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Sample records for canadian arctic gas

  1. Science Traverses in the Canadian High Arctic

    NASA Technical Reports Server (NTRS)

    Williamson, Marie-Claude

    2012-01-01

    The presentation is divided into three parts. Part I is an overview of early expeditions to the High Arctic, and their political consequences at the time. The focus then shifts to the Geological Survey of Canada s mapping program in the North (Operation Franklin), and to the Polar Continental Shelf Project (PCSP), a unique organization that resides within the Government of Canada s Department of Natural Resources, and supports mapping projects and science investigations. PCSP is highlighted throughout the presentation so a description of mandate, budgets, and support infrastructure is warranted. In Part II, the presenter describes the planning required in advance of scientific deployments carried out in the Canadian High Arctic from the perspective of government and university investigators. Field operations and challenges encountered while leading arctic field teams in fly camps are also described in this part of the presentation, with particular emphasis on the 2008 field season. Part III is a summary of preliminary results obtained from a Polar Survey questionnaire sent out to members of the Arctic research community in anticipation of the workshop. The last part of the talk is an update on the analog program at the Canadian Space Agency, specifically, the Canadian Analog Research Network (CARN) and current activities related to Analog missions, 2009-2010.

  2. Silurian pinnacle reefs of the Canadian Arctic

    SciTech Connect

    De Freitas, T.A.; Dixon, O.A. ); Mayr, U. )

    1993-04-01

    Pinnacle reefs are commonly an attractive target for oil exploration because they are usually porous carbonate bodies entombed in impervious, deep-water shales that provide both the source and the seal for hydrocarbons. Silurian pinnacle reefs, the first described in the Canadian Arctic Archipelago, are exposed on Ellesmere and Devon Islands. Two main reef trends occur, one of early middle Llandovery to middle Ludlow age and a second of middle Ludlow to Late Silurian or Early Devonian age. Reefs of both phases contain lime mudstone cores: some are stromatactoid-rich and others consist predominantly of microbialite-rich lime mudstone or microbial boundstone. Facies sequences of both reef phases show evidence of upward-shallowing overall, but, in the older reefs, isochronous capping facies are dominated either by coral-mirian or by stromatoporoid boundstone and floatstone. This difference perhaps reflects variation in wave stress and apparent ability of a few corals,thickly encrusted by or associated with microbial boundstone and skeletal algae, to withstand greater wave energy than a stromatoporoid-coral-rich reef community. These reefs constitute one of the bright prospects of hydrocarbon exploration in rocks of the Franklinian succession. 43 refs., 9 figs.

  3. The Canadian Analogue Research Network (CARN): Opportunities for Mars Analogue Studies in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Osinski, G. R.; Berinstain, A.; Lebeuf, M.; Léveillé, R.

    2006-10-01

    The Canadian Analogue Research Network has been established by the Canadian Space Agency. This network of analogue sites, many of which are in the Arctic, provides a unique opportunity to further our understanding of the polar regions of Earth and Mars.

  4. Remagnetization and Cementation of Unconsolidated Sediments in the Mallik 5L-38 Well (Canadian Arctic) by Solute Exclusion During Gas Hydrate Formation

    NASA Astrophysics Data System (ADS)

    Hamilton, T. S.; Enkin, R. J.; Esteban, L.

    2007-05-01

    Bulk magnetic properties provide a sensitive measure of sedimentary diagenesis related to the stability and growth of gas hydrates. The deposit at Mallik (Mackenzie Delta, Canadian Arctic) occurs in unconsolidated Tertiary sands, but is absent in interstratified silt layers. A detailed sampling of the JAPEX/JNOC/GSC Mallik 5L-38 core tested the use of magnetic properties for detecting diagenetic changes related to the hydrate. Petrographic studies reveal that the sands are well sorted and clean, with quartz > chert >> muscovite and little fines content. Excepting a few rare bands of indurated dolomite in the midst of the gas hydrate zone, there is little or no cementation in the sands. Detrital magnetite is the dominant magnetic mineral, comprising up to a few percent of the sand grain population. In contrast, the muddier layers have a somewhat different detrital grain composition, richer in lithic (sedimentary and metamorphic) grains, feldspar, and clays. They are extensively diagenetically altered (to as much as 30- 40%) and cemented with carbonates, clays, chlorite and the iron sulphide greigite (the dominant magnetic mineral). The greigite is recognized by its isotropic creamy-white reflectance, cubic to prismatic habit, and characteristic tarnish to faintly bluish bireflectant mackinawite. Habits range from disseminated cubes and colliform masses to inflationary massive sulphide veins and clots. Rare detrital grains of magnetite were observed among the silt grains, but never in a reaction relationship or overgrown. Instead the greigite has nucleated separately, in tensional fractures and granular masses up to 4 mm across. In this particular sediment sequence, being so quartz and chert rich, there is insufficient local source for the introduced cements (calcite, dolomite, greigite, clays, jarosite), so ions must have been introduced by fluid flow. Magnetic studies reveal a bi-modal character related to the lithology (sands versus silts) and their magnetic

  5. Mercury in the Canadian Arctic terrestrial environment: an update.

    PubMed

    Gamberg, Mary; Chételat, John; Poulain, Alexandre J; Zdanowicz, Christian; Zheng, Jiancheng

    2015-03-15

    Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in the Canadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (<5 ng L(-1)), and methylmercury (MeHg) levels in terrestrial snow are also generally low (<0.1 ng L(-1)). On average, THg concentrations in snow on Canadian Arctic glaciers are much lower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase in the early 1990 s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (<5 μg g(-1) dry weight) in their tissues, although caribou (Rangifer tarandus) can have higher Hg because they consume large amounts of lichen. THg concentrations in the Yukon's Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades. PMID:24861531

  6. Mercury in the Canadian Arctic terrestrial environment: an update.

    PubMed

    Gamberg, Mary; Chételat, John; Poulain, Alexandre J; Zdanowicz, Christian; Zheng, Jiancheng

    2015-03-15

    Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in the Canadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (<5 ng L(-1)), and methylmercury (MeHg) levels in terrestrial snow are also generally low (<0.1 ng L(-1)). On average, THg concentrations in snow on Canadian Arctic glaciers are much lower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase in the early 1990 s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (<5 μg g(-1) dry weight) in their tissues, although caribou (Rangifer tarandus) can have higher Hg because they consume large amounts of lichen. THg concentrations in the Yukon's Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades.

  7. Variability of phytoplankton light absorption in Canadian Arctic seas

    NASA Astrophysics Data System (ADS)

    Brunelle, Corinne B.; Larouche, Pierre; Gosselin, Michel

    Phytoplankton light absorption spectra (aϕ(λ)) were measured in the Canadian Arctic (i.e., the Amundsen Gulf, Canadian Arctic Archipelago, northern Baffin Bay and the Hudson Bay system) to improve algorithms used in remote-sensing models of primary production. The absorption by algae, dominated by picophytoplankton (<5 μm), was not the major light absorption factor in the four provinces; the colored dissolved organic matter (CDOM) contributed up to 70% of total light absorption. During the fall, the low total chlorophyll a-specific aϕ*(443) (aϕ(443)/TChl a) coefficients of the Canadian High Arctic were associated with photoacclimation processes (i.e., the package effect) occurring in light-limited environments. Low light availability and high proportion of CDOM (absorbing strongly the ultraviolet) seem to allow the growth of phytoplankton with accessory pigments absorbing light at longer wavelengths. The ratio of photoprotective and photosynthetic carotenoids (PPC:PSC) was inversely proportional with the salinity and the cell size, and mostly decreases throughout the Canadian High Arctic during fall. In return, the highest TChl a-specific phytoplankton light absorption coefficients at the blue peak (aϕ*(443)) were observed in the Hudson Bay system from September to October (i.e., fall) as well as in the Amundsen Gulf from May to July (i.e., spring/summer). These results will ultimately allow the accurate monitoring of phytoplankton biomass and productivity evolution that is likely to take place as a result of the fast-changing Arctic environment.

  8. Organochlorine contaminants in narwhal (Monodon monoceros) from the Canadian Arctic.

    PubMed

    Muir, D C; Ford, C A; Grift, N P; Stewart, R E; Bidleman, T F

    1992-01-01

    Organochlorine pesticides (DDT, chlordane, polychlorinated camphenes (PCCs), dieldrin, hexachloroheclohexanes (SigmaHCH), mirex), polychlorinated biphenyl congeners (PCBs) and chlorobenzenes (SigmaCBz) were determined in blubber and liver of narwhal (Monodon monoceros) collected during 1982-1983 from Pond Inlet on northern Baffin Island in the Canadian Arctic. PCCs were the predominate organochlorines in narwhal blubber, ranging in concentration from 2990 to 13 200 ng g(-1) (wet wt) in males and from 1910 to 8390 ng g(-1) in females. PCCs consisted of two major components, an octachlorobornane and a nonachlorobornane with gas chromatographic retention times of 1.05 and 1.22, relative to 4,4'-DDE. SigmaPCB concentrations in blubber ranged from 2250 to 7290 ng g(-1) in males and from 894 to 5710 ng g(-1) in females. Seven PCB congeners (tetra-, penta- and hexachlorobiphenyls) accounted for 45% of total PCB (SigmaPCB) in narwhal blubber. Narwhal had 1.4- to 8.6-fold higher ratios of tetra- and pentachlorobiphenyls to PCB-153 (2,2',4,4',5,5'-hexachlorobiphenyl), lower 4,4'-DDE/SigmaDDT ratios and lower proportions of trans-nonachlor to total chlordane components than reported for odontocetes living in more contaminated environments. Mean SigmaPCB concentrations in narwhal were 6- to 15-fold lower than in dolphins from the Canadian east coast and belugas from the St Lawrence River estuary, respectively, while PCC levels were from 4- to about 2-fold lower, and SigmaHCH, dieldrin and SigmaCBz differed by <2-fold. The pattern of organochlorines in narwhal tissues suggests they are exposed to proportionally more volatile compounds, and may have less capacity to metabolize some of these compounds, relative to odontocetes living nearer sources of these contaminants. PMID:15092019

  9. Early Carboniferous (Visean) lacustrine oil shale in Canadian Arctic archipelago

    SciTech Connect

    Davies, G.R.; Nassichuk, W.W.

    1988-01-01

    The Lower Carboniferous (Visean) Emma Fiord Formation in the Canadian Arctic Archipelago is an oil shale of lacustrine origin composed of black carbonaceous shale, siltstone, and marlstone with interbedded sandstone, conglomerate, and oolitic and algal limestones. At Kleybolte Peninsula on Ellesmere Island, the Emma Fiord Formation was deposited on the tectonically active northwestern rim of the Sverdrup basin; it is now thermally overmature and well beyond the dry gas zone of organic maturation (vitrinite reflectance approx. = 5.0). In contrast, the Emma Fiord sequence on Grinnell Peninsula, Devon Island, near the southern edge of the Sverdrup basin, is immature to marginally mature (vitrinite reflectance = 0.26-0.44) and is composed predominantly of liptinite-rich oil shale. These kerogen-rich rocks contain a high volume of microcrystalline calcite and compositionally are marlstones. The Emma Fiord oil shales were deposited in lakes formed immediately prior to or possibly synchronous with the initiation of rifting in the Sverdrup basin. Syntectonic red-bed conglomerates derived from uplifted horst blocks directly overlie the Emma Fiord rocks. A few beds of conglomerate and sandstone in the upper part of the Emma Fiord Formation possibly record the onset of faulting. The formation closely resembles contemporaneous sequences in northern Alaska, Yukon Territory, Greenland, and Spitsbergen. Clearly, similar tectonic and paleoclimatic factors influenced sedimentation over this area in the Early Carboniferous, with the Sverdrup basin locations lying within 10/sup 0/-15/sup 0/ of the paleoequator. 11 figures, 2 tables.

  10. Environmental contaminants and human health in the Canadian Arctic.

    PubMed

    Donaldson, S G; Van Oostdam, J; Tikhonov, C; Feeley, M; Armstrong, B; Ayotte, P; Boucher, O; Bowers, W; Chan, L; Dallaire, F; Dallaire, R; Dewailly, E; Edwards, J; Egeland, G M; Fontaine, J; Furgal, C; Leech, T; Loring, E; Muckle, G; Nancarrow, T; Pereg, D; Plusquellec, P; Potyrala, M; Receveur, O; Shearer, R G

    2010-10-15

    The third Canadian Arctic Human Health Assessment conducted under the Canadian Northern Contaminants Program (NCP), in association with the circumpolar Arctic Monitoring and Assessment Programme (AMAP), addresses concerns about possible adverse health effects in individuals exposed to environmental contaminants through a diet containing country foods. The objectives here are to: 1) provide data on changes in human contaminant concentrations and exposure among Canadian Arctic peoples; 2) identify new contaminants of concern; 3) discuss possible health effects; 4) outline risk communication about contaminants in country food; and 5) identify knowledge gaps for future contaminant research and monitoring. The nutritional and cultural benefits of country foods are substantial; however, some dietary studies suggest declines in the amount of country foods being consumed. Significant declines were found for most contaminants in maternal blood over the last 10 years within all three Arctic regions studied. Inuit continue to have the highest levels of almost all persistent organic pollutants (POPs) and metals among the ethnic groups studied. A greater proportion of people in the East exceed Health Canada's guidelines for PCBs and mercury, although the proportion of mothers exceeding these guidelines has decreased since the previous assessment. Further monitoring and research are required to assess trends and health effects of emerging contaminants. Infant development studies have shown possible subtle effects of prenatal exposure to heavy metals and some POPs on immune system function and neurodevelopment. New data suggest important beneficial effects on brain development for Inuit infants from some country food nutrients. The most successful risk communication processes balance the risks and benefits of a diet of country food through input from a variety of regional experts and the community, to incorporate the many socio-cultural and economic factors to arrive at a risk

  11. Vegetation greening in the Canadian Arctic related to decadal warming.

    PubMed

    Jia, Gensuo J; Epstein, Howard E; Walker, Donald A

    2009-12-01

    This study is presented within the context that climate warming and sea-ice decline has been occurring throughout much of the Arctic over the past several decades, and that terrestrial ecosystems at high latitudes are sensitive to the resultant alterations in surface temperatures. Results are from analyzing interannual satellite records of vegetation greenness across a bioclimate gradient of the Canadian Arctic over the period of 1982-2006. Here, we combine multi-scale sub-pixel analysis and remote sensing time-series analysis to investigate recent decadal changes in vegetation greenness along spatial gradients of summer temperature and vegetation. Linear autoregression temporal analysis of vegetation greenness was performed with relatively "pure" vegetation pixels of Advanced Very High Resolution Radiometer (AVHRR) data, spanning Low Arctic, High Arctic and polar desert ecosystems. Vegetation greenness generally increased over tundra ecosystems in the past two decades. Peak annual greenness increased 0.49-0.79%/yr over the High Arctic where prostrate dwarf shrubs, forbs, mosses and lichens dominate and 0.46-0.67%/yr over the Low Arctic where erect dwarf shrubs and graminoids dominate. However, magnitudes of vegetation greenness differ with length of time series and periods considered, indicating a nonlinear response of terrestrial ecosystems to climate change. The decadal increases of greenness reflect increasing vegetation production during the peak of the growing season, and were likely driven by the recent warming.

  12. The Arctic--A Global Hot Spot: Resources for Teaching the Geography of the Contemporary Canadian Arctic

    ERIC Educational Resources Information Center

    Arntzen, Betsy; Sotherden, Amy

    2011-01-01

    Canadian geography is a fascinating topic, particularly the Canadian North. The North is central to Canadian identity as can be seen by the choice of the far north "inukshuk" standing stones as the emblem for the 2010 Winter Olympics held in Vancouver, southern British Columbia. Canada's Arctic is receiving increasing attention by media,…

  13. Literacy Lives Here: Using Video and Dialogue to Promote and Celebrate Adult and Literacy Education in the Canadian Western Arctic

    ERIC Educational Resources Information Center

    Robinson, Suzanne

    2009-01-01

    The Canadian North, one of the most isolated parts of the world, has been subject to increased scrutiny as a source of untapped oil and gas, a global warming harbinger and casualty, and a center of international sovereignty debate. What is often forgotten is that in addition to a resource bed and a border, the Arctic is first a homeland--a…

  14. New vascular plant records for the Canadian Arctic Archipelago

    PubMed Central

    Gillespie, Lynn J.; Saarela, Jeffery M.; Sokoloff, Paul C.; Bull, Roger D.

    2015-01-01

    Abstract The Canadian Arctic Archipelago is a vast region of approximately 1,420,000 km2, with a flora characterized by low species diversity, low endemicity, and little influence by alien species. New records of vascular plant species are documented here based on recent fieldwork on Victoria and Baffin Islands; additional records based on recent literature sources are mentioned. This paper serves as an update to the 2007 publication Flora of the Canadian Arctic Archipelago, and brings the total number of vascular plants for the region to 375 species and infraspecific taxa, an increase of 7.7%. Three families (Amaranthaceae, Juncaginaceae, Pteridaceae) and seven genera (Cherleria L., Cryptogramma R. Br., Platanthera Rich., Sabulina Rchb., Suaeda Forssk. ex J.F. Gmel., Triglochin L., Utricularia L.) are added to the flora, and one genus is deleted (Minuartia L.). Five species are first records for Nunavut (Arenaria longipedunculata Hultén, Cryptogramma stelleri (S.G. Gmel.) Prantl, Puccinellia banksiensis Consaul, Saxifraga eschscholtzii Sternb., Utricularia ochroleuca R.W. Hartm.) PMID:26311505

  15. Perfluoroalkyl acids in the Atlantic and Canadian Arctic Oceans.

    PubMed

    Benskin, Jonathan P; Muir, Derek C G; Scott, Brian F; Spencer, Christine; De Silva, Amila O; Kylin, Henrik; Martin, Jonathan W; Morris, Adam; Lohmann, Rainer; Tomy, Gregg; Rosenberg, Bruno; Taniyasu, Sachi; Yamashita, Nobuyoshi

    2012-06-01

    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 (∑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). ∑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 ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑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. PMID:22548373

  16. Sea ice of the northern Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Melling, Humfrey

    2002-11-01

    Existing information concerning the pack ice and relevant climate variables of the Canadian Arctic Archipelago north of Parry Channel is summarized. This knowledge is enhanced by newly available data on ice thickness derived from 123,703 drill holes completed during the 1970s. Pack ice in this area is a mix of multiyear, second-year, and first-year ice types, with the latter subordinate except in the southeast. Ice remains land fast for more than half the year, and summertime ice concentration is high (7-9 tenths). In a typical year, less than 20% of the old ice and 50% of the first-year ice melt. There are large interannual fluctuations in ice coverage and some suggestion of a decadal cycle. The average ice thickness in late winter is 3.4 m but subregional means reach 5.5 m. The pack is a mix of two populations, one consisting largely of multiyear ice imported from the zone of heavy ridging along the periphery of the Beaufort gyre and the other consisting of a mix of relatively undeformed first-year, second-year, and multiyear ice types that grow and age within the basin. The ice of the Sverdrup Basin is strongly influenced by a flux of heat (approximately 10 W m-2) that originates in the Atlantic-derived waters of the Arctic Ocean. The drift of ice through the basin is controlled in the present climate by the formation of stable ice bridges across connecting channels. The drift is episodic. Relaxation of these controls in a warmer climate may cause deterioration in ice conditions in Canadian Arctic waters.

  17. Environmental Drivers of the Canadian Arctic Megabenthic Communities

    PubMed Central

    Roy, Virginie; Iken, Katrin; Archambault, Philippe

    2014-01-01

    Environmental gradients and their influence on benthic community structure vary over different spatial scales; yet, few studies in the Arctic have attempted to study the influence of environmental gradients of differing spatial scales on megabenthic communities across continental-scales. The current project studied for the first time how megabenthic community structure is related to several environmental factors over 2000 km of the Canadian Arctic, from the Beaufort Sea to northern Baffin Bay. Faunal trawl samples were collected between 2007 and 2011 at 78 stations from 30 to 1000 m depth and patterns in biomass, density, richness, diversity, and taxonomic composition were examined in relation to indirect/spatial gradients (e.g., depth), direct gradients (e.g., bottom oceanographic variables), and resource gradients (e.g., food supply proxies). Six benthic community types were defined based on their biomass-based taxonomic composition. Their distribution was significantly, but moderately, associated with large-scale (100–1000 km) environmental gradients defined by depth, physical water properties (e.g., bottom salinity), and meso-scale (10–100 km) environmental gradients defined by substrate type (hard vs. soft) and sediment organic carbon content. We did not observe a strong decline of bulk biomass, density and richness with depth or a strong increase of those community characteristics with food supply proxies, contrary to our hypothesis. We discuss how local- to meso-scale environmental conditions, such as bottom current regimes and polynyas, sustain biomass-rich communities at specific locations in oligotrophic and in deep regions of the Canadian Arctic. This study demonstrates the value of considering the scales of variability of environmental gradients when interpreting their relevance in structuring of communities. PMID:25019385

  18. Trace elements in freshwater ecosystems in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Borg, H.

    2003-05-01

    The expedition Tundra North West 99 visited 17 sites across the Canadian Arctic in order to sample freshwater, sediments, soil and biotic compartments of the ecosystems. Trace metal concentrations were determined using ICP-MS. Dating of sediment profiles using ^137Cs showed a very low sedimentation rate in these lakes (<1 mm/yr). The lake waters were mostly well buffered with high pH and hardness, with the exception of lakes on Ellef Ringnes Island and Baffin Island. Trace metal concentrations in lake waters were generally low, but with some locally elevated concentrations. Trace metal profiles in sediments showed influence of catchment geology, indicated by elevated concentrations at some sites, e.g. NW Yukon. Increased concentrations of Cd, Hg, Zn, Pb, Tl and some other elements, found in recent sediment layers may indicate long-range airbome pollution. The elevated concentrations of e.g. Cd and Cu in the sediments and water at the Yukon site were also reflected in fish. Cd-concentrations in Arctic char liver were about 10 times higher than in other areas in the Arctic and in northern Sweden. Cd-concentrations in char liver were otherwise low with slightly elevated values in the more soft water lake at Baffin Island. Mercury concentrations in sediment at the Yukon site were 20 40 times higher than in the other lakes, whereas the concentration in fish muscle were still not elevated, which may be explained by the also elevated Se concentrations in the lake. The variations in Hgconcentrations in Arctic char were otherwise small, with the highest values at Ungava Peninsula and Ellesmere Island.

  19. Mercury Depletion Episode Studies in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Steffen, A.; Schroeder, W.; Hoenniger, G.; Platt, U.; Lawson, G.

    2001-12-01

    Episodic mercury depletion episodes were first recorded in Alert, Canada in 1995. Since this time, considerable research has been undertaken to further study this phenomenon. It has been found that there is an occurrence of fast photo-chemically induced reactions involving the oxidation of Hg (0) to Hg (II) during the springtime period in the high Arctic. Data from a cold regions pyrolysis unit (CRPU) have confirmed that particle-associated mercury (PM) and reactive gaseous mercury (RGM) are still present in the air during a mercury depletion event when Hg (0) concentration levels are very low. These more reactive species are less volatile and are more readily removed in the air and/or are deposited on the snow surfaces than Hg (0). In the winter and spring of 2000 in Alert, snow samples collected showed an almost 20 fold increase in mercury concentrations during the springtime period from the dark period. Air profiling measurements undertaken during the same time period have shown that Hg (0) is re-emitted from the snow pack surfaces both over land and the frozen Arctic Ocean near Alert. It is thought that free radical BrO is responsible for the destruction of ozone depletion episodes in the Arctic during springtime and increased concentrations from satellites have been measured during these times. Ground level in situ measurements taken over the frozen ocean during depletion events showed an anti-correlation between Hg (0) and BrO concentrations during MDEs. In February 2001, continuous automated RGM and PM measurements were initiated to further study this phenomenon in parallel with the CRPU to measure total atmospheric mercury concentrations in ambient air in the Canadian Arctic during springtime depletion events. A summary of findings from these studies will be presented.

  20. The Canadian Arctic ACE/OSIRIS Validation Project at PEARL: Validating Satellite Observations Over the High Arctic

    NASA Astrophysics Data System (ADS)

    Walker, Kaley A.; Strong, Kimberly; Fogal, Pierre F.; Drummond, James R.

    2016-04-01

    Ground-based measurements provide critical data for the validation of satellite retrievals of atmospheric trace gases and for the assessment of long-term stability of these measurements. As of February 2016, the Canadian-led Atmospheric Chemistry Experiment (ACE) satellite mission has been making measurements of the Earth's atmosphere for nearly twelve years and Canada's Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite has been operating for fourteen years. As ACE and OSIRIS operations have extended beyond their planned two-year missions, there is an ongoing need to validate the trace gas data profiles from the ACE-Fourier Transform Spectrometer (ACE-FTS), the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (ACE-MAESTRO) and OSIRIS. In particular, validation comparisons are needed during Arctic springtime to understand better the measurements of species involved in stratospheric ozone chemistry. To this end, thirteen Canadian Arctic ACE/OSIRIS Validation Campaigns have been conducted during the spring period (February - April in 2004 - 2016) at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut (80N, 86W). For the past decade, these campaigns have been undertaken in collaboration with the Canadian Network for the Detection of Atmospheric Change (CANDAC). The spring period coincides with the most chemically active time of year in the Arctic, as well as a significant number of satellite overpasses. A suite of as many as 12 ground-based instruments, as well as frequent balloon-borne ozonesonde and radiosonde launches, have been used in each campaign. These instruments include: a ground-based version of the ACE-FTS (PARIS - Portable Atmospheric Research Interferometric Spectrometer), a terrestrial version of the ACE-MAESTRO, a SunPhotoSpectrometer, two CANDAC zenith-viewing UV-visible grating spectrometers, a Bomem DA8 Fourier transform spectrometer

  1. Indicators of changing landscape wetness in the western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Marsh, P.; de Jong, T.; Walker, B.

    2015-12-01

    The landscape of the western Canadian arctic has been changing over the last 5 decades in response to warming air temperatures and decreasing precipitation. Changes include thinner snowcover, decreased river and lake ice thickness, deepening active layer, increasing thaw slumping, and expanding shrub cover for example. Although there are no long term data sets to consider changes in soil wetness in this region, changes in surface moisture can be considered through analysis of both long term stream discharge records and remote sensing of tundra ponds and lakes. In this paper, we will use these long term records in order to explore past changes to this environment. In addition, we will outline details of ongoing observations at long term observatories and modelling efforts to consider the controls on future changes in wetness.

  2. Barium and Carbon fluxes in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Thomas, H.; Shadwick, E. H.; Woule Ebongue, V.; Lansard, B.; Navez, J.; Gratton, Y.; Prowe, F.; Mucci, A.; Chierici, M.; Fransson, A.; Papakyriakou, T. N.; Sternberg, E.; Miller, L. A.

    2010-12-01

    The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Barium displays a nutrient-type behavior with the highest concentrations observed at river mouths. The water column maximum is located at the base of the surface layer with lower concentrations above and below. The lowest concentrations are found in water masses of Atlantic origin, and Ba concentrations decrease eastward through the Canadian Arctic Archipelago. A three end-member mixing model comprising fresh water from sea-ice melt and rivers, as well as upper halocline water, was used to establish their relative contributions to the surface waters of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the Ba depletion by particle sinking and subsequently estimate the carbon export production. In the upper 50 m of the water column of Amundsen Gulf, riverine Ba accounts for up to 15% of the dissolved Ba inventory, whereas up to 20% of the dissolved Ba inventory is depleted by barite (BaSO4) formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba is moderate. Assuming a fixed organic carbon to barite flux ratio, carbon export out of the surface layer is estimated at 2 mol C m-2 yr-1. Finally, we propose a climatological carbon budget for the Amundsen Gulf based on recent literature data and our findings, the latter bridging the surface and subsurface water carbon cycles. This work is a contribution to the Canadian IPY programs CFL and GEOTRACES, to ArcticNet as well as to the IGBP/IHDP core project LOICZ.

  3. Pollution in the Summertime Canadian High Arctic observed during NETCARE 2014: Investigation of origin and composition

    NASA Astrophysics Data System (ADS)

    Köllner, Franziska; Schneider, Johannes; Bozem, Heiko; Hoor, Peter; Willis, Megan; Burkart, Julia; Leaitch, Richard; Abbatt, Jon; Herber, Andreas; Borrmann, Stephan

    2015-04-01

    The clean and sensitive Arctic atmosphere is influenced by transport of air masses from lower latitudes that bring pollution in the form of aerosol particles and trace gases into the Arctic regions. However, the transport processes causing such pollution events are yet not sufficiently well understood. Here we report on results from the aircraft campaign NETCARE 2014 that took place in July 2014 in Resolute Bay, Nunavut (Canada) as part of the "Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environment" (NETCARE). These airborne measurements add to only a very few of such measurements conducted in the Arctic during the summertime. The instrumentation on board the research aircraft Polar 6 (operated by the Alfred Wegener Institute for Polar and Marine Research) included a large set of physico-chemical aerosol analysis instruments, several trace gas measurements and basic meteorological parameters. Here we focus on observed pollution events that caused elevated trace gas and aerosol concentrations in the summertime Canadian High Arctic between 50 and 3500 m. In order to better understand the chemical composition and the origin of those polluted air masses, we use single particle aerosol composition obtained using the Aircraft-based Laser Ablation Aerosol Mass Spectrometer (ALABAMA), combined with aerosol size distributions and number concentrations from an Optical Particle Counter as well as trace gas measurements of CO and CO2. CO and CO2 are important tracers to study pollution events, which are connected to anthropogenic and non-anthropogenic combustion processes, respectively biomass burning and fossil fuel combustion. The ALABAMA provides a detailed single particle aerosol composition analysis from which we identify different particle types like soot-, biomass burning-, organics-, diesel exhaust- and metallic particles. The measurements were compared to Lagrangian models like FLEXPART and LAGRANTO to find the pollution sources

  4. Carbon and Carbon Isotope Cycling in the Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Mol, Jacoba; Thomas, Helmuth

    2016-04-01

    Increasing carbon dioxide levels in the atmosphere are having drastic effects on the global oceans. The Arctic Ocean is particularly susceptible to change as warming, sea-ice loss and a weak buffering capacity all influence this complicated semi-enclosed sea. In order to investigate the inorganic carbon system in the Canadian Arctic, water samples were collected in the Beaufort Sea, on the Alaskan shelf, at the Mackenzie river delta, and in Amundsen Gulf during the summer of 2014 and were analyzed for dissolved inorganic carbon (DIC), total alkalinity (TA), DI13C and 18O isotopes. Carbon isotopes are used to investigate the role of biological production on the uptake and transfer of inorganic carbon to depth. A preferential uptake of the lighter 12C relative to the heavier 13C isotope during biological production leads to a fractionation of the 13C/12C isotopes in both the organic matter and the water column. This results in an enrichment of DI13C in the high productivity surface waters and a depletion of DI13C at depth. Physical processes including freshwater input, brine rejection, and water mass mixing are investigated through the measurement of oxygen isotopes. Differences in the carbon system across the study area due to both biological and physical processes are assessed using depth profiles of DI13C and related carbon system parameters.

  5. Organophosphate Esters in Canadian Arctic Air: Occurrence, Levels and Trends.

    PubMed

    Sühring, Roxana; Diamond, Miriam L; Scheringer, Martin; Wong, Fiona; Pućko, Monika; Stern, Gary; Burt, Alexis; Hung, Hayley; Fellin, Philip; Li, Henrik; Jantunen, Liisa M

    2016-07-19

    Fourteen organophosphate esters (OPEs) were measured in the filter fraction of 117 active air samples from yearly ship-based sampling campaigns (2007-2013) and two land-based stations in the Canadian Arctic, to assess trends and long-range transport potential of OPEs. Four OPEs were detected in up to 97% of the samples, seven in 50% or less of the samples, and three were not detected. Median concentrations of ∑OPEs were 237 and 50 pg m(-3) for ship- and land-based samples, respectively. Individual median concentrations ranged from below detection to 119 pg m(-3) for ethanol, 2-chloro-, phosphate (3:1) (TCEP). High concentrations of up to 2340 pg m(-3) were observed for Tri-n-butyl phosphate (TnBP) at a land-based sampling location in Resolute Bay from 2012, whereas it was only detected in one ship-based sample at a concentration below 100 pg m(-3). Concentrations of halogenated OPEs seemed to be driven by river discharge from the Nelson and Churchill Rivers (Manitoba) and Churchill River and Lake Melville (Newfoundland and Labrador). In contrast, nonhalogenated OPE concentrations appeared to have diffuse sources or local sources close to the land-based sampling stations. Triphenyl phosphate (TPhP) showed an apparent temporal trend with a doubling-time of 11 months (p = 0.044). The results emphasize the increasing relevance of halogenated and nonhalogenated OPEs as contaminants in the Arctic.

  6. Organophosphate Esters in Canadian Arctic Air: Occurrence, Levels and Trends.

    PubMed

    Sühring, Roxana; Diamond, Miriam L; Scheringer, Martin; Wong, Fiona; Pućko, Monika; Stern, Gary; Burt, Alexis; Hung, Hayley; Fellin, Philip; Li, Henrik; Jantunen, Liisa M

    2016-07-19

    Fourteen organophosphate esters (OPEs) were measured in the filter fraction of 117 active air samples from yearly ship-based sampling campaigns (2007-2013) and two land-based stations in the Canadian Arctic, to assess trends and long-range transport potential of OPEs. Four OPEs were detected in up to 97% of the samples, seven in 50% or less of the samples, and three were not detected. Median concentrations of ∑OPEs were 237 and 50 pg m(-3) for ship- and land-based samples, respectively. Individual median concentrations ranged from below detection to 119 pg m(-3) for ethanol, 2-chloro-, phosphate (3:1) (TCEP). High concentrations of up to 2340 pg m(-3) were observed for Tri-n-butyl phosphate (TnBP) at a land-based sampling location in Resolute Bay from 2012, whereas it was only detected in one ship-based sample at a concentration below 100 pg m(-3). Concentrations of halogenated OPEs seemed to be driven by river discharge from the Nelson and Churchill Rivers (Manitoba) and Churchill River and Lake Melville (Newfoundland and Labrador). In contrast, nonhalogenated OPE concentrations appeared to have diffuse sources or local sources close to the land-based sampling stations. Triphenyl phosphate (TPhP) showed an apparent temporal trend with a doubling-time of 11 months (p = 0.044). The results emphasize the increasing relevance of halogenated and nonhalogenated OPEs as contaminants in the Arctic. PMID:27309668

  7. Mercury in the marine environment of the Canadian Arctic: review of recent findings.

    PubMed

    Braune, Birgit; Chételat, John; Amyot, Marc; Brown, Tanya; Clayden, Meredith; Evans, Marlene; Fisk, Aaron; Gaden, Ashley; Girard, Catherine; Hare, Alex; Kirk, Jane; Lehnherr, Igor; Letcher, Robert; Loseto, Lisa; Macdonald, Robie; Mann, Erin; McMeans, Bailey; Muir, Derek; O'Driscoll, Nelson; Poulain, Alexandre; Reimer, Ken; Stern, Gary

    2015-03-15

    This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine regions in the circumpolar Arctic. Mass balance models have been developed to provide quantitative estimates of THg fluxes into and out of the Arctic Ocean and Hudson Bay. Several recent studies on Hg biomagnification have improved our understanding of trophic transfer of Hg through marine food webs. Over the past several decades, Hg concentrations have increased in some marine biota, while other populations showed no temporal change. Marine biota also exhibited considerable geographic variation in Hg concentrations with ringed seals, beluga and polar bears from the Beaufort Sea region having higher Hg concentrations compared with other parts of the Canadian Arctic. The drivers of these variable patterns of Hg bioaccumulation, both regionally and temporally, within the Canadian Arctic remain unclear. Further research is needed to identify the underlying processes including the interplay between biogeochemical and food web processes and climate change. PMID:24953756

  8. Mercury in the marine environment of the Canadian Arctic: review of recent findings.

    PubMed

    Braune, Birgit; Chételat, John; Amyot, Marc; Brown, Tanya; Clayden, Meredith; Evans, Marlene; Fisk, Aaron; Gaden, Ashley; Girard, Catherine; Hare, Alex; Kirk, Jane; Lehnherr, Igor; Letcher, Robert; Loseto, Lisa; Macdonald, Robie; Mann, Erin; McMeans, Bailey; Muir, Derek; O'Driscoll, Nelson; Poulain, Alexandre; Reimer, Ken; Stern, Gary

    2015-03-15

    This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine regions in the circumpolar Arctic. Mass balance models have been developed to provide quantitative estimates of THg fluxes into and out of the Arctic Ocean and Hudson Bay. Several recent studies on Hg biomagnification have improved our understanding of trophic transfer of Hg through marine food webs. Over the past several decades, Hg concentrations have increased in some marine biota, while other populations showed no temporal change. Marine biota also exhibited considerable geographic variation in Hg concentrations with ringed seals, beluga and polar bears from the Beaufort Sea region having higher Hg concentrations compared with other parts of the Canadian Arctic. The drivers of these variable patterns of Hg bioaccumulation, both regionally and temporally, within the Canadian Arctic remain unclear. Further research is needed to identify the underlying processes including the interplay between biogeochemical and food web processes and climate change.

  9. Arctic Oil and Natural Gas Potential

    EIA Publications

    2009-01-01

    This paper examines the discovered and undiscovered Arctic oil and natural gas resource base with respect to their location and concentration. The paper also discusses the cost and impediments to developing Arctic oil and natural gas resources, including those issues associated with environmental habitats and political boundaries.

  10. Invasion, establishment, and range expansion of two parasitic nematodes in the Canadian Arctic

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate warming is modifying host-parasite interactions in the Arctic. Invasion of an arctic island by protostrongylid nematodes appears mediated by sporadic dispersal of muskoxen and seasonal migration by caribou from the Canadian mainland. A newly permissive environment likely facilitated initial ...

  11. Atmospheric mercury in the Canadian Arctic. Part II: insight from modeling.

    PubMed

    Dastoor, Ashu; Ryzhkov, Andrew; Durnford, Dorothy; Lehnherr, Igor; Steffen, Alexandra; Morrison, Heather

    2015-03-15

    A review of mercury in the Canadian Arctic with a focus on field measurements is presented in part I (see Steffen et al., this issue). Here we provide insights into the dynamics of mercury in the Canadian Arctic from new and published mercury modeling studies using Environment Canada's mercury model. The model simulations presented in this study use global anthropogenic emissions of mercury for the period 1995-2005. The most recent modeling estimate of the net gain of mercury from the atmosphere to the Arctic Ocean is 75 Mg year(-1) and the net gain to the terrestrial ecosystems north of 66.5° is 42 Mg year(-1). Model based annual export of riverine mercury from North American, Russian and all Arctic watersheds to the Arctic Ocean are in the range of 2.8-5.6, 12.7-25.4 and 15.5-31.0 Mg year(-1), respectively. Analysis of long-range transport events of Hg at Alert and Little Fox Lake monitoring sites indicates that Asia contributes the most ambient Hg to the Canadian Arctic followed by contributions from North America, Russia, and Europe. The largest anthropogenic Hg deposition to the Canadian Arctic is from East Asia followed by Europe (and Russia), North America, and South Asia. An examination of temporal trends of Hg using the model suggests that changes in meteorology and changes in anthropogenic emissions equally contribute to the decrease in surface air elemental mercury concentrations in the Canadian Arctic with an overall decline of ~12% from 1990 to 2005. A slow increase in net deposition of Hg is found in the Canadian Arctic in response to changes in meteorology. Changes in snowpack and sea-ice characteristics and increase in precipitation in the Arctic related with climate change are found to be primary causes for the meteorology-related changes in air concentrations and deposition of Hg in the region. The model estimates that under the emissions reduction scenario of worldwide implementation of the best emission control technologies by 2020, mercury

  12. A Pliocene chronostratigraphy for the Canadian western and high Arctic

    NASA Astrophysics Data System (ADS)

    Gosse, John; Braschi, Lea; Rybczynski, Natalia; Lakeman, Thomas; Zimmerman, Susan; Finkel, Robert; Barendregt, Rene; Matthews, John

    2014-05-01

    The Beaufort Formation comprises an extensive (1200 km long, more than 1 km thick) clastic wedge that formed during the Pliocene along the western Canadian Arctic Archipelago (CAA). In the western Arctic, the Ballast Brook (BB) site on Banks Is. exposes more than 20 km of section through the sandy and pebble sandy braided stream deposits with detrital organic beds. Farther north, Beaufort Fm fluvial and estuarine facies have been examined on Meighen Is. In the high Arctic, high terrace gravels (450 m high surface) at the Fyles Leaf Bed (FLB) and Beaver Pond (BP) sites on Ellesmere Is. are not considered part of the Beaufort Fm but have similar paleoenvironmental records. Fossil plant and faunal material from these sediments is often very well preserved and provides evidence of a boreal-type forest and peatlands. The BP fossil site preserves the remains of fossil vertebrates including fish, frog, horse, beaver, deerlet, and black bear, consistent with a boreal type forest habitat. The FLB site has recently yielded the first fossil evidence for a High Arctic camel, identified with the help of collagen fingerprinting from a fragmentary limb bone (tibia). Paleoenvironmental reconstruction of the Ellesmere sites has yielded a Mean Annual Temperature of between 14 to 22 degrees Celsius warmer than today. Minimum cosmogenic nuclide burial ages of 3.4 and 3.8 Ma obtained for the BP and FLB sites, respectively, are consistent with vertebrate and floral biostratigraphic evidence. The paleoenvironmental records from the Beaufort Fm in the western CAA sites have revealed a similar ecosystem with noteworthy differences in MAT and perhaps seasonality. New burial ages from Meighen Is. indicate a maximum age of 6.1 Ma, consistent with yet much older than previous age estimates, but supportive of paleomagnetic and biostratigraphy at the same location. The age differences may account for some of the interpreted variations in paleoenvironments, in addition to spatial differences in

  13. Gas line construction in frigid Canadian winter

    SciTech Connect

    Not Available

    1983-01-01

    Construction of a 128-mile, 42-in. gas transmission line through Precambrian rock formations in the Canadian shield proved difficult for contractors on TransCanada Pipeline's expansion program. Multiple construction problems included severe cold weather (-40/sup 0/F), a right-of-way sited midway between two live natural gas lines, and a system installed in eight different loops stretching almost 500 miles from one and to the other.

  14. Trends and variability in summer sea ice cover in the Canadian Arctic based on the Canadian Ice Service Digital Archive

    NASA Astrophysics Data System (ADS)

    Howell, S.; Tivy, A. C.; Alt, B.; McCourt, S.; Chagnon, R.; Crocker, G.; Carrieres, T. G.; Yackel, J.

    2010-12-01

    The Canadian Ice Service Digital Archive (CISDA) is a compilation of weekly ice charts that cover Canadian Waters; the data set is continually updated and it extends back to the early 1960s. The ice charts are represent and integration of remotely sensed sea ice data, surface observations, airborne and ship reports, operational model results and the expertise of experience ice forecasters. Although the accuracy, type and detail of information far exceeds what is attainable from a single satellite source, errors and uncertainties in the data are non-uniform in both space and time. In part one of this study the main sources of uncertainty in the database are reviewed and the data are validated for use in climate studies. In part two, trends and variability in summer sea ice in the Canadian Arctic are investigated using CISDA. These data revealed that between 1968 and 2008, summer sea ice cover has decreased by 8.9% ± 3.1% per decade in Hudson Bay, 2.9% ± 1.2% per decade in the Canadian Arctic Archipelago, 8.9% ± 3.1% per decade in Baffin Bay, and 5.2% ± 2.4% per decade in the Beaufort Sea. In general, these reductions in sea ice cover are linked to increases in early summer surface air temperature (SAT); significant increases in SAT were observed in every season and with the exception of the Hudson Bay region they are consistently greater than the pan-Arctic change by up to ~0.2oC per decade. Within the Canadian Arctic Archipelago and Baffin Bay, the El Niño-Southern Oscillation (ENSO) index correlates well with multi-year ice coverage (positive correlation) and first-year ice coverage (negative correlation) suggesting that El Nino episodes precede summers with more multi-year ice and less first-year ice. Extending the trend calculations back to 1960 along the major shipping routes through the Canadian Arctic revealed significant decreases in summer sea ice coverage ranging between 11% and 15% per decade along the shipping route through Hudson Bay, the western

  15. Elevation Changes of Ice Caps in the Canadian Arctic Archipelago

    NASA Technical Reports Server (NTRS)

    Abdalati, W.; Krabill, W.; Frederick, E.; Manizade, S.; Martin, C.; Sonntag, J.; Swift, R.; Thomas, R.; Yungel, J.; Koerner, R.

    2004-01-01

    Precise repeat airborne laser surveys were conducted over the major ice caps in the Canadian Arctic Archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region. Our measurements reveal thinning at lower elevations (below 1600 m) on most of the ice caps and glaciers, but either very little change or thickening at higher elevations in the ice cap accumulation zones. Recent increases in precipitation in the area can account for the slight thickening where it was observed, but not for the thinning at lower elevations. For the northern ice caps on the Queen Elizabeth Islands, thinning was generally less than 0.5 m/yr , which is consistent with what would be expected from the warm temperature anomalies in the region for the 5-year period between surveys and appears to be a continuation of a trend that began in the mid 1980s. Further south, however, on the Barnes and Penny ice caps on Baffin Island, this thinning was much more pronounced at over 1 m/yr in the lower elevations. Here temperature anomalies were very small, and the thinning at low elevations far exceeds any associated enhanced ablation. The observations on Barnes, and perhaps Penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation, as has been previously suggested for Barnes Ice Cap. Based on the regional relationships between elevation and elevation-change in our data, the 1995-2000 mass balance for the region is estimated to be 25 cu km/yr of ice, which corresponds to a sea level increase of 0.064 mm/ yr . This places it among the more significant sources of eustatic sea level rise, though not as substantial as Greenland ice sheet, Alaskan glaciers, or the Patagonian ice fields.

  16. Barium and carbon fluxes in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Thomas, Helmuth; Shadwick, Elizabeth; Dehairs, Frank; Lansard, Bruno; Mucci, Alfonso; Navez, Jacques; Gratton, Yves; Prowe, Friederike; Chierici, Melissa; Fransson, Agneta; Papakyriakou, Tim N.; Sternberg, Erika; Miller, Lisa A.; Tremblay, Jean-ÉRic; Monnin, Christophe

    2011-09-01

    The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type behavior: the maximum water column concentration is located below the surface layer. The highest Ba concentrations are typically observed at river mouths, the lowest concentrations are found in water masses of Atlantic origin. Barium concentrations decrease eastward through the Canadian Arctic Archipelago. Barite (BaSO4) saturation is reached at the maximum dissolved Ba concentrations in the subsurface layer, whereas the rest of the water column is undersaturated. A three end-member mixing model comprising freshwater from sea-ice melt and rivers, as well as upper halocline water, is used to establish their relative contributions to the Ba concentrations in the upper water column of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the depletion of dissolved Ba by formation and sinking of biologically bound Ba (bio-Ba), from which we derive an estimate of the carbon export production. In the upper 50 m of the water column of the Amundsen Gulf, riverine Ba accounts for up to 15% of the available dissolved Ba inventory, of which up to 20% is depleted by bio-Ba formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba in the upper water column is moderate. Assuming a fixed organic carbon to bio-Ba flux ratio, carbon export out of the surface layer is estimated at 1.8 ± 0.45 mol C m-2 yr-1. Finally, we propose a climatological carbon budget for the Amundsen Gulf based on recent literature data and our findings, the latter bridging the surface and subsurface water carbon cycles.

  17. Methanogen community composition and rates of methane consumption in Canadian High Arctic permafrost soils.

    PubMed

    Allan, J; Ronholm, J; Mykytczuk, N C S; Greer, C W; Onstott, T C; Whyte, L G

    2014-04-01

    Increasing permafrost thaw, driven by climate change, has the potential to result in organic carbon stores being mineralized into carbon dioxide (CO2) and methane (CH4) through microbial activity. This study examines the effect of increasing temperature on community structure and metabolic activity of methanogens from the Canadian High Arctic, in an attempt to predict how warming will affect microbially controlled CH4 soil flux. In situ CO2 and CH4 flux, measured in 2010 and 2011 from ice-wedge polygons, indicate that these soil formations are a net source of CO2 emissions, but a CH4 sink. Permafrost and active layer soil samples were collected at the same sites and incubated under anaerobic conditions at warmer temperatures, with and without substrate amendment. Gas flux was measured regularly and indicated an increase in CH4 flux after extended incubation. Pyrosequencing was used to examine the effects of an extended thaw cycle on methanogen diversity and the results indicate that in situ methanogen diversity, based on the relative abundance of the 16S ribosomal ribonucleic acid (rRNA) gene associated with known methanogens, is higher in the permafrost than in the active layer. Methanogen diversity was also shown to increase in both the active layer and permafrost soil after an extended thaw. This study provides evidence that although High Arctic ice-wedge polygons are currently a sink for CH4, higher arctic temperatures and anaerobic conditions, a possible result of climate change, could result in this soil becoming a source for CH4 gas flux. PMID:24596286

  18. High Methylmercury in Arctic and Subarctic Ponds is Related to Nutrient Levels in the Warming Eastern Canadian Arctic.

    PubMed

    MacMillan, Gwyneth A; Girard, Catherine; Chételat, John; Laurion, Isabelle; Amyot, Marc

    2015-07-01

    Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L(-1)). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3-2.2 ng L(-1)) than polygonal ponds (0.1-0.3 ng L(-1)) or lakes (<0.1 ng L(-1)). High MeHg was measured in the bottom waters of Subarctic thaw ponds near Kuujjuarapik (0.1-3.1 ng L(-1)). High water MeHg concentrations in thaw ponds were strongly correlated with variables associated with high inputs of organic matter (DOC, a320, Fe), nutrients (TP, TN), and microbial activity (dissolved CO2 and CH4). Thawing permafrost due to Arctic warming will continue to release nutrients and organic carbon into these systems and increase ponding in some regions, likely stimulating higher water concentrations of MeHg. Greater hydrological connectivity from permafrost thawing may potentially increase transport of MeHg from thaw ponds to neighboring aquatic ecosystems.

  19. Monitoring Arctic Sea ice using ERTS imagery. [Bering Sea, Beaufort Sea, Canadian Archipelago, and Greenland Sea

    NASA Technical Reports Server (NTRS)

    Barnes, J. C.; Bowley, C. J.

    1974-01-01

    Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and other minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft.

  20. Mercury in freshwater ecosystems of the Canadian Arctic: recent advances on its cycling and fate.

    PubMed

    Chételat, John; Amyot, Marc; Arp, Paul; Blais, Jules M; Depew, David; Emmerton, Craig A; Evans, Marlene; Gamberg, Mary; Gantner, Nikolaus; Girard, Catherine; Graydon, Jennifer; Kirk, Jane; Lean, David; Lehnherr, Igor; Muir, Derek; Nasr, Mina; Poulain, Alexandre J; Power, Michael; Roach, Pat; Stern, Gary; Swanson, Heidi; van der Velden, Shannon

    2015-03-15

    The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic.

  1. Mercury in freshwater ecosystems of the Canadian Arctic: recent advances on its cycling and fate.

    PubMed

    Chételat, John; Amyot, Marc; Arp, Paul; Blais, Jules M; Depew, David; Emmerton, Craig A; Evans, Marlene; Gamberg, Mary; Gantner, Nikolaus; Girard, Catherine; Graydon, Jennifer; Kirk, Jane; Lean, David; Lehnherr, Igor; Muir, Derek; Nasr, Mina; Poulain, Alexandre J; Power, Michael; Roach, Pat; Stern, Gary; Swanson, Heidi; van der Velden, Shannon

    2015-03-15

    The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic. PMID:24993511

  2. Holocene paleoceanography of the northwest passage, Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Ledu, David; Rochon, André; de Vernal, Anne; St-Onge, Guillaume

    2010-12-01

    A series of cores (box and piston) were collected at 2 key locations in Lancaster Sound (cores 2004-804-009 BC and PC) and Barrow Strait (cores 2005-804-004 BC and PC) in the Canadian Arctic Archipelago to document the evolution of sea-surface conditions in the main axis of the Northwest Passage during the Holocene time period. Reconstruction of sea-surface parameters (summer temperature and salinity, duration of sea-ice cover) were estimated based on transfer functions using dinoflagellate cyst assemblages as proxy indicators. The chronology of these cores is based on calibrated AMS- 14C dates, 210Pb analyses, and correlations between paleomagnetic secular variations of the geomagnetic field and a predicted spherical harmonic model of the geomagnetic field (CALS7 K.2). Our age models for both cores indicate that 009 PC spans the last 11,100 cal BP, while 004 PC encompasses the last 10,800 cal BP. Calculated sedimentation rates are in the range of 43-140 cm/kyr for core 009 PC and 15-118 cm/kyr for core 004 PC, allowing for a millennial time scale resolution in each core. Our results indicate relatively harsh conditions in Lancaster Sound between 10,800 and 9000 cal BP (summer temperatures 2 °C cooler than at present), which we associate with the presence of active ice-streams in northernmost Baffin Bay and a weak West Greenland Current. This is followed by a warming trend (up to 3 °C higher than present) that took place between ˜8500 and 5500 cal BP, which we associate with the Holocene thermal maximum and to a large scale atmospheric pattern such as the Arctic Oscillation operating at the millennial time scale. This is concomitant with an increase in the relative abundance of phototrophic dinoflagellate cyst taxa. A gradual cooling of sea-surface temperature and increased sea-ice follow this from 5500 cal BP until the modern period. In Barrow Strait, harsh sea-surface conditions prevailed from 11,100 to 5500 cal BP, with summer temperatures as low as 4

  3. Climate Effects on Methylmercury Bioaccumulation Along a Latitudinal Gradient in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Chetelat, J.; Richardson, M.; MacMillan, G. A.; Amyot, M.; Hintelmann, H.; Crump, D.

    2014-12-01

    Recent evidence indicates that inorganic mercury (Hg) loadings to Arctic lakes decline with latitude. However, monomethylmercury (MMHg) concentrations in fish and their prey do not decline in a similar fashion, suggesting that higher latitude lakes are more vulnerable to Hg inputs. Preliminary results will be presented from a three-year study (2012-2015) of climate effects on MMHg bioaccumulation in lakes of the eastern Canadian Arctic. We have investigated mercury transport and accumulation processes in lakes and ponds from three study regions along a latitudinal gradient in climate-controlled ecosystem types in the Canadian Arctic, specifically sub-Arctic taiga, Arctic tundra and polar desert. In each water body, we measured key aspects of MMHg bioaccumulation—MMHg bioavailability to benthic food webs and organism growth rates—as well as how watershed characteristics affect the transport of Hg and organic carbon to lakes. Novel approaches were incorporated including the use of passive samplers (Diffusive Gradient in Thin Film samplers or DGTs) to estimate sediment bioavailable MMHg concentrations and tissue RNA content to compare organism short-term growth rates. A comparison of Arctic tundra and sub-Arctic taiga lakes showed that surface water concentrations of MMHg were strongly and positively correlated to total Hg concentrations both within and among study regions, implying strong control of inorganic Hg supply. Sediment concentrations of bioavailable MMHg were highly variable among lakes, although average concentrations were similar between study regions. Local environmental conditions appear to have a strong influence on sediment potential for MMHg supply. Lake-dwelling Arctic char from tundra lakes had similar or higher total Hg concentrations compared with brook trout from sub-Arctic lakes that were exposed to higher water MMHg concentrations. Potential environmental drivers of these patterns will be discussed. This latitudinal study will provide new

  4. Variation in peak growing season net ecosystem production across the Canadian Arctic.

    PubMed

    Lafleur, Peter M; Humphreys, Elyn R; St Louis, Vincent L; Myklebust, May C; Papakyriakou, Tim; Poissant, Laurier; Barker, Joel D; Pilote, Martin; Swystun, Kyle A

    2012-08-01

    Tundra ecosystems store vast amounts of soil organic carbon, which may be sensitive to climatic change. Net ecosystem production, NEP, is the net exchange of carbon dioxide (CO(2)) between landscapes and the atmosphere, and represents the balance between CO(2) uptake by photosynthesis and release by decomposition and autotrophic respiration. Here we examine CO(2) exchange across seven sites in the Canadian low and high Arctic during the peak growing season (July) in summer 2008. All sites were net sinks for atmospheric CO(2) (NEP ranged from 5 to 67 g C m(-2)), with low Arctic sites being substantially larger CO(2) sinks. The spatial difference in NEP between low and high Arctic sites was determined more by CO(2) uptake via gross ecosystem production than by CO(2) release via ecosystem respiration. Maximum gross ecosystem production at the low Arctic sites (average 8.6 μmol m(-2) s(-1)) was about 4 times larger than for high Arctic sites (average 2.4 μmol m(-2) s(-1)). NEP decreased with increasing temperature at all low Arctic sites, driven largely by the ecosystem respiration response. No consistent temperature response was found for the high Arctic sites. The results of this study clearly indicate there are large differences in tundra CO(2) exchange between high and low Arctic environments and this difference should be a central consideration in studies of Arctic carbon balance and climate change.

  5. Canadian Arctic Plate Reconstructions based on revised geological and geophysical data

    NASA Astrophysics Data System (ADS)

    Torsvik, Trond H.; Gaina, Carmen

    2015-04-01

    We present a revised rifting and seafloor spreading history around Greenland based on geological and geophysical constraints. Palaeomagnetic data from (i) Neoproterozoic dykes and sills in North America, NW Greenland, Devon and SW Ellesmere (Franklin and Clarence Head), (ii) Early Permian volcanism (Esayoo unit) in Ellesmere and (iii) Cretaceous volcanism and intrusive activity (Isachsen and Strandfjord Formations) in Axel Heiberg and Ellesmere have also been re-evaluated and used to develop a new Canadian Arctic plate model from Silurian to Paleogene times. We have tentatively divided the Canadian Arctic into seven tectonic units, including Pearya, which accreted to the northern sectors of Ellesmere and Axel Heiberg islands as part of the mid-Silurian Caledonide Orogeny. The Canadian Arctic was variable deformed during the Late Devonian Ellesmere and the Tertiary Eurekean events, the latter including c. 250 km of shortening and ultimately amalgamating all the Canadian Arctic units in the Late Eocene. Two of the units, Devon and SW Ellesmere must have been closely tied to NW Greenland (the 'Greenland Plate') in order to minimize Palaeocene-Eocene deformation across the Nares Strait during Labrador Sea and Baffin Bay seafloor spreading. We model 100 and 60 km of Late Cretaceous-Eocene transtension/extension in the Lancaster and Jones Sounds but in order to avoid too much continental overlap between Devon and North America (Lancaster Sound) we must include 150 km of pure strike-slip faulting along the Nares Strait.

  6. DBAE in an Arctic Fine Arts Program for Indigenous Canadian College Students.

    ERIC Educational Resources Information Center

    McNeal, Joanne

    1997-01-01

    Details the setting and context of a college-level fine arts program at Aurora College in the Canadian Arctic that drew adult students from several indigenous cultures. Offers an account of how Discipline-Based Art Education shaped the design of the program, and how it worked in the teaching and learning process. (DSK)

  7. Comparison of modelled and observed sea ice fluxes in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Huard, D. B.; Tremblay, B.; Lemieux, J.

    2009-12-01

    With the foreseeable increase in the strategic and economic importance of the Canadian Arctic Archipelago (CAA), a comprehensive picture of sea ice conditions at present and in the future is needed. However, due to the complex topography of the Canadian Arctic Archipelago (CAA), modelling sea ice fluxes in this area requires considerable spatial resolution. Our group has developed a stand-alone sea ice model based on the viscous-plastic rheology. The model includes both the Arctic Ocean and the CAA at a resolution of 10km, sufficient to resolve most of the channels and straits of the CAA. This study compares simulated fluxes across CAA channels and straits with satellite observations in order to identify potential improvements to the model and forcing fields. In particular, simulations were run with 32km resolution NARR surface winds instead of NCEP geostrophic winds in an attempt to capture wind channeling effects seen in the Eastern Arctic. Results show that fluxes are well simulated in the Western Arctic. In the Queen Elizabeth Islands region however, sea ice moves too freely compared with observations. The biggest challenge seems to be the Eastern Arctic, where the winter outflow of ice from Lancaster Sound towards Baffin Bay is not captured by the model. Potential explanations for the discrepancies are presented.

  8. Spatial and temporal trends of contaminants in terrestrial biota from the Canadian Arctic.

    PubMed

    Gamberg, Mary; Braune, Birgit; Davey, Eric; Elkin, Brett; Hoekstra, Paul F; Kennedy, David; Macdonald, Colin; Muir, Derek; Nirwal, Amar; Wayland, Mark; Zeeb, Barbara

    2005-12-01

    Contaminants in the Canadian Arctic have been studied over the last twelve years under the guidance of the Northern Contaminants Program. This paper summarizes results from that program from 1998 to 2003 with respect to terrestrial animals in the Canadian Arctic. The arctic terrestrial environment has few significant contaminant issues, particularly when compared with freshwater and marine environments. Both current and historical industrial activities in the north may have a continuing effect on biota in the immediate area, but effects tend to be localized. An investigation of arctic ground squirrels at a site in the Northwest Territories that had historically received applications of DDT concluded that DDT in arctic ground squirrels livers was the result of contamination and that this is an indication of the continuing effect of a local point source of DDT. Arsenic concentrations were higher in berries collected from areas around gold mines in the Northwest Territories than from control sites, suggesting that gold mining may significantly affect arsenic levels in berries in the Yellowknives Dene traditional territory. Although moose and caribou from the Canadian Arctic generally carry relatively low contaminant burdens, Yukon moose had high renal selenium concentrations, and moose and some woodland caribou from the same area had high renal cadmium levels, which may put some animals at risk of toxicological effects. Low hepatic copper levels in some caribou herds may indicate a shortage of copper for metabolic demands, particularly for females. Similarities in patterns of temporal fluctuations in renal element concentrations for moose and caribou suggest that environmental factors may be a major cause of fluctuations in renal concentrations of some elements. Concentrations of persistent organochlorines and metals in beaver and muskrat from the Northwest Territories, and carnivores from across the Canadian Arctic were very low and considered normal for terrestrial

  9. Compressor station for Arctic gas pipeline

    SciTech Connect

    Mast, B.T.

    1983-02-08

    By not using conventional refrigeration equipment, this process for cooling natural gas as it leaves the compressor requires less costly machinery, consumes less energy, reduces the frequency of mechanical failure, and takes full advantage of the ambient air in cooling the gas. The apparatus includes a gas-to-gas heat exchanger where the cold incoming gas is first preheated by the warm outgoing gas; this raises the initial temperature of the discharge gas to above the ambient temperature. The discharge gas is then cooled by the incoming gas and by the ambient air in a second heat exchanger. Finally, if further cooling is required, the system includes an expander for additional cooling. The design is particularly suited for use on Arctic pipelines to protect the permafrost from being melted by the warm gas.

  10. High Methylmercury in Arctic and Subarctic Ponds is Related to Nutrient Levels in the Warming Eastern Canadian Arctic.

    PubMed

    MacMillan, Gwyneth A; Girard, Catherine; Chételat, John; Laurion, Isabelle; Amyot, Marc

    2015-07-01

    Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L(-1)). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3-2.2 ng L(-1)) than polygonal ponds (0.1-0.3 ng L(-1)) or lakes (<0.1 ng L(-1)). High MeHg was measured in the bottom waters of Subarctic thaw ponds near Kuujjuarapik (0.1-3.1 ng L(-1)). High water MeHg concentrations in thaw ponds were strongly correlated with variables associated with high inputs of organic matter (DOC, a320, Fe), nutrients (TP, TN), and microbial activity (dissolved CO2 and CH4). Thawing permafrost due to Arctic warming will continue to release nutrients and organic carbon into these systems and increase ponding in some regions, likely stimulating higher water concentrations of MeHg. Greater hydrological connectivity from permafrost thawing may potentially increase transport of MeHg from thaw ponds to neighboring aquatic ecosystems. PMID:26030209

  11. Modern to millennium-old greenhouse gases emitted from freshwater ecosystems of the eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Bouchard, F.; Laurion, I.; Preskienis, V.; Fortier, D.; Xu, X.; Whiticar, M. J.

    2015-07-01

    Ponds and lakes are widespread across the rapidly changing permafrost environments. Aquatic systems play an important role in global biogeochemical cycles, especially in greenhouse gas (GHG) exchanges between terrestrial systems and the atmosphere. The source, speciation and emission of carbon released from permafrost landscapes are strongly influenced by local specific conditions rather than general environmental setting. This study reports on GHG ages and emission rates from aquatic systems on Bylot Island in the eastern Canadian Arctic. Dissolved and ebullition gas samples were collected during the summer season from different types of water bodies located in a highly dynamic periglacial valley: polygonal ponds, collapsed ice-wedge trough ponds, and larger lakes overlying unfrozen soils (talik). The results showed strikingly different ages and fluxes depending on aquatic system types. Polygonal ponds were net sinks of dissolved CO2, but variable sources of dissolved CH4. They presented the highest ebullition fluxes, one or two orders of magnitude higher than from other ponds and lakes. Trough ponds appeared as substantial GHG sources, especially when their edges were actively eroding. Both types of ponds produced modern to hundreds of years old (<550 yr BP) GHG, even if trough ponds could contain much older carbon (>2000 yr BP) derived from freshly eroded peat. Lakes had small dissolved and ebullition fluxes, however they released much older GHG, including millennium-old CH4 (up to 3500 yr BP) sampled from lake central areas. Acetoclastic methanogenesis dominated at all study sites and there was minimal, if any, methane oxidation in gas emitted through ebullition. These findings provide new insights on the variable role of permafrost aquatic systems as a positive feedback mechanism on climate.

  12. Preliminary assessment of geological applications of ERTS-1 imagery from selected areas of the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Gregory, A. F.

    1973-01-01

    An assessment of geological applications of ERTS-1 imagery from selected areas of the Canadian Arctic is presented. The three levels of interpretation which may be recognized and employed to derive information from a single image or data format are outlined. It is stated that one immediate benefit from ERTS will be improved efficiency in planning for and operation of programs of regional geological mapping. Imagery of various areas of Canada are presented to show applications to regional mapping.

  13. Implications of a Changing Arctic on Summertime Surface Seawater pCO2 Variations in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Burgers, T.; Miller, L. A.; Thomas, H.; Else, B. G. T.; Gosselin, M.; Papakyriakou, T. N.

    2015-12-01

    Arctic marine carbonate chemistry and rates of air-sea CO2 exchange are anticipated to be affected by current changes in sea-ice structure and extent, freshwater inputs, ocean circulation patterns, and the seasonality of phytoplankton blooms. This study examines how such changes will impact rates of air-sea CO2 exchange in northern Baffin Bay, Nares Strait, and the eastern Canadian Arctic Archipelago. This complex oceanographic region includes the North Water polynya; one of the most biologically productive areas in the Arctic Ocean, and the convergence site of the warm West Greenland Current with cold exported Arctic waters. Continuous measurements of atmospheric and surface seawater CO2 (pCO2) were collected onboard the Canadian Coast Guard Ship Amundsen during its 2013 and 2014 summer cruises. Surface seawater pCO2 displayed considerable variability (145 - 389 ppm), but never exceeded atmospheric concentrations. Calculated CO2 fluxes ranged from 0 to -45 mmol m-2 day-1 (oceanic uptake), and were estimated using the Sweeney et al. (2007) parameterization with in-situ wind speed measurements. Ancillary measurements of chlorophyll a reveal low productivity in surface waters during mid-summer with isolated sub-surface blooms. This is likely the result of nutrient limitation within the highly stratified polar mixed layer (PML). Measurements of stable oxygen isotope ratios (δ18O) and total alkalinity were used to estimate freshwater inputs (sea-ice melt vs. meteoric water) to the PML. These and in-situ observations of sea ice cover were used to interpret seawater pCO2 variations. Surface waters influenced by sea-ice melt exhibit lower pCO2 than those influenced by meteoric water. The results of this investigation shed light on the future role of this region as a summertime sink of atmospheric CO2.

  14. The effects of resolving the Canadian Arctic Archipelago in a finite element sea ice model

    NASA Astrophysics Data System (ADS)

    Lietaer, Olivier; Fichefet, Thierry; Legat, Vincent

    Though narrow straits may have a strong influence on the large-scale sea ice mass balance, they are often crudely represented in coarse resolution sea ice models. Unstructured meshes, with their natural ability to fit boundaries and locally increase the mesh resolution, propose an alternative framework to capture the complex oceanic areas formed by coasts and islands. In this paper, we develop a finite element sea ice model to investigate the sensitivity of the Arctic sea ice cover features to the resolution of the narrow straits constituting the Canadian Arctic Archipelago. The model is a two-level dynamic-thermodynamic sea ice model, including a viscous-plastic rheology. It is run over 1979-2005, forced by daily NCEP/NCAR reanalysis data. Confronting qualitatively numerical experiments with observations shows a good agreement with satellite and buoys measurements. Due to its simple representation of the oceanic interactions, the model overestimates the sea ice extent during winter in the southernmost parts of the Arctic, while the Baffin Bay and Kara Sea remain ice-covered during summer. In order to isolate the benefits from resolving the Canadian Arctic Archipelago, a numerical experiment is performed where we artificially close the archipelago. Focusing on the large-scale sea ice thickness pattern, no significant change is found in our model, except in the close surroundings of the archipelago. However, the local and short-term influences of the ice exchanges are nonnegligible. In particular, we show that the ice volume associated to the Canadian Arctic Archipelago represents 10% of the Northern Hemisphere sea ice volume and that the annual mean ice export towards Baffin Bay amounts to 125 km 3 yr -1, which may play an important role on the convective overturning in the Labrador Sea.

  15. Mercury and cadmium in ringed seals in the Canadian Arctic: Influence of location and diet.

    PubMed

    Brown, Tanya M; Fisk, Aaron T; Wang, Xiaowa; Ferguson, Steven H; Young, Brent G; Reimer, Ken J; Muir, Derek C G

    2016-03-01

    Concentrations of total mercury (THg) and total cadmium (TCd) were determined in muscle and liver of ringed seals (Pusa hispida) from up to 14 locations across the Canadian Arctic. Location, trophic position (TP) and relative carbon source best predicted the THg and TCd concentrations in ringed seals. THg concentrations in ringed seals were highest in the western Canadian Arctic (Beaufort Sea), whereas TCd was highest in the eastern Canadian Arctic (Hudson Bay and Labrador). A positive relationship between THg and TP and a negative relationship between THg and relative carbon source contributed to the geographical patterns observed and elevated THg levels at certain sites. In contrast, a negative relationship between TCd and TP was found, indicating that high TCd concentrations are related to seals feeding more on invertebrates than fish. Feeding ecology appears to play an important role in THg and TCd levels in ringed seals, with biomagnification driving elevated THg levels and a dependence on low-trophic position prey resulting in high TCd concentrations. The present study shows that both natural geological differences and diet variability among regions explain the spatial patterns for THg and TCd concentrations in ringed seals.

  16. Trace element concentrations and gastrointestinal parasites of Arctic terns breeding in the Canadian High Arctic.

    PubMed

    Provencher, J F; Braune, B M; Gilchrist, H G; Forbes, M R; Mallory, M L

    2014-04-01

    Baseline data on trace element concentrations are lacking for many species of Arctic marine birds. We measured essential and non-essential element concentrations in Arctic tern (Sterna paradisaea) liver tissue and brain tissue (mercury only) from Canada's High Arctic, and recorded the presence/absence of gastrointestinal parasites during four different phases of the breeding season. Arctic terns from northern Canada had similar trace element concentrations to other seabird species feeding at the same trophic level in the same region. Concentrations of bismuth, selenium, lead and mercury in Arctic terns were high compared to published threshold values for birds. Selenium and mercury concentrations were also higher in Arctic terns from northern Canada than bird species sampled in other Arctic areas. Selenium, mercury and arsenic concentrations varied across the time periods examined, suggesting potential regional differences in the exposure of biota to these elements. For unknown reasons, selenium concentrations were significantly higher in birds with gastrointestinal parasites as compared to those without parasites, while bismuth concentrations were higher in Arctic terns not infected with gastrointestinal parasites.

  17. Prevalence of Rabies Virus in Foxes Trapped in the Canadian Arctic

    PubMed Central

    Secord, D. C.; Bradley, J. A.; Eaton, R. D.; Mitchell, D.

    1980-01-01

    Brains and salivary glands of 521 trapped arctic foxes (Alopex lagopus) submitted from four different settlement areas in the Northwest Territories were examined for rabies by the standard fluorescent antibody and mouse inoculation tests. Rabies antigen was present in 44 of 201 (21.9%) brains from foxes trapped in the Sachs Harbour area, but submissions from Cambridge Bay (127), Spence Bay (93) and Gjoa Haven (100) were negative. Virus was also present in salivary glands from 43 (97.7%) of these 44 positive foxes. The arctic fox continues to be the main wildlife reservoir of rabies in the Canadian Arctic and foxes in the prodromal stage of the disease pose a particular threat to the trapper. Preexposure vaccination should always be a consideration in this occupational group. PMID:7459793

  18. Facies patterns and conodont biogeography in Arctic Alaska and the Canadian Arctic Islands: Evidence against juxtaposition of these areas during early Paleozoic time

    USGS Publications Warehouse

    Dumoulin, J.A.; Harris, A.G.; Bradley, D.C.; De Freitas, T. A.

    2000-01-01

    Differences in lithofacies and biofacies suggest that lower Paleozoic rocks now exposed in Arctic Alaska and the Canadian Arctic Islands did not form as part of a single depositional system. Lithologic contrasts are noted in shallow- and deep-water strata and are especially marked in Ordovician and Silurian rocks. A widespread intraplatform basin of Early and Middle Ordovician age in northern Alaska has no counterpart in the Canadian Arctic, and the regional drowning and backstepping of the Silurian shelf margin in Canada has no known parallel in northern Alaska. Lower Paleozoic basinal facies in northern Alaska are chiefly siliciclastic, whereas resedimented carbonates are volumetrically important in Canada. Micro- and macrofossil assemblages from northern Alaska contain elements typical of both Siberian and Laurentian biotic provinces; coeval Canadian Arctic assemblages contain Laurentian forms but lack Siberian species. Siberian affinities in northern Alaskan biotas persist from at least Middle Cambrian through Mississippian time and appear to decrease in intensity from present-day west to east. Our lithologic and biogeographic data are most compatible with the hypothesis that northern Alaska-Chukotka formed a discrete tectonic block situated between Siberia and Laurentia in early Paleozoic time. If Arctic Alaska was juxtaposed with the Canadian Arctic prior to opening of the Canada basin, biotic constraints suggest that such juxtaposition took place no earlier than late Paleozoic time.

  19. New evidence from the western Canadian Arctic Archipelago for the resubmergence of Bering Strait

    NASA Astrophysics Data System (ADS)

    England, John H.; Furze, Mark F. A.

    2008-07-01

    Widespread molluscan samples were collected from raised marine sediments to date the last retreat of the NW Laurentide Ice Sheet from the western Canadian Arctic Archipelago. At the head of Mercy Bay, northern Banks Island, deglacial mud at the modern coast contains Hiatella arctica and Portlandia arctica bivalves, as well as Cyrtodaria kurriana, previously unreported for this area. Multiple H. arctica and C. kurriana valves from this site yield a mean age of 11.5 14C ka BP (with 740 yr marine reservoir correction). The occurrence of C. kurriana, a low Arctic taxon, raises questions concerning its origin, because evidence is currently lacking for a molluscan refugium in the Arctic Ocean during the last glacial maximum. Elsewhere, the oldest late glacial age available on C. kurriana comes from the Laptev Sea where it is < 10.3 14C ka BP and attributed to a North Atlantic source. This is 2000 cal yr younger than the Mercy Bay samples reported here, making the Laptev Sea, ~ 3000 km to the west, an unlikely source. An alternate route from the North Atlantic into the Canadian Arctic Archipelago was precluded by coalescent Laurentide, Innuitian and Greenland ice east of Banks Island until ~ 10 14C ka BP. We conclude that the presence of C. kurriana on northern Banks Island records migration from the North Pacific. This requires the resubmergence of Bering Strait by 11.5 14C ka BP, extending previous age determinations on the reconnection of the Pacific and Arctic oceans by up to 1000 yr. This renewed ingress of Pacific water likely played an important role in re-establishing Arctic Ocean surface currents, including the evacuation of thick multi-year sea ice into the North Atlantic prior to the Younger Dryas geochron.

  20. Insights into aerosols, chemistry, and clouds from NETCARE: Observations from the Canadian Arctic in summer 2014

    NASA Astrophysics Data System (ADS)

    Abbatt, J.

    2015-12-01

    The Canadian Network on Aerosols and Climate: Addressing Key Uncertainties in Remote Canadian Regions (or NETCARE) was established in 2013 to study the interactions between aerosols, chemistry, clouds and climate. The network brings together Canadian academic and government researchers, along with key international collaborators. Attention is being given to observations and modeling of Arctic aerosol, with the goal to understand underlying processes and so improve predictions of aerosol climate forcing. Motivation to understand the summer Arctic atmosphere comes from the retreat of summer sea ice and associated increase in marine influence. To address these goals, a suite of measurements was conducted from two platforms in summer 2014 in the Canadian Arctic, i.e. an aircraft-based campaign on the Alfred Wegener Institute POLAR 6 and an ocean-based campaign from the CGCS Amundsen icebreaker. NETCARE-POLAR was based out of Resolute Bay, Nunavut during an initial period of little transport and cloud-free conditions and a later period characterized by more transport with potentially biomass burning influence. Measurements included particle and cloud droplet numbers and size distributions, aerosol composition, cloud nuclei, and levels of gaseous tracers. Ultrafine particle events were more frequently observed in the marine boundary layer than above, with particle growth observed in some cases to cloud condensation nucleus sizes. The influence of biological processes on atmospheric constituents was also assessed from the ship during NETCARE-AMUNDSEN, as indicated by high measured levels of gaseous ammonia, DMS and oxygenated VOCs, as well as isolated particle formation and growth episodes. The cruise took place in Baffin Bay and through the Canadian archipelago. Interpretation of the observations from both campaigns is enhanced through the use of chemical transport and particle dispersion models. This talk will provide an overview of NETCARE Arctic observational and

  1. Overview and regional and temporal differences of heavy metals in Arctic whales and ringed seals in the Canadian Arctic.

    PubMed

    Wagemann, R; Innes, S; Richard, P R

    1996-07-16

    Concentrations of mercury, cadmium, and other heavy metals in tissues of belugas (Delphinapterus leucas), narwhal (Monodon monoceros) and ringed seals (Phoca hispida) from across the Canadian Arctic are reported. Published and new information is used to provide an overview of metals in tissues of these animals, to delineate the existence of a spatial trend of mercury and cadmium in belugas and ringed seals, and to show a temporal trend is superimposed on the geochemical trend. Mercury concentrations in tissues of Arctic whales and ringed seals were high relative to the Canadian guideline of 0.5 micrograms/g wet wt., for mercury in fish, except in the skin of belugas (0.59-0.78 micrograms/g wet wt.) and flesh of ringed seals (0.39-0.41 micrograms/g wet wt.). In the flesh of belugas (0.94-1.34 micrograms/g wet wt.), and in the liver of ringed seals, tissues that are also consumed by Native people in the Arctic (8.34-27.5 micrograms/g wet wt.), the guideline value was significantly exceeded. Mean lead concentrations in tissues of belugas, narwhal and ringed seals were generally low (0.002-0.028 micrograms/g wet wt.), except in tissues of belugas in the St. Lawrence River (0.10-0.15 micrograms/g wet wt.). The concentration of zinc in the skin of whales was two to three times higher than in other tissues. The concentration of cadmium in organs was highest in narwhal. There was a positive correlation between mercury and selenium in the liver of all three species. The concentration of mercury in tissues of belugas and ringed seals was higher in the western than the eastern Arctic. This was attributed to different natural background concentrations in the western and eastern Arctic of Canada dictated by different geological formations in the two regions. Cadmium concentrations in tissues of belugas and ringed seals were higher in the eastern than the western Arctic. Zinc and copper in some tissues of belugas and ringed seals were also higher in the eastern than the western

  2. Parasites in grizzly bears from the central Canadian Arctic.

    PubMed

    Gau, R J; Kutz, S; Elkin, B T

    1999-07-01

    Standardized flotation techniques were used to survey 56 grizzly bear (Ursus arctos) fecal samples for parasites. The samples were collected during the spring and autumn of 1995 and 1996 in the central Arctic of the Northwest Territories (Canada). Parasites of the genera Nematodirus, gastrointestinal coccidia, and an unidentified first stage protostrongylid larva are reported for the first time from grizzly bear feces in North America. Parasites of the genera Diphyllobothrium and Baylisascaris also were collected. Prevalence of gastrointestinal parasites were significantly different between the spring and autumn seasons (31% and 58% respectively). Thus, we provide evidence supporting the theory that bears void gastrointestinal parasites before hibernation.

  3. An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife.

    PubMed

    Fisk, Aaron T; de Wit, Cynthia A; Wayland, Mark; Kuzyk, Zou Zou; Burgess, Neil; Letcher, Robert; Braune, Birgit; Norstrom, Ross; Blum, Susan Polischuk; Sandau, Courtney; Lie, Elisabeth; Larsen, Hans Jørgen S; Skaare, Janneche Utne; Muir, Derek C G

    2005-12-01

    Anthropogenic contaminants have been a concern in the Canadian arctic for over 30 years due to relatively high concentrations of bioaccumulating and biomagnifying organochlorine contaminants (OCs) and toxic metals found in some arctic biota and humans. However, few studies have addressed the potential effects of these contaminants in Canadian arctic wildlife. Prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects related to contaminant exposure, and compares new tissue concentration data to threshold effects levels. Weak relationships between cadmium, mercury and selenium burdens and health biomarkers in common eider ducks (Somateria mollissima borealis) in Nunavut were found but it was concluded that metals were not influencing the health of these birds. Black guillemots (Cepphus grylle) examined near PCB-contaminated Saglek Bay, Labrador, had enlarged livers, elevated EROD and liver lipid levels and reduced retinol (vitamin A) and retinyl palmitate levels, which correlated to PCB levels in the birds. Circulating levels of thyroid hormones in polar bears (Ursus maritimus) were correlated to PCB and HO-PCB plasma concentrations, but the impact at the population level is unknown. High PCB and organochlorine pesticide concentrations were found to be strongly associated with impaired humoral and cell-mediated immune responses in polar bears, implying an increased infection risk that could impact the population. In beluga whale (Delphinapterus leucas), cytochromes P450 (phase I) and conjugating (phase II) enzymes have been extensively profiled (immunochemically and catalytically) in liver, demonstrating the importance of contaminants in relation to enzyme induction, metabolism and potential contaminant bioactivation and fate. Concentrations of OCs and metals in arctic terrestrial wildlife, fish and seabirds are generally below effects thresholds

  4. An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife.

    PubMed

    Fisk, Aaron T; de Wit, Cynthia A; Wayland, Mark; Kuzyk, Zou Zou; Burgess, Neil; Letcher, Robert; Braune, Birgit; Norstrom, Ross; Blum, Susan Polischuk; Sandau, Courtney; Lie, Elisabeth; Larsen, Hans Jørgen S; Skaare, Janneche Utne; Muir, Derek C G

    2005-12-01

    Anthropogenic contaminants have been a concern in the Canadian arctic for over 30 years due to relatively high concentrations of bioaccumulating and biomagnifying organochlorine contaminants (OCs) and toxic metals found in some arctic biota and humans. However, few studies have addressed the potential effects of these contaminants in Canadian arctic wildlife. Prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects related to contaminant exposure, and compares new tissue concentration data to threshold effects levels. Weak relationships between cadmium, mercury and selenium burdens and health biomarkers in common eider ducks (Somateria mollissima borealis) in Nunavut were found but it was concluded that metals were not influencing the health of these birds. Black guillemots (Cepphus grylle) examined near PCB-contaminated Saglek Bay, Labrador, had enlarged livers, elevated EROD and liver lipid levels and reduced retinol (vitamin A) and retinyl palmitate levels, which correlated to PCB levels in the birds. Circulating levels of thyroid hormones in polar bears (Ursus maritimus) were correlated to PCB and HO-PCB plasma concentrations, but the impact at the population level is unknown. High PCB and organochlorine pesticide concentrations were found to be strongly associated with impaired humoral and cell-mediated immune responses in polar bears, implying an increased infection risk that could impact the population. In beluga whale (Delphinapterus leucas), cytochromes P450 (phase I) and conjugating (phase II) enzymes have been extensively profiled (immunochemically and catalytically) in liver, demonstrating the importance of contaminants in relation to enzyme induction, metabolism and potential contaminant bioactivation and fate. Concentrations of OCs and metals in arctic terrestrial wildlife, fish and seabirds are generally below effects thresholds

  5. Perfluorinated and polyfluorinated compounds in lake food webs from the Canadian high Arctic.

    PubMed

    Lescord, Gretchen L; Kidd, Karen A; De Silva, Amila O; Williamson, Mary; Spencer, Christine; Wang, Xiaowa; Muir, Derek C G

    2015-03-01

    Per- and polyfluorinated alkyl substances (PFASs) enter Arctic lakes through long-range atmospheric transport and local contamination, but their behavior in aquatic food webs at high latitudes is poorly understood. This study compared the concentrations of perfluorocarboxylates, perfluorosulfonates, and fluorotelomer sulfonates (FTS) in biotic and abiotic samples from six high Arctic lakes near Resolute Bay, Nunavut, Canada. Two of these lakes are known to be locally contaminated by a small airport and Arctic char (Salvelinus alpinus) from these lakes had over 100 times higher total [PFAS] when compared to fish from neighboring lakes. Perfluorononanoate (PFOA) and perfluorooctanesulfonate (PFOS) dominated in char, benthic chironomids (their main prey), and sediments, while pelagic zooplankton and water were dominated by lower chain acids and perfluorodecanesulfonate (PFDS). This study also provides the first measures of perfluoroethylcyclohexanesulfonate (PFECHS) and FTS compounds in water, sediment, juvenile char, and benthic invertebrates from lakes in the high Arctic. Negative relationships between [PFAS] and δ(15)N values (indicative of trophic position) within these food webs indicated no biomagnification. Overall, these results suggest that habitat use and local sources of contamination, but not trophic level, are important determinants of [PFAS] in biota from freshwater food webs in the Canadian Arctic.

  6. Volume and freshwater transports through the Canadian Arctic Archipelago-Baffin Bay system

    NASA Astrophysics Data System (ADS)

    Rudels, Bert

    2011-08-01

    Baffin Bay connects the Arctic Ocean and the Labrador Sea. It receives Polar water through the Canadian Arctic Archipelago and by the West Greenland Current. The Polar water is, after transformation, exported through Davis Strait. With control sections both upstream and downstream Baffin Bay invites the use of an idealized geostrophic approach to estimate transports. The baroclinic transports, driven by the density differences between the Arctic Ocean and Baffin Bay, are first determined. The density and upper layer depth are assumed the same in Lancaster Sound, Nares Strait and the West Greenland Current. Once the baroclinic transports are estimated the sea level difference between the Arctic Ocean and Baffin Bay is computed. Next the upper layer depth in Nares Strait and the West Greenland Current is reduced, while the sea level difference is kept constant. This allows for deep inflows through Nares Strait and the West Greenland Current. To establish a deep outflow through Davis Strait a "barotropic" sea level slope between the Arctic Ocean and the Labrador Sea is estimated from two "ideal" water columns. The transports are computed for different salinities in the Polar water and the salinity giving mass balance in the deeper layers is determined. The effects of possible increased melting of the Greenland icecap are examined. If the meltwater is added directly to Baffin Bay the effects are small, but if it is incorporated in the East and West Greenland Current a significant reduction of the outflow through the Archipelago might occur.

  7. Perfluorinated and polyfluorinated compounds in lake food webs from the Canadian high Arctic.

    PubMed

    Lescord, Gretchen L; Kidd, Karen A; De Silva, Amila O; Williamson, Mary; Spencer, Christine; Wang, Xiaowa; Muir, Derek C G

    2015-03-01

    Per- and polyfluorinated alkyl substances (PFASs) enter Arctic lakes through long-range atmospheric transport and local contamination, but their behavior in aquatic food webs at high latitudes is poorly understood. This study compared the concentrations of perfluorocarboxylates, perfluorosulfonates, and fluorotelomer sulfonates (FTS) in biotic and abiotic samples from six high Arctic lakes near Resolute Bay, Nunavut, Canada. Two of these lakes are known to be locally contaminated by a small airport and Arctic char (Salvelinus alpinus) from these lakes had over 100 times higher total [PFAS] when compared to fish from neighboring lakes. Perfluorononanoate (PFOA) and perfluorooctanesulfonate (PFOS) dominated in char, benthic chironomids (their main prey), and sediments, while pelagic zooplankton and water were dominated by lower chain acids and perfluorodecanesulfonate (PFDS). This study also provides the first measures of perfluoroethylcyclohexanesulfonate (PFECHS) and FTS compounds in water, sediment, juvenile char, and benthic invertebrates from lakes in the high Arctic. Negative relationships between [PFAS] and δ(15)N values (indicative of trophic position) within these food webs indicated no biomagnification. Overall, these results suggest that habitat use and local sources of contamination, but not trophic level, are important determinants of [PFAS] in biota from freshwater food webs in the Canadian Arctic. PMID:25604756

  8. Circumpolar oil-and-gas-bearing basins of the arctic part of the North American continent

    NASA Astrophysics Data System (ADS)

    Zabanbark, A.; Lobkovsky, L. I.

    2015-09-01

    Major geotectonic elements of the reviewed territory of the Arctic part of the North American continent are the Hyperborean Precambrian Platform, the Franklin folding belt, the northern part of the Precambrian Canadian platform, and the Mesozoic folding belt of Canada and Alaska. The rise of the Arctic slope of Alaska, the Beaufort Sea, and the Sverdrup basin are located in the southern margins of the Hyperborean Platform. The structure and peculiarities of development of these structural elements are genetically related to the evolution of this platform, as well as the current state of petroleum potential of the most promising exploration region of Arctic in the 21st century. The forced exploration of the Arctic regions of the United States and Canada has become an important milestone in the current development of the world energetics. Up to 100 oil, gas, and gas condensate fields have been discovered as a result of violent studies, and the potential oil and gas reserves in the Arctic part of the North American continent have been estimated to 30 billiion t and 50 trillion cubic meters, respectively. Many prospects are related to the continental slopes of all three above-mentioned basins; the total potential reserves of slopes are estimated as 10-12 billion t of oil and 20-25 trillion cubic meters of gas.

  9. Arctic Gas hydrate, Environment and Climate

    NASA Astrophysics Data System (ADS)

    Mienert, Jurgen; Andreassen, Karin; Bünz, Stefan; Carroll, JoLynn; Ferre, Benedicte; Knies, Jochen; Panieri, Giuliana; Rasmussen, Tine; Myhre, Cathrine Lund

    2015-04-01

    Arctic methane hydrate exists on land beneath permafrost regions and offshore in shelf and continental margins sediments. Methane or gas hydrate, an ice-like substrate, consists mainly of light hydrocarbons (mostly methane from biogenic sources but also ethane and propane from thermogenic sources) entrapped by a rigid cage of water molecules. The pressure created by the overlying water and sediments offshore stabilizes the CH4 in continental margins at a temperature range well above freezing point; consequently CH4 exists as methane ice beneath the seabed. Though the accurate volume of Arctic methane hydrate and thus the methane stored in hydrates throughout the Quaternary is still unknown it must be enormous if one considers the vast regions of Arctic continental shelves and margins as well as permafrost areas offshore and on land. Today's subseabed methane hydrate reservoirs are the remnants from the last ice age and remain elusive targets for both unconventional energy and as a natural methane emitter influencing ocean environments and ecosystems. It is still contentious at what rate Arctic warming may govern hydrate melting, and whether the methane ascending from the ocean floor through the hydrosphere reaches the atmosphere. As indicated by Greenland ice core records, the atmospheric methane concentration rose rapidly from ca. 500 ppb to ca. 750 ppb over a short time period of just 150 years at the termination of the younger Dryas period ca. 11600 years ago, but the dissociation of large quantities of methane hydrates on the ocean floor have not been documented yet (Brook et al., 2014 and references within). But with the major projected warming and sea ice melting trend (Knies et al., 2014) one may ask, for how long will CH4 stay trapped in methane hydrates if surface and deep-ocean water masses will warm and permafrost continuous to melt (Portnov et al. 2014). How much of the Arctic methane will be consumed by the micro- and macrofauna, how much will

  10. Natural gas production from Arctic gas hydrates

    SciTech Connect

    Collett, T.S. )

    1993-01-01

    The natural gas hydrates of the Messoyakha field in the West Siberian basin of Russia and those of the Prudhoe Bay-Kuparuk River area on the North Slope of Alaska occur within a similar series of interbedded Cretaceous and Tertiary sandstone and siltstone reservoirs. Geochemical analyses of gaseous well-cuttings and production gases suggest that these two hydrate accumulations contain a mixture of thermogenic methane migrated from a deep source and shallow, microbial methane that was either directly converted to gas hydrate or was first concentrated in existing traps and later converted to gas hydrate. Studies of well logs and seismic data have documented a large free-gas accumulation trapped stratigraphically downdip of the gas hydrates in the Prudhoe Bay-Kuparuk River area. The presence of a gas-hydrate/free-gas contact in the Prudhoe Bay-Kuparuk River area is analogous to that in the Messoyakha gas-hydrate/free-gas accumulation, from which approximately 5.17x10[sup 9] cubic meters (183 billion cubic feet) of gas have been produced from the hydrates alone. The apparent geologic similarities between these two accumulations suggest that the gas-hydrated-depressurization production method used in the Messoyakha field may have direct application in northern Alaska. 30 refs., 15 figs., 3 tabs.

  11. Decadal-Scale Increases in Dissolved Carbon Flux from the Western Canadian Arctic to the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tank, S. E.; Striegl, R. G.; McClelland, J. W.; Kokelj, S. V.

    2014-12-01

    The chemical signature of large rivers has a clear effect on the chemistry and biology of the nearshore ocean. At the same time, the flux of riverine constituents to coastal environments can be used to understand changes occurring over broad terrestrial landscapes. This is particularly relevant in the Arctic, where rivers have a disproportionate impact on nearshore ocean function. Additionally, change is playing out rapidly in Arctic regions, as permafrost thaw and changes in temperature and hydrology are exposing previously frozen soils, changing the nature of hydrological linkages between land and water, and affecting the seasonality of riverine chemistry and flux. Here, we examine a 40-year dataset of point-measurement alkalinity (largely dissolved inorganic carbon) and dissolved organic carbon (DOC) concentrations near the mouth of the Mackenzie River, in addition to similar data from four of the Mackenzie's major sub-catchments. These datasets are coupled with continuous discharge records, and capture flow from the fourth largest river discharging to the Arctic Ocean. Trends near the Mackenzie mouth show that annual fluxes of both alkalinity and DOC are increasing over time, with the proportional changes in DOC (approximately 16% per decade) being much greater than those for alkalinity (approximately 4% per decade). Seasonally, this increase in total flux occurs largely in the winter and late summer, for both constituents. Sub-catchment datasets indicate that these fluxes are increasing in northern, but not southern, sub-catchment regions. These results have clear implications for nearshore ocean function in the western Canadian Arctic. Increases in DOC may fuel increased bacterial metabolism, while differences in the magnitude of change in alkalinity and DOC flux may modify coastal aragonite saturation. Overall, the changing flux of dissolved carbon near the mouth of the Mackenzie River documents broad-scale changes in the carbon cycle of this region, both on

  12. The Pliocene High Arctic terrestrial palaeoenvironmental record and the development of the western Canadian Arctic coastal plain

    NASA Astrophysics Data System (ADS)

    Rybczynski, N.; Braschi, L.; Gosse, J. C.; Kennedy, C.; Fraser, D.; Lakeman, T.

    2013-12-01

    The Pliocene fossil record of the High Arctic is represented by a collection of sites that occur across the Canadian Arctic Archipelago (CAA), with deposits in the west comprising a 1200 km-long dissected clastic wedge (Beaufort Formation) and those in the east represented by high terrace gravel deposits. Fossil material from these sites is often very well preserved and provides evidence of a boreal-type forest. In the eastern Arctic our research sites includes the Fyles Leaf Bed (FLB) and the Beaver Pond (BP) sites, on west central Ellesmere Island. These are about 10 km apart and preserve evidence of forest and peatlands. The BP fossil site preserves the remains of fossil vertebrates including fish, frog, horse, beaver, deerlet, and black bear, consistent with a boreal type forest habitat. The FLB site has recently yielded the first fossil evidence for a High Arctic camel, identified with the help of collagen fingerprinting from a fragmentary limb bone (tibia). Although modern camels live in open habitats, biogeographic and comparative dental evidence, in combination, suggest that the North American Arctic camels were browsers, and therefore forest-dwelling. Paleoenvironmental reconstruction of the Ellesmere sites has yielded a Mean Annual Temperature of between 14 to 22 degrees Celsius warmer than today. Minimum cosmogenic nuclide burial ages of 3.4 and 3.8 Ma obtained for the BP and FLB sites, respectively, are consistent with vertebrate and floral biostratigraphic evidence. The Beaufort Formation, located in the Western CAA, was formed by a regional northwesterly flowing braided fluvial system. The Beaufort Formation appears to have filled at least the western portions of the 100 km-wide channels that currently separate the islands of the CAA. Intervals of Pliocene continental-shelf progradation are recorded in the lower Iperk Formation, which is situated offshore and includes complex sigmoid-oblique clinoforms indicative of high-energy, coarse

  13. The Endangered Arctic, the Arctic as Resource Frontier: Canadian News Media Narratives of Climate Change and the North.

    PubMed

    Stoddart, Mark C J; Smith, Jillian

    2016-08-01

    The Arctic is one of the most radically altered parts of the world due to climate change, with significant social and cultural impacts as a result. Using discourse network analysis and qualitative textual analysis of articles published in the Globe and Mail and National Post during the period 2006 to 2010, we identify and analyze key frames that interpret the implications of climate change on the Arctic. We examine Canadian national news media coverage to ask: How does the Arctic enter media coverage of climate change? Is there evidence of a climate justice discourse in relation to regional disparities in the risks and harms of climate change between northern and southern Canada? Climate change in the Arctic is often framed through the lens of Canadian national interests, which downplays climate-related social impacts that are already occurring at subnational political and geographical scales. L'Arctique est une des régions du monde la plus radicalement altérée par le changement climatique, menant comme résultat des importants changements sociaux et culturels. En utilisant l'analyse des réseaux de discours ainsi que l'analyse textuelle qualitative des articles publiés dans le Globe and Mail et le National Post de 2006 à 2010, nous identifions and analysons des cadres clés qui servent à interpréter les conséquences du changement climatique dans l'Arctique. Nous examinons la couverture des médias nationaux canadiens pour pouvoir demander : comment est-ce que l'Arctique s'insère dans la couverture médiatique du changement climatique? Est-ce qu'il y a de la preuve d'un discours de la justice climatique en relation des disparités régionales des risques et méfaits du changement climatique entre le Canada du nord et du sud? Le changement climatique dans l'Arctique est souvent encadré à travers le prisme des intérêts nationaux canadiens, ce qui minimise les impacts sociaux reliés au climat qui se produisent actuellement aux échelons sous

  14. The Endangered Arctic, the Arctic as Resource Frontier: Canadian News Media Narratives of Climate Change and the North.

    PubMed

    Stoddart, Mark C J; Smith, Jillian

    2016-08-01

    The Arctic is one of the most radically altered parts of the world due to climate change, with significant social and cultural impacts as a result. Using discourse network analysis and qualitative textual analysis of articles published in the Globe and Mail and National Post during the period 2006 to 2010, we identify and analyze key frames that interpret the implications of climate change on the Arctic. We examine Canadian national news media coverage to ask: How does the Arctic enter media coverage of climate change? Is there evidence of a climate justice discourse in relation to regional disparities in the risks and harms of climate change between northern and southern Canada? Climate change in the Arctic is often framed through the lens of Canadian national interests, which downplays climate-related social impacts that are already occurring at subnational political and geographical scales. L'Arctique est une des régions du monde la plus radicalement altérée par le changement climatique, menant comme résultat des importants changements sociaux et culturels. En utilisant l'analyse des réseaux de discours ainsi que l'analyse textuelle qualitative des articles publiés dans le Globe and Mail et le National Post de 2006 à 2010, nous identifions and analysons des cadres clés qui servent à interpréter les conséquences du changement climatique dans l'Arctique. Nous examinons la couverture des médias nationaux canadiens pour pouvoir demander : comment est-ce que l'Arctique s'insère dans la couverture médiatique du changement climatique? Est-ce qu'il y a de la preuve d'un discours de la justice climatique en relation des disparités régionales des risques et méfaits du changement climatique entre le Canada du nord et du sud? Le changement climatique dans l'Arctique est souvent encadré à travers le prisme des intérêts nationaux canadiens, ce qui minimise les impacts sociaux reliés au climat qui se produisent actuellement aux échelons sous

  15. Regional Modelling of Air Quality in the Canadian Arctic: Impact of marine shipping and North American wild fire emissions

    NASA Astrophysics Data System (ADS)

    Gong, W.; Beagley, S. R.; Zhang, J.; Cousineau, S.; Sassi, M.; Munoz-Alpizar, R.; Racine, J.; Menard, S.; Chen, J.

    2015-12-01

    Arctic atmospheric composition is strongly influenced by long-range transport from mid-latitudes as well as processes occurring in the Arctic locally. Using an on-line air quality prediction model GEM-MACH, simulations were carried out for the 2010 northern shipping season (April - October) over a regional Arctic domain. North American wildfire emissions and Arctic shipping emissions were represented, along with other anthropogenic and biogenic emissions. Sensitivity studies were carried out to investigate the principal sources and processes affecting air quality in the Canadian Northern and Arctic regions. In this paper, we present an analysis of sources, transport, and removal processes on the ambient concentrations and atmospheric loading of various pollutants with air quality and climate implications, such as, O3, NOx, SO2, CO, and aerosols (sulfate, black carbon, and organic carbon components). Preliminary results from a model simulation of a recent summertime Arctic field campaign will also be presented.

  16. Multiyear ice replenishment in the Canadian Arctic Archipelago: 1997-2013

    NASA Astrophysics Data System (ADS)

    Howell, Stephen E. L.; Derksen, Chris; Pizzolato, Larissa; Brady, Michael

    2015-03-01

    In the Canadian Arctic Archipelago (CAA), multiyear ice (MYI) replenishment from first-year ice aging (CAAMYI-Oct-1) and Arctic Ocean MYI exchange (CAAMYI-exchange) contribute to the CAA's relatively heavy sea ice conditions at the end of the summer melt season. We estimate these components using RADARSAT and the Canadian Ice Service Digital Archive and explore processes responsible for interannual variability from 1997 to 2013. CAAMYI-Oct-1 (52 ± 36 × 103 km2) provides a larger contribution than CAAMYI-exchange (13 ± 11 × 103 km2). CAAMYI-Oct-1 represents ˜10% of the amount that occurs in the Arctic Ocean. CAAMYI-exchange represents ˜50% of Nares Strait MYI export to Baffin Bay and ˜12% of Fram Strait MYI export to the Greenland Sea. CAAMYI-Oct-1 exhibits dependence on warmer (cooler) summers that increase (decrease) melt evident from strong relationships to surface air temperature (SAT), albedo and total absorbed solar radiation (Qtotal). CAAMYI-exchange is influenced by summer sea level pressure (SLP) anomalies over the Beaufort Sea and Canadian Basin which shifts the primary source of CAAMYI-exchange between less obstructed M'Clure Strait (low SLP anomalies) and the more obstructed Queen Elizabeth Islands (high SLP anomalies). Over the 17-record, appreciable replenishment occurred for most years from 1997 to 2004, reduced replenishment from 2005 to 2012, and large replenishment in 2013. The reduced replenishment period was associated with positive SAT, negative albedo, and positive Qtotal anomalies that facilitated more melt and less CAAMYI-Oct-1, together with high SLP anomalies that facilitated less CAAMYI-exchange. Large replenishment in 2013 was primarily from CAAMYI-Oct-1 attributed to strongly negative SAT and Qtotal anomalies and strongly positive albedo that impeded melt.

  17. Trophodynamics of some PFCs and BFRs in a western Canadian Arctic marine food web.

    PubMed

    Tomy, Gregg T; Pleskach, Kerri; Ferguson, Steve H; Hare, Jonathon; Stern, Gary; Macinnis, Gordia; Marvin, Chris H; Loseto, Lisa

    2009-06-01

    The trophodynamics of per- and polyfluorinated compounds and bromine-based flame retardants were examined in components of a marine food web from the western Canadian Arctic. The animals studied and their relative trophic status in the food web, established using stable isotopes of nitrogen (delta15N), were beluga (Delphinapterus leucas) > ringed seal (Phoca hispida) > Arctic cod (Boreogadus saida) > Pacific herring (Clupea pallasi) approximately equal to Arctic cisco (Coregonus autumnalis) > pelagic amphipod (Themisto libellula) > Arctic copepod (Calanus hyperboreus). For the brominated diphenyl ethers, the lipid adjusted concentrations of the seven congeners analyzed (Sigma7BDEs: -47, -85, -99, -100, -153, -154, and -209) ranged from 205.4 +/- 52.7 ng/g in Arctic cod to 2.6 +/- 0.4 ng/g in ringed seals. Mean Sigma7BDEs concentrations in Arctic copepods, 16.4 ng/g (n = 2, composite sample), were greater than those in the top trophic level (TL) marine mammals and suggests that (i) Arctic copepods are an important dietary component that delivers BDEs to the food web and (ii) because these compounds are bioaccumulative, metabolism and depletion of BDE congeners in top TL mammals is an important biological process. There were differences in the concentration profiles of the isomers of hexabromocyclododecane (HBCD) in the food web. The most notable difference was observed for beluga, where the alpha-isomer was enriched (accounting for approximately 90% of the SigmaHBCD body burden), relative to its primary prey species, Arctic cod, where the alpha-isomer accounted for only 20% of the SigmaHBCD body burden (beta: 4% and gamma: 78%). For the C8-C11 perfluorinated carboxylic acids, the trophic magnification factors (TMFs) were all greater than unity and increased with increasing carbon chain length. PFOS and its neutral precursor, PFOSA, also had TMF values greater than one. There were also pronounced differences in the PFOSA to PFOS ratio in ringed seal (0.04) and in

  18. Integrating terrestrial and marine archives of Late Wisconsinan ice stream dynamics in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Lakeman, Thomas; Blasco, Steve; MacLean, Brian; Bennett, Robbie; England, John; Hughes Clarke, John; Covill, Bob; Patton, Eric

    2014-05-01

    During Late Wisconsinan glaciation the northern Laurentide and Innuitian ice sheets converged over the Canadian Arctic Archipelago. This ice sheet complex included several major ice streams, which constituted important dynamical components. Discharging into the Beaufort Sea and Baffin Bay, these ice streams were a primary control on ice sheet mass balance and ice age sedimentation on adjacent continental margins, including the Arctic Ocean basin. This study presents a new compilation of multibeam echosounder data, sub-bottom profiler data, radiocarbon ages, and marine sediment cores acquired primarily during regional surveys with the CCGS Amundsen. These data characterize the nature and thickness of seafloor sediments in Parry Channel (and many of its connecting channels) and Amundsen Gulf. When combined with the results of terrestrial geomorphological mapping of the adjacent islands, this dataset constrains the maximum extent, chronology, and behaviour of former ice streams in M'Clure Strait, Viscount Melville Sound, Lancaster Sound, and Amundsen Gulf. Importantly, these data highlight complex patterns of past ice stream flow during regional deglaciation. These results contribute to a better understanding of the causal mechanisms that occasioned retreat of the terrestrial and marine sectors of the Laurentide and Innuitian ice sheets. As well, this study helps to quantify past iceberg fluxes to the Arctic Ocean, which has implications for assessing past climate, and the origin of ice-rafted sediment and deep iceberg scours in the Arctic Ocean basin.

  19. The effect of snow cover on lemming population cycles in the Canadian high Arctic.

    PubMed

    Bilodeau, Frédéric; Gauthier, Gilles; Berteaux, Dominique

    2013-08-01

    Rising temperatures and changes in the precipitation regime will have a strong impact on the quality of the snow cover in the Arctic. A snow cover of good quality protecting lemmings from cold temperatures and predators is thought to be an important factor for maintaining the cyclic dynamic of their populations in the tundra. We examined if the characteristics of annual fluctuations (amplitude and shape of phases) in brown lemming (Lemmus trimucronatus) density could be determined by snow depth, snow density, sub-nivean temperature and persistence of snow. Using an 18-year time series of brown lemming abundance on Bylot Island in the Canadian Arctic, we tested if snow variables could explain the residual variation between the observed lemming density and the one predicted by models where cyclicity had been accounted for. Our analysis provides support for the hypothesis that snow cover can affect the amplitude and possibly also the periodicity of lemming population cycles in the High Arctic. Summer abundance of brown lemmings was higher following winters with a deep snow cover and a low-density snow pack near the ground but was unaffected by the date of establishment or melting and duration of the snow cover. Two snow variables showed a temporal trend; mean winter snow depth tended to increase and date of establishment of the hiemal threshold occurred earlier over time. These temporal trends, which should be favourable to lemmings, may explain why healthy population cycles have apparently been maintained at our study site contrary to other Arctic sites.

  20. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    NASA Astrophysics Data System (ADS)

    Laurion, Isabelle; Mladenov, Natalie

    2013-09-01

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d-1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d-1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO2) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen.

  1. Otitis media in Inuit children in the Eastern Canadian Arctic--an overview--1968 to date.

    PubMed

    Baxter, J D

    1999-10-01

    Clinical observations made on the Inuit in the Eastern Canadian Arctic during the past three decades support that the current high prevalence of chronic otitis media among their children is a relatively new phenomenon. It is a social/economic disease related to their urbanization that occurred following World War II when the vast majority of the Inuit abandoned their isolated nomadic way of life and moved into permanent settlements. The disease, in a great many, runs a natural course with spontaneous healing. There is evidence that as the new millennium approaches the prevalence of the disease among the children is decreasing.

  2. The Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Project: Overview and results from ten years of ACE operations

    NASA Astrophysics Data System (ADS)

    Walker, Kaley; Strong, Kimberly

    2014-05-01

    As of February 2014, the Canadian-led Atmospheric Chemistry Experiment (ACE) satellite mission has been making measurements of the Earth's atmosphere for ten years. As ACE operations have extended beyond the initial two-year mission, there is a continuing need to validate the trace gas data products from the ACE-Fourier Transform Spectrometer (ACE-FTS) and the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (ACE-MAESTRO) instruments. Ground-based measurements provide critical data for the validation of satellite retrievals of trace gases and for the assessment of long-term stability of these measurements. In particular, validation comparisons are needed for ACE during Arctic springtime to understand better the measurements of species involved in stratospheric ozone chemistry. To this end, eleven Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Campaigns have been conducted during the spring period (February - April in 2004 - 2014) at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut (80°N, 86°W). This period coincides with the most chemically active time of year in the Arctic, as well as a significant number of satellite overpasses. A suite of as many as 12 ground-based instruments, as well as frequent balloon-borne ozonesonde and radiosonde launches, have been used in each campaign. These instruments include: a ground-based version of the ACE-FTS (PARIS - Portable Atmospheric Research Interferometric Spectrometer), a terrestrial version of the ACE-MAESTRO, a SunPhotoSpectrometer, two zenith-viewing UV-visible grating spectrometers, a Bomem DA8 Fourier transform spectrometer, a Bruker 125HR Fourier transform spectrometer, a Systeme d'Analyse par Observations Zenithales (SAOZ) instrument, and several Brewer spectrophotometers. In the past several years, these results have been used to validate the measurements by the ACE-FTS and ACE-MAESTRO instruments on SCISAT as well

  3. Recent changes in the multi-year ice area budget of the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Howell, Stephen; Pizzolato, Larissa; Derksen, Chris; Brady, Michael

    2014-05-01

    The Canadian Arctic Archipelago (CAA) is intricate collection of islands and channels located on the North American continental shelf. The deep-water route of the North West Passage crosses through the CAA near 75°N connecting the Atlantic and Pacific Oceans. The major challenge to safe navigation of the North West Passage is the presence of multi-year sea ice (MYI). In recent years, MYI conditions within the CAA during September have begun to decrease considerably with 2011 and 2012 being the lightest MYI years on record since 1968. Recent light MYI years within the CAA are associated with recent openings of the North West Passage (i.e. 2007, 2008, 2010, 2011 and 2012). MYI within the CAA is either imported from the Arctic Ocean or grown in situ and therefore in order to understand the processes contributing to these recent reductions in September MYI within the CAA we derived the first estimates of the MYI area budget of the CAA using RADARSAT-1 and RADARSAT-2 imagery from 1997-2012. Overall, there has been a reduced amount of Arctic Ocean MYI inflow into the CAA during the summer months since 2007. The latter process can be attributed to more frequent high sea level pressure anomalies over the Beaufort Sea and Canadian Basin. The amount of MYI grown in situ within the CAA has also reduced because of longer melt seasons reducing the survivability of seasonal ice over. MYI outflow to Baffin Bay from the CAA has been relatively consistent over the period. Interestingly, the recent reduced amount of MYI within the CAA, particularly noticeable since 2007, was found to be quantitatively linked with a step change increase in observed Arctic marine shipping activity following the dramatic summer sea ice reductions that began in 2007.

  4. Spatial and temporal trends of contaminants in Canadian Arctic freshwater and terrestrial ecosystems: a review.

    PubMed

    Braune, B; Muir, D; DeMarch, B; Gamberg, M; Poole, K; Currie, R; Dodd, M; Duschenko, W; Eamer, J; Elkin, B; Evans, M; Grundy, S; Hebert, C; Johnstone, R; Kidd, K; Koenig, B; Lockhart, L; Marshall, H; Reimer, K; Sanderson, J; Shutt, L

    1999-06-01

    The state of knowledge of contaminants in Canadian Arctic biota of the freshwater and terrestrial ecosystems has advanced enormously since the publication of the first major reviews by Lockhart et al. and Thomas et al. in The Science of the Total Environment in 1992. The most significant gains are new knowledge of spatial trends of organochlorines and heavy metal contaminants in terrestrial animals, such as caribou and mink, and in waterfowl, where no information was previously available. Spatial trends in freshwater fish have been broadened, especially in the Yukon, where contaminant measurements of, for example, organochlorines were previously non-existent. A review of contaminants data for fish from the Northwest Territories, Yukon and northern Quebec showed mercury as the one contaminant which consistently exceeds guideline limits for subsistence consumption or commercial sale. Lake trout and northern pike in the Canadian Shield lakes of the Northwest Territories and northern Quebec generally had the most elevated levels. Levels of other heavy metals were generally not elevated in fish. Toxaphene was the major organochlorine contaminant in all fish analyzed. The concentrations of organochlorine contaminants in fish appear to be a function not only of trophic level but of other aspects of the lake ecosystem. Among Arctic terrestrial mammals, PCBs and cadmium were the most prominent contaminants in the species analyzed. Relatively high levels (10-60 micrograms g-1) of cadmium were observed in kidney and liver of caribou from the Yukon, the Northwest Territories and northern Quebec, with concentrations in western herds being higher than in those from the east. For the organochlorine contaminants, a west to east increase in zigma PCBs, HCB and zigma HCH was found in caribou, probably as a result of the predominant west to east/north-east atmospheric circulation pattern which delivers these contaminants from industrialized regions of central and eastern North

  5. Spatial and temporal trends of contaminants in Canadian Arctic freshwater and terrestrial ecosystems: a review.

    PubMed

    Braune, B; Muir, D; DeMarch, B; Gamberg, M; Poole, K; Currie, R; Dodd, M; Duschenko, W; Eamer, J; Elkin, B; Evans, M; Grundy, S; Hebert, C; Johnstone, R; Kidd, K; Koenig, B; Lockhart, L; Marshall, H; Reimer, K; Sanderson, J; Shutt, L

    1999-06-01

    The state of knowledge of contaminants in Canadian Arctic biota of the freshwater and terrestrial ecosystems has advanced enormously since the publication of the first major reviews by Lockhart et al. and Thomas et al. in The Science of the Total Environment in 1992. The most significant gains are new knowledge of spatial trends of organochlorines and heavy metal contaminants in terrestrial animals, such as caribou and mink, and in waterfowl, where no information was previously available. Spatial trends in freshwater fish have been broadened, especially in the Yukon, where contaminant measurements of, for example, organochlorines were previously non-existent. A review of contaminants data for fish from the Northwest Territories, Yukon and northern Quebec showed mercury as the one contaminant which consistently exceeds guideline limits for subsistence consumption or commercial sale. Lake trout and northern pike in the Canadian Shield lakes of the Northwest Territories and northern Quebec generally had the most elevated levels. Levels of other heavy metals were generally not elevated in fish. Toxaphene was the major organochlorine contaminant in all fish analyzed. The concentrations of organochlorine contaminants in fish appear to be a function not only of trophic level but of other aspects of the lake ecosystem. Among Arctic terrestrial mammals, PCBs and cadmium were the most prominent contaminants in the species analyzed. Relatively high levels (10-60 micrograms g-1) of cadmium were observed in kidney and liver of caribou from the Yukon, the Northwest Territories and northern Quebec, with concentrations in western herds being higher than in those from the east. For the organochlorine contaminants, a west to east increase in zigma PCBs, HCB and zigma HCH was found in caribou, probably as a result of the predominant west to east/north-east atmospheric circulation pattern which delivers these contaminants from industrialized regions of central and eastern North

  6. Overview of analogue science activities at the McGill Arctic Research Station, Axel Heiberg Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Pollard, Wayne; Haltigin, Tim; Whyte, Lyle; Niederberger, Thomas; Andersen, Dale; Omelon, Christopher; Nadeau, Jay; Ecclestone, Miles; Lebeuf, Martin

    2009-05-01

    The Canadian High Arctic contains several of the highest fidelity Mars analogue sites in the world. Situated at nearly 80° north, Expedition Fjord on Axel Heiberg Island is located within a polar desert climate, with the surrounding landscape and conditions providing an invaluable opportunity to examine terrestrial processes in a cold, dry environment. Through the Canadian Space Agency's Analogue Research Network program, scientific activities based out of the McGill Arctic Research Station (M.A.R.S.) are extremely broad in scope, representing physical, biological, and technological investigations. Some of the most unique hydrogeologic features under investigation near M.A.R.S. are a series of cold saline springs that maintain liquid-state flow year round regardless of air temperature. Previous studies have examined their geomorphic relation to discharge-related formations, water chemistry, temperature monitoring, discharge rates, and combined flow/thermal modeling. Recent investigations have identified microbial communities and characterized biological activity within the springs and within permafrost sections, having direct relevance to astrobiological analogue research goals. Another main thrust of research activities based at M.A.R.S. pertains to the detection, mapping, and quantification of subsurface ice deposits. A long-term study is presently underway examining polygonal terrain, comparing surficial patterns found in the region with those identified on Mars, and using surface morphology to estimate ice wedge volumes through a combination of aerial photography interpretation and ground-based geophysical techniques. Other technological developments include the use of in situ microscopy for the detection of biomarkers and improved permafrost drilling techniques. This paper presents an overview of previous studies undertaken at M.A.R.S. over the past decades and will describe in detail both present and upcoming work.

  7. Is Submarine Groundwater Discharge a Gas Hydrate Formation Mechanism on the Circum-Arctic Shelf?

    NASA Astrophysics Data System (ADS)

    Frederick, J. M.; Buffett, B. A.

    2015-12-01

    Methane hydrate is an ice-like solid that can sequester large quantities of methane gas in marine sediments along most continental margins where thermodynamic conditions permit its formation. Along the circum-Arctic shelf, relict permafrost-associated methane hydrate deposits formed when non-glaciated portions of the shelf experienced subaerial exposure during ocean transgressions. Gas hydrate stability and the permeability of circum-Arctic shelf sediments to gas migration is closely linked with relict submarine permafrost. Heat flow observations on the Alaskan North Slope and Canadian Beaufort Shelf suggest the movement of groundwater offshore, but direct observations of groundwater flow do not exist. Submarine discharge, an offshore flow of fresh, terrestrial groundwater, can affect the temperature and salinity field in shelf sediments, and may be an important factor in submarine permafrost and gas hydrate evolution on the Arctic continental shelf. Submarine groundwater discharge may also enhance the transport of organic matter for methanogenesis within marine sediments. Because it is buoyancy-driven, the velocity field contains regions with a vertical (upward) component as groundwater flows offshore. This combination of factors makes submarine groundwater discharge a potential mechanism controlling permafrost-associated gas hydrate evolution on the Arctic continental shelf. In this study, we quantitatively investigate the feasibility of submarine groundwater discharge as a control on permafrost-associated gas hydrate formation on the Arctic continental shelf, using the Canadian Beaufort Shelf as an example. We have developed a shelf-scale, two-dimensional numerical model based on the finite volume method for two-phase flow of pore fluid and methane gas within Arctic shelf sediments. The model tracks the evolution of the pressure, temperature, salinity, methane gas, methane hydrate, and permafrost fields given imposed boundary conditions, with latent heat of

  8. Transport Regimes of Air Masses Affecting the Tropospheric Composition of the Canadian and European Arctic During RACEPAC 2014 and NETCARE 2014/2015

    NASA Astrophysics Data System (ADS)

    Bozem, H.; Hoor, P. M.; Koellner, F.; Kunkel, D.; Schneider, J.; Schulz, C.; Herber, A. B.; Borrmann, S.; Wendisch, M.; Ehrlich, A.; Leaitch, W. R.; Willis, M. D.; Burkart, J.; Thomas, J. L.; Abbatt, J.

    2015-12-01

    The Arctic is warming much faster than any other place in the world and undergoes a rapid change dominated by a changing climate in this region. The impact of polluted air masses traveling to the Arctic from various remote sources significantly contributes to the observed climate change, in contrast there are additional local emission sources contributing to the level of pollutants (trace gases and aerosol). Processes affecting the emission and transport of these pollutants are not well understood and need to be further investigated. We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories we analyze the transport regimes prevalent during spring (RACEPAC 2014 and NETCARE 2015) and summer (NETCARE 2014) in the observed region. Whereas the eastern part of the Canadian Arctic is affected by air masses with their origin in Asia, in the central and western parts of the Canadian and European Arctic air masses from North America are predominant at the time of the measurement. In general the more northern parts of the Arctic were relatively unaffected by pollution from mid-latitudes since air masses mostly travel within the polar dome, being quite isolated. Associated mixing ratios of CO and CO2 fit into the seasonal cycle observed at NOAA ground stations throughout the Arctic, but show a more mid-latitudinal characteristic at higher altitudes. The transition is remarkably sharp and allows for a chemical definition of the polar dome. At low altitudes, synoptic disturbances transport polluted air masses from mid-latitudes into regions of the polar dome. These air masses contribute to the Arctic pollution background, but also

  9. Cretaceous magmatism in the High Canadian Arctic: Implications for the nature and age of Alpha Ridge

    NASA Astrophysics Data System (ADS)

    Bono, Richard; Tarduno, John; Singer, Brad

    2013-04-01

    Cretaceous magmatism in the High Arctic, best expressed on Axel Heiberg and Ellesmere Island, can provide clues to the nature and age of the adjacent Alpha Ridge, which is in turn a key to understanding the tectonic evolution of the Arctic Ocean. Although the incorporation of some continental crust cannot be excluded, the prevailing view is that Alpha Ridge is dominantly thickened oceanic crust, analogous to oceanic plateaus of the Pacific and Indian Ocean. Together with the on-land volcanic exposures, Alpha Ridge composes the High Arctic Large Igneous Province (LIP), but the physical processes responsible for the magmatism remain unclear. Here we focus on two volcanic formations found on the Canadian Arctic margin. The Strand Fiord Formation is composed of a series of classic continental flood basalt flows, and represents the most voluminous expression of volcanism that has survived erosion. These basalts yield a 40Ar/39Ar age of ~95 Ma (Tarduno et al., Science, 1998) but this comes from the distant edge of the flood basalt exposures. The Hansen Point Volcanics consist of felsic and mafic rocks; previous age assignments range from the Maastrichtian (on the basis of palynomorphs, Falcon-Lang et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2004) to 80 Ma (Rb/Sr isochron, Estrada and Henjes-Kunst, Z. dt. Geol. Ges, 2004). Here we report new 40Ar/39Ar radioisotopic and paleomagnetic data from the Hansen Point Volcanics. In contrast to the latest Cretaceous/Paleogene dates, we find ages of ~95 Ma and 88-90 Ma. Because of the proximity of the landward extension of Alpha Ridge to Hansen Point, these new ages suggest that volcanism that contributed to the construction of Alpha Ridge may have extended over at least a 7 million interval (although it could have occurred in pulses). We will discuss the implications of these new data for candidate mantle processes that could have been responsible for the emplacement of Alpha Ridge and the High Arctic LIP.

  10. Unexpectedly high radioactivity burdens in ice-rafted sediments from the Canadian Arctic Archipelago.

    PubMed

    Cota, Glenn F; Cooper, Lee W; Darby, Dennis A; Larsen, I L

    2006-07-31

    Unexpectedly high specific activities of (137)Cs (1800-2000 Bq kg(-1) dry weight) have been detected in fine-grained sediments entrained in multi-year sea ice floes grounded in Resolute Bay near the center of the Northwest Passage through the Canadian Arctic Archipelago. These results are remarkable because: (1) the specific activities are about two orders of magnitude higher than average specific activities detected in previous studies of sea ice rafted sediments from the Arctic Ocean, (2) two independent observations of these unexpectedly high specific activities were made several years apart, (3) the sampling site is on the opposite side of the Arctic basin from potential radioactive sources such as disposal and weapons testing sites of the former Soviet Union and nuclear fuel reprocessing sites in western Europe, and (4) the closest compositional match to known geologic source regions is Banks Island, on the western edge of the Arctic Archipelago, although a smaller number of grains from one of the two samples were mineralogically matched to sediments in the Laptev Sea. Consequently, the sediments are probably not from a single distinct source and were likely mixed during sea ice transport. Coupled with previous observations of higher radionuclide specific activities in some sea ice rafted sediments relative to bottom sediments, these new observations indicate that comparatively high as well as variable radioactive contaminant burdens in ice rafted sediments must be common and geographically independent of proximity to known contaminant sources. The mechanisms that would facilitate these unexpected high radionuclide burdens in sea ice are not known and require additional study, as well as investigations of the implications for the transport and fate of contaminants in Arctic sea ice. PMID:16197983

  11. Unexpectedly high radioactivity burdens in ice-rafted sediments from the Canadian Arctic Archipelago.

    PubMed

    Cota, Glenn F; Cooper, Lee W; Darby, Dennis A; Larsen, I L

    2006-07-31

    Unexpectedly high specific activities of (137)Cs (1800-2000 Bq kg(-1) dry weight) have been detected in fine-grained sediments entrained in multi-year sea ice floes grounded in Resolute Bay near the center of the Northwest Passage through the Canadian Arctic Archipelago. These results are remarkable because: (1) the specific activities are about two orders of magnitude higher than average specific activities detected in previous studies of sea ice rafted sediments from the Arctic Ocean, (2) two independent observations of these unexpectedly high specific activities were made several years apart, (3) the sampling site is on the opposite side of the Arctic basin from potential radioactive sources such as disposal and weapons testing sites of the former Soviet Union and nuclear fuel reprocessing sites in western Europe, and (4) the closest compositional match to known geologic source regions is Banks Island, on the western edge of the Arctic Archipelago, although a smaller number of grains from one of the two samples were mineralogically matched to sediments in the Laptev Sea. Consequently, the sediments are probably not from a single distinct source and were likely mixed during sea ice transport. Coupled with previous observations of higher radionuclide specific activities in some sea ice rafted sediments relative to bottom sediments, these new observations indicate that comparatively high as well as variable radioactive contaminant burdens in ice rafted sediments must be common and geographically independent of proximity to known contaminant sources. The mechanisms that would facilitate these unexpected high radionuclide burdens in sea ice are not known and require additional study, as well as investigations of the implications for the transport and fate of contaminants in Arctic sea ice.

  12. Postglacial environmental succession of Nettilling Lake (Baffin Island, Canadian Arctic) inferred from biogeochemical and microfossil proxies

    NASA Astrophysics Data System (ADS)

    Narancic, Biljana; Pienitz, Reinhard; Chapligin, Bernhard; Meyer, Hanno; Francus, Pierre; Guilbault, Jean-Pierre

    2016-09-01

    Nettilling Lake (Baffin Island, Nunavut) is currently the largest lake in the Canadian Arctic Archipelago. Despite its enormous size, this freshwater system remains little studied until the present-day. Existing records from southern Baffin Island indicate that in the early postglacial period, the region was submerged by the postglacial Tyrell Sea due to isostatic depression previously exerted by the Laurentide Ice Sheet. However, these records are temporally and spatially discontinuous, relying on qualitative extrapolation. This paper presents the first quantitative reconstruction of the postglacial environmental succession of the Nettilling Lake basin based on a 8300 yr-long high resolution sedimentary record. Our multi-proxy investigation of the glacio-isostatic uplift and subsequent changes in paleosalinity and sediment sources is based on analyses of sediment fabric, elemental geochemistry (μ-XRF), diatom assemblage composition, as well as on the first diatom-based oxygen isotope record from the eastern Canadian Arctic. Results indicate that the Nettilling Lake basin experienced a relatively rapid and uniform marine invasion in the early Holocene, followed by progressive freshening until about 6000 yr BP when limnological conditions similar to those of today were established. Our findings present evidence for deglacial processes in the Foxe Basin that were initiated at least 400yrs earlier than previously thought.

  13. Expanding Canadian natural gas production will strengthen growth of LP-gas industry

    SciTech Connect

    Hawkins, D.J. )

    1994-01-01

    In 1992, over 86% of Canadian propane and 70% of Canadian butane production originated in gas plants. Propane and butane production not recovered at gas plants is recovered in other processing facilities, primarily refineries and heavy oil upgraders. As a result, supplies of both products are largely tied to natural gas production, and the outlook for natural gas therefore provides the basis for any discussion on the outlook for gas processing and NGL industry infrastructure. The paper discusses gas processing, economies of scale, NGL supply, expected declines, industry structure and infrastructure, the two major centers of the Canadian NGL industry, new shippers, and required pipeline expansion.

  14. The contribution of Alaskan, Siberian, and Canadian coastal polynas to the cold halocline layer of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Martin, Seelye

    1994-01-01

    Numerous Arctic Ocean circulation and geochemical studies suggest that ice growth in polynyas over the Alaskan, Siberian, and Canadian continental shelves is a source of cold, saline water which contributes to the maintenance of the Arctic Ocean halocline. The purpose of this study is to estimate for the 1978-1987 winters the contributions of Arctic coastal polynyas to the cold halocline layer of the Arctic Ocean. The study uses a combination of satellite, oceanographic, and weather data to calculate the brine fluxes from the polynyas; then an oceanic box model is used to calculate their contributions to the cold halocline layer of the Arctic Ocean. This study complements and corrects a previous study of dense water production by coastal polynyas in the Barents, Kara, and Laptev Seas.

  15. The current distribution and thermal stability of natural gas hydrates in the Canadian polar regions

    SciTech Connect

    Judge, A.; Smith, S.L.; Majorowicz, J.

    1994-12-31

    Natural gas hydrates may contribute to both future energy supplies and to the increase of atmospheric greenhouse gases. Evaluation of the importance of gas hydrates requires an improved knowledge of the present hydrate distribution. Analysis of thermal and geophysical logs from 369 wells in the Canadian Arctic Islands and the Beaufort Sea-Mackenzie Delta regions indicates that a maximum of 1,900 to 3,900 Gt of methane may be stored as hydrate in this region. Consideration of the recent geological and climatic history of the area demonstrates that the volume of hydrate is variable with time. Decomposition of hydrates is possibly occurring beneath approximately 73,000 km{sup 2} of the Canadian Beaufort Shelf. Approximately 10{sup 5} m{sup 3} hydrate/km{sup 2} may become unstable over a 100 year period due to marine transgression. In contrast, cooling of sediments and hydrate formation is occurring in the Arctic Islands as new land emerges from the ocean in response to isostatic rebound.

  16. Summertime sources of dimethyl sulfide in the Canadian Arctic Archipelago and Baffin Bay

    NASA Astrophysics Data System (ADS)

    Mungall, E. L.; Croft, B.; Lizotte, M.; Thomas, J. L.; Murphy, J. G.; Levasseur, M.; Martin, R. V.; Wentzell, J. J. B.; Liggio, J.; Abbatt, J. P. D.

    2015-12-01

    Dimethyl sulfide (DMS) plays a major role in the global sulfur cycle. In addition, its atmospheric oxidation products contribute to the formation and growth of atmospheric aerosol particles, thereby influencing cloud condensation nuclei (CCN) populations and thus cloud formation. The pristine summertime Arctic atmosphere is a CCN-limited regime, and is thus very susceptible to the influence of DMS. However, atmospheric DMS mixing ratios have only rarely been measured in the summertime Arctic. During July-August 2014, we conducted the first high time resolution (10 Hz) DMS mixing ratio measurements for the Eastern Canadian Archipelago and Baffin Bay as one component of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments (NETCARE). DMS mixing ratios ranged from below the detection limit of 4 to 1155 pptv (median 186 pptv). A set of transfer velocity parameterizations from the literature coupled with our atmospheric and coincident seawater DMS measurements yielded air-sea DMS flux estimates ranging from 0.02-12 μmol m-2 d-1, the first published for this region in summer. Airmass trajectory analysis using FLEXPART-WRF and chemical transport modeling using GEOS-Chem indicated that local sources (Lancaster Sound and Baffin Bay) were the dominant contributors to the DMS measured along the 21 day ship track, with episodic transport from the Hudson Bay System. After adjusting GEOS-Chem oceanic DMS values in the region to match measurements, GEOS-Chem reproduced the major features of the measured time series, but remained biased low overall (median 67 pptv). We investigated non-marine sources that might contribute to this bias, such as DMS emissions from lakes, biomass burning, melt ponds and coastal tundra. While the local marine sources of DMS dominated overall, our results suggest that non-local and possibly non-marine sources episodically contributed strongly to the observed summertime Arctic DMS mixing ratios.

  17. Occurrence and distribution of bacterial tetraether lipids in the Eocene Canadian Arctic paleosols: paleoclimate implications (Invited)

    NASA Astrophysics Data System (ADS)

    Mehay, S.; Jahren, A.; Schubert, B.; Eberle, J. J.; Summons, R. E.

    2010-12-01

    The Early to Middle Eocene (~56-45 Ma) was a “greenhouse” interval with average global temperatures warmer than any other time in the Cenozoic. This period was characterized by warm climates at high latitude leading to lush forests and the arrival of new mammal groups north of the Arctic Circle (>73°N). Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids characteristic of certain archaea and bacteria and it has been demonstrated that branched and cyclic GDGTs derived from soil bacteria vary in structure as a function of environmental factors. Proxies based on the relative abundances of methyl branched and cyclopentyl bacterial tetraethers are hypothesized to correlate with mean annual air temperature and soil pH. Here we present the occurrence and distribution of GDGTs in a range of paleosol and sediment samples from Axel Heiberg Island and Ellesmere Island, Nunavut (eastern Canadian Arctic) and Banks Island in the Northwest Territories (western Canadian Arctic). Preliminary results on 11 paleosol samples from the middle Eocene-aged Geodetic Hills Fossil Forest on Axel Heiberg Island indicate a mean annual air temperature of about 9°C. Earlier paleotemperature estimates for Axel Heiberg Island led to values ranging from 9°C to 15°C for the Middle Eocene. Recent temperature prediction for Ellesmere Island (Early Eocene) based upon oxygen isotope ratios of biogenic phosphate from mammal and fish fossils led to ~8°C. In contrast, GDGTs from a marine sedimentary sequence from Lomonosov Ridge in the central Arctic Ocean led to much higher Early Eocene temperature. Thus, the evaluation of the paleotemperature for the Early to Middle Eocene is still a subject of controversy. Ongoing GDGTs analysis of samples from Ellesmere and Banks Islands should give a more comprehensive paleoenvironmental description of the Eocene Arctic. Differences observed between the various paleotemperature estimates will also be discussed. GDGTs distributions are

  18. Atmospheric methane oxidizers are present and active in Canadian high Arctic soils.

    PubMed

    Martineau, Christine; Pan, Yao; Bodrossy, Levente; Yergeau, Etienne; Whyte, Lyle G; Greer, Charles W

    2014-08-01

    The melting of permafrost and the associated potential for methane emissions to the atmosphere are major concerns in the context of global warming. However, soils can also represent a significant sink for methane through the activity of methane-oxidizing bacteria (MOB). In this study, we looked at the activity, diversity, and community structure of MOB at two sampling depths within the active layer in three soils from the Canadian high Arctic. These soils had the capacity to oxidize methane at low (15 ppm) and high (1000 ppm) methane concentrations, but rates differed greatly depending on the sampling date, depth, and site. The pmoA gene sequences related to two genotypes of uncultured MOB involved in atmospheric methane oxidation, the 'upland soil cluster gamma' and the 'upland soil cluster alpha', were detected in soils with near neutral and acidic pH, respectively. Other groups of MOB, including Type I methanotrophs and the 'Cluster 1' genotype, were also detected, indicating a broader diversity of MOB than previously reported for Arctic soils. Overall, the results reported here showed that methane oxidation at both low and high methane concentrations occurs in high Arctic soils and revealed that different groups of atmospheric MOB inhabit these soils.

  19. Photodemethylation of Methylmercury in Eastern Canadian Arctic Thaw Pond and Lake Ecosystems.

    PubMed

    Girard, Catherine; Leclerc, Maxime; Amyot, Marc

    2016-04-01

    Permafrost thaw ponds of the warming Eastern Canadian Arctic are major landscape constituents and often display high levels of methylmercury (MeHg). We examined photodegradation potentials in high-dissolved organic matter (DOC) thaw ponds on Bylot Island (BYL) and a low-DOC oligotrophic lake on Cornwallis Island (Char Lake). In BYL, the ambient MeHg photodemethylation (PD) rate over 48 h of solar exposure was 6.1 × 10(-3) m(2) E(-1), and the rate in MeHg amended samples was 9.3 × 10(-3) m(2) E(-1). In contrast, in low-DOC Char Lake, PD was only observed in the first 12 h, which suggests that PD may not be an important loss process in polar desert lakes. Thioglycolic acid addition slowed PD, while glutathione and chlorides did not impact northern PD rates. During an ecosystem-wide experiment conducted in a covered BYL pond, there was neither net MeHg increase in the dark nor loss attributable to PD following re-exposure to sunlight. We propose that high-DOC Arctic thaw ponds are more prone to MeHg PD than nearby oligotrophic lakes, likely through photoproduction of reactive species rather than via thiol complexation. However, at the ecosystem level, these ponds, which are widespread through the Arctic, remain likely sources of MeHg for neighboring systems. PMID:26938195

  20. Inuit Student Teachers' Agency, Positioning and Symbolic Action: Reflections from a "Qallunaat" on Music Teaching in the Canadian Arctic

    ERIC Educational Resources Information Center

    Russell, Joan

    2006-01-01

    This article examines how three Inuit student teachers in the Nunavut Teacher Education Program invested their "social and cultural capital" during a music course for classroom teachers, which the author taught in the Canadian Arctic. She describes how, through the musical games they invented for use in Inuit classrooms, these students positioned…

  1. Surface water types in the Western Canadian Arctic: geochemical evolution and aquatic carbon transport

    NASA Astrophysics Data System (ADS)

    Dean, Joshua F.; Billett, Mike F.; Dinsmore, Kerry J.; Lessels, Jason S.; Street, Lorna; Washbourne, Ian; Subke, Jens-Arne; Tetzlaff, Doerthe; Baxter, Robert; Wookey, Philip A.

    2015-04-01

    Arctic surface waters are a substantial conduit for terrestrial C flow as well as a potential source of GHGs to the atmosphere - a significant positive feedback to global climate warming and a key component of the net ecosystem carbon balance in permafrost regions. As temperatures rise in the Arctic, permafrost thaw deepens releasing C from the landscape into the aquatic system making streams and lakes increasingly important conduits and reactors of both allochthonous and autochthonous C. The HYDRA project ('Permafrost catchments in transition: hydrological controls on carbon cycling and greenhouse gas budgets'), aims to quantify the assimilation of C and the controls of C movement between the plant-soil-water-atmosphere continuum. The specific aspect of the project presented here considers the different aquatic pathways in warming Arctic permafrost catchments, and the potential role that they play in GHG emissions and aquatic C cycling. This study presents the surface water geochemistry of Siksik Creek, a small (

  2. Determining diatom ecotones and their relationship to terrestrial ecoregion designations in the central Canadian Arctic Islands.

    PubMed

    Antoniades, Dermot; Douglas, Marianne S V; Michelutti, Neal; Smol, John P

    2014-08-01

    Ecotones are key areas for the detection of global change because many are predicted to move with shifts in climate. Prince of Wales Island, in the Canadian Arctic Archipelago, spans the transition between mid- to high-Arctic ecoregions. We analyzed limnological variables and recent diatom assemblages from its lakes and ponds to determine if assemblages reflected this ecotone. Limnological gradients were short, and water chemistry explained 20.0% of diatom variance in a redundancy analysis (RDA), driven primarily by dissolved organic carbon, Ca and SO4 . Most taxa were small, benthic forms; key taxa such as planktonic Cyclotella species were restricted to the warmer, southern portion of the study area, while benthic Staurosirella were associated with larger, ice-dominated lakes. Nonetheless, there were no significant changes in diatom assemblages across the mid- to high-Arctic ecoregion boundary. We combined our data set with one from nearby Cornwallis Island to expand the study area and lengthen its environmental gradients. Within this expanded data set, 40.6% of the diatom variance was explained by a combination of water chemistry and geographic variables, and significant relationships were revealed between diatom distributions and key limnological variables, including pH, specific conductivity, and chl-a. Using principal coordinates analysis, we estimated community turnover with latitude and applied piecewise linear regression to determine diatom ecotone positions. A pronounced transition was present between Prince of Wales Island and the colder, more northerly Cornwallis Island. These data will be important in detecting any future northward ecotone movement in response to predicted Arctic climate warming in this highly sensitive region.

  3. Determining diatom ecotones and their relationship to terrestrial ecoregion designations in the central Canadian Arctic Islands.

    PubMed

    Antoniades, Dermot; Douglas, Marianne S V; Michelutti, Neal; Smol, John P

    2014-08-01

    Ecotones are key areas for the detection of global change because many are predicted to move with shifts in climate. Prince of Wales Island, in the Canadian Arctic Archipelago, spans the transition between mid- to high-Arctic ecoregions. We analyzed limnological variables and recent diatom assemblages from its lakes and ponds to determine if assemblages reflected this ecotone. Limnological gradients were short, and water chemistry explained 20.0% of diatom variance in a redundancy analysis (RDA), driven primarily by dissolved organic carbon, Ca and SO4 . Most taxa were small, benthic forms; key taxa such as planktonic Cyclotella species were restricted to the warmer, southern portion of the study area, while benthic Staurosirella were associated with larger, ice-dominated lakes. Nonetheless, there were no significant changes in diatom assemblages across the mid- to high-Arctic ecoregion boundary. We combined our data set with one from nearby Cornwallis Island to expand the study area and lengthen its environmental gradients. Within this expanded data set, 40.6% of the diatom variance was explained by a combination of water chemistry and geographic variables, and significant relationships were revealed between diatom distributions and key limnological variables, including pH, specific conductivity, and chl-a. Using principal coordinates analysis, we estimated community turnover with latitude and applied piecewise linear regression to determine diatom ecotone positions. A pronounced transition was present between Prince of Wales Island and the colder, more northerly Cornwallis Island. These data will be important in detecting any future northward ecotone movement in response to predicted Arctic climate warming in this highly sensitive region. PMID:26988446

  4. Methylated mercury species in marine waters of the Canadian high and sub Arctic.

    PubMed

    Kirk, Jane L; St Louis, Vincent L; Hintelmann, Holger; Lehnherr, Igor; Else, Brent; Poissant, Laurier

    2008-11-15

    Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dimethyl Hg (DMHg) was examined in marine waters of the Canadian Arctic Archipelago (CAA), Hudson Strait, and Hudson Bay. Concentrations of THg were low throughout the water column in all regions sampled (mean +/- standard deviation; 0.40 +/- 0.47 ng L(-1)). Concentrations of MMHg were also generally low atthe surface (23.8 +/- 9.9 pg L(-1)); however at mid- and bottom depths, MMHg was present at concentrations sufficient to initiate bioaccumulation of MMHg through Arctic marine foodwebs (maximum 178 pg L(-1); 70.3 +/- 37.3 pg L(-1)). In addition, at mid- and bottom depths, the % of THg that was MMHg was high (maximum 66%; 28 +/- 16%), suggesting that active methylation of inorganic Hg(II) occurs in deep Arctic marine waters. Interestingly, there was a constant, near 1:1, ratio between concentrations of MMHg and DMHg at all sites and depths, suggesting that methylated Hg species are in equilibrium with each other and/or are produced by similar processes throughout the water column. Our results also demonstrate that oceanographic processes, such as water regeneration and vertical mixing, affect Hg distribution in marine waters. Vertical mixing, for example, likely transported MMHg and DMHg upward from production zones at some sites, resulting in elevated concentrations of these species in surface waters (up to 68.0 pg L(-1)) where primary production and thus uptake of MMHg by biota is potentially highest. Finally, calculated instantaneous ocean-atmosphere fluxes of gaseous Hg species demonstrated that Arctic marine waters are a substantial source of DMHg and GEM to the atmosphere (27.3 +/- 47.8 and 130 +/- 138 ng m(-2) day(-1), respectively) during the ice-free season. PMID:19068819

  5. The Unexpected Re-Growth of Ice-Entombed Bryophytes in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    La Farge, C.

    2014-12-01

    The rapid retreat of glaciers and ice caps throughout the Canadian Arctic is exposing pristine vegetation preserved beneath cold-based ice. For the past half century this vegetation has been consistently reported as dead. This interpretation has been overturned by the successful re-growth of Little Ice Age (1550-1850 AD) bryophytes emerging from the Teardrop Glacier, Sverdrup Pass, Ellesmere Island (79° N) collected in 2009. Some populations showed regeneration in the field and lab experiments confirmed their capacity to regrow. The species richness of these subglacial populations is exceptional, comprising >62 species that represent 44% of the extant bryophyte flora of Sverdrup Pass. Cold-based glaciers are known to provide critical habitats for a variety of microbiota (i.e., fungi, algae, cyanobacteria, bacteria and viruses) in high latitude ecosystems. The regeneration of Little Ice Age bryophytes fundamentally expands the concept of biological refugia to land plants that was previously restricted to survival above and beyond glacial margins. Given this novel understanding of subglacial ecosystems, fieldwork is now being extended southward to plateau ice caps on Baffin Island, Nunavut, where ice retreat is exposing subglacial populations of greater antiquity (thousands to tens of thousands of radiocarbon years before present). Bryophytes by nature are totipotent (stem cell equivalency) and poikilohydric (desiccation tolerance), which facilitate their unique adaptation to extreme environments. Continuity of the Arctic bryophyte flora extends back through the Holocene to the late Tertiary [Beaufort Fm, 2-5 Ma], when the majority of taxa were the same, based on records spanning the archipelago from Ellesmere to Banks Island. This record contrasts with that of vascular plants, which have had a number of extinctions, necessitating recolonization of arctic populations from outside the region. The biological significance of a stable bryophyte element highlights their

  6. Recent progress on our understanding of the biological effects of mercury in fish and wildlife in the Canadian Arctic.

    PubMed

    Scheuhammer, Anton; Braune, Birgit; Chan, Hing Man; Frouin, Héloïse; Krey, Anke; Letcher, Robert; Loseto, Lisa; Noël, Marie; Ostertag, Sonja; Ross, Peter; Wayland, Mark

    2015-03-15

    This review summarizes our current state of knowledge regarding the potential biological effects of mercury (Hg) exposure on fish and wildlife in the Canadian Arctic. Although Hg in most freshwater fish from northern Canada was not sufficiently elevated to be of concern, a few lakes in the Northwest Territories and Nunavut contained fish of certain species (e.g. northern pike, Arctic char) whose muscle Hg concentrations exceeded an estimated threshold range (0.5-1.0 μg g(-1) wet weight) within which adverse biological effects begin to occur. Marine fish species generally had substantially lower Hg concentrations than freshwater fish; but the Greenland shark, a long-lived predatory species, had mean muscle Hg concentrations exceeding the threshold range for possible effects on health or reproduction. An examination of recent egg Hg concentrations for marine birds from the Canadian Arctic indicated that mean Hg concentration in ivory gulls from Seymour Island fell within the threshold range associated with adverse effects on reproduction in birds. Mercury concentrations in brain tissue of beluga whales and polar bears were generally lower than levels associated with neurotoxicity in mammals, but were sometimes high enough to cause subtle neurochemical changes that can precede overt neurotoxicity. Harbour seals from western Hudson Bay had elevated mean liver Hg concentrations along with comparatively high muscle Hg concentrations indicating potential health effects from methylmercury (MeHg) exposure on this subpopulation. Because current information is generally insufficient to determine with confidence whether Hg exposure is impacting the health of specific fish or wildlife populations in the Canadian Arctic, biological effects studies should comprise a major focus of future Hg research in the Canadian Arctic. Additionally, studies on cellular interactions between Hg and selenium (Se) are required to better account for potential protective effects of Se on Hg

  7. Recent progress on our understanding of the biological effects of mercury in fish and wildlife in the Canadian Arctic.

    PubMed

    Scheuhammer, Anton; Braune, Birgit; Chan, Hing Man; Frouin, Héloïse; Krey, Anke; Letcher, Robert; Loseto, Lisa; Noël, Marie; Ostertag, Sonja; Ross, Peter; Wayland, Mark

    2015-03-15

    This review summarizes our current state of knowledge regarding the potential biological effects of mercury (Hg) exposure on fish and wildlife in the Canadian Arctic. Although Hg in most freshwater fish from northern Canada was not sufficiently elevated to be of concern, a few lakes in the Northwest Territories and Nunavut contained fish of certain species (e.g. northern pike, Arctic char) whose muscle Hg concentrations exceeded an estimated threshold range (0.5-1.0 μg g(-1) wet weight) within which adverse biological effects begin to occur. Marine fish species generally had substantially lower Hg concentrations than freshwater fish; but the Greenland shark, a long-lived predatory species, had mean muscle Hg concentrations exceeding the threshold range for possible effects on health or reproduction. An examination of recent egg Hg concentrations for marine birds from the Canadian Arctic indicated that mean Hg concentration in ivory gulls from Seymour Island fell within the threshold range associated with adverse effects on reproduction in birds. Mercury concentrations in brain tissue of beluga whales and polar bears were generally lower than levels associated with neurotoxicity in mammals, but were sometimes high enough to cause subtle neurochemical changes that can precede overt neurotoxicity. Harbour seals from western Hudson Bay had elevated mean liver Hg concentrations along with comparatively high muscle Hg concentrations indicating potential health effects from methylmercury (MeHg) exposure on this subpopulation. Because current information is generally insufficient to determine with confidence whether Hg exposure is impacting the health of specific fish or wildlife populations in the Canadian Arctic, biological effects studies should comprise a major focus of future Hg research in the Canadian Arctic. Additionally, studies on cellular interactions between Hg and selenium (Se) are required to better account for potential protective effects of Se on Hg

  8. Measurements of the dissolved inorganic carbon system and associated biogeochemical parameters in the Canadian Arctic, 1974-2009

    NASA Astrophysics Data System (ADS)

    Giesbrecht, K. E.; Miller, L. A.; Zimmermann, S.; Carmack, E.; Johnson, W. K.; Macdonald, R. W.; McLaughlin, F.; Mucci, A.; Williams, W. J.; Wong, C. S.; Yamamoto-Kawai, M.

    2013-06-01

    We have assembled and conducted primary quality control on previously publically-unavailable water column measurements of the dissolved inorganic carbon system and associated biogeochemical parameters (oxygen, nutrients, etc.) made on 25 cruises in the subarctic and Arctic regions dating from as far back as 1974. The measurements are primarily from the western side of the Canadian Arctic, but also include data ranging from the North Pacific to the Gulf of St. Lawrence. The data were subjected to primary quality control (QC) to identify outliers and obvious errors. This dataset incorporates over four thousand individual measurements of total inorganic carbon (TIC), alkalinity, and pH from the Canadian Arctic over a period of more than 30 yr and provides an opportunity to increase our understanding of temporal changes in the inorganic carbon system in northern waters and the Arctic Ocean. The dataset is available for download on the CDIAC website: Arctic_Database/"target="_blank">http://cdiac.ornl.gov/ftp/oceans/IOS_Arctic_Database/ (doi:10.3334/CDIAC/OTG.IOS_ARCT_CARBN).

  9. Measurements of the dissolved inorganic carbon system and associated biogeochemical parameters in the Canadian Arctic, 1974-2009

    NASA Astrophysics Data System (ADS)

    Giesbrecht, K. E.; Miller, L. A.; Davelaar, M.; Zimmermann, S.; Carmack, E.; Johnson, W. K.; Macdonald, R. W.; McLaughlin, F.; Mucci, A.; Williams, W. J.; Wong, C. S.; Yamamoto-Kawai, M.

    2014-03-01

    We have assembled and conducted primary quality control on previously publicly unavailable water column measurements of the dissolved inorganic carbon system and associated biogeochemical parameters (oxygen, nutrients, etc.) made on 26 cruises in the subarctic and Arctic regions dating back to 1974. The measurements are primarily from the western side of the Canadian Arctic, but also include data that cover an area ranging from the North Pacific to the Gulf of St. Lawrence. The data were subjected to primary quality control (QC) to identify outliers and obvious errors. This data set incorporates over four thousand individual measurements of total inorganic carbon (TIC), alkalinity, and pH from the Canadian Arctic over a period of more than 30 years and provides an opportunity to increase our understanding of temporal changes in the inorganic carbon system in northern waters and the Arctic Ocean. The data set is available for download on the CDIAC (Carbon Dioxide Information Analysis Center) website: Arctic_Database/"target="_blank">http://cdiac.ornl.gov/ftp/oceans/IOS_Arctic_Database/ (doi:10.3334/CDIAC/OTG.IOS_ARCT_CARBN).

  10. Sinistral Displacement of the Pearya Terrane along the Canadian Arctic Margin

    NASA Astrophysics Data System (ADS)

    McClelland, W.; Malone, S.; von Gosen, W.; Piepjohn, K.; Läufer, A.

    2012-12-01

    Structural and geochronologic observations from the Pearya terrane, northern Ellesmere Island, provide insight into the origin of the Canadian Arctic margin. The composite terrane records amalgamation of various fragments between 475 and 460 Ma and was accreted via sinistral transpression to the northern margin of Laurentia by 425 Ma (Trettin et al., 1991). New U-Pb SHRIMP-RG (USGS/Stanford) data from igneous rocks of the Pearya terrane help refine magmatic components of the composite terrane to include Neoproterozoic arc plutons (ca 960-970 Ma), a Cambrian syenite-monzodiorite complex (Ward Hunt pluton: 539 ± 4 Ma), Ordovician arc magmatism (Ayles Fiord pluton: 475 ± 3 Ma; Cape Richards pluton: 464 ± 3 Ma) and Devonian-Carboniferous magmatism (Petersen Bay plutonic complex: 332 ± 2 Ma). Samples from the Ordovician Taconite River Formation provide unimodal peaks characteristic of arc settings with LA-ICPMS (Arizona LaserChron Center) detrital zircon U/Pb ages ranging from 440 to 480 Ma. The Pearya terrane is cut by the Pearya shear zone, a major ductile structure defined by a thick zone of sub-vertical mylonites that consistently display a sinistral sense of shear. Mylonites exposed at Cape Columbia are cross-cut by leucocratic pegmatite dikes that give a U-Pb zircon age of 453 ± 3.5 Ma. Quartz and feldspar deformation textures coupled with the orientation of a studied dike are consistent with emplacement during late sinistral deformation. Displacement on the Pearya shear zone at or prior to 450 Ma is interpreted to record translation of the Pearya terrane toward or along the north Laurentian margin, outboard of the Franklinian basin, in the early stages of the Baltica-Laurentia Caledonian collision. The Pearya shear zone merges with or is truncated by the Petersen Bay fault, a complex northwest-southeast contractional structure that marks a segment of the Ellesmerian boundary between the Pearya terrane and Franklinian basin. Major structures within the Pearya

  11. Circum-Arctic Resource Appraisal: Estimates of Undiscovered Oil and Gas North of the Arctic Circle

    USGS Publications Warehouse

    Bird, Kenneth J.; Charpentier, Ronald R.; Gautier, Donald L.; Houseknecht, David W.; Klett, Timothy R.; Pitman, Janet K.; Moore, Thomas E.; Schenk, Christopher J.; Tennyson, Marilyn E.; Wandrey, Craig R.

    2008-01-01

    The U.S. Geological Survey (USGS) has completed an assessment of undiscovered conventional oil and gas resources in all areas north of the Arctic Circle. Using a geology-based probabilistic methodology, the USGS estimated the occurrence of undiscovered oil and gas in 33 geologic provinces thought to be prospective for petroleum. The sum of the mean estimates for each province indicates that 90 billion barrels of oil, 1,669 trillion cubic feet of natural gas, and 44 billion barrels of natural gas liquids may remain to be found in the Arctic, of which approximately 84 percent is expected to occur in offshore areas.

  12. Decline of hexachlorocyclohexane in the Arctic atmosphere and reversal of air-sea gas exchange

    NASA Astrophysics Data System (ADS)

    Bidleman, T. F.; Jantunen, L. M.; Falconer, R. L.; Barrie, L. A.; Fellin, P.

    1995-02-01

    Hexachlorocyclohexanes (HCHs) are the most abundant organochlorine pesticides in the arctic atmosphere and ocean surface water. A compilation of measurements made between 1979-93 from stations in the Canadian and Norwegian Arctic and from cruises in the Bering and Chukchi seas indicates that atmospheric concentrations of α-HCH have declined significantly (p < 0.01), with a time for 50% decrease of about 4 y in summer-fall and 6 y in winter-spring. The 1992-93 levels of about 100 pg m-3 are 2-4 fold lower than values in the mid-1980s. The trend in γ-HCH is less pronounced, but a decrease is also suggested from measurements in the Canadian Arctic and the Bering-Chukchi seas. HCHs in ocean surface water have remained relatively constant since the early 1980s. The decline in atmospheric α-HCH has reversed the net direction of air-sea gas exchange to the point where some northern waters are now sources of the pesticide to the atmosphere instead of sinks.

  13. Small thaw ponds: an unaccounted source of methane in the Canadian high Arctic.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Whiticar, Michael J; Galand, Pierre E; Xu, Xiaomei; Lovejoy, Connie

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate.

  14. Small Thaw Ponds: An Unaccounted Source of Methane in the Canadian High Arctic

    PubMed Central

    Negandhi, Karita; Laurion, Isabelle; Whiticar, Michael J.; Galand, Pierre E.; Xu, Xiaomei; Lovejoy, Connie

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, 14C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate. PMID:24236014

  15. Food expenditure patterns in the Canadian Arctic show cause for concern for obesity and chronic disease

    PubMed Central

    2014-01-01

    Background Little is understood about the economic factors that have influenced the nutrition transition from traditional to store-bought foods that are typically high in fat and sugar amongst people living in the Canadian Arctic. This study aims to determine the pattern of household food expenditure in the Canadian Arctic. Method Local food prices were collected over 12 months in six communities in Nunavut and the Northwest Territories. Dietary intake data were collected from 441 adults using a validated quantitative food frequency questionnaire. Money spent on six food groups was calculated along with the cost of energy and selected nutrients per person. Results Participants spent approximately 10% of total food expenditure on each of the food groups of fruit/vegetables, grains and potatoes, and dairy, 17% on traditional meats (e.g. caribou, goose, char, and seal liver), and 20% on non-traditional meats (e.g. beef, pork, chicken, fish, and processed meats). Non-nutrient-dense foods (NNDF) accounted for 34% of food expenditure. Younger participants (<30 years) spent more on NNDF and less on traditional meats compared with the older age groups. Participants with higher levels of formal education spent more on fruit and vegetables and less on traditional meats, when compared with participants with lower levels of formal education. Conclusions Participants spent most household income on NNDF, a possible consequence of generation discrepancy between younger and older participants. The tendency toward NNDF, particularly among youth, should be addressed with an assessment of predictive factors and the development of targeted approaches to population-based interventions. PMID:24739761

  16. Geographic variation of organochlorine concentrations in ringed seals from the Canadian Arctic: A multivariate approach

    SciTech Connect

    Weis, I.M.; Muir, D.

    1995-12-31

    Concentrations of 58 PCB congeners, DDT and its metabolites, chlorinated benzenes, chlordanes, and toxaphene measured in approximately 180 ringed seals (Phoca hispida), collected from the vicinities of 12 communities across the Canadian Arctic in the period 1984--1989, were analyzed statistically. Data were first lipid corrected and log transformed, then subjected to ANCOVA to remove effects of sex and age on measured levels. Sex was a significant factor for all contaminant groups. For DDT and related compounds and for PCBs, young males and females had similar concentrations; concentrations increased significantly with age in males, but not in females. Concentrations of toxaphenes and chlordanes did not show significant age effects. Residuals from a multiple regression on age and sex were subjected to Principal Components Analysis. Component 1 strongly loaded only a group of highly chlorinated PCB congeners (7 or more chlorine substitutions), component 2 loaded chlorinated benzenes strongly, and component 3 loaded a group of less chlorinated PCBs (4 or 5 chlorine substitutions). Few differences among sites were evident in {Sigma}PCBs, {Sigma}DDTs, {Sigma}chlordanes, or {Sigma}toxaphenes. However, geographical pattern was detectable in both factor scores calculated for some of the principal components and in an analysis of proportions of total PCBs represented by single congeners selected to include a range of K{sub ow} and chlorination levels. Less chlorinated congeners represent larger proportions at increasing latitude and decreasing longitude. More chlorinated congeners generally represented higher proportions of total PCBs at higher longitudes and lower latitudes of the Canadian Arctic.

  17. Profile of persistent chlorinated contaminants, including selected chiral compounds, in wolverine (Gulo gulo) livers from the Canadian Arctic.

    PubMed

    Hoekstra, P F; Braune, B M; Wong, C S; Williamson, M; Elkin, B; Muir, D C G

    2003-11-01

    Wolverines (Gulo gulo) are circumpolar omnivores that live throughout the alpine and arctic tundra ecosystem. Wolverine livers were collected at Kugluktuk (Coppermine), NU (n=12) in the western Canadian Arctic to report, for the first time, the residue patterns of persistent organochlorine contaminants (OCs) in this species. The enantiomer fractions (EFs) of several chiral OCs, including PCB atropisomers, in wolverines were also determined. Results were compared to OC concentrations and EFs of chiral contaminants in arctic fox (Alopex lagopus) from Ulukhaqtuuq (Holman), NT (n=20); a closely related species that scavenges the marine and terrestrial arctic environment. The rank order of hepatic concentrations for sum ( summation operator ) OC groups in wolverines were polychlorinated biphenyls ( summation operator PCB)>chlordane-related components ( summation operator CHLOR)>DDT-related compounds ( summation operator DDT)>hexachlorocyclohexane isomers ( summation operator HCHs). The most abundant OC analytes detected in wolverine liver were PCB-153, PCB-180, and oxychlordane (OXY). Wolverine age and gender did not influence OC concentrations, which were comparable to lipid-normalized values in arctic fox. The EFs of several chiral OCs (alpha-HCH, cis- and trans-chlordane, OXY, heptachlor exo-epoxide) and PCB atropisomers (PCB-136, 149) were nonracemic in arctic fox and wolverine liver and similar to those previously calculated in arctic fox and polar bears from Iceland and the Canadian Arctic. Results suggest that these species have similar ability to biotransform OCs. As well, contaminant profiles suggest that terrestrial mammals do not represent the major source of OC exposure to wolverines and that wolverines are scavenging more contaminated prey items, such as marine mammals. While summation operator PCB did not exceed the concentrations associated with mammalian reproductive impairment, future research is required to properly evaluate the potential affect of

  18. Assessment of undiscovered oil and gas in the arctic

    USGS Publications Warehouse

    Gautier, D.L.; Bird, K.J.; Charpentier, R.R.; Grantz, A.; Houseknecht, D.W.; Klett, T.R.; Moore, T.E.; Pitman, J.K.; Schenk, C.J.; Schuenemeyer, J.H.; Sorensen, K.; Tennyson, M.E.; Valin, Z.C.; Wandrey, C.J.

    2009-01-01

    Among the greatest uncertainties in future energy supply and a subject of considerable environmental concern is the amount of oil and gas yet to be found in the Arctic. By using a probabilistic geologybased methodology, the United States Geological Survey has assessed the area north of the Arctic Circle and concluded that about 30% of the world's undiscovered gas and 13% of the world's undiscovered oil may be found there, mostly offshore under less than 500 meters of water. Undiscovered natural gas is three times more abundant than oil in the Arctic and is largely concentrated in Russia. Oil resources, although important to the interests of Arctic countries, are probably not sufficient to substantially shift the current geographic pattern of world oil production.

  19. Canadian national gas exporters foresee end of price slump

    SciTech Connect

    Not Available

    1992-06-08

    Canadian natural gas producers exporting to the U.S. market see a faint glimmer of light at the end of a long, dark tunnel. Prices hit a 14 year low at the end of 1991 as a persistent glut sparked fierce competition among producers for spot market sales. Crude oil drilling activity topped gas drilling in 1991 for the first time in several years as explorers pulled back in the face of weak prices. This paper reports that the industry's problems have been compounded by a long-running and still unresolved dispute with state regulators over pricing and pipeline access for the California gas market. Despite these negatives, a number of recent industry studies now paint a moderately optimistic scenario of increasing demand and a halt to the steady decline in prices between now and 1995. The Calgary-based Canadian Energy Research Institute (CERI) released a study this spring indicating the gas surplus in western Canada is steadily dissipating.

  20. Invasion, establishment, and range expansion of two parasitic nematodes in the Canadian Arctic.

    PubMed

    Kutz, Susan J; Checkley, Sylvia; Verocai, Guilherme G; Dumond, Mathieu; Hoberg, Eric P; Peacock, Rod; Wu, Jessica P; Orsel, Karin; Seegers, Karin; Warren, Amy L; Abrams, Arthur

    2013-11-01

    Climate warming is occurring at an unprecedented rate in the Arctic and is having profound effects on host-parasite interactions, including range expansion. Recently, two species of protostrongylid nematodes have emerged for the first time in muskoxen and caribou on Victoria Island in the western Canadian Arctic Archipelago. Umingmakstrongylus pallikuukensis, the muskox lungworm, was detected for the first time in 2008 in muskoxen at a community hunt on the southwest corner of the island and by 2012, it was found several hundred kilometers east in commercially harvested muskoxen near the town of Ikaluktutiak. In 2010, Varestrongylus sp., a recently discovered lungworm of caribou and muskoxen was found in muskoxen near Ikaluktutiak and has been found annually in this area since then. Whereas invasion of the island by U. pallikuukensis appears to have been mediated by stochastic movement of muskoxen from the mainland to the southwest corner of the island, Varestrongylus has likely been introduced at several times and locations by the seasonal migration of caribou between the island and the mainland. A newly permissive climate, now suitable for completion of the parasite life cycles in a single summer, likely facilitated the initial establishment and now drives range expansion for both parasites.

  1. Multiproxy paleoecological evidence of Holocene climatic changes on the Boothia Peninsula, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Fortin, Marie-Claude; Gajewski, Konrad

    2016-05-01

    A study of chironomid remains in the sediments of Lake JR01 on the Boothia Peninsula in the Central Canadian Arctic provides a high-resolution record of mean July air temperatures for the last 6.9 ka. Diatom and pollen studies have previously been published from this core. Peak Holocene temperatures occurred prior to 5.0 ka, a time when overall aquatic and terrestrial biological production was high. Chironomid-inferred summer air temperatures reached up to 7.5°C during this period. The region of Lake JR01 cooled over the mid- to late-Holocene, with high biological production between 6.1 and 5.4 ka. Biological production decreased again at ˜2 ka and the rate of cooling increased in the past 2 ka, with coolest temperatures occurring between 0.46 and 0.36 ka, coinciding with the Little Ice Age. Although biological production increased in the last 150 yr, the reconstructed temperatures do not indicate a warming during this time. During transitions, either warming or cooling, chironomid production increases, suggesting an ecosystem-level response to climate variability, seen at a number of lakes across the Arctic.

  2. Microbial Functional Potential and Community Composition in Permafrost-Affected Soils of the NW Canadian Arctic

    PubMed Central

    Frank-Fahle, Béatrice A.; Yergeau, Étienne; Greer, Charles W.; Lantuit, Hugues; Wagner, Dirk

    2014-01-01

    Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic. PMID:24416279

  3. Nitrogen fixation and identification of potential diazotrophs in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Blais, Marjolaine; Tremblay, Jean-Éric; Jungblut, Anne D.; Gagnon, Jonathan; Martin, Johannie; Thaler, Mary; Lovejoy, Connie

    2012-09-01

    Global gaseous nitrogen (N2) fixation rates may be underestimated and data is lacking from many regions without conspicuous diazotrophic cyanobacteria, such as cold oceans. We estimated N2 fixation rates at diverse sites in the Canadian Arctic, including the mouth of the Mackenzie River, the offshore Beaufort Sea, Lancaster Sound, Baffin Bay and a river influenced fjord. We also identified potential diazotrophic communities using a targeted survey of the nifH gene. Nitrogen fixation rates ranged from 0.02 nmol N L-1 d-1 in Baffin Bay to 4.45 nmol N L-1 d-1 in the Mackenzie River plume. Sequences recovered from the nifH gene survey belonged mainly to Cluster III, a group of nifH sequences associated with diverse microorganisms, with some α- andγ-proteobacterianifH genes at most sites. Cyanobacteria nifH genes with best matches to Nostocales, which are common in Arctic freshwaters, were recovered from the marine Beaufort Sea. The geographic pattern of N2 fixation rates and nifHgene identities suggest that the Mackenzie River is the source of a diazotrophic community that contributes new nitrogen to the nitrogen-depleted surface waters of the Beaufort Sea. This first record of N2 fixation at high latitudes refines our understanding of the global nitrogen budget.

  4. Microbial functional potential and community composition in permafrost-affected soils of the NW Canadian Arctic.

    PubMed

    Frank-Fahle, Béatrice A; Yergeau, Etienne; Greer, Charles W; Lantuit, Hugues; Wagner, Dirk

    2014-01-01

    Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic.

  5. Brown snow: A long-range transport event in the Canadian Arctic

    SciTech Connect

    Welch, H.E.; Muir, D.C.G.; Billeck, B.N.; Lockhart, W.L.; Brunskill, G.J.; Kling, H.J. ); Olson, M.P. ); Lemoine, R.M. )

    1991-02-01

    The authors document the occurrence of a long-range transport event that deposited thousands of tons of fine particulates on the District of Keewatin, central Canadian Arctic, {approximately}63 N. Air mass trajectories, clay mineral composition, soot particles, and visible organic remains point to Asian sources for the brown snow material, probably western China. Semivolatile organic pollutants detected in the brown snow included polycyclic aromatic hydrocarbons ({Sigma}PAH), PCB congeners, and DDT-related compounds ({Sigma}DDT), polychlorinated camphenes (PCCs), as well as the herbicide trifuluralin and insecticides methoxychlor, endosulfan, and hexachlorocyclohexane (HCH). {Sigma}PAH, PCB, and PCC concentrations were within the range reported in other studies of Arctic snow but {Sigma}DDT levels were 2-10 times higher than previous reports. High molecular weight PAH may have been associated with soot particles in the brown snow but evidence for Asian sources of the pesticides was not strong because of unknown source signal strengths and possible atmospheric transformations of the compounds. Fluxes of these pollutants were also determined by analyzing sediment cores from two small headwater lakes near the sampling site. The quantities of pollutants deposited in this single event may have comprised a significant fraction (>10%) of total annual input {Sigma}PAH and {Sigma}DDT, as determined from lake sedimentation records.

  6. Invasion, establishment, and range expansion of two parasitic nematodes in the Canadian Arctic.

    PubMed

    Kutz, Susan J; Checkley, Sylvia; Verocai, Guilherme G; Dumond, Mathieu; Hoberg, Eric P; Peacock, Rod; Wu, Jessica P; Orsel, Karin; Seegers, Karin; Warren, Amy L; Abrams, Arthur

    2013-11-01

    Climate warming is occurring at an unprecedented rate in the Arctic and is having profound effects on host-parasite interactions, including range expansion. Recently, two species of protostrongylid nematodes have emerged for the first time in muskoxen and caribou on Victoria Island in the western Canadian Arctic Archipelago. Umingmakstrongylus pallikuukensis, the muskox lungworm, was detected for the first time in 2008 in muskoxen at a community hunt on the southwest corner of the island and by 2012, it was found several hundred kilometers east in commercially harvested muskoxen near the town of Ikaluktutiak. In 2010, Varestrongylus sp., a recently discovered lungworm of caribou and muskoxen was found in muskoxen near Ikaluktutiak and has been found annually in this area since then. Whereas invasion of the island by U. pallikuukensis appears to have been mediated by stochastic movement of muskoxen from the mainland to the southwest corner of the island, Varestrongylus has likely been introduced at several times and locations by the seasonal migration of caribou between the island and the mainland. A newly permissive climate, now suitable for completion of the parasite life cycles in a single summer, likely facilitated the initial establishment and now drives range expansion for both parasites. PMID:23828740

  7. Exchanges of volume, heat and freshwater through the Canadian Arctic Archipelago: a numerical study.

    NASA Astrophysics Data System (ADS)

    Grivault, Nathan; Hu, Xianmin; Myers, Paul G.

    2016-04-01

    The Canadian Arctic Archipelago (CAA) is a tangle of shallow basins interlinked by narrow straits. It is the main pathway of liquid freshwater from the Arctic Ocean to North Atlantic. It also receives runoff from the Mackenzie River and the glaciers of the different islands that composes the archipelago. This study is based on a set of numerical experiments using a regional configuration of the coupled ocean/sea-ice general circulation model NEMO. We consider a long-term hindcast (1958-2014) as well as the more recent period (2002-2014) using high resolution inter-annual forcing from Environment Canada. We used an improved mapping of runoff to ensure correct amounts of freshwater are added to the system. We evaluate the flow pathways through the CAA, as well as the transport of volume, heat and freshwater. Results are evaluated against observational sections. We also look at the variability and the dynamics driving it. Passive tracers are used to complement the analysis.

  8. Multiproxy paleoecological evidence of Holocene climatic changes on the Boothia Peninsula, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Fortin, Marie-Claude; Gajewski, Konrad

    2016-05-01

    A study of chironomid remains in the sediments of Lake JR01 on the Boothia Peninsula in the Central Canadian Arctic provides a high-resolution record of mean July air temperatures for the last 6.9 ka. Diatom and pollen studies have previously been published from this core. Peak Holocene temperatures occurred prior to 5.0 ka, a time when overall aquatic and terrestrial biological production was high. Chironomid-inferred summer air temperatures reached up to 7.5°C during this period. The region of Lake JR01 cooled over the mid- to late-Holocene, with high biological production between 6.1 and 5.4 ka. Biological production decreased again at ∼2 ka and the rate of cooling increased in the past 2 ka, with coolest temperatures occurring between 0.46 and 0.36 ka, coinciding with the Little Ice Age. Although biological production increased in the last 150 yr, the reconstructed temperatures do not indicate a warming during this time. During transitions, either warming or cooling, chironomid production increases, suggesting an ecosystem-level response to climate variability, seen at a number of lakes across the Arctic.

  9. Extreme low sea ice years in the Canadian Arctic Archipelago: 1998 versus 2007

    NASA Astrophysics Data System (ADS)

    Howell, Stephen E. L.; Tivy, Adrienne; Agnew, Tom; Markus, Thorsten; Derksen, Chris

    2010-10-01

    Extreme sea ice minima were observed within the Canadian Arctic Archipelago (CAA) during 1998 and 2007. The September average sea ice area was 2.90 and 2.65 standardized anomalies below the historical 1968-1996 climatology for 1998 and 2007, respectively. October sea ice area for 1998 was a staggering 4.45 standardized anomalies below the historical 1968-1996 climatology and 2007 was lower by 3.36 standardized anomalies. We examine the role of thermodynamic and dynamic forcing on CAA sea ice that was responsible for its extreme loss in 1998 and 2007. Thermodynamic forcing on the sea ice was concentrated over 1 month in 2007 facilitating rapid melt, contrasted against a long melt season in 1998. This variation was attributed to anomalously warm air temperatures in June, September, and October for 1998 compared to anomalously warm temperatures in July for 2007. Sea ice dynamics contributed to the 1998 minimum by inhibiting replenishment from the Arctic Ocean but actually facilitated replenishment in 2007 thereby preventing record low conditions. Replenishment was driven by dissimilarities in sea level pressure patterns over the CAA during these extreme years. Evidence for preconditioned thinning was apparent leading up to 2007 but not strongly apparent for 1998. Remarkably, at the onset of 1998 melt season, multi-year ice area within the CAA was 11% more than the historical climatology and 48% more than at the start of the 2007 melt season yet an extreme minima was still reached.

  10. Atmospheric mercury in the Canadian Arctic. Part I: a review of recent field measurements.

    PubMed

    Steffen, Alexandra; Lehnherr, Igor; Cole, Amanda; Ariya, Parisa; Dastoor, Ashu; Durnford, Dorothy; Kirk, Jane; Pilote, Martin

    2015-03-15

    Long-range atmospheric transport and deposition are important sources of mercury (Hg) to Arctic aquatic and terrestrial ecosystems. We review here recent progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements (see Dastoor et al., this issue for a review of modeling studies on the same topics). Redox processes control the speciation of atmospheric Hg, and thus impart an important influence on Hg deposition, particularly during atmospheric mercury depletion events (AMDEs). Bromine radicals were identified as the primary oxidant of atmospheric Hg during AMDEs. Since the start of monitoring at Alert (NU) in 1995, the timing of peak AMDE occurrence has shifted to earlier times in the spring (from May to April) in recent years, and while AMDE frequency and GEM concentrations are correlated with local meteorological conditions, the reasons for this timing-shift are not understood. Mercury is subject to various post-depositional processes in snowpacks and a large portion of deposited oxidized Hg can be reemitted following photoreduction; how much Hg is deposited and reemitted depends on geographical location, meteorological, vegetative and sea-ice conditions, as well as snow chemistry. Halide anions in the snow can stabilize Hg, therefore it is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks. Atmospheric gaseous Hg concentrations have decreased in some parts of the Arctic (e.g., Alert) from 2000 to 2009 but at a rate that was less than that at lower latitudes. Despite numerous recent advances, a number of knowledge gaps remain, including uncertainties in the identification of oxidized Hg species in the air (and how this relates to dry vs. wet deposition), physical-chemical processes in air, snow and water-especially over sea ice-and the relationship between these processes and climate change. PMID:25497576

  11. Neodymium and strontium isotopic composition of the Strand Fiord Basalts: Cretaceous Volcanism in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Weaver, K. L.; Tarduno, J. A.; Depaolo, D. J.

    2006-12-01

    The basalts of the Strand Fiord Formation present on Axel Heiberg and Ellesmere Islands in the high Canadian Arctic erupted ~95 million years ago. They appear to record part of a large magmatic event that may have affected much of the high Arctic region in the Cretaceous. Based on location and general timing, the volcanism has been tentatively linked to both the early activity of the Iceland hotspot and the Alpha ridge, a poorly understood yet prominent topographic feature in the Arctic Ocean Basin. This study attempts to use isotopic composition to better understand the nature of the Strand Fiord basalts and their relationship to nearby volcanic rocks. A section of subaerial basalt flows collected at Dragon Creek on Axel Heiberg Island have been analyzed for Nd- and Sr-isotopic compositions. The basalts have epsilon Nd(0) that range from 0 to +3.9. 87Sr/86Sr(0) values range from 0.70532 to 0.70881. These samples do not preserve the same depleted signature as the nearby Baffin Bay picrites. Volcanic rocks exposed near Audhild Bay on Ellesmere Island are proximal to volcanics of the Strand Fiord formation, but paleomagnetic polarity data indicate they are at least 12 million years younger. The samples from this region have a more depleted signature with epsilon Nd(0) of about 4.5 and 87Sr/86Sr(0) of 0.704. On the basis of these data, we tentatively conclude that the Audhild Bay and Strand Fiord volcanics share a common depleted source but the former shows more evidence of contamination by continental crust.

  12. Landfast ice thickness in the Canadian Arctic Archipelago from observations and models

    NASA Astrophysics Data System (ADS)

    Howell, Stephen E. L.; Laliberté, Frédéric; Kwok, Ron; Derksen, Chris; King, Joshua

    2016-07-01

    Observed and modelled landfast ice thickness variability and trends spanning more than 5 decades within the Canadian Arctic Archipelago (CAA) are summarized. The observed sites (Cambridge Bay, Resolute, Eureka and Alert) represent some of the Arctic's longest records of landfast ice thickness. Observed end-of-winter (maximum) trends of landfast ice thickness (1957-2014) were statistically significant at Cambridge Bay (-4.31 ± 1.4 cm decade-1), Eureka (-4.65 ± 1.7 cm decade-1) and Alert (-4.44 ± 1.6 cm -1) but not at Resolute. Over the 50+-year record, the ice thinned by ˜ 0.24-0.26 m at Cambridge Bay, Eureka and Alert with essentially negligible change at Resolute. Although statistically significant warming in spring and fall was present at all sites, only low correlations between temperature and maximum ice thickness were present; snow depth was found to be more strongly associated with the negative ice thickness trends. Comparison with multi-model simulations from Coupled Model Intercomparison project phase 5 (CMIP5), Ocean Reanalysis Intercomparison (ORA-IP) and Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS) show that although a subset of current generation models have a "reasonable" climatological representation of landfast ice thickness and distribution within the CAA, trends are unrealistic and far exceed observations by up to 2 orders of magnitude. ORA-IP models were found to have positive correlations between temperature and ice thickness over the CAA, a feature that is inconsistent with both observations and coupled models from CMIP5.

  13. Atmospheric mercury in the Canadian Arctic. Part I: a review of recent field measurements.

    PubMed

    Steffen, Alexandra; Lehnherr, Igor; Cole, Amanda; Ariya, Parisa; Dastoor, Ashu; Durnford, Dorothy; Kirk, Jane; Pilote, Martin

    2015-03-15

    Long-range atmospheric transport and deposition are important sources of mercury (Hg) to Arctic aquatic and terrestrial ecosystems. We review here recent progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements (see Dastoor et al., this issue for a review of modeling studies on the same topics). Redox processes control the speciation of atmospheric Hg, and thus impart an important influence on Hg deposition, particularly during atmospheric mercury depletion events (AMDEs). Bromine radicals were identified as the primary oxidant of atmospheric Hg during AMDEs. Since the start of monitoring at Alert (NU) in 1995, the timing of peak AMDE occurrence has shifted to earlier times in the spring (from May to April) in recent years, and while AMDE frequency and GEM concentrations are correlated with local meteorological conditions, the reasons for this timing-shift are not understood. Mercury is subject to various post-depositional processes in snowpacks and a large portion of deposited oxidized Hg can be reemitted following photoreduction; how much Hg is deposited and reemitted depends on geographical location, meteorological, vegetative and sea-ice conditions, as well as snow chemistry. Halide anions in the snow can stabilize Hg, therefore it is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks. Atmospheric gaseous Hg concentrations have decreased in some parts of the Arctic (e.g., Alert) from 2000 to 2009 but at a rate that was less than that at lower latitudes. Despite numerous recent advances, a number of knowledge gaps remain, including uncertainties in the identification of oxidized Hg species in the air (and how this relates to dry vs. wet deposition), physical-chemical processes in air, snow and water-especially over sea ice-and the relationship between these processes and climate change.

  14. Atmospheric forcing on the Canadian Arctic Archipelago freshwater outflow and implications for the Labrador Sea variability

    NASA Astrophysics Data System (ADS)

    Houssais, Marie-NoëLle; Herbaut, Christophe

    2011-08-01

    The variability of the freshwater export through the Canadian Arctic Archipelago (CAA) is analyzed using a hindcast simulation forced by surface atmospheric forcing from the ERA40 reanalysis (1958-2001). Although the two channels representing the archipelago in the model are both sensitive to the along-channel sea surface height (SSH) gradient, they appear to have very distinct behaviors. The outflow to Lancaster Sound is shown to be largely controlled by the magnitude of the upstream SSH gradient across McClure Strait. The gradient shows a close link to the wind stress curl in the western Arctic but also to a large-scale SSH anomaly pattern which has a strong signal over the shelf to the south of McClure Strait. The latter has, however, little statistical connection to the SSH variability in the Beaufort Gyre. By contrast, the outflow through Nares Strait responds preferentially to SSH variations in the northern Baffin Bay which are remotely forced by air-sea heat exchanges in the Labrador Sea. The variability is largely coherent between the two outflows and is controlled by a dipolar atmospheric pattern reminiscent of the North Atlantic/Arctic Oscillation. When entering the subpolar gyre, the CAA freshwater outflow remains confined to the Labrador shelf with little impact on the salinity of the interior Labrador Sea and potentially on the convection. The latter is represented by a distinct mode of salinity variability in the western subpolar gyre which is rather influenced by the variability of the sea ice export through Fram Strait.

  15. Sources of Dimethyl Sulfide in the Canadian Arctic Archipelago and Baffin Bay

    NASA Astrophysics Data System (ADS)

    Mungall, E. L.; Croft, B.; Lizotte, M.; Thomas, J. L.; Murphy, J. G.; Levasseur, M.; Martin, R.; Wentzell, J. J. B.; Liggio, J.; Abbatt, J.

    2015-12-01

    Dimethyl sulfide plays a major role in the global sulfur cycle, meaning that it is important to the formation of sulfate aerosol and thus to cloud condensation nuclei populations and cloud formation. The summertime Arctic atmosphere sometimes resides in a cloud condensation nuclei limited regime, making it very susceptible to changes in their number. Despite the interest generated by this situation, dimethyl sulfide has only rarely been measured in the summertime Arctic. This work presents the first high time resolution (10 Hz) DMS mixing ratio measurements for the Eastern Canadian Archipelago and Baffin Bay in summer performed on an icebreaker cruise as one component of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments (NETCARE). Measured mixing ratios ranged from below the detection limit of 4 pptv to 1155 pptv with a median value of 186 pptv. We used transfer velocity parameterizations from the literature to generate the first flux estimates for this region in summer, which ranged from 0.02-12 μmol m-2 d-1. DMS has a lifetime against OH oxidation of 1-2 days, allowing both local sources and transport to play roles in its atmospheric mixing ratio. Through air mass trajectory analysis using FLEXPART-WRF and chemical transport modeling using GEOS-Chem, we have identified the relative contributions of local sources (Lancaster Sound and Baffin Bay) as well as transport from further afield (the Hudson Bay System and the Beaufort Sea) and find that the local sources dominate. GEOS-Chem is able to reproduce the major features of the measured time series, but is biased low overall (median 72 pptv). We discuss non-marine sources that could account for this low bias and estimate the possible contributions to DMS mixing ratios from lakes, biomass burning, melt ponds and coastal tundra. Our results show that local marine sources of DMS dominate the summer Arctic atmosphere, but that non-local and possibly non

  16. Remote sensing the dynamics of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean)

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Ehn, J.; Bélanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-04-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. A direct consequence is an increase in Arctic river discharge with an expectation of increased delivery of organic carbon sequestered in high-latitute soils since the last glacial maximum. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed to an operational stage. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC:SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is validated based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone within which terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future work require the validation of the developed SPM regional algorithm based

  17. Analysis of CCN activity of Arctic aerosol and Canadian biomass burning during summer 2008

    NASA Astrophysics Data System (ADS)

    Lathem, T. L.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Cubison, M. J.; Hecobian, A.; Jimenez, J. L.; Weber, R. J.; Anderson, B. E.; Nenes, A.

    2013-03-01

    The NASA DC-8 aircraft characterized the aerosol properties, chemical composition, and cloud condensation nuclei (CCN) concentrations of the summertime Arctic during the 2008 NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. Air masses characteristic of fresh and aged biomass burning, boreal forest, Arctic background, and anthropogenic industrial pollution were sampled. Observations were spatially extensive (50-85° N and 40-130° W) and exhibit significant variability in aerosol and CCN concentrations. The chemical composition was dominated by highly oxidized organics (66-94% by volume), with a water-soluble mass fraction of more than 50%. The aerosol hygroscopicity parameter, κ, ranged between κ = 0.08-0.32 for all air mass types. Industrial pollution had the lowest κ of 0.08 ± 0.01, while the Arctic background had the highest and most variable κ of 0.32 ± 0.21, resulting from a lower and more variable organic fraction. Both fresh and aged (long-range transported) biomass burning air masses exhibited remarkably similar κ (0.18 ± 0.13), consistent with observed rapid chemical and physical aging of smoke emissions in the atmosphere, even in the vicinity of fresh fires. The organic hygroscopicity (κorg) was parameterized by the volume fraction of water-soluble organic matter (ɛWSOM), with a κ = 0.12, such that κorg = 0.12ɛWSOM. Assuming bulk (size-independent) composition and including the κorg parameterization enabled CCN predictions to within 30% accuracy for nearly all environments sampled. The only exception was for industrial pollution from Canadian oil sands exploration, where an external mixture and size-dependent composition was required. Aerosol mixing state assumptions (internal vs. external) in all other environments did not significantly affect CCN predictions; however, the external mixing assumption provided the best results, even though the available observations could not determine

  18. Analysis of CCN activity of Arctic aerosol and Canadian biomass burning during summer 2008

    NASA Astrophysics Data System (ADS)

    Lathem, T. L.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Cubison, M. J.; Hecobian, A.; Jimenez, J. L.; Weber, R. J.; Anderson, B. E.; Nenes, A.

    2012-09-01

    The NASA DC-8 aircraft characterized the aerosol properties, chemical composition, and cloud condensation nuclei (CCN) concentrations of the summertime Arctic during the 2008 NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. Air masses characteristic of fresh and aged biomass burning, boreal forest, Arctic background, and anthropogenic industrial pollution were sampled. Observations were spatially extensive (50-85° N and 40-130° W) and exhibit significant variability in aerosol and CCN concentrations. The chemical composition was dominated by highly oxidized organics (66-94% by volume), more than half of which was water-soluble. The aerosol hygroscopicity parameter, κ, ranged between κ = 0.1-0.32 for all air mass types. Industrial pollution had the lowest κ of 0.08 ± 0.01, while the Arctic background had the highest and most variable κ of 0.32 ± 0.21, resulting from a lower and more variable organic fraction. Both fresh and aged (long-range transported) biomass burning air masses exhibited remarkably similar κ (0.18 ± 0.13), consistent with observed rapid chemical and physical aging of smoke emissions in the atmosphere, even in the vicinity of fresh fires. The organic hygroscopicity (κorg) was parameterized by the volume fraction of water-soluble organic matter (ϵWSOM), with a κ = 0.12, such that κorg = 0.12ϵWSOM. Assuming bulk (size-independent) composition and including the κorg parameterization enabled CCN predictions to within 30% accuracy for nearly all environments sampled. The only exception was for industrial pollution from Canadian oil sands exploration, where an external mixture and size-dependent composition was required. Aerosol mixing state assumptions (internal vs. external) in all other environments did not significantly affect CCN predictions; however, the external mixing assumption provided the best results, even though the available observations could not

  19. Changes in driftwood delivery to the Canadian Arctic Archipelago: The hypothesis of postglacial oscillations of the transpolar drift

    USGS Publications Warehouse

    Dyke, A.S.; England, J.; Reimnitz, E.; Jette, H.

    1997-01-01

    Driftwood appears to be absent in the Beaufort Gyre but abundant in parts of the Transpolar Drift (TPD), which crosses the Arctic Ocean from the Chukchi Sea to the vicinity of northeastern Greenland. Nearly 300 radiocarbon dates on Holocene driftwood from the Canadian Arctic Archipelago reveal two regions with contrasting histories of driftwood incursion: the region accessible to wood brought into Baffin Bay by the West Greenland Current and the rest of the archipelago, which receives wood from the Arctic Ocean. We hypothesize that when the TPD was deflected westward along northern Greenland, wood was delivered widely to the Canadian Arctic Archipelago; when the TPD exited entirely through Fram Strait via the East Greenland Current, little or no wood was delivered to most of the archipelago, but some continued into Baffin Bay via the West Greenland Current. A split TPD delivered wood to both regions. The regional driftwood incursion histories exhibit multiple maxima and minima that can be explained by this hypothesis. The Larix to Picea ratio of wood arriving in the Canadian Arctic Archipelago has also changed through time. This may indicate varying contributions from Russian versus North American sources, which in turn may indicate variable mixing of wood en route. The inferred discharge paths of the TPD were apparently stable for intervals ranging from several millennia to centuries or perhaps only decades. The last major switch broadly correlates with the onset of Neoglaciation. Variations in the path and strength of the TPD may have important oceanographic and climatic consequences downstream in the North Atlantic Ocean.

  20. Resource utilisation by deep-sea megabenthos in the Canadian High Arctic (Baffin Bay and Parry Channel)

    NASA Astrophysics Data System (ADS)

    Bourgeois, Solveig; Witte, Ursula; Harrison, Ailish M.; Makela, Anni; Kazanidis, Georgios; Archambault, Philippe

    2016-04-01

    Ongoing climate change in the Arctic is causing drastic alteration of the Arctic marine ecosystem functioning, such as shifts in patterns of primary production, and modifying the present tight pelagic-benthic coupling. Subsequently benthic communities, which rely upon organic matter produced in the top layers of the Ocean, will also be affected by these changes. The benthic megafaunal communities play a significant role in ecological processes and ecosystem functioning (i.e. organic matter recycling, bioturbation, food source for the higher trophic levels…). Yet, information is scarce regarding the main food sources for dominant benthic organisms, and therefore the impact of the ongoing changes is difficult to assess. The goal of this study is to investigate the preferential feeding of different carbon sources by megabenthic organisms in the Canadian High Arctic and to identify environmental drivers which explain the observed trends. In summer 2013, benthic megafauna was collected at 9 stations spread along latitudinal (58 to 81°N) and longitudinal (62 to 114°W) transects in the Baffin Bay and Parry Channel, respectively. Carbon and nitrogen bulk stable isotope analyses (δ13C and δ15N) were performed on several species divided into groups according to their feeding type. This study highlights distinct trends in δ13C values of benthic organisms suggesting the importance of both phytoplankton and ice algae as carbon sources for megafauna in the Canadian High Arctic. The importance of physical and biological parameters as drivers of food web structure will be furthermore discussed.

  1. Aerosol Size and Chemical Composition in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Chang, R. Y. W.; Hayes, P. L.; Leaitch, W. R.; Croft, B.; O'Neill, N. T.; Fogal, P.; Drummond, J. R.; Sloan, J. J.

    2015-12-01

    Arctic aerosol have a strong annual cycle, with winter months dominated by long range transport from lower latitudes resulting in high mass loadings. Conversely, local emissions are more prominent in the summer months because of the decreased influence of transported aerosol, allowing us to regularly observe both transported and local aerosol. This study will present observations of aerosol chemical composition and particle number size distribution collected at the Polar Environment Artic Research Laboratory and the Alert Global Atmospheric Watch Observatory at Eureka (80N, 86W) and Alert (82N, 62W), Nunavut, respectively. Summer time observations of the number size distribution reveal a persistent mode of particles centered between 30-50 nm, with occasional bursts of smaller particles. The non-refractory aerosol chemical composition, measured by the Canadian Network for the Detection of Atmospheric Change quadrupole aerosol mass spectrometer, is primarily organic, with contributions from both aged and fresher organic aerosol. Factor analysis will be conducted to better understand these sources. The site at Eureka is more susceptible to long range transport since it is at the top of a mountain ridge (610 m above sea level) and will be compared to the site at Alert on an elevated plain (200 m above sea level). This will allow us to determine the relative contributions from processes and sources at the sites at different elevations. Comparisons with aerosol optical depth and GEOS-Chem model output will also be presented to put these surface measurements into context with the overlying and regional atmosphere. Results from this study contribute to our knowledge of aerosol in the high Arctic.

  2. Modeling ocean and sea ice dynamics of the Canadian Arctic Archipelago: Aspects of forcing

    NASA Astrophysics Data System (ADS)

    Wekerle, Claudia; Wang, Qiang; Danilov, Sergey; Myers, Paul G.; Jung, Thomas; Schröter, Jens

    2013-04-01

    The Canadian Arctic Archipelago (CAA) is one of the main pathways for freshwater exiting the Arctic Ocean. Freshwater exported to the North Atlantic may influence the deep water formation in the Labrador Sea, and thus the meridional overturning circulation. Modeling ocean and sea ice conditions of the CAA is difficult because of narrow straits and complex coastlines. The Finite-Element Sea-ice Ocean circulation Model (FESOM) configured on a global mesh is applied to assess the volume, freshwater and sea ice transports through the CAA. With a mesh resolution of 5 km in the CAA we are able to accurately resolve complex coastlines. Outside the CAA the mesh is refined to 24 km north of 55°N with a global background resolution of 1.5°. In this study, first, it is shown that the transports modeled with FESOM correlate well with the available observational data. Second, the model is used to learn about the impact of different atmospheric forcing datasets differing in spatial and temporal resolution (CORE 2 and the Reforecast dataset from Environment Canada). The CORE 2 dataset is on the T62 grid, which is coarse compared to the Reforecast dataset with grid resolution of 0.45° longitude and 0.3° latitude. The temporal resolution of the Reforecast dataset is higher than the CORE 2 dataset (one hourly and 6-hourly data, respectively, for wind, surface temperature and specific humidity fields). The representation of sea ice in the CAA can be improved by using the high resolution atmospheric forcing.

  3. Climate change impacts on continental weathering through the Middle Jurassic to Lower Cretaceous of Sverdrup Basin, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Galloway, Jennifer; Grasby, Stephen; Swindles, Graeme; Dewing, Keith

    2014-05-01

    Jurassic to Cretaceous strata of Sverdrup Basin, Canadian Arctic Archipelago, contain marine and non-marine successions that can be studied to reconstruct ancient paleoclimates and paleoenvironments that are poorly understood in high-latitude regions. We use element geochemistry integrated with palynology to study a continuous Aalenian to Albian-aged succession preserved in the Hoodoo Dome H-37 oil and gas well located on southern Ellef Ringnes Island near the centre of Sverdrup Basin. Cluster analysis (stratigraphically constrained incremental sum of squares; CONISS) is used to delineate four geochemical zones that are broadly coeval with major changes in palyno-assemblages interpreted to reflect changes in regional paleoclimate. Zone 1 (late Aalenian to Bathonian) is characterized by palynomorphs associated with humid and warm climate conditions. The chemical alteration index (CAI) is high in this interval, expected under this a humid and warm climate. A transition to a seasonally arid and warm climate occurred in the Bathonian and persisted until the Kimmeridgian or Valanginian (Zone 2). This interval is characterized by decreased chemical weathering, indicated by a drop in CAI. The onset of Zone 3 (Kimmeridgian or Valanginian to late Barremian or early Aptian) occurs during a transition to humid and cool climate conditions and is associated with a period of regional uplift and rifting. Zone 3 is marked by a substantial and progressive drop in CAI, indicating a transition from a weathering to transport-dominated system, possibly associated with landscape destabilization. Reduced tectonic activity in Zone 4 (early Aptian to early or mid Albian) shows a return to active chemical weathering, possibly associated with landscape stabilization, suggested by a continued increase in pollen from upland coniferous taxa. The geochemical and palynological records of Middle Jurassic to Lower Cretaceous strata of the Hoodoo Dome H-37 oil and gas well show close correlation

  4. Analysis of gas chilling alternatives for Arctic pipelines

    SciTech Connect

    Dvoiris, A.; McMillan, D.K.; Taksa, B.

    1994-12-31

    The operation of buried natural gas pipelines in Arctic regions requires installation of gas chilling facilities at compressor stations. These facilities are required in order to cool compressed pipeline gases to temperatures below that of permanently frozen surrounding soil. If these pipeline gas temperatures are too high, the frozen ground around the pipelines will eventually thaw. This is undesirable for many reasons amongst which are ground settlement and possible catastrophic failure of the pipeline. This paper presents the results of a study which compared several alternative methods of gas chilling for possible application at one of the compressor stations on the proposed new Yamal-Center gas pipeline system in the Russian Arctic. This technical and economic study was performed by Gulf Interstate Engineering (GIE) for GAZPROM, the gas company in Russia that will own and operate this new pipeline system. Geotechnical, climatical and other information provided by GAZPROM, coupled with information developed by GIE, formed the basis for this study.

  5. Anisotropic internal thermal stress in sea ice from the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Hata, Y.; Tremblay, L. B.

    2015-08-01

    Results from an ice stress buoy deployed near the center of a multi-year floe in the Viscount Melville Sound of the Canadian Arctic Archipelago between 10 October 2010 and 17 August 2011 are presented. The position record indicates the landlocked season was approximately 5 months, from 18 January to 22 June, when the sea ice was fast to Melville Island and Victoria Island. Thermal stresses (ranging from -84 to 66 kPa) dominate the internal stress record, with only a few dynamic stress events (˜50 kPa) recorded before the landlocked season. Intriguingly, the thermal stresses are isotropic before the landlocked ice onset and anisotropic during the landlocked season. Two possible causes to explain anisotropy in thermal stresses are considered: preferred c axis alignment of the ice crystal, and land confinement associated with the nearby coastline. The orientation of the principal stresses indicates that land confinement is responsible for the anisotropy. The stress record also clearly shows the presence of residual compressive stresses at the melt onset, suggesting a viscous creep relaxation time constant of several days. Finally, results show an interesting reversal in the sign of the correlation (from negative to positive) between surface air temperature and thermal stress after the onset of surface melt. We attribute this to the onset of water infiltration within sea ice after which colder night temperature leads to refreezing and compressive stresses. To the best of the authors' knowledge, this is the first time that anisotropic thermal stresses have been reported in sea ice.

  6. Temporal trends of organochlorines and mercury in seabird eggs from the Canadian Arctic, 1975-2003.

    PubMed

    Braune, Birgit M

    2007-07-01

    Organochlorine pesticides, PCBs, total mercury and selenium were measured in eggs of thick-billed murres, northern fulmars and black-legged kittiwakes collected from Prince Leopold Island in the Canadian High Arctic between 1975 and 2003. The primary organochlorines found were SigmaPCB, p,p'-DDE, oxychlordane, and hexachlorobenzene (HCB). Most of organochlorines analyzed showed either significant declines or no significant change between 1975 and 2003 in all three species. However, significant increases were observed for SigmaHCH in the kittiwakes and fulmars, and beta-HCH in the murres and fulmars. Mercury increased significantly in eggs of murres and fulmars, whereas mercury in the kittiwakes did not change significantly over the study period. Statistical analyses included stable-nitrogen isotope ratios (delta(15)N) to control for any variation in trophic level over time. Although the contaminant concentrations reported in this study are below published threshold values, mercury and beta-HCH concentrations continue to increase suggesting that continued monitoring is warranted. PMID:17240500

  7. Basal debris entrainment and transport in glaciers of southwestern Bylot Island, Canadian Arctic

    USGS Publications Warehouse

    Zdanowicz, C.M.; Michel, F.A.; Shilts, W.W.

    1996-01-01

    Glaciers on southwestern Bylot Island in the Canadian Arctic flow from an alpine setting in high-grade crystalline Archean terrane, on to coastal lowlands underlain by clastic sedimentary strata of Cretaceous to Tertiary age. We have used the contrasting mineralogy of the substrate as a tool to study subglacial entrainment and transport of debris in two large piedmont glaciers on Bylot Island. High chlorite/ and mica-illite/smectite ratios indicate that most basal debris is derived from crystalline rocks underlying the upper reaches of the glaciers. The subglacial accretion of Cretaceous-Tertiary sediments appears restricted to the lowermost part of the basal zone and is most noticeable near the glaciers' termini. Ice associated with discrete silty-sandy debris layers is characterized by an isotopic signature indicative of refreezing of meltwater at the glacier sole. The compositional, textural and isotopic characteristics of basal sediment and ice lead us to conclude that subglacial entrainment through basal ice accretion occurs in both the upper and marginal parts of the glaciers.

  8. Pipeline under the arctic ice: the Polar Gas Project

    SciTech Connect

    Kaustinen, O.M.

    1982-06-01

    The Polar Gas Project was established in 1972 to determine the best means of moving frontier natural gas from Canada's high arctic to southern markets. Pipeline was found to be most feasible. Several pipeline routings from two major supply areas--the MacKenzie Delta/Beaufort Sea region, and the Sverdrup Basin of the Arctic Islands--have been considered. Field programs to determine the type and ice content of soils along the route have been undertaken. The most challenging engineering aspect will be two marine crossings in arctic waters at either end of Victoria Island, at Dolphin and Union Strait, and at McClure's strait. The ''Ice Hole Bottom Pull'' technique has been recommended, and is illustrated in detail. The planned pipeline demonstration would significantly enhance the current state-of-the-art for deepwater pipelining worldwide.

  9. Mercury concentration in the eggs of four Canadian Arctic-breeding shorebirds not predicted based on their population statuses.

    PubMed

    McCloskey, Meagan; Robinson, Stacey; Smith, Paul A; Forbes, Mark

    2013-01-01

    Methylmercury is a toxic form of mercury which persists in food webs for long periods of time and biomagnifies up successive trophic levels. Shorebirds breeding in the Arctic are exposed to methylmercury, derived from both natural and anthropogenic sources, when they ingest their invertebrate prey. Populations of many shorebird species are believed to be declining and one hypothesis for these declines is that they are due to detrimental effects of contaminants, including methylmercury. To test this hypothesis, we assessed mercury contamination in eggs of four Canadian Arctic-breeding shorebird species: black-bellied plover (Pluvialis squatarola), ruddy turnstone (Arenaria interpres), semipalmated plover (Charadrius semipalmatus) and white-rumped sandpiper (Calidris fuscicollis). Black-bellied plovers and ruddy turnstones are declining in the western hemisphere, whereas white-rumped sandpipers and semipalmated plovers have stable or slightly increasing populations. We found no relationship between egg mercury concentration and population trend for these four shorebird species. Intraspecific variation in mercury concentration was high. Notably, the mercury concentrations were much higher than levels found in a previous study of eggs of the same shorebird species from this same site, suggesting that mercury contamination may be subject to substantial inter-annual variation in the Canadian Arctic food web.

  10. Seasonal changes in nauplii and adults of Calanus hyperboreus (Copepoda) captured in sediment traps, Amundsen Gulf, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Ota, Y.; Hattori, H.; Makabe, R.; Sampei, M.; Tanimura, A.; Sasaki, H.

    Arctic copepods were collected using time-series sediment traps in the Amundsen Gulf, Canadian Arctic, as part of the CASES (Canadian Arctic Shelf Exchange Study) program. Four sediment traps were deployed at three stations (200 m depth for CA15, 200 and 400 m depths for CA18, and 200 m depth for CA20) from October 2003 to July 2004. We collected many copepod nauplii ranging in body length from 155 to 811 μm, among which nauplii (mostly N1-2) of Calanus with a size of ∼190 μm apparently increased in abundance from February to mid-March. Mature-stage adult females (AF) of Calanus hyperboreus were collected in the traps from February to March, and adult males of C. hyperboreus appeared from November to December at all stations. The likely spawning period of these AF coincided with the occurrence period of ∼190 μm-sized nauplii. This finding suggests that these nauplii were derived from C. hyperboreus and that their breeding began at the beginning of November or December at the latest, continuing through April in the Amundsen Gulf.

  11. Spatio-temporal variations and age effect on Toxoplasma gondii seroprevalence in seals from the Canadian Arctic.

    PubMed

    Simon, A; Chambellant, M; Ward, B J; Simard, M; Proulx, J F; Levesque, B; Bigras-Poulin, M; Rousseau, A N; Ogden, N H

    2011-09-01

    Toxoplasmosis is a significant public health threat for Inuit in the Canadian Arctic. This study aimed to investigate arctic seals as a possible food-borne source of infection. Blood samples collected from 828 seals in 7 Canadian Arctic communities from 1999 to 2006 were tested for Toxoplasma gondii antibodies using a direct agglutination test. Polymerase chain reaction (PCR) was used to detect T. gondii DNA in tissues of a subsample of seals. Associations between seal age, sex, species, diet, community and year of capture, and serological test results were investigated by logistic regression. Overall seroprevalence was 10·4% (86/828). All tissues tested were negative by PCR. In ringed seals, seroprevalence was significantly higher in juveniles than in adults (odds ratio=2·44). Overall, seroprevalence varied amongst communities (P=0·0119) and by capture year (P=0·0001). Our study supports the hypothesis that consumption of raw seal meat is a significant source of infection for Inuit. This work raises many questions about the mechanism of transfer of this terrestrial parasite to the marine environment, the preponderance of infection in younger animals and the natural course of infection in seals. Further studies to address these questions are essential to fully understand the health risks for Inuit communities.

  12. Implications of the nutrition transition for vitamin D intake and status in Aboriginal groups in the Canadian Arctic.

    PubMed

    El Hayek Fares, Jessy; Weiler, Hope A

    2016-09-01

    Aboriginal Canadians have low intakes of vitamin D and are shifting away from consumption of traditional foods. Higher body mass index, skin pigmentation, and geographic latitude of residence further predispose Canadian Aboriginal populations to low vitamin D status. Low vitamin D status could compromise bone health and other health outcomes. Studies assessing vitamin D status of different Aboriginal groups are limited. The aim of this review is to examine the literature on vitamin D status and intakes of Canadian Aboriginal populations living in the Arctic. PubMed was searched for relevant articles published from 1983 to 2013. The prevalence of 25-hydroxy vitamin D deficiency ranged from 13.9% to 76.0% among children and adults in the summer. Furthermore, mean vitamin D intakes among all age groups were below the estimated average requirement. As vitamin D deficiency has been recently associated with chronic diseases, and Aboriginal populations living in the Arctic are at high risk for low vitamin D status, their vitamin D status should be assessed regularly across seasons.

  13. Implications of the nutrition transition for vitamin D intake and status in Aboriginal groups in the Canadian Arctic.

    PubMed

    El Hayek Fares, Jessy; Weiler, Hope A

    2016-09-01

    Aboriginal Canadians have low intakes of vitamin D and are shifting away from consumption of traditional foods. Higher body mass index, skin pigmentation, and geographic latitude of residence further predispose Canadian Aboriginal populations to low vitamin D status. Low vitamin D status could compromise bone health and other health outcomes. Studies assessing vitamin D status of different Aboriginal groups are limited. The aim of this review is to examine the literature on vitamin D status and intakes of Canadian Aboriginal populations living in the Arctic. PubMed was searched for relevant articles published from 1983 to 2013. The prevalence of 25-hydroxy vitamin D deficiency ranged from 13.9% to 76.0% among children and adults in the summer. Furthermore, mean vitamin D intakes among all age groups were below the estimated average requirement. As vitamin D deficiency has been recently associated with chronic diseases, and Aboriginal populations living in the Arctic are at high risk for low vitamin D status, their vitamin D status should be assessed regularly across seasons. PMID:27534942

  14. Trends and variability in summer sea ice cover in the Canadian Arctic based on the Canadian Ice Service Digital Archive, 1960-2008 and 1968-2008

    NASA Astrophysics Data System (ADS)

    Tivy, Adrienne; Howell, Stephen E. L.; Alt, Bea; McCourt, Steve; Chagnon, Richard; Crocker, Greg; Carrieres, Tom; Yackel, John J.

    2011-03-01

    The Canadian Ice Service Digital Archive (CISDA) is a compilation of weekly ice charts covering Canadian waters from the early 1960s to present. The main sources of uncertainty in the database are reviewed and the data are validated for use in climate studies before trends and variability in summer averaged sea ice cover are investigated. These data revealed that between 1968 and 2008, summer sea ice cover has decreased by 11.3% ± 2.6% decade-1 in Hudson Bay, 2.9% ± 1.2% decade-1 in the Canadian Arctic Archipelago (CAA), 8.9% ± 3.1% decade-1 in Baffin Bay, and 5.2% ± 2.4% decade-1 in the Beaufort Sea with no significant reductions in multiyear ice. Reductions in sea ice cover are linked to increases in early summer surface air temperature (SAT); significant increases in SAT were observed in every season and they are consistently greater than the pan-Arctic change by up to ˜0.2°C decade-1. Within the CAA and Baffin Bay, the El Niño-Southern Oscillation index correlates well with multiyear ice coverage (positive) and first-year ice coverage (negative) suggesting that El Niño episodes precede summers with more multiyear ice and less first-year ice. Extending the trend calculations back to 1960 along the major shipping routes revealed significant decreases in summer sea ice coverage ranging between 11% and 15% decade-1 along the route through Hudson Bay and 6% and 10% decade-1 along the southern route of the Northwest Passage, the latter is linked to increases in SAT. Between 1960 and 2008, no significant trends were found along the northern western Parry Channel route of the Northwest Passage.

  15. Ten-year trends of atmospheric mercury in the high Arctic compared to Canadian sub-Arctic and mid-latitude sites

    NASA Astrophysics Data System (ADS)

    Cole, A. S.; Steffen, A.; Aspmo Pfaffhuber, K.; Berg, T.; Pilote, M.; Poissant, L.; Tordon, R.; Hung, H.

    2012-08-01

    Global emissions of mercury continue to change at the same time as the Arctic is experiencing ongoing climatic changes. Continuous monitoring of atmospheric mercury provides important information about long-term trends in the balance between transport, chemistry, and deposition of this pollutant in the Arctic atmosphere. Ten-year records of total gaseous mercury (TGM) were analyzed from two high Arctic sites at Alert (Nunavut, Canada) and Zeppelin Station (Svalbard, Norway); one sub-Arctic site at Kuujjuarapik (Nunavik, Québec, Canada); and three temperate Canadian sites at St. Anicet (Québec), Kejimkujik (Nova Scotia) and Egbert (Ontario). Five of the six sites examined show a decreasing trend over this time period. Overall trend estimates at high latitude sites were: -0.9% yr-1 (95% confidence limits: -1.4, 0) at Alert and no trend (-0.5, +0.7) at Zeppelin Station. Faster decreases were observed at the remainder of the sites: -2.1% yr-1 (-3.1, -1.1) at Kuujjuarapik, -1.9% yr-1 (-2.1, -1.8) at St. Anicet, -1.6% yr-1 (-2.4, -1.0) at Kejimkujik and -2.2% yr-1 (-2.8, -1.7) at Egbert. Trends at the sub-Arctic and mid-latitude sites agree with reported decreases in background TGM concentration since 1996 at Mace Head, Ireland, and Cape Point, South Africa, but conflict with estimates showing an increase in global anthropogenic emissions over a similar period. Trends in TGM at the two high Arctic sites were not only less negative (or neutral) overall but much more variable by season. Possible reasons for differences in seasonal and overall trends at the Arctic sites compared to those at lower latitudes are discussed, as well as implications for the Arctic mercury cycle. The first calculations of multi-year trends in reactive gaseous mercury (RGM) and total particulate mercury (TPM) at Alert were also performed, indicating increases from 2002 to 2009 in both RGM and TPM in the spring when concentrations are highest.

  16. Ten-year trends of atmospheric mercury in the high Arctic compared to Canadian sub-Arctic and mid-latitude sites

    NASA Astrophysics Data System (ADS)

    Cole, A. S.; Steffen, A.; Pfaffhuber, K. A.; Berg, T.; Pilote, M.; Poissant, L.; Tordon, R.; Hung, H.

    2013-02-01

    Global emissions of mercury continue to change at the same time as the Arctic is experiencing ongoing climatic changes. Continuous monitoring of atmospheric mercury provides important information about long-term trends in the balance between transport, chemistry, and deposition of this pollutant in the Arctic atmosphere. Ten-year records of total gaseous mercury (TGM) from 2000 to 2009 were analyzed from two high Arctic sites at Alert (Nunavut, Canada) and Zeppelin Station (Svalbard, Norway); one sub-Arctic site at Kuujjuarapik (Nunavik, Québec, Canada); and three temperate Canadian sites at St. Anicet (Québec), Kejimkujik (Nova Scotia) and Egbert (Ontario). Five of the six sites examined showed a decreasing trend over this time period. Overall trend estimates at high latitude sites were: -0.9% yr-1 (95% confidence limits: -1.4, 0) at Alert and no trend (-0.5, +0.7) at Zeppelin Station. Faster decreases were observed at the remainder of the sites: -2.1% yr-1 (-3.1, -1.1) at Kuujjuarapik, -1.9% yr-1 (-2.1, -1.8) at St. Anicet, -1.6% yr-1 (-2.4, -1.0) at Kejimkujik and -2.2% yr-1 (-2.8, -1.7) at Egbert. Trends at the sub-Arctic and mid-latitude sites agree with reported decreases in background TGM concentration since 1996 at Mace Head, Ireland, and Cape Point, South Africa, but conflict with estimates showing an increase in global anthropogenic emissions over a similar period. Trends in TGM at the two high Arctic sites were not only less negative (or neutral) overall but much more variable by season. Possible reasons for differences in seasonal and overall trends at the Arctic sites compared to those at lower latitudes are discussed, as well as implications for the Arctic mercury cycle. The first calculations of multi-year trends in reactive gaseous mercury (RGM) and total particulate mercury (TPM) at Alert were also performed, indicating increases from 2002 to 2009 in both RGM and TPM in the spring when concentrations are highest.

  17. History of Sea Ice Changes in the Canadian Arctic and the Impact on Humans

    NASA Astrophysics Data System (ADS)

    Mudie, P. J.; Rochon, A.; Levac, E.

    2004-05-01

    The discontinuous chronology of archaeological records from the Canadian Arctic suggests that major climatic changes caused the abrupt abandonment of settlements and life style shifts in Paleo- and Neo-Eskimo societies. The centennial-scale resolution of previous paleoclimate reconstructions, however, does not permit detailed examination of this idea. Climate warming of more than 1.5C during the past 3 decades has caused reduction of sea ice and loss of marine mammals, forcing catastrophic changes on the Inuit people. Computer models forecast continued Arctic warming up to 4C but the 150-year database for the models covers only a fraction of the warm-cold cyclicity data in Holocene geological records. We therefore examine the decadal-scale paleoclimatic changes recorded by quantitative palynological data in a 6,500 year-long record from Coburg Polynya (Core LSSL 2001-006 75 35' N, 78 41'W) near the Palaeo- and Neo-Eskimo occupations of the North Devon Lowlands and in cores Hu 91-039-008 and 007 from the central North Water Polynya (NOW) between Ellesmere Island and Thule, Greenland (77 16.0'N, 74 19.9'W). Palaeotransfer function data from dinoflagellate cyst assemblages in the cores provide quantitative estimates of changes in sea surface temperature (SST) and sea ice cover (SIC) with the same accuracy as historical shipboard oceanographic measurements. Both sites record abrupt temperature changes of 2 - 4C that can be related to the archaeological record of major changes in hunting modes of Paleo- and Neo-Eskimo peoples and to detailed occupation-abandonment cycles on Devon and Ellesmere Islands. The paleoceanographic reconstructions show that from 6500 to 2600 BP, there were large oscillations in summer SST from 2-4C cooler than now to 6C warmer, and that annual variations in SIC ranged from 2 months more of heavy (more than 50 percent) ice to a 4-month extension of open water. This interval corresponds to the period of pre-Dorset Palaeo-Eskimo cultures that

  18. Cloud identification in the Canadian High Arctic using the UV-visible colour index

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoyi; Adams, Cristen; Strong, Kimberly; Duck, Thomas; Perro, Chris; Hudak, David; Rodriguez, Peter

    2014-05-01

    In UV-visible spectroscopy, Rayleigh and Mie scattering contribute to the broadband extinction seen in spectra of scattered sunlight. The relative intensity of these two components of scattering is highly dependent on the cloud condition of the sky. The colour index, defined as the ratio of light intensities at different wavelengths, typically 350 nm and 550 nm, provides a means of determining the cloud conditions. A UV-visible triple-grating spectrometer, the UT-GBS (University of Toronto Ground-Based Spectrometer), was installed at the Polar Environment Atmospheric Research Laboratory (PEARL), at Eureka in the Canadian High Arctic (86.4°W, 80.1°N) in 1999. Since then, the instrument has made daily measurements during spring from 1999-2009, and year-round, with the exception of polar night, from 2010-2013. The UT-GBS measures vertical column densities of ozone, NO2, and BrO, as well as slant column densities of enhanced OClO, by using the Differential Optical Absorption Spectroscopy (DOAS) technique. We use the colour index data from the UT-GBS to distinguish polar stratospheric clouds and tropospheric clouds. The UV-visible measurements are supplemented by vertically resolved lidar and radar cloud data products. The CANDAC (Canadian Network for the Detection of Atmospheric Change) Rayleigh-Mie-Raman Lidar (CRL) and the Millimetre Cloud Radar (MMCR) are located at the Zero Altitude PEARL Auxiliary Laboratory (0PAL), which is about 15 km away from PEARL. The CRL uses ultra-short pulses of light from two lasers, operating at ultraviolet (355 nm) and visible (532 nm) wavelengths. The CRL measures the vertical distribution of aerosols, temperature, and water vapour in the troposphere and lower stratosphere. The zenith-pointing MMCR measures equivalent radar reflectivity, Doppler velocity, spectral width, and Doppler spectra, from which information about cloud heights, thicknesses, internal structure and vertical motions can be determined. Polar stratospheric cloud

  19. Paleoeskimo Demographic History in the Canadian Arctic (ca. 4800-800 B.P.) and its Relationship to Mid-Late Holocene Climate Variability.

    NASA Astrophysics Data System (ADS)

    Savelle, J. M.

    2014-12-01

    Paleoeskimos were the first occupants of the central and eastern Canadian Arctic, spreading east from the Bering Strait region beginning approximately 4800 B.P., and occupied much of the Canadian Arctic through to their eventual disappearance ca. 800 B.P. Extensive regional archaeological site surveys throughout this area by the author and Arthur S. Dyke indicate that Paleoskimo populations underwent a series of population 'boom' (rapid expansion) and 'bust' (population declines and local extinctions) over the 4,000 year occupation history, including in the purported stable 'core area' of Foxe Basin. In this paper, we examine the contemporaneity of the local boom and bust cycles in a pan-Canadian Arctic context, and in turn examine the relationship of these cycles to mid-late Holocene climate variability.

  20. Landscape and hydrologic changes in the permafrost regions of the Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Marsh, P.

    2012-12-01

    The Western Canadian Arctic, in the vicinity of the Mackenzie River Delta, is characterized by long cold winters, short summers, low precipitation, thin organic soils, and ice-rich continuous permafrost. Over the last few decades, this region has undergone dramatic changes in climate, with warming air temperature and decreasing winter and summer precipitation. This has resulted in various landscape changes, including the warming of the upper layers of the permafrost, deepening of the active layer, drainage of permafrost affected lakes, an ongoing change from tundra to shrub tundra, and earlier spring breakup of streams, rivers and lakes. However, interactions between climate, hydrology, snow, and vegetation greatly affect both the spatial and temporal changes to the permafrost and hydrology of this region. Knowledge of these changes is important to the understanding of methane dynamics in this permafrost landscape, and for predicting future changes. Two examples of observed landscape change will be discussed. First, ground based observations and analysis of air photo images has demonstrated that shrub expansion is not uniform across the landscape, but instead is characterized by shrub patches of varying size. This patchiness is likely related to existing variations in soil temperature and moisture, active layer depth, snowcover, and tundra fires. As shrub patches further develop, they impact soil temperature and active layer depth. For example, small patches of shrubs typically have snow depths that are deeper than surrounding tundra areas due to the accumulation of blowing snow, and as a result have much warmer soil temperatures and deeper active layers. In contrast to these small shrub patches, large shrub patches have snow depths only slightly larger than found in the surrounding tundra and therefore only slightly warmer winter soil temperatures. However, shading of the surface during the summer may result in cooler summer soil temperatures. The overall effect

  1. Acceleration of thaw slump activity in glaciated landscapes of the Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Segal, Rebecca A.; Lantz, Trevor C.; Kokelj, Steven V.

    2016-03-01

    Climate change is increasing the frequency and intensity of thermokarst, but the influences of regional climate and physiography remain poorly understood. Retrogressive thaw slumping is one of the most dynamic forms of thermokarst and affects many areas of glaciated terrain across northwestern Canada. In this study, we used airphotos and satellite imagery to investigate the influence of climate and landscape factors on thaw slump dynamics. We assessed slump size, density, and growth rates in four regions of ice-rich terrain with contrasting climate and physiographic conditions: the Jesse Moraine, the Tuktoyaktuk Coastlands, the Bluenose Moraine, and the Peel Plateau. Observed increases in: (1) the area impacted by slumps (+2 to +407%), (2) average slump sizes (+0.31 to +1.82 ha), and (3) slump growth rates (+169 to +465 m2 yr-1) showed that thermokarst activity is rapidly accelerating in ice-rich morainal landscapes in the western Canadian Arctic, where slumping has become a dominant driver of geomorphic change. Differences in slump characteristics among regions indicate that slump development is strongly influenced by topography, ground ice conditions, and Quaternary history. Observed increases in slump activity occurred in conjunction with increases in air temperature and precipitation, but variation in slump activity among the four regions suggests that increased precipitation has been an important driver of change. Our observation that the most rapid intensification of slump activity occurred in the coldest environment (the Jesse Moraine on Banks Island) indicates that ice-cored landscapes in cold permafrost environments are highly vulnerable to climate change.

  2. Seasonal demography of a cyclic lemming population in the Canadian Arctic.

    PubMed

    Fauteux, Dominique; Gauthier, Gilles; Berteaux, Dominique

    2015-09-01

    1. The causes of cyclical fluctuations in animal populations remain a controversial topic in ecology. Food limitation and predation are two leading hypotheses to explain small mammal population dynamics in northern environments. We documented the seasonal timing of the decline phases and demographic parameters (survival and reproduction) associated with population changes in lemmings, allowing us to evaluate some predictions from these two hypotheses. 2. We studied the demography of brown lemmings (Lemmus trimucronatus), a species showing 3- to 4-year population cycles in the Canadian Arctic, by combining capture-mark-recapture analysis of summer live-trapping with monitoring of winter nests over a 10-year period. We also examined the effects of some weather variables on survival. 3. We found that population declines after a peak occurred between the summer and winter period and not during the winter. During the summer, population growth was driven by change in survival, but not in fecundity or proportion of juveniles, whereas in winter population growth was driven by changes in late summer and winter reproduction. 4. We did not find evidence for direct density dependence on summer demographic parameters, though our analysis was constrained by the paucity of data during the low phase. Body mass, however, was highest in peak years. 5. Weather effects were detected only in early summer when lemming survival was positively related to snow depth at the onset of melt but negatively related to rainfall. 6. Our results show that high mortality causes population declines of lemmings during summer and fall, which suggests that predation is sufficient to cause population crashes, whereas high winter fecundity is the primary factor leading to population irruptions. The positive association between snow depth and early summer survival may be due to the protective cover offered by snow against predators. It is still unclear why reproduction remains low during the low phase.

  3. Field Immune Assessment during Simulated Planetary Exploration in the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Crucian, Brian; Lee, Pascal; Stowe, Raymond; Jones, Jeff; Effenhauser, Rainer; Widen, Raymond; Sams, Clarence

    2006-01-01

    Dysregulation of the immune system has been shown to occur during space flight, although the detailed nature of the phenomenon and the clinical risks for exploration class missions has yet to be established. In addition, the growing clinical significance of immune system evaluation combined with epidemic infectious disease rates in third world countries provides a strong rationale for the development of field-compatible clinical immunology techniques and equipment. In July 2002 NASA performed a comprehensive field immunology assessment on crewmembers participating in the Haughton-Mars Project (HMP) on Devon Island in the high Canadian Arctic. The purpose of the study was to evaluate mission-associated effects on the human immune system, as well as to evaluate techniques developed for processing immune samples in remote field locations. Ten HMP-2002 participants volunteered for the study. A field protocol was developed at NASA-JSC for performing sample collection, blood staining/processing for immunophenotype analysis, wholeblood mitogenic culture for functional assessments and cell-sample preservation on-location at Devon Island. Specific assays included peripheral leukocyte distribution; constitutively activated T cells, intracellular cytokine profiles and plasma EBV viral antibody levels. Study timepoints were L-30, midmission and R+60. The protocol developed for immune sample processing in remote field locations functioned properly. Samples were processed in the field location, and stabilized for subsequent analysis at the Johnson Space Center in Houston. The data indicated that some phenotype, immune function and stress hormone changes occurred in the HMP field participants that were largely distinct from pre-mission baseline and post-mission recovery data. These immune changes appear similar to those observed in Astronauts following spaceflight. The sample processing protocol developed for this study may have applications for immune assessment during

  4. Intra-crater sedimentary deposits at the Haughton impact structure, Devon Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Osinski, Gordon R.; Lee, Pascal

    2005-12-01

    Detailed field mapping has revealed the presence of a series of intra-crater sedimentary deposits within the interior of the Haughton impact structure, Devon Island, Canadian High Arctic. Coarse-grained, well-sorted, pale gray lithic sandstones (reworked impact melt breccias) unconformably overlie pristine impact melt breccias and attest to an episode of erosion, during which time significant quantities of impact melt breccias were removed. The reworked impact melt breccias are, in turn, unconformably overlain by paleolacustrine sediments of the Miocene Haughton Formation. Sediments of the Haughton Formation were clearly derived from pre-impact lower Paleozoic target rocks of the Allen Bay Formation, which form the crater rim in the northern, western, and southern regions of the Haughton structure. Collectively, these field relationships indicate that the Haughton Formation was deposited up to several million years after the formation of the Haughton crater and that they do not, therefore, represent an immediate, post-impact crater lake deposit. This is consistent with new isotopic dating of impactites from Haughton that indicate an Eocene age for the impact event (Sherlock et al. 2005). In addition, isolated deposits of post-Miocene intra-crater glacigenic and fluvioglacial sediments were found lying unconformably over remnants of the Haughton Formation, impact melt breccias, and other pre-impact target rock formations. These deposits provide clear evidence for glaciation at the Haughton crater. The wealth and complexity of geological and climatological information preserved as intra-crater deposits at Haughton suggests that craters on Mars with intra-crater sedimentary records might present us with similar opportunities, but also possibly significant challenges.

  5. Temporal trends of mercury in eggs of five sympatrically breeding seabird species in the Canadian Arctic.

    PubMed

    Braune, Birgit M; Gaston, Anthony J; Mallory, Mark L

    2016-07-01

    We compared temporal trends of total mercury (Hg) in eggs of five seabird species breeding at Prince Leopold Island in the Canadian high Arctic. As changes in trophic position over time have the potential to influence contaminant temporal trends, Hg concentrations were adjusted for trophic position (measured as δ(15)N). Adjusted Hg concentrations in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) increased from 1975 to the 1990s, followed by a plateauing of levels from the 1990s to 2014. Trends of adjusted Hg concentrations in eggs of murres, fulmars, black guillemots (Cepphus grylle) and black-legged kittiwakes (Rissa tridactyla) had negative slopes between 1993 and 2013. Adjusted Hg concentrations in glaucous gull (Larus hyperboreus) eggs decreased by 50% from 1993 to 2003 before starting to increase again. Glaucous gull eggs had the highest Hg concentrations followed by black guillemot eggs, and black-legged kittiwake eggs had the lowest concentrations consistently in the five years compared between 1993 and 2013. Based on published toxicological thresholds for Hg in eggs, there is little concern for adverse reproductive effects due to Hg exposure in these birds, although the levels in glaucous gull eggs warrant future scrutiny given the increase in Hg concentrations observed in recent years. There is evidence that the Hg trends observed reflect changing anthropogenic Hg emissions. It remains unclear, however, to what extent exposure to Hg on the overwintering grounds influences the Hg trends observed in the seabird eggs at Prince Leopold Island. Future research should focus on determining the extent to which Hg exposure on the breeding grounds versus the overwintering areas contribute to the trends observed in the eggs. PMID:27074200

  6. Climate change: Numerical modelling of sedimentation and coastal processes, eastern Canadian Arctic

    SciTech Connect

    Syvitski, J.P.M. ); Andrews, J.T. )

    1994-08-01

    We use three sequential [open quotes]water-sediment transport[close quotes] numerical models to evaluate changes in fluvial sediment outputs for two near-future contrasting climate-change scenarios (warmer summers or warmer and moister winters) for the eastern Canadian Arctic. Our integrated model generates values for deposition into a fiord basin. The effects of climate warming are imposed on 200-yr fluctuations in relative sea level (base level) that in turn have a long-term forcing associated with late Quaternary glacial unloading. Thus some areas are submerging (around the periphery of the former ice sheet) and others are emerging (inland at the heads of fiords). Small, short-term changes in sea level may involve meltwater supply to the world ocean from the melting of glaciers and ice sheets, and sea water expansion with a warming ocean. Alternatively, large ice sheets may also thicken over the short term (200 yr), thereby withdrawing water from the global hydrological cycle. Both climate scenarios result in an increased sediment flux over the next 200 yr. However, warmer summers will have the largest impact by (1) causing ice caps to melt, (2) inducing more expansive and turbid river plumes, (3) increasing progradation of the coastline into the sea, (4) raising relative sea level, and by (5) increasing the number and size of turbidity currents generated off river mouths. Warmer and moister winters that may lead to deviations from these impacts include (1) growth of ice caps, (2) fall of relative sea level, (3) stability of coastlines as increased sediment delivery keeps pace with changes in regional relative sea level, and (4) fewer basin turbidity currents, as more of the bedload is trapped on top of sandur surfaces. 55 refs., 11 figs., 2 tabs.

  7. Fast carnivores and slow herbivores: differential foraging strategies among grizzly bears in the Canadian Arctic.

    PubMed

    Edwards, Mark A; Derocher, Andrew E; Hobson, Keith A; Branigan, Marsha; Nagy, John A

    2011-04-01

    Categorizing animal populations by diet can mask important intrapopulation variation, which is crucial to understanding a species' trophic niche width. To test hypotheses related to intrapopulation variation in foraging or the presence of diet specialization, we conducted stable isotope analysis (δ(13)C, δ(15)N) on hair and claw samples from 51 grizzly bears (Ursus arctos) collected from 2003 to 2006 in the Mackenzie Delta region of the Canadian Arctic. We examined within-population differences in the foraging patterns of males and females and the relationship between trophic position (derived from δ(15)N measurements) and individual movement. The range of δ(15)N values in hair and claw (2.0-11.0‰) suggested a wide niche width and cluster analyses indicated the presence of three foraging groups within the population, ranging from near-complete herbivory to near-complete carnivory. We found no linear relationship between home range size and trophic position when the data were continuous or when grouped by foraging behavior. However, the movement rate of females increased linearly with trophic position. We used multisource dual-isotope mixing models to determine the relative contributions of seven prey sources within each foraging group for both males and females. The mean bear dietary endpoint across all foraging groups for each sex fell toward the center of the mixing polygon, which suggested relatively well-mixed diets. The primary dietary difference across foraging groups was the proportional contribution of herbaceous foods, which decreased for both males and females from 42-76 to 0-27% and 62-81 to 0-44%, respectively. Grizzlies of the Mackenzie Delta live in extremely harsh conditions and identifying within-population diet specialization has improved our understanding of varying habitat requirements within the population.

  8. Fast carnivores and slow herbivores: differential foraging strategies among grizzly bears in the Canadian Arctic.

    PubMed

    Edwards, Mark A; Derocher, Andrew E; Hobson, Keith A; Branigan, Marsha; Nagy, John A

    2011-04-01

    Categorizing animal populations by diet can mask important intrapopulation variation, which is crucial to understanding a species' trophic niche width. To test hypotheses related to intrapopulation variation in foraging or the presence of diet specialization, we conducted stable isotope analysis (δ(13)C, δ(15)N) on hair and claw samples from 51 grizzly bears (Ursus arctos) collected from 2003 to 2006 in the Mackenzie Delta region of the Canadian Arctic. We examined within-population differences in the foraging patterns of males and females and the relationship between trophic position (derived from δ(15)N measurements) and individual movement. The range of δ(15)N values in hair and claw (2.0-11.0‰) suggested a wide niche width and cluster analyses indicated the presence of three foraging groups within the population, ranging from near-complete herbivory to near-complete carnivory. We found no linear relationship between home range size and trophic position when the data were continuous or when grouped by foraging behavior. However, the movement rate of females increased linearly with trophic position. We used multisource dual-isotope mixing models to determine the relative contributions of seven prey sources within each foraging group for both males and females. The mean bear dietary endpoint across all foraging groups for each sex fell toward the center of the mixing polygon, which suggested relatively well-mixed diets. The primary dietary difference across foraging groups was the proportional contribution of herbaceous foods, which decreased for both males and females from 42-76 to 0-27% and 62-81 to 0-44%, respectively. Grizzlies of the Mackenzie Delta live in extremely harsh conditions and identifying within-population diet specialization has improved our understanding of varying habitat requirements within the population. PMID:21153738

  9. Spatial and Temporal Changes in the Number, and Area, of Permafrost Controlled Lakes in the Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Marsh, P.; Pohl, S.; Onclin, C.; Russell, M.

    2006-12-01

    Previous studies have considered lake formation and drainage in the continuous permafrost areas of the Western Canadian Arctic (Mackay, 1990; Marsh et al., 2003), and "disappearing arctic lakes" in Siberia (Smith et al., 2005). Smith et al. (2005) suggested that "the ultimate effect of continued climate warming on high- latitude, permafrost-controlled lakes and wetlands may well be their widespread disappearance". Given the vast number of permafrost controlled lakes in many Arctic regions, these studies raise the concern that climate change will have significant impacts on these lakes, with many lakes disappearing from the landscape, and with significant implications to arctic hydrology and ecology. This paper will discuss changes in both the area and number of permafrost dominated lakes in the Mackenzie Delta region of the Canadian Western Arctic. Like many arctic regions, the Western Canadian Arctic has a vast number of lakes and ponds. These permafrost dominated lakes developed due to a complex interaction of climate, permafrost, and hydrology. Although it is well known that climate warming may (a) increase the size, and number, of lakes due to thermokarst processes, as well as (b) decrease the number of lakes due to lake drainage, the relative importance of each process is not well known and therefore the impact of climate change on permafrost dominated lakes is unknown. The sensitivity of these processes, and complex interaction with climate, is demonstrated by the process of rapid lake drainage. Such drainage is common in the Mackenzie Delta region, and occurs when lakes melt new drainage channels through ice rich permafrost, resulting in the complete, or partial, drainage of the lake in a few hours. The effect of climate change on rapid lake drainage is controlled by a number of processes, with each having a different response to changes in climate. For example: (i) warmer and snowier winters typically result in decreased ice wedge cracking and therefore

  10. The Economic and Social Impact of the Arctic Co-operative Movement on the Canadian Eskimo.

    ERIC Educational Resources Information Center

    Jensen, Kenneth D.

    Canada's Arctic co-operatives are designed to provide a means of encouraging Eskimos to participate directly in the economic development of the Arctic through the promotion of cooperative ownership and enterprise. They also seek to provide a method of maximizing economic returns in Arctic communities from local businesses and enterprise. Backed by…

  11. Persistent organic pollutant and mercury concentrations in eggs of ground-nesting marine birds in the Canadian high Arctic.

    PubMed

    Peck, Liam E; Gilchrist, H Grant; Mallory, Conor D; Braune, Birgit M; Mallory, Mark L

    2016-06-15

    We collected eggs of eight marine bird species from several colony sites in the Canadian high Arctic located at approximately 76°N and analyzed them for concentrations of legacy persistent organic pollutants (POPs) and mercury. We provide the first report on concentrations of POPs in eggs of three Arctic species (Thayer's gull Larus thayeri, Sabine's gull Xema sabini, Ross's Gull Rhodostethia rosea), and we found significant differences in each of the POP profiles among the five species with sufficient data for statistical comparisons (Thayer's gull, black guillemot Cepphus grylle, Sabine's gull, Arctic tern Sterna paradisaea and common eider Somateria mollissima borealis). The Ross's Gull had unexpectedly high POP concentrations relative to the other species examined, although this was based on a single egg, while glaucous gull Larus hyperboreus eggs from our sampling location had very low POPs. Sabine's gulls had the lowest Hg of the eggs studied, consistent with their low trophic position, but concentrations of their legacy POPs were higher than expected. We also noted that total hexachlorocyclohexanes were higher than reported elsewhere in the circumpolar Arctic in three species. PMID:26971212

  12. Polar Gas to pick route for Arctic Y Line

    SciTech Connect

    Not Available

    1980-05-26

    Polar Gas Project is considering four possible Y line routes to move gas reserves from the Arctic Islands and the MacKenzie Delta/Beaufort Sea areas to southern Canada. All four routes are west of the single line route proposed by Polar Gas Ltd. in 1977 to run from the Arctic Islands to Longlac, Ontario, and would connect with existing pipelines at either Longlac, Winnipeg, Calgary, or Edmonton. Marketable reserves in the High Arctic Islands are estimated at 12.7 trillion cubic feet, not counting 3-6 trillion cubic feet probably contained in recent discoveries; the MacKenzie Delta reserves are estimated at 5.8 trillion cubic feet. The gas will be chilled to 0C for passage through permafrost regions, to prevent thawing of the soil, but the gas will be at higher temperatures in other areas, with various construction techniques used to protect the area of discontinuous permafrost from thawing. More than $70 million has been spent on project studies. An application will be filed in 1981, and the pipeline could be completed in 7-10 years.

  13. DNA Barcoding the Canadian Arctic Flora: Core Plastid Barcodes (rbcL + matK) for 490 Vascular Plant Species

    PubMed Central

    Saarela, Jeffery M.; Sokoloff, Paul C.; Gillespie, Lynn J.; Consaul, Laurie L.; Bull, Roger D.

    2013-01-01

    Accurate identification of Arctic plant species is critical for understanding potential climate-induced changes in their diversity and distributions. To facilitate rapid identification we generated DNA barcodes for the core plastid barcode loci (rbcL and matK) for 490 vascular plant species, representing nearly half of the Canadian Arctic flora and 93% of the flora of the Canadian Arctic Archipelago. Sequence recovery was higher for rbcL than matK (93% and 81%), and rbcL was easier to recover than matK from herbarium specimens (92% and 77%). Distance-based and sequence-similarity analyses of combined rbcL + matK data discriminate 97% of genera, 56% of species, and 7% of infraspecific taxa. There is a significant negative correlation between the number of species sampled per genus and the percent species resolution per genus. We characterize barcode variation in detail in the ten largest genera sampled (Carex, Draba, Festuca, Pedicularis, Poa, Potentilla, Puccinellia, Ranunculus, Salix, and Saxifraga) in the context of their phylogenetic relationships and taxonomy. Discrimination with the core barcode loci in these genera ranges from 0% in Salix to 85% in Carex. Haplotype variation in multiple genera does not correspond to species boundaries, including Taraxacum, in which the distribution of plastid haplotypes among Arctic species is consistent with plastid variation documented in non-Arctic species. Introgression of Poa glauca plastid DNA into multiple individuals of P. hartzii is problematic for identification of these species with DNA barcodes. Of three supplementary barcode loci (psbA–trnH, psbK–psbI, atpF–atpH) collected for a subset of Poa and Puccinellia species, only atpF–atpH improved discrimination in Puccinellia, compared with rbcL and matK. Variation in matK in Vaccinium uliginosum and rbcL in Saxifraga oppositifolia corresponds to variation in other loci used to characterize the phylogeographic histories of these Arctic-alpine species. PMID

  14. Environmental controls on the 2H/1H values of terrestrial leaf waxes in the eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Shanahan, Timothy M.; Hughen, Konrad A.; Ampel, Linda; Sauer, Peter E.; Fornace, Kyrstin

    2013-10-01

    The hydrogen isotope composition of plant waxes preserved in lacustrine sediments is a potentially valuable tool for reconstructing paleoenvironmental changes in the Arctic. However, in contrast to the mid- and low-latitudes, significantly less effort has been directed towards understanding the factors controlling D/H fractionation in high latitude plant waxes and the impact of these processes on the interpretation of sedimentary leaf wax δD records. To better understand these processes, we examined the D/H ratios of long chain fatty acids in lake surface sediments spanning a temperature and precipitation gradient on Baffin Island in the eastern Canadian Arctic. D/H ratios of plant waxes increase with increasing temperature and aridity, with values ranging from -240‰ to -160‰ over the study area. Apparent fractionation factors between n-alkanoic acids in Arctic lake sediments and precipitation(εFA-ppt) are less negative than those of mid-latitude lakes and modern plants by 25‰ to 65‰, consistent with n-alkane data from modern Arctic plants (Yang et al., 2011). Furthermore, εFA-ppt values from Arctic lakes become systematically more positive with increasing evaporation, in contrast to mid-latitude sites, which show little to no change in fractionation with aridity. These data are consistent with enhanced water loss and isotope fractionation at higher latitude in the Arctic summer, when continuous sunlight supports increased daily photosynthesis. The dominant control on δDFA variations on Baffin Island is temperature. However, changing εFA-ppt result in steeper δDFA-temperature relationships than observed for modern precipitation. The application of this δDFA-based paleotemperature calibration to existing δDFA records from Baffin Island produces much more realistic changes in late Holocene temperature and highlights the importance of these effects in influencing the interpretation of Arctic δDFA records. A better understanding of the controls on

  15. Heavy metal bioaccumulation and histopathological alterations in wild Arctic hares (Lepus arcticus) inhabiting a former lead-zinc mine in the Canadian high Arctic: A preliminary study.

    PubMed

    Amuno, S; Niyogi, S; Amuno, M; Attitaq, J

    2016-06-15

    A preliminary study was undertaken to determine post-mining baseline accumulation of selected trace metals, and histopathological alterations in free-living arctic hares (Lepus arcticus) inhabiting the vicinity of a former lead-zinc mine located on North Baffin Island in the Canadian High Arctic. Trace metal analysis included measurement of As, Cd, Fe, Pb and Zn in tissues, and histopathological assessment comprised of evaluation and scoring the severity of metal-induced hepatic and renal lesions. Metal contents in hepatic and renal tissues from hares from the mine area compared with the reference locations did not differ significantly suggesting that the animals are not uniformly exposed to background levels of metals in the environment. However, relatively higher accumulation pattern of Pb and Cd were noted in liver tissues of hare from the mine area compared to the background area, but did not induce increased lesions. Surface soils near the mine area contained relatively higher levels of trace metals (Zn>Mn>Pb>Cd>As) compared to reference soils, and with soil levels of Cd showing strong correlation with Cd accumulation in kidney tissues. Generally, both case and reference animals showed similar but varying severities of hepatic and renal lesions at the sublethal level, notably vascular congestion, occasional large hepatocyte nuclei, binucleate hepatocytes, yellow-brown pigmentation in the cytoplasm of hepatocytes and clustering of lymphocytes. Only hares with relatively higher accumulation of Pb from the mine area showed evidence of renal edema and hemorrhage of the capsular surface. This study constitutes the first assessment of metal induced histopathological alterations in arctic hares exposed to a historical mining area in the high arctic. PMID:26974573

  16. Assessing diet and lifestyle in the Canadian Arctic Inuit and Inuvialuit to inform a nutrition and physical activity intervention programme.

    PubMed

    Sharma, S

    2010-10-01

    Inuit in Nunavut (NU) and Inuvialuit in the Northwest Territories (NWT), Canada, were traditionally nomadic peoples whose culture and lifestyle were founded on hunting and gathering foods from the local environment, primarily land and marine mammals. Lifestyle changes within the last century have brought about a rapid nutrition transition, characterised by decreasing consumption of traditional foods and an associated increase in the consumption of processed, shop-bought foods. This transition may be attributed to a multitude of factors, such as acculturation, overall food access and availability, food insecurity and climate change. Obesity and risk for chronic disease are higher in the Canadian Arctic population compared with the Canadian national average. This present review describes the study population and methodologies used to collect data in order to study the nutrition transition amongst Aboriginal Arctic populations and develop Healthy Foods North (HFN), a novel, multi-institutional and culturally appropriate programme that aims to improve dietary adequacy and reduce risk of chronic disease. Included in this special issue of the Journal of Human Nutrition and Dietetics are papers describing dietary intake patterns, physical activity levels, dietary behaviours, chronic disease prevalence and psychosocial factors that potentially mediate behaviour. A further paper describes how these data were utilised to inform and develop Healthy Foods North.

  17. The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): NmF2 and hmF2 specification

    NASA Astrophysics Data System (ADS)

    Themens, David; Jayachandran, Thayyil

    2016-07-01

    It is well known that the IRI suffers reduced accuracy in its representation of monthly median ionospheric variability at high latitudes (Themens et al. 2014, Themens et al. 2016). These inaccuracies are believed to stem from a historical lack of data from these regions. Now, roughly thirty and forty years after the development of the original URSI and CCIR foF2 maps, respectively, there exists a much larger dataset of high latitude observations of ionospheric electron density. These new measurements come in the form of new ionosonde deployments, such as those of the Canadian High Arctic Ionospheric Network, the CHAMP, GRACE, and COSMIC radio occultation missions, and the construction of the Poker Flat, Resolute, and EISCAT Incoherent Scatter Radars systems. These new datasets afford an opportunity to revise the IRI's representation of the high latitude ionosphere. For this purpose, we here introduce the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM), which will incorporate all of the above datasets, as well as the older observation records, into a new climatological representation of the high latitude ionosphere. In this presentation, we introduce the NmF2 and hmF2 portions of the model and present a validation of the new model with respect to ionosonde observations in Alert, Canada. A comparison with respect to IRI performance will also be presented.

  18. Developing a water clear of sea ice algorithm over Canadian Arctic sea ice from QuikSCAT and AMSR-E measurements

    NASA Astrophysics Data System (ADS)

    Howell, S.; Derksen, C.

    2009-12-01

    The detection of sea ice phenological events (melt onset or freeze onset) is important for understanding both regional and global climate processes. Sea ice phonological events are associated with meaningful changes in shortwave albedo and have also been shown to be sensitive indicators of climate variability and change. The break-up period, which defines the period between melt onset and complete disappearance of ice (i.e. water clear of ice) however, has received considerably less attention. This period is important because the loss of summer sea ice attributed to an increase in the length of open water season has ultimately driven increases in autumn surface air temperatures over the Arctic. Understanding water clear of sea ice variability is also particularly important within Canadian Arctic waters because of several major shipping routes such as the Arctic Bridge through Hudson Bay and the Northwest Passage through the Canadian Arctic Archipelago. We make use of enhanced QuikSCAT and AMSR-E measurements to develop a water clear of sea ice algorithm for application within Canadian Arctic waters. The Canadian Ice Service Digital Archive (CISDA) was used to validate water clear of sea ice estimates. Water clear of sea ice maps were created (1) using the backscatter coefficient from QuikSCAT, (2) AMSR-E brightness temperatures (6, 18 and 36 GHz), and (3) blending the backscatter coefficient with brightness temperatures in order to understand how estimates vary between sensors. Results show that algorithms developed solely using the backscatter coefficient from QuikSCAT or AMSR-E brightness temperatures at 6 and 18 GHz are useful for monitoring water clear of sea ice however, each measure suffers some limitations and sensitivities (e.g. coarse spatial resolution, transient weather conditions inducing false detection, and atmospheric interference). The blended algorithm using both QuikSCAT and AMSR-E brightness temperatures (6 and 18 GHz) provided the most

  19. Undiscovered Arctic gas hydrates: permafrost relationship and resource evaluation.

    NASA Astrophysics Data System (ADS)

    Cherkashov, G. A.; Matveeva, T.

    2011-12-01

    Though ice-core studies show that multidecadal-scale methane variability is only weakly correlated with reconstructed temperature variations (Mitchell et al., 2010) methane emission to the atmosphere still consider as the most significant contributions to the global warming processes. Pockmarks, seeps, mud volcanoes and other features associated with methane fluxes from the seabed have been widely reported, particularly during the last three decades. On continental margins, seepage of hydrocarbon gases from shallow sedimentary layers is a common phenomenon, resulting either from in situ formation of gases (mainly methane) by bacterial decomposition of organic matter within rapidly accumulated upper sediments or from upward migration of gases formed at greater depths. Furthermore, processes associated with seabed fluid flow have been shown to affect benthic ecology and to supply methane to the hydrosphere and the atmosphere (Judd, 2003; Hovland and Judd, 2007). The most recent investigations testified that revaluation of the role of gas seeps and related gas hydrate formation processes in the Arctic environment is necessary for the understanding of global methane balance and global climate changes (Westbrook et al., 2009; Shahova and Semiletov, 2010). With respect to gas hydrate formation, due to the presence of relict permafrost the Arctic submarine environment holds a specific place that is distinct from the rest of the Ocean. Submarine gas hydrates in the Arctic may be confined to (1) relict permafrost occurrences on the shelf; (2) concentrated methane infiltration toward the seafloor (shallow-seated gas hydrates); (3) dissipated methane infiltration from great depths (deep-seated gas hydrates). Permafrost-related or cryogenic gas hydrates form due to exogenous cooling of sediment (intra- and sub-permafrost gas hydrates). It is also suggested that some parts of hydrates may be preserved owing to a self-preservation effect above the gas hydrate stability zone

  20. Plasma phospholipid fatty acids in the central Canadian arctic: biocultural explanations for ethnic differences.

    PubMed

    Young, T K; Gerrard, J M; O'Neil, J D

    1999-05-01

    As part of the Keewatin Health Assessment Study, a comprehensive health interview and examination survey of Inuit and non-Inuit in the central Canadian Arctic during 1990-91, plasma samples were analyzed for phospholipid fatty acid composition. Compared to non-Inuit, the Inuit have reduced levels of dihomo-gamma-linoleic (DGLA) and arachidonic acid (ratios of 0.41 and 0.46) and the sum of all n-6 fatty acids (ratio of 0.65), but increased level of eicosapentaenoic (EPA) acid (ratio of 1.37). These trends are consistent with those reported from other circumpolar Inuit populations, especially the reduced arachidonic acid and increased EPA, although the Inuit excess in EPA is much less pronounced due to the greater importance of caribou rather than sea mammals in most of the Keewatin communities. The high linoleic/arachidonic acid ratio suggests increased inhibition of the metabolic pathway regulated by the enzyme delta-5 desaturase, which can be explained by the presence of high levels of highly unsaturated fatty acids of dietary origin, and/or a genetic deficiency. In multiple linear regression models with the independent variable list consisting of Inuit status, age, sex, education, physical activity, spending time on the land and consumption of wild meat and local fish, Inuit status is independently associated with lower levels of the n-6 acids but not the n-3 acids. This indicates that factors other than diet and lifestyle, perhaps genetic ones, may account for the observed "ethnic" differences. However, for those fatty acids in which Inuit differ from non-Inuit, there is no dose-response relationship in terms of self-reported degree ofnon-Inuit admixture. Dietary fatty acids play an important role in the risk of cardiovascular diseases and diabetes, diseases of increasing importance in the health transition experienced by the Inuit. Association studies of plasma fatty acids and DNA markers of candidate genes for atherosclerosis and insulin resistance may provide

  1. Household Crowding and Food Insecurity Among Inuit Families With School-Aged Children in the Canadian Arctic

    PubMed Central

    Muckle, Gina; Dewailly, Éric; Jacobson, Joseph L.; Jacobson, Sandra W.; Ayotte, Pierre; Riva, Mylène

    2015-01-01

    Objectives. We examined the relation of household crowding to food insecurity among Inuit families with school-aged children in Arctic Quebec. Methods. We analyzed data collected between October 2005 and February 2010 from 292 primary caregiver–child dyads from 14 Inuit communities. We collected information about household conditions, food security, and family socioeconomic characteristics by interviews. We used logistic regression models to examine the association between household crowding and food insecurity. Results. Nearly 62% of Inuit families in the Canadian Arctic resided in more crowded households, placing them at risk for food insecurity. About 27% of the families reported reducing the size of their children’s meals because of lack of money. The likelihood of reducing the size of children’s meals was greater in crowded households (odds ratio = 3.73; 95% confidence interval = 1.96, 7.12). After we adjusted for different socioeconomic characteristics, results remained statistically significant. Conclusions. Interventions operating across different levels (community, regional, national) are needed to ensure food security in the region. Targeting families living in crowded conditions as part of social and public health policies aiming to reduce food insecurity in the Arctic could be beneficial. PMID:25602890

  2. Subglacial bedform evidence for a major palaeo-ice stream and its retreat phases in Amundsen Gulf, Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Stokes, C. R.; Clark, C. D.; Winsborrow, M. C. M.

    2006-05-01

    Ascertaining the location of palaeo-ice streams is crucial in order to produce accurate reconstructions of palaeo-ice sheets and examine interactions with the ocean-climate system. This paper reports evidence for a major ice stream in Amundsen Gulf, Canadian Arctic Archipelago. Mapping from satellite imagery (Landsat ETM+) and digital elevation models, including bathymetric data, is used to reconstruct flow-patterns on southwestern Victoria Island and the adjacent mainland (Nunavut and Northwest Territories). Several flow-sets indicative of ice streaming are found feeding into the marine trough and cross-cutting relationships between these flow-sets (and utilising previously published radiocarbon dates) reveal several phases of ice stream activity centred in Amundsen Gulf and Dolphin and Union Strait. A large erosional footprint on the continental shelf indicates that the ice stream (ca. 1000 km long and ca. 150 km wide) filled Amundsen Gulf, probably at the Last Glacial Maximum. Subsequent to this, the ice stream reorganised as the margin retreated back along the marine trough, eventually splitting into two separate low-gradient lobes in Prince Albert Sound and Dolphin and Union Strait. The location of this major ice stream holds important implications for ice sheet-ocean interactions and specifically, the development of Arctic Ocean ice shelves and the delivery of icebergs into the western Arctic Ocean during the late Pleistocene. Copyright

  3. A Community-Based, Environmental Chronic Disease Prevention Intervention to Improve Healthy Eating Psychosocial Factors and Behaviors in Indigenous Populations in the Canadian Arctic

    ERIC Educational Resources Information Center

    Mead, Erin L.; Gittelsohn, Joel; Roache, Cindy; Corriveau, André; Sharma, Sangita

    2013-01-01

    Diet-related chronic diseases are highly prevalent among indigenous populations in the Canadian Arctic. A community-based, multi-institutional nutritional and lifestyle intervention--Healthy Foods North--was implemented to improve food-related psychosocial factors and behaviors among Inuit and Inuvialuit in four intervention communities (with two…

  4. Review of technology for Arctic offshore oil and gas recovery. Appendices

    SciTech Connect

    Sackinger, W. M.

    1980-06-06

    This volume contains appendices of the following: US Geological Survey Arctic operating orders, 1979; Det Noske Vertas', rules for the design, construction and inspection of offshore technology, 1977; Alaska Oil and Gas Association, industry research projects, March 1980; Arctic Petroleum Operator's Association, industry research projects, January 1980; selected additional Arctic offshore bibliography on sea ice, icebreakers, Arctic seafloor conditions, ice-structures, frost heave and structure icing.

  5. Review of technology for Arctic offshore oil and gas recovery

    SciTech Connect

    Sackinger, W. M.

    1980-08-01

    The technical background briefing report is the first step in the preparation of a plan for engineering research oriented toward Arctic offshore oil and gas recovery. A five-year leasing schedule for the ice-prone waters of the Arctic offshore is presented, which also shows the projected dates of the lease sale for each area. The estimated peak production rates for these areas are given. There is considerable uncertainty for all these production estimates, since no exploratory drilling has yet taken place. A flow chart is presented which relates the special Arctic factors, such as ice and permafrost, to the normal petroleum production sequence. Some highlights from the chart and from the technical review are: (1) in many Arctic offshore locations the movement of sea ice causes major lateral forces on offshore structures, which are much greater than wave forces; (2) spray ice buildup on structures, ships and aircraft will be considerable, and must be prevented or accommodated with special designs; (3) the time available for summer exploratory drilling, and for deployment of permanent production structures, is limited by the return of the pack ice. This time may be extended by ice-breaking vessels in some cases; (4) during production, icebreaking workboats will service the offshore platforms in most areas throughout the year; (5) transportation of petroleum by icebreaking tankers from offshore tanker loading points is a highly probable situation, except in the Alaskan Beaufort; and (6) Arctic pipelines must contend with permafrost, making instrumentation necessary to detect subtle changes of the pipe before rupture occurs.

  6. Large-scale temperature and salinity changes in the upper Canadian Basin of the Arctic Ocean at a time of a drastic Arctic Oscillation inversion

    NASA Astrophysics Data System (ADS)

    Bourgain, P.; Gascard, J. C.; Shi, J.; Zhao, J.

    2013-04-01

    Between 2008 and 2010, the Arctic Oscillation index over Arctic regions shifted from positive values corresponding to more cyclonic conditions prevailing during the 4th International Polar Year (IPY) period (2007-2008) to extremely negative values corresponding to strong anticyclonic conditions in 2010. In this context, we investigated the recent large-scale evolution of the upper western Arctic Ocean, based on temperature and salinity summertime observations collected during icebreaker campaigns and from ice-tethered profilers (ITPs) drifting across the region in 2008 and 2010. Particularly, we focused on (1) the freshwater content which was extensively studied during previous years, (2) the near-surface temperature maximum due to incoming solar radiation, and (3) the water masses advected from the Pacific Ocean into the Arctic Ocean. The observations revealed a freshwater content change in the Canadian Basin during this time period. South of 80° N, the freshwater content increased, while north of 80° N, less freshening occurred in 2010 compared to 2008. This was more likely due to the strong anticyclonicity characteristic of a low AO index mode that enhanced both a wind-generated Ekman pumping in the Beaufort Gyre and a possible diversion of the Siberian River runoff toward the Eurasian Basin at the same time. The near-surface temperature maximum due to incoming solar radiation was almost 1 °C colder in the southern Canada Basin (south of 75° N) in 2010 compared to 2008, which contrasted with the positive trend observed during previous years. This was more likely due to higher summer sea ice concentration in 2010 compared to 2008 in that region, and surface albedo feedback reflecting more sun radiation back in space. The Pacific water (PaW) was also subjected to strong spatial and temporal variability between 2008 and 2010. In the Canada Basin, both summer and winter PaW signatures were stronger between 75° N and 80° N. This was more likely due to a strong

  7. The Canadian Arctic Archipelago throughflow in a multiresolution global model: Model assessment and the driving mechanism of interannual variability

    NASA Astrophysics Data System (ADS)

    Wekerle, Claudia; Wang, Qiang; Danilov, Sergey; Jung, Thomas; Schröter, Jens

    2013-09-01

    The volume and freshwater transports through the Canadian Arctic Archipelago (CAA) are assessed using the unstructured-mesh Finite Element Sea ice-Ocean Model (FESOM) in a global setup with the CAA resolved at 5 km scale. The hindcast simulation realistically represents fluxes through the main gates of the Arctic Ocean and the Arctic sea ice conditions. During the period 1968-2007, the mean volume transports through Lancaster Sound and Nares Strait amount to 0.86 and 0.91 Sv, respectively. The monthly mean volume transport through western Lancaster Sound is highly correlated with the observational estimate (r = 0.81). The seasonal variability of the Lancaster Sound transport is well represented in the model. The simulated mean CAA freshwater export rate is 123 mSv, slightly higher than the observational estimate. The interannual variability of CAA volume transports is determined by sea surface height (SSH) gradients between the Arctic Ocean and northern Baffin Bay. The sea level upstream of Lancaster Sound is mainly determined by that along the Beaufort Sea coast, which can be explained by changes in the wind regimes (cyclonic versus anticyclonic) associated with release or accumulation of freshwater in the Beaufort Gyre. Sea level variations downstream of Lancaster Sound and Nares Strait are connected to SSH variations in the eastern Baffin Bay and in the Labrador Sea, which can be attributed to the variability of ocean-atmosphere heat fluxes. Both processes upstream and downstream of the CAA are linked with the North Atlantic Oscillation type of atmospheric variability. The local mesh refinement of ˜5 km allows us to investigate the contribution of individual narrow straits to the Parry Channel volume transport. The volume transports through these straits show a very similar variability.

  8. Hydrological modelling of Toxoplasma gondii oocysts transport to investigate contaminated snowmelt runoff as a potential source of infection for marine mammals in the Canadian Arctic.

    PubMed

    Simon, Audrey; Rousseau, Alain N; Savary, Stéphane; Bigras-Poulin, Michel; Ogden, Nicholas H

    2013-09-30

    Toxoplasma gondii (T. gondii) is a zoonotic protozoan that sometimes causes serious illness in humans and other animals worldwide, including the Canadian Arctic. Wild and domestic felids, the only hosts able to shed T. gondii oocysts, are practically non-existent in the Canadian Arctic. So here the hypothesis that T. gondii oocysts, shed in the southern areas of the boreal watershed, could contaminate the Arctic coastal marine environment via surface runoff, particularly during the spring snowmelt period, was explored. A watershed model was applied to simulate the hydrological transport of T. gondii oocysts during the snowmelt period and test the possible efficiency of river-to-sea transport as a potential source of marine organisms' exposure to this pathogen. Simulations were run for two pilot watersheds with the ultimate aim of extrapolating the results across the Canadian Arctic watersheds. Results suggest that daily stream flow concentrations of T. gondii oocysts at the river outlet are likely to be very low. However, accumulation of oocysts in the estuarine areas may be large enough to contaminate estuarine/marine filter-feeding molluscs and snails on which seals and other marine mammals may feed. Potential maximum concentrations of T. gondii oocysts in runoff are reached at the beginning of the snowmelt period with maxima varying with discharge rates into rivers and how far upstream oocysts are discharged. Meteorological conditions during the snowmelt period can affect simulated concentrations of oocysts. These findings support the hypothesis that T. gondii oocysts carried in snowmelt runoff could be a source of T. gondii infection for marine mammals in the Canadian Arctic, and for Arctic human populations that hunt and consume raw meat from marine mammals.

  9. Impacts of Human Activity on the Microbial Communities of Devon Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Bywaters, K. B.; Burton, A. S.; Wallace, S. L.; Glass, B. J.

    2016-09-01

    The impacts of human activities on microbial communities in arctic environments are poorly understood. This project compares the distribution of microbes at the HMP Mars analog site prior to and after human settlement.

  10. Regional Climate Modeling over the Glaciated Regions of the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Gready, Benjamin P.

    The Canadian Arctic Islands (CAI) contain the largest concentration of terrestrial ice outside of the continental ice sheets. Mass loss from this region has recently increased sharply due to above average summer temperatures. Thus, increasing the understanding of the mechanisms responsible for mass loss from this region is critical. Previously, Regional Climate Models (RCMs) have been utilized to estimate climatic balance over Greenland and Antarctica. This method offers the opportunity to study a full suite of climatic variables over extensive spatially distributed grids. However, there are doubts of the applicability of such models to the CAI, given the relatively complex topography of the CAI. To test RCMs in the CAI, the polar version of the regional climate model MM5 was run at high resolution over Devon Ice Cap. At low altitudes, residuals (computed through comparisons with in situ measurements) in the net radiation budget were driven primarily by residuals in net shortwave (NSW) radiation. Residuals in NSW are largely due to inaccuracies in modeled cloud cover and modeled albedo. Albedo on glaciers and ice sheets is oversimplified in Polar MM5 and its successor, the Polar version of the Weather Research and Forecast model (Polar WRF), and is an obvious place for model improvement. Subsequently, an inline parameterization of albedo for Polar WRF was developed as a function of the depth, temperature and age of snow. The parameterization was able to reproduce elevation gradients of seasonal mean albedo derived from satellite albedo measurements (MODIS MOD10A1 daily albedo), on the western slope of the Greenland Ice Sheet for three years. Feedbacks between modelled albedo and modelled surface energy budget components were identified. The shortwave radiation flux feeds back positively with changes to albedo, whereas the longwave, turbulent and ground energy fluxes all feed back negatively, with a maximum combined magnitude of two thirds of the shortwave feedback

  11. Large-scale temperature and salinity changes in the upper Canadian basin of the Arctic Ocean at a time of a drastic Arctic Oscillation inversion

    NASA Astrophysics Data System (ADS)

    Bourgain, P.; Gascard, J. C.; Shi, J.; Zhao, J.

    2012-05-01

    Between 2008 and 2010, the Arctic Oscillation index over Arctic regions shifted from positive values corresponding to more cyclonic conditions prevailing during IPY period (2007-2008) to extremely negative values corresponding to strong anticyclonic conditions in 2010. In this context, we investigated the recent large scale evolution of the upper Western Arctic Ocean based on temperature and salinity summertime observations collected during icebreaker campaigns and from Ice-Tethered Platforms (ITP) drifting across the region in 2008 and 2010. Particularly, we focused on (1) the freshwater content which was extensively studied during previous years, (2) the Near Surface Temperature Maximum due to incoming solar radiation and (3) the water masses advected from the Pacific and Atlantic Oceans into the deep Arctic Ocean. The observations revealed a freshwater content change in the Canadian basin during this time period. South of 80° N, the freshwater content increased, while north of 80° N, less freshening occurred in 2010 compared to 2008. This was more likely due to the strong anticyclonicity characteristic of a low AO index mode that enhanced both a wind-generated Ekman pumping in the Beaufort Gyre and a diversion of the Siberian rivers runoff toward the Eurasian basin at the same time. The Near Surface Temperature Maximum due to incoming solar radiation was almost 1 °C colder in the Southern Canada basin (south of 75° N) in 2010 compared to 2008 which contrasted with the positive trend observed during previous years. This was more likely due to higher summer sea ice concentration in 2010 compared to 2008 in that region, and surface albedo feedback reflecting more sun radiation back in space. The Pacific waters were also subjected to strong spatial and temporal variability between 2008 and 2010. In the Canada basin, both Summer and Winter Pacific waters influence increased between 75° N and 80° N. This was more likely due to a strong recirculation within the

  12. Active seafloor gas vents on the Shelf and upper Slope in Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Hughes Clarke, J. E.; Blasco, S.; Taylor, A. E.; Melling, H.; Vagle, S.; Conway, K.; Riedel, M.; Lundsten, E.; Gwiazda, R.

    2012-12-01

    In the Canadian Arctic shelf and upper slope, a thermal disturbance caused by sea level rise at the end of the last glacial period, is still propagating into the subsurface and heating shelf sediments, where submerged terrestrial permafrost and gas hydrate, and marine gas hydrate are believed to occur in close proximity. On-going studies show evidence of gas venting in association with three distinct environments: Pingo-Like-Features (PLF) on the mid-shelf; along the shelf edge near the 100m contour; and ~1 km wide circular topographic features on the upper continental slope. Observations with a Remotely Operated Vehicle (ROV) show that methane is venting vigorously over point sources on the PLF's on the mid-shelf, and diffusely along the shelf edge. The stable isotopic composition of methane emanating from these environments indicates a microbial origin for the venting gas. Their negligible radiocarbon content indicates a geological source, as opposed to methangenisis associated with modern sediments. This is consistent with the change in the thermal regime produced by the last transgression. During glacial periods lower sea level exposed the current shelf to frigid sub-aerial temperatures. As a result, some areas of the shelf are underlain by >600m of ice-bonded permafrost with the base of methane hydrate stability at >1000m depths. The marine transgression imposed a change in mean annual surface temperature from -15°C or lower, to mean annual sea bottom temperatures near 0°C. The thermal disturbance is still propagating into the subsurface, stimulating the decomposition of both terrestrial permafrost and gas hydrate at depth and liberating methane. The PLF vents are believed to be sourced from the top of the gas hydrate stability field, while the gas emanating along the shelf edge can be from the decomposition of gas trapped in the permafrost or gas-hydrate underneath the continental shelf. The occurrence of water column flares over the distinctive circular

  13. Spatial, temporal, and source variations of hydrocarbons in marine sediments from Baffin Bay, Eastern Canadian Arctic.

    PubMed

    Foster, Karen L; Stern, Gary A; Carrie, Jesse; Bailey, Joscelyn N-L; Outridge, Peter M; Sanei, Hamed; Macdonald, Robie W

    2015-02-15

    With declining sea ice conditions in Arctic regions owing to changing climate, the large prospective reservoirs of oil and gas in Baffin Bay and Davis Strait are increasingly accessible, and the interest in offshore exploration and shipping through these regions has increased. Both of these activities are associated with the risk of hydrocarbon releases into the marine ecosystem. However, hydrocarbons are also present naturally in marine environments, in some cases deriving from oil seeps. We have analyzed hydrocarbon concentrations in eleven sediment cores collected from northern Baffin Bay during 2008 and 2009 Amundsen expeditions and have examined the hydrocarbon compositions in both pre- and post-industrial periods (i.e., before and after 1900) to assess the sources of hydrocarbons, and their temporal and spatial variabilities. Concentrations of ΣPAHs ranged from 341 to 2693 ng g(-1) dw, with concentrations in cores from sites within the North Water (NOW) Polynya generally higher. Individual PAH concentrations did not exceed concentrations of concern for marine aquatic life, with one exception found in a core collected within the NOW (one of the seven sediment core samples). Hydrocarbon biomarkers, including alkane profiles, OEP (odd-to-even preference), and TAR (terrigenous/aquatic ratios) values indicated that organic carbon at all sites is derived from both terrigenous higher plants and marine algae, the former being of greater significance at coastal sites, and the latter at the deepest sites at the southern boundary of the NOW. Biomarker ratios and chemical profiles indicate that petrogenic sources dominate over combustion sources, and thus long-range atmospheric transport is less significant than inputs from weathering. Present-day and historic pre-1900 hydrocarbon concentrations exhibited less than an order of magnitude difference for most compounds at all sites. The dataset presented here provides a baseline record of hydrocarbon concentrations in

  14. Spatial, temporal, and source variations of hydrocarbons in marine sediments from Baffin Bay, Eastern Canadian Arctic.

    PubMed

    Foster, Karen L; Stern, Gary A; Carrie, Jesse; Bailey, Joscelyn N-L; Outridge, Peter M; Sanei, Hamed; Macdonald, Robie W

    2015-02-15

    With declining sea ice conditions in Arctic regions owing to changing climate, the large prospective reservoirs of oil and gas in Baffin Bay and Davis Strait are increasingly accessible, and the interest in offshore exploration and shipping through these regions has increased. Both of these activities are associated with the risk of hydrocarbon releases into the marine ecosystem. However, hydrocarbons are also present naturally in marine environments, in some cases deriving from oil seeps. We have analyzed hydrocarbon concentrations in eleven sediment cores collected from northern Baffin Bay during 2008 and 2009 Amundsen expeditions and have examined the hydrocarbon compositions in both pre- and post-industrial periods (i.e., before and after 1900) to assess the sources of hydrocarbons, and their temporal and spatial variabilities. Concentrations of ΣPAHs ranged from 341 to 2693 ng g(-1) dw, with concentrations in cores from sites within the North Water (NOW) Polynya generally higher. Individual PAH concentrations did not exceed concentrations of concern for marine aquatic life, with one exception found in a core collected within the NOW (one of the seven sediment core samples). Hydrocarbon biomarkers, including alkane profiles, OEP (odd-to-even preference), and TAR (terrigenous/aquatic ratios) values indicated that organic carbon at all sites is derived from both terrigenous higher plants and marine algae, the former being of greater significance at coastal sites, and the latter at the deepest sites at the southern boundary of the NOW. Biomarker ratios and chemical profiles indicate that petrogenic sources dominate over combustion sources, and thus long-range atmospheric transport is less significant than inputs from weathering. Present-day and historic pre-1900 hydrocarbon concentrations exhibited less than an order of magnitude difference for most compounds at all sites. The dataset presented here provides a baseline record of hydrocarbon concentrations in

  15. Comparison of Physical Properties of Marine and Arctic Gas-Hydrate-Bearing Deposits

    NASA Astrophysics Data System (ADS)

    Winters, W. J.; Walker, M.; Collett, T. S.; Bryant, S. L.; Novosel, I.; Wilcox-Cline, R.; Bing, J.; Gomes, M. L.

    2009-12-01

    Gas hydrate (GH) occurs in both marine settings and in arctic environments within a wide variety of sediment types. Grain-size analyses from both environments indicate that intrinsic host-sediment properties have a strong influence on gas-hydrate distribution and morphologic characteristics. Depending on the amount formed or dissociated, gas hydrate can significantly change in situ sediment acoustic, mechanical, and hydraulic properties. The U.S. Geological Survey, in cooperation with the U.S. Dept. of Energy, BP Expl.-Alaska, Nat. GH Prog. of India, Canadian Geological Survey, Int. Ocean Drilling Program, Japan Oil Gas and Metals Nat. Corp., Japan Pet. Expl. Co., Int. Marine Past Global Changes Study (IMAGES) program, and Paleoceanography of the Atlantic and Geochemistry (PAGE) program, determined physical properties from marine and arctic sediments and their relation to the presence of GH. At two arctic sites, the Mount Elbert well on the Alaskan North Slope and the Mallik wells on the Mackenzie Delta, NWT, >10-m thick gas-hydrate-bearing (GHB) sandy deposits are capped by finer-grained sediments that may reduce gas migration. In the Mount Elbert well, average median grain sizes (MGS) for the two thickest GHB deposits are 65 and 60 µm. Finer-grained (average MGS of 9 and 28 µm) sediments have plug permeabilities that are 300 and 14 times smaller than underlying GHB sediment. Average MGS of GHB sediment from the Mallik 2L well is ~ 111 µm, compared to overlying sediment with an average MGS of ~ 32 µm. Gas hydrate morphology in the Gulf of Mexico (GOM) and offshore India is substantially more complex than in the arctic, and is related to pervasive, although not exclusive, finer-grained deposits. Massive, several-cm thick, GH layers were recovered in piston cores in the northern GOM, in sediment with little visible lithologic variability (average MGS ~ 0.8 µm). In wells off the east coast of India, GH was present in sand-rich, fractured clay, and reservoirs

  16. Ice-atmosphere interactions in the Canadian High Arctic: Implications for the thermo-mechanical evolution of terrestrial ice masses

    NASA Astrophysics Data System (ADS)

    Wohlleben, Trudy M. H.

    Canadian High Arctic terrestrial ice masses and the polar atmosphere evolve codependently, and interactions between the two systems can lead to feedbacks, positive and negative. The two primary positive cryosphere-atmosphere feedbacks are: (1) The snow/ice-albedo feedback (where area changes in snow and/or ice cause changes in surface albedo and surface air temperatures, leading to further area changes in snow/ice); and (2) The elevation - mass balance feedback (where thickness changes in terrestrial ice masses cause changes to atmospheric circulation and precipitation patterns, leading to further ice thickness changes). In this thesis, numerical experiments are performed to: (1) quantify the magnitudes of the two feedbacks for chosen Canadian High Arctic terrestrial ice masses; and (2) to examine the direct and indirect consequences of surface air temperature changes upon englacial temperatures with implications for ice flow, mass flux divergence, and topographic evolution. Model results show that: (a) for John Evans Glacier, Ellesmere Island, the magnitude of the terrestrial snow/ice-albedo feedback can locally exceed that of sea ice on less than decadal timescales, with implications for glacier response times to climate perturbations; (b) although historical air temperature changes might be the direct cause of measured englacial temperature anomalies in various glacier and ice cap accumulation zones, they can also be the indirect cause of their enhanced diffusive loss; (c) while the direct result of past air temperature changes has been to cool the interior of John Evans Glacier, and its bed, the indirect result has been to create and maintain warm (pressure melting point) basal temperatures in the ablation zone; and (d) for Devon Ice Cap, observed mass gains in the northwest sector of the ice cap would be smaller without orographic precipitation and the mass balance---elevation feedback, supporting the hypothesis that this feedback is playing a role in the

  17. Optical Characterisation of Suspended Particles in the Mackenzie River Plume (Canadian Arctic Ocean) and Implications for Ocean Colour Remote Sensing

    NASA Technical Reports Server (NTRS)

    Doxaran, D.; Ehn, J.; Belanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-01-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future

  18. Optical characterisation of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean) and implications for ocean colour remote sensing

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Ehn, J.; Bélanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-08-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future

  19. "Canadian" Radiogenic Isotope Signature of Younger Dryas Age Sediments from the Central Arctic and Fram Strait Areas

    NASA Astrophysics Data System (ADS)

    Maccali, J.; Hillaire-Marcel, C.; Not, C.; Poirier, A.

    2011-12-01

    Recent work on sediment-core from the central Lomonosov Ridge (TWC- & MC-18) yielded evidence for active Ice-Rafted Deposition (IRD) during the Younger Dryas (YD), following a sedimentary hiatus spanning broadly the Last Glacial Maximum (LGM) [Hanslik et al., Quaternary Sci. Rev. 29: 3430-3441, 2010]. The YD interval is also recorded in a core raised from below outflowing Arctic sea-ice and water masses in the Fram Strait area (MC-16), thus raising the issue of the role of freshwater/sea-ice export from the Arctic in the YD-slowdown of the Atlantic Meridional Overturning Circulation (AMOC). We report here about mineralogical, geochemical and radiogenic isotope studies (Pb, Nd, Sr) of these YD-sediments in relation with potential sea-ice/sediment source areas in the Arctic Ocean. Three major isotopic sectors have variably contributed to IRD along the Trans-Polar Drift route towards Fram Strait since the LGM : i) Arctic Canada (206Pb/204Pb ≥ 18.854, epsilon-Nd ≤ -13.2, 87Sr/86Sr ≥ 0.721), ii) Northern Russia- (206Pb/204Pb ≤ 18.45, epsilon-Nd ≤ -10.3 and 87Sr/86Sr ≤ 0.715) and iii) Greenland- (YD; 206Pb/204Pb ≤ 18.65, epsilon-Nd ≤ -12.5 and 87Sr/86Sr ≤ 0.718). Whereas distinct mixing-trends are observed prior and after the YD in the Fram Strait area, the YD itself depicts at both sites a strong isotopic excursion towards the Canadian source with isotopic ratios of 18.84, -13.2 and 0.721 respectively for 206Pb/204Pb, epsilon-Nd and 87Sr/86Sr. Both sites also recorded a 5-fold higher IRD rates during the YD, in comparison with their respective mean Holocene rate. In MC-18, a 5-fold higher 230Th-excess also characterizes the YD unit which shows high carbonate contents, in its silt to sand fractions, with equal amounts of calcite and dolomite, also pointing to a major role of Canadian supplies. These features are interpreted as an indication for a strong freshwater pulse from northwestern Canada, enhancing sea-ice production in the Beaufort Sea, thus a

  20. Contagious Ecthyma, Rangiferine Brucellosis, and Lungworm Infection in a Muskox ( Ovibos moschatus ) from the Canadian Arctic, 2014.

    PubMed

    Tomaselli, Matilde; Dalton, Chimoné; Duignan, Pádraig J; Kutz, Susan; van der Meer, Frank; Kafle, Pratap; Surujballi, Om; Turcotte, Claude; Checkley, Sylvia

    2016-07-01

    An adult male muskox ( Ovibos moschatus ), harvested on 26 August 2014 on Victoria Island, Nunavut, in the Canadian Arctic, had proliferative dermatitis on the muzzle and fetlocks suggestive of contagious ecthyma or orf (Parapoxvirus). Histopathologic features of the lesions were consistent with this diagnosis. Orf virus DNA, phylogenetically similar to an isolate from a captive muskox of the Minnesota Zoo, US, was detected in the lesions by PCR using Parapoxvirus primers. Additionally, there was a metaphyseal abscess with a cortical fistula in the right metacarpus from which Brucella suis biovar 4 was isolated and identification supported by PCR. Brucella spp. antibodies were detected in serum. Finally, 212 nodules were dissected from the lungs. Fecal analysis and lung examination demonstrated co-infection with the lungworms Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis. The zoonotic potential of orf and rangiferine brucellosis adds an important public health dimension to this case, particularly given that muskoxen are a valuable source of food for Arctic residents. Careful examination of these pathogens at a population level is needed as they may contribute to muskox population decline and potentially constitute a driver of food insecurity for local communities. This case underscores the importance of wildlife health surveillance as a management tool to conserve wildlife populations and maintain food security in subsistence-oriented communities.

  1. Methylmercury and selenium speciation in different tissues of beluga whales (Delphinapterus leucas) from the western Canadian Arctic.

    PubMed

    Lemes, Marcos; Wang, Feiyue; Stern, Gary A; Ostertag, Sonja K; Chan, Hing Man

    2011-12-01

    Monitoring data have shown that the total monomethylmercury (CH(3) Hg(+) and its complexes; collectively referred as MeHg hereafter) concentrations in Arctic marine mammals have remained very high in recent decades. Toward a better understanding of the metabolic and toxicological implications of these high levels of MeHg, we report here on the molecular forms of MeHg in the muscle, brain, liver, and kidneys of 10 beluga whales from the western Canadian Arctic. In all tissues analyzed, monomethylmercury was found to be dominated by methylmercuric cysteinate, a specific form of MeHg believed to be able to transport across the blood-brain barrier. Another MeHg-thiol complex, methylmercuric glutathionate, was also detected in the muscle and, to a much lesser extent, in the liver and brain tissues. Furthermore, a profound inorganic Hg peak was detected in the liver and brain tissues, which showed the same retention time as a selenium (Se) peak, suggesting the presence of an Hg-Se complex, most likely an inorganic Hg complex with a selenoamino acid. These results provide the first analytical support that the binding of MeHg with glutathione and Se may have protected beluga whales from the toxic effect of high concentrations of MeHg in their body.

  2. Model simulated volume fluxes through the Canadian Arctic Archipelago and Davis Strait: Linking monthly variations to forcing in different seasons

    NASA Astrophysics Data System (ADS)

    Lu, Youyu; Higginson, Simon; Nudds, Shannon; Prinsenberg, Simon; Garric, Gilles

    2014-03-01

    The solution of a 10 year simulation of the Arctic Ocean, produced using a 6 km resolution coupled ocean and sea-ice model, is analyzed to understand the variability, control, and forcing mechanisms of the volume fluxes through the Canadian Arctic Archipelago (CAA) and Davis Strait (DS). The analysis focuses on variability at monthly time scales. Analysis confirms the "control" of volume fluxes through the CAA, proposed in previous studies, by (1) variations of sea surface height (SSH) in the "upstream" regions and the relationship of this control to alongshore wind in the Beaufort Sea and (2) by SSH in the "downstream" region in Baffin Bay that may be related to wind stress in Baffin Bay and the northern Labrador Sea. The effectiveness of these control and forcing mechanisms vary for fluxes through different sections and for different seasons. Variation of the southward flux through DS is directly influenced by fluxes through Nares Strait (NS) and Barrow Strait (BS) in summer, fall, and winter. In spring, variations of the southward and northward fluxes through DS are closely related to each other and correspond to changes in the SSH along pathways of the Irminger Current, and the East and West Greenland Currents.

  3. Contaminants in a soil-plant-lemming food chain system at a military radar site in the Canadian Arctic

    SciTech Connect

    Dushenko, W.T.; Bright, D.A.; Grundy, S.L.; Reimer, K.J.

    1995-12-31

    Environmental assessment and impact studies have been conducted at Distant Early Warning (DEW) Line and other radar sites across the Canadian Arctic and Labrador, as well as Arctic background locations since 1989. Some of the major contaminants found in soils and plants in the vicinity of the stations include PCBs and inorganic elements such as lead, copper and zinc. The impact of these contaminants at higher levels of the food chain were examined using a soil-plant-lemming system in a sewage outfall (containing high soil concentrations of contaminants) and background areas at a radar site located at Cambridge Bay, NWT. Concentrations of PCBs in tissue samples from the sewage outfall were all significantly larger than background values with averages, in some cases, differing by an order of magnitude or more. Although the average PCB concentration declines from soils (average 1,600 ppb) to plants (average 9.3 ppb) in the outfall, plant-herbivore food chain biomagnification is indicated by a 6.5 fold increase in PCB concentration between whole lemming tissues (average 61 ppb) and plants. Levels in liver tissue were double this value (123 ppb) being comparable to values reported for predators of this species. The implications of these levels are discussed in terms of ecosystem toxicity using congener specific analysis.

  4. Methylmercury and selenium speciation in different tissues of beluga whales (Delphinapterus leucas) from the western Canadian Arctic.

    PubMed

    Lemes, Marcos; Wang, Feiyue; Stern, Gary A; Ostertag, Sonja K; Chan, Hing Man

    2011-12-01

    Monitoring data have shown that the total monomethylmercury (CH(3) Hg(+) and its complexes; collectively referred as MeHg hereafter) concentrations in Arctic marine mammals have remained very high in recent decades. Toward a better understanding of the metabolic and toxicological implications of these high levels of MeHg, we report here on the molecular forms of MeHg in the muscle, brain, liver, and kidneys of 10 beluga whales from the western Canadian Arctic. In all tissues analyzed, monomethylmercury was found to be dominated by methylmercuric cysteinate, a specific form of MeHg believed to be able to transport across the blood-brain barrier. Another MeHg-thiol complex, methylmercuric glutathionate, was also detected in the muscle and, to a much lesser extent, in the liver and brain tissues. Furthermore, a profound inorganic Hg peak was detected in the liver and brain tissues, which showed the same retention time as a selenium (Se) peak, suggesting the presence of an Hg-Se complex, most likely an inorganic Hg complex with a selenoamino acid. These results provide the first analytical support that the binding of MeHg with glutathione and Se may have protected beluga whales from the toxic effect of high concentrations of MeHg in their body. PMID:21953916

  5. Contagious Ecthyma, Rangiferine Brucellosis, and Lungworm Infection in a Muskox ( Ovibos moschatus ) from the Canadian Arctic, 2014.

    PubMed

    Tomaselli, Matilde; Dalton, Chimoné; Duignan, Pádraig J; Kutz, Susan; van der Meer, Frank; Kafle, Pratap; Surujballi, Om; Turcotte, Claude; Checkley, Sylvia

    2016-07-01

    An adult male muskox ( Ovibos moschatus ), harvested on 26 August 2014 on Victoria Island, Nunavut, in the Canadian Arctic, had proliferative dermatitis on the muzzle and fetlocks suggestive of contagious ecthyma or orf (Parapoxvirus). Histopathologic features of the lesions were consistent with this diagnosis. Orf virus DNA, phylogenetically similar to an isolate from a captive muskox of the Minnesota Zoo, US, was detected in the lesions by PCR using Parapoxvirus primers. Additionally, there was a metaphyseal abscess with a cortical fistula in the right metacarpus from which Brucella suis biovar 4 was isolated and identification supported by PCR. Brucella spp. antibodies were detected in serum. Finally, 212 nodules were dissected from the lungs. Fecal analysis and lung examination demonstrated co-infection with the lungworms Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis. The zoonotic potential of orf and rangiferine brucellosis adds an important public health dimension to this case, particularly given that muskoxen are a valuable source of food for Arctic residents. Careful examination of these pathogens at a population level is needed as they may contribute to muskox population decline and potentially constitute a driver of food insecurity for local communities. This case underscores the importance of wildlife health surveillance as a management tool to conserve wildlife populations and maintain food security in subsistence-oriented communities. PMID:27285415

  6. Distribution and diet of larval and juvenile Arctic cod ( Boreogadus saida) in the shallow Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Walkusz, Wojciech; Paulic, Joclyn E.; Williams, William J.; Kwasniewski, Slawomir; Papst, Michael H.

    2011-02-01

    The distribution and diet of larval and juvenile Arctic cod ( Boreogadus saida) were studied during summer 2005 in the coastal Canadian Beaufort Sea. A total of 275 individuals were captured and the highest abundance was observed at station depths of 20-30 m. This corresponds well with the location of the frontal zone where the Mackenzie River plume water and open sea water meet. Diet examinations were performed on 220 Arctic cod, which were found undamaged from sampling. We observed a gradual decrease in prey number per fish and increase in prey size as larvae grew which corresponded to a shift from Rotifera and nauplii towards larger copepodid stages. However, at all sizes, the larvae remain generalists and feed on a broad range of organisms. Environmental changes due to climate warming could have a two-fold impact on fish larvae feeding in the studied region. First, the potential for increased primary production may lead to increased zooplankton production that may impact the feeding and nutrition positively. On the other hand, greater discharge of turbid water from the Mackenzie River may reduce light penetration in the water column that may negatively influence the ability of visual predators to successively forage.

  7. Mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the Canadian Arctic

    PubMed Central

    Piwosz, Kasia; Wiktor, Józef Maria; Niemi, Andrea; Tatarek, Agnieszka; Michel, Christine

    2013-01-01

    Sea ice, a characteristic feature of polar waters, is home to diverse microbial communities. Sea-ice picoeukaryotes (unicellular eukaryotes with cell size <3 μm) have received little attention compared with diatoms that dominate the spring bloom in Arctic first-year sea ice. Here, we investigated the abundance of all picoeukaryotes, and of 11 groups (chlorophytes, cryptophytes, bolidophytes, haptophytes, Pavlovaphyceae, Phaeocystis spp., pedinellales, stramenopiles groups MAST-1, MAST-2 and MAST-6 and Syndiniales Group II) at 13 first-year sea-ice stations localized in Barrow Strait and in the vicinity of Cornwallis Island, Canadian Arctic Archipelago. We applied Catalyzed Reporter Deposition–Fluorescence In Situ Hybridization to identify selected groups at a single cell level. Pavlovaphyceae and stramenopiles from groups MAST-2 and MAST-6 were for the first time reported from sea ice. Total numbers of picoeukaryotes were significantly higher in the vicinity of Cornwallis Island than in Barrow Strait. Similar trend was observed for all the groups except for haptophytes. Chlorophytes and cryptophytes were the dominant plastidic, and MAST-2 most numerous aplastidic of all the groups investigated. Numbers of total picoeukaryotes, chlorophytes and MAST-2 stramenopiles were positively correlated with the thickness of snow cover. All studied algal and MAST groups fed on bacteria. Presence of picoeukaryotes from various trophic groups (mixotrophs, phagotrophic and parasitic heterotrophs) indicates the diverse ecological roles picoeukaryotes have in sea ice. Yet, >50% of total sea-ice picoeukaryote cells remained unidentified, highlighting the need for further study of functional and phylogenetic sea-ice diversity, to elucidate the risks posed by ongoing Arctic changes. PMID:23514779

  8. Predation pressure by avian predators suggests summer limitation of small-mammal populations in the Canadian Arctic.

    PubMed

    Therrien, J F; Gauthier, G; Korpimäki, E; Bêty, J

    2014-01-01

    Predation has been suggested to be especially important in simple food webs and less productive ecosystems such as the arctic tundra, but very few data are available to evaluate this hypothesis. We examined the hypothesis that avian predators could drive the population dynamics of two cyclic lemming species in the Canadian Arctic. A dense and diverse suite of predatory birds, including the Snowy Owl (Bubo scandiacus), the Rough-legged Hawk (Buteo lagopus), and the Long-tailed Jaeger (Stercorarius longicaudus), inhabits the arctic tundra and prey on collared (Dicrostonyx groenlandicus) and brown (Lemmus trimucronatus) lemmings during the snow-free period. We evaluated the predation pressure exerted by these predators by combining their numerical (variation in breeding and fledgling numbers) and functional (variation in diet and daily consumption rates) responses to variations in lemming densities over the 2004-2010 period. Breeding density and number of fledglings produced by the three main avian predators increased sharply without delay in response to increasing lemming densities. The proportion of collared lemmings in the diet of those predators was high at low lemming density (both species) but decreased as lemming density increased. However, we found little evidence that their daily consumption rates vary in relation to changes in lemming density. Total consumption rate by avian predators initially increased more rapidly for collared lemming but eventually leveled off at a much higher value for brown lemmings, the most abundant species at our site. The combined daily predation rate of avian predators exceeded the maximum daily potential growth rates of both lemming species except at the highest recorded densities for brown lemmings. We thus show, for the first time, that predation pressure exerted without delay by avian predators can limit populations of coexisting lemming species during the snow-free period, and thus, that predation could play a role in the

  9. Mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the Canadian Arctic.

    PubMed

    Piwosz, Kasia; Wiktor, Józef Maria; Niemi, Andrea; Tatarek, Agnieszka; Michel, Christine

    2013-08-01

    Sea ice, a characteristic feature of polar waters, is home to diverse microbial communities. Sea-ice picoeukaryotes (unicellular eukaryotes with cell size <3 μm) have received little attention compared with diatoms that dominate the spring bloom in Arctic first-year sea ice. Here, we investigated the abundance of all picoeukaryotes, and of 11 groups (chlorophytes, cryptophytes, bolidophytes, haptophytes, Pavlovaphyceae, Phaeocystis spp., pedinellales, stramenopiles groups MAST-1, MAST-2 and MAST-6 and Syndiniales Group II) at 13 first-year sea-ice stations localized in Barrow Strait and in the vicinity of Cornwallis Island, Canadian Arctic Archipelago. We applied Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization to identify selected groups at a single cell level. Pavlovaphyceae and stramenopiles from groups MAST-2 and MAST-6 were for the first time reported from sea ice. Total numbers of picoeukaryotes were significantly higher in the vicinity of Cornwallis Island than in Barrow Strait. Similar trend was observed for all the groups except for haptophytes. Chlorophytes and cryptophytes were the dominant plastidic, and MAST-2 most numerous aplastidic of all the groups investigated. Numbers of total picoeukaryotes, chlorophytes and MAST-2 stramenopiles were positively correlated with the thickness of snow cover. All studied algal and MAST groups fed on bacteria. Presence of picoeukaryotes from various trophic groups (mixotrophs, phagotrophic and parasitic heterotrophs) indicates the diverse ecological roles picoeukaryotes have in sea ice. Yet, >50% of total sea-ice picoeukaryote cells remained unidentified, highlighting the need for further study of functional and phylogenetic sea-ice diversity, to elucidate the risks posed by ongoing Arctic changes.

  10. Predation pressure by avian predators suggests summer limitation of small-mammal populations in the Canadian Arctic.

    PubMed

    Therrien, J F; Gauthier, G; Korpimäki, E; Bêty, J

    2014-01-01

    Predation has been suggested to be especially important in simple food webs and less productive ecosystems such as the arctic tundra, but very few data are available to evaluate this hypothesis. We examined the hypothesis that avian predators could drive the population dynamics of two cyclic lemming species in the Canadian Arctic. A dense and diverse suite of predatory birds, including the Snowy Owl (Bubo scandiacus), the Rough-legged Hawk (Buteo lagopus), and the Long-tailed Jaeger (Stercorarius longicaudus), inhabits the arctic tundra and prey on collared (Dicrostonyx groenlandicus) and brown (Lemmus trimucronatus) lemmings during the snow-free period. We evaluated the predation pressure exerted by these predators by combining their numerical (variation in breeding and fledgling numbers) and functional (variation in diet and daily consumption rates) responses to variations in lemming densities over the 2004-2010 period. Breeding density and number of fledglings produced by the three main avian predators increased sharply without delay in response to increasing lemming densities. The proportion of collared lemmings in the diet of those predators was high at low lemming density (both species) but decreased as lemming density increased. However, we found little evidence that their daily consumption rates vary in relation to changes in lemming density. Total consumption rate by avian predators initially increased more rapidly for collared lemming but eventually leveled off at a much higher value for brown lemmings, the most abundant species at our site. The combined daily predation rate of avian predators exceeded the maximum daily potential growth rates of both lemming species except at the highest recorded densities for brown lemmings. We thus show, for the first time, that predation pressure exerted without delay by avian predators can limit populations of coexisting lemming species during the snow-free period, and thus, that predation could play a role in the

  11. Factors Driving Potential Ammonia Oxidation in Canadian Arctic Ecosystems: Does Spatial Scale Matter?

    PubMed Central

    Banerjee, Samiran

    2012-01-01

    Ammonia oxidation is a major process in nitrogen cycling, and it plays a key role in nitrogen limited soil ecosystems such as those in the arctic. Although mm-scale spatial dependency of ammonia oxidizers has been investigated, little is known about the field-scale spatial dependency of aerobic ammonia oxidation processes and ammonia-oxidizing archaeal and bacterial communities, particularly in arctic soils. The purpose of this study was to explore the drivers of ammonia oxidation at the field scale in cryosols (soils with permafrost within 1 m of the surface). We measured aerobic ammonia oxidation potential (both autotrophic and heterotrophic) and functional gene abundance (bacterial amoA and archaeal amoA) in 279 soil samples collected from three arctic ecosystems. The variability associated with quantifying genes was substantially less than the spatial variability observed in these soils, suggesting that molecular methods can be used reliably evaluate spatial dependency in arctic ecosystems. Ammonia-oxidizing archaeal and bacterial communities and aerobic ammonia oxidation were spatially autocorrelated. Gene abundances were spatially structured within 4 m, whereas biochemical processes were structured within 40 m. Ammonia oxidation was driven at small scales (<1m) by moisture and total organic carbon, whereas gene abundance and other edaphic factors drove ammonia oxidation at medium (1 to 10 m) and large (10 to 100 m) scales. In these arctic soils heterotrophs contributed between 29 and 47% of total ammonia oxidation potential. The spatial scale for aerobic ammonia oxidation genes differed from potential ammonia oxidation, suggesting that in arctic ecosystems edaphic, rather than genetic, factors are an important control on ammonia oxidation. PMID:22081570

  12. Greenhouse Gas Emissions from Arctic Freshwaters: Approaches for Scaling UP

    NASA Astrophysics Data System (ADS)

    MacIntyre, S.; Cortés, A.; Cooke, M.; Sadro, S.; Kushner, P. J.

    2015-12-01

    Turbulence moderates emissions of greenhouse gases on a number of scales, and it, in turn, is moderated by processes which govern the stability of boundary layers. On the smallest scale, it mediates the fluxes of gases across the air-water interface; at intermediate scales, that is, the size of within lake eddies, it brings gases to the air-water interface; on a larger scale, eddies in the unstable atmospheric boundary layers transport gases away from water bodies and maintain concentration gradients and further, help sustain fluxes by inducing within lake turbulence. The winds and cooling which induce within-lake turbulence and over-lake boundary layers are moderated by weather patterns dependent on even larger scale physical processes. Using time series measurements of lake temperatures, surface meteorology, and profiles of temperature-gradient microstructure in Alaskan arctic lakes ranging from 0.1 to 150 ha in surface area, we quantify the dependency of turbulence in the water column and at the air-water interface on surface meteorology and lake size. We show the lake size dependent variability in the stability of atmospheric boundary layers. We illustrate the resulting lake-size and weather dependent variability in gas transfer coefficients and within lake mixing. Using cluster analysis, we identify dominant weather patterns in the Alaskan Arctic Region and link them to within lake mixing dynamics. We then illustrate the dependency of greenhouse gas emissions on variability in local weather, lake size, and weather patterns.

  13. The nature and fate of natural resins in the geosphere VI. Analysis of fossil resins from Axel Heiberg Island Canadian Arctic

    SciTech Connect

    Anderson, K.B. |; LePage, B.A.

    1995-06-01

    Ambers are well known and abundant in terrestrial sediments all over the world; however, due largely to the absence of definite morphological characteristics, the precise botanical origin of most amber samples, are at best, often a matter of speculation. This has severely restricted the usefulness of amber in paleobotanical and paleoecological interpretations. The molecular composition and structural characteristics of fossil resins however, may preserve evidence of their botanical origin, which could be of great value in both geochemical, paleobotanical, and paleoenvironmental studies. The remains of a number of exceptionally well-preserved Taxodiaceae-dominated swamp-forest communities have been identified in the sediments of the middle Eocene (45 million years old) Buchanan Lake Formation of Axel Heiberg Island, Canadian Arctic Archipelago. The amber collected from these ancient in situ forests provides a unique opportunity to characterize these resins chemically and taxonomically. Resinite associated with Metasequoia, Pinus and Pseudolarix has been characterized using Pyrolysis-Gas Chromatography-Mass Spectrometry. This method provides a direct analysis of the molecular structure and composition of the resin. In several cases, both bled resin and cone-resin samples have been characterized. The results of these analyses are presented and discussed. The implications of these results for the botanical origins of other ambers represented in the fossil record (including succinite) will also be discussed.

  14. Evaluation and control mechanisms of volume and freshwater export through the Canadian Arctic Archipelago in a high-resolution pan-Arctic ice-ocean model

    NASA Astrophysics Data System (ADS)

    McGeehan, Timothy; Maslowski, Wieslaw

    2012-03-01

    This study examined the 1979-2004 volume and freshwater fluxes through the Canadian Arctic Archipelago (CAA) and into the Labrador Sea using a high resolution (˜9 km) coupled ice-ocean model of the pan-Arctic region to provide a reference, compare with limited observational estimates, and investigate control mechanisms of this exchange. The 26-year mean volume and freshwater fluxes through Nares Strait were 0.77 Sv ± 0.17 Sv and 10.38 mSv ± 1.67 mSv respectively, while those through Lancaster Sound amounted to 0.76 Sv ± 0.12 Sv and 48.45 mSv ± 7.83 mSv respectively. The 26-year mean volume and freshwater fluxes through Davis Strait were 1.55 Sv ± 0.29 Sv and 62.66 mSv ± 11.67 mSv while the modeled Fram Strait branch provided very little (˜2%) freshwater into the Labrador Sea compared to the total CAA input. Compared to available observations, the model provides reasonable volume and freshwater fluxes, as well as sea ice thickness and concentration in the CAA. In Nares Strait and Lancaster Sound, volume flux anomalies were controlled by the sea surface height (SSH) gradient anomalies along the straits and freshwater anomalies were highly correlated with the volume anomalies. At least half of the variance in the time series of SSH gradient anomaly was due to SSH anomalies in northern Baffin Bay. The West Greenland Current (WGC) exhibits seasonality, with cross shelf flow (into the Labrador Sea) peaking in January/February/March, while reducing the northward flow across eastern Davis Strait. We hypothesize that the eddy-reduced northward flow of WGC results in the lower volume and SSH in Baffin Bay. This maximizes the SSH gradients between the Arctic Ocean and Baffin Bay, leading to maximum winter volume fluxes through Nares Strait and Lancaster Sound. Model limitations include the insufficient spatial resolution of atmospheric forcing (especially to account for the effects of local topography), the representation of river runoff into Hudson Bay and coastal

  15. Giardia assemblage A: human genotype in muskoxen in the Canadian Arctic

    PubMed Central

    Kutz, Susan J; Thompson, RC Andrew; Polley, Lydden; Kandola, Kami; Nagy, John; Wielinga, Caroline M; Elkin, Brett T

    2008-01-01

    As part of an ongoing program assessing the biodiversity and impacts of parasites in Arctic ungulates we examined 72 fecal samples from muskoxen on Banks Island, Northwest Territories, Canada for Giardia and Cryptosporidium. Cryptosporidium spp. were not detected, but 21% of the samples were positive for Giardia. Sequencing of four isolates of Giardia demonstrated G. duodenalis, Assemblage A, a zoonotic genotype. PMID:18808665

  16. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core.

    PubMed

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Dahl-Jensen, Dorthe

    2016-09-21

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called "bromine explosions" and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  17. Changes in cold tolerance due to a 14-day stay in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Livingstone, S. D.; Romet, T.; Keefe, A. A.; Nolan, R. W.

    1996-12-01

    Responses to cold exposure tests both locally and of the whole body were examined in subjects who stayed in the Arctic (average maximum and minimum temperatures -11 and -21° C respectively) for 14 days of skiing and sleeping in tents. These changes were compared to responses in subjects living working in Ottawa, Canada (average max. and min. temperatures -5 and -11° C respectively). The tests were done before the stay in the Arctic (Pre), immediately after the return (Post 1) and approximately 32 days after the return (Post 2). For the whole-body cold exposure each subject, wearing only shorts and lying on a rope mesh cot, was exposed to an ambient temperature of 10° C. There was no consistent response in the changes of metabolic or body temperature to this exposure in either of groups and, in addition, the changes over time were variable. Cold induced vasodilatation (CIVD) was determined by measuring temperature changes in the middle finger of the nondominant hand upon immersion in ice water for 30 min. CIVD was depressed after the Arctic exposure whilst during the Post 2 testing, although variable, did not return to the Pre values; the responses of the control group were similar. These results indicate that normal seasonal changes may be as important in adaptation as a stay in the Arctic. Caution is advised in the separation of seasonal effects when examining the changes in adaptation after exposure to a cold environment.

  18. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    PubMed Central

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-01-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement. PMID:27650478

  19. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    NASA Astrophysics Data System (ADS)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-09-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  20. Building Capacity: The University of the Arctic and Its Northern Canadian Context.

    ERIC Educational Resources Information Center

    Senkpiel, Aron

    2000-01-01

    A proposed university in the circumpolar North would have undergraduate and graduate programs, be interdisciplinary, collaborate with other Northern countries and universities, and offer a circumpolar course to develop understanding of the Arctic. After many false starts, most components are already in place; all that is needed is determination,…

  1. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core.

    PubMed

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Dahl-Jensen, Dorthe

    2016-01-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called "bromine explosions" and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement. PMID:27650478

  2. Multiple climatic signals inferred from the varved sediments of a coastal lake in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Amann, Benjamin; Lamoureux, Scott F.

    2016-04-01

    The Arctic is extremely sensitive to climate change, and an influential part of the global climate system. However, the assessment of climate change and impacts from the Arctic remains a challenge mainly due to short and sparse meteorological records. In this context, data from natural paleoclimate archives are fundamental to place climate variability into perspective and assess the sensitivity of Earth's climate to natural and anthropogenic forcings. In particular, Arctic lakes are excellent potential archives. They are sensitive to extreme seasonal variations in surface processes and have a limited direct human impact. Nevertheless, the study of Arctic lakes is an analytical and technical challenge because: (i) limnological information are often lacking due to difficult accessibility; (ii) 210Pb inventories are low and terrestrial macrofossils for 14C dating are rare, which limits the development of precise sediment chronologies; and (iii) sediment accumulation rates are often low, which may restrict the temporal resolution and length of the paleoclimate records. Here, we present a high-resolution record from the varved sediments (annual laminations) of a saline coastal lake located in the Canadian High Arctic (unofficial name Chevalier Lake; Melville Island, NT). The particular interest of this location is the catchment area: 152 times larger than the lake area (Ac = 350 km²; AL = 2.3 km²). This particularity generates high sedimentation rates, atypical of previously studied arctic lakes. Two sediment cores were recovered from the centre and a more proximal zone of the lake. We used microstratigraphy supported by X-ray fluorescence data (Zr/K for particle size, Fe/Rb for the winter clay cap distinction) to develop a precise and cross-dated varve chronology covering the last 400 years. Dating of the uppermost section could be validated with preliminary 137Cs data. Stratigraphical analysis reveals the presence of three sediment units within the meter

  3. Periglacial Landscape Stabilization Following Rapid Permafrost Degradation by Thermo-erosion, Bylot Island, Nunavut, Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Fortier, D.; Godin, E.; Perreault, N.; Levesque, E.

    2010-12-01

    and the subsequent colonization of stabilized slopes by vegetation changed the thermal properties of the soil which resulted in a thinning of the active layer and ground ice aggradation in the upper part of the permafrost. These negative feedback effects contributed to permafrost recovery and ground ice aggradation. The latent heat of this ice-rich zone will act as a buffer to global warming and contributes to the long-term stability of the gullies in the new periglacial landscape. Fortier, D., Allard, M. 2004. Late Holocene Syngenetic Ice-wedge Polygons Development, Bylot Island, Canadian Arctic Archipelago. Canadian Journal of Earth Sciences, 41: 997-1012. Fortier, D., Allard, M., Shur, Y. 2007. Observation of Rapid Drainage System Development by Thermal Erosion of Ice Wedges on Bylot Island, Canadian Arctic Archipelago. Permafrost and Periglacial Processes, 18: 229-243. Godin, E., Fortier, D. (in press) Geomorphology of thermo-erosion gullies - case study from Bylot Island, Nunavut, Canada. Proceedings 6th Canadian Permafrost Conference and 63rd Canadian Geotechnical Conference, Calgary, October 2010.

  4. Net Ecosystem Production of Polar Desert and Wetland Landscapes in the Rapidly Changing Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Emmerton, C. A.; St Louis, V. L.; Humphreys, E.; Barker, J. D.; Gamon, J. A.; Pastorello, G.

    2014-12-01

    A rapidly warming and wetting Arctic climate is changing the net ecosystem production (NEP) of northern landscapes and subsequent exchange of carbon dioxide (CO2) with the atmosphere. Assessments of northern terrestrial NEP have focused mostly on the rich peatland landscapes of the low Arctic, with far fewer studies from expansive, but sparse, high Arctic polar landscapes. Consequently, how these ecosystems may respond to a warming and wetting climate is still a key gap in our understanding of global carbon feedbacks. We used multi-season eddy covariance measurements to quantify growing season (June to September) NEP on contrasting polar desert and meadow wetland landscapes near Lake Hazen on northern Ellesmere Island (81ºN), in Canada's high Arctic. We also used variation in contemporary NEP and weather to improve our understanding of potential future carbon cycling in a warmer and wetter high Arctic climate. During a typical growing season, we found that a dry polar desert landscape accumulated only 6.6±1.2 g C m-2 similar to other high Arctic sites and consistent with cold, barren soils with weak plant growth. Desert NEP coincided strongest with landscape moisture, rather than heating, with increased NEP occurring during drier conditions when soil heterotrophic rates were lowest. With a nearly constant but varying supply of water, the productive meadow wetland accumulated 13 times more carbon (86.1±16.9 g C m-2) than the desert during the growing season. NEP at the wetland was similar to comparable landscapes much further south, owing to continuous 24-hour daylight and typically clear-skies surrounding Lake Hazen. Wetland soils showed a consistent strong burst of CO2 to the atmosphere each spring (min. NEP: -2.5 µmol CO2 s-1 m-2) and a well-defined peak in July productivity (3.9-4.4 µmol CO2 s-1 m-2). Wetland NEP associated positively and strongly with both landscape heating and moisture, suggesting that autotrophic limitations other than water or heat

  5. Some sources and sinks of monomethyl and inorganic mercury on Ellesmere Island in the Canadian High Arctic.

    PubMed

    St Louis, Vincent L; Sharp, Martin J; Steffen, Alexandra; May, Al; Barker, Joel; Kirk, Jane L; Kelly, David J A; Arnott, Shelley E; Keatley, Bronwyn; Smol, John P

    2005-04-15

    We identified some of the sources and sinks of monomethyl mercury (MMHg) and inorganic mercury (HgII) on Ellesmere Island in the Canadian High Arctic. Atmospheric Hg depletion events resulted in the deposition of Hg(II) into the upper layers of snowpacks, where concentrations of total Hg (all forms of Hg) reached over 20 ng/L. However, our data suggest that much of this deposited Hg(II) was rapidly photoreduced to Hg(0) which then evaded back to the atmosphere. As a result, we estimate that net wet and dry deposition of Hg(II) during winter was lower at our sites (0.4-5.9 mg/ha) than wet deposition in more southerly locations in Canada and the United States. We also found quite high concentrations of monomethyl Hg (MMHg) in snowpacks (up to 0.28 ng/L), and at times, most of the Hg in snowpacks was present as MMHg. On the Prince of Wales Icefield nearthe North Water Polynya, we observed a significant correlation between concentrations of Cl and MMHg in snow deposited in the spring, suggesting a marine source of MMHg. We hypothesize that dimethyl Hg fluxes from the ocean to the atmosphere through polynyas and open leads in ice, and is rapidly photolyzed to MMHgCl. We also found that concentrations of MMHg in initial snowmelt on John Evans Glacier (up to 0.24 ng/L) were higher than concentrations of MMHg in the snowpack (up to 0.11 ng/L), likely due to either sublimation of snow or preferential leaching of MMHg from snow during the initial melt phase. This springtime pulse of MMHg to the High Arctic, in conjunction with climate warming and the thinning and melting of sea ice, may be partially responsible for the increase in concentrations of Hg observed in certain Arctic marine mammals in recent decades. Concentrations of MMHg in warm and shallow freshwater ponds on Ellesmere Island were also quite high (up to 3.0 ng/L), leading us to conclude that there are very active regions of microbial Hg(II) methylation in freshwater systems during the short summer season in the

  6. Composition and meteorological changes associated with a strong stratospheric intrusion event in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoyi; Strong, Kimberly; Conway, Stephanie; Tarasick, David; Osman, Mohammed; Richter, Andreas; Blechschmidt, Anne; Manney, Gloria

    2015-04-01

    Stratosphere-troposphere exchange (STE) provides a mechanism for trace gas transport between the lower stratosphere and the troposphere. Intense downward stratospheric intrusions may significantly affect the oxidizing capacity of the troposphere. Most STE events occur in tropical and mid-latitude regions, with less known about STE in the polar regions. In this work, we present an observation and modelling study of a strong stratospheric intrusion in the high Arctic (Eureka, 80°N) in March 2013, which led to an increase of total ozone and BrO columns observed by both ground-based and satellite instruments. The meteorological conditions for this event were similar to those observed for STEs associated with cold fronts. Before the cold front arrived at Eureka, the surface temperature first increased from -25.3°C (25 March 13:00 UTC) to -14.5°C (27 March 20:00 UTC) and then dropped to -36.4°C (29 March 6:00 UTC) after the front passed by. Meanwhile, the ground-level pressure decreased from 103.8 kPa to 101.8 kPa, then rose back to 102.6 kPa. Ozonesonde data (27 March 23:15 UTC) showed unusually high ozone (>100 ppbv) above ~3 km altitude, while the relative humidity profile indicated that the airmass was of stratospheric origin (very low relative humidity). The thermal tropopause height was ~9 km, based on a uniform lapse rate of 3.9 K/km from surface to 9 km. From ECMWF Interim data, the airmass with high relative potential vorticity (4 pvu) extended down to 3 km. In addition, HYSPLIT model ensemble back-trajectories show a clear Rossby wave signature in the upper troposphere during this event, which could explain the intrusion. However, there are no strong downwelling layers along the trajectories, which indicates that the intrusion may have occurred close to Eureka. Trace gas composition data from three ground-based spectrometers and the GOME-2 satellite instrument are presented in this work. Ozone vertical column densities (VCDs) measured by two Zenith

  7. Vegetation, plant biomass, and net primary productivity patterns in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Gould, W. A.; Raynolds, M.; Walker, D. A.

    2003-01-01

    We have developed maps of dominant vegetation types, plant functional types, percent vegetation cover, aboveground plant biomass, and above and belowground annual net primary productivity for Canada north of the northern limit of trees. The area mapped covers 2.5 million km2 including glaciers. Ice-free land covers 2.3 million km2 and represents 42% of all ice-free land in the Circumpolar Arctic. The maps combine information on climate, soils, geology, hydrology, remotely sensed vegetation classifications, previous vegetation studies, and regional expertise to define polygons drawn using photo-interpretation of a 1:4,000,000 scale advanced very high resolution radiometer (AVHRR) color infrared image basemap. Polygons are linked to vegetation description, associated properties, and descriptive literature through a series of lookup tables in a graphic information systems (GIS) database developed as a component of the Circumpolar Arctic Vegetation Map (CAVM) project. Polygons are classified into 20 landcover types including 17 vegetation types. Half of the region is sparsely vegetated (<50% vegetation cover), primarily in the High Arctic (bioclimatic subzones A-C). Whereas most (86%) of the estimated aboveground plant biomass (1.5 × 1015 g) and 87% of the estimated above and belowground annual net primary productivity (2.28 × 1014 g yr-1) are concentrated in the Low Arctic (subzones D and E). The maps present more explicit spatial patterns of vegetation and ecosystem attributes than have been previously available, the GIS database is useful in summarizing ecosystem properties and can be easily updated and integrated into circumpolar mapping efforts, and the derived estimates fall within the range of current published estimates.

  8. Differences in mercury bioaccumulation between polar bears (Ursus maritimus) from the Canadian high- and sub-Arctic.

    PubMed

    St Louis, Vincent L; Derocher, Andrew E; Stirling, Ian; Graydon, Jennifer A; Lee, Caroline; Jocksch, Erin; Richardson, Evan; Ghorpade, Sarah; Kwan, Alvin K; Kirk, Jane L; Lehnherr, Igor; Swanson, Heidi K

    2011-07-15

    Polar bears (Ursus maritimus) are being impacted by climate change and increased exposure to pollutants throughout their northern circumpolar range. In this study, we quantified concentrations of total mercury (THg) in the hair of polar bears from Canadian high- (southern Beaufort Sea, SBS) and sub- (western Hudson Bay, WHB) Arctic populations. Concentrations of THg in polar bears from the SBS population (14.8 ± 6.6 μg g(-1)) were significantly higher than in polar bears from WHB (4.1 ± 1.0 μg g(-1)). On the basis of δ(15)N signatures in hair, in conjunction with published δ(15)N signatures in particulate organic matter and sediments, we estimated that the pelagic and benthic food webs in the SBS are ∼ 4.7 and ∼ 4.0 trophic levels long, whereas in WHB they are only ∼ 3.6 and ∼ 3.3 trophic levels long. Furthermore, the more depleted δ(13)C ratios in hair from SBS polar bears relative to those from WHB suggests that SBS polar bears feed on food webs that are relatively more pelagic (and longer), whereas polar bears from WHB feed on those that are relatively more benthic (and shorter). Food web length and structure accounted for ∼ 67% of the variation we found in THg concentrations among all polar bears across both populations. The regional difference in polar bear hair THg concentrations was also likely due to regional differences in water-column concentrations of methyl Hg (the toxic form of Hg that biomagnifies through food webs) available for bioaccumulation at the base of the food webs. For example, concentrations of methylated Hg at mid-depths in the marine water column of the northern Canadian Arctic Archipelago were 79.8 ± 37.3 pg L(-1), whereas, in HB, they averaged only 38.3 ± 16.6 pg L(-1). We conclude that a longer food web and higher pelagic concentrations of methylated Hg available to initiate bioaccumulation in the BS resulted in higher concentrations of THg in polar bears from the SBS region compared to those inhabiting the western

  9. Stable isotope probing analysis of the diversity and activity of methanotrophic bacteria in soils from the Canadian high Arctic.

    PubMed

    Martineau, Christine; Whyte, Lyle G; Greer, Charles W

    2010-09-01

    The melting of permafrost and its potential impact on CH(4) emissions are major concerns in the context of global warming. Methanotrophic bacteria have the capacity to mitigate CH(4) emissions from melting permafrost. Here, we used quantitative PCR (qPCR), stable isotope probing (SIP) of DNA, denaturing gradient gel electrophoresis (DGGE) fingerprinting, and sequencing of the 16S rRNA and pmoA genes to study the activity and diversity of methanotrophic bacteria in active-layer soils from Ellesmere Island in the Canadian high Arctic. Results showed that most of the soils had the capacity to oxidize CH(4) at 4 degrees C and at room temperature (RT), but the oxidation rates were greater at RT than at 4 degrees C and were significantly enhanced by nutrient amendment. The DGGE banding patterns associated with active methanotrophic bacterial populations were also different depending on the temperature of incubation and the addition of nutrients. Sequencing of the 16S rRNA and pmoA genes indicated a low diversity of the active methanotrophic bacteria, with all methanotroph 16S rRNA and pmoA gene sequences being related to type I methanotrophs from Methylobacter and Methylosarcina. The dominance of type I methanotrophs over type II methanotrophs in the native soil samples was confirmed by qPCR of the 16S rRNA gene with primers specific for these two groups of bacteria. The 16S rRNA and pmoA gene sequences related to those of Methylobacter tundripaludum were found in all soils, regardless of the incubation conditions, and they might therefore play a role in CH(4) degradation in situ. This work is providing new information supporting the potential importance of Methylobacter spp. in Arctic soils found in previous studies and contributes to the limited body of knowledge on methanotrophic activity and diversity in this extreme environment. PMID:20622133

  10. Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra

    PubMed Central

    Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique

    2013-01-01

    Arctic wildlife is often presented as being highly at risk in the face of current climate warming. We use the long-term (up to 24 years) monitoring records available on Bylot Island in the Canadian Arctic to examine temporal trends in population attributes of several terrestrial vertebrates and in primary production. Despite a warming trend (e.g. cumulative annual thawing degree-days increased by 37% and snow-melt date advanced by 4–7 days over a 23-year period), we found little evidence for changes in the phenology, abundance or productivity of several vertebrate species (snow goose, foxes, lemmings, avian predators and one passerine). Only primary production showed a response to warming (annual above-ground biomass of wetland graminoids increased by 123% during this period). We nonetheless found evidence for potential mismatches between herbivores and their food plants in response to warming as snow geese adjusted their laying date by only 3.8 days on average for a change in snow-melt of 10 days, half of the corresponding adjustment shown by the timing of plant growth (7.1 days). We discuss several reasons (duration of time series, large annual variability, amplitude of observed climate change, nonlinear dynamic or constraints imposed by various rate of warming with latitude in migrants) to explain the lack of response by herbivores and predators to climate warming at our study site. We also show how length and intensity of monitoring could affect our ability to detect temporal trends and provide recommendations for future monitoring. PMID:23836788

  11. Patterns of contamination among vascular plants exposed to local sources of polychlorinated biphenyls in the Canadian Arctic and Subarctic.

    PubMed

    Dawn Pier, M; Zeeb, Barbara A; Reimer, Kenneth J

    2002-10-01

    Polychlorinated biphenyl (PCB) concentrations were examined in 1043 Arctic vascular plant specimens comprising 31 genera and the soils they grew in. The samples were collected at 61 abandoned military and Coast Guard sites across the Canadian Arctic and Subarctic and in nine remote background locations. Genus-specific differences in PCB uptake, partitioning of PCBs among different plant tissues, and congener-specific uptake of PCBs were examined. Mean PCB concentrations and plant vs. soil regression relationships were significantly different among genera. The highest concentrations were found in Poa and Luzula and the lowest mean concentration was found in Betula. Among the genera examined, PCB concentrations in the genus Luzula exhibited the greatest increase relative to increasing soil PCB concentrations. Bioaccumulation factors were not fixed within a single genus or species, but decreased with increasing soil concentrations, suggesting that at higher levels of exposure accumulation of PCBs may be kinetically limited by redistribution processes within the plant. The accumulation of specific congeners was related to the primary mode of exposure and the octanol-air partition coefficient (K(oa)) of the congener. In plants exposed mainly to atmospheric PCBs, uptake increased with increasing K(oa), as has been reported elsewhere. By contrast, there was a negative correlation between accumulation and K(oa) in plants that were mainly exposed through direct contact with contaminated soil. Only congeners 132/153 were found at concentrations greater than predicted from their K(oa). The presence of these congeners in plants is proposed as the explanation for their predominance in terrestrial animal tissues.

  12. Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra.

    PubMed

    Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique

    2013-08-19

    Arctic wildlife is often presented as being highly at risk in the face of current climate warming. We use the long-term (up to 24 years) monitoring records available on Bylot Island in the Canadian Arctic to examine temporal trends in population attributes of several terrestrial vertebrates and in primary production. Despite a warming trend (e.g. cumulative annual thawing degree-days increased by 37% and snow-melt date advanced by 4-7 days over a 23-year period), we found little evidence for changes in the phenology, abundance or productivity of several vertebrate species (snow goose, foxes, lemmings, avian predators and one passerine). Only primary production showed a response to warming (annual above-ground biomass of wetland graminoids increased by 123% during this period). We nonetheless found evidence for potential mismatches between herbivores and their food plants in response to warming as snow geese adjusted their laying date by only 3.8 days on average for a change in snow-melt of 10 days, half of the corresponding adjustment shown by the timing of plant growth (7.1 days). We discuss several reasons (duration of time series, large annual variability, amplitude of observed climate change, nonlinear dynamic or constraints imposed by various rate of warming with latitude in migrants) to explain the lack of response by herbivores and predators to climate warming at our study site. We also show how length and intensity of monitoring could affect our ability to detect temporal trends and provide recommendations for future monitoring.

  13. Evidence of recent changes in the ice regime of lakes in the Canadian High Arctic from spaceborne satellite observations

    NASA Astrophysics Data System (ADS)

    Surdu, Cristina M.; Duguay, Claude R.; Fernández Prieto, Diego

    2016-05-01

    Arctic lakes, through their ice cover phenology, are a key indicator of climatic changes that the high-latitude environment is experiencing. In the case of lakes in the Canadian Arctic Archipelago (CAA), many of which are ice covered more than 10 months per year, warmer temperatures could result in ice regime shifts. Within the dominant polar-desert environment, small local warmer areas have been identified. These relatively small regions - polar oases - with longer growing seasons and greater biological productivity and diversity are secluded from the surrounding barren polar desert. The ice regimes of 11 lakes located in both polar-desert and polar-oasis environments, with surface areas between 4 and 542 km2, many of unknown bathymetry, were documented. In order to investigate the response of ice cover of lakes in the CAA to climate conditions during recent years, a 15-year time series (1997-2011) of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath, and Landsat acquisitions were analyzed. Results show that melt onset occurred earlier for all observed lakes. With the exception of Lower Murray Lake, all lakes experienced earlier summer ice minimum and water-clear-of-ice (WCI) dates, with greater changes being observed for polar-oasis lakes (9-24 days earlier WCI dates for lakes located in polar oases and 2-20 days earlier WCI dates for polar-desert lakes). Additionally, results suggest that some lakes may be transitioning from a perennial/multiyear to a seasonal ice regime, with only a few lakes maintaining a multiyear ice cover on occasional years. Aside Lake Hazen and Murray Lakes, which preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011.

  14. Biological and physical processes influencing sea ice, under-ice algae, and dimethylsulfoniopropionate during spring in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Galindo, V.; Levasseur, M.; Mundy, C. J.; Gosselin, M.; Tremblay, J.-É.; Scarratt, M.; Gratton, Y.; Papakiriakou, T.; Poulin, M.; Lizotte, M.

    2014-06-01

    This study presents temporal variations in concentrations of chlorophyll a (Chl a), particulate and dissolved dimethylsulfoniopropionate (DMSPp and DMSPd) in the sea ice and underlying water column in the Canadian Arctic Archipelago during the spring of 2010 and 2011. During both years, bottom ice Chl a, DMSPp and DMSPd concentrations were high (up to 1328 µg L-1, 15,082 nmol L-1, and 6110 nmol L-1, respectively) in May and decreased thereafter. The release of bottom ice algae and DMSPp in the water column was gradual in 2010 and rapid (8 days) in 2011. Bottom brine drainage during the presnowmelt period in 2010 and a rapid loss of the snow cover in 2011 coinciding with rain events explain most of the difference between the 2 years. During both years, less than 13% of the DMSPd lost from the ice was detected in the water column, suggesting a rapid microbial consumption. An under-ice diatom bloom developed in both years. In 2010, the bloom was dominated by centric diatoms while in 2011 pennates dominated, likely reflecting seeding by ice algae following the faster snowmelt progression induced by rainfall events in 2011. Both under-ice blooms were associated with high DMSPp concentrations (up to 185 nmol L-1), but pennate diatoms showed DMSPp/Chl a ratios twice higher than centrics. These results highlight the key role of snowmelt and precipitation on the temporal pattern of ice-DMSP release to the water column and on the timing, taxonomic composition, and DMSP content of phytoplankton under-ice blooms in the Arctic.

  15. Landscape and Hydrological Transformation in the Canadian High Arctic: Climate Change and Permafrost Degradation As Drivers of Change

    NASA Astrophysics Data System (ADS)

    Lamoureux, S. F.; Lafreniere, M. J.

    2014-12-01

    Recent climate warming and landscape instability arising from permafrost degradation in the Canadian High Arctic have resulted in significant changes to the hydrological system. We have undertaken an integrated watershed and permafrost research program at the Cape Bounty Arctic Watershed Observatory (75°N, 109°W) in paired watershed-lake systems to assess the impact of these changes. Research has captured hydrological changes resulting from exceptional warmth, and permafrost degradation and disturbance. Results highlight the contrasting effect of thermal (deeper soil thaw) versus physical perturbation (slope failures and permafrost degradation). Thermal perturbation applies to most of the landscape, and results indicate that ground ice melt alters flow and mobilizes solutes for a number of years following a single warm year. These effects are measureable at the slope-catchment scale, especially during baseflow. By contrast, physical disturbance is highly localized and produces high sediment and particulate carbon erosion from slopes, but downstream particulate delivery is dependent on surface connectivity. Recovery from disturbances appears to occur rapidly, and continued geomorphic change and new slope channels result in sustained delivery of particulates to channels. The result is increased long term landscape heterogeneity with respect to erosion compared to the pre-disturbance condition. Downstream channel response to particulate loading further dampens the response to physical disturbance through channel storage of material. Hence, at the larger watershed scale, the effect of physical perturbation is minimal in the initial years of recovery. These results point to a landscape that has been substantially impacted by recent hydrological and permafrost changes. Understanding and distinguishing these impacts provides a basis for systematically evaluating biogeochemical cycling and ecosystem responses in aquatic settings.

  16. Stable Isotope Probing Analysis of the Diversity and Activity of Methanotrophic Bacteria in Soils from the Canadian High Arctic

    PubMed Central

    Martineau, Christine; Whyte, Lyle G.; Greer, Charles W.

    2010-01-01

    The melting of permafrost and its potential impact on CH4 emissions are major concerns in the context of global warming. Methanotrophic bacteria have the capacity to mitigate CH4 emissions from melting permafrost. Here, we used quantitative PCR (qPCR), stable isotope probing (SIP) of DNA, denaturing gradient gel electrophoresis (DGGE) fingerprinting, and sequencing of the 16S rRNA and pmoA genes to study the activity and diversity of methanotrophic bacteria in active-layer soils from Ellesmere Island in the Canadian high Arctic. Results showed that most of the soils had the capacity to oxidize CH4 at 4°C and at room temperature (RT), but the oxidation rates were greater at RT than at 4°C and were significantly enhanced by nutrient amendment. The DGGE banding patterns associated with active methanotrophic bacterial populations were also different depending on the temperature of incubation and the addition of nutrients. Sequencing of the 16S rRNA and pmoA genes indicated a low diversity of the active methanotrophic bacteria, with all methanotroph 16S rRNA and pmoA gene sequences being related to type I methanotrophs from Methylobacter and Methylosarcina. The dominance of type I methanotrophs over type II methanotrophs in the native soil samples was confirmed by qPCR of the 16S rRNA gene with primers specific for these two groups of bacteria. The 16S rRNA and pmoA gene sequences related to those of Methylobacter tundripaludum were found in all soils, regardless of the incubation conditions, and they might therefore play a role in CH4 degradation in situ. This work is providing new information supporting the potential importance of Methylobacter spp. in Arctic soils found in previous studies and contributes to the limited body of knowledge on methanotrophic activity and diversity in this extreme environment. PMID:20622133

  17. Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra.

    PubMed

    Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique

    2013-08-19

    Arctic wildlife is often presented as being highly at risk in the face of current climate warming. We use the long-term (up to 24 years) monitoring records available on Bylot Island in the Canadian Arctic to examine temporal trends in population attributes of several terrestrial vertebrates and in primary production. Despite a warming trend (e.g. cumulative annual thawing degree-days increased by 37% and snow-melt date advanced by 4-7 days over a 23-year period), we found little evidence for changes in the phenology, abundance or productivity of several vertebrate species (snow goose, foxes, lemmings, avian predators and one passerine). Only primary production showed a response to warming (annual above-ground biomass of wetland graminoids increased by 123% during this period). We nonetheless found evidence for potential mismatches between herbivores and their food plants in response to warming as snow geese adjusted their laying date by only 3.8 days on average for a change in snow-melt of 10 days, half of the corresponding adjustment shown by the timing of plant growth (7.1 days). We discuss several reasons (duration of time series, large annual variability, amplitude of observed climate change, nonlinear dynamic or constraints imposed by various rate of warming with latitude in migrants) to explain the lack of response by herbivores and predators to climate warming at our study site. We also show how length and intensity of monitoring could affect our ability to detect temporal trends and provide recommendations for future monitoring. PMID:23836788

  18. Stable isotope probing analysis of the diversity and activity of methanotrophic bacteria in soils from the Canadian high Arctic.

    PubMed

    Martineau, Christine; Whyte, Lyle G; Greer, Charles W

    2010-09-01

    The melting of permafrost and its potential impact on CH(4) emissions are major concerns in the context of global warming. Methanotrophic bacteria have the capacity to mitigate CH(4) emissions from melting permafrost. Here, we used quantitative PCR (qPCR), stable isotope probing (SIP) of DNA, denaturing gradient gel electrophoresis (DGGE) fingerprinting, and sequencing of the 16S rRNA and pmoA genes to study the activity and diversity of methanotrophic bacteria in active-layer soils from Ellesmere Island in the Canadian high Arctic. Results showed that most of the soils had the capacity to oxidize CH(4) at 4 degrees C and at room temperature (RT), but the oxidation rates were greater at RT than at 4 degrees C and were significantly enhanced by nutrient amendment. The DGGE banding patterns associated with active methanotrophic bacterial populations were also different depending on the temperature of incubation and the addition of nutrients. Sequencing of the 16S rRNA and pmoA genes indicated a low diversity of the active methanotrophic bacteria, with all methanotroph 16S rRNA and pmoA gene sequences being related to type I methanotrophs from Methylobacter and Methylosarcina. The dominance of type I methanotrophs over type II methanotrophs in the native soil samples was confirmed by qPCR of the 16S rRNA gene with primers specific for these two groups of bacteria. The 16S rRNA and pmoA gene sequences related to those of Methylobacter tundripaludum were found in all soils, regardless of the incubation conditions, and they might therefore play a role in CH(4) degradation in situ. This work is providing new information supporting the potential importance of Methylobacter spp. in Arctic soils found in previous studies and contributes to the limited body of knowledge on methanotrophic activity and diversity in this extreme environment.

  19. New Insights into Arctic Tectonics: Uranium-Lead, (Uranium-Thorium)/Helium, and Hafnium Isotopic Data from the Franklinian Basin, Canadian Arctic Islands

    NASA Astrophysics Data System (ADS)

    Anfinson, Owen Anthony

    More than 2300 detrital zircon uranium-lead (U-Pb) ages, 32 176Hf/177Hf (eHf) isotopic values, 37 apatite helium (AHe) ages, and 72 zircon helium (ZHe) ages represent the first in-depth geochronologic and thermochronologic study of Franklinian Basin strata in the Canadian Arctic and provide new insight on >500 M.y. of geologic history along the northern Laurentian margin (modern orientation). Detrital zircon U-Pb age data demonstrate that the Franklinian Basin succession is composed of strata with three distinctly different provenance signatures. Neoproterozoic and Lower Cambrian formations contain detrital zircon populations consistent with derivation from Archean to Paleoproterozoic gneisses and granites of the west Greenland--northeast Canadian Shield. Lower Silurian to Middle Devonian strata are primarily derived from foreland basin strata of the East Greenland Caledonides (Caledonian orogen). Middle Devonian to Upper Devonian strata also contain detrital zircon populations interpreted as being primarily northerly derived from the continental landmass responsible for the Ellesmerian Orogen (often referred to as Crockerland). U-Pb age data from basal turbidites of the Middle to Upper Devonian clastic succession suggest Crockerland contributed sediment to the northern Laurentian margin by early-Middle Devonian time and that prior to the Ellesmerian Orogeny Crockerland had a comparable geologic history to the northern Baltica Craton. Detrital zircon U-Pb ages in Upper Devonian strata suggest Crockerland became the dominant source by the end of Franklinian Basin sedimentation. Mean eHf values from Paleozoic detrital zircon derived from Crockerland suggest the zircons were primarily formed in either an island arc or continental arc built on accreted oceanic crust setting. ZHe cooling ages from Middle and Upper Devonian strata were not buried deeper than 7 km since deposition and suggest Crockerland was partially exhumed during the Caledonian Orogen. AHe cooling ages

  20. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.

    PubMed

    Lescord, Gretchen L; Kidd, Karen A; Kirk, Jane L; O'Driscoll, Nelson J; Wang, Xiaowa; Muir, Derek C G

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota.

  1. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.

    PubMed

    Lescord, Gretchen L; Kidd, Karen A; Kirk, Jane L; O'Driscoll, Nelson J; Wang, Xiaowa; Muir, Derek C G

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. PMID:24909711

  2. Last Decade of Changes in Ground Temperature and Active Layer Thickness in the High Canadian Arctic and in Barrow

    NASA Astrophysics Data System (ADS)

    Romanovsky, V. E.; Cable, W.; Walker, D. A.; Yoshikawa, K.; Marchenko, S. S.

    2013-12-01

    The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Most of the permafrost observatories in the Northern Hemisphere show substantial warming of permafrost since circa 1980-1990. The magnitude of warming has varied with location, but was typically from 0.5 to 2°C. Permafrost is already thawing within the southern part of the permafrost domain. However, recent observations documented propagation of this process northward into the continuous permafrost zone. The close proximity of the exceptionally icy soil horizons to the ground surface, which is typical for the arctic tundra biome, makes tundra surfaces extremely sensitive to the natural and human-made changes that may resulted in development of processes such as thermokarst, thermal erosion, and retrogressive thaw slumps that strongly affect the stability of ecosystems and infrastructure. In 2003-2005, three Ecological Permafrost Observatories where established in the High Canadian Arctic (Green Cabin on the Banks Island, Mould Bay on the Prince Patrick Island, and Isachsen on the Ellef Ringnes Island) as a part of the University of Alaska Fairbanks NSF funded Biocomplexity Project. These observatories represent the northern part of the North American Arctic Transect (NAAT) established as a result of this project. The climatic and ground temperature data collected at these observatories show a general warming trend similar to what has been observed at the other locations in the North American Arctic. An important result of this resent warming is a significant increase in the active layer thickness (ALT) during the last decade. For example, ALT at the Isachsen observatory increased from 0.4-0.42 m in 2005 to 0.54 m in 2012. The maximum ALT of 0.58 m was recorded in 2008. In a shallow excavation across an ice wedge at the Isachsen site, we estimated that the top of the ice wedge ice was located at 42

  3. Isolation and characterization of Brachyspira spp. including "Brachyspira hampsonii" from lesser snow geese (Chen caerulescens caerulescens) in the Canadian Arctic.

    PubMed

    Rubin, Joseph E; Harms, N Jane; Fernando, Champika; Soos, Catherine; Detmer, Susan E; Harding, John C S; Hill, Janet E

    2013-11-01

    Brachyspira is associated with diarrhea and colitis in pigs, and control of these pathogens is complicated by their complex ecology. Identification of wildlife reservoirs of Brachyspira requires the discrimination of colonized animals and those simply contaminated through environmental exposure. Lesser snow geese (Chen caerulescens caerulescens) were sampled in the Canadian arctic during the summer of 2011, and cloacal swabs were cultured on selective media. Brachyspira isolates were obtained from 15/170 (8.8 %) samples, and 12/15 isolates were similar to isolates previously recovered from pigs, including "Brachyspira hampsonii", a recently characterized species associated with dysentery-like disease in pigs in North America. A pilot inoculation study with one strongly β-hemolytic B. hampsonii isolate resulted in fecal shedding of the isolate by inoculated pigs for up to 14 days post-inoculation, but no severe clinical disease. Results of this study indicate that lesser snow geese can be colonized by Brachyspira strains that can also colonize pigs. Millions of lesser snow geese (C. caerulescens caerulescens) travel through the major pork-producing areas of Canada and the USA during their annual migration, making them a potential factor in the continental distribution of these bacteria.

  4. Links between ocean properties, ice cover, and plankton dynamics on interannual time scales in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Hamilton, James M.; Collins, Kate; Prinsenberg, Simon J.

    2013-10-01

    A decade of instrumented mooring data from Barrow Strait in the eastern Canadian Arctic Archipelago reveals connections between sea ice, water characteristics, and zooplankton dynamics on interannual time scales. On the North side of the Strait, the timing of breakup is positively related to the timing of freezeup in the previous year and negatively related to spring water temperature. This suggests that an early freezeup insulates the ocean from a cold autumn atmosphere, allowing heat to be retained until spring when it contributes to early sea ice erosion. There is also a very strong negative association between the timing of freezeup and late summer salinity, suggesting that monitoring of salinity in real time could be used to predict freezeup. A zooplankton biomass index derived from acoustic Doppler current profiler echo intensity data is used to demonstrate that on the North side there are also strong connections between early summer water temperature and the start, length, and productivity of the zooplankton growth season. On the South side of the Strait where currents are stronger, the relationships seen on the North side were not observed. But here integrated zooplankton biomass index and measured currents are used to identify interannual variability in the zooplankton biomass being delivered downstream into Lancaster Sound. Also on the South side, two yearlong records of daily fluorescence profiles reveal a large difference in the phytoplankton biomass being delivered downstream between years and demonstrate a strong relationship between the timing of the spring phytoplankton bloom and that of breakup.

  5. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. /sup 18/O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter/sup -1/. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta/sup 18/O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity that suggests recent infiltration of seawater into the lake basin.

  6. Isolation and characterization of Brachyspira spp. including "Brachyspira hampsonii" from lesser snow geese (Chen caerulescens caerulescens) in the Canadian Arctic.

    PubMed

    Rubin, Joseph E; Harms, N Jane; Fernando, Champika; Soos, Catherine; Detmer, Susan E; Harding, John C S; Hill, Janet E

    2013-11-01

    Brachyspira is associated with diarrhea and colitis in pigs, and control of these pathogens is complicated by their complex ecology. Identification of wildlife reservoirs of Brachyspira requires the discrimination of colonized animals and those simply contaminated through environmental exposure. Lesser snow geese (Chen caerulescens caerulescens) were sampled in the Canadian arctic during the summer of 2011, and cloacal swabs were cultured on selective media. Brachyspira isolates were obtained from 15/170 (8.8 %) samples, and 12/15 isolates were similar to isolates previously recovered from pigs, including "Brachyspira hampsonii", a recently characterized species associated with dysentery-like disease in pigs in North America. A pilot inoculation study with one strongly β-hemolytic B. hampsonii isolate resulted in fecal shedding of the isolate by inoculated pigs for up to 14 days post-inoculation, but no severe clinical disease. Results of this study indicate that lesser snow geese can be colonized by Brachyspira strains that can also colonize pigs. Millions of lesser snow geese (C. caerulescens caerulescens) travel through the major pork-producing areas of Canada and the USA during their annual migration, making them a potential factor in the continental distribution of these bacteria. PMID:23933825

  7. Submarine debris flows and continental slople evolution in front of Quaternary ice sheets, Baffin Bay, Canadian Arctic

    SciTech Connect

    Hiscott, R.N.; Aksu, A.E. )

    1994-03-01

    Baffin Bay is a semi-enclosed extension of the Labrador Sea in the Canadian Arctic. The upper Pliocene and Quaternary successions beneath the continental slope contain important slumps and debris-flow deposits. New high-resolution single-channel seismic data have been acquired from a 500 to 600-m-deep transverse trough that indents that shelf in an area where glacial outflow was focused during the Pliocene and Pleistocene. Major shelf-edge progradation occurred both inside and on the flanks of the transverse trough. In the lower slope, several large debris flows carried proglacial deposits into the deep basin. The largest of these debris flows dramatically reshaped the sea floor by reducing bottom slopes both by proximal erosion and distal thickening of the debris-flow deposit. Subsequently, the lower slope was starved of terrigenous input, and the upper slope was steepened by accumulation of basinward thinning wedges of mass flow deposits. The processes of emplacement of large debris flows, slope reshaping, and out-of-phase accumulation identified in upper and lower slope areas of Baffin Bay are relevant to the interpretation of other line-source margins affected by major sea level falls or changes in sediment influx, including siliciclastic slope aprons and carbonate platform margins. On fans, muddy debris flows provide both a potential seal for hydrocarbons generated after burial and a potentially important mass of organic-rich mudstones that may act as source rocks in the subsurface. 32 refs., 14 figs., 1 tab.

  8. A structural fabric defined by topographic lineaments: Correlation with Tertiary deformation of Ellesmere and Axel Heiberg Islands, Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Oakey, Gordon

    1994-01-01

    Digital topographic contours from four 1:250000 scale maps have been gridded to produce a digital elevation model for part of Ellesmere and Axel Heiberg islands in the Canadian Arctic Islands. Gradient calculations were used to define both east and west dipping slopes defining a pattern of lineaments that have been compared with mapped geological structures. In ice-covered areas, where geological mapping was not possible, well-defined topographic lineaments have been identified and are correlated to extensions of major structural features. The northeast-southwest patterns of both topographic lineaments and mapped structures are strongly unimodal and support a single compressive event oriented at 67 deg west of north. This orientation is coincidental with the convergence direction calculated from the kinematic poles of rotation for Greenland relative to North America between 56 and 35 Ma. A minor secondary peak at 70 east of north is observed for thrust and normal fault solutions and is not directly related to the predicted convergence direction. Whether this represents a unique phase of deformation or is a subcomponent of a single event is not known. The agreement of structural components, lineament orientations, and convergence direction suggests an overwhelming over print of Eurekan deformation on any preexisting structural fabric. This study confirms, for the first time, an excellent compatibility between geological and geophysical constraints for the timing and geometry of the Eurekan orogeny.

  9. Microbial diversity of active layer and permafrost in an acidic wetland from the Canadian High Arctic.

    PubMed

    Wilhelm, Roland C; Niederberger, Thomas D; Greer, Charles; Whyte, Lyle G

    2011-04-01

    The abundance and structure of archaeal and bacterial communities from the active layer and the associated permafrost of a moderately acidic (pH < 5.0) High Arctic wetland (Axel Heiberg Island, Nunavut, Canada) were investigated using culture- and molecular-based methods. Aerobic viable cell counts from the active layer were ∼100-fold greater than those from the permafrost (2.5 × 10(5) CFU·(g soil dry mass)(-1)); however, a greater diversity of isolates were cultured from permafrost, as determined by 16S rRNA gene sequencing. Isolates from both layers demonstrated growth characteristics of a psychrotolerant, halotolerant, and acidotolerant community. Archaea constituted 0.1% of the total 16S rRNA gene copy number and, in the 16S rRNA gene clone library, predominantly (71% and 95%) consisted of Crenarchaeota related to Group I. 1b. In contrast, bacterial communities were diverse (Shannon's diversity index, H = ∼4), with Acidobacteria constituting the largest division of active layer clones (30%) and Actinobacteria most abundant in permafrost (28%). Direct comparisons of 16S rRNA gene sequence data highlighted significant differences between the bacterial communities of each layer, with the greatest differences occurring within Actinobacteria. Comparisons of 16S rRNA gene sequences with those from other Arctic permafrost and cold-temperature wetlands revealed commonly occurring taxa within the phyla Chloroflexi, Acidobacteria, and Actinobacteria (families Intrasporangiaceae and Rubrobacteraceae). PMID:21491982

  10. Particle-associated extracellular enzyme activity and bacterial community composition across the Canadian Arctic Ocean.

    PubMed

    Kellogg, Colleen T E; Deming, Jody W

    2014-08-01

    Microbial enzymatic hydrolysis of marine-derived particulate organic carbon (POC) can be a dominant mechanism for attenuating carbon flux in cold Arctic waters during spring and summer. Whether this mechanism depends on composition of associated microbial communities and extends into other seasons is not known. Bacterial community composition (BCC) and extracellular enzyme activity (EEA, for leucine aminopeptidases, glucosidases and chitobiases) were measured on small suspended particles and potentially sinking aggregates collected during fall from waters of the biologically productive North Water and river-impacted Beaufort Sea. Although other environmental variables appeared influential, both BCC and EEA varied along a marine productivity gradient in the two regions. Aggregates harbored the most distinctive bacterial communities, with a small number of taxa driving differences between particle-size classes (1.0-60 and > 60 μm) and free-living bacteria (0.2-1.0 μm). Significant relationships between patterns in particle-associated BCC and EEA suggest strong links between these two variables. Calculations indicated that up to 80% of POC in the euphotic zone of the North Water, and 20% in the Beaufort Sea, may be hydrolyzed enzymatically, underscoring the importance of this mechanism in attenuating carbon fluxes in Arctic waters even as winter approaches.

  11. Arctic and Offshore Research Subprogram: Reducing the uncertainties about producing oil and gas in the Alaskan Arctic

    SciTech Connect

    Not Available

    1983-10-01

    In assessing the research. The needs for the Arctic and Offshore Research (AOR) Subprogram, Morgantown Energy Technology Center with the DOE Fossil Energy Office of Oil, Gas, and Shale Technology, developed a 5-year plan that includes the following activities: (1) AOR data base development and coordination; (2) ice research; (3) seafloor soils research; and (4) subice arctic research. The DOE Arctic and Offshore Research Subprogram was initiated in FY 83, the major programming activities were performed in January and February 1983, and the program evolved to its present form by the conclusion of FY 83. The current program activities have included determining the various Arctic bibliographic data bases and initiating most pieces of the research described above (except multi-year ice properties, pipeline research, and subice feasibility studies. The seismic-measurements study continues the work initiated by the Energy Research and Development Administration, updated with an Arctic emphasis. The FY 83 accomplishments include redesigning the seafloor earthquake measurements system (SEMS) and assessing the preliminary Alaska site for potential SEMS deployment. 1 reference, 1 figure, 9 tables.

  12. Absorption and fluorescence of dissolved organic matter in the waters of the Canadian Arctic Archipelago, Baffin Bay, and the Labrador Sea

    NASA Astrophysics Data System (ADS)

    Guéguen, Céline; Cuss, Chad W.; Cassels, Chase J.; Carmack, Eddy C.

    2014-03-01

    The optical properties of dissolved organic matter (DOM) were investigated for the first time in the Canadian Arctic Archipelago (CAA), Baffin Bay (BB), and Labrador Sea (LS) as part of the International Polar Year Canada's Three Oceans project (C3O). The dynamics and composition of absorbing DOM (i.e., colored DOM, or CDOM) and fluorescent DOM (FDOM) were evaluated in several distinct water masses occupying the three regions: surface waters, Arctic outflow waters, West Greenland Intermediate waters (WGIW), upper Labrador Sea waters (uLSW), and Bottom Baffin Deep Water (BBDW). Four fluorescent components were identified by applying parallel factor analysis (PARAFAC) to 522 excitation emission matrix (EEM) spectra: three humic-like and one protein-like. The FDOM in surface waters of the CAA and BB differed considerably in character from those of the LS, with higher fluorescence intensity in the former. The fluorescence intensities of the two terrestrial humic-like components (C1 and C3) were linearly correlated with apparent oxygen utilization (AOU) in the CAA Arctic outflow and the WGIW whereas only humic-like C3 was significantly correlated with AOU in uLSW. These findings suggest that the humic-like components were produced in situ as organic matter was bio-oxidized. The slopes of the linear relationship between humic-like intensity and AOU were significantly greater in the WGIW relative to the Arctic outflow waters, which implies that FDOM in the Arctic-derived deeper layer was less prone to mineralization.

  13. Metagenomic Analysis of the Bioremediation of Diesel-Contaminated Canadian High Arctic Soils

    PubMed Central

    Yergeau, Etienne; Sanschagrin, Sylvie; Beaumier, Danielle; Greer, Charles W.

    2012-01-01

    As human activity in the Arctic increases, so does the risk of hydrocarbon pollution events. On site bioremediation of contaminated soil is the only feasible clean up solution in these remote areas, but degradation rates vary widely between bioremediation treatments. Most previous studies have focused on the feasibility of on site clean-up and very little attention has been given to the microbial and functional communities involved and their ecology. Here, we ask the question: which microorganisms and functional genes are abundant and active during hydrocarbon degradation at cold temperature? To answer this question, we sequenced the soil metagenome of an ongoing bioremediation project in Alert, Canada through a time course. We also used reverse-transcriptase real-time PCR (RT-qPCR) to quantify the expression of several hydrocarbon-degrading genes. Pseudomonas species appeared as the most abundant organisms in Alert soils right after contamination with diesel and excavation (t = 0) and one month after the start of the bioremediation treatment (t = 1m), when degradation rates were at their highest, but decreased after one year (t = 1y), when residual soil hydrocarbons were almost depleted. This trend was also reflected in hydrocarbon degrading genes, which were mainly affiliated with Gammaproteobacteria at t = 0 and t = 1m and with Alphaproteobacteria and Actinobacteria at t = 1y. RT-qPCR assays confirmed that Pseudomonas and Rhodococcus species actively expressed hydrocarbon degradation genes in Arctic biopile soils. Taken together, these results indicated that biopile treatment leads to major shifts in soil microbial communities, favoring aerobic bacteria that can degrade hydrocarbons. PMID:22253877

  14. Metagenomic analysis of the bioremediation of diesel-contaminated Canadian high arctic soils.

    PubMed

    Yergeau, Etienne; Sanschagrin, Sylvie; Beaumier, Danielle; Greer, Charles W

    2012-01-01

    As human activity in the Arctic increases, so does the risk of hydrocarbon pollution events. On site bioremediation of contaminated soil is the only feasible clean up solution in these remote areas, but degradation rates vary widely between bioremediation treatments. Most previous studies have focused on the feasibility of on site clean-up and very little attention has been given to the microbial and functional communities involved and their ecology. Here, we ask the question: which microorganisms and functional genes are abundant and active during hydrocarbon degradation at cold temperature? To answer this question, we sequenced the soil metagenome of an ongoing bioremediation project in Alert, Canada through a time course. We also used reverse-transcriptase real-time PCR (RT-qPCR) to quantify the expression of several hydrocarbon-degrading genes. Pseudomonas species appeared as the most abundant organisms in Alert soils right after contamination with diesel and excavation (t = 0) and one month after the start of the bioremediation treatment (t = 1m), when degradation rates were at their highest, but decreased after one year (t = 1y), when residual soil hydrocarbons were almost depleted. This trend was also reflected in hydrocarbon degrading genes, which were mainly affiliated with Gammaproteobacteria at t = 0 and t = 1m and with Alphaproteobacteria and Actinobacteria at t = 1y. RT-qPCR assays confirmed that Pseudomonas and Rhodococcus species actively expressed hydrocarbon degradation genes in Arctic biopile soils. Taken together, these results indicated that biopile treatment leads to major shifts in soil microbial communities, favoring aerobic bacteria that can degrade hydrocarbons.

  15. Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker Amundsen from the Polar 6 aircraft platform

    NASA Astrophysics Data System (ADS)

    Aliabadi, Amir A.; Thomas, Jennie L.; Herber, Andreas B.; Staebler, Ralf M.; Leaitch, W. Richard; Schulz, Hannes; Law, Kathy S.; Marelle, Louis; Burkart, Julia; Willis, Megan D.; Bozem, Heiko; Hoor, Peter M.; Köllner, Franziska; Schneider, Johannes; Levasseur, Maurice; Abbatt, Jonathan P. D.

    2016-06-01

    Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior

  16. A case study of old-ice import and export through Peary and Sverdrup Channels in the Canadian Arctic Archipelago: 1998-2005

    NASA Astrophysics Data System (ADS)

    Alt, Bea; Wilson, Katherine; Carrières, Tom

    This case study attempts to quantify the amount and timing of the import, export and through-flow of old ice in the Peary Channel-Sverdrup Channel area of the northern Canadian Arctic Archipelago during the period 1998-2005. The study combines quantitative weekly area-averaged ice coverage evaluations from the Canadian Ice Service (CIS) Digital Archive with detailed analysis of RADARSAT imagery and ice-motion results from the CIS ice-motion algorithm. The results show that in 1998 more than 70% of the old ice in Peary-Sverdrup was lost, half by melt and export to the south and the other half by export north into the Arctic Ocean, and that no Arctic Ocean old ice was imported into Peary-Sverdrup. A net import of 10% old ice was seen in 1999, with some indication of through-flow into southern channels. In 2000, no net import of old ice occurred in Peary-Sverdrup, but there was significant through-flow, with evidence of old ice reaching the Northwest Passage by November. Full recovery of the old-ice regime was complete by the end of 2001. More than two-thirds of the recovery was due to the in situ formation of second-year ice. Conditions in the following 3 years were near normal.

  17. Effects of shrub expansion on the hydrology of the western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Marsh, P.; Endrizzi, S.; Lantz, T. C.; Marsh, C.; Pomeroy, J. W.

    2011-12-01

    The expansion of tall (or upright) shrubs into tundra areas of the North American arctic has been documented in a few areas, and it has been suggested that this is occurring over a broad area of the arctic and will have an important impact on snow accumulation, surface energy balance, and runoff of these areas. However, there are still considerable unknowns about the details of these effects and our ability to predict future changes in hydrology. In order to help answer these questions, a detailed measurement program has been carried out at the Trail Valley Creek (TVC) research basin located approximately 50 km NE of Inuvik, NWT, Canada. This area is characterized by rolling upland tundra underlain by continuous permafrost, with a mix of tundra, shrub tundra, and forest patches. Field observations aimed at developing an improved understanding of the effect of a transition from tundra to shrub tundra has been carried out over the last 4 years. Observations at both shrub and tundra sites in the TVC basin include: meteorological observations at 3 stations; extensive end of winter snow surveys; eddy covariance observations; changes in LAI at a shrub site during the melt period; aerial photos and satellite images at frequent intervals over the melt season; winter observations of snow depth and soil temperature; aerial photo observations of changes in shrub cover; and high resolution LIDAR based measurements of elevation and vegetation height. In combination with these observations, the GEOtop hydrologic model was used to consider the interacting processes controlling snow accumulation and melt at shrub and tundra sites. Preliminary analysis demonstrates that the shrub cover has increased in the study basin over the last 32 years. At a shrub site, the shrubs were bent over and buried by snow during the winter, with increased snow depth at the shrub site compared to a tundra site. As a result, the soil temperature was higher at the shrub site both during the winter, and

  18. Changes in sea-ice phagotrophic microprotists (20 200 μm) during the spring algal bloom, Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Sime-Ngando, Télesphore; Gosselin, Michel; Juniper, S. Kim; Levasseur, Maurice

    1997-02-01

    Heterotrophic microflagellates and ciliates (i.e., 20-200 μm size fraction) were examined for evidence of their response to the spring accumulation of algal biomass in the bottom of the annual sea ice in Resolute Passage (Canadian High Arctic, ˜ 74°N, 95°W). The most abundant heterotrophic microflagellates were dinoflagellates in the water column and cryothe-comonad-type cells in the ice. Ciliates were exclusively represented by typical planktonic species in the water column while the ice community was characterized by the occurrence of benthic-type species. This contrasts with observations in the Antarctic and at the southern limit of sea ice in the northern hemisphere, where annual sea ice seems to serve as a temporary habitat for planktonic communities. Protist biomasses in Resolute Passage were one to two orders of magnitude higher in the ice than in the plankton. In the ice, a seasonal increase in the biomass of phagotrophic microprotists as well as in the number of micrometazoa (from our microprotist samples) followed the spring algal bloom. These observations (1) support previous suggestions of the existence of a functional microbial food web within sea-ice communities and (2) indicate that micrograzers may represent one of the basic levels of the ice food web that responds to the seasonal accumulation of algal biomass. Heterotrophic microprotists growing in the ice accumulated about 4 mg C m -2 d -1, a net production rate that is two to four times higher than those reported for sea-ice bacteria (both Arctic and Antarctic), and represented 1-9% of the net production of ice algea in the early season at resolute. A carbon budget exercise indicated that the required energy for microprotozoan growth in the later season, when algal biomass was declining, corresponded to 1-8% of the net biomass loss from the ice algal populations. The specific growth rates of microprotozoan populations within the ice (0.04-0.18 d -1) appeared to increase significantly with

  19. Regional variation in radionuclide concentrations and radiation dose in caribou (Rangifer tarandus) in the Canadian Arctic; 1992-94.

    PubMed

    Macdonald, C R; Ewing, L L; Elkin, B T; Wiewel, A M

    1996-04-01

    Gamma-emitting radionuclides and 210Po, an alpha-emitting product of the 238U decay chain, were analysed in tissues from 16 caribou (Rangifer tarandus) collections in the Canadian North between 1992 and 1994. The study was conducted to determine the regional variability of anthropogenic and natural radionuclides in Canadian caribou, and to estimate the background radiation dose to caribou tissues. 137Cs, 40K, 210Pb and 210Po were consistently found in most herds. Mean muscle 137Cs varied from below detection limits on Banks Island to 231 Bq kg-1 wet weight (ww) in the Beverly herd in the central Arctic. Comparison of 1992-94 levels with published values from the 1960s and 1980s showed that 137Cs in caribou is declining with an effective half-life (Teff) of 9.9 years. The highest mean bone and liver 210Pb activities were observed on south Baffin Island, which included one bone sample with 3800 Bq kg-1 ww of 210Pb and 3070 Bq kg-1 ww of 210Po. The distribution of 137Cs and 210Pb between herds was attributed to higher atmospheric deposition rates between 60 and 65 degrees N, and changes in plant community structure and lichen species composition. The highest mean absorbed dose (30 mGy year-1) was observed in 1993 in the liver of caribou from Lake Harbour. This dose translated into a weighted absorbed dose of 300 mGy year-1, assuming a radiation weighting factor (wR) of 10 to account for the increased biological efficiency of alpha particles for deterministic effects. The Lake Harbour site also had the highest individual weighted absorbed dose in bone (810 mGy year-1) and liver (530 mGy year-1) in the study. There was no significant relationship between bone 210Pb activity and age for individual or pooled herds, indicating that the estimated doses are probably present throughout the lifetime of the caribou. Because some herds number several hundred thousand individuals, collective doses may also be very high. As yet, there have been no reports of observable effects due

  20. Submarine groundwater discharge as a possible formation mechanism for permafrost-associated gas hydrate on the circum-Arctic continental shelf

    NASA Astrophysics Data System (ADS)

    Frederick, Jennifer M.; Buffett, Bruce A.

    2016-03-01

    Submarine groundwater discharge (SGD) is a large-scale, buoyancy-driven, offshore flow of terrestrial groundwater. If SGD occurs within the permafrost-bearing sediments of the circum-Arctic shelf, such fluid circulation may transport large amounts of dissolved methane to the circum-Arctic shelf, aiding the formation of permafrost-associated gas hydrate. We investigate the feasibility of this new permafrost-associated gas hydrate formation mechanism with a 2-D, multiphase fluid flow model, using the Canadian Beaufort Shelf as an example. The numerical model includes freeze/thaw permafrost processes and predicts the unsteady, 2-D methane solubility field for hydrate inventory calculations. Model results show that widespread, low-saturation hydrate deposits accumulate within and below submarine permafrost, even if offshore-flowing groundwater is undersaturated in methane gas. While intrapermafrost hydrate inventory varies widely depending on permafrost extent, subpermafrost hydrate stability remains largely intact across consecutive glacial cycles, allowing widespread subpermafrost accumulation over time. Methane gas escape to the sediment surface (atmosphere) is predicted along the seaward permafrost boundary during the early to middle years of each glacial epoch; however, if free gas is trapped within the forming permafrost layer instead, venting may be delayed until ocean transgression deepens the permafrost table during interglacial periods, and may be related to the spatial distribution of observed pingo-like features (PLFs) on the Canadian Beaufort Shelf. Shallow, gas-charged sediments are predicted above the gas hydrate stability zone at the midshelf to shelf edge and the upper slope, where a gap in hydrate stability allows free gas to accumulate and numerous PLFs have been observed.

  1. Pressure-temperature conditions in granulite facies rocks of the northern Canadian Shield, Arctic Canada

    SciTech Connect

    Frisch, T.

    1985-01-01

    The northernmost part of the Churchill Structural Province of the Canadian Shield, underlying 60,000 km/sup 2/ of southeastern Ellesmere Island, Coburg Island and eastern Devon Island, consists of granulite facies metasedimentary, meta-igneous and plutonic intrusive rocks 2400 to 1900 m.y. old. Garnet+pyroxene+plagioclase of quartzofeldspathic gneisses from Ellesmere and Coburg islands indicate pressures, at 750/sup 0/C, ranging from greater than or equal to 6 to approx. 4kb; the lower pressures are derived largely, but not solely, from rim compositions. Similar rocks from Devon Island consistently indicate higher pressures of 6 to 7 kb. Garnet and plagioclase cores in sillimanite+cordierite-rich pelitic gneisses give pressures between 5 and 6.5 kb at 750/sup 0/C, the highest pressures being found in Devon Island rocks. Orthopyroxene+cordierite symplectites around garnet in magnesian metapelites indicate pressures under 4 kb at 650/sup 0/C. All cordierite is clearly of retrograde origin, having formed as a result of decompression during uplift, but even the highest pressures determined fall below the stability limit of cordierite in metapelites. Circumstantial evidence exists for the former stable coexistence of orthopyroxene+sillimanite, which would attest to pressures well in excess of 7 kb, but existing geobarometric equilibria have been strongly influenced by retrograde processes. Retrograde pressure-temperature conditions may well predominate in many granulite terranes but are not always recognized due to a scarcity of suitable mineral assemblages.

  2. The annual cycle of particulate organic carbon export in Franklin Bay (Canadian Arctic): Environmental control and food web implications

    NASA Astrophysics Data System (ADS)

    Forest, Alexandre; Sampei, Makoto; Makabe, Ryosuke; Sasaki, Hiroshi; Barber, David G.; Gratton, Yves; Wassmann, Paul; Fortier, Louis

    2008-03-01

    As part of the Canadian Arctic Shelf Exchange Study (CASES), we assessed the importance of new production and resuspension in determining the nature and magnitude of the deep (210 m) particulate organic carbon (POC) flux from October 2003 to September 2004 in central Franklin Bay. In spring and summer, phytoplankton production was nutrient-limited in the stratified surface layer and the initial spring bloom evolved into a subsurface chlorophyll maximum (SCM) at the nutricline. Large herbivorous calanoid copepods intercepted little of the initial bloom but grazed intensely on the SCM. The phytoplankton and fecal pellet fluxes culminated simultaneously in July-August (24 and 23 mg C m-2 d-1, respectively). The detrital POC flux peaked in September (52 mg C m-2 d-1), coincident with wind-induced resuspension of recently settled POC. In the fall, detrital POC fluxes increased again to 22 mg C m-2 d-1, following the off-shelf transport of terrigenous POC carried by the Mackenzie River plume and POC resuspended by wind on the shelf. In winter, the relatively weak POC fluxes (2-7 mg C m-2 d-1, detrital at 90%) resulted from the settling down of resuspended sediments. We propose a conceptual model in which the ecosystem of Franklin Bay shifts from an algal to a detrital mode according to seasonal changes in the relative importance of fresh and old POC supplies. On the basis of this model, the ecosystem of southeastern Beaufort Sea could evolve toward a less productive equilibrium dominated by sediment resuspension in response to the ongoing reduction of the ice cover.

  3. Levels and trends of organochlorines and brominated flame retardants in ivory gull eggs from the Canadian Arctic, 1976 to 2004.

    PubMed

    Braune, Birgit M; Mallory, Mark L; Grant Gilchrist, H; Letcher, Robert J; Drouillard, Ken G

    2007-06-01

    The ivory gull (Pagophila eburnea) is a circumpolar marine bird which has recently been listed as an endangered species in Canada. To determine whether contaminants may be playing a role in the population decline of this species, ivory gull eggs collected in 1976, 1987 and 2004 from Seymour Island in the Canadian Arctic were analyzed for organochlorines, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs. This study also provides the first account of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and polybrominated biphenyls (PBBs) in ivory gulls. The most quantitatively abundant legacy organochlorines found in the ivory gull eggs were p,p'-DDE, SigmaPCB and oxychlordane. Concentrations of the organochlorines analyzed either decreased or showed little change between 1976 and 2004. Concentrations of SigmaPCDD in ivory gull eggs were greater than SigmaPCDF, and the non-ortho PCBs (primarily PCB-126) contributed the largest fraction to the total TEQ value in all years sampled. Concentrations of PCDDs, PCDFs and SigmaTEQ decreased from 1976 to 2004. In contrast, concentrations of the PBDEs steadily increased between 1976 and 2004 driven primarily by increases in BDE-47. Although concentrations of the persistent chlorinated compounds (i.e. organochlorine pesticides, PCBs, PCDDs, PCDFs) reported in this study were below published toxicological threshold values for eggs of wild birds, we cannot rule out the possibility of synergistic/additive, sublethal effects. Very few studies have been carried out to evaluate the exposure-effect relationship of the persistent brominated compounds in avian species. Given the scarcity of information on toxicity threshold levels for PBBs and PBDEs in avian species, coupled with the trend toward increasing concentrations in ivory gulls, continued monitoring and further toxicological studies of these compounds are warranted.

  4. Heavy metals and essential elements in livers of the polar bear (Ursus maritimus) in the Canadian Arctic.

    PubMed

    Norstrom, R J; Schweinsberg, R E; Collins, B T

    1986-02-01

    Polar bear (Ursus maritimus) livers (67) from six Management Zones in the western and central Canadian Arctic were analysed for 22 elements. Several, Ba, Be, Co, Mo, Ti, V and Zr, were near the detection limit in all cases. Baseline data were obtained for the remaining elements, Ag, As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, P, Se, Sr and Zn. No statistically significant effect of age, sex or geographical location was found for any of the elements, except Cd, Hg and Se, for which age and geographical location effects were found. The frequency distribution of Zn levels was bimodal. The second peak in the distribution appeared to be related to elevated levels of Cu. The average level of Cu was 104 mg kg-1 (dry wt.), higher than other marine mammals. Average levels of Cd were significantly higher in the eastern zones, but were always less than 1.0 mg kg-1 (dry wt.), significantly lower than their prey species. This may be due to the preference of polar bears for eating seal skin and fat which is low in Cd. Mercury levels tended to be higher in the western zones bordering the Beaufort Sea, which may be related to a higher proportion of bearded seal in their diet. Mean Hg levels ranged from 20 mg kg-1 in the eastern zones were related to age by the expression: Hg (mg kg-1 dry wt.) = 15.7 + 8.0 Age (years). Mercury levels in the most northerly zone near Melville Island were very high: Hg (mg kg-1 dry wt.) = 18.4 + 27.5 Age (years). Levels of Hg and Se were very highly correlated, with a molar ratio of 1.27:1, Hg/Se.

  5. Levels and trends of organochlorines and brominated flame retardants in ivory gull eggs from the Canadian Arctic, 1976 to 2004.

    PubMed

    Braune, Birgit M; Mallory, Mark L; Grant Gilchrist, H; Letcher, Robert J; Drouillard, Ken G

    2007-06-01

    The ivory gull (Pagophila eburnea) is a circumpolar marine bird which has recently been listed as an endangered species in Canada. To determine whether contaminants may be playing a role in the population decline of this species, ivory gull eggs collected in 1976, 1987 and 2004 from Seymour Island in the Canadian Arctic were analyzed for organochlorines, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs. This study also provides the first account of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and polybrominated biphenyls (PBBs) in ivory gulls. The most quantitatively abundant legacy organochlorines found in the ivory gull eggs were p,p'-DDE, SigmaPCB and oxychlordane. Concentrations of the organochlorines analyzed either decreased or showed little change between 1976 and 2004. Concentrations of SigmaPCDD in ivory gull eggs were greater than SigmaPCDF, and the non-ortho PCBs (primarily PCB-126) contributed the largest fraction to the total TEQ value in all years sampled. Concentrations of PCDDs, PCDFs and SigmaTEQ decreased from 1976 to 2004. In contrast, concentrations of the PBDEs steadily increased between 1976 and 2004 driven primarily by increases in BDE-47. Although concentrations of the persistent chlorinated compounds (i.e. organochlorine pesticides, PCBs, PCDDs, PCDFs) reported in this study were below published toxicological threshold values for eggs of wild birds, we cannot rule out the possibility of synergistic/additive, sublethal effects. Very few studies have been carried out to evaluate the exposure-effect relationship of the persistent brominated compounds in avian species. Given the scarcity of information on toxicity threshold levels for PBBs and PBDEs in avian species, coupled with the trend toward increasing concentrations in ivory gulls, continued monitoring and further toxicological studies of these compounds are warranted. PMID:17412396

  6. Virgibacillus arcticus sp. nov., a moderately halophilic, endospore-forming bacterium from permafrost in the Canadian high Arctic.

    PubMed

    Niederberger, Thomas D; Steven, Blaire; Charvet, Sophie; Barbier, Beatrice; Whyte, Lyle G

    2009-09-01

    A novel, moderately halophilic, endospore-forming bacterial strain, designated Hal 1T, was isolated from a permafrost core collected from the Canadian high Arctic. The temperature for growth of strain Hal 1T was 0-30 degrees C with no growth observed at either -5 or 37 degrees C (optimum growth at about 25 degrees C). Strain Hal 1T was able to grow at NaCl concentrations of 0-20% (w/v) and did not have an absolute NaCl requirement for growth; optimal growth was at 5% (w/v) NaCl. The level of 16S rRNA gene sequence similarity between strain Hal 1T and the type strains of Virgibacillus carmonensis and Virgibacillus necropolis was 98.2%; values with respect to the type strains of other recognized Virgibacillus species were below 96.0%. The DNA G+C content of strain Hal 1T was 38.2 mol%. Levels of DNA-DNA relatedness between strain Hal 1T and the type strains of V. carmonensis and V. necropolis were 14.0 and 21.0%, respectively. The major fatty acid of strain Hal 1T was anteiso-C15:0, consistent with species of the genus Virgibacillus. The cell-wall peptidoglycan of strain Hal 1T was type A1alpha and the major respiratory quinone was MK-7. On the basis of genotypic and physiological results, strain Hal 1T (=DSM 19574T=JCM 14839T) is proposed as the type strain of a novel species of the genus Virgibacillus, namely Virgibacillus arcticus sp. nov. PMID:19605723

  7. Buried glacier ice in permafrost, a window to the past: examples from Bylot Island, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Fortier, D.; Coulombe, S.; Kanevskiy, M. Z.; Paquette, M.; Shur, Y.; Stephani, E.

    2011-12-01

    Bylot Island is located north of Baffin Island (73°N, 80°W) and is extensively covered by an ice cap and its outlet glaciers flowing towards the arctic lowland of the Lancaster formation. During summers of 2009 and 2011 several active-layer detachment slides exposed large massive ice bodies and other types of debris-rich ice that were interpreted as buried glacier ice. The upper part of the massive ice and debris-rich ice were usually in contact with various types of ice-contact or glacio-fluvial sediments and in some cases they were covered by mass wasting/colluvial deposits. This suggests that their preservation was likely related to burial of the ice and refreezing of the overlying sediments following permafrost aggradation. A preliminary analysis of the ice facies and ice crystals revealed the presence of four distinct types of ice: 1) clear-ice bodies with very few sediment and no organic inclusions. The ice crystals were large (cm), randomly oriented and air bubbles were observed at the junction of crystals. These characteristics could potentially indicate an englacial (snow-neve metamorphism) origin for these clear ice bodies; 2) large, meter thick, clear ice layers with no sediment, nor organics. The ice crystals were large (cm), several cm long, oriented in the same direction, and vertically aligned. These characteristics could potentially point to water that refroze in a tunnel incised in englacial ice; 3) Successive, mm to cm thick, ice layers, separated by undulating sand and gravel bands also containing cobles to boulder size rock fragments. These characteristics could potentially represent regelation ice formed at the base of glaciers and incorporated to the glacier sole; 4) mm to cm suspended aggregate of fine-grained sediments in clear ice. These micro-suspended and suspended cryostructures were sometimes deformed and aligned in the form of thin (mm) undulating layers. These micro-structures were very similar to basal ice facies, presumably

  8. The application of ERTS imagery to monitoring Arctic sea ice. [mapping ice in Bering Sea, Beaufort Sea, Canadian Archipelago, and Greenland Sea

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (Principal Investigator); Bowley, C. J.

    1974-01-01

    The author has identified the following significant results. Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS-1 imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft. The results of the investigation demonstrate that ERTS-1 imagery has substantial practical application for monitoring arctic sea ice. Ice features as small as 80-100 m in width can be detected, and the combined use of the visible and near-IR imagery is a powerful tool for identifying ice types. Sequential ERTS-1 observations at high latitudes enable ice deformations and movements to be mapped. Ice conditions in the Bering Sea during early March depicted in ERTS-1 images are in close agreement with aerial ice observations and photographs.

  9. 2009 Arctic Mars Analogue Svalbard Expedition (AMASE) Evolved Gas Studies

    NASA Astrophysics Data System (ADS)

    Mahaffy, P. R.; McAdam, A.; Eigenbrode, J.; Steele, A.

    2009-12-01

    The Arctic Mars Analogue Svalbard Expedition (AMASE) continued its multi-year campaign in August 2009 to study selected sedimentary and igneous environments in this geological diverse archipelago using a variety of measurement techniques and protocols that are candidates for future Mars missions. The X-ray diffraction mineralogical and evolved gas analysis (EGA) employed during the AMASE-2009 campaign closely mimicked similar experiments that are planned for the 2011 Mars Science Laboratory (MSL). Field instruments similar to those under development for the ESA ExoMars or other rover missions provided imaging, spectroscopic, and subsurface sounding data. A variety of microbiology and field life detection techniques rounded out the AMASE-2009 analytical tools. The evolved gas mass spectrometer utilized on AMASE-2009 was designed to model elements of the Sample Analysis at Mars (SAM) suite of instruments on MSL. Powdered rock samples were heated from ambient to 1000 C in a helium stream and evolved gases continuously analyzed by a mass spectrometer. A continued focus of AMASE-2009 was analysis of carbonates from the Spitsbergen Sverrefjell volcano [1]. The similarity of macromolecular carbon (MMC) associated with magnetite in carbonate globules found in an ice cave in Sverrefjell to those studied in the Mars meteorite ALH84001 has been a motivation for their intensive study. The MMC associated with these carbonates appears to have been formed abiotically [2] following the eruption of the Sverrefjell volcano into glacial ice. The AMASE-2008 EGA studies of microsampled carbonate layers are described and the ability and limitations of these in situ tools to distinguish biomarkers. [1] H. Amundsen, Nature 327, 692-695 (1987). [2] A. Steele et al., Meteoritics and Planetary Science 42, 1549-1566 (2007) Acknowledgement: Support of this work is from the NASA ASTEP program with A. Steele AMASE PI and H. Amundsen Expedition lead.

  10. Molecular analysis of bacterial communities from a Canadian high Arctic polythermal glacier

    NASA Astrophysics Data System (ADS)

    Bhatia, M.; Sharp, M.; Foght, J.

    2003-04-01

    The goal of this study is to characterize the bacterial communities beneath, on, and adjacent to a high Arctic polythermal glacier, with a view to understanding the origins of the subglacial microbial population. The study site is John Evans Glacier (JEG), Ellesmere Island, Canada. JEG is a polythermal glacier consisting of a core of ice at the pressure melting point, surrounded by an outer layer of cold ice. Basal melting and seasonal inputs of meltwater from the glacier surface provide liquid water for subglacial microbial life. Samples were collected from the subglacial, supraglacial, and proglacial environments at JEG. Subglacial samples included basal ice and water that had been stored beneath the glacier. Dry snow, wet snow, and water from supraglacial streams were collected as representatives of the supraglacial environment, which changes in character through the melt season. Sediments and algal mats were collected from an area directly in front of the glacier terminus and along a transect adjacent to the glacier to reflect the developing proglacial environment. Hydrochemical analyses were conducted to assess the role of microbial activity in biogeochemical processes. To compare the bacterial communities, molecular techniques were applied to total community DNA that was released from the samples by a physical cell disruption technique. The polymerase chain reaction (PCR) was used with bacterial-specific primers, one of which was fluorescently labeled, to amplify community 16S rDNA genes. Single digestions with the restriction enzymes HaeIII and HhaI were performed to conduct inter- and intra-community comparisons of the terminal restriction fragment length polymorphisms (tRFLPs) of the fluorescently tagged amplified 16S rDNA genes. Preliminary results indicate that although some species are present throughout the different environments, several species are unique to each particular habitat. Further study of replicate tRFLP data and statistical analyses will

  11. Chapter 9: Oil and gas resource potential north of the Arctic Circle

    USGS Publications Warehouse

    Gautier, D.L.; Bird, K.J.; Charpentier, R.R.; Grantz, A.; Houseknecht, D.W.; Klett, T.R.; Moore, T.E.; Pitman, J.K.; Schenk, C.J.; Schuenemeyer, J.H.; Sorensen, K.; Tennyson, M.E.; Valin, Z.C.; Wandrey, C.J.

    2011-01-01

    The US Geological Survey recently assessed the potential for undiscovered conventional petroleumin the Arctic. Using a new map compilation of sedimentary elements, the area north of the Arctic Circle was subdivided into 70 assessment units, 48 of which were quantitatively assessed. The Circum-Arctic Resource Appraisal (CARA) was a geologically based, probabilistic study that relied mainly on burial history analysis and analogue modelling to estimate sizes and numbers of undiscovered oil and gas accumulations. The results of the CARA suggest the Arctic is gas-prone with an estimated 770-2990 trillion cubic feet of undiscovered conventional natural gas, most of which is in Russian territory. On an energy-equivalent basis, the quantity of natural gas ismore than three times the quantity of oil and the largest undiscovered gas eld is expected to be about 10 times the size of the largest undiscovered oil eld. In addition to gas, the gas accumulationsmay contain an estimated 39 billion barrels of liquids. The South Kara Sea is themost prospective gas assessment unit, but giant gas elds containingmore than 6 trillion cubic feet of recoverable gas are possible at a 50%chance in 10 assessment units. Sixty per cent of the estimated undiscovered oil resource is in just six assessment units, of which the Alaska Platform, with 31%of the resource, is the most prospective. Overall, the Arctic is estimated to contain between 44 and 157 billion barrels of recoverable oil. Billion barrel oil elds are possible at a 50%chance in seven assessment units.Undiscovered oil resources could be signicant to the Arctic nations, but are probably not sufcient to shift the world oil balance away from the Middle East. ?? 2011 The Geological Society of London.

  12. Greenhouse Gas Exchange in Small Arctic Thaw Ponds

    NASA Astrophysics Data System (ADS)

    Laurion, I.; Bégin, P. N.; Bouchard, F.; Preskienis, V.

    2014-12-01

    Arctic lakes and ponds can represent up to one quarter of the land surface in permafrost landscapes, particularly in lowland tundra landscapes characterized by ice wedge organic polygons. Thaw ponds can be defined as the aquatic ecosystems associated to thawing of organic soils, either resulting from active layer processes and located above low-center peat polygons (hereafter low-center polygonal or LCP ponds), or resulting from thermokarst slumping above melting ice wedges linked to the accelerated degradation of permafrost (hereafter ice-wedge trough or IWT ponds). These ponds can merge together forming larger water bodies, but with relatively stable shores (hereafter merged polygonal or MPG ponds), and with limnological characteristics similar to LCP ponds. These aquatic systems are very small and shallow, and present a different physical structure than the larger thermokarst lakes, generated after years of development and land subsidence. In a glacier valley on Bylot Island, Nunavut, Canada, thermokarst and kettle lakes together represent 29% of the aquatic area, with a thermal profile resembling those of more standard arctic lakes (mixed epilimnion). The IWT ponds (44% of the area) are stratified for a large fraction of the summer despite their shallowness, while LCP and MPG ponds (27% of the area) show a more homogeneous water column. This will affect gas exchange in these diverse aquatic systems, in addition to their unique microbiota and organic carbon lability that control the production and consumption rates of greenhouse gases. The stratification in IWT ponds generates hypoxic conditions at the bottom, and together with the larger availability of organic carbon, stimulates methanogenesis and limits the mitigating action of methanotrophs. Overall, thaw ponds are largely supersaturated in methane, with IWT ponds dominating the emissions in this landscape (92% of total aquatic emissions estimated for the same valley), and they present large variations in

  13. The impact of lower sea-ice extent on Arctic greenhouse-gas exchange

    USGS Publications Warehouse

    Parmentier, Frans-Jan W.; Christensen, Torben R.; Sørensen, Lise Lotte; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.

    2013-01-01

    In September 2012, Arctic sea-ice extent plummeted to a new record low: two times lower than the 1979–2000 average. Often, record lows in sea-ice cover are hailed as an example of climate change impacts in the Arctic. Less apparent, however, are the implications of reduced sea-ice cover in the Arctic Ocean for marine–atmosphere CO2 exchange. Sea-ice decline has been connected to increasing air temperatures at high latitudes. Temperature is a key controlling factor in the terrestrial exchange of CO2 and methane, and therefore the greenhouse-gas balance of the Arctic. Despite the large potential for feedbacks, many studies do not connect the diminishing sea-ice extent with changes in the interaction of the marine and terrestrial Arctic with the atmosphere. In this Review, we assess how current understanding of the Arctic Ocean and high-latitude ecosystems can be used to predict the impact of a lower sea-ice cover on Arctic greenhouse-gas exchange.

  14. Middle Pleistocene (?) buried glacial ice on Bylot Island, Canadian Arctic Archipleago

    NASA Astrophysics Data System (ADS)

    Fortier, D.; Godin, E.; Kanevskiy, M. Z.; Allard, M.

    2009-12-01

    Bylot Island is located north of Baffin Island (73°N, 80°W). More than the half of the island is covered by an ice cap and its outlet glaciers flowing towards the arctic lowland of the Lancaster formation. The study site comprises four main stratigraphic units. Overlying the shales (Tertiary) of the Lancaster Formation (500 m a.s.l.), a diamicton (unit 1) is covered by a “fossil forest-tundra” sequence (unit 2) containing abundant remains of trees and plants (Allard et al., submitted). Paleontological correlation of extinct species and reverse to normal palomagnetism polarities suggest a Late Pliocene to Early Pleistocene age for this unit. A sequence (unit 3) of ice-contact proximal to distal glacio-fluvial sediments overlies the organic beds. Paleomagnetic analysis showed that the upper glacio-fluvial sediments were likely deposited during the Brunhes polarity chron (younger than 0.73 Ma). The uppermost unit (unit 4) consists in a lodgement till containing clasts of Paleozoic limestone erratics. Based on amino acid ratios of shells fragments in the drift, Klassen (1993) suggested that this “foreign drift” was probably deposited during an "old" Quaternary glaciation named “Baffin glaciation” During July 2009 several active-layer detachment slides at the head of large gullies exposed large massive ice bodies located at the junction between units 3 and 4. A preliminary analysis of the ice facies and ice crystals revealed the presence of two distinct types of massive ice: 1) clear-ice bodies with very few sediments and no organic inclusions. The ice crystals were large (cm) and air bubbles were observed at the junction of crystals. These characteristics could potentially indicate an englacial origin for these clear ice bodies. In some places, the ice was stratified with undulating layers of sands and gravels. These micro-structures are very similar to basal ice facies we observed at the Matanuska Glacier in Alaska. The exposed massive ice sections were

  15. Future emissions from oil, gas, and shipping activities in the Arctic

    NASA Astrophysics Data System (ADS)

    Peters, G. P.; Nilssen, T. B.; Lindholt, L.; Eide, M. S.; Glomsrød, S.; Eide, L. I.; Fuglestvedt, J. S.

    2011-02-01

    The Arctic sea-ice is retreating faster than predicted by climate models and could become ice free during summer this century. The reduced sea-ice extent may effectively "unlock" the Arctic Ocean to increased human activities such as transit shipping and expanded oil and gas production. Travel time between Europe and the north Pacific Region can be reduced by up to 50% with low sea-ice levels and the use of this route could increase substantially as the sea-ice retreats. Oil and gas activities already occur in the Arctic region and given the large undiscovered petroleum resources increased activity could be expected with reduced sea-ice. We use a detailed global energy market model and a bottom-up shipping model with a sea-ice module to construct emission inventories of Arctic shipping and petroleum activities in 2030 and 2050. The emission inventories are on a 1× 1 degree grid and cover both short-lived pollutants and ozone pre-cursors (SO2, NOx, CO, NMVOC, BC, OC) and the long-lived greenhouse gases (CO2, CH4, N2O). We find rapid growth in transit shipping due to increased profitability with the shorter transit times compensating for increased costs in traversing areas of sea-ice. Oil and gas production remains relatively stable leading to reduced emissions from emission factor improvements. The location of oil and gas production moves into locations requiring more ship transport relative to pipeline transport, leading to rapid emissions growth from oil and gas transport via ship. Our emission inventories for the Arctic region will be used as input into chemical transport, radiative transfer, and climate models to quantify the role of Arctic activities in climate change compared to similar emissions occurring outside of the Arctic region.

  16. Application of a SeaWinds/QuikSCAT sea ice melt algorithm for assessing melt dynamics in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Howell, Stephen E. L.; Tivy, Adrienne; Yackel, John J.; Scharien, Randall K.

    2006-07-01

    A remotely sensed sea ice melt algorithm utilizing SeaWinds/QuikSCAT (QuikSCAT) data is developed and applied to sea ice the Canadian Arctic Archipelago (CAA) from 2000 to 2004. The extended advanced very high resolution radiometer Polar Pathfinder (APP-x) data set is used to identify spatially coupled relationships between sea ice melt and radiative forcings. In situ data from the Collaborative Interdisciplinary Cryospheric Experiment (C-ICE) (2000, 2001, and 2002) and the Canadian Arctic Shelf Exchange Study (CASES) (2004) are used to validate APP-x data during the melt period. QuikSCAT-detected maps of melt onset, pond onset, and drainage are created from 2000 to 2004, and results indicate considerable interannual variability of melt dynamics within the CAA. In some years, melt stages are positively spatially autocorrelated, whereas other years exhibit a negative or no spatial autocorrelation. QuikSCAT-detected stages of melt are found to be influenced by interannual varying amounts and timing of radiative forcing making prediction difficult. The spatiotemporal variability of ice melt also influences the distribution of ice within the CAA. The lower-latitude regions of the CAA are shown to have accumulated increasing concentrations of multiyear ice from 2000 to 2005. This paper concludes with a discussion of the interplay between thermodynamic and dynamic sea ice processes likely to have contributed to this trend.

  17. Fate and Transport of Toxoplasma gondii Oocysts in Seasonally Snow Covered Watersheds: A Conceptual Framework from a Melting Snowpack to the Canadian Arctic Coasts

    PubMed Central

    Simon, Audrey; Poulin, Michel Bigras; Rousseau, Alain N.; Ogden, Nicholas H.

    2013-01-01

    Toxoplasma gondii is a zoonotic protozoan that causes serious illness in humans and infects animals worldwide, including the Canadian Arctic. Indeed, high prevalence of infection amongst Inuit has been recorded, possibly due to consumption of raw infected seal meat. Here we explore the hypothesis that T. gondii oocysts contaminate the coastal marine environment via surface runoff from across the boreal watershed, particularly during the snowmelt period. We propose a conceptual framework of the different processes governing the fate and transport of T. gondii oocysts from the melting snowpack to the Canadian arctic coast via the freshwater runoff. This framework identifies the feasibility of a transmission pathway of oocysts from contaminated soil to the marine environment, but also the complexity and multiplicity of mechanisms involved. In addition, the framework identifies knowledge gaps for guiding future studies on T. gondii oocysts. Furthermore, this work could be used as a tool to investigate the possible estuarine contamination by other faeces-borne pathogens transported via the spring freshet in seasonally snow covered watersheds. PMID:23478399

  18. Air-water exchange of anthropogenic and natural organohalogens on International Polar Year (IPY) expeditions in the Canadian Arctic.

    PubMed

    Wong, Fiona; Jantunen, Liisa M; Pućko, Monika; Papakyriakou, Tim; Staebler, Ralf M; Stern, Gary A; Bidleman, Terry F

    2011-02-01

    Shipboard measurements of organohalogen compounds in air and surface seawater were conducted in the Canadian Arctic in 2007-2008. Study areas included the Labrador Sea, Hudson Bay, and the southern Beaufort Sea. High volume air samples were collected at deck level (6 m), while low volume samples were taken at 1 and 15 m above the water or ice surface. Water samples were taken within 7 m. Water concentration ranges (pg L(-1)) were as follows: α-hexachlorocyclohexane (α-HCH) 465-1013, γ-HCH 150-254, hexachlorobenzene (HCB) 4.0-6.4, 2,4-dibromoanisole (DBA) 8.5-38, and 2,4,6-tribromoanisole (TBA) 4.7-163. Air concentration ranges (pg m(-3)) were as follows: α-HCH 7.5-48, γ-HCH 2.1-7.7, HCB 48-71, DBA 4.8-25, and TBA 6.4 - 39. Fugacity gradients predicted net deposition of HCB in all areas, while exchange directions varied for the other chemicals by season and locations. Net evasion of α-HCH from Hudson Bay and the Beaufort Sea during open water conditions was shown by air concentrations that averaged 14% higher at 1 m than 15 m. No significant difference between the two heights was found over ice cover. The α-HCH in air over the Beaufort Sea was racemic in winter (mean enantiomer fraction, EF = 0.504 ± 0.008) and nonracemic in late spring-early summer (mean EF = 0.476 ± 0.010). This decrease in EF was accompanied by a rise in air concentrations due to volatilization of nonracemic α-HCH from surface water (EF = 0.457 ± 0.019). Fluxes of chemicals during the southern Beaufort Sea open water season (i.e., Leg 9) were estimated using the Whitman two-film model, where volatilization fluxes are positive and deposition fluxes are negative. The means ± SD (and ranges) of net fluxes (ng m(-2) d(-1)) were as follows: α-HCH 6.8 ± 3.2 (2.7-13), γ-HCH 0.76 ± 0.40 (0.26-1.4), HCB -9.6 ± 2.7 (-6.1 to -15), DBA 1.2 ± 0.69 (0.04-2.0), and TBA 0.46 ± 1.1 ng m(-2) d(-1) (-1.6 to 2.0).

  19. Hexachlorocyclohexanes (HCHs) in the Canadian Archipelago. 2. Air-water gas exchange of alpha- and gamma-HCH.

    PubMed

    Jantunen, Liisa M; Helm, Paul A; Kylin, Henrik; Bidleman, Terry F

    2008-01-15

    Air and water were sampled in the Canadian Archipelago during summer on the Tundra Northwest 1999 (TNW-99) expedition and air was sampled at Resolute Bay (RB), Nunavut, to determine the gas exchange of alpha- and gamma-hexachlorocyclohexanes (HCHs) and the enantiomers of alpha-HCH. Air concentrations of sigmaHCH during TNW-99 and at RB were similar, averaging 55 and 53 pg m(-3), respectively. The net gas exchange direction was volatilization for alpha-HCH and near equilibrium or deposition for gamma-HCH, whereas actual fluxes depended on the fraction of open water. Enantiomer fractions, EF = (+)/[(+) + (-)] of alpha-HCH in air sampled from shipboard were significantly correlated to those in surface water for events with >90% open water, but were closer to racemic and not correlated to EFs in water for events with 0-50% open water. Levels of alpha-HCH in air at RB averaged 37 +/- 9 pg m(-3) from June to early July, and EFs were close to racemic (0.496 +/- 0.004). In mid-July the ice pack broke up around RB. From this point through August, air concentrations increased significantly to 53 +/- 5 pg m(-3), and the mean EF decreased significantly to 0.483 +/- 0.009. Air concentrations of gamma-HCH at RB did not differ significantly before (8.0 +/- 3.7 pg m(-3)) and after (6.6 +/- 0.76 pg m(-3)) ice breakup. Results show that alpha-HCH enantiomers are sensitive tracers for following the impact of ice cover loss on gas exchange in the Arctic.

  20. Paleomagnetic dating of Holocene western and eastern Canadian Arctic sediments: combined use of radiocarbon, paleomagnetic secular variation and global spherical harmonic model of the geomagnetic field

    NASA Astrophysics Data System (ADS)

    St-Onge, Guillaume; Barletta, Francesco; Ledu, David; Rochon, André; Channell, James E. T.

    2010-05-01

    Radiocarbon dating of Holocene sediments is often challenging in the Arctic due to the paucity of datable material, carbonate dissolution and an often poorly constrained reservoir correction, highlighting the need to combine 14C dating with other methods to establish robust Arctic chronologies. Here we illustrate the potential of using Holocene paleomagnetic secular variation records and a time-varying spherical harmonic model of the geomagnetic field (CALS7K.2; Korte and Constable, 2005) in conjunction with radiocarbon dating to establish or improve age models from marine sedimentary records recently recovered on board the CCGS Amundsen in the Beaufort Sea (western Canadian Arctic, core 2004-804-650PC) and Lancaster Sound (eastern Canadian Arctic, core 2004-804-009PC). For both cores, a u-channel-based paleomagnetic study reveals the presence of a strong, stable, well-defined single component magnetization (maximum angular deviation < 5°), with characteristic remanent magnetization (ChRM) inclinations varying around the expected inclination for the latitude of the sites assuming a geocentric axial dipole. For core 650PC (Beaufort Sea), an age model spanning the last ~6 000 cal BP was established from one radiocarbon age in addition to nine paleomagnetic tie points obtained by comparing the ChRM declination profiles of core 650PC and the CALS7k.2 geomagnetic model output. In order to verify the robustness of this correlation, the ChRM inclination record of core 650PC was then compared with other western North American lacustrine and volcanic Holocene paleomagnetic secular variation records. Several common magnetic inclination features are detected among all the considered records during the last ~6 000 cal BP, indicating the same geomagnetic origin as well as the consistency of the derived age model. Similarly, for core 009PC (Lancaster Sound), the initial age model consisting of 4 radiocarbon ages was improved by adding 4 paleomagnetic tie points derived by

  1. Influence of Arctic sea-ice and greenhouse gas concentration change on the West African Monsoon.

    NASA Astrophysics Data System (ADS)

    Monerie, Paul-Arthur; Oudar, Thomas; Sanchez-Gomez, Emilia; Terray, Laurent

    2016-04-01

    The Sahelian precipitation are projected to increase in the CNRM-CM5 coupled climate model due to a strengthening of the land-Sea temperature gradient, the increase in the North Atlantic temperature and the deepening of the Heat Low. Arctic Sea-Ice loss impacts the low-level atmospheric circulation through a decrease in the northward heat transport. Some authors have linked the sea-ice loss to a poleward shift of the InterTropical Convergence Zone. Within the CMIP5 models the effect of these mechanisms are not distinguishable and it is difficult to understand the effect of the Arctic sea-ice loss on the West African Monsoon so far. We performed several sensitivity experiments with the CNRM-CM5 coupled climate models by modifying the arctic sea-ice extent and/or the greenhouse gas concentration. We then investigated separately the impact of Arctic sea-ice loss and greenhouse gas concentration increases on the West African Monsoon. The increase in greenhouse gas explains the northward shift and the strengthening of the monsoon. Its effect is stronger with a sea-ice free Arctic that leads to an increase in North Atlantic temperature and in Sahelian precipitation at the end of the rainy season (September-October). We argue that the decrease in sea-ice extent, in the context of the global warming, may moistens the Sahel during the rainy season by changing the pressure, winds and moisture fluxes at low-level.

  2. Arctic Methane Hydrates: A Potential Greenhouse Gas Hazard

    NASA Astrophysics Data System (ADS)

    Light, M. P. R.; Solana, C.

    Methane is one of the most important greenhouse gases present in the atmosphere, having 20 times more warming potential than CO2 over a 100 yr period and 56 times more over a 20 yr period. The submarine arctic ice contains abundant methane trapped as hydrates below the continental shelf and its edge. The reserves in this area are estimated at more than 140 times the volume of methane in the atmosphere and, if released relatively quickly, the effects could be catastrophic. Although some authors have established that submarine hydrates will remain stable for the next 1000 yr, this estimation could change if other phenomena are taken into account. Hydrates within the continental shelf in the Arctic are more unstable because of the increase in oceanic temperatures over the last 10,000 yr. A warm (2C maximum) intermediate depth (5- 500 m) current recently detected in the Arctic basin flowing along the shelf edge will further destabilize the methane hydrates exposed there. In addition, the presence of seismic activity along the Arctic mid-ocean ridge and in the northern Alaska region, with magnitudes greater than 3.5 Richter and epicentres less than 30 km deep, could trigger slope failures where the methane hydrate is unstable, releasing huge volumes of methane into the atmosphere. Therefore, identifying those areas that are potentially unstable under these new conditions and the possibilities of reducing the hazard are a priority in our research.

  3. Physical Mechanisms Controlling Interannual and Seasonal Variations in Melt Pond Evolution on First-Year Sea Ice in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Landy, J.; Ehn, J. K.; Shields, M.; Barber, D. G.

    2014-12-01

    At the transition between spring and summer, melt ponds form and evolve at the surface of Arctic sea ice, significantly modifying energy exchanges between the ice, atmosphere and ocean. Past observations have demonstrated that the fractional coverage of melt ponds on Arctic sea ice can vary widely over the course of a melt season, between years in the same location, and between regions. Here we present two years of melt pond observations from landfast, first-year sea ice in the Canadian Arctic, and analyze which physical mechanisms were responsible for considerable interannual variations in melt pond coverage. In general, the key factors affecting pond coverage were: (1) premelt surface topography, (2) the number of drainage features in the ice and locations of drainage channels, (3) the evolution of ice temperature, and (4) the surface energy balance. Terrestrial LiDAR measurements showed that the premelt topography was rougher in 2011 than in 2012, which led to interannual variations in maximum pond coverage and hydraulic head of 20 pp and 7 cm, respectively. A change in the meltwater balance (production minus drainage) caused the ponds to spread or recede over an area that was almost 90% larger in 2012 than in 2011. The LiDAR measurements also demonstrated that premelt topography was modified due to preferential melting under meltwater drainage channels. Some melt ponds in areas of low-lying premelt topography were unexpectedly drained as the ponds became elevated above deepening channels. Although the sea ice cover was 0.35 m thinner in 2012 than in 2011, ice interior temperatures remained colder later into June, delaying a transition in ice permeability that would allow vertical meltwater drainage from ponds. This permeability transition was observed in 2011 and contributed to a significant drop in pond coverage. For more information see: Landy, J., J. Ehn, M. Shields, and D. Barber (2014), Surface and melt pond evolution on landfast first-year sea ice in the

  4. Graduate training in Earth science across borders and disciplines: ArcTrain -"Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic"

    NASA Astrophysics Data System (ADS)

    Stein, Rüdiger; Kucera, Michal; Walter, Maren; de Vernal, Anne

    2015-04-01

    Due to a complex set of feedback processes collectively known as "polar amplification", the Arctic realm is expected to experience a greater-than-average response to global climate forcing. The cascades of feedback processes that connect the Arctic cryosphere, ocean and atmosphere remain incompletely constrained by observations and theory and are difficult to simulate in climate models. Our capacity to predict the future of the region and assess the impacts of Arctic change processes on global and regional environments hinges on the availability of interdisciplinary experts with strong international experience and understanding of the science/society interface. This is the basis of the International Research Training Group "Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic - ArcTrain", which was initiated in 2013. ArcTrain aims to educate PhD students in an interdisciplinary environment that combines paleoclimatology, physical oceanography, remote sensing and glaciology with comprehensive Earth system modelling, including sea-ice and ice-sheet components. The qualification program for the PhD students includes joint supervision, mandatory research residences at partner institutions, field courses on land and on sea (Floating University), annual meetings and training workshops and a challenging structured training in expert skills and transferrable skills. Its aim is to enhance the career prospects and employability of the graduates in a challenging international job market across academic and applied sectors. ArcTrain is a collaborative project at the University of Bremen and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven. The German part of the project is designed to continue for nine years and educate three cohorts of twelve PhD students each. The Canadian partners comprise a consortium of eight universities led by the GEOTOP cluster at the Université du Québec à Montréal and including

  5. Report of the workshop on Arctic oil and gas recovery. [Offshore

    SciTech Connect

    Sackinger, W. M.

    1980-09-01

    Mission of the workshop was to identify research priorities for the technology related to Arctic offshore oil and gas production. Two working groups were formed on ice-related subjects and soil-related subjects. Instrumentation needed to accomplish some of the research objectives was also discussed. Results of a research priority allocation survey are summarized. (DLC)

  6. Tectonic Framework of the Beaufort-Mackenzie Margin, Canadian Arctic Ocean, from Integrated Deep Seismic and Potential-Field Studies

    NASA Astrophysics Data System (ADS)

    Helwig, J. A.; Bird, D. E.; Kumar, N.; Emmet, P. A.; Dinkelman, M.

    2012-12-01

    A five-year long, ION ArcticSPAN seismic survey program in the Canadian Beaufort Sea expands and elaborates the tectonic framework of the Canada Basin passive margin. The margin is clearly subdivided into three segments of different orientation and structure: 1) the overprinted Cordilleran-Beaufort Foldbelt segment trending west towards Alaska; 2) the transtensional Tuk segment trending northeast off the Tuktoyaktuk Peninsula; and 3) the extensional Banks segment trending north off Banks Island. From nearshore to 2500 m depth, over 20,000 km of 2D long-offset data were acquired and processed into 40 km deep PSDM profiles. The latest lines used special technology for shooting beneath first-year ice-covered areas, and 450 km of OBC data were acquired in the nearshore transition zone. From well control in the Mackenzie Delta area, a geological interpretation is extended into the late Jurassic to Recent passive margin stratigraphy as well as the varying underlying crust of both oceanic affinity, and Ellesmerian and Laurentian continental affinities. Major elements of a tectonic synthesis include: 1) deep profiles show the Tertiary detached Beaufort foldbelt overlies greatly extended continental and/or oceanic crust although the COB is obscured by the overprint; 2) oceanic crust with steep relief is found at the inferred junction of the extinct spreading center of the Canada Basin in the Mackenzie delta; 3) on the Tuk margin, thick Proterozoic and Paleozoic strata flanking the Laurentian craton are terminated at the COB by a transform fault system; and 4) architecture of the Banks segment includes late Jurassic rift structure, and a continent-ocean transition beneath the continental slope prism that includes gravitational folds down-dip of shallower extensional break-away faults and rollover folds in the Tertiary. Our tectonic framework is consistent with a rotational model for opening of the Canada Basin. The free air gravity field is dominated by a high

  7. Shifts in biological productivity inferred from nutrient drawdown in the southern Beaufort Sea (2003-2011) and northern Baffin Bay (1997-2011), Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Bergeron, Myriam; Tremblay, Jean-Éric

    2014-06-01

    This paper reports the first in situ evidence of change in the net biological productivity of high-latitude western Arctic seas. Estimates of seasonal drawdown for major plant nutrients show that net community production (NCP) shifted differently in two contrasted Canadian oceanographic settings. In the stratified southeast Beaufort Sea, seasonal nitrate consumption increased 1.6-fold between 2003-2004 and 2010-2011. The concomitant thickening of the nitrate-depleted layer in summer/fall implies that subsurface chlorophyll maxima now consume nutrients over a larger extent of the water column. Meanwhile, nitrate consumption in the once productive North Water Polynya declined by 65% and is now nearly on par with the oligotrophic coastal Beaufort Sea. This decline is attributed to freshening and increased stratification. Commensurate changes in silicate and phosphate drawdown in the two regions indicate that diatoms drove the spatial and temporal shifts in NCP.

  8. Holocene History of the Bering Sea Bowhead Whale ( Balaena mysticetus) in Its Beaufort Sea Summer Grounds off Southwestern Victoria Island, Western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Dyke, Arthur S.; Savelle, James M.

    2001-05-01

    The fossil remains of 43 bowhead whales were mapped on the raised beaches of western Wollaston Peninsula, Victoria Island, Canadian Arctic, near the historic summer range limit of the Bering Sea stock in the Beaufort Sea. The elevations and radiocarbon ages of the remains demonstrate that the bowhead ranged commonly into the region following the submergence of Bering Strait at ca. 10,000 14C yr B.P. until ca. 8500 14C yr B.P. During the same interval, bowheads ranged widely from the Beaufort Sea to Baffin Bay. Subsequently, no whales reached Wollaston Peninsula until ca. 1500 14C yr B.P. Late Holocene populations evidently were small, or occupations were brief, in comparison to those of the early Holocene. Although the late Holocene recurrence may relate to the expansion of pioneering Thule whalers eastward from Alaska, there are few Thule sites and limited evidence of Thule whaling in the area surveyed to support this suggestion.

  9. New challenges for the pipeline engineer in the Russian Arctic

    SciTech Connect

    Brown, R.J.

    1995-12-31

    The offshore Russian Arctic offers new challenges for the pipeline engineer, which if not properly approached can lead to astronomical development costs. With all the associated problems of life support and logistics, an unrealistic approach to the construction, and its associated excessive costs, hydrocarbon developments could well be stifled. Considerable experience with field developments in Alaska and the Canadian Arctic has shown that with innovative engineering approaches, projects can be completed which are technically viable and commercially sound. This paper provides a historical background of the offshore pipeline research and developments and discusses in detail the pipeline installation in the Canadian Arctic for Panarctic Drake 76 and the Polargas thirty-six inch main gas transmission system. With the changing of the location to the Russian Arctic, this paper discusses how these successfully developed technologies can be applied to the Russian scene.

  10. A regional approach to plant DNA barcoding provides high species resolution of sedges (Carex and Kobresia, Cyperaceae) in the Canadian Arctic Archipelago.

    PubMed

    Clerc-Blain, Jessica L E; Starr, Julian R; Bull, Roger D; Saarela, Jeffery M

    2010-01-01

    Previous research on barcoding sedges (Carex) suggested that basic searches within a global barcoding database would probably not resolve more than 60% of the world's some 2000 species. In this study, we take an alternative approach and explore the performance of plant DNA barcoding in the Carex lineage from an explicitly regional perspective. We characterize the utility of a subset of the proposed protein-coding and noncoding plastid barcoding regions (matK, rpoB, rpoC1, rbcL, atpF-atpH, psbK-psbI) for distinguishing species of Carex and Kobresia in the Canadian Arctic Archipelago, a clearly defined eco-geographical region representing 1% of the Earth's landmass. Our results show that matK resolves the greatest number of species of any single-locus (95%), and when combined in a two-locus barcode, it provides 100% species resolution in all but one combination (matK + atpFH) during unweighted pair-group method with arithmetic mean averages (UPGMA) analyses. Noncoding regions were equally or more variable than matK, but as single markers they resolve substantially fewer taxa than matK alone. When difficulties with sequencing and alignment due to microstructural variation in noncoding regions are also considered, our results support other studies in suggesting that protein-coding regions are more practical as barcoding markers. Plastid DNA barcodes are an effective identification tool for species of Carex and Kobresia in the Canadian Arctic Archipelago, a region where the number of co-existing closely related species is limited. We suggest that if a regional approach to plant DNA barcoding was applied on a global scale, it could provide a solution to the generally poor species resolution seen in previous barcoding studies.

  11. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Klimont, Z.; Eckhardt, S.; Kupiainen, K.; Shevchenko, V. P.; Kopeikin, V. M.; Novigatsky, A. N.

    2013-09-01

    Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC) with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions") which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3% of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66° N). Putting these emissions into our model, we find that flaring contributes 42% to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52% of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper). We have calculated daily residential combustion emissions using the heating degree day (HDD) concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150% higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of annual mean Arctic

  12. Measurements of Volatile Organic Compounds (Including Dimethyl Sulfide), Aerosol Particles, and CCN in the Canadian Arctic: Preliminary Results from the Summer 2014 NETCARE Expedition Aboard the CCGS Amundsen

    NASA Astrophysics Data System (ADS)

    Mungall, E. L.; Abbatt, J.; Lee, A.; Ladino Moreno, L.

    2014-12-01

    The Arctic in summer is a cloud condensation nucleus (CCN) limited environment, and the controls on aerosol number and composition, and thus cloud formation, are poorly understood. A better understanding of these controls and their consequences is required in order to understand the region's changing climate. In order to advance that understanding, during Summer 2014 we deployed instrumentation aboard the CCGS Amundsen, the Canadian research icebreaker. We participated in Legs 1a and 1b of the cruise, affording us observations in locations as varied as the Gulf of St. Lawrence, Lancaster Sound, and the Nares Strait. We collected on-line measurements with high time resolution of particle number, size and CCN activity as well as mixing ratios of volatile organic compounds (VOCs) including dimethyl sulfide, which has been implicated as an important contributor to the CCN population in the Arctic. We also attempted to directly measure air-sea fluxes of dimethyl sulfide using a high resolution time of flight mass spectrometer (HR-ToF-CIMS, Aerodyne) sampling at 10 Hz. Here, we report preliminary results from those measurements.

  13. Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic.

    PubMed

    Iverson, Samuel A; Gilchrist, H Grant; Smith, Paul A; Gaston, Anthony J; Forbes, Mark R

    2014-03-22

    Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems.

  14. Studies of the Canadian Arctic Archipelago water transport and its relationship to basin-local forcings: Results from AO-FVCOM

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Chen, Changsheng; Beardsley, Robert C.; Gao, Guoping; Lai, Zhigang; Curry, Beth; Lee, Craig M.; Lin, Huichan; Qi, Jianhua; Xu, Qichun

    2016-06-01

    A high-resolution (up to 2 km), unstructured-grid, fully coupled Arctic sea ice-ocean Finite-Volume Community Ocean Model (AO-FVCOM) was employed to simulate the flow and transport through the Canadian Arctic Archipelago (CAA) over the period 1978-2013. The model-simulated CAA outflow flux was in reasonable agreement with the flux estimated based on measurements across Davis Strait, Nares Strait, Lancaster Sound, and Jones Sounds. The model was capable of reproducing the observed interannual variability in Davis Strait and Lancaster Sound. The simulated CAA outflow transport was highly correlated with the along-strait and cross-strait sea surface height (SSH) difference. Compared with the wind forcing, the sea level pressure (SLP) played a dominant role in establishing the SSH difference and the correlation of the CAA outflow with the cross-strait SSH difference can be explained by a simple geostrophic balance. The change in the simulated CAA outflow transport through Davis Strait showed a negative correlation with the net flux through Fram Strait. This correlation was related to the variation of the spatial distribution and intensity of the slope current over the Beaufort Sea and Greenland shelves. The different basin-scale surface forcings can increase the model uncertainty in the CAA outflow flux up to 15%. The daily adjustment of the model elevation to the satellite-derived SSH in the North Atlantic region outside Fram Strait could produce a larger North Atlantic inflow through west Svalbard and weaken the outflow from the Arctic Ocean through east Greenland.

  15. Identification and determination of the dechlorination products of Dechlorane 602 in Great Lakes fish and Arctic beluga whales by gas chromatography-high resolution mass spectrometry.

    PubMed

    Shen, Li; Jobst, Karl J; Helm, Paul A; Reiner, Eric J; McCrindle, Robert; Tomy, Gregg T; Backus, Sean; Brindle, Ian D; Marvin, Chris H

    2012-11-01

    During the course of our studies of in-use chlorinated flame retardants, such as Dechlorane Plus(®) and Dechloranes 602 and 604, blubber of beluga whales from the Canadian Arctic and lake trout and whitefish from the North American Great Lakes were found to contain two novel dechlorination products of Dechlorane 602 (Dec602). The structures of these compounds were characterized by experiments performed using both gas chromatography-high resolution mass spectrometry and Fourier transform mass spectrometry with a prepared technical mixture of monohydro and dihydroDec602 derivatives. These Dec602 derivatives are analogous to the well-known monohydro and dihydro photochemical degradation products of Mirex. The ratio of the two monohydroDec602 diastereomers varied between Lake Ontario fish and those from the upper lakes, but only one isomer was found in Arctic beluga, indicating that one isomer is either more stable or more bioaccumulative. Dechlorane Plus(®), Dec603, and Dec 604 were not detected in Arctic beluga, but Dec602 and its monohydroDec602 derivative were measured in approximately equal concentrations, ranging from 25 to 300 pg/g lipid. In Great Lakes fish, concentrations of the monohydroDec602 derivatives were also close to those of Dec602, ranging from 2 to 67 ng/g lipid and were greatest in Lake Ontario. This study reports on the first measurements of dechlorane-related compounds in Arctic biota and the first detection of monohydroDec602 degradation products and their accumulation in biota.

  16. Identification and determination of the dechlorination products of Dechlorane 602 in Great Lakes fish and Arctic beluga whales by gas chromatography-high resolution mass spectrometry.

    PubMed

    Shen, Li; Jobst, Karl J; Helm, Paul A; Reiner, Eric J; McCrindle, Robert; Tomy, Gregg T; Backus, Sean; Brindle, Ian D; Marvin, Chris H

    2012-11-01

    During the course of our studies of in-use chlorinated flame retardants, such as Dechlorane Plus(®) and Dechloranes 602 and 604, blubber of beluga whales from the Canadian Arctic and lake trout and whitefish from the North American Great Lakes were found to contain two novel dechlorination products of Dechlorane 602 (Dec602). The structures of these compounds were characterized by experiments performed using both gas chromatography-high resolution mass spectrometry and Fourier transform mass spectrometry with a prepared technical mixture of monohydro and dihydroDec602 derivatives. These Dec602 derivatives are analogous to the well-known monohydro and dihydro photochemical degradation products of Mirex. The ratio of the two monohydroDec602 diastereomers varied between Lake Ontario fish and those from the upper lakes, but only one isomer was found in Arctic beluga, indicating that one isomer is either more stable or more bioaccumulative. Dechlorane Plus(®), Dec603, and Dec 604 were not detected in Arctic beluga, but Dec602 and its monohydroDec602 derivative were measured in approximately equal concentrations, ranging from 25 to 300 pg/g lipid. In Great Lakes fish, concentrations of the monohydroDec602 derivatives were also close to those of Dec602, ranging from 2 to 67 ng/g lipid and were greatest in Lake Ontario. This study reports on the first measurements of dechlorane-related compounds in Arctic biota and the first detection of monohydroDec602 degradation products and their accumulation in biota. PMID:22718042

  17. Enhanced sea-ice export from the Arctic to the GIN seas during the Younger Dryas: A "Canadian" source from radiogenic isotope signatures

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, C.; Maccali, J.; Not, C.; Poirier, A.

    2012-04-01

    The Younger Dryas (YD) cooling event and the related slowing of the Atlantic Meridional Overturning Circulation (AMOC) have been linked to a large array of processes. The most widely supported causal mechanism involves an influx of freshwater into the North Atlantic Ocean linked to a partial drainage of glacial Lake Agassiz. Recently, a northward drainage route, through the Mackenzie River outlet into the Arctic Ocean, has been suggested from land-based studies [Murton et al., Nature 464, 740-743]. Sedimentological and geochemical analysis of cores raised from Lomonosov Ridge and the Fram Strait area, yield relatively robust evidence for enhanced ice-rafting deposition -IRD- (with a 5-fold increase -) during the critical interval. At Lomonosov, the corresponding sedimentary layer (from ca. 13 to 12 ka) is marked by a pulse of detrital carbonates in the silt to sand fractions, with approximately equal amounts of calcite and dolomite, pointing towards an Arctic Canadian sediment source area [Not & Hillaire-Marcel, Nature Communication, Jan. 31, 2012]. The layer also depicts a 5 fold increase 230Th-excess, which we link to an enhanced flux of scavenging particles. At both sites, the geochemical signatures of the YD-layer, based on elemental (Zr/Al) and isotopic (Sr, Nd and Pb) data on bulk sediments and residues ensuing from the removal of exchangeable fractions (Zr/Al, Nd, Pb, Sr), are used to identify detrital sediment source areas. Whereas three major source areas variably contributed to IRD during the MIS 3-Present interval (i.e., the Russian, Canadian and Greenland margins), the YD interval singles out by strongelemental and isotopic excursions, notably a peak in radiogenic Sr, indicating prominent supplies from the Canadian end-member. This suggests enhanced sea-ice production and drifting along the BeaufordGyre, then the Trans-Polar Drift. A major drainage event along the Mackenzie outlet area, as proposed in the above reference,would be a suitable trigger for

  18. The Canadian experience in frontier environmental protection

    SciTech Connect

    Jones, G.H. )

    1991-03-01

    Early Canadian frontier exploration (from 1955 onshore and from 1966 for offshore drilling) caused insignificant public concern. The 1967-1968 Torrey Canyon Tanker and Santa Barbara disasters roused public opinion and governments. In Canada, 1969-1970 Arctic gas blowouts, a tanker disaster, and damage to the 'Manhattan' exacerbated concerns and resulted in new environmental regulatory constraints. From 1970, the Arctic Petroleum Operations Association learned to operate safely with environmental responsibility. It studied physical environment for design criteria, and the biological and human environment to ameliorate impact. APOA's research projects covered sea-ice, permafrost, sea-bottom, oil-spills, bird and mammal migration, fish habitat, food chains, oceanography, meteorology, hunters'/trappers' harvests, etc. In 1971 Eastcoast Petroleum Operators' Association and Alaska Oil and Gas Association followed APOA's cooperative research model. EPOA stressed icebergs and fisheries. Certain research was handled by the Canadian Offshore Oil Spill Research Association. By the mid-1980s these associations had undertaken $70,000,000 of environmental oriented research, with equivalent additional work by member companies on specific needs and similar sums by Federal agencies often working with industry on complementary research. The frontier associations then merged with the Canadian Petroleum Association, already active environmentally in western Canada. Working with government and informing environmental interest groups, the public, natives, and local groups, most Canadian frontier petroleum operations proceeded with minimal delay and environmental disturbance.

  19. Strategic Environmental Assessment of Greenhouse Gas Mitigation Options in the Canadian Agricultural Sector

    NASA Astrophysics Data System (ADS)

    Noble, Bram F.; Christmas, Lisa M.

    2008-01-01

    This article presents a methodological framework for strategic environmental assessment (SEA) application. The overall objective is to demonstrate SEA as a systematic and structured policy, plan, and program (PPP) decision support tool. In order to accomplish this objective, a stakeholder-based SEA application to greenhouse gas (GHG) mitigation policy options in Canadian agriculture is presented. Using a mail-out impact assessment exercise, agricultural producers and nonproducers from across the Canadian prairie region were asked to evaluate five competing GHG mitigation options against 13 valued environmental components (VECs). Data were analyzed using multi-criteria and exploratory analytical techniques. The results suggest considerable variation in perceived impacts and GHG mitigation policy preferences, suggesting that a blanket policy approach to GHG mitigation will create gainers and losers based on soil type and associate cropping and on-farm management practices. It is possible to identify a series of regional greenhouse gas mitigation programs that are robust, socially meaningful, and operationally relevant to both agricultural producers and policy decision makers. The assessment demonstrates the ability of SEA to address, in an operational sense, environmental problems that are characterized by conflicting interests and competing objectives and alternatives. A structured and systematic SEA methodology provides the necessary decision support framework for the consideration of impacts, and allows for PPPs to be assessed based on a much broader set of properties, objectives, criteria, and constraints whereas maintaining rigor and accountability in the assessment process.

  20. Strategic environmental assessment of greenhouse gas mitigation options in the Canadian agricultural sector.

    PubMed

    Noble, Bram F; Christmas, Lisa M

    2008-01-01

    This article presents a methodological framework for strategic environmental assessment (SEA) application. The overall objective is to demonstrate SEA as a systematic and structured policy, plan, and program (PPP) decision support tool. In order to accomplish this objective, a stakeholder-based SEA application to greenhouse gas (GHG) mitigation policy options in Canadian agriculture is presented. Using a mail-out impact assessment exercise, agricultural producers and nonproducers from across the Canadian prairie region were asked to evaluate five competing GHG mitigation options against 13 valued environmental components (VECs). Data were analyzed using multi-criteria and exploratory analytical techniques. The results suggest considerable variation in perceived impacts and GHG mitigation policy preferences, suggesting that a blanket policy approach to GHG mitigation will create gainers and losers based on soil type and associate cropping and on-farm management practices. It is possible to identify a series of regional greenhouse gas mitigation programs that are robust, socially meaningful, and operationally relevant to both agricultural producers and policy decision makers. The assessment demonstrates the ability of SEA to address, in an operational sense, environmental problems that are characterized by conflicting interests and competing objectives and alternatives. A structured and systematic SEA methodology provides the necessary decision support framework for the consideration of impacts, and allows for PPPs to be assessed based on a much broader set of properties, objectives, criteria, and constraints whereas maintaining rigor and accountability in the assessment process.

  1. Analysis of Oil and Gas Production in the Arctic National Wildlife Refuge

    EIA Publications

    2004-01-01

    This study analyzed the impact on future oil imports and expenditures of opening the Arctic National Wildlife Refuge (ANWR) to petroleum development. High, low, and mean ANWR oil resource case projections were compared to the Annual Energy Outlook 2004 reference case. The study also examined whether potential synergies exist in opening ANWR to petroleum development and the construction of an Alaska gas pipeline from the North Slope to the lower 48 states.

  2. Proposed oil and gas exploration within the coastal plain of the Arctic National Wildlife Refuge, Alaska

    SciTech Connect

    Not Available

    1982-11-01

    The draft environmental impact statement describes the procedures and probable effects of aerial and geological surveying for oil and gas in the coastal area of Alaska's Arctic National Wildlife Refuge. The procedures provide for the protection of caribou caving areas and the avoidance of duplication in the survey activities. Temporary disturbances from seismic surveys would interfere with wildlife breeding and migration due to changes in the habitat. The Alaska National Interest Lands Conservation Act of 1980 provides the legal mandate for environmental assessment.

  3. An application of well data in oil and gas assessment-arctic national wildlife refuge

    USGS Publications Warehouse

    Nelson, P.H.; Schenk, C.J.; Bird, K.J.

    1998-01-01

    A current assessment of oil and gas resources in the Arctic National Wildlife Refuge (ANWR) 1002 Area by the U.S. Geological Survey relies upon seismic data, geological mapping of exposures south and west of the assessment area, and exploratory wells. Information obtained from wells up to 50 km west and north of ANWR is presented. It is emphasized that the synthesis of well data with other geological and geophysical data provides a quantitative foundation for resource estimates of ANWR.

  4. Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian basin surface waters are undersaturated with respect to aragonite.

    PubMed

    Robbins, Lisa L; Wynn, Jonathan G; Lisle, John T; Yates, Kimberly K; Knorr, Paul O; Byrne, Robert H; Liu, Xuewu; Patsavas, Mark C; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ≈ 20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean's largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater. PMID:24040074

  5. Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian basin surface waters are undersaturated with respect to aragonite.

    PubMed

    Robbins, Lisa L; Wynn, Jonathan G; Lisle, John T; Yates, Kimberly K; Knorr, Paul O; Byrne, Robert H; Liu, Xuewu; Patsavas, Mark C; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ≈ 20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean's largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

  6. Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian Basin surface waters are undersaturated with respect to aragonite

    USGS Publications Warehouse

    Robbins, Lisa L.; Wynn, Jonathan G.; Lisle, John T.; Yates, Kimberly K.; Knorr, Paul O.; Byrne, Robert H.; Liu, Xuewu; Patsava, Mark C.; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ~20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean’s largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

  7. NO 2 vertical profiles retrieved from ground-based measurements during spring 1999 in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Melo, Stella M. L.; Farahani, E.; Strong, K.; Bassford, M. R.; Preston, K. E.; McLinden, C. A.

    2004-01-01

    During the 1990s, Arctic stratospheric temperatures were lower and the breakup of the Arctic vortex occurred later than has been observed in earlier decades. These cold winters have been followed by significant ozone loss. A clear identification of all the processes involved in springtime Arctic ozone depletion is complicated by the strong coupling between transport, formation of solid and liquid aerosols, and halogen activation. One of the key chemical species in the photochemistry of ozone is NO 2. As the role of NO 2 is strongly dependent on altitude, it is desirable to know not only the NO 2 total column, but also its vertical distribution. We have a portable UV-Vis grating spectrometer that was deployed at Eureka, Canada (80.1°N, 86.4°W) in spring 1999, 2000, 2001, and 2003, and at Resolute Bay, Canada (74.7°N, 94.6°W) in spring 2002. Eureka is part of the Arctic primary station of the Network for the Detection of Stratospheric Change. Among other species, the spectrometer measures stratospheric NO 2 through observation of sunlight scattered from the zenith sky during twilight. Due to the scattering geometry, the NO 2 slant column increases with solar zenith angle (SZA), making it possible to retrieve information about the vertical distribution of NO 2 from the observed slant column variation with SZA. In this paper, we use the optimal estimation technique with a formal characterization of the errors to retrieve NO 2 concentration profiles from slant column observations made at Eureka during March and April 1999. Such measurements can also be used in the validation of NO 2 profile measurements made by satellite instruments.

  8. Baseline Monitoring of the Western Arctic Ocean Estimates 20% of Canadian Basin Surface Waters Are Undersaturated with Respect to Aragonite

    PubMed Central

    Robbins, Lisa L.; Wynn, Jonathan G.; Lisle, John T.; Yates, Kimberly K.; Knorr, Paul O.; Byrne, Robert H.; Liu, Xuewu; Patsavas, Mark C.; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ∼20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean’s largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater. PMID:24040074

  9. The Impact of a Lower Sea Ice Extent on Arctic Greenhouse Gas Exchange

    NASA Astrophysics Data System (ADS)

    Parmentier, Frans-Jan W.; Christensen, Torben R.; Lotte Sørensen, Lise; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.

    2013-04-01

    Arctic sea ice extent hit a new record low in September 2012, when it fell to a level about two times lower than the 1979-2000 average. Record low sea ice extents such as these are often hailed as an obvious example of the impact of climate change on the Arctic. Less obvious, however, are the further implications of a lower sea ice extent on Arctic greenhouse gas exchange. For example, a reduction in sea ice, in consort with a lower snow cover, has been connected to higher surface temperatures in the terrestrial part of the Arctic (Screen et al., 2012). These higher temperatures and longer growing seasons have the potential to alter the CO2 balance of Arctic tundra through enhanced photosynthesis and respiration, as well as the magnitude of methane emissions. In fact, large changes are already observed in terrestrial ecosystems (Post et al., 2009), and concerns have been raised of large releases of carbon through permafrost thaw (Schuur et al., 2011). While these changes in the greenhouse gas balance of the terrestrial Arctic are described in numerous studies, a connection with a decline in sea ice extent is nonetheless seldom made. In addition to these changes on land, a lower sea ice extent also has a direct effect on the exchange of greenhouse gases between the ocean and the atmosphere. For example, due to sea ice retreat, more ocean surface remains in contact with the atmosphere, and this has been suggested to increase the oceanic uptake of CO2 (Bates et al., 2006). However, the sustainability of this increased uptake is uncertain (Cai et al., 2010), and carbon fluxes related directly to the sea ice itself add much uncertainty to the oceanic uptake of CO2 (Nomura et al., 2006; Rysgaard et al., 2007). Furthermore, significant emissions of methane from the Arctic Ocean have been observed (Kort et al., 2012; Shakhova et al., 2010), but the consequence of a lower sea ice extent thereon is still unclear. Overall, the decline in sea ice that has been seen in recent

  10. Importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic.

    PubMed

    St Pierre, K A; St Louis, V L; Kirk, J L; Lehnherr, I; Wang, S; La Farge, C

    2015-05-19

    Caribou, which rely on lichens as forage, are a dietary source of monomethylmercury (MMHg) to many of Canada's Arctic Aboriginal people. However, little is understood about the sources of MMHg to lichens in the High Arctic. We quantified MMHg, total mercury (THg) and other chemical parameters (e.g., marine and crustal elements, δ(13)C, δ(15)N, organic carbon, calcium carbonate) in lichen and soil samples collected along transects extending from the coast on Bathurst and Devon islands, Nunavut, to determine factors driving lichen MMHg and THg concentrations in the High Arctic. Lichen MMHg and THg concentrations ranged from 1.41 to 17.1 ng g(-1) and from 36.0 to 361 ng g(-1), respectively. Both were highly enriched over concentrations in underlying soils, indicating a predominately atmospheric source of Hg in lichens. However, MMHg and THg enrichment at coastal sites on Bathurst Island was far greater than on Devon Island. We suggest that this variability can be explained by the proximity of the Bathurst Island transect to several polynyas, which promote enhanced Hg deposition to adjacent landscapes through various biogeochemical processes. This study is the first to clearly show a strong marine influence on MMHg inputs to coastal terrestrial food webs with implications for MMHg accumulation in caribou and the health of the people who depend on them as part of a traditional diet.

  11. Developing strategies for automated remote plant production systems: Environmental control and monitoring of the Arthur Clarke Mars Greenhouse in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Bamsey, M.; Berinstain, A.; Graham, T.; Neron, P.; Giroux, R.; Braham, S.; Ferl, R.; Paul, A.-L.; Dixon, M.

    2009-12-01

    The Arthur Clarke Mars Greenhouse is a unique research facility dedicated to the study of greenhouse engineering and autonomous functionality under extreme operational conditions, in preparation for extraterrestrial biologically-based life support systems. The Arthur Clarke Mars Greenhouse is located at the Haughton Mars Project Research Station on Devon Island in the Canadian High Arctic. The greenhouse has been operational since 2002. Over recent years the greenhouse has served as a controlled environment facility for conducting scientific and operationally relevant plant growth investigations in an extreme environment. Since 2005 the greenhouse has seen the deployment of a refined nutrient control system, an improved imaging system capable of remote assessment of basic plant health parameters, more robust communication and power systems as well as the implementation of a distributed data acquisition system. Though several other Arctic greenhouses exist, the Arthur Clarke Mars Greenhouse is distinct in that the focus is on autonomous operation as opposed to strictly plant production. Remote control and autonomous operational experience has applications both terrestrially in production greenhouses and extraterrestrially where future long duration Moon/Mars missions will utilize biological life support systems to close the air, food and water loops. Minimizing crew time is an important goal for any space-based system. The experience gained through the remote operation of the Arthur Clarke Mars Greenhouse is providing the experience necessary to optimize future plant production systems and minimize crew time requirements. Internal greenhouse environmental data shows that the fall growth season (July-September) provides an average photosynthetic photon flux of 161.09 μmol m -2 s -1 (August) and 76.76 μmol m -2 s -1 (September) with approximately a 24 h photoperiod. The spring growth season provides an average of 327.51 μmol m -2 s -1 (May) and 339.32 μmol m -2 s

  12. Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the central Canadian Arctic.

    PubMed

    Kafle, Pratap; Lejeune, Manigandan; Verocai, Guilherme G; Hoberg, Eric P; Kutz, Susan J

    2015-12-01

    Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host-parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings.

  13. Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the central Canadian Arctic

    PubMed Central

    Kafle, Pratap; Lejeune, Manigandan; Verocai, Guilherme G.; Hoberg, Eric P.; Kutz, Susan J.

    2015-01-01

    Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host–parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings. PMID

  14. Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales.

    PubMed

    Campagna, Leonardo; Van Coeverden de Groot, Peter J; Saunders, Brenda L; Atkinson, Stephen N; Weber, Diana S; Dyck, Markus G; Boag, Peter T; Lougheed, Stephen C

    2013-09-01

    As global warming accelerates the melting of Arctic sea ice, polar bears (Ursus maritimus) must adapt to a rapidly changing landscape. This process will necessarily alter the species distribution together with population dynamics and structure. Detailed knowledge of these changes is crucial to delineating conservation priorities. Here, we sampled 361 polar bears from across the center of the Canadian Arctic Archipelago spanning the Gulf of Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites and mitochondrial control region sequences to quantify genetic differentiation, estimate gene flow, and infer population history. Two populations, roughly coincident with GB and MC, are significantly differentiated at both nuclear (F ST = 0.01) and mitochondrial (ΦST = 0.47; F ST = 0.29) loci, allowing Bayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species' range. These mtDNA differences probably reflect both genetic drift and historical colonization dynamics. In contrast, the differentiation inferred from microsatellites is only on the scale of hundreds of years, possibly reflecting contemporary impediments to gene flow. Taken together, our data suggest that gene flow is insufficient to homogenize the GB and MC populations and support the designation of GB and MC as separate polar bear conservation units. Our study also provide a striking example of how nuclear DNA and mtDNA capture different aspects of a species demographic history. PMID:24102001

  15. Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales

    PubMed Central

    Campagna, Leonardo; Van Coeverden de Groot, Peter J; Saunders, Brenda L; Atkinson, Stephen N; Weber, Diana S; Dyck, Markus G; Boag, Peter T; Lougheed, Stephen C

    2013-01-01

    As global warming accelerates the melting of Arctic sea ice, polar bears (Ursus maritimus) must adapt to a rapidly changing landscape. This process will necessarily alter the species distribution together with population dynamics and structure. Detailed knowledge of these changes is crucial to delineating conservation priorities. Here, we sampled 361 polar bears from across the center of the Canadian Arctic Archipelago spanning the Gulf of Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites and mitochondrial control region sequences to quantify genetic differentiation, estimate gene flow, and infer population history. Two populations, roughly coincident with GB and MC, are significantly differentiated at both nuclear (FST = 0.01) and mitochondrial (ΦST = 0.47; FST = 0.29) loci, allowing Bayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species’ range. These mtDNA differences probably reflect both genetic drift and historical colonization dynamics. In contrast, the differentiation inferred from microsatellites is only on the scale of hundreds of years, possibly reflecting contemporary impediments to gene flow. Taken together, our data suggest that gene flow is insufficient to homogenize the GB and MC populations and support the designation of GB and MC as separate polar bear conservation units. Our study also provide a striking example of how nuclear DNA and mtDNA capture different aspects of a species demographic history. PMID:24102001

  16. Transient sensitivities of sea ice export through the Canadian Arctic Archipelago inferred from a coupled ocean/sea-ice adjoint model

    NASA Astrophysics Data System (ADS)

    Heimbach, P.; Losch, M.; Menemenlis, D.; Campin, J.; Hill, C.

    2008-12-01

    The sensitivity of sea-ice export through the Canadian Arctic Archipelago (CAA), measured in terms of its solid freshwater export through Lancaster Sound, to changes in various elements of the ocean and sea-ice state, and to elements of the atmospheric forcing fields through time and space is assessed by means of a coupled ocean/sea-ice adjoint model. The adjoint model furnishes full spatial sensitivity maps (also known as Lagrange multipliers) of the export metric to a variety of model variables at any chosen point in time, providing the unique capability to quantify major drivers of sea-ice export variability. The underlying model is the MIT ocean general circulation model (MITgcm), which is coupled to a Hibler-type dynamic/thermodynamic sea-ice model. The configuration is based on the Arctic face of the ECCO3 high-resolution cubed-sphere model, but coarsened to 36-km horizontal grid spacing. The adjoint of the coupled system has been derived by means of automatic differentiation using the software tool TAF. Finite perturbation simulations are performed to check the information provided by the adjoint. The sea-ice model's performance in the presence of narrow straits is assessed with different sea-ice lateral boundary conditions. The adjoint sensitivity clearly exposes the role of the model trajectory and the transient nature of the problem. The complex interplay between forcing, dynamics, and boundary condition is demonstrated in the comparison between the different calculations. The study is a step towards fully coupled adjoint-based ocean/sea-ice state estimation at basin to global scales as part of the ECCO efforts.

  17. A community-based, environmental chronic disease prevention intervention to improve healthy eating psychosocial factors and behaviors in indigenous populations in the Canadian Arctic.

    PubMed

    Mead, Erin L; Gittelsohn, Joel; Roache, Cindy; Corriveau, André; Sharma, Sangita

    2013-10-01

    Diet-related chronic diseases are highly prevalent among indigenous populations in the Canadian Arctic. A community-based, multi-institutional nutritional and lifestyle intervention-Healthy Foods North-was implemented to improve food-related psychosocial factors and behaviors among Inuit and Inuvialuit in four intervention communities (with two comparison communities) in Nunavut and the Northwest Territories, Canada, in 2008. The 12-month program was developed from theory (social cognitive theory and social ecological models), formative research, and a community participatory process. It included an environmental component to increase healthy food availability in local stores and activities consisting of community-wide and point-of-purchase interactive educational taste tests and cooking demonstrations, media (e.g., radio ads, posters, shelf labels), and events held in multiple venues, including recreation centers and schools. The intervention was evaluated using pre- and postassessments with 246 adults from intervention and 133 from comparison communities (311 women, 68 men; mean age 42.4 years; 78.3% retention rate). Outcomes included psychosocial constructs (healthy eating knowledge, self-efficacy, and behavioral intentions), frequency of healthy and unhealthy food acquisition, healthiness of commonly used food preparation methods, and body mass index (kg/m(2)). After adjustment for demographic, socioeconomic status, and body mass index variables, respondents living in intervention communities showed significant improvements in food-related self-efficacy (β = 0.15, p = .003) and intentions (β = 0.16, p = .001) compared with comparison communities. More improvements from the intervention were seen in overweight, obese, and high socioeconomic status respondents. A community-based, multilevel intervention is an effective strategy to improve psychosocial factors for healthy nutritional behavior change to reduce chronic disease in indigenous Arctic populations.

  18. Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales.

    PubMed

    Campagna, Leonardo; Van Coeverden de Groot, Peter J; Saunders, Brenda L; Atkinson, Stephen N; Weber, Diana S; Dyck, Markus G; Boag, Peter T; Lougheed, Stephen C

    2013-09-01

    As global warming accelerates the melting of Arctic sea ice, polar bears (Ursus maritimus) must adapt to a rapidly changing landscape. This process will necessarily alter the species distribution together with population dynamics and structure. Detailed knowledge of these changes is crucial to delineating conservation priorities. Here, we sampled 361 polar bears from across the center of the Canadian Arctic Archipelago spanning the Gulf of Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites and mitochondrial control region sequences to quantify genetic differentiation, estimate gene flow, and infer population history. Two populations, roughly coincident with GB and MC, are significantly differentiated at both nuclear (F ST = 0.01) and mitochondrial (ΦST = 0.47; F ST = 0.29) loci, allowing Bayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species' range. These mtDNA differences probably reflect both genetic drift and historical colonization dynamics. In contrast, the differentiation inferred from microsatellites is only on the scale of hundreds of years, possibly reflecting contemporary impediments to gene flow. Taken together, our data suggest that gene flow is insufficient to homogenize the GB and MC populations and support the designation of GB and MC as separate polar bear conservation units. Our study also provide a striking example of how nuclear DNA and mtDNA capture different aspects of a species demographic history.

  19. Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the central Canadian Arctic.

    PubMed

    Kafle, Pratap; Lejeune, Manigandan; Verocai, Guilherme G; Hoberg, Eric P; Kutz, Susan J

    2015-12-01

    Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host-parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings. PMID

  20. Canopy gas exchange of white spruce in contrasting habitats near the Arctic treeline in northwest Alaska

    NASA Astrophysics Data System (ADS)

    Sullivan, P.; Mcnown, R. W.; Sveinbjornsson, B.

    2011-12-01

    Recent work near the Arctic treeline has revealed that an increasing number of white spruce are showing negative growth responses to rising air temperatures. Researchers have speculated that these negative responders are experiencing warm temperature-induced drought stress. Measurements of white spruce needle gas exchange near the Arctic treeline are rare and, to our knowledge, measurements of whole canopy gas exchange have not been made. In this study, we measured sap flow to estimate whole canopy transpiration at hourly intervals for the entire growing seasons of 2010 and 2011 in white spruce growing on a riverside terrace, in a hillslope forest and at the treeline. We used weekly measurements of needle-scale photosynthesis, transpiration and needle δ13C to estimate water use efficiency at each site. We then applied these estimates of water use efficiency to our sap flow data in order to estimate hourly whole canopy photosynthesis at each site for the two growing seasons. Our results show evidence of stomatal control when the atmospheric vapor pressure deficit exceeds approximately 1.0 kPa, but no evidence of complete stomatal closure. Trees growing on the riverside terrace, where soils are relatively warm and dry, are more efficient in their water use, have greater leaf area and assimilate more carbon per unit basal diameter than trees in the forest and at the treeline. We found that the month of September, after growth has almost completely ceased, can be an important time for carbon uptake in white spruce near the Arctic treeline.

  1. Mercury distribution in the skin of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) from the Canadian Arctic and mercury burdens and excretion by moulting.

    PubMed

    Wagemann, R; Kozlowska, H

    2005-12-01

    Beluga and narwhal skin as a whole (in Inuktitut known as "muktuk") is considered to be a delicacy by native Canadian and Greenland people. Individual strata of the skin, and muscle from 27 beluga from the western, and 20 narwhal from the eastern Canadian Arctic, were analyzed for mercury and the thickness and density of each skin layer was measured. Mercury was not uniformly distributed in the skin, but increased outwardly with each layer. The concentration was only 0.29 and 0.16 microg/g (wet wt) in the innermost layer (dermis) of belugas and narwhal respectively, and 1.5 and 1.4 microg/g (wet wt) in the outermost layer (degenerative epidermis) of beluga and narwhal, respectively. There was a significant (alpha=0.05) association between age and mercury concentration in each skin layer, the regression coefficients progressively increasing from the inner layer (dermis) to the outer layer: 0.011-0.063 microg/g year-1; 0.034 microg/g year-1 for skin as a whole; 0.054 microg/g year-1 for muscle. The concentration of total mercury was 0.84 and 0.59 microg/g (wet wt) in skin as a whole (muktuk) of beluga and narwhal respectively, and 0.12 and 0.03 microg/g in blubber, respectively. The average, total mercury concentration in muscle tissue was 1.4 and 0.81 microg/g wet wt, in beluga and narwhal respectively, exceeding (except for blubber) the Canadian Government's Guideline (0.5 microg/g wet wt) for fish export and consumption. The skin surface area of an average-size beluga and narwhal was estimated (6.10 and 6.50 m2, respectively), as were excretions of mercury through moulting (13,861 and 6721 microg year-1; 14 and 7 mg year-1) for belugas and narwhal, respectively. The whole-body mercury burden (699,300 microg; 700 mg) for a 1000 kg beluga and its various tissues were estimated, as was the fraction of mercury excreted by moulting (2-0.42% of the whole-body burden). Annual mercury burden increments in beluga skin, muscle and the whole body were estimated (2750; 17

  2. Mercury distribution in the skin of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) from the Canadian Arctic and mercury burdens and excretion by moulting.

    PubMed

    Wagemann, R; Kozlowska, H

    2005-12-01

    Beluga and narwhal skin as a whole (in Inuktitut known as "muktuk") is considered to be a delicacy by native Canadian and Greenland people. Individual strata of the skin, and muscle from 27 beluga from the western, and 20 narwhal from the eastern Canadian Arctic, were analyzed for mercury and the thickness and density of each skin layer was measured. Mercury was not uniformly distributed in the skin, but increased outwardly with each layer. The concentration was only 0.29 and 0.16 microg/g (wet wt) in the innermost layer (dermis) of belugas and narwhal respectively, and 1.5 and 1.4 microg/g (wet wt) in the outermost layer (degenerative epidermis) of beluga and narwhal, respectively. There was a significant (alpha=0.05) association between age and mercury concentration in each skin layer, the regression coefficients progressively increasing from the inner layer (dermis) to the outer layer: 0.011-0.063 microg/g year-1; 0.034 microg/g year-1 for skin as a whole; 0.054 microg/g year-1 for muscle. The concentration of total mercury was 0.84 and 0.59 microg/g (wet wt) in skin as a whole (muktuk) of beluga and narwhal respectively, and 0.12 and 0.03 microg/g in blubber, respectively. The average, total mercury concentration in muscle tissue was 1.4 and 0.81 microg/g wet wt, in beluga and narwhal respectively, exceeding (except for blubber) the Canadian Government's Guideline (0.5 microg/g wet wt) for fish export and consumption. The skin surface area of an average-size beluga and narwhal was estimated (6.10 and 6.50 m2, respectively), as were excretions of mercury through moulting (13,861 and 6721 microg year-1; 14 and 7 mg year-1) for belugas and narwhal, respectively. The whole-body mercury burden (699,300 microg; 700 mg) for a 1000 kg beluga and its various tissues were estimated, as was the fraction of mercury excreted by moulting (2-0.42% of the whole-body burden). Annual mercury burden increments in beluga skin, muscle and the whole body were estimated (2750; 17

  3. Supraglacial sulfur springs and associated biological activity in the Canadian high arctic - signs of life beneath the ice

    USGS Publications Warehouse

    Grasby, Stephen E.; Allen, Carlton C.; Longazo, Teresa G.; Lisle, John T.; Griffin, Dale W.; Beauchamp, Benoit

    2003-01-01

    Unique springs, discharging from the surface of an arctic glacier, release H2S and deposit native sulfur, gypsum, and calcite. The presence of sulfur in three oxidation states indicates a complex series of redox reactions. Physical and chemical conditions of the spring water and surrounding environment, as well as mineralogical and isotopic signatures, suggest biologically mediated reactions. Cell counts and DNA analyses confirm bacteria are present in the spring system, and a limited number of sequenced isolates suggests that complex communities of bacteria live within the glacial system.

  4. Supraglacial Sulfur Springs and Associated Biological Activity in the Canadian High Arctic-Signs of Life Beneath the Ice

    NASA Astrophysics Data System (ADS)

    Grasby, Stephen E.; Allen, Carlton C.; Longazo, Teresa G.; Lisle, John T.; Griffin, Dale W.; Beauchamp, Benoit

    2003-11-01

    Unique springs, discharging from the surface of an arctic glacier, release H2S and deposit native sulfur, gypsum, and calcite. The presence of sulfur in three oxidation states indicates a complex series of redox reactions. Physical and chemical conditions of the spring water and surrounding environment, as well as mineralogical and isotopic signatures, suggest biologically mediated reactions. Cell counts and DNA analyses confirm bacteria are present in the spring system, and a limited number of sequenced isolates suggests that complex communities of bacteria live within the glacial system.

  5. What we know, do not know, and need to know about climate change vulnerability in the western Canadian Arctic: a systematic literature review

    NASA Astrophysics Data System (ADS)

    Ford, James D.; Pearce, Tristan

    2010-01-01

    This letter systematically reviews and synthesizes scientific and gray literature publications (n = 420) to identify and characterize the nature of climate change vulnerability in the Inuvialuit Settlement Region of the western Canadian Arctic and identify gaps in understanding. The literature documents widespread evidence of climate change, with implications for human and biophysical systems. Adaptations are being employed to manage changing conditions and are indicative of a high adaptive capacity. However, barriers to adaptation are evident and are expected to constrain adaptive capacity to future climate change. Continued climate change is predicted for the region, with differential exposure sensitivity for communities, groups and sectors: a function of social-economic-biophysical characteristics and projected future climatic conditions. Existing climate risks are expected to increase in magnitude and frequency, although the interaction between projected changes and socio-economic-demographic trends has not been assessed. The capacity for adapting to future climate change has also not been studied. The review identifies the importance of targeted vulnerability research that works closely with community members and other stakeholders to address research needs. Importantly, the fully categorized list of reviewed references accompanying this letter will be a valuable resource for those working or planning to work in the region, capturing climate change research published since 1990. At a broader level, the systematic review methodology offers a promising tool for climate/environmental change studies in general where there is a large and emerging body of research but limited understanding of research gaps and needs.

  6. Tectonic Map of the Ellesmerian and Eurekan deformation belts on Svalbard, North Greenland and the Queen Elizabeth Islands (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Piepjohn, Karsten; von Gosen, Werner; Tessensohn, Franz; Reinhardt, Lutz; McClelland, William C.; Dallmann, Winfried; Gaedicke, Christoph; Harrison, Christopher

    2016-04-01

    The tectonic map presented here shows the distribution of the major post-Ellesmerian and pre-Eurekan sedimentary basins, parts of the Caledonian Orogen, the Ellesmerian Fold-and-Thrust Belt, structures of the Cenozoic Eurekan deformation, and areas affected by the Eurekan overprint. The present continental margin of North America towards the Arctic Ocean between the Queen Elizabeth Islands and Northeast Greenland and the present west margin of the Barents Shelf are characterized by the Paleozoic Ellesmerian Fold-and-Thrust Belt, the Cenozoic Eurekan deformation, and, in parts, the Caledonian Orogen. In many areas, the structural trends of the Ellesmerian and Eurekan deformations are more or less parallel, and often, structures of the Ellesmerian Orogeny are affected or reactivated by the Eurekan deformation. While the Ellesmerian Fold-and-Thrust Belt is dominated by orthogonal compression and the formation of wide fold-and-thrust zones on Ellesmere Island, North Greenland and Spitsbergen, the Eurekan deformation is characterized by a complex network of regional fold-and-thrust belts (Spitsbergen, central Ellesmere Island), large distinct thrust zones (Ellesmere Island, North Greenland) and a great number of strike-slip faults (Spitsbergen, Ellesmere Island). The Ellesmerian Fold-and-Thrust Belt was most probably related to the approach and docking of the Pearya Terrane (northernmost part of Ellesmere Island) and Spitsbergen against the north margin of Laurasia (Ellesmere Island/North Greenland) in the earliest Carboniferous. The Eurekan deformation was related to plate tectonic movements during the final break-up of Laurasia and the opening of Labrador Sea/Baffin Bay west, the Eurasian Basin north, and the Norwegian/Greenland seas east of Greenland. The tectonic map presented here shows the German contribution to the Tectonic Map of the Arctic 1:5,000,000 (TeMAr) as part of the international project "Atlas of geological maps of Circumpolar Arctic at 1

  7. Controls on Weathering of Pyrrhotite in a Low-Sulfide, Granitic Mine-Waste Rock in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Langman, J. B.; Holland, S.; Sinclair, S.; Blowes, D.

    2013-12-01

    Increased environmental risk is incurred with expansion of mineral extraction in the Arctic. A greater understanding of geochemical processes associated with hard-rock mining in this cold climate is needed to evaluate and mitigate these risks. A laboratory and in-situ experiment was conducted to examine mineral weathering and the generation of acid rock drainage in a low-sulfide, run-of-mine waste rock in an Arctic climate. Rock with different concentrations of sulfides (primarily pyrrhotite [Fe7S8] containing small amounts of Co and Ni) and carbonates were weathered in the laboratory and in-situ, large-scale test piles to examine leachate composition and mineral weathering. The relatively larger sulfide-containing rock produced sufficient acid to overcome carbonate buffering and produced a declining pH environment with concomitant release of SO4, Fe, Co, and Ni. Following carbonate consumption, aluminosilicate buffering stabilized the pH above 4 until a reduction in acid generation. Results from the laboratory experiment assisted in determining that after consumption of 1.6 percent of the total sulfide, the larger sulfide-concentration test pile likely is at an internal steady-state or maximal weathering rate after seven years of precipitation input and weathering that is controlled by an annual freeze-thaw cycle. Further weathering of the test pile should be driven by external factors of temperature and precipitation in this Arctic, semi-arid region instead of internal factors of wetting and non-equilibrium buffering. It is predicted that maximal weathering will continue until at least 20 percent of the total sulfide is consumed. Using the identified evolution of sulfide consumption in this Arctic climate, a variable rate factor can now be assessed for the possible early evolution and maximal weathering of larger scale waste-rock piles and seasonal differences because of changes in the volume of a waste-rock pile undergoing active weathering due to the freeze

  8. Active microwave measurements of sea ice under fall conditions: The RADARSAT/FIREX fall experiment. [in the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Onstott, R. G.; Kim, Y. S.; Moore, R. K.

    1984-01-01

    A series of measurements of the active microwave properties of sea ice under fall growing conditions was conducted. Ice in the inland waters of Mould Bay, Crozier Channel, and intrepid inlet and ice in the Arctic Ocean near Hardinge Bay was investigated. Active microwave data were acquired using a helicopter borne scatterometer. Results show that multiyear ice frozen in grey or first year ice is easily detected under cold fall conditions. Multiyear ice returns were dynamic due to response to two of its scene constituents. Floe boundaries between thick and thin ice are well defined. Multiyear pressure ridge returns are similar in level to background ice returns. Backscatter from homogeneous first year ice is seen to be primarily due to surface scattering. Operation at 9.6 GHz is more sensitive to the detailed changes in scene roughness, while operation at 5.6 GHz seems to track roughness changes less ably.

  9. Large herbivore grazing affects the vegetation structure and greenhouse gas balance in a high arctic mire

    NASA Astrophysics Data System (ADS)

    Falk, Julie Maria; Schmidt, Niels Martin; Christensen, Torben R.; Ström, Lena

    2015-04-01

    Herbivory is an important part of most ecosystems and affects the ecosystems’ carbon balance both directly and indirectly. Little is known about herbivory and its impact on the carbon balance in high arctic mire ecosystems. We hypothesized that trampling and grazing by large herbivores influences the vegetation density and composition and thereby also the carbon balance. In 2010, we established fenced exclosures in high arctic Greenland to prevent muskoxen (Ovibos moschatus) from grazing. During the growing seasons of 2011 to 2013 we measured CO2 and CH4 fluxes in these ungrazed blocks and compared them to blocks subjected to natural grazing. Additionally, we measured depth of the water table and active layer, soil temperature, and in 2011 and 2013 an inventory of the vegetation density and composition were made. In 2013 a significant decrease in total number of vascular plant (33-44%) and Eriophorum scheuchzeri (51-53%) tillers were found in ungrazed plots, the moss-layer and amount of litter had also increased substantially in these plots. This resulted in a significant decrease in net ecosystem uptake of CO2 (47%) and likewise a decrease in CH4 emission (44%) in ungrazed plots in 2013. While the future of the muskoxen in a changing arctic is unknown, this experiment points to a potentially large effect of large herbivores on the carbon balance in natural Arctic ecosystems. It thus sheds light on the importance of grazing mammals, and hence adds to our understanding of natural ecosystem greenhouse gas balance in the past and in the future.

  10. Application of well data in oil and gas assessment - Arctic National Wildlife Refuge

    USGS Publications Warehouse

    Nelson, Philip H.; Schenk, Christopher J.; Bird, Kenneth J.

    1998-01-01

    A current assessment of oil and gas resources in the Arctic National Wildlife Refuge 1002 area by the U.S. Geological Survey relies upon seismic data, geological mapping of exposures south and west of the assessment area and exploratory wells. Well data assembled for the 41 wells include: well logs, core descriptions and measurements, formation tops, biostratigraphic boundaries, drill-stem tests, casing points, fission-track age dates, vitrinite reflectance, and organic-carbon content. These data are used in the synthesis of all available data and presentation on a well-by-well basis, and extraction of volumetric parameters that are used to assess undiscovered accumulations.

  11. Arctic summary report: Outer Continental Shelf oil and gas activities in the Arctic and their onshore impacts

    NASA Astrophysics Data System (ADS)

    Lynch, C.; Slitor, D. L.; Rudolph, R. W.

    1985-01-01

    Issues and developments occuring in the Arctic Outer Continental Shelf subregion are discussed. The geology and hydrocarbon potential of the Diapir Field petroleum provinces are detailed. Recent lease sales, exploration activities, and the first development proposals for offshore areas of the North slope are considered. Issues relating to transporting resources from production islands to shore and various proposals for moving Arctic hydrocarbons to market are presented. Production projects onshore and possible support bases for offshore activity are also examined.

  12. Holocene sea ice history and climate variability along the main axis of the Northwest Passage, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Ledu, David; Rochon, André; de Vernal, Anne; Barletta, Francesco; St-Onge, Guillaume

    2010-06-01

    Palynological, geochemical, and physical records were used to document Holocene paleoceanographic changes in marine sediment core from Dease Strait in the western part of the main axis of the Northwest Passage (core 2005-804-006 PC latitude 68°59.552‧N, longitude 106°34.413‧W). Quantitative estimates of past sea surface conditions were inferred from the modern analog technique applied to dinoflagellate cyst assemblages. The chronology of core 2005-804-006 PC is based on a combined use of the paleomagnetic secular variation records and the CALS7K.2 time-varying spherical harmonic model of the geomagnetic field. The age-depth model indicates that the core spans the last ˜7700 cal years B.P., with a sedimentation rate of 61 cm ka-1. The reconstructed sea surface parameters were compared with those from Barrow Strait and Lancaster Sound (cores 2005-804-004 PC and 2004-804-009 PC, respectively), which allowed us to draw a millennial-scale Holocene sea ice history along the main axis of the Northwest Passage (MANWP). Overall, our data are in good agreement with previous studies based on bowhead whale remains. However, dinoflagellate sea surface based reconstructions suggest several new features. The presence of dinoflagellate cysts in the three cores for most of the Holocene indicates that the MANWP was partially ice-free over the last 10,000 years. This suggests that the recent warming observed in the MANWP could be part of the natural climate variability at the millennial time scale, whereas anthropogenic forcing could have accelerated the warming over the past decades. We associate Holocene climate variability in the MANWP with a large-scale atmospheric pattern, such as the Arctic Oscillation, which may have operated since the early Holocene. In addition to a large-scale pattern, more local conditions such as coastal current, tidal effects, or ice cap proximity may have played a role on the regional sea ice cover. These findings highlight the need to further

  13. Contrasting retinoid and thyroid hormone status in differentially-contaminated northern fulmar colonies from the Canadian Arctic, Svalbard and the Faroe Islands.

    PubMed

    Verreault, Jonathan; Helgason, Lisa B; Gabrielsen, Geir W; Dam, Maria; Braune, Birgit M

    2013-02-01

    The northern fulmar (Fulmarus glacialis) has previously been shown to accumulate a wide range, and occasionally high concentrations of organochlorines (OCs) (e.g., PCBs, chlorobenzenes, DDT- and chlordane-related compounds, dioxins and furans). The present study aimed to investigate, using a meta-analysis approach, the variations in cytochrome P450 (CYP) 1A-like enzyme induction based on ethoxyresorufin O-deethylase activity (EROD) and selected physiological variables (retinoids and thyroid hormones) in northern fulmar breeding in three differentially OC-exposed populations: Nunavut (Canadian Arctic), Svalbard (Norwegian Arctic) and the Faroe Islands. Substantially higher (roughly two-fold) OC levels were uncovered in the liver of this long-lived fulmarine petrel breeding in the Faroe Islands relative to Svalbard and Nunavut. Liver levels of PCDDs, PCDFs and non-ortho PCBs in Faroe Islands fulmars were amongst the highest reported thus far in any seabirds from the northern regions. Positive correlations were depicted in combined fulmars (all three populations) between hepatic EROD activity and concentrations of OCs, in which strongest associations were found for dioxin-like compound (PCDFs and PCDDs) and TEQ concentrations. Moreover, moderate to strong positive correlations were found between liver OC concentrations and plasma total thyroxin (TT(4)) levels and TT(4)/total triiodothyronine (TT(3)) level ratios, as well as strong negative correlations between the same suite of OCs and plasma TT(3) levels. Hepatic OC concentrations (PCBs, PCDDs, PCDFs, HCB, p,p'-DDE and oxychlordane) also were positively correlated with hepatic retinyl palmitate levels which, in turn, were associated with a significant decrease in plasma retinol levels and somewhat unchanged liver retinol levels. The present meta-analysis investigation on northern fulmar breeding in three geographically-distant sites illustrated that OC exposure (mainly PCBs and dioxins/furans) may be associated with

  14. Contrasting retinoid and thyroid hormone status in differentially-contaminated northern fulmar colonies from the Canadian Arctic, Svalbard and the Faroe Islands.

    PubMed

    Verreault, Jonathan; Helgason, Lisa B; Gabrielsen, Geir W; Dam, Maria; Braune, Birgit M

    2013-02-01

    The northern fulmar (Fulmarus glacialis) has previously been shown to accumulate a wide range, and occasionally high concentrations of organochlorines (OCs) (e.g., PCBs, chlorobenzenes, DDT- and chlordane-related compounds, dioxins and furans). The present study aimed to investigate, using a meta-analysis approach, the variations in cytochrome P450 (CYP) 1A-like enzyme induction based on ethoxyresorufin O-deethylase activity (EROD) and selected physiological variables (retinoids and thyroid hormones) in northern fulmar breeding in three differentially OC-exposed populations: Nunavut (Canadian Arctic), Svalbard (Norwegian Arctic) and the Faroe Islands. Substantially higher (roughly two-fold) OC levels were uncovered in the liver of this long-lived fulmarine petrel breeding in the Faroe Islands relative to Svalbard and Nunavut. Liver levels of PCDDs, PCDFs and non-ortho PCBs in Faroe Islands fulmars were amongst the highest reported thus far in any seabirds from the northern regions. Positive correlations were depicted in combined fulmars (all three populations) between hepatic EROD activity and concentrations of OCs, in which strongest associations were found for dioxin-like compound (PCDFs and PCDDs) and TEQ concentrations. Moreover, moderate to strong positive correlations were found between liver OC concentrations and plasma total thyroxin (TT(4)) levels and TT(4)/total triiodothyronine (TT(3)) level ratios, as well as strong negative correlations between the same suite of OCs and plasma TT(3) levels. Hepatic OC concentrations (PCBs, PCDDs, PCDFs, HCB, p,p'-DDE and oxychlordane) also were positively correlated with hepatic retinyl palmitate levels which, in turn, were associated with a significant decrease in plasma retinol levels and somewhat unchanged liver retinol levels. The present meta-analysis investigation on northern fulmar breeding in three geographically-distant sites illustrated that OC exposure (mainly PCBs and dioxins/furans) may be associated with

  15. Effect of Submarine Groundwater Discharge on Relict Arctic Submarine Permafrost and Gas Hydrate

    NASA Astrophysics Data System (ADS)

    Frederick, J. M.; Buffett, B. A.

    2014-12-01

    Permafrost-associated gas hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Degradation of this shallow water reservoir has the potential to release large quantities of methane gas directly to the atmosphere. Gas hydrate stability and the permeability of the shelf sediments to gas migration is closely linked with submarine permafrost. Submarine permafrost extent depends on several factors, such as the lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, and the salinity of the pore water. The salinity of the pore water is especially relevant because it partially controls the freezing point for both ice and gas hydrate. Measurements of deep pore water salinity are few and far between, but show that deep off-shore sediments are fresh. Deep freshening has been attributed to large-scale topographically-driven submarine groundwater discharge, which introduces fresh terrestrial groundwater into deep marine sediments. We investigate the role of submarine ground water discharge on the salinity field and its effects on the seaward extent of relict submarine permafrost and gas hydrate stability on the Arctic shelf with a 2D shelf-scale model based on the finite volume method. The model tracks the evolution of the temperature, salinity, and pressure fields given imposed boundary conditions, with latent heat of water ice and hydrate formation included. The permeability structure of the sediments is coupled to changes in permafrost. Results show that pore fluid is strongly influenced by the permeability variations imposed by the overlying permafrost layer. Groundwater discharge tends to travel horizontally off-shore beneath the permafrost layer and the freshwater-saltwater interface location displays long timescale transient behavior that is dependent on the groundwater discharge strength. The seaward permafrost extent is in turn strongly influenced by the

  16. Carbon fluxes in the Canadian Arctic: patterns and drivers of bacterial abundance, production and respiration on the Beaufort Sea margin

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Jeffrey, W. H.; Babin, M.; Bélanger, S.; Benner, R.; Marie, D.; Matsuoka, A.; Raimbault, P.; Joux, F.

    2012-05-01

    During August 2009, measurements of bacterial abundance and nucleic acid content were made along with production and respiration in coastal waters of the Beaufort Sea (Arctic Ocean), an area influenced by the Mackenzie River inflow. The main purpose was to evaluate bacterial organic carbon processing with respect to local sources, mainly primary production and river inputs. Bacterial production and abundance generally decreased from river to offshore waters and from surface to deep waters. In contrast, the percentage of high nucleic acid bacteria was higher in deep waters rather than in surface or river waters. Statistical analyses indicated that bacterial production was primarily controlled by temperature and the availability of labile organic matter, as indicated by total dissolved amino acid concentrations. Direct comparisons of bacterial carbon demand and primary production indicated net heterotrophy was common in shelf waters. Net autotrophy was observed at stations in the Mackenzie River plume, suggesting that the carbon fixed in plume waters helped fuel net heterotrophy in the Beaufort Sea margin.

  17. Carbon fluxes in the Canadian Arctic: patterns and drivers of bacterial abundance, production and respiration on the Beaufort Sea margin

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Jeffrey, W. H.; Babin, M.; Bélanger, S.; Benner, R.; Marie, D.; Matsuoka, A.; Raimbault, P.; Joux, F.

    2012-09-01

    During August 2009, measurements of bacterial abundance and nucleic acid content were made along with production and respiration in coastal waters of the Beaufort Sea (Arctic Ocean), an area influenced by the Mackenzie River inflow. The main purpose was to evaluate bacterial organic carbon processing with respect to local sources, mainly primary production and river inputs. Bacterial production and abundance generally decreased from river to offshore waters and from surface to deep waters. In contrast, the percentage of high nucleic acid bacteria was higher in deep waters rather than in surface or river waters. Statistical analyses indicated that bacterial production was primarily controlled by temperature and the availability of labile organic matter, as indicated by total dissolved amino acid concentrations. Direct comparisons of bacterial carbon demand and primary production indicated net heterotrophy was common in shelf waters. Net autotrophy was observed at stations in the Mackenzie River plume, suggesting that the carbon fixed in plume waters helped fuel net heterotrophy in the Beaufort Sea margin.

  18. Total mercury concentrations in anadromous Northern Dolly Varden from the northwestern Canadian Arctic: a historical baseline study.

    PubMed

    Tran, L; Reist, J D; Power, M

    2015-03-15

    Previous research has documented the significance of total mercury (THg) as a northern contaminant in general and of fish in particular. While much research has been devoted to documenting both spatial and temporal changes in THg in consumed fish, little effort has been directed at understanding patterns of THg in Dolly Varden (Salvelinus malma), a prized subsistence species throughout the western North American Arctic. Here we report historical THg concentrations for anadromous Dolly Varden from 10 populations in the Yukon and Northwest Territories sampled across a range of latitudes (67-69°N) and longitudes (136-141°W) between the years 1988-91. Unadjusted mean THg concentrations ranged from 15 to 254 ng/g wet weight. Length-adjusted THg concentrations were significantly different among sites, but were not related to latitude or longitude. Within and among populations, THg was significantly related to fork-length, age, δ(15)N, and δ(13)C, with the variation in THg found among populations being best explained by size. The data serve as an important baseline against which future changes in THg levels in this important subsistence fishery may be compared to determine the significance of any observed trends.

  19. Current-use pesticides in seawater and their bioaccumulation in polar bear-ringed seal food chains of the Canadian Arctic.

    PubMed

    Morris, Adam D; Muir, Derek C G; Solomon, Keith R; Letcher, Robert J; McKinney, Melissa A; Fisk, Aaron T; McMeans, Bailey C; Tomy, Gregg T; Teixeira, Camilla; Wang, Xiaowa; Duric, Mark

    2016-07-01

    The distribution of current-use pesticides (CUPs) in seawater and their trophodynamics were investigated in 3 Canadian Arctic marine food chains. The greatest ranges of dissolved-phase concentrations in seawater for each CUP were endosulfan sulfate (less than method detection limit (MDL) to 19 pg L(-1) ) > dacthal (0.76-15 pg L(-1) ) > chlorpyrifos (less than MDL to 8.1 pg L(-1) ) > pentachloronitrobenzene (less than MDL to 2.6 pg L(-1) ) > α-endosulfan (0.20-2.3 pg L(-1) ). Bioaccumulation factors (BAFs, water-respiring organisms) were greatest in plankton, including chlorothalonil (log BAF = 7.4 ± 7.1 L kg(-1) , mean ± standard error), chlorpyrifos (log BAF = 6.9 ± 6.7 L kg(-1) ), and α-endosulfan (log BAF = 6.5 ± 6.0 L kg(-1) ). The largest biomagnification factors (BMFs) were found for dacthal in the capelin:plankton trophic relationship (BMF = 13 ± 5.0) at Cumberland Sound (Nunvavut), and for β-endosulfan (BMF = 16 ± 4.9) and α-endosulfan (BMF = 9.3 ± 2.8) in the polar bear-ringed seal relationship at Barrow and Rae Strait (NU), respectively. Concentrations of endosulfan sulfate exhibited trophic magnification (increasing concentrations with increasing trophic level) in the poikilothermic portion of the food web (trophic magnification factor = 1.4), but all of the CUPs underwent trophic dilution in the marine mammal food web, despite some trophic level-specific biomagnification. Together, these observations are most likely indicative of metabolism of these CUPs in mammals. Environ Toxicol Chem 2016;35:1695-1707. © 2016 SETAC. PMID:27027986

  20. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J. F.

    2013-04-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean, with a particular focus on free-living (FL) vs. particle-attached (PA) communities. Capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Pyrosequencing of 16S rRNA genes from selected samples confirmed significant differences between river, coastal and sea samples. The PA fraction was only different (15.7% similarity) from the FL one in the open sea sample. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, for the coast and river samples and both PA and FL fractions, Betaproteobacteria, Alphaproteobacteria and Actinobacteria were dominant. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also

  1. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J.-F.

    2012-12-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea, Canadian Arctic Ocean, with a particular focus on free-living vs. particle-attached communities. Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between particle-attached (PA) and free-living (FL) bacterial communities in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (proxy of DOC and CDOM), suspended particles, amino acids and chlorophyll a. 16S rRNA genes pyrosequencing of selected samples confirmed these significant differences from river to sea and also between PA and FL fractions only in open sea samples, and PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, the coast and river samples, both PA and FL fractions, were dominated by Betaproteobacteria, Alphaproteobacteria and Actinobacteria. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a~basis to predict further changes in bacterial communities should climate change lead to further

  2. Heterotrophic microbial colonization of the interior of impact-shocked rocks from Haughton impact structure, Devon Island, Nunavut, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Fike, David A.; Cockell, Charles; Pearce, David; Lee, Pascal

    2002-10-01

    The polar desert is one of the most extreme environments on Earth. Endolithic organisms can escape or mitigate the hazards of the polar desert by using the resources available in the interior of rocks. We examined endolithic communities within crystalline rocks that have undergone shock metamorphism as a result of an asteroid or comet impact. Specifically, we present a characterization of the heterotrophic endolithic community and its environment in the interior of impact-shocked gneisses and their host polymict breccia from the Haughton impact structure on Devon Island, Nunavut, Canadian High Arctic. Microbiological colonization of impact-shocked rocks is facilitated by impact-induced fissures and cavities, which occur throughout the samples, the walls of which are lined with high abundances of biologically important elements owing to the partial volatilization of minerals within the rock during the impact. 27 heterotrophic bacteria were isolated from these shocked rocks and were identified by 16S rDNA sequencing. The isolates from the shocked gneiss and the host breccia are similar to each other, and to other heterotrophic communities isolated from polar environments, suggesting that the interiors of the rocks are colonized by microorganisms from the surrounding country rocks and soils. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to identify the chemical composition of the shocked materials and to document the in situ growth of microbes in their interiors. The identification of these heterotrophic communities within impact-shocked crystalline rocks extends our knowledge of the habitable biosphere on Earth. The colonization of the interiors of these samples has astrobiological applications both for considering terrestrial, microbiological contamination of meteorites from the Antarctic ice sheet and for investigating possible habitats for microbial

  3. Current-use pesticides in seawater and their bioaccumulation in polar bear-ringed seal food chains of the Canadian Arctic.

    PubMed

    Morris, Adam D; Muir, Derek C G; Solomon, Keith R; Letcher, Robert J; McKinney, Melissa A; Fisk, Aaron T; McMeans, Bailey C; Tomy, Gregg T; Teixeira, Camilla; Wang, Xiaowa; Duric, Mark

    2016-07-01

    The distribution of current-use pesticides (CUPs) in seawater and their trophodynamics were investigated in 3 Canadian Arctic marine food chains. The greatest ranges of dissolved-phase concentrations in seawater for each CUP were endosulfan sulfate (less than method detection limit (MDL) to 19 pg L(-1) ) > dacthal (0.76-15 pg L(-1) ) > chlorpyrifos (less than MDL to 8.1 pg L(-1) ) > pentachloronitrobenzene (less than MDL to 2.6 pg L(-1) ) > α-endosulfan (0.20-2.3 pg L(-1) ). Bioaccumulation factors (BAFs, water-respiring organisms) were greatest in plankton, including chlorothalonil (log BAF = 7.4 ± 7.1 L kg(-1) , mean ± standard error), chlorpyrifos (log BAF = 6.9 ± 6.7 L kg(-1) ), and α-endosulfan (log BAF = 6.5 ± 6.0 L kg(-1) ). The largest biomagnification factors (BMFs) were found for dacthal in the capelin:plankton trophic relationship (BMF = 13 ± 5.0) at Cumberland Sound (Nunvavut), and for β-endosulfan (BMF = 16 ± 4.9) and α-endosulfan (BMF = 9.3 ± 2.8) in the polar bear-ringed seal relationship at Barrow and Rae Strait (NU), respectively. Concentrations of endosulfan sulfate exhibited trophic magnification (increasing concentrations with increasing trophic level) in the poikilothermic portion of the food web (trophic magnification factor = 1.4), but all of the CUPs underwent trophic dilution in the marine mammal food web, despite some trophic level-specific biomagnification. Together, these observations are most likely indicative of metabolism of these CUPs in mammals. Environ Toxicol Chem 2016;35:1695-1707. © 2016 SETAC.

  4. Persistent organic pollutants and metals in the freshwater biota of the Canadian Subarctic and Arctic: an overview.

    PubMed

    Evans, Marlene S; Muir, Derek; Lockhart, W Lyle; Stern, Gary; Ryan, M; Roach, Pat

    2005-12-01

    Over 1999-2002, an extensive series of contaminant studies was conducted on freshwater biota of Canada's Arctic and Subarctic regions. The majority of inorganic contaminant studies focused on mercury and fish. While mercury concentrations were low in benthic feeding fish such as whitefish, predatory fish such as lake trout, pike, and walleye frequently had mercury levels which exceeded 0.2 mug/g, the consumption guideline for frequent consumers of fish, and 0.5 microg/g, the guideline for the commercial use of fish. Numerous consumption advisories were issued for lakes along the Mackenzie River. Relatively high mercury levels appear to be due to a combination of relatively old fish populations (because of light fishing pressures) and tend to be more prevalent in smaller lakes where warmer summer water temperatures and watershed influences result in greater mercury and methyl mercury inputs. Mercury levels were substantially lower in char than in lake trout, possibly due to a combination of a less fish-rich diet, a colder environment, and smaller MeHg watershed inputs. Less research has been conducted on other metals but some, such as rubidium, show pronounced variations in concentration that may be related to geological influences. Temporal trend monitoring has revealed little evidence of declining mercury levels in fish that can be attributed to declining atmospheric inputs. Because mercury follows complex pathways in the environment, other factors may operate to counteract reductions in atmospheric mercury sources, e.g., climatic variability, changes in the commercial fishery, and interactions between fish species. Most organochlorine (OC) investigations were based on long term trend monitoring and focused on char (Cornwallis Island), burbot (Great Slave Lake, Yukon lakes, Slave River at Fort Smith, Mackenzie River at Fort Good Hope) and lake trout (Yukon lakes, Great Slave Lake). There was strong evidence of declining OC concentrations in char, particularly

  5. Vitamin A and E profiles as biomarkers of PCB exposure in beluga whales (Delphinapterus leucas) from the western Canadian Arctic.

    PubMed

    Desforges, Jean-Pierre W; Ross, Peter S; Dangerfield, Neil; Palace, Vince P; Whiticar, Michael; Loseto, Lisa L

    2013-10-15

    We evaluated the utility of vitamin A and E profiles as biomarkers of contaminant exposure in beluga whales (Delphinapterus leucas; n=66) harvested by the Inuvialuit in the Beaufort Sea. Blubber was an important repository for these vitamins, accounting for 76.8±2.6% of the total body store of vitamin A, and 98.5±0.4% of total vitamin E. While the free alcohol form of vitamin A (retinol) appeared highly regulated, the vitamin A esters were influenced by several biological factors including age, body condition and length. Vitamin E concentrations in liver and blubber were related to age, condition, length and feeding ecology, as described δ(15)N and δ(13)C. Despite the influence of these factors, collective results from univariate statistics, best fit multiple regressions, and principal component analysis (PCA) identified polychlorinated biphenyls (PCBs) as important determinants of vitamin concentrations and profiles in beluga tissues. Blubber PCB concentrations best explained variation of the first principal component in a PCA of hepatic vitamins (r(2)=0.13, p=0.014), and regression models found that vitamin A concentrations were negatively correlated with PCB levels in liver (esters: r(2)=0.19, p=0.001), but positively in plasma (retinol: r(2)=0.20, p=0.06) and blubber (retinol: r(2)=0.22, p=0.001, esters: r(2)=0.43, p<0.001). Our analyses provide a basis to propose an integrated toxicity reference value for disruption of vitamin A and E profiles in beluga of 1.6 mg/kg lw PCBs. This disruption of vitamin profiles by moderate levels of PCBs in an arctic cetacean highlights the global reach and impact of these legacy chemicals decades after their peak use.

  6. Water systems, sanitation, and public health risks in remote communities: Inuit resident perspectives from the Canadian Arctic.

    PubMed

    Daley, Kiley; Castleden, Heather; Jamieson, Rob; Furgal, Chris; Ell, Lorna

    2015-06-01

    Safe drinking water and wastewater sanitation are universally recognized as critical components of public health. It is well documented that a lack of access to these basic services results in millions of preventable deaths each year among vulnerable populations. Water and wastewater technologies and management practices are frequently tailored to local environmental conditions. Also important, but often overlooked in water management planning, are the social, cultural and economic contexts in which services are provided. The purpose of this qualitative case study was to identify and understand residents' perceptions of the functionality of current water and wastewater sanitation systems in one vulnerable context, that of a remote Arctic Aboriginal community (Coral Harbour, Nunavut), and to identify potential future water related health risks. Semi-structured interviews were conducted with 28 Inuit residents and 9 key informants in 2011 and 2012. Findings indicate that the population's rapid transition from a semi-nomadic hunting and gathering lifestyle to permanent settlements with municipally provided utilities is influencing present-day water usage patterns, public health perceptions, and the level of priority decision-makers place on water and wastewater management issues. Simultaneously environmental, social and cultural conditions conducive to increased human exposure to waterborne health risks were also found to exist and may be increasing in the settlements. While water and wastewater system design decisions are often based on best practices proven suitable in similar environmental conditions, this study reinforces the argument for inclusion of social, cultural, and economic variables in such decisions, particularly in remote and economically challenged contexts in Canada or elsewhere around the world. The results also indicate that the addition of qualitative data about water and wastewater systems users' behaviours to technical knowledge of systems and

  7. Vitamin A and E profiles as biomarkers of PCB exposure in beluga whales (Delphinapterus leucas) from the western Canadian Arctic.

    PubMed

    Desforges, Jean-Pierre W; Ross, Peter S; Dangerfield, Neil; Palace, Vince P; Whiticar, Michael; Loseto, Lisa L

    2013-10-15

    We evaluated the utility of vitamin A and E profiles as biomarkers of contaminant exposure in beluga whales (Delphinapterus leucas; n=66) harvested by the Inuvialuit in the Beaufort Sea. Blubber was an important repository for these vitamins, accounting for 76.8±2.6% of the total body store of vitamin A, and 98.5±0.4% of total vitamin E. While the free alcohol form of vitamin A (retinol) appeared highly regulated, the vitamin A esters were influenced by several biological factors including age, body condition and length. Vitamin E concentrations in liver and blubber were related to age, condition, length and feeding ecology, as described δ(15)N and δ(13)C. Despite the influence of these factors, collective results from univariate statistics, best fit multiple regressions, and principal component analysis (PCA) identified polychlorinated biphenyls (PCBs) as important determinants of vitamin concentrations and profiles in beluga tissues. Blubber PCB concentrations best explained variation of the first principal component in a PCA of hepatic vitamins (r(2)=0.13, p=0.014), and regression models found that vitamin A concentrations were negatively correlated with PCB levels in liver (esters: r(2)=0.19, p=0.001), but positively in plasma (retinol: r(2)=0.20, p=0.06) and blubber (retinol: r(2)=0.22, p=0.001, esters: r(2)=0.43, p<0.001). Our analyses provide a basis to propose an integrated toxicity reference value for disruption of vitamin A and E profiles in beluga of 1.6 mg/kg lw PCBs. This disruption of vitamin profiles by moderate levels of PCBs in an arctic cetacean highlights the global reach and impact of these legacy chemicals decades after their peak use. PMID:24077185

  8. Water systems, sanitation, and public health risks in remote communities: Inuit resident perspectives from the Canadian Arctic.

    PubMed

    Daley, Kiley; Castleden, Heather; Jamieson, Rob; Furgal, Chris; Ell, Lorna

    2015-06-01

    Safe drinking water and wastewater sanitation are universally recognized as critical components of public health. It is well documented that a lack of access to these basic services results in millions of preventable deaths each year among vulnerable populations. Water and wastewater technologies and management practices are frequently tailored to local environmental conditions. Also important, but often overlooked in water management planning, are the social, cultural and economic contexts in which services are provided. The purpose of this qualitative case study was to identify and understand residents' perceptions of the functionality of current water and wastewater sanitation systems in one vulnerable context, that of a remote Arctic Aboriginal community (Coral Harbour, Nunavut), and to identify potential future water related health risks. Semi-structured interviews were conducted with 28 Inuit residents and 9 key informants in 2011 and 2012. Findings indicate that the population's rapid transition from a semi-nomadic hunting and gathering lifestyle to permanent settlements with municipally provided utilities is influencing present-day water usage patterns, public health perceptions, and the level of priority decision-makers place on water and wastewater management issues. Simultaneously environmental, social and cultural conditions conducive to increased human exposure to waterborne health risks were also found to exist and may be increasing in the settlements. While water and wastewater system design decisions are often based on best practices proven suitable in similar environmental conditions, this study reinforces the argument for inclusion of social, cultural, and economic variables in such decisions, particularly in remote and economically challenged contexts in Canada or elsewhere around the world. The results also indicate that the addition of qualitative data about water and wastewater systems users' behaviours to technical knowledge of systems and

  9. A ground-based trace gas observing system for detection of Arctic and Boreal change

    NASA Astrophysics Data System (ADS)

    Karion, A.; Miller, J. B.; Sweeney, C.; Bruhwiler, L.; Newberger, T.; Miller, C. E.; Dinardo, S. J.; Wolter, S.; Ledlow, L.

    2012-12-01

    The large reservoir of below-ground organic carbon in the Arctic and Boreal region (ABR) permafrost, combined with large observed and predicted temperature changes leads to the expectation of increasing surface emissions of CO2 and/or CH4 this century. However, the near-term response of northern ecosystems could be enhanced ecosystem productivity and carbon sequestration via, among other causes, longer growing seasons and encroachment of woody species into Arctic tundra. Regardless of the temporal evolution of carbon (both CO2 and CH4) sources and sinks in the ABR, monitoring these changes at regional (~10^5 - 10^6 km^2) scales using trace gas mixing and isotopic ratios will be a critical complement to detailed process-based studies at the plot scale and remote sensing of the land surface. Turbulent mixing in the lower few kilometers of the atmosphere naturally integrates emissions from all known and unknown processes and can provide a powerful bottom-line constraint on the net result of both sources and sinks. We will present the first year of results of a trace-gas measurement system capable of daily or more frequent observations of more than 50 trace gas species, including CO2, CH4 and their stable and radio isotope ratios. The measurements were initiated as part of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and come from a 30 m tower located on a ridge in central Alaska. Central Alaska is dominated by discontinuous permafrost, which is likely to undergo significant changes in the coming decades. Footprint analysis suggests that mixing ratios measured at the tower are influenced by large swaths of central Alaska, although in winter, anthropogenic emissions form the city of Fairbanks are evident. In summer, as expected, we observe a large drawdown of CO2. The seasonal cycle of CH4 is dominated by the large-scale destruction of methane by hydroxyl radical (OH). However, based on previous measurements from other ABR sites, we expect summer

  10. Prevalence of zoonotic anisakid nematodes in Inuit-harvested fish and mammals from the eastern Canadian Arctic.

    PubMed

    Pufall, Erica L; Jones-Bitton, Andria; McEwen, Scott A; Brown, Tanya M; Edge, Victoria L; Rokicki, Jerzy; Karpiej, Katarzyna; Peregrine, Andrew S; Simard, Manon

    2012-11-01

    Human anisakidosis is a recognized Arctic zoonosis that is directly related to the consumption of traditional Inuit foods, particularly raw fish. The epidemiology of infections with the zoonotic anisakid nematodes Anisakis simplex and Pseudoterranova decipiens was investigated from August 2007 to July 2009 in Inuit-harvested fish and marine mammals from Inuit regions of Nunavik, Nunavut, and Nunatsiavut, Canada. Fish were tested for anisakid larvae using the pepsin-HCl digestion method, and the stomachs or stomach contents of beluga whales, walruses, and three seal species were examined for anisakids. Anisakids were found in seven of eight fish species, as well as in ringed seals (18.2%; 31/170), bearded seals (75.0%; 12/16), and beluga whales (78.9%; 15/19), but not walruses (0%; 0/15). In fish, the odds of being infected with A. simplex and/or P. decipiens was 68.6 (95% confidence interval, 11.6-627.7) times higher in marine fish than in anadromous fish, after adjusting for length of fish. Negative binomial models were created for animal species with large enough sample sizes and parasite prevalence estimates to assess risk factors associated with anisakid abundance. In seals, the only risk factor significantly associated with increasing anisakid abundance was increasing length (p < 0.01), while in beluga whales, the only significant risk factor was year of capture (p = 0.03). In fish, length was the variable most commonly associated with increased anisakid larval abundance, with longer fish having significantly higher larval abundances than shorter fish of the same species. The presence of A. simplex and P. decipiens in bearded seals, ringed seals, and beluga whales from Inuit hunting grounds suggests that they likely act as definitive hosts for these parasites in these environments. With respect to zoonotic disease risk associated with Inuit country foods, among the species of fish examined, Atlantic tomcod, polar cod, and sculpins represented the greatest risk

  11. Contribution of oceanic gas hydrate dissociation to the formation of Arctic Ocean methane plumes

    SciTech Connect

    Reagan, M.; Moridis, G.; Elliott, S.; Maltrud, M.

    2011-06-01

    Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of carbon into the atmosphere. Because methane is a powerful greenhouse gas, such a release could have dramatic climatic consequences. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope (150 m - 400 m) west of Svalbard suggests that this process may already have begun, but the source of the methane has not yet been determined. This study performs 2-D simulations of hydrate dissociation in conditions representative of the Arctic Ocean margin to assess whether such hydrates could contribute to the observed gas release. The results show that shallow, low-saturation hydrate deposits, if subjected to recently observed or future predicted temperature changes at the seafloor, can release quantities of methane at the magnitudes similar to what has been observed, and that the releases will be localized near the landward limit of the GHSZ. Both gradual and rapid warming is simulated, along with a parametric sensitivity analysis, and localized gas release is observed for most of the cases. These results resemble the recently published observations and strongly suggest that hydrate dissociation and methane release as a result of climate change may be a real phenomenon, that it could occur on decadal timescales, and that it already may be occurring.

  12. 77 FR 2513 - Draft Environmental Impact Statement for Effects of Oil and Gas Activities in the Arctic Ocean

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-18

    ... the Notice of Availability (76 FR 82275, December 30, 2011). Public Meetings Comments will be accepted... in the Notice of Availability Federal Register document (76 FR 82275, December 30, 2011)) will be... Effects of Oil and Gas Activities in the Arctic Ocean AGENCY: National Marine Fisheries Service...

  13. Gas flux dynamics in high arctic permafrost polygon and ice wedge active layer soil; microbial feedback implications

    NASA Astrophysics Data System (ADS)

    Mykytczuk, N. C.; Stackhouse, B. T.; Bennett, P.; Lamarche-Gagnon, G.; Hettich, R. L.; Phelps, T. J.; Layton, A.; Pfiffner, S. M.; Allan, J.; Vishnivetskaya, T. A.; Chourey, K.; Whyte, L.; Onstott, T. C.

    2011-12-01

    Temperatures in the Arctic may increase 4-8°C over the next 100 years, thereby increasing the depth of the active layer (AL) and thawing the underlying permafrost, with ice wedges in particular acting as an early indicator, a bellwether, for changing permafrost. Although data on CO2 and CH4 fluxes have been studied along with microbial diversity of AL and permafrost environments, the relationship between methanogenic, methanotrophic and heterotrophic in situ activities within the AL and CO2 and CH4 fluxes as a function of temperature has not been delineated. Defining these relationships is critical for accurately modeling the extent and rate of + / - feedback in global climate models. Initial field investigations of diurnal CO2 and CH4 flux from permafrost and ice-wedge AL soils were conducted during July on Axel Heiberg Island in the Canadian high arctic. The AL soils (68-69 cm depth) were completely thawed while ambient air temperatures were between 9 and 27°C. The AL soils above the ice wedges had a higher water content and finer texture than the polygon AL soils. Diurnal patterns using in situ flux chambers and a Picarro C-13 CO2 cavity ring-down spectrometer recorded net outward flux of CO2 (3.2 to 8.8 g/m2/day) and consumption of atmospheric CH4 (-2.2 mg/m2/day) from the AL surfaces. Gas flux from the ice wedge soil surface were in a similar range as the polygon soil surface, having slightly higher maximal flux of CO2 (10.4 g/m2/day) and net efflux of CH4 (-2.2 to 14 mg/m2/day). Using a vertical probe, gas flux below the surface measured higher amounts of CO2 with increasing depth ranging from 10.4 to 21.4 g/m2/day in the polygon soils vs. 10 to 28.5 g/m2/day in the ice wedge soils. Through the same profile, the CH4 concentration decreased from 0.59 ppmv to < 0.1 ppmv within 30 cm of the surface in the ice wedge and from 1.1 to 0.54 ppmv at the base of the polygon AL. The δ13C of the CO2 efflux from the surface were consistent with microbial activity

  14. Evidence for bacterially generated hydrocarbon gas in Canadian shield and Fennoscandian shield rocks

    SciTech Connect

    Lollar, B.S.; Frape, S.K. ); Fritz, P. ); Macko, S.A. ); Welhan, J.A. ); Blomqvist, R.; Lahermo, P.W. )

    1993-12-01

    Hydrocarbon-rich gases found in crystalline rocks on the Canadian and Fennoscandian shields are isotopically and compositionally similar, suggesting that such gases are a characteristic feature of Precambrian Shields rocks. Gases occur in association with saline groundwaters and brines in pressurized [open quotes]pockets[close quotes] formed by sealed fracture systems within the host rocks. When released by drilling activities, gas pressures as high as 5000 kPa have been recorded. Typical gas flow rates for individual boreholes range from 0.25 L/min to 4 L/min. The highest concentrations of CH[sub 4] are found in the deepest levels of the boreholes associated with Ca-Na-Cl (and Na-Ca-Cl) brines. N[sub 2] is the second major component of the gases and with CH[sub 4] accounts for up to 80 to >90 vol%. Higher hydrocarbon (C[sup +][sub 2]) concentrations range from <1 to 10 vol%, with Cl/(C2 + C3) ratios from 10-1000. Isotopically the gases show a wide range of values overall ([delta][sup 13]C = -57.5 to -41.1%; [delta]D = -245 to -470%) but a relatively tight cluster of values within each sampling locality. The Enonkoski Mine methanes are unique with [delta][sup 13]C values between -65.4 and -67.3% and [delta]D values between -297 and -347%. The shield gases are not readily reconcilable with conventional theories of methanogenesis. The range of C1/(C2 + C3) ratios for the shield gases is too low to be consistent with an entirely bacterial origin. In addition, [delta]D[sub CH4] values are in general too depleted in the heavy isotope to be produced by thermogenic methanogenesis or by secondary alteration processes such as bacterial oxidation or migration. However, isotopic and compositional evidence indicates that bacterially derived gas can account for a significant component of the gas at all shield sites.

  15. Environmental influences of oil and gas development in the Arctic Slope and Beaufort Sea

    USGS Publications Warehouse

    Brooks, J.W.; Bartonek, J.C.; Klein, D.R.; Spencer, D.

    1971-01-01

    This report describes the environmental characteristics and renewable resources of the Arctic Slope and the Beaufort Sea in relation to oil and gas development. Problems associated with industrial activities are identified, and recommendations for avoiding or minimizing environmental and resource damage are advanced. It is noted that the simplicity of the ecosystems, the slow rate of organic processes, and the presence of permafrost create unique problems in connection with pollution, waste disposal, restoration of vegetation, and all activities which disturb the vegetated surface. In the Beaufort Sea, the shallowness of the continental shelf and the presence of pack ice represent serious physical obstacles to oil development and transportation and heighten the probability of potentially harmful accidents. The risk of serious environmental and resource damage in the Arctic will be greatly lessened by the imposition of high operational and safety standards. There is need for strengthening legal authority to promulgate essential regulations. As an interim substitute, close and effective cooperation between Government and industry must be developed. Both Government and industry have an obligation to support research aimed at providing an adequate understanding of numerous environmental and technical questions.

  16. Velocity models and images using full waveform inversion and reverse time migration for the offshore permafrost in the Canadian shelf of Beaufort Sea, Arctic

    NASA Astrophysics Data System (ADS)

    Kang, S. G.; Hong, J. K.; Jin, Y. K.; Kim, S.; Kim, Y. G.; Dallimore, S.; Riedel, M.; Shin, C.

    2015-12-01

    During Expedition ARA05C (from Aug 26 to Sep 19, 2014) on the Korean icebreaker RV ARAON, the multi-channel seismic (MCS) data were acquired on the outer shelf and slope of the Canadian Beaufort Sea to investigate distribution and internal geological structures of the offshore ice-bonded permafrost and gas hydrates, totaling 998 km L-km with 19,962 shots. The MCS data were recorded using a 1500 m long solid-type streamer with 120 channels. Shot and group spacing were 50 m and 12.5 m, respectively. Most MCS survey lines were designed perpendicular and parallel to the strike of the shelf break. Ice-bonded permafrost or ice-bearing sediments are widely distributed under the Beaufort Sea shelf, which have formed during periods of lower sea level when portions of the shelf less than ~100m water depth were an emergent coastal plain exposed to very cold surface. The seismic P-wave velocity is an important geophysical parameter for identifying the distribution of ice-bonded permafrost with high velocity in this area. Recently, full waveform inversion (FWI) and reverse time migration (RTM) are commonly used to delineate detailed seismic velocity information and seismic image of geological structures. FWI is a data fitting procedure based on wave field modeling and numerical analysis to extract quantitative geophysical parameters such as P-, S-wave velocities and density from seismic data. RTM based on 2-way wave equation is a useful technique to construct accurate seismic image with amplitude preserving of field data. In this study, we suggest two-dimensional P-wave velocity model (Figure.1) using the FWI algorithm to delineate the top and bottom boundaries of ice-bonded permafrost in the Canadian shelf of Beaufort Sea. In addition, we construct amplitude preserving migrated seismic image using RTM to interpret the geological history involved with the evolution of permafrost.

  17. On the gas hydtrate methane emissions and possible hypoxia in the East Siberian Arctic Seas

    NASA Astrophysics Data System (ADS)

    Iakovlev, Nikolay

    2014-05-01

    Recent field companies showed the high concentrations of dissolved methane in the region of East Siberian Arctic Seas (ESAS). These high concentrations were attributed to the degradation of the underwater permafrost which corked the methane from the shallow gas-hydrates deposits (Shakhova, et. al., 2010). Some aspects of the problem of the methane evolution, released at ESAS, were investigated in (Malakhova amd Golubeva, 2013), where the estimated methane emission to the atmosphere was two order lower than the estimates by Shakhova, et.al., 2010. In this study the version of the regional 3D coupled ice-ocean model FEMAO-1 was applied to the problem of the methane transport, oxidation and emission to the atmosphere. Model was driven by the AOMIP-FAMOS forcing 1948-2011, and showed the steady rise of mean bottom temperature at ESAS after 1990 till now. This temperature rise assumed to be sufficient to destabilize undersea permafrost and provoke the additional methane release from gas-hydrates. A set of numerical experiments were carried out to simulate various scenarios of the methane evolution: 1. The quasi-equilibrium state of the dissolved methane distribution forced by the sources at the continental slope and river runoff transport for the period of 1948-1990. This set of experiments was aimed to reproduce the observed methane concentrations and to tune the model parameterizations. 2. The scenario of ESAS abrupt methane release during 1990-2011 with various fractions of dissolved methane and bubbles. The fractions of the dissolved methane and bubbles were previously estimated in (Stepanenko and Iakovlev, 2013). This set of experiments was aimed to reproduce the observed vertical methane distribution with maximum at the ocean surface. 3. The ESAS abrupt methane release with limitation of oxidation in areas of hypoxia. This set of experiments was aimed to evaluate the possibility of hypoxia at the ESAS shelf and beyond, and to estimate the required methane flux to

  18. Arctic Gas Phase Water Vapor Measurements from the NASA DC-8 During SOLVE

    NASA Technical Reports Server (NTRS)

    Podolske, James; Sachse, Glen; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The NASA Langley / Ames Diode Laser Hygrometer (DLH) was flown aboard the NASA DC-8 during all three arctic deployments of the SOLVE campaign. The DLH measures gas phase H2O in the freestream air between the fuselage and the outer right engine cowling, essentially free from aircraft perturbations. It uses wavelength-modulated near-IR laser radiation at about 1.4 microns to detect the H2O absorption. Calibration is based on short path experiments in the laboratory using a NIST-traceable dewpoint hygrometer with carefully conditioned air at dewpoints between - 10 and + 10 degrees C. The theory of operation of the DLH instrument will be presented, along with a description of the calibration methodology. A simple climatology of H2O observations from SOLVE will be presented.

  19. Impact origin of the Avak Structure, Arctic Alaska, and genesis of the Barrow gas fields

    USGS Publications Warehouse

    Kirschner, C.E.; Grantz, A.; Mullen, M.W.

    1992-01-01

    Geophysical and subsurface geologic data suggest that the Avak structure, which underlies the Arctic Coastal Plain 12 km southeast of Barrow, Alaska, is a hypervelocity meteorite or comet impact structure. The structure is a roughly circular area of uplifted, chaotically deformed Upper Triassic to Lower Cretaceous sedimentary rocks 8 km in diameter that is bounded by a ring of anastomosing, inwardly dipping, listric normal faults 12 km in diameter. Examination of cores from the Barrow gas fields and data concerning the age of the Avak structure suggest that the Avak meteorite struck a Late Cretaceous or Tertiary marine shelf or coastal plain between the Cenomanian (ca. 95 Ma), and deposition of the basal beds of the overlying late Pliocene and Quaternary Gubik Formation (ca. 3 Ma). -from Authors

  20. Rapid Arctic Changes due to Infrastructure and Climate (RATIC) in the Russian North

    NASA Astrophysics Data System (ADS)

    Walker, D. A.; Kofinas, G.; Raynolds, M. K.; Kanevskiy, M. Z.; Shur, Y.; Ambrosius, K.; Matyshak, G. V.; Romanovsky, V. E.; Kumpula, T.; Forbes, B. C.; Khukmotov, A.; Leibman, M. O.; Khitun, O.; Lemay, M.; Allard, M.; Lamoureux, S. F.; Bell, T.; Forbes, D. L.; Vincent, W. F.; Kuznetsova, E.; Streletskiy, D. A.; Shiklomanov, N. I.; Fondahl, G.; Petrov, A.; Roy, L. P.; Schweitzer, P.; Buchhorn, M.

    2015-12-01

    The Rapid Arctic Transitions due to Infrastructure and Climate (RATIC) initiative is a forum developed by the International Arctic Science Committee (IASC) Terrestrial, Cryosphere, and Social & Human working groups for developing and sharing new ideas and methods to facilitate the best practices for assessing, responding to, and adaptively managing the cumulative effects of Arctic infrastructure and climate change. An IASC white paper summarizes the activities of two RATIC workshops at the Arctic Change 2014 Conference in Ottawa, Canada and the 2015 Third International Conference on Arctic Research Planning (ICARP III) meeting in Toyama, Japan (Walker & Pierce, ed. 2015). Here we present an overview of the recommendations from several key papers and posters presented at these conferences with a focus on oil and gas infrastructure in the Russian north and comparison with oil development infrastructure in Alaska. These analyses include: (1) the effects of gas- and oilfield activities on the landscapes and the Nenets indigenous reindeer herders of the Yamal Peninsula, Russia; (2) a study of urban infrastructure in the vicinity of Norilsk, Russia, (3) an analysis of the effects of pipeline-related soil warming on trace-gas fluxes in the vicinity of Nadym, Russia, (4) two Canadian initiatives that address multiple aspects of Arctic infrastructure called Arctic Development and Adaptation to Permafrost in Transition (ADAPT) and the ArcticNet Integrated Regional Impact Studies (IRIS), and (5) the effects of oilfield infrastructure on landscapes and permafrost in the Prudhoe Bay region, Alaska.

  1. A subglacial landform assemblage on the outer-shelf of M'Clure Strait, Canadian Arctic, ploughed by deglacial iceberg keels

    NASA Astrophysics Data System (ADS)

    Batchelor, Christine; Dowdeswell, Julian; Dowdeswell, Evelyn; Todd, Brian

    2015-04-01

    M'Clure Strait in the Canadian Beaufort Sea is one of the largest cross-shelf troughs in the High Arctic, with a length of over 1000 km and a maximum cross-trough width of around 250 km. M'Clure Strait has been suggested to be the former location of a fast-flowing ice stream which drained the northwestern margin of the Laurentide Ice Sheet during the Late Wisconsinan glaciation, and probably also during a number of earlier Quaternary full-glacial periods. The Late Wisconsinan ice stream in M'Clure Strait is interpreted to have extended to the shelf break between 21 and 16 ka ago, before undergoing rapid retreat. The ice stream has been suggested to have undergone vigorous episodes of activity during the last deglaciation; ice export events from the M'Clure Strait ice stream may have been responsible for the formation of distinctive layers of ice-rafted debris in the Arctic Ocean during regional deglaciation. Here, we present multibeam bathymetric data of the seafloor of outermost M'Clure Strait. Low rates of post-glacial sedimentation have led to the preservation of an unusual assemblage of cross-cutting subglacial, glacifluvial and glacimarine landforms on the M'Clure Strait seafloor. The assemblage of glacigenic landforms records the advance and retreat of a fast-flowing ice stream. Highly-elongate mega-scale glacial lineations (MSGLs) provide evidence for the advance of the last, Late Wisconsinan ice stream through M'Clure Strait to within at least 8 km of the shelf break. The preservation of the MSGLs and the lack of ice-flow transverse landforms indicate rapid ice retreat from this region of the outer-shelf. Trough-parallel sinuous esker-like ridges of sediment are also identified. These were probably formed by the sedimentary infilling of ice-walled subglacial meltwater conduits during deglaciation. This interpretation requires considerable volumes of meltwater and sediment to have been transported within subglacial channels beneath the M'Clure Strait ice

  2. Methane cross-validation between three Fourier Transform Spectrometers: SCISAT ACE-FTS, GOSAT TANSO-FTS, and ground-based FTS measurements in the Canadian high Arctic

    NASA Astrophysics Data System (ADS)

    Holl, G.; Walker, K. A.; Conway, S.; Saitoh, N.; Boone, C. D.; Strong, K.; Drummond, J. R.

    2015-12-01

    We present cross-validation of remote sensing measurements of methane profiles in the Canadian high Arctic. Accurate and precise measurements of methane are essential to understand quantitatively its role in the climate system and in global change. Here, we show a cross-validation between three datasets: two from spaceborne instruments and one from a ground-based instrument. All are Fourier Transform Spectrometers (FTSs). We consider the Canadian SCISAT Atmospheric Chemistry Experiment (ACE)-FTS, a solar occultation infrared spectrometer operating since 2004, and the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) Thermal And Near infrared Sensor for carbon Observation (TANSO)-FTS, a nadir/off-nadir scanning FTS instrument operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker 125HR Fourier Transform Infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Lab at Eureka, Nunavut (80° N, 86° W) since 2006. For each pair of instruments, measurements are collocated within 500 km and 24 h. An additional criterion based on potential vorticity values was found not to significantly affect differences between measurements. Profiles are regridded to a common vertical grid for each comparison set. To account for differing vertical resolutions, ACE-FTS measurements are smoothed to the resolution of either PEARL-FTS or TANSO-FTS, and PEARL-FTS measurements are smoothed to the TANSO-FTS resolution. Differences for each pair are examined in terms of profile and partial columns. During the period considered, the number of collocations for each pair is large enough to obtain a good sample size (from several hundred to tens of thousands depending on pair and configuration). Considering full profiles, the degrees of freedom for signal (DOFS) are between 0.2 and 0.7 for TANSO-FTS and between 1.5 and 3

  3. Methane cross-validation between three Fourier transform spectrometers: SCISAT ACE-FTS, GOSAT TANSO-FTS, and ground-based FTS measurements in the Canadian high Arctic

    NASA Astrophysics Data System (ADS)

    Holl, Gerrit; Walker, Kaley A.; Conway, Stephanie; Saitoh, Naoko; Boone, Chris D.; Strong, Kimberly; Drummond, James R.

    2016-05-01

    We present cross-validation of remote sensing measurements of methane profiles in the Canadian high Arctic. Accurate and precise measurements of methane are essential to understand quantitatively its role in the climate system and in global change. Here, we show a cross-validation between three data sets: two from spaceborne instruments and one from a ground-based instrument. All are Fourier transform spectrometers (FTSs). We consider the Canadian SCISAT Atmospheric Chemistry Experiment (ACE)-FTS, a solar occultation infrared spectrometer operating since 2004, and the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) Thermal And Near infrared Sensor for carbon Observation (TANSO)-FTS, a nadir/off-nadir scanning FTS instrument operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker 125HR Fourier transform infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Laboratory at Eureka, Nunavut (80° N, 86° W) since 2006. For each pair of instruments, measurements are collocated within 500 km and 24 h. An additional collocation criterion based on potential vorticity values was found not to significantly affect differences between measurements. Profiles are regridded to a common vertical grid for each comparison set. To account for differing vertical resolutions, ACE-FTS measurements are smoothed to the resolution of either PEARL-FTS or TANSO-FTS, and PEARL-FTS measurements are smoothed to the TANSO-FTS resolution. Differences for each pair are examined in terms of profile and partial columns. During the period considered, the number of collocations for each pair is large enough to obtain a good sample size (from several hundred to tens of thousands depending on pair and configuration). Considering full profiles, the degrees of freedom for signal (DOFS) are between 0.2 and 0.7 for TANSO-FTS and

  4. Long-term changes of mercury levels in ringed seal (Phoca hispida) from Amundsen Gulf, and beluga (Delphinapterus leucas) from the Beaufort Sea, western Canadian Arctic.

    PubMed

    Outridge, P M; Hobson, K A; Savelle, J

    2009-11-15

    Mercury (Hg) concentrations were determined in the canine teeth of ringed seals (Phoca hispida) harvested during the 13th-14th, late 19th and early 21st Centuries in Amundsen Gulf, Northwest Territories, Canada. Most historical and pre-industrial teeth contained undetectable Hg levels (i.e. <1.0 ng/g DW), whereas samples from 2001-03 contained up to 12 ng/g DW in an age-dependent pattern. Assuming a median [Hg] value in 13th-14th Century teeth of half the detection limit (i.e. 0.5 ng/g DW), geometric means of Hg in modern teeth were 9-17 times those of seals in the 14th Century, equivalent to an anthropogenic input of 89-94% of total Hg in modern seals. These results corroborate a previous study of beluga (Delphinapterus leucas) in the nearby Beaufort Sea. While the seals' trophic position (inferred from delta(15)N values) did not change over time, modern delta(13)C values were lower by about 2 per thousand than in the 14th and 19th Centuries. This could be due to increased dissolution of anthropogenically derived CO(2) in the ocean from the atmosphere, but could also indicate more offshore pelagic feeding by modern seals, which might be a factor in their Hg exposure. New tooth [Hg] data are also presented for the Beaufort Sea beluga, using recently-discovered museum samples collected in 1960/61, which showed that most of the anthropogenic contribution to beluga Hg had already taken effect by 1960 (reaching approximately 75% of total Hg). Taken together, the long-term seal and beluga data indicate that whereas Hg levels in the marine ecosystems of the western Canadian Arctic were probably unchanged from pre-industrial times up to the late 19th Century, there was a significant, many-fold increase in the early to mid-20th Century, but little or no change after about the early 1960s.

  5. Slope Gullies on Devon Island, Canadian Arctic: Possible Analogs for Gullies on Mars and Evidence for Recent Transient Environmental Change on Mars.

    NASA Astrophysics Data System (ADS)

    Lee, P.

    2002-12-01

    The origin and evolution of the relatively youthful slope gully features on Mars first reported by Malin and Edgett (2000) remain enigmatic. Two prevailing hypotheses concerning their formation involve the discharge of subsurface H2O at the gully sites: groundwater seepage (1) and/or the melting of ground-ice (2, 3). In the course of geologic field investigations on Devon Island, Canadian Arctic, we have identified morphologic and contextual analogs for the martian gullies that result from a radically different mechanism of formation (4). The gullies on Devon result mainly from the episodic melting of transient surface snow and ice deposits, with little contribution from subsurface H2O reservoirs. Timescales for gully formation on Devon Island are ­š104 years (5). The gullies on Devon suggest that the formation of gully features on Mars might not necessarily have involved discharges of subsurface H2O at the gully sites. Instead, gullies on Mars might be the result of transient surface snow and ice melting, which in turn might be the result of short-term changes in regional surface environmental conditions (on time-scales of ­š105-108 years?) possibly in association with high obliquity-induced climate change (6, 7) and/or volcanic activity. Acknowledgements: This research was conducted under the auspices of the NASA Haughton-Mars Project (HMP) with support from NASA and the National Geographic Society. References: (1) Malin, M. C. and K. S. Edgett 2000. Science 288, 2330-2335. (2) Mellon, M. T. and R. J. Phillips 2001. J. Geophys. Res. 106, 23165-23179. (3) Costard, F. et al. 2002. Science 295, 110-112. (4) Lee, P. et al. 2001. LPSC. XXXII, Houston, TX, Mar 12-16, 2001. (5) Lee, P, et al. 2002. LPSC XXXIII, Houston, TX, Mar 11-15, 2002. (6) Ward, W. R. (1973) Science 181, 260-262. (7) Touma, J. and J. Wisdom (1993) Science 259, 1294-1296.

  6. Air quality monitoring in communities of the Canadian Arctic during the high shipping season with a focus on local and marine pollution

    NASA Astrophysics Data System (ADS)

    Aliabadi, A. A.; Staebler, R. M.; Sharma, S.

    2014-11-01

    The Canadian Arctic has experienced decreasing sea ice extent and increasing shipping activity in the recent decades. While there are economic incentives to develop resources in the North, there are environmental concerns that increasing marine traffic will contribute to declining air quality in Northern communities. In an effort to characterize the relative impact of shipping on air quality in the North, two monitoring stations have been installed in Cape Dorset and Resolute, Nunavut, and have been operational since 1 June 2013. The impact of shipping and other sources of emissions on NOx, O3, SO2, BC, and PM2.5 pollution have been characterized for the 2013 shipping season from 1 June to 1 November. In addition, a high resolution Air Quality Health Index (AQHI) for both sites was computed. Shipping consistently increased O3 mixing ratio and PM2.5 concentration. The 90% confidence interval for mean difference in O3 mixing ratio between ship and no ship-influenced air masses were up to 4.6-4.7 ppb and 2.5-2.7 ppb for Cape Dorset and Resolute, respectively. The same intervals for PM2.5 concentrations were up to 1.8-1.9 μg m-3 and 0.5-0.6 μg m-3. Ship-influenced air masses consistently exhibited degraded air quality by an increase of 0.1 to 0.3 in the high resolution AQHI compared to no ship-influenced air masses. Trajectory cluster analysis in combination with ship traffic tracking provided an estimated range for percent ship contribution to NOx, O3, SO2, and PM2.5 that were 12.9-17.5%, 16.2-18.1%, 16.9-18.3%, and 19.5-31.7% for Cape Dorset and 1.0-7.2%, 2.9-4.8%, 5.5-10.0%, and 6.5-7.2% for Resolute during the 2013 shipping season. Additional measurements in Resolute suggested that percent ship contribution to black carbon was 4.3-9.8% and that black carbon constituted 1.3-9.7% of total PM2.5 mass in ship plumes. Continued air quality monitoring in the above sites for future shipping seasons will improve the statistics in our analysis as well as characterize

  7. Air quality monitoring in communities of the Canadian Arctic during the high shipping season with a focus on local and marine pollution

    NASA Astrophysics Data System (ADS)

    Aliabadi, A. A.; Staebler, R. M.; Sharma, S.

    2015-03-01

    The Canadian Arctic has experienced decreasing sea ice extent and increasing shipping activity in recent decades. While there are economic incentives to develop resources in the north, there are environmental concerns that increasing marine traffic will contribute to declining air quality in northern communities. In an effort to characterize the relative impact of shipping on air quality in the north, two monitoring stations have been installed in Cape Dorset and Resolute, Nunavut, and have been operational since 1 June 2013. The impact of shipping and other sources of emissions on NOx, O3, SO2, BC, and PM2.5 pollution have been characterized for the 2013 shipping season from 1 June to 1 November. In addition, a high-resolution Air Quality Health Index (AQHI) for both sites was computed. Shipping consistently increased O3 mixing ratio and PM2.5 concentration. The 90% confidence interval for mean difference in O3 mixing ratio between ship- and no ship-influenced air masses were up to 4.6-4.7 ppb and 2.5-2.7 ppb for Cape Dorset and Resolute, respectively. The same intervals for PM2.5 concentrations were up to 1.8-1.9 μg m-3 and 0.5-0.6 μg m-3. Ship-influenced air masses consistently exhibited an increase of 0.1 to 0.3 in the high-resolution AQHI compared to no ship-influenced air masses. Trajectory cluster analysis in combination with ship traffic tracking provided an estimated range for percent ship contribution to NOx, O3, SO2, and PM2.5 that were 12.9-17.5 %, 16.2-18.1 %, 16.9-18.3 %, and 19.5-31.7 % for Cape Dorset and 1.0-7.2 %, 2.9-4.8 %, 5.5-10.0 %, and 6.5-7.2 % for Resolute during the 2013 shipping season. Additional measurements in Resolute suggested that percent ship contribution to black carbon was 4.3-9.8 % and that black carbon constituted 1.3-9.7 % of total PM2.5 mass in ship plumes. Continued air quality monitoring in the above sites for future shipping seasons will improve the statistics in our analysis and characterize repeating seasonal patterns

  8. Paleo-environmental gateways in the eastern Canadian arctic - Recent isotope hydrology and diatom oxygen isotopes from Nettilling Lake, Baffin Island, Canada

    NASA Astrophysics Data System (ADS)

    Chapligin, B.; Narancic, B.; Meyer, H.; Pienitz, R.

    2016-09-01

    Nettilling Lake is located on Baffin Island, Nunavut, Canada between the areas of past warming (Canadian High Arctic to the North) and climatic stability (Northern Quebec and Labrador region to the South). Despite being the largest lake in the Nunavut region with a postglacial marine to lacustrine transition history only a few paleo-environmental investigations were completed in this area. The oxygen isotope composition of diatoms (δ18Odiatom) can provide valuable insights into paleo-environmental conditions. Here, the recent (isotope) hydrology and hydrochemical data from the lake are presented to facilitate the interpretation of a δ18Odiatom record from an 82 cm sediment core (Ni-2B). The well-mixed lake (δ18Owater = -17.4‰) is influenced by a heavier (less negative) isotope composition (-18.80‰) from Amadjuak River draining Amadjuak Lake to the South and water of lighter (more negative) isotopic composition (-16.4‰) from the Isurtuq River originating from Penny Ice Cap in the North-East. From the δ18Owater and δ18Odiatom of the topmost sample of core Ni-2B a Δ18Osilica-water of 1000 ln α(silica-water) = 40.2‰ for sub-recent diatoms of Nettilling Lake was calculated matching the known water-silica fractionation for fossil sediments well and thereby showing the general applicability of this proxy for paleo-reconstructions in this region. Extremely large δ18Odiatom variations in the core of more than 13‰ are mainly induced by changes in the isotopic composition of the lake water due to a shift from glaciomarine (δ18Odiatom = +34.6‰) through brackish (+23.4 to +27.2‰) towards lacustrine (+21.5‰) conditions (transition zones glaciomarine to brackish at 69 cm/7300 yr cal. BP and brackish to lacustrine at 35 cm/6000 yr cal. BP) associated with a shift in the degree of salinity. Our study provides the first evidence that paleo-salinity can be reconstructed by δ18Odiatom. Additionally, for the lacustrine section it could be demonstrated that

  9. On the formulation of sea-ice models. Part 2: Lessons from multi-year adjoint sea-ice export sensitivities through the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Heimbach, Patick; Menemenlis, Dimitris; Losch, Martin; Campin, Jean-Michel; Hill, Chris

    The adjoint of an ocean general circulation model is at the heart of the ocean state estimation system of the Estimating the Circulation and Climate of the Ocean (ECCO) project. As part of an ongoing effort to extend ECCO to a coupled ocean/sea-ice estimation system, a dynamic and thermodynamic sea-ice model has been developed for the Massachusetts Institute of Technology general circulation model (MITgcm). One key requirement is the ability to generate, by means of automatic differentiation (AD), tangent linear (TLM) and adjoint (ADM) model code for the coupled MITgcm ocean/sea-ice system. This second part of a two-part paper describes aspects of the adjoint model. The adjoint ocean and sea-ice model is used to calculate transient sensitivities of solid (ice and snow) freshwater export through Lancaster Sound in the Canadian Arctic Archipelago (CAA). The adjoint state provides a complementary view of the dynamics. In particular, the transient, multi-year sensitivity patterns reflect dominant pathways and propagation timescales through the CAA as resolved by the model, thus shedding light on causal relationships, in the model, across the Archipelago. The computational cost of inferring such causal relationships from forward model diagnostics alone would be prohibitive. The role of the exact model trajectory around which the adjoint is calculated (and therefore of the exactness of the adjoint) is exposed through calculations using free-slip vs no-slip lateral boundary conditions. Effective ice thickness, sea surface temperature, and precipitation sensitivities, are discussed in detail as examples of the coupled sea-ice/ocean and atmospheric forcing control space. To test the reliability of the adjoint, finite-difference perturbation experiments were performed for each of these elements and the cost perturbations were compared to those "predicted" by the adjoint. Overall, remarkable qualitative and quantitative agreement is found. In particular, the adjoint correctly

  10. Long-term changes of mercury levels in ringed seal (Phoca hispida) from Amundsen Gulf, and beluga (Delphinapterus leucas) from the Beaufort Sea, western Canadian Arctic.

    PubMed

    Outridge, P M; Hobson, K A; Savelle, J

    2009-11-15

    Mercury (Hg) concentrations were determined in the canine teeth of ringed seals (Phoca hispida) harvested during the 13th-14th, late 19th and early 21st Centuries in Amundsen Gulf, Northwest Territories, Canada. Most historical and pre-industrial teeth contained undetectable Hg levels (i.e. <1.0 ng/g DW), whereas samples from 2001-03 contained up to 12 ng/g DW in an age-dependent pattern. Assuming a median [Hg] value in 13th-14th Century teeth of half the detection limit (i.e. 0.5 ng/g DW), geometric means of Hg in modern teeth were 9-17 times those of seals in the 14th Century, equivalent to an anthropogenic input of 89-94% of total Hg in modern seals. These results corroborate a previous study of beluga (Delphinapterus leucas) in the nearby Beaufort Sea. While the seals' trophic position (inferred from delta(15)N values) did not change over time, modern delta(13)C values were lower by about 2 per thousand than in the 14th and 19th Centuries. This could be due to increased dissolution of anthropogenically derived CO(2) in the ocean from the atmosphere, but could also indicate more offshore pelagic feeding by modern seals, which might be a factor in their Hg exposure. New tooth [Hg] data are also presented for the Beaufort Sea beluga, using recently-discovered museum samples collected in 1960/61, which showed that most of the anthropogenic contribution to beluga Hg had already taken effect by 1960 (reaching approximately 75% of total Hg). Taken together, the long-term seal and beluga data indicate that whereas Hg levels in the marine ecosystems of the western Canadian Arctic were probably unchanged from pre-industrial times up to the late 19th Century, there was a significant, many-fold increase in the early to mid-20th Century, but little or no change after about the early 1960s. PMID:19766293

  11. The use of airborne radar reflectometry to characterize near-surface snow/firn stratigraphy on Devon Ice Cap, Canadian Arctic: A path to identifying refrozen melt layers

    NASA Astrophysics Data System (ADS)

    Rutishauser, A.; Grima, C.; Sharp, M. J.; Blankenship, D. D.; Young, D. A.; Dowdeswell, J. A.

    2015-12-01

    Under present warming conditions, summer surface melt has been observed to intensify and shift towards higher elevations in the accumulation zones of Canadian Arctic ice caps. Consequently, more meltwater percolates into the near surface snow and firn, and refreezes as ice layers. This process can lead to a significant increase in firn densification rates. Knowledge of spatiotemporal variations of the near-surface firn density, especially the distribution of ice layer formation is of great importance when assessing mass change estimates from repeat altimetry measurements. Here, we present an approach for characterizing the near-surface firn stratigraphy and determining the spatial distribution of refrozen melt layers on Devon Ice Cap, using the surface echo from airborne radio-echo sounding (RES) measurements. The RES surface echo is affected by the upper few meters of snow/firn/ice and thus contains information about the near-surface properties. More specifically, the radar surface return is a combination of a coherent (Pc) and a scattering signal component (Pn). Pc is related to the dielectric constant of the probed surface, whereas Pn is related to the near surface roughness. Hence, different near-surface snow/firn properties can be investigated by analyzing the signal components Pc and Pn and their spatial variability. The Radar Statistical Reconnaissance (RSR) methodology [1] allows the extraction of Pc and Pn from the surface radar return, which then can be used to compute near-surface roughness and firn density estimates. We apply the RSR method to RES data collected on Devon Ice Cap and determine Pc and Pn values. We then compare the results to ground based RES measurements and shallow firn cores (~11 m deep) collected along the airborne RES flight lines. This comparison shows that variations in the scattering coefficient Pn correlate to changes in the pattern of near-surface firn stratigraphy revealed by the ground based RES data and firn cores. Based on

  12. Arctic Watch

    NASA Astrophysics Data System (ADS)

    Orcutt, John; Baggeroer, Arthur; Mikhalevsky, Peter; Munk, Walter; Sagen, Hanne; Vernon, Frank; Worcester, Peter

    2015-04-01

    The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This will be driven by increased demand for energy and the marine resources of an Arctic Ocean more accessible to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism and search and rescue will increase the pressure on the vulnerable Arctic environment. Synoptic in-situ year-round observational technologies are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual and decadal scales to inform and enable sustainable development and enforcement of international Arctic agreements and treaties, while protecting this critical environment. This paper will discuss multipurpose acoustic networks, including subsea cable components, in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic and anthropogenic), and acoustic remote sensing (tomography and thermometry), supporting and complementing data collection from platforms, moorings and autonomous vehicles. This paper supports the development and implementation of regional to basin-wide acoustic networks as an integral component of a multidisciplinary, in situ Arctic Ocean Observatory.

  13. Geochemical haloes as an indication of over oil and gas fields in the Arctic shelf

    NASA Astrophysics Data System (ADS)

    Kholmiansky, Mikhail; Anokhin, Vladimir

    2013-04-01

    Hydrocarbon deposits at the Arctic shelf of Russia are a source of jet dispersion of heavy metals that forms haloes in sediments and in the bottom layer of sea water. The intensity of the haloes and their spatial position are jointly determined by geological structure of their source and the environment, i.e., hydrocarbon deposits in host rocks, seafloor lithodynamics and oceanographic factors. Based on theoretical works of Kholmyansky and Putikov (2000; 2006; 2008), an application of electrochemical modification of electric prospecting for offshore hydrocarbon exploration and detailed survey of the morphology of deposits was developed. Specialized equipment was developed for studies of electrochemical features of bottom water layer. With this equipment one can detect ion anomalies in water and determine the type of deposit as gas, gas hydrate, gas condensate or oil. At operation, the unit with equipment is towed underwater off the stern of research vessel. Type and configuration of deposits are determined based on occurrence of trace heavy metals detected by ion-selective electrodes. The proposed method was applied to study a few hydrocarbon fields in Barents and Kara seas in 2001 -2012 including Shtokman, Medyn, Polyarnoe, Prirazlomnoye and others. The results allowed us to trace the margins of the deposits in more detail, and geochemical data, in addition, showed the type of deposits. In general, the method has proven efficient and applicable to a wide range of hydrocarbon deposits.

  14. Engineering and Economics of the USGS Circum-Arctic Oil and Gas Resource Appraisal (CARA) Project

    USGS Publications Warehouse

    Verma, Mahendra K.; White, Loring P.; Gautier, Donald L.

    2008-01-01

    This Open-File report contains illustrative materials, in the form of PowerPoint slides, used for an oral presentation given at the Fourth U.S. Geological Survey Workshop on Reserve Growth of petroleum resources held on March 10-11, 2008. The presentation focused on engineering and economic aspects of the Circum-Arctic Oil and Gas Resource Appraisal (CARA) project, with a special emphasis on the costs related to the development of hypothetical oil and gas fields of different sizes and reservoir characteristics in the North Danmarkshavn Basin off the northeast coast of Greenland. The individual PowerPoint slides highlight the topics being addressed in an abbreviated format; they are discussed below, and are amplified with additional text as appropriate. Also included in this report are the summary results of a typical ?run? to generate the necessary capital and operating costs for the development of an offshore oil field off the northeast coast of Greenland; the data are displayed in MS Excel format generated using Questor software (IHS Energy, Inc.). U.S. Geological Survey (USGS) acknowledges that this report includes data supplied by IHS Energy, Inc.; Copyright (2008) all rights reserved. IHS Energy has granted USGS the permission to publish this report.

  15. Satellite observation of pollutant emissions from gas flaring activities near the Arctic

    NASA Astrophysics Data System (ADS)

    Li, Can; Hsu, N. Christina; Sayer, Andrew M.; Krotkov, Nickolay A.; Fu, Joshua S.; Lamsal, Lok N.; Lee, Jaehwa; Tsay, Si-Chee

    2016-05-01

    Gas flaring is a common practice in the oil industry that can have significant environmental impacts, but has until recently been largely overlooked in terms of relevance to climate change. We utilize data from various satellite sensors to examine pollutant emissions from oil exploitation activities in four areas near the Arctic. Despite the remoteness of these sparsely populated areas, tropospheric NO2 retrieved from the Ozone Monitoring Instrument (OMI) is substantial at ˜1 × 1015 molecules cm-2, suggesting sizeable emissions from these industrial activities. Statistically significant (at the 95% confidence level, corresponding uncertainties in parentheses) increasing trends of 0.017 (±0.01) × 1015 and 0.015 (±0.006) × 1015 molecules cm-2 year-1 over 2004-2015 were found for Bakken (USA) and Athabasca (Canada), two areas having recently experienced fast expansion in the oil industry. This rapid change has implications for emission inventories, which are updated less frequently. No significant trend was found for the North Sea (Europe), where oil production has been declining since the 1990s. For northern Russia, the trend was just under the 95% significance threshold at 0.0057 (±0.006) × 1015 molecules cm-2 year-1. This raises an interesting inconsistency as prior studies have suggested that, in contrast to the continued, albeit slow, expansion of Russian oil/gas production, gas flaring in Russia has decreased in recent years. However, only a fraction of oil fields in Russia were covered in our analysis. Satellite aerosol optical depth (AOD) data revealed similar tendencies, albeit at a weaker level of statistical significance, due to the longer lifetime of aerosols and contributions from other sources. This study demonstrates that synergetic use of data from multiple satellite sensors can provide valuable information on pollutant emission sources that is otherwise difficult to acquire.

  16. Introduction to the eastern Arctic Marine Environmental Studies Program

    SciTech Connect

    Sutterlin, N.; Snow, N.

    1982-01-01

    Main problems are formulated and a study technique is characterized for the environmental protection program (EPP) of the eastern marine area of the Canadian Arctic in the area of physical-geographical (oceanography, meteorology, geomorphology) and biological sciences (microbiology, phytoand zooplankton, benthos, fish, birds and mammals, including white bear) which will be implemented in relation to realization of the extensive plans examined by the Canadian government back in 1977 for development of the large oil and gas resources of this part of the country. With regard for the severity of the ice and climate situation, it is planned to conduct studies of the EPP in the Canadian Arctic with the use of the entire modern scientific and technical potential, from ships and radar units to Earth satellites. Financing and supervision of the research on the EPP come from the government of the country, academic organizations and private firms. The research results will be published by the company Petro-Canada under the title ''Arctic.''

  17. Total mercury in snow and ice samples from Canadian High Arctic ice caps and glaciers: a practical procedure and method for total Hg quantification at low pg g(-1) level.

    PubMed

    Zheng, Jiancheng; Pelchat, Pierre; Vaive, Judy; Bass, David; Ke, Fu

    2014-01-15

    A newly developed procedure and method for studying total Hg (THg) in the High Arctic glaciers and ice caps, including container type selection, on-site sampling, sample protection and storage, and sample decontamination is reported in this study. Two analytical systems for THg quantification were also compared to confirm the accuracy and reproducibility. This study found that container types, storage time, sample protection from exposure to light and environment are all important for precise quantification of THg in snow and ice samples from the Canadian High Arctic glaciers and ice caps. With this newly developed procedure and method, we retrieved 28-year and 73-year archives for atmospheric THg deposition from Mt. Oxford and Agassiz Ice Cap respectively. Our results show that snow and ice samples contain THg concentrations varying from sub pg g(-1) to low pg g(-1). Comparison of THg concentration trends and fluxes from the two sites demonstrates that quantification of THg from the two locations with similar altitudes and latitudes can be reproducible, which suggests that historical THg information from atmospheric deposition can be preserved in snow and ice in the glaciers and ice caps. The high reproducibility of results achieved by this procedure and method, in return, confirmed its suitability for studies of THg in snow and ice samples from ice caps and glaciers.

  18. Research projects needed for expediting development of domestic oil and gas resources through arctic, offshore, and drilling technology

    SciTech Connect

    Canja, S.; Williams, C.R.

    1982-04-01

    This document contains the research projects which were identified at an industry-government workshop on Arctic, Offshore, and Drilling Technology (AODT) held at Bartlesville Energy Technology Center, January 5-7, 1981. The purpose of the workshop was to identify those problem areas where government research could provide technology advancement that would assist industry in accelerating the discovery and development of US oil and gas resouces. The workshop results are to be used to guide an effective research program. The workshop identified and prioritized the tasks that need to be implemented. All of the projects listed in the Arctic and Offshore sections were selected as appropriate for a Department of Energy (DOE) research role. The drilling projects identified as appropriate only for industry research have been separated in the Drilling section of this report.

  19. Arctic stream processes--an annotated bibliography

    USGS Publications Warehouse

    Scott, Kevin M.

    1979-01-01

    This bibliography selectively summarizes investigations to date (1978) dealing with the physical processes of streams in the Arctic. The specialized annotations include aspects of stream processes described in subordinate parts of general papers on the arctic environment and therefore not evident in author-abstract bibliographies. Foreign contributions--Canadian, Scandinavian, and Russian--are summarized, in the case of Russian literature primarily by means of papers in translation journals. Until 1970 the role of streams in development of the arctic landscape was commonly considered subordinate to that of glacial and frost-related processes. This conclusion changed, however, with the findings of the many new studies begun in response to oil and gas discoveries in the late 1960's. The conclusions of these studies, made to provide both the engineering data for resource development and the information to assess the impacts of that development, were in general agreement that stream processes throughout most of the Arctic were significantly more important than previously had been thought.

  20. Satellite observation of pollutant emissions from gas flaring activities near the Arctic

    NASA Astrophysics Data System (ADS)

    Li, Can; Hsu, N. Christina; Sayer, Andrew M.; Krotkov, Nickolay A.; Fu, Joshua S.; Lamsal, Lok N.; Lee, Jaehwa; Tsay, Si-Chee

    2016-05-01

    Gas flaring is a common practice in the oil industry that can have significant environmental impacts, but has until recently been largely overlooked in terms of relevance to climate change. We utilize data from various satellite sensors to examine pollutant emissions from oil exploitation activities in four areas near the Arctic. Despite the remoteness of these sparsely populated areas, tropospheric NO2 retrieved from the Ozone Monitoring Instrument (OMI) is substantial at ∼1 × 1015 molecules cm-2, suggesting sizeable emissions from these industrial activities. Statistically significant (at the 95% confidence level, corresponding uncertainties in parentheses) increasing trends of 0.017 (±0.01) × 1015 and 0.015 (±0.006) × 1015 molecules cm-2 year-1 over 2004-2015 were found for Bakken (USA) and Athabasca (Canada), two areas having recently experienced fast expansion in the oil industry. This rapid change has implications for emission inventories, which are updated less frequently. No significant trend was found for the North Sea (Europe), where oil production has been declining since the 1990s. For northern Russia, the trend was just under the 95% significance threshold at 0.0057 (±0.006) × 1015 molecules cm-2 year-1. This raises an interesting inconsistency as prior studies have suggested that, in contrast to the continued, albeit slow, expansion of Russian oil/gas production, gas flaring in Russia has decreased in recent years. However, only a fraction of oil fields in Russia were covered in our analysis. Satellite aerosol optical depth (AOD) data revealed similar tendencies, albeit at a weaker level of statistical significance, due to the longer lifetime of aerosols and contributions from other sources. This study demonstrates that synergetic use of data from multiple satellite sensors can provide valuable information on pollutant emission sources that is otherwise difficult to acquire.

  1. Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms, (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the Central Canadian Arctic

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of both these lungworms have a characteristic dorsal spine originating at the level of proxima...

  2. A 50 % increase in the mass of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Devred, E.; Babin, M.

    2015-06-01

    Global warming has a significant impact on the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitation along the drainage basins of Arctic rivers. It has also directly impacted land and seawater temperatures with the consequence of melting permafrost and sea ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which has been sequestered in a frozen state since the Last Glacial Maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean color satellite data and field observations collected in 2009 to estimate the mass of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period, the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

  3. A 50% increase in the amount of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Devred, E.; Babin, M.

    2015-01-01

    Global warming has a significant impact at the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitations along the drainage basins of Arctic Rivers. It has also directly impacted land and seawater temperatures with the consequence of melting the permafrost and sea-ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which was sequestered as frozen since the last glacial maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean-colour satellite data and field observations collected in 2009 to estimate the amount of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

  4. Stratospheric Aerosol and Gas Experiment (SAGE) II and III Aerosol Extinction Measurements in the Arctic Middle and Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Treffeisen, R. E.; Thomason, L. W.; Strom, J.; Herber, A. B.; Burton, S. P.; Yamanouchi, T.

    2006-01-01

    In recent years, substantial effort has been expended toward understanding the impact of tropospheric aerosols on Arctic climate and chemistry. A significant part of this effort has been the collection and documentation of extensive aerosol physical and optical property data sets. However, the data sets present significant interpretive challenges because of the diverse nature of these measurements. Among the longest continuous records is that by the spaceborne Stratospheric Aerosol and Gas Experiment (SAGE) II. Although SAGE tropospheric measurements are restricted to the middle and upper troposphere, they may be able to provide significant insight into the nature and variability of tropospheric aerosol, particularly when combined with ground and airborne observations. This paper demonstrates the capacity of aerosol products from SAGE II and its follow-on experiment SAGE III to describe the temporal and vertical variations of Arctic aerosol characteristics. We find that the measurements from both instruments are consistent enough to be combined. Using this combined data set, we detect a clear annual cycle in the aerosol extinction for the middle and upper Arctic troposphere.

  5. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing

    PubMed Central

    Marshall, John; Armour, Kyle C.; Scott, Jeffery R.; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G.; Bitz, Cecilia M.

    2014-01-01

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around ‘climate response functions’ (CRFs), i.e. the response of the climate to ‘step’ changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an

  6. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.

    PubMed

    Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

    2014-07-13

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate

  7. Baseline monitoring of the western Arctic Ocean estimates 20% of the Canadian Basin surface waters are undersaturated with respect to aragonite

    USGS Publications Warehouse

    Robbins, Lisa L.; Wynn, Jonathan G.; Lisle, John T.; Yates, Kimberly K.; Knorr, Paul O.; Byrne, Robert H.; Liu, Xuewu; Patsavas, Mark C.; Azetsu-Scott, Kumiko; Takahashi, Taro

    2013-01-01

    Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ~20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean’s largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

  8. Microbes residing in young organic rich Alaskan soils contain older carbon than those residing in old mineral high Arctic soils

    NASA Astrophysics Data System (ADS)

    Ziolkowski, L. A.; Slater, G. F.; Onstott, T. C.; Whyte, L.; Townsend-Small, A.

    2013-12-01

    in Alaskan soil than that of the Canadian high Arctic soil, indicating that Alaskan microbes were interacting with the bulk organic carbon pool and Canadian high Arctic soil microbes were disconnected from the bulk organic carbon pool. Additionally, dissimilarities in the n-alkane distributions suggest vastly different carbon sources to these different soils. Collectively, these results suggest that (a) these Arctic soils contain a comparable abundance of microbes, (b) the organic carbon being accumulated in the Alaskan soil is likely from recent biomass, (c) mineral soil accumulation in the Canadian high Arctic is likely due to erosional inputs of ancient carbon and (d) the carbon stocks in Alaskan soils are more bioavailable to the microbes than those in mineral soils of the Canadian high Arctic. Incubation studies that incorporate gas fluxes and proteomics may tease apart if the observed differences in bioavailability are a function of temperature, substrate availability or some other variable.

  9. Trace Gas Transport in the Arctic Vortex Inferred from ATMOS ATLAS-2 Observations During April 1993

    NASA Technical Reports Server (NTRS)

    Abrams, M. C.; Manney, G. L.; Gunson, M. R.; Abbas, M. M.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C, P,; Salawitch, R. J.; Stiller, G. P.; Zander, R.

    1996-01-01

    Measurements of the long-lived tracers CH4, N2O, and HF from the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the Atmospheric Laboratory for Science and Applications-2 (ATLAS-2) Space Shuttle mission in April 1993 are used to infer average winter descent rates ranging from 0.8 km/month at 20 km to 3.2 km/month at 40 km in the Arctic polar vortex during the 1992-93 winter. Descent rates in the mid-stratosphere are similar to those deduced for the Antarctic vortex using ATMOS/ATLAS-3 measurements in November 1994, but the shorter time period of descent in the Arctic leads to smaller total distances of descent. Strong horizontal gradients observed along the vortex edge indicate that the Arctic vortex remains a significant barrier to transport at least until mid-April in the lower to middle stratosphere.

  10. Arctic lakes and streams as gas conduits to the atmosphere: Implications for tundra carbon budgets

    SciTech Connect

    Kling, G.W. ); Kipphut, G.W. ); Miller, M.C. )

    1991-01-01

    Arctic tundra has large amounts of stored carbon and is thought to be a sink for atmospheric carbon dioxide (CO{sub 2}) (0.1 to 0.3 petagram of carbon per year) (1 petagram = 10{sup 15} grams). But this estimate of carbon balance is only for terrestrial ecosystems. Measurements of the partial pressure of CO{sub 2} in 29 aquatic ecosystems across arctic Alaska showed that in most cases (27 of 29) CO{sub 2} was released to the atmosphere. This CO{sub 2} probably originates in terrestrial environments; erosion of particulate carbon plus ground-water transport of dissolved carbon from tundra contribute to the CO{sub 2} flux from surface waters to the atmosphere. If this mechanism is typical of that of other tundra areas, then current estimates of the arctic terrestrial sink for atmospheric CO{sub 2} may be 20 percent too high. 1 table, 2 figs., 21 refs.

  11. Arctic Economics Model

    1995-03-01

    AEM (Arctic Economics Model) for oil and gas was developed to provide an analytic framework for understanding the arctic area resources. It provides the capacity for integrating the resource and technology information gathered by the arctic research and development (R&D) program, measuring the benefits of alternaive R&D programs, and providing updated estimates of the future oil and gas potential from arctic areas. AEM enables the user to examine field or basin-level oil and gas recovery,more » costs, and economics. It provides a standard set of selected basin-specified input values or allows the user to input their own values. AEM consists of five integrated submodels: geologic/resource submodel, which distributes the arctic resource into 15 master regions, consisting of nine arctic offshore regions, three arctic onshore regions, and three souhtern Alaska (non-arctic) regions; technology submodel, which selects the most appropriate exploration and production structure (platform) for each arctic basin and water depth; oil and gas production submodel, which contains the relationship of per well recovery as a function of field size, production decline curves, and production decline curves by product; engineering costing and field development submodel, which develops the capital and operating costs associated with arctic oil and gas development; and the economics submodel, which captures the engineering costs and development timing and links these to oil and gas prices, corporate taxes and tax credits, depreciation, and timing of investment. AEM provides measures of producible oil and gas, costs, and ecomonic viability under alternative technology or financial conditions.« less

  12. Non-nuclear submarine tankers could cost-effectively move Arctic oil and gas

    SciTech Connect

    Kumm, W.H.

    1984-03-05

    Before the advent of nuclear propulsion for U.S. Navy submarines, fuel cells were considered to be the next logical step forward from battery powered submarines which required recharging. But with the launching of the USS Nautilus (SSN-571) in 1954, the development of fuel-cell propulsion was sidelined by the naval community. Nearly 30 years later fuel-cell propulsion on board submarines is actually more cost-effective than the use of nuclear propulsion. In the Artic Ocean, the use of the submarine tanker has long been considered commercially appropriate because of the presence of the polar ice cap, which inhibits surface ship transport. The technical difficulty and high operating cost of Arctic icebreaking tankers are strong arguments in favor of the cheaper, more efficient submarine tanker. Transiting under the polar ice cap, the submarine tanker is not an ''Arctic'' system, but merely a submerged system. It is a system usable in any ocean around the globe where sufficient depth exists (about 65% of the global surface). Ice breakers are another story; their design only makes them useful for transit through heavy sea ice in coastal environments. Used anywhere else, such as in the open ocean or at the Arctic ice cap, they are not a cost-effective means of transport. Arctic sea ice conditions require the Arctic peculiar icebreaking tanker system to do the job the hard way-on the surface. But on the other hand, Arctic sea ice conditions are neatly set aside by the submarine tanker, which does it the energy-efficient, elegant way submerged. The submarine tanker is less expensive to build, far less expensive to operate, and does not need to be nuclear propelled.

  13. Geochemical and Sr-Nd isotope variations within Cretaceous continental flood-basalt suites of the Canadian High Arctic, with a focus on the Hassel Formation basalts of northeast Ellesmere Island

    NASA Astrophysics Data System (ADS)

    Estrada, Solveig

    2015-11-01

    Early- to mid-Cretaceous flood-basalt suites of the northeast Canadian High Arctic assigned to a High Arctic Large Igneous Province (HALIP) were studied for their whole-rock geochemistry and Sr-Nd isotopes. Data from basalt flows within the upper Albian to lower Cenomanian Hassel Formation of northeast Ellesmere Island are compared with former published data and new inductively coupled plasma mass spectrometry data of the stratigraphic equivalent Strand Fiord basalts and the older, late Hauterivian to Aptian Isachsen basalts from Axel Heiberg Island. The transitional to mildly alkaline aphyric Hassel basalts, with ocean island basalt (OIB)-like geochemical signatures in parts, have an Ar-Ar whole-rock age of on average 96.4 ± 1.6 Ma. They represent two geochemically different flow units without a fractional crystallization relationship: the high-phosphorous (HP) and low-phosphorous (LP) basalts. The Hassel HP basalts differ from the LP basalts by additionally higher Ba, K, Rb, Th and LREE contents, a pronounced positive Eu anomaly (Eu/Eu* = 1.74-1.76), as well as lower Ta, Nb, Zr and Hf concentrations. The Nd and Sr isotope ratios of the Hassel HP basalts [ ɛ Nd( t) of -1.3 to -1.4, 87Sr/86Sr( t) of 0.70706-0.70707] and the LP basalts [ ɛ Nd( t) of 4.5-4.9, 87Sr/86Sr( t) of 0.7038-0.7040] indicate an origin from different mantle sources. The geochemically similar tholeiitic Isachsen (ca. 130-113 Ma) and Strand Fiord basalts (ca. 105-95 Ma) are also incompatible element enriched relative to the primitive mantle, however, with negative Sr-P anomalies as well as partially negative K, Ta and Nb anomalies. In terms of incompatible element ratios (Zr/Nb, Nb/Th), several mantle components are involved in the formation of the flood-basalt suites: a component with primitive mantle composition, an OIB-like component (probably subducted and recycled oceanic crust) and an enriched lithospheric component. The latter component, probably metasomatized subcontinental

  14. U.S. Geological Survery Oil and Gas Resource Assessment of the Russian Arctic

    SciTech Connect

    Donald Gautier; Timothy Klett

    2008-12-31

    The U.S. Geological Survey (USGS) recently completed a study of undiscovered petroleum resources in the Russian Arctic as a part of its Circum-Arctic Resource Appraisal (CARA), which comprised three broad areas of work: geological mapping, basin analysis, and quantitative assessment. The CARA was a probabilistic, geologically based study that used existing USGS methodology, modified somewhat for the circumstances of the Arctic. New map compilation was used to identify assessment units. The CARA relied heavily on geological analysis and analog modeling, with numerical input consisting of lognormal distributions of sizes and numbers of undiscovered accumulations. Probabilistic results for individual assessment units were statistically aggregated, taking geological dependencies into account. The U.S. Department of Energy (DOE) funds were used to support the purchase of crucial seismic data collected in the Barents Sea, East Siberian Sea, and Chukchi Sea for use by USGS in its assessment of the Russian Arctic. DOE funds were also used to purchase a commercial study, which interpreted seismic data from the northern Kara Sea, and for geographic information system (GIS) support of USGS mapping of geological features, province boundaries, total petroleum systems, and assessment units used in the USGS assessment.

  15. Stock origins of Dolly Varden collected from Beaufort Sea coastal sites of Arctic Alaska and Canada

    USGS Publications Warehouse

    Krueger, C.C.; Wilmot, R.L.; Everett, R.J.

    1999-01-01

    Anadromous northern Dolly Varden Salvelinus malma support a summer subsistence fishery in Beaufort Sea coastal waters. These same waters coincide with areas of oil and gas exploration and development. The purpose of this study was to assess variation in stock origins of Dolly Varden collected from sites along 400 km of Beaufort Sea coast. Mixed-stock analyses (MSA) of allozyme data were used to compare collections from four sites (Endicolt near Prudhoe Bay, Mikkelsen Bay, and Kaktovik in Alaska and Phillips Bay in Canada) and to assess variation in stock contributions among summer months and between 1987 and 1988. The MSA estimates for individual stocks were summed into estimates for three stock groups: western stocks from the area near Sagavarnirktok River and Prudhoe Bay (SAG), Arctic National Wildlife Refuge stocks (Arctic Refuge), and Canadian stocks. The MSA of Endicott samples taken in 1987 and 1988 did not differ among months in terms of contributions from local SAG stocks (range, 71-95%). Contributions from nonlocal (>100 km distant) Canadian and Arctic Refuge stocks were not different from zero in 1987, but contributions from Canadian stocks were so in July (17%) and August (20%) but not in September of 1988. Thus, stock contributions to Endicott collections were different between 1987 and 1988. Samples from the Kaktovik area in 1988 were different between months in terms of contributions from nonlocal SAG stocks (July, 7%; August, 27%). Significant contributions to these samples were made both months by Canadian (25% and 17%) and local Arctic Refuge stocks (68% and 56%). Among the four coastal sites, local stocks typically contributed most to collections; however, every site had collections that contained significant contributions from nonlocal stocks. The MSA estimates clearly revealed the movement of Dolly Varden between U.S. and Canada coastal waters. If local stocks are affected by oil and gas development activities, distant subsistence fisheries

  16. Utilization of fluorescent microspheres and a green fluorescent protein-marked strain for assessment of microbiological contamination of permafrost and ground ice core samples from the Canadian High Arctic.

    PubMed

    Juck, D F; Whissell, G; Steven, B; Pollard, W; McKay, C P; Greer, C W; Whyte, L G

    2005-02-01

    Fluorescent microspheres were applied in a novel fashion during subsurface drilling of permafrost and ground ice in the Canadian High Arctic to monitor the exogenous microbiological contamination of core samples obtained during the drilling process. Prior to each drill run, a concentrated fluorescent microsphere (0.5-microm diameter) solution was applied to the interior surfaces of the drill bit, core catcher, and core tube and allowed to dry. Macroscopic examination in the field demonstrated reliable transfer of the microspheres to core samples, while detailed microscopic examination revealed penetration levels of less than 1 cm from the core exterior. To monitor for microbial contamination during downstream processing of the permafrost and ground ice cores, a Pseudomonas strain expressing the green fluorescent protein (GFP) was painted on the core exterior prior to processing. Contamination of the processed core interiors with the GFP-expressing strain was not detected by culturing the samples or by PCR to detect the gfp marker gene. These methodologies were quick, were easy to apply, and should help to monitor the exogenous microbiological contamination of pristine permafrost and ground ice samples for downstream culture-dependent and culture-independent microbial analyses.

  17. Utilization of Fluorescent Microspheres and a Green Fluorescent Protein-Marked Strain for Assessment of Microbiological Contamination of Permafrost and Ground Ice Core Samples from the Canadian High Arctic

    PubMed Central

    Juck, D. F.; Whissell, G.; Steven, B.; Pollard, W.; McKay, C. P.; Greer, C. W.; Whyte, L. G.

    2005-01-01

    Fluorescent microspheres were applied in a novel fashion during subsurface drilling of permafrost and ground ice in the Canadian High Arctic to monitor the exogenous microbiological contamination of core samples obtained during the drilling process. Prior to each drill run, a concentrated fluorescent microsphere (0.5-μm diameter) solution was applied to the interior surfaces of the drill bit, core catcher, and core tube and allowed to dry. Macroscopic examination in the field demonstrated reliable transfer of the microspheres to core samples, while detailed microscopic examination revealed penetration levels of less than 1 cm from the core exterior. To monitor for microbial contamination during downstream processing of the permafrost and ground ice cores, a Pseudomonas strain expressing the green fluorescent protein (GFP) was painted on the core exterior prior to processing. Contamination of the processed core interiors with the GFP-expressing strain was not detected by culturing the samples or by PCR to detect the gfp marker gene. These methodologies were quick, were easy to apply, and should help to monitor the exogenous microbiological contamination of pristine permafrost and ground ice samples for downstream culture-dependent and culture-independent microbial analyses. PMID:15691963

  18. Deformation and the timing of gas generation and migration in the eastern Brooks Range foothills, Arctic National Wildlife Refuge, Alaska

    USGS Publications Warehouse

    Parris, T.M.; Burruss, R.C.; O'Sullivan, P. B.

    2003-01-01

    Along the southeast border of the 1002 Assessment Area in the Arctic National Wildlife Refuge, Alaska, an explicit link between gas generation and deformation in the Brooks Range fold and thrust belt is provided through petrographic, fluid inclusion, and stable isotope analyses of fracture cements integrated with zircon fission-track data. Predominantly quartz-cemented fractures, collected from thrusted Triassic and Jurassic rocks, contain crack-seal textures, healed microcracks, and curved crystals and fluid inclusion populations, which suggest that cement growth occurred before, during, and after deformation. Fluid inclusion homogenization temperatures (175-250??C) and temperature trends in fracture samples suggest that cements grew at 7-10 km depth during the transition from burial to uplift and during early uplift. CH4-rich (dry gas) inclusions in the Shublik Formation and Kingak Shale are consistent with inclusion entrapment at high thermal maturity for these source rocks. Pressure modeling of these CH4-rich inclusions suggests that pore fluids were overpressured during fracture cementation. Zircon fission-track data in the area record postdeposition denudation associated with early Brooks Range deformation at 64 ?? 3 Ma. With a closure temperature of 225-240??C, the zircon fission-track data overlap homogenization temperatures of coeval aqueous inclusions and inclusions containing dry gas in Kingak and Shublik fracture cements. This critical time-temperature relationship suggests that fracture cementation occurred during early Brooks Range deformation. Dry gas inclusions suggest that Shublik and Kingak source rocks had exceeded peak oil and gas generation temperatures at the time structural traps formed during early Brooks Range deformation. The timing of hydrocarbon generation with respect to deformation therefore represents an important exploration risk for gas exploration in this part of the Brooks Range fold and thrust belt. The persistence of gas high at

  19. Composition of carbonaceous smoke particles from prescribed burning of a Canadian boreal forest: 1. Organic aerosol characterization by gas chromatography

    SciTech Connect

    Mazurek, M.A.; Laterza, C.; Newman, L.; Daum, P.; Cofer, W.R. III; Levine, J.S.; Winstead, E.L.

    1995-06-01

    In this study we examine the molecular organic constituents (C8 to C40 lipid compounds) collected as smoke particles from a Canadian boreal forest prescribed burn. Of special interest are (1) the molecular identity of polar organic aerosols, and (2) the amount of polar organic matter relative to the total mass of aerosol particulate carbon. Organic extracts of smoke aerosol particles show complex distributions of the lipid compounds when analyzed by capillary gas chromatography/mass spectrometry. The molecular constituents present as smoke aerosol are grouped into non-polar (hydrocarbons) and polar {minus}2 oxygen atoms) subtractions. The dominant chemical species found in the boreal forest smoke aerosol are unaltered resin compounds (C20 terpenes) which are abundant in unburned conifer wood, plus thermally altered wood lignins and other polar aromatic hydrocarbons. Our results show that smoke aerosols contain molecular tracers which are related to the biofuel consumed. These smoke tracers can be related structurally back to the consumed softwood and hardwood vegetation. In addition, combustion of boreal forest materials produces smoke aerosol particles that are both oxygen-rich and chemically complex, yielding a carbonaceous aerosol matrix that is enriched in polar substances. As a consequence, emissions of carbonaceous smoke particles from large-scale combustion of boreal forest land may have a disproportionate effect on regional atmospheric chemistry and on cloud microphysical processes.

  20. Opportunities for Gas-Phas Molecular Spectroscopy on the Vls-Pgm Beamline at the Canadian Light Source

    NASA Astrophysics Data System (ADS)

    MacDonald, Michael A.

    2015-06-01

    The VLS-PGM beamline at the Canadian Light Source cover the energy range from 12eV to 250eV with a resolving power better than 104 throughout this range. Associated with this beamline are two endstations designed for gas phase spectroscopy. The first is a dual toroid electrostatic particle energy analyser. Each toroid can (independently) measure the energy and angular distribution of charged particles emitted from the interaction region and can be set for either positive ions or electrons. This allows both photoelectron and ion kinetic energy spectra to be recorded. Recent results from this instrument will be presented including both high resolution photoelectron spectra and photoelectron asymmetry parameter (β) spectra. Coincidence circuitry exists to allow, in favourable circumstances,the measurement of molecular frame photoelectron angular distributions (MFPADs) where the detection of an ion fragment allows orientation of the parent molecule to be deduced. The second is a Wiley-McLaren Time-of-Flight mass spectrometer equipped with multihit electronics. This allows partial ion yield (PIY) spectra to be recorded as well as multi-ion coincidence spectra (PePIPICO). Again recent results will be presented looking at double ionisation in benzene like molecules.

  1. Environmental memory and a possible seasonal bias in the stable isotope composition of (U-Th)/He-dated goethite from the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Yapp, Crayton J.; Shuster, David L.

    2011-08-01

    Goethite (Ax-2) from Axel Heiberg Island (˜80°N) on the margin of the Arctic Ocean is the dominant mineral in a sample of "petrified" Eocene wood, but U, Th, and He measurements suggest that the goethite (α-FeOOH) crystallized in the latest Miocene/Pliocene (ca. 5.5 to 2.8 Ma). Measured δD and δ 18O values of Ax-2 are -221 (±6)‰ and -9.6 (±0.5)‰, respectively. The inferred δD and δ 18O values of the ancient water were about -139‰ and -18.6‰, respectively, with a calculated temperature of crystallization of 3 (±5)°C, which compares with the modern summer (J-J-A) temperature of 3 °C and contrasts with a modern MAT of -19 °C. Published results from various biological proxies on nearby Ellesmere Island indicate a Pliocene (˜4 Ma) MAT of either -6 or -0.4 °C and corresponding seasonal amplitudes of about 18 or 13 °C. A conductive heat flow model suggests that a temperature of 3 °C could represent goethite crystallization at depths of ˜100-200 cm (for MAT = -6 °C) or ˜250-450 cm (for MAT = -0.4 °C) over seasonally restricted intervals of time. The δ 18O value of the Ax-2 water (-18.6‰) is more positive than the modern J-J-A precipitation (-22‰). In combination, the paleotemperatures and δ 18O values of ancient waters (from Ax-2 and published results from three Eocene or Pliocene proxy sites on Axel Heiberg and Ellesmere Islands) are consistent with a warm season bias in those isotopic proxies. The results are also consistent with higher proportions of J-J-A precipitation in the annual total. If so, this emphasizes the importance of seasonality at high latitudes even in times of warmer global climates, and suggests that the Arctic hydrologic cycle, as expressed in the seasonal distribution and isotopic composition of precipitation (perhaps modified by a warmer Arctic Ocean), differed from modern. The δ 13C value of the Fe(CO 3)OH component in the Ax-2 goethite is +6.6‰, which is much more positive than expected if crystallizing

  2. Enantioselective bioaccumulation of hexabromocyclododecane and congener-specific accumulation of brominated diphenyl ethers in an eastern Canadian Arctic marine food web.

    PubMed

    Tomy, Gregg T; Pleskach, Kerri; Oswald, Tyler; Halldorson, Thor; Helm, Paul A; MacInnis, Gordia; Marvin, Chris H

    2008-05-15

    The extent of trophic transfer of the three diastereoisomers of hexabromocyclododecane (HBCD) and seven brominated diphenyl ether (BDE) congeners was examined in components of an Arctic marine food web from eastern Canada. Alpha and gamma-HBCD diastereoisomers were detected in all species and total (sigma) HBCD concentrations ranged from 0.6 +/- 0.2 pg/g (geometric mean +/- 1 x standard error (SE), lipid weight (lw)) in arctic cod to 3.9 +/- 0.9 ng/g (lw) in narwhal. beta-HBCD was below method detection limits in all the samples. Mean sigmaBDE (sum of seven congeners) concentrations ranged from 0.4 +/- 0.2 ng/g (lw) in walrus to 73 +/- 10 ng/g (lw) in zooplankton. The relative trophic status of biota was determined by nitrogen stable isotopes (delta15N), and results indicated clear differences in HBCD isomer and BDE congener profiles with trophic level (TL). Trophic magnification was observed for the alpha-diastereoisomer and BDE-47 as concentrations increased with increasing TL in the food web, whereas there was trophic dilution of gamma-HBCD and BDE-209 through the food web. Only the (-)alpha-enantiomer showed a strong positive relationship between concentration and TL (p < 0.01) with a trophic magnification factor (TMF) value of 2.2. A small but significant increase in the enantiomeric fraction value of the alpha-enantiomers with TL was also observed (r2 = 0.22, p < 0.005), implying that there is an overall preferential enrichment of the (-)alpha-enantiomer relative to the (+)alpha-enantiomer likely due to the greater bioaccumulation potential of the (-)alpha-enantiomer and/or to the greater susceptibility of the (+)alpha-enantiomer to metabolism. PMID:18546701

  3. Assessment of neurotoxic effects of mercury in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) from the Canadian Arctic.

    PubMed

    Krey, Anke; Ostertag, Sonja K; Chan, Hing Man

    2015-03-15

    Marine mammals are indicator species of the Arctic ecosystem and an integral component of the traditional Inuit diet. The potential neurotoxic effects of increased mercury (Hg) in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) are not clear. We assessed the risk of Hg-associated neurotoxicity to these species by comparing their brain Hg concentrations with threshold concentrations for toxic endpoints detected in laboratory animals and field observations: clinical symptoms (>6.75 mg/kg wet weight (ww)), neuropathological signs (>4 mg/kg ww), neurochemical changes (>0.4 mg/kg ww), and neurobehavioral changes (>0.1mg/kg ww). The total Hg (THg) concentrations in the cerebellum and frontal lobe of ringed seals and polar bears were <0.5mg/kg ww, whereas the average concentration in beluga whale brain was >3mg/kg ww. Our results suggest that brain THg levels in polar bears are below levels that induce neurobehavioral effects as reported in the literature, while THg concentrations in ringed seals are within the range that elicit neurobehavioral effects and individual ringed seals exceed the threshold for neurochemical changes. The relatively high THg concentration in beluga whales exceeds all of the neurotoxicity thresholds assessed. High brain selenium (Se):Hg molar ratios were observed in all three species, suggesting that Se could protect the animals from Hg-associated neurotoxicity. This assessment was limited by several factors that influence neurotoxic effects in animals, including: animal species; form of Hg in the brain; and interactions with modifiers of Hg-associated toxicity, such as Se. Comparing brain Hg concentrations in wildlife with concentrations of appropriate laboratory studies can be used as a tool for risk characterization of the neurotoxic effects of Hg in Arctic marine mammals.

  4. Assessment of neurotoxic effects of mercury in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) from the Canadian Arctic.

    PubMed

    Krey, Anke; Ostertag, Sonja K; Chan, Hing Man

    2015-03-15

    Marine mammals are indicator species of the Arctic ecosystem and an integral component of the traditional Inuit diet. The potential neurotoxic effects of increased mercury (Hg) in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) are not clear. We assessed the risk of Hg-associated neurotoxicity to these species by comparing their brain Hg concentrations with threshold concentrations for toxic endpoints detected in laboratory animals and field observations: clinical symptoms (>6.75 mg/kg wet weight (ww)), neuropathological signs (>4 mg/kg ww), neurochemical changes (>0.4 mg/kg ww), and neurobehavioral changes (>0.1mg/kg ww). The total Hg (THg) concentrations in the cerebellum and frontal lobe of ringed seals and polar bears were <0.5mg/kg ww, whereas the average concentration in beluga whale brain was >3mg/kg ww. Our results suggest that brain THg levels in polar bears are below levels that induce neurobehavioral effects as reported in the literature, while THg concentrations in ringed seals are within the range that elicit neurobehavioral effects and individual ringed seals exceed the threshold for neurochemical changes. The relatively high THg concentration in beluga whales exceeds all of the neurotoxicity thresholds assessed. High brain selenium (Se):Hg molar ratios were observed in all three species, suggesting that Se could protect the animals from Hg-associated neurotoxicity. This assessment was limited by several factors that influence neurotoxic effects in animals, including: animal species; form of Hg in the brain; and interactions with modifiers of Hg-associated toxicity, such as Se. Comparing brain Hg concentrations in wildlife with concentrations of appropriate laboratory studies can be used as a tool for risk characterization of the neurotoxic effects of Hg in Arctic marine mammals. PMID:24958011

  5. High Resolution CH4 Emissions and Dissolved CH4 Measurements Elucidate Surface Gas Exchange Processes in Toolik Lake, Arctic Alaska

    NASA Astrophysics Data System (ADS)

    Del Sontro, T.; Sollberger, S.; Kling, G. W.; Shaver, G. R.; Eugster, W.

    2013-12-01

    Approximately 14% of the Alaskan North Slope is covered in lakes of various sizes and depths. Diffusive carbon emissions (CH4 and CO2) from these lakes offset the tundra sink by ~20 %, but the offset would substantially increase if ebullitive CH4 emissions were also considered. Ultimately, arctic lake CH4 emissions are not insignificant in the global CH4 budget and their contribution is bound to increase due to impacts from climate change. Here we present high resolution CH4 emission data as measured via eddy covariance and a Los Gatos gas analyzer during the ice free period from Toolik Lake, a deep (20 m) Arctic lake located on the Alaskan North Slope, over the last few summers. Emissions are relatively low (< 25 mg CH4 m-2 d-1) with little variation over the summer. Diurnal variations regularly occur, however, with up to 3 times higher fluxes at night. Gas exchange is a relatively difficult process to estimate, but is normally done so as the product of the CH4 gradient across the air-water interface and the gas transfer velocity, k. Typically, k is determined based on the turbulence on the water side of the interface, which is most commonly approximated by wind speed; however, it has become increasingly apparent that this assumption does not remain valid across all water bodies. Dissolved CH4 profiles in Toolik revealed a subsurface peak in CH4 at the thermocline of up to 3 times as much CH4 as in the surface water. We hypothesize that convective mixing at night due to cooling surface waters brings the subsurface CH4 to the surface and causes the higher night fluxes. In addition to high resolution flux emission estimates, we also acquired high resolution data for dissolved CH4 in surface waters of Toolik Lake during the last two summers using a CH4 equilibrator system connected to a Los Gatos gas analyzer. Thus, having both the flux and the CH4 gradient across the air-water interface measured directly, we can calculate k and investigate the processes influencing

  6. Numerical investigations of the fluid flows at deep oceanic and arctic permafrost-associated gas hydrate deposits

    NASA Astrophysics Data System (ADS)

    Frederick, Jennifer Mary

    , allows us a unique opportunity to study the response of methane hydrate deposits to warming. Gas hydrate stability in the Arctic and the permeability of the shelf sediments to gas migration is thought to be closely linked with relict submarine permafrost. Submarine permafrost extent depends on several environmental factors, such as the shelf lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, groundwater hydrology, and the salinity of the pore water. Effects of submarine groundwater discharge, which introduces fresh terrestrial groundwater off-shore, can freshen deep marine sediments and is an important control on the freezing point depression of ice and methane hydrate. While several thermal modeling studies suggest the permafrost layer should still be largely intact near-shore, many recent field studies have reported elevated methane levels in Arctic coastal waters. The permafrost layer is thought to create an impermeable barrier to fluid and gas flow, however, talik formation (unfrozen regions within otherwise continuous permafrost) below paleo-river channels can create permeable pathways for gas migration from depth. This is the first study of its kind to make predictions of the methane gas flux to the water column from the Arctic shelf sediments using a 2D multi-phase fluid flow model. Model results show that the dissociation of methane hydrate deposits through taliks can supersaturate the overlying water column at present-day relative to equilibrium with the atmosphere when taliks are large (> 1 km width) or hydrate saturation is high within hydrate layers (> 50% pore volume). Supersaturated waters likely drive a net flux of methane into the atmosphere, a potent greenhouse gas. Effects of anthropogenic global warming will certainly increase gas venting rates if ocean bottom water temperatures increase, but likely won't have immediately observable impacts due to the long response times.

  7. Peat initiation, soil carbon accumulation, fire, and vegetation changes in north-central Canadian arctic lowland forest peatlands during the Holocene

    NASA Astrophysics Data System (ADS)

    Camill, P.; Umbanhowar, C. E., Jr.; Edlund, M. B.; Geiss, C. E.

    2015-12-01

    Peat-forming regions are significant components of the earth system in terms of carbon exchange between the atmosphere and biosphere. While attention has been given to processes controlling carbon accumulation in major peatland/lowland regions at high latitudes, less is known about the processes controlling soil carbon accumulation rates in other globally abundant peat-forming ecosystems, such as lowland arctic forests. These systems are potentially important for two reasons: (1) Many lowland forest peatlands exist at the interface between uplands and aquatic systems; the onset and rate of peat accumulation, as well as the composition of peat mosses, may therefore alter the biogeochemical properties of lakes and streams; (2) soil carbon accumulation might differ from rates observed from the larger open peatlands, offering additional insights to the vulnerability of high-latitude peat to climatic change. We collected and dated 25 peat cores from eight lake sites in an 18,000-km2 low-arctic region of Manitoba Canada and measured areal carbon accumulation rates, charcoal concentration (as a proxy for fire severity), and plant macrofossils (as a proxy for vegetation change). The distribution of basal radiocarbon dates indicates that the oldest peat initiation occurred 7,000-8,000 B.P. in post-glacial landscapes, but peak peat formation occurred < 3,000 B.P., presumably as landscape paludification rose with increased net moisture during Neoglacial cooling. In locations where peat initiation occurred before 6,000 B.P., the initial communities were variable (bog-poor fen-moderate rich fen), whereas most sites initiating after 6,000 B.P. formed (and remained) as bogs, suggesting increasing dominance of Sphagnum peatmosses as paludification progressed. Carbon accumulation rates were consistently low (10-30 gm-2y-1), with no clear correlation to fire. Also absent was rapid accumulation early in the peatland development characteristic of early successional fens. These results

  8. Potential oil and gas resources of the Arctic National Wildlife Refuge in Alaska: 1002 area

    USGS Publications Warehouse

    Bird, K.J.

    2000-01-01

    A geologist with extensive experience in the study of northern Alaska's petroleum resources provides an overview of the first comprehensive reassessment of the petroleum potential of section 1002 of the Arctic National Wildlife Refuge since the original study of 1987. The paper surveys the region's geology, and provides a description of the methods employed and assessment results. The current resource is compared with that estimated in the original study, and is considerably larger, given the availability of new geologic and geophysical data, improved seismic processing and interpretation capabilities, and changes in the economics of North Slope oil development.

  9. The gas/particle partitioning of polycyclic aromatic hydrocarbons collected at a sub-Arctic site in Canada

    NASA Astrophysics Data System (ADS)

    Sofowote, Uwayemi M.; Hung, Hayley; Rastogi, Ankit K.; Westgate, John N.; Su, Yushan; Sverko, Ed; D'Sa, Ivy; Roach, Pat; Fellin, Phil; McCarry, Brian E.

    2010-12-01

    Polycyclic aromatic hydrocarbons (PAH) were measured in air samples at a remote air monitoring site established in the Yukon Territory, Canada as part of a global project (International Polar Year; IPY) to study the potential for atmospheric long-range transport of anthropogenic pollutants to the Arctic. Gas- and particle-phase PAH were collected in polyurethane foam plugs and on glass fibre filters respectively from August 2007 to October 2009. PAH concentrations were found to be highest in the winter months and lowest in summer. The gas/particle partitioning coefficients of 3-5 ringed PAH were computed and seasonal averages were compared. In the summer time, lower molecular mass PAH exhibited relatively higher partitioning into the particle-phase. This particle-phase partitioning led to the shallowest slopes being recorded during summer for the log-log correlation plots between the PAH partition coefficients and their sub-cooled vapour pressures. Air mass back trajectories suggest that local impacts may be more important during the summer time which is marked by increased camping activities at camping sites in the proximity of the sampling station. In conclusion, both summer and wintertime variations in PAH concentrations and gas/particle partitioning are considered to be source- and phototransformation-dependent rather than dependent on temperature-driven shifts in equilibrium partitioning.

  10. Development and Demonstration of Mobile, Small Footprint Exploration and Development Well System for Arctic Unconventional Gas Resources (ARCGAS)

    SciTech Connect

    Paul Glavinovich

    2002-11-01

    Traditionally, oil and gas field technology development in Alaska has focused on the high-cost, high-productivity oil and gas fields of the North Slope and Cook Inlet, with little or no attention given to Alaska's numerous shallow, unconventional gas reservoirs (carbonaceous shales, coalbeds, tight gas sands). This is because the high costs associated with utilizing the existing conventional oil and gas infrastructure, combined with the typical remoteness and environmental sensitivity of many of Alaska's unconventional gas plays, renders the cost of exploring for and producing unconventional gas resources prohibitive. To address these operational challenges and promote the development of Alaska's large unconventional gas resource base, new low-cost methods of obtaining critical reservoir parameters prior to drilling and completing more costly production wells are required. Encouragingly, low-cost coring, logging, and in-situ testing technologies have already been developed by the hard rock mining industry in Alaska and worldwide, where an extensive service industry employs highly portable diamond-drilling rigs. From 1998 to 2000, Teck Cominco Alaska employed some of these technologies at their Red Dog Mine site in an effort to quantify a large unconventional gas resource in the vicinity of the mine. However, some of the methods employed were not fully developed and required additional refinement in order to be used in a cost effective manner for rural arctic exploration. In an effort to offset the high cost of developing a new, low-cost exploration methods, the US Department of Energy, National Petroleum Technology Office (DOE-NPTO), partnered with the Nana Regional Corporation and Teck Cominco on a technology development program beginning in 2001. Under this DOE-NPTO project, a team comprised of the NANA Regional Corporation (NANA), Teck Cominco Alaska and Advanced Resources International, Inc. (ARI) have been able to adapt drilling technology developed for the

  11. Impact of the Healthy Foods North nutrition intervention program on Inuit and Inuvialuit food consumption and preparation methods in Canadian Arctic communities

    PubMed Central

    2014-01-01

    Background The 12-month Healthy Foods North intervention program was developed to improve diet among Inuit and Inuvialuit living in Arctic Canada and assess the impact of the intervention established for the communities. Methods A quasi-experimental study randomly selected men and women (≥19 years of age) in six remote communities in Nunavut and the Northwest Territories. Validated quantitative food frequency and adult impact questionnaires were used. Four communities received the intervention and two communities served as delayed intervention controls. Pre- and post-intervention changes in frequency of/total intake of de-promoted food groups and healthiness of cooking methods were determined. The impact of the intervention was assessed using analysis of covariance (ANCOVA). Results Post-intervention data were analysed in the intervention (n = 221) and control (n = 111) communities, with participant retention rates of 91% for Nunavut and 83% for the Northwest Territories. There was a significant decrease in de-promoted foods, such as high fat meats (−27.9 g) and high fat dairy products (−19.8 g) among intervention communities (all p ≤ 0.05). The use of healthier preparation methods significantly increased (14.7%) in intervention communities relative to control communities. Conclusions This study highlights the importance of using a community-based, multi-institutional nutrition intervention program to decrease the consumption of unhealthy foods and the use of unhealthy food preparation methods. PMID:24993180

  12. a New Japanese Project for Arctic Climate Change Research - Grene Arctic - (Invited)

    NASA Astrophysics Data System (ADS)

    Enomoto, H.

    2013-12-01

    A new Arctic Climate Change Research Project 'Rapid Change of the Arctic Climate System and its Global Influences' has started in 2011 for a five years project. GRENE-Arctic project is an initiative of Arctic study by more than 30 Japanese universities and institutes as the flame work of GRENE (Green Network of Excellence) of MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan). The GRENE-Arctic project set four strategic research targets: 1. Understanding the mechanism of warming amplification in the Arctic 2. Understanding the Arctic system for global climate and future change 3. Evaluation of the effects of Arctic change on weather in Japan, marine ecosystems and fisheries 4. Prediction of sea Ice distribution and Arctic sea routes This project aims to realize the strategic research targets by executing following studies: -Improvement of coupled general circulation models based on validations of the Arctic climate reproducibility and on mechanism analyses of the Arctic climate change and variability -The role of Arctic cryosphere in the global change -Change in terrestrial ecosystem of pan-Arctic and its effect on climate -Studies on greenhouse gas cycles in the Arctic and their responses to climate change -Atmospheric studies on Arctic change and its global impacts -Ecosystem studies of the Arctic ocean declining Sea ice -Projection of Arctic Sea ice responding to availability of Arctic sea route (* ** ***) *Changes in the Arctic ocean and mechanisms on catastrophic reduction of Arctic sea ice cover **Coordinated observational and modeling studies on the basic structure and variability of the Arctic sea ice-ocean system ***Sea ice prediction and construction of ice navigation support system for the Arctic sea route. Although GRENE Arctic project aims to product scientific contribution in a concentrated program during 2011-2016, Japanese Arctic research community established Japan Consortium for Arctic Environmental Research (JCAR) in May

  13. Methanotrophic activity in the water column above shallow gas flares west of Prins Karls Forland, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gründger, Friederike; Svenning, Mette M.; Niemann, Helge; Silyakova, Anna; Serov, Pavel; Pavlov, Alexey K.; Granskog, Mats A.; Ferre, Bénédicte; Carroll, JoLynn

    2016-04-01

    Numerous gas flares, interpreted to be streams of methane bubbles, were discovered in shallow waters (average water depth about 90 m) on the continental shelf west of Prins Karls Forland (Western Svalbard) in the Arctic Ocean. Gas is released from the seabed to the water column and potentially transferred into the atmosphere where it acts as a potent greenhouse gas. In order to resolve the fate of dissolved methane in the water column, we carried out grid-pattern biogeochemical measurements in the study area of 30 x 15 km. Specifically, we measured concentrations of dissolved methane and microbial methane oxidation (MOx) rates at 8 water depths at 31 sampling stations and performed 16S rRNA sequencing analysis on selected samples to characterize the microbial community composition. Availability of dissolved methane is essential for the process of microbial methane oxidation. However, our measurements reveal that high concentrations of dissolved methane in the water column do not necessarily lead to high MOx rates. Our results indicated that the presence of marine methanotrophic biomass as well as dissolved organic matter is of larger importance for the process of microbial methane oxidation. For example, we found MOx hot spots with values up to 13 nmol l‑1 d‑1 at bottom water depth with dissolved methane concentrations less than 160 nmol l‑1. In contrast, at stations where bottom methane concentration values reached 640 nmol l‑1, MOx rates were less than 0.7 nmol l‑1 d‑1. To interpret observed interconnection between methane concentrations and MOx rates, we use vertical distributions of seawater temperature, salinity and properties of colored dissolved organic matter (CDOM). This information helps us characterize the oceanographic setting and circulation patterns in the area, which we believe has a major impact on the origin and distribution of methanotrophic microbial biomass and methane oxidation in methanerich bottom water. This study is part of the

  14. Methanotrophic activity in the water column above shallow gas flares west of Prins Karls Forland, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gründger, Friederike; Svenning, Mette M.; Niemann, Helge; Silyakova, Anna; Serov, Pavel; Pavlov, Alexey K.; Granskog, Mats A.; Ferre, Bénédicte; Carroll, JoLynn

    2016-04-01

    Numerous gas flares, interpreted to be streams of methane bubbles, were discovered in shallow waters (average water depth about 90 m) on the continental shelf west of Prins Karls Forland (Western Svalbard) in the Arctic Ocean. Gas is released from the seabed to the water column and potentially transferred into the atmosphere where it acts as a potent greenhouse gas. In order to resolve the fate of dissolved methane in the water column, we carried out grid-pattern biogeochemical measurements in the study area of 30 x 15 km. Specifically, we measured concentrations of dissolved methane and microbial methane oxidation (MOx) rates at 8 water depths at 31 sampling stations and performed 16S rRNA sequencing analysis on selected samples to characterize the microbial community composition. Availability of dissolved methane is essential for the process of microbial methane oxidation. However, our measurements reveal that high concentrations of dissolved methane in the water column do not necessarily lead to high MOx rates. Our results indicated that the presence of marine methanotrophic biomass as well as dissolved organic matter is of larger importance for the process of microbial methane oxidation. For example, we found MOx hot spots with values up to 13 nmol l-1 d-1 at bottom water depth with dissolved methane concentrations less than 160 nmol l-1. In contrast, at stations where bottom methane concentration values reached 640 nmol l-1, MOx rates were less than 0.7 nmol l-1 d-1. To interpret observed interconnection between methane concentrations and MOx rates, we use vertical distributions of seawater temperature, salinity and properties of colored dissolved organic matter (CDOM). This information helps us characterize the oceanographic setting and circulation patterns in the area, which we believe has a major impact on the origin and distribution of methanotrophic microbial biomass and methane oxidation in methanerich bottom water. This study is part of the Centre for

  15. Temperature effects on net greenhouse gas production and bacterial communities in arctic thaw ponds.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Lovejoy, Connie

    2016-08-01

    One consequence of High Arctic permafrost thawing is the formation of small ponds, which release greenhouse gases (GHG) from stored carbon through microbial activity. Under a climate with higher summer air temperatures and longer ice-free seasons, sediments of shallow ponds are likely to become warmer, which could influence enzyme kinetics or select for less cryophilic microbes. There is little data on the direct temperature effects on GHG production and consumption or on microbial communities' composition in Arctic ponds. We investigated GHG production over 16 days at 4°C and 9°C in sediments collected from four thaw ponds. Consistent with an enzymatic response, production rates of CO2 and CH4 were significantly greater at higher temperatures, with Q10 varying from 1.2 to 2.5. The bacterial community composition from one pond was followed through the incubation by targeting the V6-V8 variable regions of the 16S rRNA gene and 16S rRNA. Several rare taxa detected from rRNA accounted for significant community compositional changes. At the higher temperature, the relative community contribution from Bacteroidetes decreased by 15% with compensating increases in Betaproteobacteria, Alphaproteobacteria, Firmicutes, Acidobacteria, Verrucomicrobia and Actinobacteria. The increase in experimental GHG production accompanied by changes in community indicates an additional factor to consider in sediment environments when evaluating future climate scenarios. PMID:27288196

  16. Well-to-Wheels Greenhouse Gas Emissions of Canadian Oil Sands Products: Implications for U.S. Petroleum Fuels.

    PubMed

    Cai, Hao; Brandt, Adam R; Yeh, Sonia; Englander, Jacob G; Han, Jeongwoo; Elgowainy, Amgad; Wang, Michael Q

    2015-07-01

    Greenhouse gas (GHG) regulations affecting U.S. transportation fuels require holistic examination of the life-cycle emissions of U.S. petroleum feedstocks. With an expanded system boundary that included land disturbance-induced GHG emissions, we estimated well-to-wheels (WTW) GHG emissions of U.S. production of gasoline and diesel sourced from Canadian oil sands. Our analysis was based on detailed characterization of the energy intensities of 27 oil sands projects, representing industrial practices and technological advances since 2008. Four major oil sands production pathways were examined, including bitumen and synthetic crude oil (SCO) from both surface mining and in situ projects. Pathway-average GHG emissions from oil sands extraction, separation, and upgrading ranged from ∼6.1 to ∼27.3 g CO2 equivalents per megajoule (in lower heating value, CO2e/MJ). This range can be compared to ∼4.4 g CO2e/MJ for U.S. conventional crude oil recovery. Depending on the extraction technology and product type output of oil sands projects, the WTW GHG emissions for gasoline and diesel produced from bitumen and SCO in U.S. refineries were in the range of 100-115 and 99-117 g CO2e/MJ, respectively, representing, on average, about 18% and 21% higher emissions than those derived from U.S. conventional crudes. WTW GHG emissions of gasoline and diesel derived from diluted bitumen ranged from 97 to 103 and 96 to 104 g CO2e/MJ, respectively, showing the effect of diluent use on fuel emissions.

  17. Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores.

    PubMed

    Stern, G A; Braekevelt, E; Helm, P A; Bidleman, T F; Outridge, P M; Lockhart, W L; McNeeley, R; Rosenberg, B; Ikonomou, M G; Hamilton, P; Tomy, G T; Wilkinson, P

    2005-04-15

    Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production. The lower than expected HOC concentrations in older sediment slices may be due to anaerobic degradation and possibly to dilution resulting from a temporary increase in sedimentation rate observed between the mid-1960s and 1970s. Indeed, temporal trends were more readily apparent for those compound classes when anaerobic metabolites were also analyzed, such as for DDT and toxaphene. However, it is postulated here for the first time that the maximum or increasing HOC surface fluxes observed for many of the major compound classes in DV09 sediments may be influenced by climate variation and the resulting increase in algal primary productivity which could drive an increasing rate of HOC scavenging from the water column. Both the fraction (F(TC)) and enantiomer fraction (EF) of trans-chlordane (TC) decreased significantly between 1957 and 1997, suggesting that recent inputs to the lake are from weathered chlordane sources. PCDD/Fs showed a change in sources from pentachlorophenol (PeCP) in the 1950s and 1960s to combustion sources into the 1990s. Improvements in combustion technology may be responsible for the reducing the proportion of TCDF relative to OCDD in the most recent slice.

  18. Canadian History.

    ERIC Educational Resources Information Center

    School Libraries in Canada, 2003

    2003-01-01

    Includes 22 articles that address Canadian history and the importance of having students honor Canada's past by providing articles relating to the areas of History and Social Studies covering: historical fiction as instructional material; Canadian scientists; agricultural fairs; the Historical Foundation; social science books on Canada; student…

  19. FORMATION OF REACTIVE GASEOUS MERCURY IN THE ARCTIC: EVIDENCE OF OXIDATION OF HG0 TO GAS-PHASE HG-II COMPOUNDS AFTER ARCTIC SUNRISE

    EPA Science Inventory

    We have measured total gaseous mercury concentrations (Hgo) at Point Barrow, Alaska since September 1998 in an effort to determine the geographic extent and reaction mechanism of the so-called mercury depletion events (MDE) previously reported in the high Arctic at Alert, Canad...

  20. Sudden changes in aerosol and gas concentrations in the central Arctic marine boundary layer: Causes and consequences

    NASA Astrophysics Data System (ADS)

    Bigg, E. Keith; Leck, Caroline; Nilsson, E. Douglas

    2001-12-01

    Measurements of aerosol number size distributions and concentrations of the precursor gases dimethyl sulfide, sulfur dioxide and ammonia were made within the pack ice region of the central Arctic Ocean during July and August 1996 from the icebreaker Oden. Changes in concentration, sometimes exceeding the entire seasonal variation, often occurred within an hour and attempts to find the reasons for them are described. Vertical profiles of aerosol concentration in Aitken and accumulation mode particles obtained on helicopter flights revealed intense concentration gradients in the lowest 1000 m. Those below 100 m were common. Concentrations of accumulation mode particles were usually greater near the surface than at 100 m. Four representative case studies for which vertical aerosol profiles were obtained are presented. Observations of rapid large changes in near-surface concentration of aerosols in different size ranges are compared with the vertical profiles, meteorological information, and acoustic or optical remote sensing to infer processes causing the changes. Comparison of simultaneous variations in aerosols and precursor gas concentrations are used to define the vertical profiles of the gases. It was found that dimethyl sulfide and ammonia concentrations usually must have been strongly depleted near the surface relative to concentrations at about 100 m. Sulfur dioxide profiles appeared to be more complex. Turbulence or vertical air motions initiated by atmospheric wave motions trapped within the stable boundary layer appeared to be directly responsible for many of the sudden concentration changes, through interaction with concentration gradients close to the surface. The presence of low-level jets also had direct or indirect influences on mixing in the lowest few hundred meters. The extent to which aerosols measured near the surface can determine the microphysics of central Arctic marine boundary layer clouds is examined.

  1. The role of declining Arctic sea ice in recent decreasing terrestrial Arctic snow depths

    NASA Astrophysics Data System (ADS)

    Park, Hotaek; Walsh, John E.; Kim, Yongwon; Nakai, Taro; Ohata, Tetsuo

    2013-06-01

    The dramatic decline in Arctic sea ice cover is anticipated to influence atmospheric temperatures and circulation patterns. These changes will affect the terrestrial climate beyond the boundary of the Arctic, consequently modulating terrestrial snow cover. Therefore, an improved understanding of the relationship between Arctic sea ice and snow depth over the terrestrial Arctic is warranted. We examined responses of snow depth to the declining Arctic sea ice extent in September, during the period of 1979-2006. The major reason for a focus on snow depth, rather than snow cover, is because its variability has a climatic memory that impacts hydrothermal processes during the following summer season. Analyses of combined data sets of satellite measurements of sea ice extent and snow depth, simulated by a land surface model (CHANGE), suggested that an anomalously larger snow depth over northeastern Siberia during autumn and winter was significantly correlated to the declining September Arctic sea ice extent, which has resulted in cooling temperatures, along with an increase in precipitation. Meanwhile, the reduction of Arctic sea ice has amplified warming temperatures in North America, which has readily offset the input of precipitation to snow cover, consequently further decreasing snow depth. However, a part of the Canadian Arctic recorded an increase in snow depth driven locally by the diminishing September Arctic sea ice extent. Decreasing snow depth at the hemispheric scale, outside the northernmost regions (i.e., northeastern Siberia and Canadian Arctic), indicated that Arctic amplification related to the diminishing Arctic sea ice has already impacted the terrestrial Arctic snow depth. The strong reduction in Arctic sea ice anticipated in the future also suggests a potential long-range impact on Arctic snow cover. Moreover, the snow depth during the early snow season tends to contribute to the warming of soil temperatures in the following summer, at least in the

  2. Impact of declining Arctic sea ice on recent decreasing terrestrial Arctic snow depths

    NASA Astrophysics Data System (ADS)

    PARK, H.; Walsh, J. E.; Kim, Y.; Nakai, T.; Ohata, T.

    2012-12-01

    The dramatic decline in Arctic sea ice cover is anticipated to influence atmospheric temperatures and circulation patterns. These changes will affect the terrestrial climate beyond the boundary of the Arctic, consequently modulating terrestrial snow cover. Therefore, an improved understanding of the relationship between Arctic sea ice and snow depth over the terrestrial Arctic is warranted. We examined responses of snow depth to the declining Arctic sea ice extent in September, during the period of 1979-2006. The major reason for a focus on snow depth, rather than snow cover, is because its variability has a climatic memory that impacts hydrothermal processes during the following summer season. Analyses of combined data sets of satellite measurements of sea ice extent and snow depth, simulated by a land surface model (CHANGE), suggested that an anomalously larger snow depth over northeastern Siberia during autumn and winter was significantly correlated to the declining September Arctic sea ice extent, which has resulted in cooling temperatures, along with an increase in precipitation. Meanwhile, the reduction of Arctic sea ice has amplified warming temperatures in North America, which has readily offset the input of precipitation to snow cover, consequently further decreasing snow depth. However, a part of the Canadian Arctic recorded an increase in snow depth driven locally by the diminishing September Arctic sea ice extent. Decreasing snow depth at the hemispheric scale, outside the northernmost regions (i.e., northeastern Siberia and Canadian Arctic), indicated that Arctic amplification related to the diminishing Arctic sea ice has already impacted the terrestrial Arctic snow depth. The strong reduction in Arctic sea ice anticipated in the future also suggests a potential long-range impact on Arctic snow cover. Moreover, the snow depth during the early snow season tends to contribute to the warming of soil temperatures in the following summer, at least in the

  3. Report of the workshop on Arctic oil and gas recovery held at Sandia National Laboratories, Albuquerque, New Mexico, June 30-July 2, 1980

    SciTech Connect

    Sackinger, W. M.

    1980-09-01

    This report is the result of a workshop on Arctic offshore oil and gas recovery, held at Sandia National Laboratories Albuquerque, New Mexico, on June 30-July 2, 1980. Research priorities for the technology related to Arctic offshore oil and gas production were defined. The workshop was preceded by a report entitled, A Review of Technology for Arctic Offshore Oil and Gas Recovery, authored by Dr. W. M. Sackinger. The mission of the workshop was to identify research priorities without considering whether the research should be conducted by government or by industry. Nevertheless, at the end of the meeting the general discussion did consider this, and the concensus was that environmental properties should certainly be of concern to the government, that implementation of petroleum operations was the province of industry, and that overlapping, coordinated areas of interest include both environment and interactions of the environment with structures, transport systems, and operations. An attempt to establish relative importance and a time frame was made after the workshop through the use of a survey form. The form and a summary of its results, and a discussion of its implications, are given.

  4. New Evidence of the Existence of Gas Migration Pathways Through Sub-Sea Permafrost in the East Siberian Arctic Shelf

    NASA Astrophysics Data System (ADS)

    Shakhova, N. E.; Semiletov, I. P.; Salomatin, A.; Yusupov, V.; Lobkovsky, L.; Dmitrievsky, N.; Karnaukh, V.; Kosmach, D.; Chernikh, D.; Anan'ev, R.

    2012-12-01

    To assess whether sudden, large-scale releases are taking place in the East Siberian Arctic Shelf (ESAS) or are likely to occur in the future we investigated the migration pathway characteristics and identified controlling factors of methane (CH4) flux from the seabed, through the water column, and into the atmosphere. Evidence of the existence of migration pathways through permafrost is provided by seismic data, specifically as low-amplitude anomalies sometimes referred to as washed-out or semi-blanked zones. In the marine environment, widespread washed-out zones often have been attributed to gas hydrates. In permafrost, low seismic amplitude may also result from variations of physical properties or property changes associated with development of deep taliks. The most prominent features of the seafloor morphology associated with the bubble releases observed in the mid-outer shelf (water depth >30 m) were morphological features that could be attributed to gas release from permeable/unconsolidated sediments: pockmarks (PMs), PM-induced erosion channels, collapse depression, and features related to mass wasting and sub-marine sediment slides. Acoustic anomalies observed in high-resolution seismic images obtained in mid-outer shelf reflect large volumes of free gas ascending within highly permeable sediments, so-called "gas curtains" and "gas blankets". Where such acoustic anomalies were observed, we detected very high concentrations of bubble seeps, which appeared not as single bubble streams (i.e. individual bubbles released continuously) that were mostly observed in the inner part of the ESAS, but as columns of bubbles (termed flares) rising to the sea surface. One of the most prominent morphological features observed in the ESAS (water depth <90 m) was associated with temporal gas releases was caused by ice scouring. The effect of this scouring is the creation of a long linear furrow that follows a relatively straight line and extends from only a few tens of

  5. Modeling the evolution of climate-sensitive Arctic subsea permafrost in regions of extensive gas expulsion at the West Yamal shelf

    NASA Astrophysics Data System (ADS)

    Portnov, Alexey; Mienert, Jurgen; Serov, Pavel

    2014-11-01

    Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Expulsions of methane from shallow Russian Arctic shelf areas may continue to rise in response to intense degradation of relict subsea permafrost. Here we show modeling of the permafrost evolution from the Late Pleistocene to present time at the West Yamal shelf. Modeling results suggest a highly dynamic permafrost system that directly responds to even minor variations of lower and upper boundary conditions, e.g., geothermal heat flux from below and/or bottom water temperature changes from above permafrost. Scenarios of permafrost evolution show a potentially nearest landward modern extent of the permafrost at the West Yamal shelf limited by ~17 m isobaths, whereas its farthest seaward extent coincides with ~100 m isobaths. The model also predicts seaward tapering of relict permafrost with a maximal thickness of 275-390 m near the shoreline. Previous field observations detected extensive emissions of free gas into the water column at the transition zone between today's shallow water permafrost (<20 m) and deeper water nonpermafrost areas (>20 m). The model adapts well to corresponding heat flux and ocean temperature data, providing crucial information about the modern permafrost conditions. It shows current locations of upper and lower permafrost boundaries and evidences for possible release of methane from the seabed to the hydrosphere in a warming Arctic.

  6. Active mud volcanoes on the continental slope of the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Caress, D. W.; Gwiazda, R.; Melling, H.; Riedel, M.; Jin, Y. K.; Hong, J. K.; Kim, Y.-G.; Graves, D.; Sherman, A.; Lundsten, E.; Anderson, K.; Lundsten, L.; Villinger, H.; Kopf, A.; Johnson, S. B.; Hughes Clarke, J.; Blasco, S.; Conway, K.; Neelands, P.; Thomas, H.; Côté, M.

    2015-09-01

    Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.

  7. Characterization and profiling of hepatic cytochromes P450 and phase II xenobiotic-metabolizing enzymes in beluga whales (Delphinapterus leucas) from the St. Lawrence River Estuary and the Canadian Arctic.

    PubMed

    McKinney, Melissa A; Arukwe, Augustine; De Guise, Sylvain; Martineau, Daniel; Béland, Pierre; Dallaire, André; Lair, Stéphane; Lebeuf, Michel; Letcher, Robert J

    2004-07-30

    Cytochromes P450 (CYP, phase I) and conjugating (phase II) enzymes can be induced by and influence the toxicokinetics (metabolism) and toxicity of xenobiotic contaminants in exposed organisms. Beluga whale (Delphinapterus leucas) from the endangered St. Lawrence (SL) River Estuary population exhibit deleterious health effects and various severe pathologies that have been associated with contaminant exposure. In contrast, such effects (e.g. reproductive and immunological impairment) are generally less frequent in less exposed populations in the Canadian Arctic (CA). In the present study, opportunistic sampling resulted in the collection immediately after death of liver ti