbonate isotope geochemistry, and seismostratigraphy to document both vegetation changes in the Eridanos catchment and regional surface water conditions and relate them to early Pleistocene glacial-interglacial cycles and relative sea level changes. Paleomagnetic and palynological data provide a solid integrated timeframe that ties the obliquity cycles, expressed in the borehole geophysical logs, to Marine Isotope Stages (MIS) 103 to 92, independently confirmed by a local benthic oxygen isotope record. Marine and terrestrial palynological and organic geochemical records provide high-resolution reconstructions of relative terrestrial and sea surface temperature (TT and SST), vegetation, relative sea level, and coastal influence.During the prominent cold stages MIS 98 and 96, as well as 94, the record indicates increased non-arboreal vegetation, low SST and TT, and low relative sea level. During the warm stages MIS 99, 97, and 95 we infer increased stratification of the water column together with a higher percentage of arboreal vegetation, high SST, and relative sea level maxima. The early Pleistocene distinct warm-cold alterations are

  2. TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

    Directory of Open Access Journals (Sweden)

    P. Sakov

    2012-08-01

    Full Text Available We present a detailed description of TOPAZ4, the latest version of TOPAZ – a coupled ocean-sea ice data assimilation system for the North Atlantic Ocean and Arctic. It is the only operational, large-scale ocean data assimilation system that uses the ensemble Kalman filter. This means that TOPAZ features a time-evolving, state-dependent estimate of the state error covariance. Based on results from the pilot MyOcean reanalysis for 2003–2008, we demonstrate that TOPAZ4 produces a realistic estimate of the ocean circulation in the North Atlantic and the sea-ice variability in the Arctic. We find that the ensemble spread for temperature and sea-level remains fairly constant throughout the reanalysis demonstrating that the data assimilation system is robust to ensemble collapse. Moreover, the ensemble spread for ice concentration is well correlated with the actual errors. This indicates that the ensemble statistics provide reliable state-dependent error estimates – a feature that is unique to ensemble-based data assimilation systems. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when in-situ profiles below the ice in the Arctic Ocean are assimilated. We find that data assimilation improves the match to independent observations compared to a free model. Improvements are particularly noticeable for ice thickness, salinity in the Arctic, and temperature in the Fram Strait, but not for transport estimates or underwater temperature. At the same time, the pilot reanalysis has revealed several flaws in the system that have degraded its performance. Finally, we show that a simple bias estimation scheme can effectively detect the seasonal or constant bias in temperature and sea-level.

  3. Capillary fringe and tritium and nitrogen tracing history in the Senonian chalk of Champagne

    International Nuclear Information System (INIS)

    Ballif, J.L.

    1998-01-01

    In the middle of Champagne-Ardenne area, a chalky zone is located, directly on top of which lies the soil and in which the water table is relatively close the soil; which allows for capillary direction to the surface horizons and the renewal of water reserve. After the presentation of the hydrological characteristics, the total porosity of chalk, the pores distribution, the capillary attraction is shown by the hydrological comportment of the soil and the upper part of the unsaturated zone of chalk. In the homogeneous rock, the tritium and nitrogen transfers reveal the historical tracks. (authors)

  4. Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

    DEFF Research Database (Denmark)

    van der Molen, J.; van Beek, J.; Augustine, Starrlight

    2015-01-01

    Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coup...

  5. Density and viscosity behavior of a North Sea crude oil, natural gas liquid, and their mixtures

    DEFF Research Database (Denmark)

    Schmidt, KAG; Cisneros, Sergio; Kvamme, B

    2005-01-01

    to accurately model the saturation pressures, densities, and viscosities of petroleum systems ranging from natural gases to heavy crude oils. The applicability of this overall modeling technique to reproduce measured bubble points, densities, and viscosities of a North Sea crude oil, a natural gas liquid...

  6. The atmospheric boundary layer over land and sea: Focus on the off-shore Southern Baltic and Southern North Sea region

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling

    Lecture notes for a short course on the ideal atmospheric boundary layer and its characteristics for different types of real boundary layers, aiming at a discussion of the coastal conditions at the Southern Baltic and North Sea region. The notes are aimed at young scientists (e.g. PhD students......) that study the physics of the atmospheric boundary layer with the purpose of applying this knowledge for remote sensing techniques within offshore wind energy....

  7. Geologic feasibility of selected chalk-bearing sequences within the conterminous United States with regard to siting of radioactive-waste repositories

    International Nuclear Information System (INIS)

    Gonzales, S.

    1975-11-01

    Various geologic and hydrologic parameters are evaluated in relation to assessing the potential for repository storage of high-level radioactive wastes within several stratigraphic sequences dominated by chalks and chalky limestones. The former lithology is defined as a carbonate rock consisting mainly of very fine-grained particles of micritic calcite. Although chalks also contain coarser-grained particles such as shells of fossil foraminifera and non-calcitic minerals like quartz, most contain more than 90 percent micritic material. The latter represents broken fossil coccolith plates. The chalk-dominated formations discussed are exposed and underlie two different physiographic provinces which nevertheless display a general similarity in both being regions of extensive plains. The Niobrara Formation occurs mainly within the Great Plains province, while the Austin Chalk of Texas and the Selma Group of Alabama and Mississippi are located in the western and eastern Gulf Coastal Plain, respectively. The preliminary assessment is that chalk-bearing sequences show some promise and are deserving of added consideration and evaluation. Containment for hundreds of thousands of years would seem possible given certain assumptions. The most promising units from the three studied are the Niobrara Formation and Selma Group. Regional and local conditions make the Austin more suspect

  8. Long-term retrospective analysis of mackerel spawning in the North Sea: a new time series and modeling approach to CPR data.

    Science.gov (United States)

    Jansen, Teunis; Kristensen, Kasper; Payne, Mark; Edwards, Martin; Schrum, Corinna; Pitois, Sophie

    2012-01-01

    We present a unique view of mackerel (Scomber scombrus) in the North Sea based on a new time series of larvae caught by the Continuous Plankton Recorder (CPR) survey from 1948-2005, covering the period both before and after the collapse of the North Sea stock. Hydrographic backtrack modelling suggested that the effect of advection is very limited between spawning and larvae capture in the CPR survey. Using a statistical technique not previously applied to CPR data, we then generated a larval index that accounts for both catchability as well as spatial and temporal autocorrelation. The resulting time series documents the significant decrease of spawning from before 1970 to recent depleted levels. Spatial distributions of the larvae, and thus the spawning area, showed a shift from early to recent decades, suggesting that the central North Sea is no longer as important as the areas further west and south. These results provide a consistent and unique perspective on the dynamics of mackerel in this region and can potentially resolve many of the unresolved questions about this stock.

  9. Long-term retrospective analysis of mackerel spawning in the North Sea: a new time series and modeling approach to CPR data.

    Directory of Open Access Journals (Sweden)

    Teunis Jansen

    Full Text Available We present a unique view of mackerel (Scomber scombrus in the North Sea based on a new time series of larvae caught by the Continuous Plankton Recorder (CPR survey from 1948-2005, covering the period both before and after the collapse of the North Sea stock. Hydrographic backtrack modelling suggested that the effect of advection is very limited between spawning and larvae capture in the CPR survey. Using a statistical technique not previously applied to CPR data, we then generated a larval index that accounts for both catchability as well as spatial and temporal autocorrelation. The resulting time series documents the significant decrease of spawning from before 1970 to recent depleted levels. Spatial distributions of the larvae, and thus the spawning area, showed a shift from early to recent decades, suggesting that the central North Sea is no longer as important as the areas further west and south. These results provide a consistent and unique perspective on the dynamics of mackerel in this region and can potentially resolve many of the unresolved questions about this stock.

  10. Bio-optical characterization in an ultra-oligotrophic region: the North central Red Sea

    KAUST Repository

    Kheireddine, Malika

    2015-04-01

    Until recently, satellite-derived ocean color observations have been the only means of evaluating optical variability of the Red Sea. During a cruise in autumn 2014, we investigated the variability of Inherent Optical Properties (IOPs) in the North Central Red Sea (NCRS) with a particular focus on the particulate backscattering coefficient, bbp, and colored dissolved organic matter, CDOM, absorption. To our knowledge, these are some of the measurements of these properties in the Red Sea. The IOPs are derived from the concentration and physical properties of suspended particles in the ocean. They provide a simple description of the influence of these particles on the light within the water column. Bio-optical relationships found for ultra-oligotrophic waters of the six stations sampled significantly depart from the mean standard relationships provided for the global ocean, showing the peculiar character of the Red Sea. These optical anomalies relate to the specific biological and environmental conditions occurring in the Red Sea ecosystem. Specifically, the surface specific phytoplankton absorption coefficients are lower than the values predicted from the global relationships due to a high proportion of relatively large sized phytoplankton. Conversely, bbp values are much higher than the mean standard values for a given chlorophyll-a concentration, Chl a. This presumably results from the influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column.

  11. Temperature, salinity, oxygen and nutrients bottle and CTD data collected in the northern North Atlantic, Nordic and Arctic Seas from 1901 to 2011 (NODC Accession 0105532)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Historical temperature, salinity, oxygen and nutrients bottle and CTD data collected in the Arctic Ocean, Barents Sea, Greenland Sea, Kara Sea, North Atlantic Ocean,...

  12. Electroosmotic dewatering of chalk sludge, iron hydroxide sludge, wet fly ash and biomass

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, H.K.; Kristensen, I.V.; Ottosen, L.M.; Villumsen, A. [Dept. of Geology and Geotechnical Engineering, The Technical Univ. of Denmark, Lyngby (Denmark)

    2001-07-01

    Electroosmotic dewatering has been tested in laboratory cells for 4 different porous materials: chalk sludge, iron hydroxide sludge, wet fly ash and biomass sludge from enzyme production. In all cases it was possible to remove water when passing electric DC current through the material. Casagrande's coefficients for the three materials where determined at different water contents. In the electroosmotic experiments shown in this work chalk can be dewatered from 40% to 79% DM (dry matter), fly ash from 75 to 82% DM, iron hydroxide sludge from 2.7 to 19% DM and biomass from 3 to 33% DM. The process was not optimised indicating that higher dry matter contents could be achieved. (orig.)

  13. Groundwater conversion areas in chalk in the southern Frankish Alps

    International Nuclear Information System (INIS)

    Pfaff, T.

    1987-01-01

    In order to collect hydro-geological data, chalk water marking was done and/or interpreted, water balances were produced, the contents tritium, oxygen 18, calcium, magnesium and the groundwater temperatures and electrolytic conductivity of the groundwater were examined and the dry weather drainage of individual sources was analysed. (orig./PW) [de

  14. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the Barents Sea, North Greenland Sea and Norwegian Sea from 1999-10-03 to 1999-10-11 (NODC Accession 0113888)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113888 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the Barents Sea, North Greenland Sea and Norwegian...

  15. Holocene North Atlantic Overturning in an atmosphere-ocean-sea-ice model compared to proxy-based reconstructions

    NARCIS (Netherlands)

    Blaschek, M.; Renssen, H.; Kissel, C.; Thornalley, D.

    2015-01-01

    Climate and ocean circulation in the North Atlantic region changed over the course of the Holocene, partly because of disintegrating ice sheets and partly because of an orbital-induced insolation trend. In the Nordic Seas, this impact was accompanied by a rather small, but significant, amount of

  16. Cost and time models for the evaluation of intermodal chains by using short sea shipping in the North Sea Region: the Rosyth-Zeebrugge route

    DEFF Research Database (Denmark)

    Lopez, Alba Martínez; Kronbak, Jacob; Jiang, Liping

    2015-01-01

    This paper is framed in the context of the EU Interreg IVB North Sea Region project Food Port. In line with this project, this paper aims to define mathematically cost and time models able to provide realistic information about the performances of road haulage and of intermodal chains using short...

  17. A 3D gravity and magnetic model for the Entenschnabel area (German North Sea)

    Science.gov (United States)

    Dressel, Ingo; Barckhausen, Udo; Heyde, Ingo

    2018-01-01

    In this study, we focus on structural configuration of the Entenschnabel area, a part of the German exclusive economic zone within the North Sea, by means of gravity and magnetic modelling. The starting point of the 3D modelling approach is published information on subseafloor structures for shallow depths, acquired by wells and seismic surveys. Subsequent gravity and magnetic modelling of the structures of the deeper subsurface builds on this geophysical and geological information and on gravity and magnetic data acquired during a research cruise to the Entenschnabel area. On the one hand, our 3D model shows the density and susceptibility distribution of the sediments and the crust. In addition, the potential field modelling provides evidence for a differentiation between lower and upper crust. The thickness distribution of the crust is also discussed with respect to the tectonic framework. Furthermore, gravity as well as magnetic modelling points to an intrusive complex beneath the Central Graben within the Entenschnabel area. On the other hand, this work provides a geological-geophysical consistent 3D gravity and magnetic model that can be used as a starting point for further investigation of this part of the German North Sea.

  18. The potential for storing carbon dioxide in the rocks beneath the UK Southern North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Michelle Brook; Karen Shaw; Ceri Vincent; Sam Holloway [British Geological Survey, Keyworth (United Kingdom). Kingsley Dunham Centre

    2003-07-01

    The CO{sub 2} storage potential of the UK sector of the Southern North Sea has been intensively studied in the EU Energie Programme project: 'European Potential for Geological Storage of Carbon Dioxide from Fossil Fuel Combustion' (acronym GESTCO). This project is determining the cost and practicality of extending carbon dioxide storage technology similar to that being demonstrated at the Sleipner West gas field to the major industrial plant of western Europe. The characteristics of the two extensive, well sealed reservoir rocks - the Rotliegend Sandstone and the Bunter Sandstone are discussed and their capacity to store injected CO{sub 2} is estimated. The Sherwood Sandstone, the part of the Bunter Sandstone onshore in eastern England, is used for water supply which could be an issue of conflict of use. A cost estimate of CO{sub 2} sequestration into the Bunter Sandstone, made in 1966 is given. A table gives CO{sub 2} storage capacity of the Rotliegend and Triassic Gas fields of the Southern North Sea. 11 refs., 3 figs., 2 tabs.

  19. Identification of seafloor provinces - specific applications at the deep-sea Hà ¥kon Mosby Mud Volcano and the North Sea

    OpenAIRE

    Jerosch, Kerstin

    2006-01-01

    The identification of distinct provinces is currently an emphasis of marine research geosciences. Typological approaches for the Hà ¥kon Mosby Mud Volcano and the North Sea combining geological, biological and chemical properties are accomplished by geostatistical, multivariate statistical, and GIS techniques. Besides scientific needs seafloor provinces support management decisions related to upcoming economic use of the seafloor and bear up to model spatio-temporal connections and changes o...

  20. Reconstructing Quaternary Rhine-Meuse dynamics in the southern North Sea: Architecture, seismo-lithofacies associations and malacological biozonation

    NARCIS (Netherlands)

    Rijsdijk, K.F.; Kroon, I.C.; Meijer, T.; Passchier, S.; Dijk, T.A.G.P. van; Bunnik, F.P.M.; Janse, A.C.

    2013-01-01

    Mapping the Middle to Upper Pleistocene Rhine-Meuse sequence in the southern North Sea based on new core and seismic data has allowed a detailed palaeoenvironmental re-assessment. An integrated seismo-lithostratigraphic and malacological biostratigraphic framework is correlated with the optically