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  • 1. Alexanderson, Helena
    et al.
    Hakansson, Lena
    Coastal glaciers advanced onto Jameson Land, East Greenland during the late glacial-early Holocene Milne Land Stade2014In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 33, article id 20313Article in journal (Refereed)
    Abstract [en]

    We report on Be-10 and optically stimulated luminescence ages from moraines and glaciolacustrine sediments on eastern Jameson Land, East Greenland. Sampled landforms and sediment are associated with advances of outlet glaciers from the local Liverpool Land ice cap situated in the coastal Scoresby Sund region. Previous studies have tentatively correlated these advances with the Milne Land Stade moraines, which are prominent moraine sets deposited by mountain glaciers in the inner Scoresby Sund region. Recent constraints on the formation of the outer and inner of these moraines have suggested two advances of local glaciers, one prior to or during the Younger Dryas and another during the Preboreal. In this paper, we test the correlation of the Liverpool Land glacial advance with the Milne Land Stade. Our results show that outlet glaciers from the Liverpool Land ice cap reached ice-marginal positions marked by moraines in east-facing valleys on Jameson Land sometime during late glacial-early Holocene time (ca. 13-11 Kya). This confirms the correlation of these moraines with the Milne Land Stade moraines described elsewhere in the Scoresby Sund region.

  • 2. Anderson, L G
    et al.
    Kaltin, S
    Carbon fluxes in the Arctic Ocean - potential impact by climate change2001In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 20, no 2, p. 225-232Article in journal (Refereed)
    Abstract [en]

    Because of its ice cover the central Arctic Ocean has not been considered as a sink of atmospheric carbon dioxide. With recent observations of decreasing ice cover there is the potential for an increased air-sea carbon dioxide flux. Though the sensitivity of the carbon fluxes to a climate change can at present only be speculated, we know the responses to some of the forcing, including: melting of the sea ice cover make the air-sea flux operate towards equilibrium; increased temperature of the surface water will decrease the solubility and thus the air-sea flux; and an open ocean might increase primary production through better utilization of the nutrients. The potential change in air-sea CO2 fluxes caused by different forcing as a result of climate change is quantified based on measured data. If the sea ice melts, the top 100 m water column of the Eurasian Basin has, with the present conditions, a potential to take up close to 50 g C m(-2). The freshening of the Surface water caused by a sea ice melt will increase the CO2 solubility corresponding to an uptake of similar to3 g C m(-2), while a temperature increase of 1 degreesC in the same waters will out-gas 8 g C m(-2), and a utilization of all phosphate will increase primary production by 75 g C m(-2).

  • 3.
    Anderson, Leif G.
    et al.
    Univ Gothenburg, Dept Marine Sci, SE-41296 Gothenburg, Sweden..
    Macdonald, Robie W.
    Inst Ocean Sci, Dept Fisheries & Oceans, Sidney, BC V8L 4B2, Canada..
    Observing the Arctic Ocean carbon cycle in a changing environment2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 26891Article in journal (Refereed)
    Abstract [en]

    Climate warming is especially pronounced in the Arctic, which has led to decreased sea-ice coverage and substantial permafrost thawing. These changes have a profound impact on the carbon cycle that directly affects the air-sea exchange of carbon dioxide (CO2), possibly leading to substantial feedback on atmospheric CO2 concentration. Several recent studies have indicated such feedback but the future quantitative impact is very uncertain. To minimize these uncertainties, there is a need for extensive field studies in order to achieve both a better process understanding as well as to detect probable trends in these processes. In this contribution, we describe a number of processes that have been reported to be impacted by climate change and suggest a coordinated international observational programme for their study.

  • 4.
    Divine, Dmitry
    et al.
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway.;Univ Tromso, Fac Sci & Technol, Dept Math & Stat, NO-9037 Tromso, Norway..
    Isaksson, Elisabeth
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway..
    Martma, Tonu
    Tallinn Univ Technol, Inst Geol, EE-19086 Tallinn, Estonia..
    Meijer, Harro A. J.
    Univ Groningen, Ctr Isotope Res, NL-9747 AG Groningen, Netherlands..
    Moore, John
    Univ Lapland, Arctic Ctr, FI-96101 Rovaniemi, Finland..
    Pohjola, Veijo
    Uppsala Univ, Dept Earth Sci, SE-75236 Uppsala, Sweden..
    van de Wal, Roderik S. W.
    Univ Utrecht, Inst Marine & Atmospher Res Utrecht, NL-3584 CC Utrecht, Netherlands..
    Godtliebsen, Fred
    Univ Tromso, Fac Sci & Technol, Dept Math & Stat, NO-9037 Tromso, Norway..
    Thousand years of winter surface air temperature variations in Svalbard and northern Norway reconstructed from ice-core data2011In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 30, article id 7379Article in journal (Refereed)
    Abstract [en]

    Two isotopic ice core records from western Svalbard are calibrated to reconstruct more than 1000 years of past winter surface air temperature variations in Longyearbyen, Svalbard, and Vardo, northern Norway. Analysis of the derived reconstructions suggests that the climate evolution of the last millennium in these study areas comprises three major sub-periods. The cooling stage in Svalbard (ca. 800-1800) is characterized by a progressive winter cooling of approximately 0.9 degrees C century(-1) (0.38 degrees C century(-1) for Vardo) and a lack of distinct signs of abrupt climate transitions. This makes it difficult to associate the onset of the Little Ice Age in Svalbard with any particular time period. During the 1800s, which according to our results was the coldest century in Svalbard, the winter cooling associated with the Little Ice Age was on the order of 4 degrees C (1.3 degrees C for Vardo) compared to the 1900s. The rapid warming that commenced at the beginning of the 20th century was accompanied by a parallel decline in sea-ice extent in the study area. However, both the reconstructed winter temperatures as well as indirect indicators of summer temperatures suggest the Medieval period before the 1200s was at least as warm as at the end of the 1990s in Svalbard.

  • 5. Eggertsson, Ólafur
    Driftwood as an indicator of relative changes in the influx of Arctic and Anlantic water into the coastal areas of Svalbard1994In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 13, no 2, p. 209-218Article in journal (Refereed)
    Abstract [en]
    A total of 276 driftwood samples from Wijdefjorden on the northern coast of Spitsbergen were den-drochronologically analysed and compared with results from a similar study on driftwood from Isfjorden. The composition and origin of the driftwood from the two places differ. Whereas Larix is almost absent in the Isfjorden driftwood, it comprises 25% of the Wijdefjorden collection. The Isfjorden driftwood has its main origin in the White Sea region and the dates of the driftwood concentrate around the period from 1950 to 1979, with only a few dates from the period 1910 to 1950. The Wijdefjorden driftwood has two main origins: Siberia and the White Sea region. The dates of the White Sea components of the Wijdefjorden driftwood are concentrated mainly in the period 1910-1950. The dates of the Siberian (Yenisey) components of the Wijdefjorden driftwood are concentrated in the period 1950–1979. It can be argued that during the time period from ca. 1910 to 1950 the activity of a warm northerly flowing current along the western coast of Spitsbergen was stronger, transporting White Sea driftwood all the way to the Wijdefjorden area. However, after ca. 1950 the input of White Sea driftwood decreased, and the relative importance of the Siberian component increased. These results fit well with the climatic records from Svalbard, showing a warm regime during the first half of this century due to increased activity of the warm West Spitsbergen Current along the western coast of Spitsbergen. After ca. 1950, the influx of Atlantic Water became weaker, the climate became colder and the relative occurrences of Siberian driftwood transported by the Transpolar Current increased on the northern coast of the Svalbard archipelago.
  • 6.
    Hanslik, Daniela
    et al.
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Löwemark, Ludvig
    Natl Taiwan Univ, Dept Geosci, Taipei 106, Taiwan.;Alfred Wegener Inst Polar & Marine Res, Climate Sci Div, DE-27570 Bremerhaven, Germany..
    Jakobsson, Martin
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Biogenic and detrital-rich intervals in central Arctic Ocean cores identified using x-ray fluorescence scanning2013In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 32, article id 18386Article in journal (Refereed)
    Abstract [en]

    X-ray fluorescence (XRF) scanning of sediment cores from the Lomonosov Ridge and the Morris Jesup Rise reveals a distinct pattern of Ca intensity peaks through Marine Isotope Stages (MIS) 1 to 7. Downcore of MIS 7, the Ca signal is more irregular and near the detection limit. Virtually all major peaks in Ca coincide with a high abundance of calcareous microfossils; this is particularly conspicuous in the cores from the central Arctic Ocean. However, the recorded Ca signal is generally caused by a combination of biogenic and detrital carbonate, and in areas influenced by input from the Canadian Arctic, detrital carbonates may effectively mask the foraminiferal carbonates. Despite this, there is a strong correlation between XRF-detected Ca content and foraminiferal abundance. We propose that in the Arctic Ocean north of Greenland a common palaeoceanographic mechanism is controlling Ca-rich ice-rafted debris (IRD) and foraminiferal abundance. Previous studies have shown that glacial periods are characterized by foraminfer-barren sediments. This implies that the Ca-rich IRD intervals with abundant foraminifera were most likely deposited during interglacial periods when glaciers left in the Canadian Arctic Archipelago were still active and delivered a large amount of icebergs. At the same time, conditions were favourable for planktic foraminifera, resulting in a strong covariance between these proxies. Therefore, we suggest that the XRF scanner's capability to efficiently map Ca concentrations in sediment cores makes it possible to systematically examine large numbers of cores from different regions to investigate the palaeoceanographic reasons for the calcareous microfossils' spatial and temporal variability.

  • 7.
    Jakobsson, Martin
    et al.
    Stockholm Univ, Dept Geol & Geochem, SE-10691 Stockholm, Sweden..
    Spielhagen, Robert F.
    Acad Sci Human & Literature, DE-55131 Mainz, Germany.;Univ Kiel, Leibniz Inst Marine Sci, DE-24148 Kiel, Germany..
    Thiede, Joern
    Alfred Wegener Inst Polar & Marine Res, DE-27568 Bremerhaven, Germany.;Univ Copenhagen, Dept Geog & Geol, DK-1350 Copenhagen, Denmark..
    Andreasen, Claus
    Greenland Natl Museum & Archives, DK-3900 Nuuk, Greenland..
    Hall, Brenda
    Univ Maine, Bryand Global Sci Ctr, Dept Earth Sci, Orono, ME 04469 USA.;Univ Maine, Climate Change Inst, Orono, ME 04469 USA..
    Ingolfsson, Olafur
    Univ Iceland, Dept Earth Sci, IS-101 Reykjavik, Iceland..
    Kjaer, Kurt H.
    Univ Copenhagen, Nat Hist Museum, DK-1350 Copenhagen K, Denmark..
    van Kolfschoten, Thijs
    Leiden Univ, Fac Archaeol, NL-2311 BE Leiden, Netherlands..
    Krinner, Gerhard
    Natl Ctr Sci Res, Lab Glaciol & Geophys Environm, FR-38402 St Martin Dheres, France..
    Long, Antony
    Univ Durham, Dept Geog, Durham DH1 3LE, England..
    Lunkka, Juha-Pekka
    Univ Oulu, Inst Geosci, FI-90014 Oulu, Finland..
    Subetto, Dmitry
    Alexander Herzen State Pedag Univ Russia, Dept Geog, RU-191186 St Petersburg, Russia..
    Svendsen, John Inge
    Univ Bergen, Dept Earth Sci, NO-5007 Bergen, Norway.;Univ Bergen, Bjerknes Ctr Climate Res, NO-5007 Bergen, Norway..
    Foreword to the special issue: Arctic Palaeoclimate and its Extremes (APEX)2008In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 27, no 2, p. 97-104Article in journal (Other academic)
  • 8.
    Kuhnel, Rafael
    et al.
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway.;Univ Oslo, Fac Math & Nat Sci, Dept Geosci, NO-0315 Oslo, Norway..
    Bjorkman, Mats P.
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway.;Univ Oslo, Fac Math & Nat Sci, Dept Geosci, NO-0315 Oslo, Norway..
    Vega, Carmen P.
    Uppsala Univ, Dept Earth Sci, SE-75236 Uppsala, Sweden..
    Hodson, Andy
    Univ Sheffield, Dept Geog, Sheffield S10 2TN, S Yorkshire, England..
    Isaksson, Elisabeth
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway..
    Ström, Johan
    Stockholm Univ, Dept Appl Environm Sci, SE-11418 Stockholm, Sweden..
    Reactive nitrogen and sulphate wet deposition at Zeppelin Station, Ny-Alesund, Svalbard2013In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 32, article id UNSP 19136Article in journal (Refereed)
    Abstract [en]

    As a potent fertilizer, reactive nitrogen plays an important role in Arctic ecosystems. Since the Arctic is a nutrient-limited environment, changes in nitrogen deposition can have severe impacts on local ecosystems. To quantify the amount of nitrogen deposited through snow and rain events, precipitation sampling was performed at Zeppelin Station, Svalbard, from November 2009 until May 2011. The samples were analysed for NO3-; nss-SO42- and NH4+ concentrations, and the deposition of single precipitation events was calculated using precipitation measurements taken at nearby Ny-Alesund. The majority of observed events showed concentrations ranging from 0.01 to 0.1 mg L-1 N for NO3- and NH4+ and from 0.02 to 0.3 mg L-1 S for nss-SO42-. The majority of calculated depositions ranged from 0.01 to 0.1 mg m(-2) N for NO3- and NH4+ and from 0.02 to 0.3 mg m(-2) S for nss-SO42-. The budget was controlled by strong deposition events, caused by long-lasting precipitation episodes that lasted for several days and which had raised concentrations of nitrogen and sulphur. Three future scenarios of increasing precipitation in the Arctic were considered. The results showed that deposition is mainly controlled by the amount of precipitation, which leads to the conclusion that increased precipitation might cause increases in deposition of the same magnitude.

  • 9. Kylin, Henrik
    et al.
    Hammar, Johan
    Mowrer, Jacques
    Bouwman, Henk
    Edelstam, Carl
    Olsson, Mats
    Jensen, Soeren
    Persistent organic pollutants in biota samples collected during the Ymer-80 expedition to the Arctic2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34Article in journal (Refereed)
    Abstract [en]

    During the 1980 expedition to the Arctic with the icebreaker Ymer, a number of vertebrate species were sampled for determination of persistent organic pollutants. Samples of Arctic char (Salvelinus alpinus, n = 34), glaucous gull (Larus hyperboreus, n = 8), common eider (Somateria mollissima, n = 10), Brunnich’s guillemot (Uria lomvia, n = 9), ringed seal (Pusa hispida, n = 2) and polar bear (Ursus maritimus, n = 2) were collected. With the exception of Brunnich’s guillemot, there was a marked contamination difference of birds from western as compared to eastern/northern Svalbard. Samples in the west contained a larger number of polychlorinated biphenyl (PCB) congeners and also polychlorinated terphenyls, indicating local sources. Brunnich’s guillemots had similar pollutant concentrations in the west and east/north; possibly younger birds were sampled in the west. In Arctic char, pollutant profiles from lake Linnevatn (n = 5), the lake closest to the main economic activities in Svalbard, were similar to profiles in Arctic char from the Shetland Islands (n = 5), but differed from lakes to the north and east in Svalbard (n = 30). Arctic char samples had higher concentrations of hexachlorocyclohexanes (HCHs) than the marine species of birds and mammals, possibly due to accumulation via snowmelt. Compared to the Baltic Sea, comparable species collected in Svalbard had lower concentrations of PCB and dichlorodiphenyltrichloroethane (DDT), but similar concentrations indicating long-range transport of hexachlorobenzene, HCHs and cyclodiene pesticides. In samples collected in Svalbard in 1971, the concentrations of PCB and DDT in Brunnich’s guillemot (n = 7), glaucous gull (n = 2) and polar bear (n = 2) were similar to the concentrations found in 1980.

  • 10.
    Lund-Hansen, Lars Chresten
    et al.
    Aarhus Univ, Dept Biosci, Aquat Biol, DK-8000 Aarhus C, Denmark.;Aarhus Univ, Arctic Res Ctr, DK-8000 Aarhus C, Denmark..
    Markager, Stiig
    Aarhus Univ, Marine Ecol, Dept Biosci, DK-4000 Roskilde, Denmark..
    Hancke, Kasper
    Univ So Denmark, Dept Biol, Nordic Ctr Earth Evolut, DK-5230 Odense M, Denmark..
    Stratmann, Tanja
    Royal Netherlands Inst Sea Res, Ecosyst Studies, NL-4401 NT Yerseke, Netherlands..
    Rysgaard, Søren
    Aarhus Univ, Arctic Res Ctr, DK-8000 Aarhus C, Denmark.;Greenland Inst Nat Resources, Greenland Climate Res Ctr, DK-3900 Nuuk Greenland, Denmark.;Univ Manitoba, Dept Geog & Environm, Ctr Earth Observat Sci, Winnipeg, MB R3T 2N2, Canada..
    Ramiov, Hans
    Roskilde Univ, Dept Sci Syst & Models, DK-4000 Roskilde, Denmark..
    Sorrell, Brian K.
    Aarhus Univ, Dept Biosci, Aquat Biol, DK-8000 Aarhus C, Denmark.;Aarhus Univ, Arctic Res Ctr, DK-8000 Aarhus C, Denmark..
    Effects of sea-ice light attenuation and CDOM absorption in the water below the Eurasian sector of central Arctic Ocean (>88°N)2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 23978Article in journal (Refereed)
    Abstract [en]

    This is a study of the optical, physical and biological parameters of sea ice and the water below it at stations (n = 25) in the central (> 88 degrees N) Eurasian sector of the Arctic Ocean during the summer 2012 record low sea-ice minimum extent. Results show that photosynthetically active radiation (PAR) transmittance of the ice was low (0.09) and apparently related to a high degree of backscattering by air-filled brine channels left by brine draining. The under-ice PAR was also low (8.4 +/- 4.5 SD mu mol photons m(-2) s(-1)) and partly related to the low transmittance. There were no significant differences in multi-year and first-year PAR transmittances. In spite of this low under-ice PAR, only 3% of the transmitted PAR through the ice was absorbed by phytoplankton in the water. On average, chlorophyll-a concentrations were low (0.34 +/- 0.69 SD mg chl-a m(-3)) in the water compared to the high (a(375) = 0.52 m(-1)) coloured dissolved organic matter (CDOM) absorption coefficient with a strong terrestrial optical signature. Two distinct clusters of stations with waters of Pacific and North Atlantic origin were identified based on significant differences in temperature, salinity and CDOM absorption coefficient between water masses. The under-ice light field for bare ice was parameterized as follows: I-z = I-o(1 -0.55)*(0.09)* exp ((-0.17*z)).

  • 11. Moller, Per
    et al.
    Fedorov, Grigorij
    Pavlov, Maxim
    Seidenkrantz, Marit-Solveig
    Sparrenbom, Charlotte
    Glacial and palaeoenvironmental history of the Cape Chelyuskin area, Arctic Russia2008In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 27, no 2, p. 222-248Article in journal (Refereed)
    Abstract [en]

    Quaternary glacial stratigraphy and relative sea-level changes reveal at least two glacial expansions over the Chelyuskin Peninsula, bordering the Kara Sea at about 77 degrees N in the Russian Arctic, as indicated from tills interbedded with marine sediments, exposed in stratigraphic superposition, and from raised-beach sequences mapped to altitudes of at least up to ca. 80 m a.s.l. Chronological control is provided by accelerator mass spectrometry (14)C dating, electron-spin resonance and optically stimulated luminescence geochronology. Major glaciations, followed by deglaciation and marine inundation, occurred during marine oxygen isotope stages 6-5e (MIS 6-5e) and stages MIS 5d-5c. These glacial sediments overlie marine sediments of Pliocene age, which are draped by fluvial sediment of a pre-Saalian age, thereby forming palaeovalley/basin fills in the post-Cretaceous topography. Till fabrics and glacial tectonics record expansions of local ice caps exclusively, suggesting wet-based ice cap advance, followed by cold-based regional ice-sheet expansion. Local ice caps over highland sites along the perimeter of the shallow Kara Sea, including the Byrranga Mountains and the Severnaya Zemlya archipelago, appear to have repeatedly fostered initiation of a large Kara Sea ice sheet, with the exception of the Last Glacial Maximum (MIS 2), when Kara Sea ice neither impacted the Chelyuskin Peninsula nor Severnaya Zemlya, and barely touched the northern coastal areas of the Taymyr Peninsula.

  • 12.
    O'Regan, Matt
    et al.
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Sellen, Emma
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Jakobsson, Martin
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Middle to late Quaternary grain size variations and sea-ice rafting on the Lomonosov Ridge2014In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 33, article id 23672Article in journal (Refereed)
    Abstract [en]

    Sea ice and icebergs are the dominant transport agents for sand-sized material to the central Arctic Ocean. However, few studies have investigated concurrent changes in the silt-sized fraction of Arctic sediments. Here we present an analysis of the coarse fraction content and silt grain size composition from middle and late Quaternary sediments recovered from the Lomonosov Ridge, in the central Arctic Ocean. A significant shift in the grain size record occurs at the marine isotope stage (MIS) 6/7 boundary, where larger amplitude variability in the sand fraction is seen in glacial and stadial periods. Below the MIS6/7 boundary, variations in the coarse fraction content are less pronounced, but prominent changes in the silt size fraction appear to define glacial and interglacial periods. Throughout the record, the percent weight of sortable silt in the fine fraction (SS % wt(fines)), sortable silt mean size, and coarse silt content all increase as the >63 mu m % wt content increases. This is consistent with observations of grain size spectra obtained from modern sea-ice samples, and indicates a strong overprint from sea ice on the silt distribution. The mechanism by which this sea-ice signal is preserved in the sediments across glacial and interglacial periods remains unclear. We suggest that the coarsening of silt-sized material during glacial periods could be attributed to either the entrainment of larger size fractions during suspension/anchor ice formation when sea levels are lowered, or diminished input and advection of fine fraction material during glacial periods.

  • 13.
    Thompson, Bijoy
    et al.
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Jakobsson, Martin
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Nilsson, Johan
    Stockholm Univ, Dept Meteorol, SE-10691 Stockholm, Sweden..
    Nycander, Jonas
    Stockholm Univ, Dept Meteorol, SE-10691 Stockholm, Sweden..
    Doos, Kristofer
    Stockholm Univ, Dept Meteorol, SE-10691 Stockholm, Sweden..
    A model study of the first ventilated regime of the Arctic Ocean during the early Miocene2012In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 31, article id 10859Article in journal (Refereed)
    Abstract [en]

    The tectonic opening of Fram Strait during the Neogene was a significant geological event that transferred the Arctic Ocean from a poorly ventilated enclosed basin, with weak exchange with the North Atlantic, to a fully ventilated "ocean stage''. Previous tectonic and physical oceanographic analyses suggest that the early Miocene Fram Strait was likely several times narrower and less than half as deep as the present-day 400 km wide and 2550 m deep strait. Here we use an ocean general circulation model with a passive age tracer included to further address the effect of the Fram Strait opening on the early Miocene Arctic Ocean circulation. The model tracer age exhibits strong spatial gradient between the two major Arctic Ocean deep basins: the Eurasian and Amerasian basins. There is a two-layer stratification and the exchange flow through Fram Strait shows a bi-layer structure with a low salinity outflow from the Arctic confined to a relatively thin upper layer and a saline inflow from the North Atlantic below. Our study suggests that although Fram Strait was significantly narrower and shallower during early Miocene, and the ventilation mechanism quite different in our model, the estimated ventilation rates are comparable to the chemical tracer estimates in the present-day Arctic Ocean. Since we achieved ventilation of the Arctic Ocean with a prescribed Fram Strait width of 100 km and sill depth of 1000 m, ventilation may have preceded the timing of a full ocean depth connection between the Arctic Ocean and North Atlantic established through seafloor spreading and the development of the Lena Trough.

  • 14.
    Vega, Carmen P.
    et al.
    Uppsala Univ, Dept Earth Sci, SE-76236 Uppsala, Sweden..
    Bjorkman, Mats P.
    Univ Gothenburg, Dept Earth Sci, SE-40530 Gothenburg, Sweden..
    Pohjola, Veijo A.
    Uppsala Univ, Dept Earth Sci, SE-76236 Uppsala, Sweden..
    Isaksson, Elisabeth
    Norwegian Polar Res Inst, Fram Ctr, NO-9296 Tromso, Norway..
    Pettersson, Rickard
    Uppsala Univ, Dept Earth Sci, SE-76236 Uppsala, Sweden..
    Martma, Tonu
    Tallinn Univ Technol, Inst Geol, EE-19086 Tallinn, Estonia..
    Marca, Alina
    Univ E Anglia, Sch Environm Sci, Ctr Ocean & Atmospher Sci, Norwich NR4 7TJ, Norfolk, England..
    Kaiser, Jan
    Univ E Anglia, Sch Environm Sci, Ctr Ocean & Atmospher Sci, Norwich NR4 7TJ, Norfolk, England..
    Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 23246Article, review/survey (Refereed)
    Abstract [en]

    Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited.

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  • rtf