On the sulphur chemistry of a super-anoxic fjord, Framvaren, South Norway     

Leif G. Anderson  David Dyrssen  Per O.J. Hall 《Marine Chemistry》1988,23(3-4)

The concentrations of total carbonate (C_t), sulphate, sulphide, thiols and oxygen, the ratio between the stable sulphur isotopes ³⁴S and ³²S in sulphate and sulphide, and the density (used to calculate salinity) were determined on samples from the water column of Framvaren, a superanoxic fjord in southern Norway. From a depth of 18m (the oxic-anoxic boundary) the initial sulphate concentration, ([SO₄]_init), as calculated from salinity, is significantly higher than the sum of the measured sulphur species. This is attributed to a loss of sulphur from the water column. The amount of total carbonate produced, corrected for the initial concentration (C_t - 2.4 Sal/35) is found to be proportional to the amount of sulphate consumed, ([SO₄]_init - [SO₄]), according to the following relation C_t- 2.4 Sal/35 = 1.84 ([SO₄]_init - [SO₄]). Isotopic fractionation caused by bacterial sulphate reduction in the anoxic part of the water column produces sulphide with a δ³⁴S 40‰ lower than the δ³⁴S for sulphate at corresponding depths. The isotopic fractionation also results in δ³⁴S value for the remaining sulphate at depths below 80 m being considerably higher than the mean value for ocean water, which is close to + 20‰. The δ³⁴S values for sulphate at depths between 10 and 50 m were lower than + 20‰ which indicates oxidation of sulphide, which follows upon diffusion of sulphide from deeper parts of the water column and inflow of oxygenated seawater over the sill into the anoxic water of the fjord. A conclusive scenario of the Framvaren sulphur chemistry is presented.  相似文献   

The dynamics of the carbon cycle in the surface water of the Norwegian Sea     

Eva Falck  Leif G. Anderson   《Marine Chemistry》2005,94(1-4):43

Historical data of total dissolved inorganic carbon (C_T), together with nitrate and phosphate, have been used to model the evolution of these constituents over the year in the Atlantic water of the Norwegian Sea. Changes in nutrient concentration in the upper layer of the ocean are largely related to biological activity, but vertical mixing with the underlying water will also have an impact. A mixing factor is estimated and used to compute the entrainment of these constituents into the surface water from below. After taking the mixing contribution into account, the resulting nutrient concentration changes are attributed to biological production or decay. The results of the model show that the change in C_T by vertical mixing and by biological activity based on nutrient equivalents needs another sink to balance the carbon budget. It cannot be the atmosphere as the surface water is undersaturated with respect to carbon dioxide and is, thus, a source of C_T in this region. Inasmuch as the peak deficit of carbon is more than a month later than for the nutrients, the most plausible explanation is that other nitrogen and phosphate sources than the inorganic salts are used together with dissolved inorganic carbon during this period. As nitrate and phosphate show a similar trend, it is unlikely that the explanation is the use of ammonia or nitrogen fixation but rather dissolved organic nitrogen and phosphate, while dissolved organic carbon is accumulating in the water.  相似文献   

Formation of chemogenic calcite in super-anoxic seawater — Framvaren, southern Norway     

Leif G. Anderson  David Dyrssen  Jens Skei   《Marine Chemistry》1987,20(4)

Framvaren, a super-anoxic fjord in southern Norway, contains 7–8 mmoll⁻¹ of sulphide and a total carbonate concentration of 18.5 mmol kg⁻¹ in the bottom water. The chemistry of calcium has been studied, considering sources, biogenic and chemical processes and sedimentary sinks. Calcium associated with the bacteria biomass at the redox interface (18m depth) appears to be the primary source of dissolved calcium in the deep, anoxic water. Excess calcium and high total carbonate cause supersaturation of calcite, which is precipitated chemogenically. Calcite (and presumably some aragonite) is identified both in sediment trap material and the bottom sediments below the depth of supersaturation.  相似文献   

The behaviour of spawning herring in relation to a survey vessel     

Skaret  Georg; Axelsen  Bjorn Erik; Nottestad  Leif; Ferno  Anders; Johannessen  Arne 《ICES Journal of Marine Science》2005,62(6):1061-1064

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The strength of the Sun's polar fields   总被引：3，自引：0，他引：3  

Leif Svalgaard  Thomas L. Duvall Jr.  Philip H. Scherrer 《Solar physics》1978,58(2):225-239

The magnetic field strength within the polar caps of the Sun is an important parameter for both the solar activity cycle and for our understanding of the interplanetary magnetic field. Measurements of the line-of-sight component of the magnetic field generally yield 0.1 to 0.2 mT near times of sunspot minimum. In this paper we report measurements of the polar fields made at the Stanford Solar Observatory using the Fe i line 525.02 nm. We find that the average flux density poleward of 55° latitude is about 0.6 mT peaking to more than 1 mT at the pole and decreasing to 0.2 mT at the polar cap boundary. The total open flux through either polar cap thus becomes about 3 × 10¹⁴ Wb. We also show that observed magnetic field strengths vary as the line-of-sight component of nearly radial fields.  相似文献   

Glacial survival of blockfields on the Varanger Peninsula, northern Norway     

Jakob Fjellanger  Leif Srbel  Henriette Linge  Edward J. Brook  Grant M. Raisbeck  Franoise Yiou 《Geomorphology》2006,82(3-4):255-272

For more than hundred years it has been debated whether blockfields in mountain summit areas can be used to delimit the vertical extent of Pleistocene ice sheets. In this study the relationship between blockfields, developed in quartzites and sandstones on the Varanger Peninsula, northern Norway, and glacially derived features have been evaluated. Erratics and circular ablation moraines are superimposed on the blockfields and lateral meltwater channels are eroded into them. Glacial striations and other signs of glacial sculpturing are restricted to low-lying areas with channelled ice flow. Relative ages of the blockfields and the features in them are inferred, and the first measurements of in-situ produced cosmogenic nuclides from the Varanger Peninsula are reported. We conclude that the blockfields have survived underneath at least one thick, cold-based ice sheet. Thus, these blockfields cannot be used as indicators of ice-free conditions as previously suggested for southern Norway. Our results have implications for the potential for land surface preservation beneath ice sheets and for glacial reconstructions in northern Fennoscandia.  相似文献   

Late-Glacial and Early Holocene Environmental and Climatic Change at Lake Tambichozero, Southeastern Russian Karelia     

Barbara Wohlfarth  Ludmila Filimonova  Ole Bennike  Leif Bjrkman  Lars Brunnberg  Nadja Lavrova  Igor Demidov  Gran Possnert 《Quaternary Research》2002,58(3):261

High-resolution lithostratigraphy, mineral magnetic, carbon, pollen, and macrofossil analyses, and accelerator mass spectrometry ¹⁴C measurements were performed in the study of a sediment sequence from Lake Tambichozero, southeastern Russian Karelia, to reconstruct late-glacial and early Holocene aquatic and terrestrial environmental changes. The lake formed ca. 14,000 cal yr B.P. and the area around the lake was subsequently colonized by arctic plants, forming patches of pioneer communities surrounded by areas of exposed soil. A minor rise in lake productivity and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P. The rise in summer temperatures probably led to increased melting of remnant ice and enhanced erosion. The distinct increase in lake productivity and the development of open Betula-Populus forests, which are reconstructed based on plant macrofossil remains, indicate stable soils from 10,600 cal yr B.P. onward. Pinus and Picea probably became established ca. 9900 cal yr B.P.  相似文献   

Testing links between river patterns and in-channel characteristics using MRPP and ANOVA     

Leif M. Burge   《Geomorphology》2004,63(3-4):115-130

This study tests the assumption that the characteristics of channels within multiple channel rivers are different from those of single channel rivers. Some river restoration approaches propose radical transformation of river patterns, from multiple to single channels, based on the link between river patterns and their in-channel characteristics. Determining the links between river patterns and their in-channel characteristics is complicated by differences in geology, history, climate and discharge among rivers. Furthermore, multiple channel rivers are composed of a mosaic of channel types with a range of in-channel characteristics. This study minimizes these problems by analysing a single river containing neighbouring single and multiple channel patterns with little change in discharge downstream, and by analysing all channel types. The study addressed two objectives: to determine the hydraulic geometry, energy, and sediment mobility characteristics of neighbouring single and multiple channel river patterns, and to test for statistical differences in these characteristics between patterns. The Renous River shows a wandering pattern for 11.5 km, with multiple channels around semipermanent islands and abandoned channels in the flood plain. The river displays a single channel river pattern where channels are confined by their valley walls, upstream and downstream of wandering. The analysis was conducted at three scales. First, the confined single channel and wandering multiple channel patterns were compared (pattern scale). Second, the confined channel pattern was compared to single and multiple channel sections within the wandering pattern (section scale). Third, all channel types were compared (channel type scale). Multi response permutation procedure (MRPP) and analysis of variance (ANOVA) were used to analyze differences between channels. Difference tests found no simple discrimination between the single and multiple channel river patterns of the Renous River. Tests between the single confined and multiple wandering channel patterns found few differences in the in-channel variables. The tests did find differences between multiple channel sections within the wandering pattern and confined single channels; however, a greater number of differences were found between multiple channel and single channel sections within the wandering pattern, highlighting the variability within the wandering pattern. Two groups emerged when all channel types were tested for differences: perennial main-channels containing the thalweg, and ephemeral side-channels. Therefore, side-channels define the in-channel characteristics of wandering rivers because few differences were found among main-channels in either pattern. This analysis suggests that all channel types, not just main-channels, should be investigated to obtain a complete picture of a river pattern prior to any restoration efforts. Engineers must exercise caution when applying the link between river patterns and in-channel characteristics to river restoration efforts.  相似文献   

Attenuation models inferred from intraplate earthquake recordings     

Anders Dahle  Hilmar Bungum  Leif B. Kvamme 《地震工程与结构动力学》1990,19(8):1125-1141

Strong-motion recordings at 87 sites from 56 different intraplate earthquakes from North America, Europe, China and Australia have been used through a two-step regression analysis to develop new attenuation models for peak ground acceleration, and for pseudo-relative velocity for frequencies of 0.25, 0.5, 1.0, 2.0, 5.0 and 10.0 Hz, all for 5 per cent of critical damping. The estimates are obtained along with an analysis of residuals and scatter. A similar regression analysis has been performed also for Fourier spectra of acceleration, in which case the coefficient for the anelastic term has been interpreted in terms of a frequency dependent quality factor Q. The resulting Q-model shows a strong frequency sensitivity with values around 600–700 at 1 Hz, around 2000 at 10 Hz and around 5200 at 25 Hz. These PGA, PSV and Q results depend, however, on the underlying assumption for geometrical spreading, in particular for low frequencies.  相似文献   

Impaired osmoregulation in the shrimp Palaemon adspersus exposed to crude oil extract     

Susanne Pihl Baden 《Marine pollution bulletin》1982,13(6):208-210

Palaemon adspersus is a hyper- and hypo-osmoregulating shallow-water shrimp. For a maximum period of 34 days P. adspersus were exposed to 20, 70, 100 and 200 ppb WSF of North Sea crude oil. The osmotic concentration of the haemolymph was measured by freezing point depression once a week. The ability to maintain hyper-osmolality was significantly decreased (p<0.05) after one, two and three weeks exposure to 200, 70 and 100 ppb, respectively. No effect was observed in 20 ppb. After an accidental exposure of shrimps to 24 h acute oil pollution, they were placed in pure sea water. The ability to maintain hyper-osmolality was reduced one week after the accidental oil exposure, but was regained within three weeks.  相似文献