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  • 1. Abrahamsson, Katarina
    The biogeochemical cycle of organo-halogens in the High Arctic and along the Northwest Passage2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , s. 82 - 84Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 2. Adler, Ruth E.
    et al.
    Polyak, Leonid
    Ortiz, Joseph D.
    Kaufman, Darrell S.
    Channell, James E.T.
    Chuang Xuan,
    Grottoli, Andréa G.
    Sellén, Emma
    Crawford, Kevin A.
    Sediment record from the western Arctic Ocean with an improved Late Quaternary age resolution: HOTRAX core HLY0503-8JPC, Mendeleev Ridge2009Ingår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 68, nr 1-2, s. 18-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sediment core HLY0503-8JPC raised by the HOTRAX'05 expedition from the Mendeleev Ridge was analyzed for multiple lithological, paleontological, and stable-isotopic proxies to reconstruct paleoceanographic conditions in the western Arctic Ocean during the Late Quaternary. The core, extensively sampled in the upper 5 m, reveals pronounced changes in sedimentary environments during the ca. 250 kyr interval encompassing Marine Isotopic Stages (MIS) 1 to 7. An estimated average resolution of 500 yr/sample, at least for the last glacial cycle including the last interglacial, provides more detail than seen in other sedimentary records from the western Arctic Ocean. The age control is provided by 14C and amino acid racemization measurements on planktonic foraminifers and correlations with the stratigraphy developed for the central Lomonosov Ridge and with glacial events at the Eurasian Arctic margin. Cyclic variations in lithology combined with foraminiferal abundance and stable-isotopic composition indicate profound changes in hydrographic and depositional environments between interglacial-type and glacial-type periods apparently reflecting a combination of 100-kyr and precessional time scales. This periodicity is complicated by abrupt iceberg- and/or meltwater-discharge events with variable (Laurentide vs. Eurasian) provenance. The proxy record from the interval identified as the last interglacial (MIS 5e), which may aid in understanding the future state of the Arctic Ocean, indicates low ice conditions and possibly enhanced stratification of the water column.

  • 3. Alerstam, Thomas
    Bird migration and species diversity under polar conditions: the Siberian - American migration systems2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , s. 116 - 120Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 4. Alerstam, Thomas
    et al.
    Bäckman, Johan
    Gudmundsson, Gudmundur A.
    Hedenström, Anders
    Henningsson, Sara S.
    Karlsson, Håkan
    Rosen, Mikael
    Strandberg, Roine
    A polar system of intercontinental bird migration2007Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 274, nr 1625, s. 2523-2530Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Studies of birdmigration in the Beringia region of Alaska and eastern Siberia are of special interest for revealing the importance of bird migration between Eurasia and North America, for evaluating orientation principles used by the birds at polar latitudes and for understanding the evolutionary implications of intercontinental migratory connectivity among birds as well as their parasites. We used tracking radar placed onboard the ice-breaker Oden to register bird migratory flights from 30 July to 19 August 2005 and we encountered extensive birdmigration in the whole Beringia range from latitude 64 degrees N in Bering Strait up to latitude 75 degrees N far north of Wrangel Island, with eastward flights making up 79% of all track directions. The results from Beringia were used in combination with radar studies from the Arctic Ocean north of Siberia and in the Beaufort Sea to make a reconstruction of a major Siberian-American birdmigration system in a wide Arctic sector between longitudes 1108 E and 130 degrees W, spanning one-third of the entire circumpolar circle. This system was estimated to involve more than 2 million birds, mainly shorebirds, terns and skuas, flying across the Arctic Ocean at mean altitudes exceeding 1 km (maximum altitudes 3-5 km). Great circle orientation provided a significantly better fit with observed flight directions at 20 different sites and areas than constant geographical compass orientation. The long flights over the sea spanned 40-80 degrees of longitude, corresponding to distances and durations of 1400-2600 km and 26-48 hours, respectively. The birds continued from this eastward migration system over the Arctic Ocean into several different flyway systems at the American continents and the Pacific Ocean. Minimization of distances between tundra breeding sectors and northerly stopover sites, in combination with the Beringia glacial refugium and colonization history, seemed to be important for the evolution of this major polar bird migration system.

  • 5.
    Alerstam, Thomas
    et al.
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Bäckman, Johan
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Strandberg, Roine
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Gudmundsson, Gudmundur A.
    Iceland Inst Nat Hist, IS-125 Reykjavik, Iceland..
    Hedenström, Anders
    Lund Univ, Dept Theoret Ecol, SE-22362 Lund, Sweden..
    Henningsson, Sara S.
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Karlsson, Håkan
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Rosen, Mikael
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Great-circle migration of arctic passerines2008Ingår i: The AUK: A Quarterly Journal of Ornithology, ISSN 0004-8038, E-ISSN 1938-4254, Vol. 125, nr 4, s. 831-838Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Birds can save distance and time on their migratory journeys by following great circles rather than rhumblines, but great-circle routes require more complex orientation with changing courses. Flight directions at different places along the route and in relation to the destination can be used to test whether birds migrate along great circles or rhumblines. Such data have indicated great-circle migration among shorebirds at high latitudes, but no critical tests have been made for passerines. Using tracking radar on board the icebreaker Oden in August 2005, we recorded westerly flight directions of passerine migrants over the Chukchi Sea. The main sector of migratory directions was 237-311 degrees centered oil a mean heading direction of 274 degrees. The most likely species to participate in this westward trans-Beringia migration, mainly departing from Alaska, were Eastern Yellow Wagtail (Motacilla Ischutschensis), Arctic Warbler (Phylloscopus borealis kennicotti), Northern Wheatear (Oenanthe oenanthe), and Bluethroat (Luscinia svecica); all except the Bluethroat were recorded from the ship. Observed flight directions agreed with predicted great-circle courses but not with rhumbline courses for three of these four species with winter quarters in Southeast Asia; no definite conclusion could be drawn for the Northern Wheatear (wintering in East Africa). These results support great-circle migration among passerines traveling between Alaska and Old World winter quarters, though the long-distance precision and orientation mechanisms are Still unknown. The relative importance of different evolutionary causes-such as circumvention of geographic barriers, retracing of ancient colonization ways, or distance reduction by great-circle migration-to complex bird migration routes with changing courses remains to be understood. Received 24 August 2007, accepted 6 March 2008.

  • 6. Alerstam, Thomas
    et al.
    Rosén, Mikael
    Bäckman, Johan
    Ericson, Per G. P.
    Hellgren, Olof
    Flight speeds among bird species: allometric and phylogenetic effects2007Ingår i: PLoS biology, ISSN 1544-9173, E-ISSN 1545-7885Artikel i tidskrift (Refereegranskat)
  • 7. Alsos, I G
    et al.
    Engelskjon, T
    Gielly, L
    Taberlet, P
    Brochmann, C
    Impact of ice ages on circumpolar molecular diversity: insights from an ecological key species2005Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 14, nr 9, s. 2739-2753Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We address the impact of the ice age cycles on intraspecific cpDNA diversity, for the first time on the full circumboreal-circumarctic scale. The bird-dispersed bog bilberry (or arctic blueberry, Vaccinium uliginosum) is a key component of northern ecosystems and is here used to assess diversity in previously glaciated vs. unglaciated areas and the importance of Beringia as a refugium and source for interglacial expansion. Eighteen chloroplast DNA haplotypes were observed in and among 122 populations, grouping into three main lineages which probably diverged before, and thus were affected more or less independently by, all major glaciations. The boreal ‘Amphi-Atlantic lineage’ included one haplotype occurring throughout northern Europe and one occurring in eastern North America, suggesting expansion from at least two bottlenecked, glacial refugium populations. The boreal ‘Beringian lineage’ included seven haplotypes restricted to Beringia and the Pacific coast of USA. The ‘Arctic-Alpine lineage’ included nine haplotypes, one of them fully circumpolar. This lineage was unexpectedly diverse, also in previously glaciated areas, suggesting that it thrived on the vast tundras during the ice ages and recolonized deglaciated terrain over long distances. Its largest area of persistence during glaciations was probably situated in the north, stretching from Beringia and far into Eurasia, and it probably also survived the last glaciation in southern mountain ranges. Although Beringia apparently was important for the initial divergence and expansion of V. uliginosum as well as for continuous survival of both the Beringian and Arctic-Alpine lineages during all ice ages, this region played a minor role as a source for later interglacial expansions.

  • 8. Alsos, Inger Greve
    et al.
    Eidesen, Pernille Bronken
    Ehrich, Dorothee
    Skrede, Inger
    Westergaard, Kristine
    Jacobsen, Gro Hilde
    Landvik, Jon Y.
    Taberlet, Pierre
    Brochmann, Christian
    Frequent long-distance plant colonization in the changing Arctic2007Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 316, nr 5831, s. 1606-1609Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ability of species to track their ecological niche after climate change is a major source of uncertainty in predicting their future distribution. By analyzing DNA fingerprinting ( amplified fragment-length polymorphism) of nine plant species, we show that long-distance colonization of a remote arctic archipelago, Svalbard, has occurred repeatedly and from several source regions. Propagules are likely carried by wind and drifting sea ice. The genetic effect of restricted colonization was strongly correlated with the temperature requirements of the species, indicating that establishment limits distribution more than dispersal. Thus, it may be appropriate to assume unlimited dispersal when predicting long-term range shifts in the Arctic.

  • 9. Amon, Rainer M. W.
    A river runs through it: dissolved organic matter in the Arctic Ocean2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , s. 85 - 86Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 10. Ampomah, Osei Yaw
    et al.
    Huss-Danell, Kerstin
    Nodulation of Thermopsis lupinoides by a Mesorhizobium huakuii strain with a unique nodA gene in Kamtchatka, Russia2011Ingår i: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, s. 5513-5516Artikel i tidskrift (Refereegranskat)
  • 11. Ampomah, Osei Yaw
    et al.
    Mousavi, Seyed Abdollah
    Lindström, Kristina
    Huss-Danell, Kerstin
    Diverse Mesorhizobium bacteria nodulate native Astragalus and Oxytropis in arctic and subarctic areas in Eurasia2017Ingår i: Systematic and Applied Microbiology, ISSN 0723-2020, E-ISSN 1618-0984, Vol. 40, nr 1, s. 51-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract Rhizobia nodulating native Astragalus and Oxytropis spp. in Northern Europe are not well-studied. In this study, we isolated bacteria from nodules of four Astragalus spp. and two Oxytropis spp. from the arctic and subarctic regions of Sweden and Russia. The phylogenetic analyses were performed by using sequences of three housekeeping genes (16S rRNA, rpoB and recA) and two accessory genes (nodC and nifH). The results of our multilocus sequence analysis (MLSA) of the three housekeeping genes tree showed that all the 13 isolates belonged to the genus Mesorhizobium and were positioned in six clades. Our concatenated housekeeping gene tree also suggested that the isolates nodulating Astragalus inopinatus, Astragalus frigidus, Astragalus alpinus ssp. alpinus and Oxytropis revoluta might be designated as four new Mesorhizobium species. The 13 isolates were grouped in three clades in the nodC and nifH trees. 15N analysis suggested that the legumes in association with these isolates were actively fixing nitrogen.

  • 12. Amundsen, Helene
    et al.
    Anderson, Leif
    Andersson, Andreas
    Azetsu-Scott, Kumiko
    Bellerby, Richard
    Beman, Michael
    Browman, Howard I
    Carlson, Craig
    Cheung, William WL
    Chierici, Melissa
    AMAP Assessment 2013: Arctic Ocean Acidification2013Bok (Övrigt vetenskapligt)
  • 13. Anderson, L. G.
    et al.
    Tanhua, T.
    Bjork, G.
    Hjalmarsson, S.
    Jones, E. P.
    Jutterstrom, S.
    Rudels, B.
    Swift, J. H.
    Wahlstom, I.
    Arctic ocean shelf-basin interaction: An active continental shelf CO2 pump and its impact on the degree of calcium carbonate solubility2010Ingår i: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, E-ISSN 1879-0119, Vol. 57, nr 7, s. 869-879Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Arctic Ocean has wide shelf areas with extensive biological activity including a high primary productivity and an active microbial loop within the surface sediment. This in combination with brine production during sea ice formation result in the decay products exiting from the shelf into the deep basin typically at a depth of about 150 m and over a wide salinity range centered around S similar to 33. We present data from the Beringia cruise in 2005 along a section in the Canada Basin from the continental margin north of Alaska towards the north and from the International Siberian Shelf Study in 2008 (ISSS-08) to illustrate the impact of these processes. The water rich in decay products, nutrients and dissolved inorganic carbon (DIC), exits the shelf not only from the Chukchi Sea, as has been shown earlier, but also from the East Siberian Sea. The excess of DIC found in the Canada Basin in a depth range of about 50-250 m amounts to 90 +/- 40 g C m(-2). If this excess is integrated over the whole Canadian Basin the excess equals 320 +/- 140 x 10(12) g C. The high DIC concentration layer also has low pH and consequently a low degree of calcium carbonate saturation, with minimum aragonite values of 60% saturation and calcite values just below saturation. The mean age of the waters in the top 300 m was calculated using the transit time distribution method. By applying a future exponential increase of atmospheric CO2 the invasion of anthropogenic carbon into these waters will result in an under-saturated surface water with respect to aragonite by the year 2050, even without any freshening caused by melting sea ice or increased river discharge. (C) 2010 Elsevier Ltd. All rights reserved.

  • 14. Anderson, Leif G.
    Oceanographic investigations during leg 3 of the Beringia 2005 expedition2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , s. 87 - 91Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 15. Anderson, Leif G.
    et al.
    Andersson, Per S.
    Bjork, Goran
    Jones, E. Peter
    Jutterstrom, Sara
    Wahlstrom, Irene
    Source and formation of the upper halocline of the Arctic Ocean2013Ingår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 118, nr 1, s. 410-421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The upper halocline of the Arctic Ocean has a distinct chemical signature with high nutrient concentrations as well as low oxygen and pH values. This signature is formed in the Chukchi and East Siberian seas, by a combination of mineralization of organic matter and release of decay products to the sea ice brine enriched bottom water. Salinity and total alkalinity data show that the fraction of sea ice brine in the nutrient-enriched upper halocline water in the central Arctic Ocean is up to 4%. In the East Siberian Sea the bottom waters with exceptional high nutrient concentration and low pH have typically between 5 and 10% of sea ice brine as computed from salinity and oxygen-18 values. On the continental slope, over bottom depths of 150-200 m, the brine contribution was 6% at the nutrient maximum depth (50-100 m). At the same location as well as over the deeper basin the silicate maximum was found over a wider salinity range than traditionally found in the Canada Basin, in agreement with earlier observations east of the Chukchi Plateau. A detailed evaluation of the chemical and the temperature-salinity properties suggests at least two different areas for the formation of the nutrient-rich halocline within the East Siberian Sea. This has not been observed before 2004 and it could be a sign of a changing marine climate in the East Siberian Sea, caused by more open water in the summer season followed by more sea ice formation and brine production in the fall/winter. Citation: Anderson, L. G., P. S. Andersson, G. Bjork, E. Peter Jones, S. Jutterstrom, and I. Wahlstrom (2013), Source and formation of the upper halocline of the Arctic Ocean, J. Geophys. Res. Oceans, 118, 410-421, doi:10.1029/2012JC008291.

  • 16. Andersson, M. E.
    et al.
    Sommar, J.
    Gardfeldt, K.
    Lindqvist, O.
    Enhanced concentrations of dissolved gaseous mercury in the surface waters of the Arctic Ocean2008Ingår i: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 110, nr 3-4, s. 190-194Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During an almost three months long expedition in the Arctic Ocean, the Beringia 2005, dissolved gaseous mercury (DGM) was measured continuously in the surface water. The DGM concentration was measured using an equilibrium system, i.e. the DGM in the water phase equilibrated with a stream of gas and the gas was thereafter analysed with respect to its mercury content. The DGM concentrations were calculated using the following equation, DGM = Hg-eq / k(H’) where Hg-eq is the equilibrated concentration of elemental mercury in the gas phase and k(H’) is the dimensionless Henry’s law constant at desired temperature and salinity. During the expedition several features were observed. For example, enhanced DGM concentration was measured underneath the ice which may indicate that the sea ice acted as a barrier for evasion of mercury from the Arctic Ocean to the atmosphere. Furthermore, elevated DGM concentrations were observed in water that might have originated from river discharge. The gas-exchange of mercury between the ocean and the atmosphere was calculated in the open water and both deposition and evasion were observed. The measurements showed significantly enhanced DGM concentrations, compared to more southern latitudes. (C) 2008 Elsevier B.V. All rights reserved.

  • 17. Andersson, Maria
    Transport of mercury species in the environment2008Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 18. Andersson, Maria E.
    et al.
    Gardfeldt, Katarina
    Wangberg, Ingvar
    A description of an automatic continuous equilibrium system for the measurement of dissolved gaseous mercury2008Ingår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 391, nr 6, s. 2277-2282Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel continuous equilibrium system with high time resolution, i.e. every ten minutes, was developed to sample and determine dissolved gaseous mercury (DGM) in natural surface waters. The system is based on the opposite flow principle, can be connected to a ship’s bow water system, and can be applied under most ambient conditions, such as high wind speeds and onboard a moving ship. For the DGM determination the system uses the measured equilibrium concentration of mercury established between the aqueous and gaseous phases, i.e. DGM = Hg(extr) / k (H’), where Hg(extr) is the measured mercury concentration in the outgoing gas phase and k(H’) is the dimensionless Henry’s Law constant at the desired temperature and salinity. The efficiency of the system was investigated via theoretical calculations and by comparing the continuous equilibrium system with discrete samples. The measurements obtained by the continuous equilibrium system agree within 13% at the 95% confidence level with the measurements of discrete samples obtained by the traditional technique. The theoretical calculations estimated that the continuous equilibrium system described here had an efficiency of 99% for determining the DGM concentration.

  • 19. Andersson, Maria E.
    et al.
    Sommar, Jonas
    Gardfeldt, Katarina
    Jutterstrom, Sara
    Air-sea exchange of volatile mercury in the North Atlantic Ocean2011Ingår i: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 125, nr 1-4, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Part of the Beringia 2005 expedition covered the North Atlantic Ocean. During this passage, dissolved gaseous mercury (DGHg) in seawater and atmospheric concentrations of total gaseous mercury (TGHg), carbon monoxide (CO), and ozone (O-3) were measured continuously at high resolution. In addition, meteorological parameters such as wind speed and water temperature were measured continuously by the ship’s meteorological instrumentation. The DGHg concentration was measured using a continuous equilibrium system where the elemental mercury in the sea water was equilibrated with a stream of gas. The DGHg concentration was calculated using DGHg=Hg-eq/k(H), where Hg-eq is the concentration of elemental mercury in the equilibrated air and k(H), is the dimensionless Henry’s law constant. The degree of saturation was determined directly from the measurements S = Hg-eq/TGHg. The water sampled had an average DGHg concentration of 58 +/- 10 fM and the average TGHg concentration was determined to 1.7 +/- 0.1 ng m(-3). The water sampled was under- and super-saturated with respect to elemental mercury covering a large range of saturation of 70 to 230% resulting in an average degree of saturation of 150 +/- 30%. Therefore, both evasion and deposition of elemental mercury were observed in the sampled water. In the light of the average flux, 2.1 +/- 1.8 pmol m(-2) h(-1), it is concluded that mostly evasion occured during the sampling period. (C) 2011 Elsevier B.V. All rights reserved.

  • 20. Andersson, Maria
    et al.
    Sommar, Jonas
    Gårdfeldt, Katarina
    Air-sea flux of volatile mercury over the North Atlantic Ocean2008Ingår i: Transport of mercury species in the environment. Exchange between oceanic waters and the atmosphere, Göteborg: Göteborg Univ., Dept. of Chemistry , 2008, , s. Paper IVKapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 21. Andersson, Maria
    et al.
    Sommar, Jonas
    Gårdfeldt, Katarina
    Lindqvist, O.
    Accumulation of mercury in the Arctic Ocean2008Ingår i: Marine Chemistry, Vol. 110, s. 190-194Artikel i tidskrift (Refereegranskat)
  • 22. Andersson, Per
    Biochemistry, trace elements and isotopes in Arctic Ocean margins2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , s. 92 - 94Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 23. Angerbjörn, Anders
    Evolutionary consequences of the Pleistocene glacial cycles2006Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretaria , 2006, s. 156-158Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 24. Bakker, D. C. E.
    et al.
    Pfeil, B.
    Landa, C. S.
    Metzl, N.
    O’Brien, K. M.
    Olsen, A.
    Smith, K.
    Cosca, C.
    Harasawa, S.
    Jones, S. D.
    Nakaoka, S. -I
    Nojiri, Y.
    Schuster, U.
    Steinhoff, T.
    Sweeney, C.
    Takahashi, T.
    Tilbrook, B.
    Wada, C.
    Wanninkhof, R.
    Alin, S. R.
    Balestrini, C. F.
    Barbero, L.
    Bates, N. R.
    Bianchi, A. A.
    Bonou, F.
    Boutin, J.
    Bozec, Y.
    Burger, E. F.
    Cai, W. -J
    Castle, R. D.
    Chen, L.
    Chierici, M.
    Currie, K.
    Evans, W.
    Featherstone, C.
    Feely, R. A.
    Fransson, A.
    Goyet, C.
    Greenwood, N.
    Gregor, L.
    Hankin, S.
    Hardman-Mountford, N. J.
    Harlay, J.
    Hauck, J.
    Hoppema, M.
    Humphreys, M. P.
    Hunt, C. W.
    Huss, B.
    Ibánhez, J. S. P.
    Johannessen, T.
    Keeling, R.
    Kitidis, V.
    Körtzinger, A.
    Kozyr, A.
    Krasakopoulou, E.
    Kuwata, A.
    Landschützer, P.
    Lauvset, S. K.
    Lefèvre, N.
    Lo Monaco, C.
    Manke, A.
    Mathis, J. T.
    Merlivat, L.
    Millero, F. J.
    Monteiro, P. M. S.
    Munro, D. R.
    Murata, A.
    Newberger, T.
    Omar, A. M.
    Ono, T.
    Paterson, K.
    Pearce, D.
    Pierrot, D.
    Robbins, L. L.
    Saito, S.
    Salisbury, J.
    Schlitzer, R.
    Schneider, B.
    Schweitzer, R.
    Sieger, R.
    Skjelvan, I.
    Sullivan, K. F.
    Sutherland, S. C.
    Sutton, A. J.
    Tadokoro, K.
    Telszewski, M.
    Tuma, M.
    van Heuven, S. M. A. C.
    Vandemark, D.
    Ward, B.
    Watson, A. J.
    Xu, S.
    A multi-decade record of high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)2016Ingår i: Earth System Science Data, Vol. 8, nr 2, s. 383-413Artikel i tidskrift (Refereegranskat)
  • 25. Baskaran, M
    Interaction of sea ice sediments and surface sea water in the Arctic Ocean: Evidence from excess Pb-2102005Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, nr 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We measured the activities of Pb-210, Ra-226, U-238 and Cs-137 in a suite of ice-rafted sediments (IRS) from the Arctic Ocean in an attempt to assess the interaction of sea ice sediments and surface water. The concentrations of these nuclides were compared to those of the benthic sediments in the coastal and shelf regions of the Arctic Ocean, which are believed to be the major source region for the IRS. The concentration factors (CF = activity of a nuclide in IRS/average activity in benthic sediments) are similar to 1 and 4-92 for Cs-137 and Pb-210, respectively. The CF values for Cs-137 are comparable to the values that can be obtained from the previously published data while we report the first set of high CF values of Pb-210. A major portion of Pb-210 in some IRS samples is likely derived from surface waters and thus, the concentrations of Pb-210 combined with another particle-reactive radionuclide (such as Be-7, Th-234) in IRS might provide information on the residence time and transit time of sea ice-laden sediments.

  • 26. Bennett, Keith
    Late Quaternary environmental change of Kamchatka2005Ingår i: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2005, , s. 157 - 158Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 27.
    Benskin, Jonathan P.
    et al.
    Univ Alberta, Dept Lab Med & Pathol, Edmonton, AB, Canada..
    Ahrens, Lutz
    Helmholtz Zentrum Geesthacht, Inst Coastal Res, Geesthacht, Germany..
    Muir, Derek C. G.
    Environm Canada, Aquat Ecosyst Protect Res Div, Water Sci & Technol Directorate, Burlington, ON L7R 4A6, Canada..
    Scott, Brian F.
    Environm Canada, Aquat Ecosyst Protect Res Div, Water Sci & Technol Directorate, Burlington, ON L7R 4A6, Canada..
    Spencer, Christine
    Environm Canada, Aquat Ecosyst Protect Res Div, Water Sci & Technol Directorate, Burlington, ON L7R 4A6, Canada..
    Rosenberg, Bruno
    Fisheries & Oceans Canada, Arctic Aquat Res Div, Winnipeg, MB, Canada..
    Tomy, Gregg
    Fisheries & Oceans Canada, Arctic Aquat Res Div, Winnipeg, MB, Canada..
    Kylin, Henrik
    Linkoping Univ, Dept Water & Environm Studies, S-58183 Linkoping, Sweden..
    Lohmann, Rainer
    Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA..
    Martin, Jonathan W.
    Univ Alberta, Dept Lab Med & Pathol, Edmonton, AB, Canada..
    Manufacturing Origin of Perfluorooctanoate (PFOA) in Atlantic and Canadian Arctic Seawater2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 2, s. 677-685Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA, in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to similar to 50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.,

  • 28.
    Benskin, Jonathan P.
    et al.
    Univ Alberta, Dept Lab Med & Pathol, Edmonton, AB T6G 2G3, Canada..
    Muir, Derek C. G.
    Environm Canada, Aquat Contaminants Res Div, Burlington, ON L7R 4A6, Canada..
    Scott, Brian F.
    Environm Canada, Aquat Contaminants Res Div, Burlington, ON L7R 4A6, Canada..
    Spencer, Christine
    Environm Canada, Aquat Contaminants Res Div, Burlington, ON L7R 4A6, Canada..
    De Silva, Amila O.
    Environm Canada, Aquat Contaminants Res Div, Burlington, ON L7R 4A6, Canada..
    Kylin, Henrik
    Linkoping Univ, Dept Water & Environm Studies, SE-58183 Linkoping, Sweden..
    Martin, Jonathan W.
    Univ Alberta, Dept Lab Med & Pathol, Edmonton, AB T6G 2G3, Canada..
    Morris, Adam
    Univ Guelph, Dept Environm Biol, Guelph, ON N1G 2W1, Canada..
    Lohmann, Rainer
    Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA..
    Tomy, Gregg
    Dept Fisheries & Oceans Canada, Arctic Aquat Res Div, Winnipeg, MB R3T 2N6, Canada..
    Rosenberg, Bruno
    Dept Fisheries & Oceans Canada, Arctic Aquat Res Div, Winnipeg, MB R3T 2N6, Canada..
    Taniyasu, Sachi
    Natl Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki 3058569, Japan..
    Yamashita, Nobuyoshi
    Natl Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki 3058569, Japan..
    Perfluoroalkyl Acids in the Atlantic and Canadian Arctic Oceans2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 11, s. 5815-5823Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report here on the spatial distribution of C-4, C-6, and C-8 perfluoroalkyl sulfonates, C-6-C-14 perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (Sigma PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). Sigma PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L Sigma PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, Sigma PFAAs were <210 pg/L. PFOA/PFOS ratios were typically >= 1 in the northern hemisphere, similar to 1 near the equator, and <= 1 in the southern hemisphere. In the Canadian Arctic, Sigma PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically >>1) decreased from Baffin Bay to the Amundsen Gulf; possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.

  • 29. Bjork, Goran
    et al.
    Jakobsson, Martin
    Rudes, Bert
    Swift, James H.
    Anderson, Leif
    Darby, Dennis A.
    Backman, Jan
    Coakley, Bernard
    Winsor, Peter
    Polyak, Leonid
    Edwards, Margo
    Bathymetry and deep-water exchange across the central Lomonosov Ridge at 88-89 degrees N2007Ingår i: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, E-ISSN 1879-0119, Vol. 54, nr 8, s. 1197-1208Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seafloor mapping of the central Lomonosov Ridge using a multibeam echo-sounder during the Beringia/Healy-Oden Trans-Arctic Expedition (HOTRAX) 2005 shows that a channel across the ridge has a substantially shallower sill depth than the similar to 2500 m indicated in present bathymetric maps. The multibeam survey along the ridge crest shows a maximum sill depth of about 1870 m. A previously hypothesized exchange of deep water from the Amundsen Basin to the Makarov Basin in this area is not confirmed. On the contrary, evidence of a deep-water flow from the Makarov to the Amundsen Basin was observed, indicating the existence of a new pathway for Canadian Basin Deep Water toward the Atlantic Ocean. Sediment data show extensive current activity along the ridge crest and along the rim of a local Intra Basin within the ridge structure.(c) 2007 Elsevier Ltd. All rights reserved.

  • 30. Bonnedahl, Jonas
    Antibiotic Resistance in Enterobacteriaceae Isolated from Wild Birds2011Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The presence and spread of clinically important antibiotic-resistant bacteria in reservoirs from natural environments are not well studied compared to the clinical environments. The overall aim of this project was to study the presence of clinically important antibiotic-resistant bacteria in a reservoir from natural environments. Wild birds were chosen not only as indicators of the level of antibiotic resistance in surrounding natural bacterial populations, but also since birds can act as vectors of several potential pathogens including enteropathogens and because they by migration have an ability to spread these pathogens across geographical regions. The studies in this thesis showed that wild birds carry antibiotic-resistant enterobacteriaceae. The levels and spectrum of antibiotic resistance varies between different bird populations and geographical regions. In bird populations without interaction with human activities throughout the year, antibiotic resistance is lacking. Antibiotic-resistant bacteria could however probably be dispersed to remote regions by bird migration. Extended-spectrum beta-lactamases (ESBLs) and especially CTX-M types are found in comparable high levels in gull populations considering the recent emergence of these resistance genes in clinical settings. The CTX-M types found in wild birds are the same types that are found in clinical settings and in food producing animals from the same regions. ESBL-producing E. coli isolated from Yellow-legged Gulls are genetically heterogenous, reflecting that these resistance genes are present across the full E. coli genetic diversity. In wild birds CTX-M are found both in E. coli strains with previously known “human signature” as well as “novel” strains. This indicates that these genes are indeed very mobile and rapidly dispersing both through horizontal gene transfer and through successful clones. The findings in this thesis indicate that bird colonies could act as melting pots and reservoirs for new resistance types and that wild birds could act as important indicators of the level of antibiotic resistance dispersal in natural environments.

  • 31. Bronken Eidesen, Pernilla
    et al.
    Carlsen, Tor
    Molau, Ulf
    Brochmann, Christian
    Repeatedly out of Beringia: Cassiope tetragona embraces the Arctic2007Ingår i: Journal of Biogeography, Vol. 34, s. 1559-1574Artikel i tidskrift (Refereegranskat)
  • 32. Cai, Wei-Jun
    et al.
    Bates, Nicholas R.
    Guo, Laodong
    Anderson, Leif G.
    Mathis, Jeremy T.
    Wanninkhof, Rik
    Hansell, Dennis A.
    Chen, Liqi
    Semiletov, Igor P.
    Carbon Fluxes Across Boundaries in the Pacific Arctic Region in a Changing Environment2014Ingår i: The Pacific Arctic Region: Ecosystem Status and Trends in a Rapidly Changing Environment / [ed] Grebmeier, Jacqueline M.; Maslowski, Wieslaw, Springer Netherlands, 2014, s. 199-222Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 33. Carrizo, Daniel
    et al.
    Gustafsson, Orjan
    Distribution and Inventories of Polychlorinated Biphenyls in the Polar Mixed Layer of Seven Pan-Arctic Shelf Seas and the Interior Basins2011Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 45, nr 4, s. 1420-1427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Assessment of the Arctic as a global repository of polychlorinated biphenyls (PCBs) and of uptake processes in the base of its marine food chain hinges on reliable information of PCB distribution in surface seawater, yet there is a scarcity of quality-assured PCB measurements in this key compartment. Here, surface seawater PCB concentrations and congener fingerprints are evaluated for all seven pan-Arctic shelf seas and for the interior basins. Particulate and dissolved PCBs were collected via trace-clean protocols on three basin-wide expeditions (AO-01, Beringia-2005, and ISSS-08). Concentrations of the sum of 13 abundant congeners (Sigma(13)PCB) were 0.13-21 pg/L, with higher concentrations in the shelf seas and lower concentrations in the Central Arctic Basin. Trichlorinated PCBs constituted about half of the total loadings in the Eastern Arctic (Beaufort, Chukchi, East Siberian, and Laptev Seas) and in the Central Basin, indicating an atmospheric source. In contrast, hexachlorinated PCBs were more abundant than tri-PCBs in the western sector, suggesting a role also for waterborne transport from regions of heavy PCB consumption in North America and Europe. Finally, the inventory of Sigma(13)PCB in the polar mixed layer of the entire Arctic Ocean was 0.39 ton, which implies that only 0.0008% of historical PCB emissions are now residing in Arctic surface waters.

  • 34. Chierici, M.
    et al.
    Fransson, A.
    Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves2009Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 6, nr 11, s. 2421-2431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the summer of 2005, we sampled surface water and measured pH and total alkalinity (A(T)) underway aboard IB Oden along the Northwest Passage from Cape Farewell (South Greenland) to the Chukchi Sea. We investigated the variability of carbonate system parameters, focusing particularly on carbonate concentration [CO32-] and calcium carbonate saturation states, as related to freshwater addition, biological processes and physical upwelling. Measurements on A(T), pH at 15 degrees C, salinity (S) and sea surface temperature (SST), were used to calculate total dissolved inorganic carbon (C-T), [CO32-] and the saturation of aragonite (Omega Ar) and calcite (Omega Ca) in the surface water. The same parameters were measured in the water column of the Bering Strait. Some surface waters in the Canadian Arctic Archipelago (CAA) and on the Mackenzie shelf (MS) were found to be undersaturated with respect to aragonite (Omega Ar<1). In these areas, surface water was low in AT and CT (<1500 mu mol kg(-1)) relative to seawater and showed low [CO32-]. The low saturation states were probably due to the likely the effect of dilution due to freshwater addition by sea ice melt (CAA) and river runoff (MS). High A(T) and C-T and low pH, corresponded with the lowest [CO32-], Omega Ar and Omega Ca, observed near Cape Bathurst and along the South Chukchi Peninsula. This was linked to the physical upwelling of subsurface water with elevated CO2. The highest surface Omega Ar and Omega Ca of 3.0 and 4.5, respectively, were found on the Chukchi Sea shelf and in the cold water north of Wrangel Island, which is heavily influenced by high CO2 drawdown and lower C-T from intense biological production. In the western Bering Strait, the cold and saline Anadyr Current carries water that is enriched in A(T) and C-T from enhanced organic matter remineralization, resulting in the lowest Omega Ar (similar to 1.2) of the area.

  • 35. Christerson, Linus
    et al.
    Blomqvist, Maria
    Grannas, Karin
    Thollesson, Mikael
    Laroucau, Karine
    Waldenstrom, Jonas
    Eliasson, Ingvar
    Olsen, Bjorn
    Herrmann, Bjorn
    A novel Chlamydiaceae-like bacterium found in faecal specimens from sea birds from the Bering Sea2010Ingår i: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 2, nr 4, s. 605-610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    P>The family Chlamydiaceae contains several bacterial pathogens of important human and veterinary medical concern, such as Chlamydia trachomatis and Chlamydophila psittaci. Within the order Chlamydiales there are also an increasing number of chlamydia-like bacteria whose biodiversity, host range and environmental spread seem to have been largely underestimated, and which are currently being investigated for their potential medical relevance. In this study we present 16S rRNA, rnpB and ompA gene sequence data congruently indicating a novel chlamydia-like bacterium found in faecal specimens from opportunistic fish-eating sea birds, belonging to the Laridae and Alcidae families, from the Bering Sea. This novel bacterium appears to be closer to the Chlamydiaceae than other chlamydia-like bacteria and is most likely a novel genus within the Chlamydiaceae family.

  • 36. Colleoni, F.
    et al.
    Krinner, G.
    Jakobsson, M.
    Sensivity of the Late Saalian (140 kyrs BP) and LGM (21 kyrs BP) Eurasian ice sheet surface mass balance to vegetation feedbacks2009Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, nr L08704, s. 5-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work uses an atmospheric general circulation model (AGCM) asynchronously coupled to an equilibrium vegetation model to investigate whether vegetation feedbacks could be one of the reasons why the Late Saalian ice sheet (140 kyrs BP) in Eurasia was substantially larger than the Last Glacial Maximum (LGM, 21 kyrs BP) Eurasian ice sheet. The modeled vegetation changes induce a regional cooling for the Late Saalian while they cause a slight regional warming for LGM. As a result, ablation along the margins of the Late Saalian ice sheet is significantly reduced, leading to an increased surface mass balance, while there are no significant mass balance changes observed from vegetation feedbacks at LGM.

  • 37. Comstedt, Par
    et al.
    Asokliene, Loreta
    Eliasson, Ingvar
    Olsen, Bjorn
    Wallensten, Anders
    Bunikis, Jonas
    Bergstrom, Sven
    Complex Population Structure of Lyme Borreliosis Group Spirochete Borrelia garinii in Subarctic Eurasia2009Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 4, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Borrelia garinii, a causative agent of Lyme borreliosis in Europe and Asia, is naturally maintained in marine and terrestrial enzootic cycles, which primarily involve birds, including seabirds and migratory passerines. These bird groups associate with, correspondingly, Ixodes uriae and Ixodes ricinus ticks, of which the latter species may bite and transmit the infection to humans. Studies of the overlap between these two natural cycles of B. garinii have been limited, in part due to the absence of representative collections of this spirochete’s samples, as well as of the lack of reliable measure of the genetic heterogeneity of its strains. As a prerequisite for understanding the epidemiological correlates of the complex maintenance of B. garinii, the present study sought to assess the diversity and phylogenetic relationships of this species’ strains from its natural hosts and patients with Lyme borreliosis from subarctic Eurasia. We used sequence typing of the partial rrs-rrl intergenic spacer (IGS) of archived and prospective samples of B. garinii from I. uriae ticks collected predominantly on Commander Islands in North Pacific, as well as on the islands in northern Sweden and arctic Norway. We also typed B. garinii samples from patients with Lyme borreliosis and I. ricinus ticks infesting migratory birds in southern Sweden, or found questing in selected sites on the islands in the Baltic Sea and Lithuania. Fifty-two (68%) of 77 B. garinii samples representing wide geographical range and associated with I. ricinus and infection of humans contributed 12 (60%) of total 20 identified IGS variants. In contrast, the remaining 25 (32%) samples recovered from I. uriae ticks from a few islands accounted for as many as 10 (50%) IGS types, suggesting greater local diversity of B. garinii maintained by seabirds and their ticks. Two IGS variants of the spirochete in common for both tick species were found in I. ricinus larvae from migratory birds, an indication that B. garinii strains are exchanged between different ecological niches. Notably, B. garinii variants associated with I. uriae ticks were found in each of the six clusters, representing two phylogenetic lineages of this species identified among the studied samples. Our findings suggest that B. garinii in subarctic Eurasia comprises two partially overlapping populations with different levels of genetic heterogeneity, presumably, due to distinctive selective pressures on the spirochete in its marine and terrestrial enzootic cycles.

  • 38. Cronin, T. M.
    et al.
    Dwyer, G. S.
    Farmer, J.
    Bauch, H. A.
    Spielhagen, R. F.
    Jakobsson, M.
    Nilsson, J.
    Briggs, Jr., W. M.
    Stepanova, A.
    Deep Arctic Ocean warming during the last glacial cycle2012Ingår i: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 5, nr 9, s. 631-634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the Arctic Ocean, the cold and relatively fresh water beneath the sea ice is separated from the underlying warmer and saltier Atlantic Layer by a halocline. Ongoing sea ice loss and warming in the Arctic Ocean(1-7) have demonstrated the instability of the halocline, with implications for further sea ice loss. The stability of the halocline through past climate variations(8-10) is unclear. Here we estimate intermediate water temperatures over the past 50,000 years from the Mg/Ca and Sr/Ca values of ostracods from 31 Arctic sediment cores. From about 50 to 11 kyr ago, the central Arctic Basin from 1,000 to 2,500 m was occupied by a water mass we call Glacial Arctic Intermediate Water. This water mass was 1-2 degrees C warmer than modern Arctic Intermediate Water, with temperatures peaking during or just before millennial-scale Heinrich cold events and the Younger Dryas cold interval. We use numerical modelling to show that the intermediate depth warming could result from the expected decrease in the flux of fresh water to the Arctic Ocean during glacial conditions, which would cause the halocline to deepen and push the warm Atlantic Layer into intermediate depths. Although not modelled, the reduced formation of cold, deep waters due to the exposure of the Arctic continental shelf could also contribute to the intermediate depth warming.

  • 39.
    Cronin, T. M.
    et al.
    US Geol Survey, MS 926A, Reston, VA 20192 USA..
    Gemery, L.
    US Geol Survey, MS 926A, Reston, VA 20192 USA..
    Briggs, W. M., Jr.
    Univ Colorado, Inst Arctic & Alpine Res INSTAAR, Boulder, CO 80309 USA..
    Jakobsson, M.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Polyak, L.
    Ohio State Univ, Byrd Polar Res Ctr, Columbus, OH 43210 USA..
    Brouwers, E. M.
    US Geol Survey, MS 406, Denver Fed Ctr, Denver, CO 80225 USA..
    Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy2010Ingår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, nr 25-26, s. 3415-3429Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. Published by Elsevier Ltd.

  • 40. Danell, Kjell
    Plant - herbivore systems in Kamchatka2000Ingår i: Polarforskningssekretariatets årsbok 1999, Stockholm: Swedish Polar Research Secretariat , 2000, , s. 121 - 124Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 41. Darby, D.
    et al.
    Jakobsson, M.
    Polyak, L.
    Icebreaker Expedition Collects Key Arctic Seafloor and Ice Data2005Ingår i: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 86, nr 52, s. 549-556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recently completed Healy-Oden Trans-Arctic Expedition 2005 (HoTrAX'05) retrieved 29 piston cores averaging nearly 12 meters in length from a complete transect across the central Arctic ocean (Figure 1).These cores provide a critically-needed sample cache for both a pan-Arctic stratigraphy and a long-awaited paleoclimate record that it is hoped will greatly improve the understanding of how deepwater is exchanged between Arctic basins, how the climate system in the Arctic works over longer time intervals, and how the Arctic system interacts with global systems. The coring was done from the U.s. Coast Guard Cutter (UsCGC) Healy, while oceanographic measurements were made from the Swedish icebreaker Oden. In addition to coring and oceanography, HoTrAX mapped the seafloor with multibeam bathymetry and collected chirp sonar profiles that not only mapped the strata to a sub-bottom depth of 50–100 meters , but also provided detailed information on the geologic context of the core sites.

  • 42. Darby, D.A.
    et al.
    Ortiz, J.
    Polyak, L.
    Lund, S.
    Jakobsson, M.
    Woodgate, R.A.
    The role of currents and sea ice in both slowly deposited central Arctic and rapidly deposited Chukchi–Alaskan margin sediments2009Ingår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 68, nr 1-2, s. 58-72Artikel i tidskrift (Refereegranskat)
  • 43. Darby, Dennis A.
    et al.
    Jakobsson, Martin
    Rigor, Ignatius
    NEW INSIGHTS IN SEA ICE DRIFT BASED ON DIRTY ICE SAMPLES COLLECTED IN 2005 BY THE HOTRAX EXPEDITION2006Ingår i: AGU Fall Meeting, 11–15 December 2006, Moscone West, 800 Howard StreetMoscone South, Howard Street (between 3rd and 4th streets)San Francisco, CA, USA, 2006, , s. 1Konferensbidrag (Övrigt vetenskapligt)
  • 44.
    Darby, Dennis A.
    et al.
    Old Dominion Univ, Dept Ocean Earth & Atmospher Sci, Norfolk, VA 23529 USA..
    Myers, Wesley B.
    Old Dominion Univ, Dept Ocean Earth & Atmospher Sci, Norfolk, VA 23529 USA..
    Jakobsson, Martin
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden..
    Rigor, Ignatius
    Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA..
    Modern dirty sea ice characteristics and sources: The role of anchor ice2011Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, ISSN 2169-9275, Vol. 116, artikel-id C09008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Extensive dirty ice patches with up to 7 kg m(-2) sediment concentrations in layers of up to 10 cm thickness were encountered in 2005 and 2007 in numerous areas across the central Arctic. The Fe grain fingerprint determination of sources for these sampled dirty ice floes indicated both Russian and Canadian sources, with the latter dominating. The presence of benthic shells and sea weeds along with thick layers (2-10 cm) of sediment covering 5-10 m(2) indicates an anchor ice entrainment origin as opposed to suspension freezing for some of these floes. The anchor ice origin might explain the dominance of Canadian sources where only narrow flaw leads occur that would not favor suspension freezing as an entrainment process. Expandable clays, commonly used as an indicator of a Kara Sea origin for dirty sea ice, are present in moderately high percentages (>20%) in many circum-Arctic source areas, including the Arctic coasts of North America. Some differences between the Russian and the North American coastal areas are found in clay mineral abundance, primarily the much higher abundance of chlorite in North America and the northern Barents Sea as opposed to the rest of the Russian Arctic. However, sea ice clay mineralogy matched many source areas, making it difficult to use as a provenance tool by itself. The bulk mineralogy (clay and non-clay) does not match specific sources possibly due to reworking of the sediment in dirty floes through summer melting or the failure to characterize all possible source areas.

  • 45. Darby, Dennis A.
    et al.
    Polyak, Leonid
    Jakobsson, Martin
    The 2005 HOTRAX Expedition to the Arctic Ocean2009Ingår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 68, nr 1-2, s. 4-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Healy–Oden Trans-Arctic Expedition (HOTRAX'05) recovered 29 long piston cores and associated multicores along a transect from the Alaskan margin across the central Arctic Ocean to the northern Svalbard margin. The initial results focus on the age and stratigraphy of these cores using a variety of approaches including radiocarbon, paleomagnetic and other chronostratigraphic methods as well as detailed correlations of proxy records. High sedimentation cores from probable drift deposits are described from the shelf and continental slope north of Alaska. Provenance and sedimentary processes in these deposits include both currents and sea-ice rafting. Much lower sedimentation rates in the central Arctic Ocean show geographic variability consistent with the patterns of expected sediment distribution by ice and, to a smaller extent, subsurface currents. Insights into the Upper Quaternary stratigraphy and depositional history are provided in two papers on a core from the Mendeleev Ridge with sedimentation rates relatively elevated for this region. To compliment the results from the HOTRAX cores, two papers are included dealing with the stratigraphy and sedimentary processes on the Chukchi shelf and a modeling study addressing why the Marine Isotopic Stage 6 (ca. 140 ka) glaciation was substantially more extensive in the Arctic than the Last Glacial Maximum.

  • 46. Delling, B.
    et al.
    Palm, S.
    Palkopoulou, E.
    Prestegaard, T.
    Genetic signs of multiple colonization events in Baltic ciscoes with radiation into sympatric spring- and autumn-spawners confined to early postglacial arrival2014Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Presence of sympatric populations may reflect local diversification or secondary contact of already distinct forms. The Baltic cisco (Coregonus albula) normally spawns in late autumn, but in a few lakes in Northern Europe sympatric autumn and spring- or winter-spawners have been described. So far, the evolutionary relationships and taxonomic status of these main life history forms have remained largely unclear. With microsatellites and mtDNA sequences, we analyzed extant and extinct spring- and autumn-spawners from a total of 23 Swedish localities, including sympatric populations. Published sequences from Baltic ciscoes in Germany and Finland, and Coregonus sardinella from North America were also included together with novel mtDNA sequences from Siberian C.sardinella. A clear genetic structure within Sweden was found that included two population assemblages markedly differentiated at microsatellites and apparently fixed for mtDNA haplotypes from two distinct clades. All sympatric Swedish populations belonged to the same assemblage, suggesting parallel evolution of spring-spawning rather than secondary contact. The pattern observed further suggests that postglacial immigration to Northern Europe occurred from at least two different refugia. Previous results showing that mtDNA in Baltic cisco is paraphyletic with respect to North American C.sardinella were confirmed. However, the inclusion of Siberian C.sardinella revealed a more complicated pattern, as these novel haplotypes were found within one of the two main C.albula clades and were clearly distinct from those in North American C.sardinella. The evolutionary history of Northern Hemisphere ciscoes thus seems to be more complex than previously recognized.

  • 47.
    Dowdeswell, J. A.
    et al.
    Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England..
    Jakobsson, M.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Hogan, K. A.
    Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England..
    O'Regan, M.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Backman, J.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Evans, J.
    Univ Loughborough, Dept Geog, Loughborough LE11 3TU, Leics, England..
    Hell, B.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Löwemark, L.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Marcussen, C.
    Geol Survey Denmark & Greenland, DK-1350 Copenhagen, Denmark..
    Noormets, R.
    Univ Ctr Svalbard, N-9171 Longyearbyen, Norway..
    Cofaigh, C. O.
    Univ Durham, Dept Geog, Durham DH1 3LE, England..
    Sellen, E.
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Sölvsten, M.
    Royal Danish Adm Nav & Hydrog, DK-1023 Copenhagen K, Denmark..
    High-resolution geophysical observations of the Yermak Plateau and northern Svalbard margin: implications for ice-sheet grounding and deep-keeled icebergs2010Ingår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, nr 25-26, s. 3518-3531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-resolution geophysical evidence on the seafloor morphology and acoustic stratigraphy of the Yermak Plateau and northern Svalbard margin between 79 degrees 20' and 81 degrees 30'N and 5 degrees and 22 degrees E is presented. Geophysical datasets are derived from swath bathymetry and sub-bottom acoustic profiling and are combined with existing cores to derive chronological control. Seafloor landforms, in the form of ice-produced lineations, iceberg ploughmarks of various dimensions (including features over 80 m deep and down to about 1000 m), and a moat indicating strong currents are found. The shallow stratigraphy of the Yermak Plateau shows three acoustic units: the first with well-developed stratification produced by hemipelagic sedimentation, often draped over a strong and undulating internal reflector; a second with an undulating upper surface and little acoustic penetration, indicative of the action of ice; a third unit of an acoustically transparent facies, resulting from debris flows. Core chronology suggests a MIS 6 age for the undulating seafloor above about 580 m. There are several possible explanations, including: (a) the flow of a major grounded ice sheet across the plateau crest from Svalbard (least likely given the consolidation state of the underlying sediments); (b) the more transient encroachment of relatively thin ice from Svalbard; or (c) the drift across the plateau of an ice-shelf remnant or megaberg from the Arctic Basin. The latter is our favoured explanation given the evidence currently at our disposal. (C) 2010 Elsevier Ltd. All rights reserved.

  • 48. Drobni, Mirva
    et al.
    Bonnedahl, Jonas
    Hernandez, Jorge
    Haemig, Paul D.
    Olsen, Björn
    Vancomycin-resistant Entercocci, Point Barrow, Alaska, USA2009Ingår i: Emerging Infectious Diseases, Vol. 15, nr 5, s. 838-839Artikel i tidskrift (Refereegranskat)
  • 49. Drobni, Mirva
    et al.
    Bonnedahl, Jonas
    Hernandez, Jorge
    Haemig, Paul
    Olsen, Bjorn
    Vancomycin-Resistant Enterococci, Point Barrow, Alaska, USA2009Ingår i: Emerging Infectious Diseases, ISSN 1080-6040, E-ISSN 1080-6059, Vol. 15, nr 5, s. 838-839Artikel i tidskrift (Refereegranskat)
  • 50. Ehrich, D.
    et al.
    Alsos, I. G.
    Brochmann, C.
    Where did the northern peatland species survive the dry glacials? Cloudberry (Rubus chamaemorus) as an example2008Ingår i: Journal of Biogeography, Vol. 35, s. 801-814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim During the last ice age large parts of the north boreal and subarctic zones were covered by ice, while the climate in ice-free regions of northern Asia was extremely cold and dry. The extensive peatlands of these zones with their characteristic vegetation developed at the beginning of the Holocene. We combine a phylogeographical approach with maps of pollen records to identify regions where Rubus chamaemorus, a plant of moist, peaty soils, was likely to grow during this period. Location Circumarctic/circumboreal. Methods Samples were collected from 45 locations throughout much of the range of R. chamaemorus and 398 plants were analysed with amplified fragment length polymorphism (AFLP). Estimates of diversity and differentiation, principal coordinates analysis and Bayesian clustering methods were used for the analysis of genetic data. Dated pollen records were retrieved from the European and the Global Pollen Databases. Results The plants from Sakhalin are highly divergent from the rest of the material and represent the previously described var. pseudochamaemorus. The main genetic division in R. chamaemorus sensu stricto is found in the Taymyr region in central Eurasia. Genetic diversity and the relative number of rare markers are highest in central Siberia and eastern Asia and decrease towards Europe and to a lesser extent eastwards through North America. Pollen dating back to the last ice age is found in central and eastern Siberia and Alaska. The maximum observed clone size is about 250 m, and more than one clone is found in nearly every local population. Main conclusions The genetic data are consistent with the pollen records and indicate that R. chamaemorus was growing in several areas of northern central Siberia and Beringia during the last glaciation. This finding suggests that sufficient humidity for this and other species of peaty soils was present locally in different parts of the generally dry ice-free areas of northern Asia, as had been previously documented for Beringia. The AFLP data show that var. pseudochamaemorus, which is also morphologically quite divergent, clearly represents a distinct genetic entity.

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