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Number of results: 7
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Abstract

The buoyant hypopycnal flow of brackish water and suspended sediment transport and settling were studied in two sub-polar fjords: the glacial Kongsfjörden and the outwash (non-glacial contact) Adventfjörden, Svalbard . The data presented indicates faster water mixing on the tidal flat in comparison to the englacial runoff, which leads to faster horizontal density gradients decreases in the non-glaciated fjord. The fast settling of particles in the narrow zone of the steep slope at the edge of the tidal flat leads to the removal of 25% of the surface suspended sediment. The rapid settling is due to increasing salinity, decreasing velocity, and flocculation of fine particles. The fast settling of suspended particulate matter (SPM) in the tidal flat area causes sediment redeposition and resuspension followed by sediment transport along the bottom with hyperpycnal flows. This leads to grain sorting in the fjord head. In contrast, at the glacier front, SPM is transported farther into the fjord, where tidal pumping and water mixing lead to the removal of 71% of total SPM. The fjords investigated represent two different sedimentological regimes. In the glaciated Kongsfjörden, the buoyant hypopycnal flow of brackish water is the main sediment transporting factor. In the non-glacial Adventfjörden, hyperpycnal flows transport sediment along the bottom.
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Abstract

Modern hydrology of a typical Arctic fjord (Hornsund, SW Spitsbergen, Sval− bard) was investigated and compared with commonly used in paleoceanography proxies: benthic foraminiferal assemblages and their stable isotope (#2;18O and #2;13C) composition. The benthic foraminifera from Hornsund comprised 45 species and 28 genera. Their spatial variations follow the zonation pattern, resulting from the influence of Atlantic water at the fjord mouth and glacial meltwaters at the fjord head. At the mouth of the fjord, the total number of species and the contribution of agglutinating species were the highest. In the in− ner part of fjord, the foraminiferal faunas were poor in species and individuals, and aggluti− nating species were absent. “Living” (stained) foraminifera were found to be common throughout the short sediment cores (~10 cm long) studied. The stable isotope values of #2;18O and #2;13C were measured on tests of four species: Elphidium excavatum forma clavata, Cassidulina reniforme, Nonionellina labradorica and Cibicides lobatulus. The results con− firmed the importance of species−specific vital effects, particularly in the case of C. loba− tulus. The variability in the isotopic composition measured on different individuals within a single sample are comparable to isotopic composition of the same species test between sam− pling stations. The temperatures and bottom water salinities calculated from #2;18O values in different foraminifera tests mirrored those recorded for bottom waters in the central and outer fjords relatively well. However, in the case of the inner fjord, where winter−cooled bottom waters were present, the calculated values from #2;18O were systematically higher by about 2#3;C. The obtained results imply that particular caution must be taken in interpretation of fjord benthic foraminifera assemblages in high resolution studies and in selection of ma− terial for isotope analyses and their interpretation in cores from inner fjords or silled fjords, where winter−cooled waters may be present.
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Abstract

The sedimentary environment, sediment characteristics and age−depth models of sediment sequences from Arctic lakes Revvatnet and Svartvatnet, located near the Polish Polar Station in Hornsund, southern Svalbard (77 ° N), were studied with a view to establishing a basis for paleolimnological climate and environmental reconstructions. The results indicate that catchment−to−lake hydroclimatic processes probably affect the transportation, distribution and accumulation of sediments in different parts of lakes Revvatnet and Svartvatnet. Locations with continuous and essentially stable sedimentary environments were found in both lakes between water depths of 9 and 26 m. We used several different dating techniques, including 137 Cs, 210 Pb, AMS 14 C, and paleomagnetic dating, to provide accurate and secured sediment chronologies. A recovered sequence from the northern basin of Revvatnet spans more than one thousand years long with laminated stratigraphy in the upper part of the sediment. Based on AMS 14 C dates, it is possible to suppose that Revvatnet basin was not occupied by a valley glacier during the Little Ice Age. The dates were supported by 137 Cs chronologies, but not confirmed with other independent dating methods that extent beyond the last 50 years. A sedimentary sequence from the northern basin of Svartvatnet provides a potential archive for the study of climate and environmental change for the last ca. 5000 years. Based on the stratigraphy and a Bayesian age−depth model of AMS 14 C and paleosecular variation (PSV) dates, the recovered sediment sections represent a continuous and stable sedimentation for the latter half of the Holocene.
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Abstract

Chlorophyll α, phytoplankton, suspensions and zooplankton beneath the fast ice have been studied in Spitsbergen fjords (Hornsund, Bellsund, Sassenfjord, Gronfjord and Kongsfjord) in 1982, 1984/85,1987 and 1988. Observations on ice associated Polar cod and wildlife have been collected simultaneously. There were no typical sympagic communities observed at the West Spitsbergen fast ice. Exception was spring 1982 and 1988 when drifting ice from Barents Sea contributed to the fjords fauna. Fast ice on the investigated fjords was poor in adjacent zooplankton (biomass below 0.06 g/m3). Ice phytoplankton reflects the autumn situation and no specific communities of algae have been found. Chlorophyll α amount and organic sedimentation from ice and from the adjacent water were very similar (0.4 to 1.7 mg/m3 chlorophyll and 8 to 10 g d.w./m2/day sedimenling matter). The diet of Polar cod reflected the food items occurrence, Calanus has been the most common food. N o specific concentration of seabirds have been observed at fjords ice.
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Abstract

Suspended matter, phytoplankton and light attenuation were investigated in various North East Greenland, Svalbard and Siberian river mouths in 1992-1994. The amount of mineral suspensions well correlated with freshwater discharge in the case of tidal glacier bays, while such correlation in Siberian rivers and pack ice meltwater was not found. Freshwater phytoplankton species were found in Siberian estuaries only and in two other ecosystems marine and ice phytoplankton species prevailed. The light attenuation connected with freshwater discharge seems to be a key factor limiting primary production in coastal Actic waters in the summer. The amount of glacial suspensions well correlated with the salinity drop in the case of Svalbard, while Siberian river estuaries produced very turbid waters with the suspension loads not correlated to freshwater or depth.
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