Exposure of phytoplankton to ekofisk crude oil     

Kjetill Østgaard  Ingvar Eide  Arne Jensen 《Marine environmental research》1984,11(3):183-200

Solutions of Ekofisk crude oil in sea water were prepared by slow stirring for 21h in a closed system. Headspace and GC/MS techniques were applied to establish dose composition and levels. The standardized test medium produced in a closed system contained approximately 14 mg oil per litre and was dominated by low molecular weight aromatic hydrocarbons and phenols.The toxicity of the standarized oil-containing medium to three marine diatoms was studied in a cage culture turbidostat and by conventional batch culture technique. The three algal species differed in sensitivity to the oil compounds, but showed identical ranking in both test systems.Standardized test medium diluted to 50% with respect to oil content stopped the growth of the most sensitive alga, Skeletonema costatum. For comparison naphthalene was applied and gave 50 % growth reduction at a concentration of 400 μg litre^?1. The growth of Chaetoceros ceratosporum was only slighty affected by the full strength standard test medium, which had no influence on the growth of Phaeodactylum tricornutum, the least sensitive organism. The presence of an oil layer on the surface of the standard test medium during the growth test greatly increased its toxicity and blocked completely the photosynthesis even of P. tricornutum after 4 days.  相似文献   

Reactive Nitrogen Compounds at Spitsbergen in the Norwegian Arctic     

S. Solberg  T. Krognes  F. Stordal  OØ Hov  H. J. Beine  D. A. Jaffe  K. C. Clemitshaw  S. A. Penkett 《Journal of Atmospheric Chemistry》1997,28(1-3):209-225

Simultaneousindependent measurements of NO_y and NO_x(NO_x= NO + NO₂) by high-sensitivitychemiluminescence systems and of PAN (peroxyacetylnitrate) and PPN (peroxypropionyl nitrate) by GC-ECDwere made at Spitsbergen in the Norwegian Arcticduring the first half year of 1994. The average mixingratio of the sum of PAN and PPN (denoted PANs)increased from around 150 pptv in early winter to amaximum of around 500 pptv in late March, whereasepisodic peak values reached 800 pptv. This occurredsimultaneously with a maximum in ozone which increasedto 45–50 ppbv in March–April. The average NO_xmixing ratio was 27 pptv and did not show any cyclethrough the period. The NO_y mixing ratio showeda maximum in late March, while the difference betweenNO_y and PAN decreased during spring. This is anindication of the dominance of PAN in the NO_ybudget in the Arctic, but possible changes in theefficiency of the NO_y converter could alsocontribute to this. Although most PAN in theArctic is believed to be due to long range transport,the observations indicate local loss and formationrates of up to 1–2 pptv h^-1 in April–May.Measurements of carbonyl compounds suggest thatacetaldehyde was the dominant, local precursor ofPAN.Now at 1.  相似文献   

Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway     

Torgeir O. Rthe  Jostein Bakke  Eivind Wilhelm Nagel Stren 《Boreas: An International Journal of Quaternary Research》2019,48(3):616-634

A sudden release of large volumes of water during a glacier outburst flood (GLOF) is a major hazard worldwide. Here, we identify the sedimentary signature of glacial and non‐glacial processes, including GLOFs, based on lacustrine sediments from the distal glacier‐fed Lake Buarvatnet in western Norway. Historically documented GLOFs in 2002 CE and during the 1980s CE are identified in the ²¹⁰Pb‐ and ¹⁴C‐dated sediments. These events have the same sedimentary signature as 12 earlier events throughout the Holocene interpreted to represent previous GLOFs in the catchment. The GLOFs are interpreted to have occurred during periods when the glacier extent was similar to the modern positions, and the events are thus used to pinpoint past positions of the glacier terminus and, hence, the equilibrium line altitudes (ELAs). The results indicate that the glacier Svartenutbreen, located at the eastern part of Folgefonna, had a similar size in 2002 CE as c. 8200–8300 cal. a BP, corresponding to the 8.2 ka event in the North Atlantic region. The regrowth of Sørfonna after the Holocene Thermal Optimum occurred at c. 6900 cal. a BP and Svartenutbreen was at modern size and extent in the periods c. 6400, c. 5450, c. 4850, c. 3850, c. 3550 and c. 1650 cal. a BP. Since 1650 cal. a BP, we infer that the glacier was larger than the 2002 CE glacier extent until 1910 CE when a GLOF occurred. Svartenutbreen has been retreating since 1910 CE, which led to the ice damming of the two historical GLOFs in the 1980s and 2002 CE separated by a glacier advance in the 1990s CE. The findings are discussed and compared to other regional glacier reconstructions in Norway, and emphasize the value of identifying and utilizing GLOFs as an indicator of past ELA variability.  相似文献   

Linking past flood frequencies in Norway to regional atmospheric circulation anomalies     

Eivind N. Støren  Erik W. Kolstad  Øyvind Paasche 《第四纪科学杂志》2012,27(1):71-80

Analysis of two continuous, high‐resolution palaeo‐flood records from southern Norway reveals that the frequency of extreme flood events has changed significantly during the Holocene. During the early and middle Holocene, flood frequency was low; by contrast, it was high over the last 2300 years when the mean flood frequency was about 2.5–3.0 per century. The present regional discharge regime is dominated by spring/summer snowmelt, and our results indicate that the changing flood frequency cannot be explained by local conditions associated with the respective catchments of the two lakes, but rather long‐term variations of solid winter precipitation and related snowmelt. Applying available instrumental winter precipitation data and associated sea‐level pressure re‐analysis data as a modern analogue, we document that atmospheric circulation anomalies, significantly different from the North Atlantic Oscillation (NAO), have some potential in explaining the variability of the two different palaeo‐flood records. Centennial‐scale patterns in shifting flood frequency might be indicative of shifts in atmospheric circulation and shed light on palaeo‐pressure variations in the North Atlantic region, in areas not influenced by the NAO. Major shifts are found at about 2300, 1200 and 200 years ago (cal. a BP). Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway     

VALENTIN BURKI  LOUISE HANSEN  OLA FREDIN  THORBJØRN A. ANDERSEN  ACHIM A. BEYLICH  MICHEL JABOYEDOFF  EILIV LARSEN  JAN‐FREDERIK TØNNESEN 《Boreas: An International Journal of Quaternary Research》2010,39(3):551-566

Burki, V., Hansen, L., Fredin, O., Andersen, T. A., Beylich, A. A., Jaboyedoff, M., Larsen, E. & Tønnesen, J.‐ F. 2009: Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway. Boreas, Vol. 39, pp. 551–566. 10.1111/j.1502‐3885.2009.00133.x. ISSN 0300‐9483 Bødalsbreen is an outlet glacier of the Jostedalsbreen Ice Field in western Norway. Nine moraine ridges formed during and after the maximum extent of the Little Ice Age (LIA). The stratigraphy of proglacial sediments in the Bødalen basin inside the LIA moraines is examined, and corresponding sediment volumes are calculated based on georadar surveys and seismic profiling. The total erosion rates (e_tot) by the glacier are determined for the periods AD 1650–1930 and AD 1930–2005 as 0.8 ± 0.4 mm/yr and 0.7 ± 0.3 mm/yr, respectively. These rates are based on the total amount of sediment delivered to the glacier margin. The values are almost one order of magnitude higher than total erosion rates previously calculated for Norwegian glaciers. This is explained by the large amount of pre‐existing sediment that was recycled by Bødalsbreen. Thus, the total erosion rate must be considered as a composite of eroded bedrock and of removed pre‐existing sediments. The total erosion rate is likely to vary with time owing to a decreasing volume of easily erodible, unconsolidated sediment and till under the glacier. A slight increase in the subglacial bedrock erosion is expected owing to the gradually increasing bedrock surface area exposed to subglacial erosion.  相似文献   

The Alta case: Learning from the errors made in a human ecological conflict in Norway     

Øystein Dalland 《Geoforum》1983,14(2):193-203

This paper explores the historical, geographical and human ecology aspects of an extreme conflict between development and conservation in northern Scandinavia. Development of hydro-power projects not only affects the physical environment but also conflicts with the culture of a distinct ethnic community, the Sami Lapps. Over one hundred power and mining projects have now been constructed in Sami territory, the cumulative effects of which have focused opposition to the Alta—Kautokeino Waterway. The long- and short-term origins of the conflict are analysed in the light of Sami ecology and Norwegian administrative principles. How the Sami ecology has affected the national frontiers and recent resource management issues are described. Finally, the importance of environmental protests and public hearings in the resolution of fundamental resource/land use conflicts is discussed. The author concludes that the basic aspects of land use conflict may be analysed by using a symbiotic ecology model and applying this to technical human activities.  相似文献   

Variability in fluxes of nutrients (N,P, Si) into the North Sea from the Atlantic Ocean and skagerrak caused by variability in water flow     

Remi W. P. M. Laane  Einar Svendsen  Günther Radach  Gerard Groeneveld  Peter Damm  Johannes PÄtsch  D. S. Danielssen  Lars FØyn  Martin Skogen  Marek Ostrowski  Kees J. M. Kramer 《Ocean Dynamics》1996,48(3-4):401-419

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Atmospheric concentrations of nonmethane hydrocarbons at a North European coastal site     

Øystein Hov  Norbert Schmidbauer 《Journal of Atmospheric Chemistry》1992,14(1-4):515-526

Two years of individual nonmethane hydrocarbon (NMHC) measurements at a rural site close to the south coast of Norway show that there was a distinct annual cycle with a late winter maximum and late summer minimum in the slowly reacting NMHCs acetylene, ethane, propane and i- and n-butane. The average January—March concentrations were a factor 2–4 higher than the July-September concentrations. Also ethene, propene and the pentanes show a similar annual cycle, but the individual scatter in the measurements in particular of propene, is large. The highest concentrations of NMHC were found in winter for easterly transport on a regional scale (out to 1500 km from the site), and for southeasterly transport in the summer.  相似文献   

Two types of extremely short lasting decimetric bursts and their possible relation to processes in solar magnetic traps     

Øystein Elgarøy  Ole P. Sveen 《Solar physics》1973,32(1):231-240

High resolution spectral observations between 500 MHz and 550 MHz on 1972 October 25, revealed an emission event of special interest. The main feature was bursts with a single frequency duration of about 0.09 s and with a bandwidth of the same order of magnitude as the band covered by the spectrograph. The bursts occurred in showers' which lasted for one or two minutes and which were separated by quiet intervals of roughly the same length. Frequently the activity assumed a periodic nature. Periods between 0.1 s and 0.3 s were found. The most remarkable feature of the records was a very large number of bursts with the same duration as the wide band bursts, but showing a bandwidth of a mere 1–2 MHz.The wide band bursts may be plasma waves excited by proton streams trapped in coronal magnetic fields and the narrow band bursts may possibly be explained as perpendicular electrostatic electron cyclotron waves.  相似文献   

Development and verification of deep-water blowout models   总被引：2，自引：0，他引：2  

Johansen Ø 《Marine pollution bulletin》2003,47(9-12):360-368

Modeling of deep-water releases of gas and oil involves conventional plume theory in combination with thermodynamics and mass transfer calculations. The discharges can be understood in terms of multiphase plumes, where gas bubbles and oil droplets may separate from the water phase of the plume and rise to the surface independently. The gas may dissolve in the ambient water and/or form gas hydrates––a solid state of water resembling ice. All these processes will tend to deprive the plume as such of buoyancy, and in stratified water the plume rise will soon terminate. Slick formation will be governed by the surfacing of individual oil droplets in a depth and time variable current. This situation differs from the conditions observed during oil-and-gas blowouts in shallow and moderate water depths. In such cases, the bubble plume has been observed to rise to the surface and form a strong radial flow that contributes to a rapid spreading of the surfacing oil. The theories and behaviors involved in deepwater blowout cases are reviewed and compared to those for the shallow water blowout cases.  相似文献