Cycling of trace metals (Mn, Fe, Mo, U, V, Cr) in deep pore waters of intertidal flat sediments     

Melanie Beck  Olaf Dellwig  Hans-Jürgen Brumsack 《Geochimica et cosmochimica acta》2008,72(12):2822-2840

Trace metals (Mn, Fe, Mo, U, Cr, V) were studied in pore waters of an intertidal flat located in the German Wadden Sea. The study system is an example of a permeable tidal flat system where pore water exchange is affected by tidal driven pressure gradients besides diffusion. Permanently installed in situ samplers were used to extract pore waters down to 5 m depth throughout one year. The samplers were either located close to the tidal flat margin or in central parts of the tidal flat. Despite dynamic sedimentological and hydrological conditions, the general trends with depth in deep tidal flat pore waters are remarkably similar to those observed in deep sea environments. Rates of trace metal cycling must be comparably large in order to maintain the observed pore water profiles. Trace metals further show similar general trends with depth close to the margin and in central parts of the tidal flat. Seasonal sampling revealed that V and Cr vary concurrent with seasonal changes in dissolved organic carbon (DOC) concentration. This effect is most notable close to the tidal flat margin where sulphate, DOC, and nutrients vary with season down to some metres depth. Seasonal variations of Mn, Fe, Mo, and U are by contrast limited to the upper decimetres of the sediment. Their seasonal patterns depend on organic matter supply, redox stratification, and particulate matter deposited on sediment surfaces. Pore water sampling within one tidal cycle provides evidence for pore water advection in margin sediments. During low tide pore water flow towards the creekbank is generated by a hydraulic gradient suggesting that deep pore waters may be seeping out of creekbank sediments. Owing to the enrichment of specific elements like Mn in pore water compared to sea water, seeping pore waters may have an impact on the chemistry of the open water column. Mass balance calculations reveal that the impact of deep pore waters on the Mn budget in the open water column is below 4%. Mn deep pore water discharge of the whole Wadden Sea is estimated to be about 9% of the total dissolved riverine Mn input into the Southern North Sea.  相似文献   

Oligocene sequence stratigraphy and basin development in the Danish North Sea sector based on log interpretations     

Mette Danielsen  Olaf Michelsen  Ole Rn Clausen 《Marine and Petroleum Geology》1997,14(7-8)

Five sequences are defined in the Oligocene succession of the Danish North Sea sector. Two of the sequences, 4.1a and 4.3, have been identified onshore Denmark.Two types of prograding lowstand deposits are recognized. Sand-dominated deposits occur proximally, comprising sharp-based forced regressive deposits covered with prograding low-stand deposits. Clay-dominated prograding lowstand deposits occur distally in the sequences. The highstand deposits are proximally represented by thick prograding sandy deposits and distally by thin and condensed intervals.The main sediment input direction was from the north and the northeast. A succession oif lithofacies, from shallow marine facies dominated by sand to outer shelf facies dominated by clay, is mapped in each of the sequences. An overall southward progradation of the shoreline took place during the Oligocene, interrupted only by minor shoreline retreats.  相似文献   

Benthic Standing Stock and Metabolic Activity in the Bathyal Red Sea from 17°N to 27°N     

Olaf  Pfannkuche 《Marine Ecology》1993,14(1):67-79

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Influence of seismic shooting on the lesser sandeel (Ammodytes marinus)     

Hassel  Arne; Knutsen  Tor; Dalen  John; Skaar  Kristian; Lokkeborg  Svein; Misund  Ole Arve; Ostensen  Oivind; Fonn  Merete; Haugland  Eli Kyrkjebo 《ICES Journal of Marine Science》2004,61(7):1165-1173

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A novel time-series station in the Wadden Sea (NW Germany): First results on continuous nutrient and methane measurements     

Maik Grunwald  Olaf Dellwig  Gerd Liebezeit  Bernhard Schnetger  Rainer Reuter  Hans-Jürgen Brumsack 《Marine Chemistry》2007

In autumn 2002 a time-series station was installed in the tidal inlet between the Islands of Langeoog and Spiekeroog (Southern North Sea, NW Germany) to continuously measure physical, chemical, and meteorological parameters, even during extreme weather conditions (gale-force storms, drifting ice). Inside the pole of the station sensor tubes are installed in direction of the prevailing tidal currents. The tubes are equipped with hydrographic sensors (pressure, temperature, conductivity) and allow retrieval of water for nutrient analysis by automated instruments located inside the pole. Dissolved methane and the nutrients ammonia, nitrite, nitrate, phosphate, and silicate are measured at the station.  相似文献   

Nocdap results: On the relationship of extreme waves and currents for design of offshore structures     

R. Lee Gordon  Finn-Erik Dahl  David J.H. Peters 《Ocean Engineering》1985,12(4):293-308

Simultaneous wind, wave, and current data during 21 storms spanning four winters at Tromsøflaket (230 m depth) were analysed to determine joint probabilities of occurrence. Waves were measured with a Waverider Buoy, winds with a recording anemometer onboard a vessel and currents at up to five depths with Aandera RCM-4 current meters. Measured currents were filtered to separate tidal currents from residual currents. In most of the statistical analyses, the actual current profiles were replaced with a simplified “equivalent” profile (constant above 50 m depth) whose magnitude was chosen to give the same drag load on a single pile as the actual profile when both profiles were combined with wave orbital velocities. The data suggest that the equivalent current is weakly correlated with the wave height. Within the range of the data analysed, an in-line equivalent residual current of 30 cm sec⁻¹ is adequate for design drag force calculations.The data presented here are used to illustrate a procedure for data analysis and are not suitable for use as design criteria.  相似文献   

The combined effect of transport and temperature on distribution and growth of larvae and pelagic juveniles of Arcto-Norwegian cod   总被引：5，自引：0，他引：5  

Vikebo  Frode; Sundby  Svein; Adlandsvik  Bjorn; Fiksen  Oyvind 《ICES Journal of Marine Science》2005,62(7):1375-1386

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Understanding El Niño — The importance of Grey Literature in Coastal Ecosystem Research and Management     

Sven Thatje  Jürgen Laudien  Olaf Heilmayer  Cornelia E. Nauen 《Marine Policy》2007

Access to information about past states of the environment and social systems is fundamental to understand, and cope with, the challenges of climate change and over-exploitation of natural resources at the onset of the 21st century. The loss of (old) data is a major threat to understanding better and mitigating long-term effects of human activities and anthropogenic changes to the environment. Although this is intuitively evident for old and local literature of any kind, even present-day international publishing of papers without the underlying raw data makes access to basic information a crucial issue. Here, we summarise experience resulting from a EU-funded International Science & Technology Cooperation (INCO) project (CENSOR) addressing Coastal Ecosystem Research and Management in the El Niño Southern Oscillation (ENSO) context. We show that indeed “Grey Literature” is still one of the most important sources of knowledge about natural science research and management of natural resource systems in Latin American countries. We argue that public archiving of original data of present-day research and old (Grey) Literature and easy public access are important for appreciating today's global environmental challenges caused by human activities, both past and present.  相似文献   

Origin of Pleistocene-Holocene ashes of the Russian northeast based on trace and rare earth element data     

V. G. Sakhno  L. I. Bazanova  O. Yu. Glushkova  I. V. Melekestsev  V. V. Ponomareva  A. A. Surnin  J. Olaf 《Doklady Earth Sciences》2006,411(9):1351-1356

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Weathering characteristics of arctic islands in northern Norway     

yvind Paasche  Jrund Raukleiv Strmse  Svein Olaf Dahl  Henriette Linge 《Geomorphology》2006,82(3-4):430-452

The arctic islands of the Lofoten-Vesterålen archipelago in northern Norway have a wide distribution of weathered land surfaces commonly located above 250 m with several apparent similarities. In order to investigate the characteristics of (deep) weathering in this region, northern Langøya and Hadseløya were chosen for in-depth analyses. Eight weathering profiles were excavated from various surfaces, and the stratigraphies were logged in detail. Material was collected throughout the weathering horizons, and all samples were subsequently analysed for clay mineralogy (< 63 μm fraction) and grain size distribution. The sampling strategy was complemented by samples from additional saprolites and other landforms such as moraines and rock glaciers. The XRD results indicate that the presence of secondary minerals, such as gibbsite (Al(OH)₃) and kaolinite (Al₂Si₂O₅(OH)₄), are very common throughout the profiles. Gibbsite is an extreme end product of silicate weathering and usually associated with a warmer and more humid climate, as found in Scandinavia during the Tertiary. The grain size analyses (< 63 μm) show that the finer silt fractions (< 8 μm) tend to be high in the profiles (20–40%), with significant amounts of clay (5–15%) demonstrating that the regolith itself is susceptible to frost sorting mechanisms.¹⁰Be exposure dates from in situ quartz knobs on tors and boulders of local origin suggest > 40,000 years of subaerial conditions. Considering the steady surface erosion, this figure should be viewed as an absolute minimum age estimate. Mapping of the superficial sediments and geomorphological features of the study areas has revealed several common morphological features, which indicate dominance of glacial and periglacial processes in the areas lying below the lower boundary of blockfields (c. 250 m). The weathering mantles are not a periglacial end product, but rather a relict tertiary landform that were modulated by permafrost processes as well as biological processes at later stages. The regolith cover constrain the vertical extension of warm-based Quaternary ice sheets challenging the notion of a parabolic ice mass consuming every mountain top of Lofoten and Vesterålen.  相似文献