Bundesamt fur Seeschifffahrt und Hydrographie BSH

Hamburg, Germany

Bundesamt fur Seeschifffahrt und Hydrographie BSH

Hamburg, Germany
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Hufnagl M.,University of Hamburg | Payne M.,Technical University of Denmark | Lacroix G.,Royal Belgian Institute Of Natural Sciences | Bolle L.J.,Institute for Marine Resources and Ecosystem Studies | And 19 more authors.
Journal of Sea Research | Year: 2016

Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole and plaice we determined which fraction of particles released in the respective spawning areas would reach a coastal marine protected area. For herring we determined the fraction located in a wind park after a predefined time span. As temperature is more and more a focus especially in biological and global change studies, furthermore inter-model variability in temperatures experienced by the virtual particles was determined. The main focus was on the transport variability originating from the physical models and thus biological behavior was not included. Depending on the scenario, median experienced temperatures differed by 3. °C between years. The range between the different models in one year was comparable to this temperature range observed between modelled years. Connectivity between flatfish spawning areas and the coastal protected area was highly dependent on the release location and spawning time. No particles released in the English Channel in the sole scenario reached the protected area while up to 20% of the particles released in the plaice scenario did. Interannual trends in transport directions and connectivity rates were comparable between models but absolute values displayed high variations. Most models showed systematic biases during all years in comparison to the ensemble median, indicating that in general interannual variation was represented but absolute values varied. In conclusion: variability between models is generally high and management decisions or scientific analysis using absolute values from only one single model might be biased and results or conclusions drawn from such studies need to be treated with caution. We further concluded that more true validation data for particle modelling are required. © 2017 Elsevier B.V.

Daraoui A.,Leibniz University of Hanover | Tosch L.,Leibniz University of Hanover | Gorny M.,Leibniz University of Hanover | Michel R.,Leibniz University of Hanover | And 6 more authors.
Journal of Environmental Radioactivity | Year: 2016

In this study, new data are presented for the iodine isotopes (127I, 129I and their isotopic ratios) and Cesium (137Cs) in water samples of the North Sea and the Baltic Sea in 2005 and 2009. This study supplements and extends the study of Michel et al. (2012). Iodine isotopes were separated from their matrix by using an anion exchange method and were determined by applying ICP-MS and AMS. 137Cs in seawater was determined after cesium ion exchange procedure enrichment by gamma-spectrometry. The concentrations of 127I in seawater of the North and Baltic Sea are fairly constant in each Sea with averages of (44 ± 2) and (21 ± 1) ng g-1, respectively, depending on the salinity. However, large variations of 129I concentrations in these areas were detected, which decreased along the French, Belgian, Dutch, German, and Danish shores. 129I/127I isotope ratios in the Baltic Sea are about 10 times lower than in the North Sea in 2009. The highest isotopic ratios (2.7 × 10-6) was detected in the English Channel east of the nuclear reprocessing plant at Cap de la Hague. The results confirm the result of our early study that the sources of 129I in the North Sea are primarily the nuclear reprocessing facilities at Sellafield (UK) and La Hague (F), and that in the Baltic Sea the inflow of water from North Sea through the Danish Straits dominates the occurrence of 129I. In 2009, the activity concentration of 137Cs was at least 6 times higher in the Baltic Sea (37 Bq m-3) than in the North Sea (5.9 Bq m-3), due to release of 137Cs from sediments in the Baltic Sea, which were contaminated by the Chernobyl accident and - to a minor degree - the atmospheric explosions of atomic bombs. The results are discussed by comparing the results of our previous work and the current study demonstrating the continuing disequilibrium of 129I/127I atomic ratio in the environmental compartments. © 2016 Elsevier Ltd.

PubMed | Bundesamt fur Seeschifffahrt und Hydrographie BSH, ETH Zurich and Leibniz University of Hanover
Type: | Journal: Journal of environmental radioactivity | Year: 2016

In this study, new data are presented for the iodine isotopes (

Michel R.,Leibniz University of Hanover | Daraoui A.,Leibniz University of Hanover | Gorny M.,Leibniz University of Hanover | Jakob D.,Leibniz University of Hanover | And 8 more authors.
Science of the Total Environment | Year: 2012

In order to obtain a comprehensive survey on the consequences of the marine 129I discharges from the European reprocessing plants La Hague and Sellafield, the distribution of 129I and 127I in surface waters of the North Sea, the English Channel, the Irish Sea, and the Northeast Atlantic was studied using accelerator mass spectrometry for 129I and ICP-MS for 127I. Samples of seawater were taken in the German Bight in May, September, and November 2005 and in the entire North Sea and the English Channel in August 2005. Further samples were obtained from the Irish Sea in June and August 2006 and from Arctic waters between Spitsbergen and Southern Norway in September 2005. 129I is a conservative tracer in seawater. The concentrations of 127I are relatively constant with exceptions of coastal areas with high biological activity and of areas influenced by influx from rivers and the Baltic Sea. The variability of the 129I/ 127I isotopic ratios is exclusively determined by admixture of 129I released from the reprocessing facilities Sellafield and La Hague to the seawater. The 129I/ 127I ratios were between 4×10 -9and 3×10 -6: at least 3 orders of magnitude higher than the natural equilibrium isotopic ratio 1.5×10 -12. 129I/ 127I ratios of a few times 10 -10 were only found in seawater from the Indian Ocean and from the Pacific at Hawaii. Comparison of the results obtained for seawater with those of a measurement of airborne iodine species and with iodine isotopes in precipitation in Northern Germany demonstrates the transfer of 129I and 127I from the sea into the atmosphere and the dominating role of the marine discharges for the atmospheric fallout of 129I in Western Europe. The results are discussed with the goal to estimate the relevance of the marine discharges for the contamination of the continental areas. © 2012 Elsevier B.V.

Dick S.,Bundesamt fur Seeschifffahrt und Hydrographie BSH | Kleine E.,Bundesamt fur Seeschifffahrt und Hydrographie BSH
2006 IEEE US/EU Baltic International Symposium, BALTIC 2006 | Year: 2016

At the Federal Maritime and Hydrographic Agency (BSH), a new model version of a circulation model is under development which will use not only an improved grid resolution but also a novel formulation of the vertical co-ordinate. The three-dimensional baroclinic circulation model (BSHcmod) is an important component of the operational model system, which has been running at the BSH for more than 20 years now. Important applications of the model system are the support of the BSH's water level prediction service, forecasting of oil drift paths and pollutant dispersion, as well as water quality studies. The circulation model simulates tidal, wind and density driven motion in the entire North Sea and Baltic Sea region. Two nested and interactively coupled grids are used for the German Bight and western Baltic Sea. The horizontal grid spacing of the new version is 900 m in the nested areas, and approx. 5 km in the other parts of the North Sea and Baltic. The vertical grid resolution has been improved as well. In addition, a new type of vertical co-ordinate representation has been implemented which allows layer thicknesses to be varied in time and space. With regard to the performance of general circulation models in a more general context, the new formulation provides a dynamic co-moving description of stratification and its maintenance. Internal dynamics are captured using weakly inclined flexible co-ordinate surfaces. The formulation is of the evolution type, and all common forms of vertical representation are recovered as special examples. © 2006 IEEE.

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