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  • Articles  (9)
  • Arctic
  • Electronic structure and strongly correlated systems
  • 2000-2004  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Holocene environmental history of thermokarst lakes on Richards Island, Northwest Territories, Canada: Theocamoebians as paleolimnological indicators (2000)
    Springer
    Journal of paleolimnology 23 (2000), S. 261-283 
    Details
    ISSN: 1573-0417
    Keywords: thecamoebians ; paleolimnology ; Holocene ; thermokarst lakes ; Arctic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Richards Island, Northwest Territories, Canada, is characterized by thermokarst lakes which record Holocene limnological change. This study is the first report of thecamoebian assemblages and continuous annual lake water temperatures from these Arctic lakes. Ecological environments on Richards Island are influenced by a climatic gradient resulting from the contrasting influences of the cold Beaufort Sea to the north and the warm waters of the Mackenzie Delta to the east and west. This climatic gradient in turn influences modern thecamoebian assemblages, and is an indication of the complexity involved in interpreting past conditions from core material in this area. Population abundance and species diversity of thecamoebian assemblages on Richards Island are not significantly different from those reported from temperate and semi-tropical latitudes. However, certain assemblage characteristics, such as large and coarse agglutinated tests, dominance of assemblages by one or two species and low morphological variation are interpreted to be diagnostic of Arctic conditions. Thecamoebian assemblages in core material from the area indicate that the local paleolimnological conditions may have changed within the last 3 ka, and this is unrecorded in previously reported pollen data. Paleoenvironmental interpretations in a permafrost landscape have to take into account morphological instability of thermokarst lakes, which can be the cause of paleolimnological and consequently faunal change. In this area ecosystem development is clearly related to geomorphology and local climatic effects and is not exclusively controlled by regional climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008184522637
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  • 2
    Electronic Resource
    Electronic Resource
    Holocene lake sediment records of Arctic hydrology (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 1-13 
    Details
    ISSN: 1573-0417
    Keywords: Arctic ; Holocene ; paleohydrology ; paleolimnology ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Although paleoclimatic research in the Arctic has most often focused on variations in temperature, the Arctic has also experienced changes in hydrologic balance. Changes in Arctic precipitation and evaporation rates affects soils, permafrost, lakes, wetlands, rivers, ice and vegetation. Changes in Arctic soils, permafrost, runoff, and vegetation can influence global climate by changing atmospheric methane and carbon dioxide concentrations, thermohaline circulation, and high latitude albedo. Documenting past variations in Arctic hydrological conditions is important for understanding Arctic climate and the potential response and role of the Arctic in regards to future climate change. Methods for reconstructing past changes in Arctic hydrology from the stratigraphic, isotopic, geochemical and fossil records of lake sediments are being developed, refined and applied in a number of regions. These records suggest that hydrological variations in the Arctic have been regionally asynchronous, reflecting the impacts of different forcing factors including orbitally controlled insolation changes, changes in geography related to coastal emergence, ocean currents, sea ice extent, and atmospheric circulation. Despite considerable progress, much work remains to be done on the development of paleohydrological proxies and their application to the Arctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008100714795
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  • 3
    Electronic Resource
    Electronic Resource
    GCM-simulated hydrology in the Arctic duringn the past 21,000 years (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 15-28 
    Details
    ISSN: 1573-0417
    Keywords: Last Glacial Maximum ; Arctic ; paleoclimatology ; Holocene ; climate modeling ; hydrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The Paleoclimates from Arctic Lakes and Estuaries (PALE) project has chosen to conduct high resolution data-model comparisons for the Arctic region at 21 and 10 (calendar) ka BP. The model simulations for 21, 10, and 0 ka BP were conducted with the GENESIS 2.0 GCM. The 10 ka BP simulation was coupled to the EVE vegetation model. The primary boundary conditions differing from present at 21 ka BP were the northern hemisphere ice sheets and lower CO2, and at 10 ka BP were the orbital insolation and smaller northern hemisphere ice sheets. The purpose of this article is to discuss the hydrological consequences of these simulations. At the Last Glacial Maximum (21 ka BP) the large ice sheets over North America and Eurasia and the lower CO2 levels produced a colder climate than present, with less precipitation throughout the Arctic, except where circulation was altered by the ice sheets. At 10 ka BP greater summer insolation resulted in a warmer and wetter Beringia, but conditions remained cold and dry in the north Atlantic sector, in the vicinity of the remnant ice sheets. Less winter insolation at 10 ka BP resulted in colder and drier conditions throughout the Arctic. Precipitation - evaporation generally correlated with precipitation except where changes in the surface type (ice sheets, vegetation at 10 ka BP, or sea level at 21 ka BP) caused large changes in the evaporation rate. The primary hydrological differences (from present) at 21 and 10 ka BP correlated with the temperature differences, which were a direct result of the large-scale boundary condition changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008161631633
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  • 4
    Electronic Resource
    Electronic Resource
    The Svalbard western coast: site of baseline geochemistry and incipient contamination (2000)
    Springer
    Environmental geology 39 (2000), S. 816-822 
    Details
    ISSN: 1432-0495
    Keywords: Key words Heavy metals ; Arctic ; Isfjorden ; Sediment ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Potentially toxic metals tracked by the Arctic Monitoring and Assessment Program were analysed in sediments from the Svalbard western coastal zone. These include As and Hg found as contaminants in other Arctic seas as well as other elements (e.g. Pb, V, Cu, Zn, Cr, Ni). Svalbard shelf sediments contain average values of 12 ppm As, 12 ppm Pb, 56 ppb Hg and 114 ppm V. These values increase in Isfjorden sediments to 15 ppm As, 28 ppm Pb, 99 ppb Hg and 210 ppm V. Cluster analysis yields a major cluster that is likely related to clay minerals (Al, K, Ti, Mg) and sorption onto them of transition (Cu, V, Cr, Sc) and other elements (Pb, Rb). A second significant cluster includes Ca, Sr and plagioclase. The Svalbard western shelf is a natural geochemical environment. The possible incipient contamination of fjord sediments by As, Pb, Hg and V should be evaluated for possible links to anthropogenic sources. If links are found, remediation must be used to stop the input and preserve a pristine Svalbard fjord environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050498
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  • 5
    Electronic Resource
    Electronic Resource
    Nitrogen and phosphorus removal by high latitude mat-forming cyanobacteria for potential use in tertiary wastewater treatment (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 105-112 
    Details
    ISSN: 1573-5176
    Keywords: Antarctica ; Arctic ; cyanobacteria ; nutrients ; Oscillatoria ; Phormidium subfuscum ; Phormidium bohneri ; Schizothrix calcicola ; tertiary treatment ; wastewater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of a program to develop biological wastewatertreatment systems for cold climate areas four strainsof filamentous, mat-forming cyanobacteria isolatedfrom Arctic and Antarctic environments were evaluatedfor their nutrient stripping and growth capabilities. A tropical strain, Phormidium bohneri, known forits excellent performance in wastewater treatment, wasused as a comparison. Experiments were done inartificial media under controlled batch cultureconditions to avoid interactions with indigenousmicroorganisms such as bacteria and protozoa. Theculture medium simulated real effluents containinghigh concentrations of nitrate and phosphate.Temperatures (5, 15 and 25°C) and irradiances(80, 210, 350, 640 and 1470 µmol photon m-2s-1) wereselected according to situations encountered in avariety of field conditions. For all irradiancelevels, growth was satisfactory at 15 and 25 °C,but limited at 5 °C. At 25 °C a satisfactory nitrogen removal rate (3.5and 4.0 mg N L-1d-1) was obtained forone polar strain (Phormidium tenue) and thecontrol P. bohneri. At 15 °C, the bestnitrogen removal rate (3.5 mg N L-1d-1)was measured with P. bohneri while the best ratefor the polar strains was around 2.3 mg NL-1d-1. At 15 °C, a phosphorusremoval rate of 0.6 mg P L-1d-1 wasobtained with P. bohneri and polar strains P. tenue and Oscillatoria O-210. Nitrogen(NO3 -) and phosphorus (PO4 3-)uptake rates increased as a function of irradianceover the range 80 to 350 μmolphoton m-2s-1. Our results indicate thattertiary biological wastewater treatment at lowtemperatures (5 °C) cannot be anticipated withthe polar strains tested, because they arepsychrotrophic rather than psychrophilic and thus growtoo slowly under conditions of extreme cold. However, it appears that these cyanobacteria would beuseful for wastewater treatment at moderately cooltemperatures (c. 15 °C), which are commonduring spring and fall in northern climates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008168128654
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of temperature and nitrogen source on growth and nitrogen uptake of two polar-desert species, Saxifraga caespitosa and Cerastium alpinum (2000)
    Springer
    Plant and soil 227 (2000), S. 139-148 
    Details
    ISSN: 1573-5036
    Keywords: Arctic ; Cerastium alpinum ; nitrogen source ; nitrogen-uptake ; organic N ; polar-desert plants ; Saxifraga caespitosa ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polar-desert plants experience low average air temperatures during their short growing season (4–8 °C mean July temperature). In addition, low availability of inorganic nitrogen in the soil may also limit plant growth. Our goals were to elucidate which N sources can be acquired by polar-desert plants, and how growth and N-uptake are affected by low growth temperatures. We compared rates of N-uptake and increases in mass and leaf area of two polar-desert species (Cerastium alpinum L. and Saxifraga caespitosa L.) over a period of 3 weeks when grown at two temperatures (6 °C vs. 15 °C) and supplied with either glycine, NH4 + or NO3 −. At 15 °C, plants at least doubled their leaf area, whereas there was no change in leaf area at 6 °C. Measured mean N-uptake rates varied between 0.5 nmol g−1 root DM s−1 on glycine at 15 °C and 7.5 nmol g−1 root DM s−1 on NH4 + at 15 °C. Uptake rates based upon increases in mass and tissue N concentrations showed that plants had a lower N-uptake rate at 6 °C, regardless of N source or species. We conclude that these polar-desert plants can use all three N sources to increase their leaf area and support flowering when grown at 15 °C. Based upon short-term (8 h) uptake experiments, we also conclude that the short-term capacity to take up inorganic or organic N is not reduced by low temperature (6 °C). However, net N-uptake integrated over a three-week period is severely reduced at 6 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026528830228
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  • 7
    Electronic Resource
    Electronic Resource
    Is the Arctic Surface Layer a Source and Sink of NOx in Winter/Spring? (2000)
    Springer
    Journal of atmospheric chemistry 36 (2000), S. 1-22 
    Details
    ISSN: 1573-0662
    Keywords: active nitrogen ; ozone ; radicals ; snow chemistry ; Arctic ; surface layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Measurements of NOx (NO +NO2) and the sum of reactive nitrogenconstituents, NOy, were made near the surface atAlert (82.5°N), Canada during March and April1998. In early March when solar insolation was absentor very low, NOx mixing ratios were frequentlynear zero. After polar sunrise when the sun was abovethe horizon for much or all of the day a diurnalvariation in NOx and NOy was observed withamplitudes as large as 30–40 pptv. The source ofactive nitrogen is attributed to release from the snowsurface by a process that is apparently sensitized bysunlight. If the source from the snowpack is a largescale feature of the Arctic then the diurnal trendsalso require a competing process for removal to thesurface. From the diurnal change in the NO/NO2ratio, mid-April mixing ratios for the sum of peroxyand halogen oxide radicals of ≤10 pptv werederived for periods when ozone mixing ratios were inthe normal range of 30–50 ppbv. Mid-day ozoneproduction and loss rates with the active nitrogensource were estimated to be ∼1–2 ppbv/day and in nearbalance. NOy mixing ratios which averaged only295±66 pptv do not support a large accumulation inthe high Arctic surface layer in the winter and springof 1998. The small abundance of NOy relative tothe elevated mixing ratios of other long-livedanthropogenic constituents requires that reactivenitrogen be removed to the surface during transport toor during residence within the high Arctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006301029874
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  • 8
    Electronic Resource
    Electronic Resource
    Annual growth of the cockle Clinocardium ciliatum in the Norwegian Arctic (Svalbard area) (2000)
    Springer
    Hydrobiologia 440 (2000), S. 331-338 
    Details
    ISSN: 1573-5117
    Keywords: Bivalvia ; growth ; Arctic ; Clinocardium ciliatum ; Svalbard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Svalbard Islands are influenced by warm Atlantic water in the south and west, and cold Arctic water in the east. Ice cover, and hence the location of the highly productive marginal ice zone, varies both intra and interannually. Part of the primary production accumulates on the bottom and is utilized by the benthos. In this study, the annual growth of the cockle Clinocardium ciliatum (Fabricius, 1780) from three sites in Svalbard waters is reported. Moffen, the site in the north (80° 01′ N, 13° 48′ E) is located in the northernmost areas influenced by Atlantic water. The Storfjorden site (77° 10′ N, 20° 09′ E) is situated in cold Arctic water masses, and the Bear Island site (74° 50′ N, 18° 54′ E) is in the Polar front area where Atlantic and Arctic water masses meet. Annual growth of cockles was analysed retrospectively by measuring external growth increments, which gave annual growth records from the 1970s to 1996. Shell height for age for different year classes was highest at the Storfjorden site, and lowest at Bear Island. Periods of high growth occurred at Storfjorden and Bear Island during the 1980s while the beginning of 1990s was characterized by low growth. At Moffen, growth was more variable between single years. Several factors are influencing the growth of C. ciliatum in the Svalbard area and growth cannot be coupled to only one environmental factor like ice cover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004108219117
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  • 9
    Electronic Resource
    Electronic Resource
    Feeding Ecology and the Concentration of Organochlorines in Glaucous Gulls (2000)
    Springer
    Ecotoxicology 9 (2000), S. 179-186 
    Details
    ISSN: 1573-3017
    Keywords: Arctic ; organochlorines ; Larido ; gulls ; feeding ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We investigated the blood concentrations of organochlorines (OCs) and the diet of glaucous gulls Larus hyperboreus breeding in two neighbouring areas at Bear Island in the Barents Sea, north-eastern Atlantic. One area was situated on the edge of the large seabird cliff, about 100–150 m above sea level. The second area was about 1–2 km from the seabird cliff, and 10–50 m above sea level. In both 1997 and 1998 there were significant differences between the breeding areas for five OCs (HCB, HCH, Oxychlordan, DDE and PCB) measured, with the birds breeding on the cliff having higher levels. These differences were accompanied by a difference in diet between the areas. Birds in the former area had at least four times higher intake of guillemot Uria spp. eggs, while the birds near sea level seemed to have a much higher intake of fish. This study demonstrates the importance of feeding ecology for the distribution of OCs within populations. The results have important implications for the establishment of monitoring programs for OC contamination of the glaucous gull in the Arctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008938603257
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