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Wyszukujesz frazę "Christiansen, C." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Environmental changes in the central Baltic Sea during the past 1000 years: inferences from sedimentary records, hydrography and climate
Autorzy:
Leipe, T.
Dippner, J.W.
Hille, S.
Voss, M.
Christiansen, C.
Bartholdy, J.
Powiązania:
https://bibliotekanauki.pl/articles/47746.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
bottom water anoxia
sediment
hydrography
environment condition
little ice age
Baltic Sea
modern warm period
saline water
environment change
climate
Gotland Basin
Opis:
Short sediment cores from the eastern Gotland Basin were investigated using a multi-proxy approach in order to reconstruct the environmental conditions of the area during the past 1000 years. Sediment data and facies were discussed in relation to hydrographic features (salinity, oxygen) and climate change. During the medieval warm period (MWP), from about 900 to 1250 AD, the hydrographic and environmental conditions were similar to those of the present time (modern warm period, since about 1850): a temporally stable halocline, caused by regular saline water inflows from the North Sea, prevents vertical mixing and leads to bottom water anoxia and the deposition of laminated, organic-rich sapropels. During the period from about 1250 to 1850, referred to as the cold phase (including the Little Ice Age), the environmental conditions of the central Baltic Sea were distinctly different: the lower salinity, resulting from reduced North Sea water inflows, allowed vertical convection of the water column and long-term stable ventilation of the sea bed (oxic stage). Both the productivity of the planktonic ecosystem as well as the preservation of organic matter in the sediments improved during the warm periods. The anthropogenic impact can be identified within the recent laminated sequence by a temporal reconstruction of pollutant deposition. Our findings imply a climate-change driven shift in the environmental conditions and the ecosystem of the Baltic from the north to the south and back to the north.
Źródło:
Oceanologia; 2008, 50, 1; 23-41
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deposition of organic matter and particulate nitrogen and phosphorus at the North Sea - Baltic Sea transition - a GIS study
Autorzy:
Jansen, D.L.
Lundqvist, D.P.
Christiansen, C.
Lund-Hansen, L.C.
Balstrom, T.
Leipe, T.
Powiązania:
https://bibliotekanauki.pl/articles/48457.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
organic matter
nutrient
deposition
nitrogen
Baltic Sea
sediment
phosphorus
North Sea
Geographic Information System
Opis:
A GIS (Geographical Information System) based study on deposition in the North Sea – Baltic Sea transition area has been carried out. The study is based on (i) a digital bathymetry model, (ii) 93 available 210Pb/137Cs sedimentation rate estimations, (iii) grain-size distributions, organic matter, C, N and P content of 64 top 1 cm sediment samples from the study area, and (iv) GIS-based modelling of resuspension potentials based on wind statistics. With the use of regression statistics on depth, resuspension potential and sediment characteristics, results are extrapolated area-wide from the 64 sampling positions. The area is divided into sediment types and classified as accumulation or erosion/transport bottoms. Model results show good agreement with existing maps of sediment distributions, indicating that the sediment distribution is governed to a large extent by windinduced waves. Correlations of sediment types, their deposition rates and their N and P contents were used to estimate spatial deposition rates. In all, the yearly deposition in the study area amounts to 2.8 million tons of organic matter, 0.14 million tons of total nitrogen, and 0.035 million tons of total phosphorus. Correlations of sediment types and dry bulk densities were used to infer spatial inventories of organic matter and total nitrogen and phosphorus in the top 1 cm of the sediments. A total of 100 million tons of organic matter, 4 million tons of total nitrogen, and 0.019 million tons of total phosphorus are contained in the top 1 cm of the sediments in the study area. In general, the deep parts of the study area with low resuspension potentials act as sinks for the fine-grained sediments and their associated particulate nutrients.
Źródło:
Oceanologia; 2003, 45, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and hydraulically-induced recycling of phosphorus in the North Sea-Baltic Sea transition zone
Autorzy:
Kepp, R.R.
Struve, A.
Christiansen, C.
Lund-Hansen, L.C.
Nielsen, M.H.
Vang, T.
Powiązania:
https://bibliotekanauki.pl/articles/47459.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Little Belt
transport
transition zone
Baltic Sea
recycling
phosphorus
water transport
hydraulic mixing
North Sea
water chemistry
water column
Opis:
Bottom-mounted acoustic Doppler current profiler measurements indicate that the net transport of water (844 m3 s−1) in the Little Belt makes up only 6% of the total transport between the Baltic Sea and the North Sea. This is a smaller percentage than the 9% commonly found in the literature. Owing 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 mixing in an area of hydraulic control in the narrow part of the Little Belt. Comparisons of phosphorus profiles in stratified waters and in the mixing area indicate a yearly entrainment of 15 tonnes P from the bottom water to the surface layer. This vertical transport of P forms part of an internal loop in the general transport between the Baltic Sea and the North Sea. Compared to the transport observed 15–16 years ago, the present net phosphorus transport of 163 tonnes yr−1 from the Baltic Sea through the Little Belt is substantially lower.
Źródło:
Oceanologia; 2006, 48, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sea wave energy converter - WAVE DRAGON MW for few megawatts power range
Przekształtnik energii fal morskich MW WAVE Dragon na poziomie mocy w zakresie kilku megawatów
Autorzy:
Kaźmierkowski, M.
Jasiński, M.
Malinowski, M.
Płatek, T.
Styński, S.
Antoniewicz, P.
Kołomyjski, W.
Świerczyński, D.
Soerensen, H. C.
Friis-Madsen, E.
Christiansen, L.
Knapp, W.
Zhou, Z.
Igic, P.
Powiązania:
https://bibliotekanauki.pl/articles/159473.pdf
Data publikacji:
2007
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Elektrotechniki
Tematy:
energia odnawialna
energia fal morskich
przekształtnik energoelektroniczny
generatory
renewable energy
energy from sea waves
power electronics converters
generators
Opis:
The paper has as an objective to combine and disseminate a brief knowledge on generators and power electronics for Wave Dragon MW (WDMW) Power Take Off system. Wave Dragon MW captures power from sea waves by means of low-head turbines and converts it into rotating mechanical power. In recent years because of energy saving problem on almost whole world power electronics and electric machines as well as renewable energy market has been intensively developed. Problems which can appear in conversion mechanical power to electrical power in WDMW can be expected to be similar as in wind turbine. Therefore, state of the art briefly can base on state of the art for wind turbines. However, subject of the mechanical energy conversion from sea waves to electrical energy is not well identified and further research should be curried out.
Artykuł ma na celu zebranie i przedstawienie podstawowych informacji na temat przekształtnika energii fal morskich Wave Dragon MW (WDMW). Ponadto również wstępne wyniki symulacyjne zespołu generator-przekształtnik energoelektroniczny - sieć.
Źródło:
Prace Instytutu Elektrotechniki; 2007, 231; 5-16
0032-6216
Pojawia się w:
Prace Instytutu Elektrotechniki
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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