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Sample records for arctic sediments implies

  1. Late to middle Pleistocene Arctic glacial history implied from a sedimentary record from the Northwind Ridge

    Science.gov (United States)

    Liu, Y.; Dong, L.; Shi, X.; Zhu, A.

    2017-12-01

    Abstract: Sediment core ARC6-C21 collected from the Northwind Ridge, western Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stages (MIS) 1-11), as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of the elemental composition of sediment along with grain size in core ARC6-C21 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from geochemical composition. Notably, peaks of MgO and CaO, including large dropstones, presumably track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) and/or Eurasia Ice Sheet (EIS)are inferred from peaks of SiO2, K2O and Na2O associated with coarse sediment. Major ESIS and/or EIS sedimentary events occurred in the intervals estimated as MIS 2, MIS 4, MIS 6, MIS 8 and MIS 10. Keywords: Sediment core, Pleistocene, western Arctic Ocean, geochemistry, grain size, sediment provenance, glaciations

  2. Anthropogenic mercury deposition to arctic lake sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hermanson, M.H. [Westchester University, Westchester, PA (United States). Dept. of Health

    1998-01-01

    The history of atmospheric mercury inputs to remote arctic regions can be measured in lake sediment cores using lead-210 chronology. In the investigation, total mercury deposition is measured in sediments from Imitavik and Annak Lakes on the Belcher Islands in southeastern Hudson Bay, an area in the southern Canadian Arctic with no history of local industrial or agricultural sources of contamination. Both lakes received background and atmospheric inputs of mercury while Annak also received mercury from raw domestic sewage from the Hamlet of Sanikiluaq, a growing Inuit community of about 550 established in the late 1960s. Results from Imitavik show that anthropogenic mercury inputs, apparently transported through the atmosphere, began to appear in the mid-eighteenth century, and continued to the 1990s. Annak had a similar mercury history until the late 1960s when disposal of domestic sewage led to increased sediment and contaminant accumulation. The high input of mercury to Annak confirms that Sanikiluaq residents are exposed to mercury through native food sources. 39 refs., 7 figs., 3 tabs.

  3. Submarine landslides in Arctic sedimentation: Canada Basin

    Science.gov (United States)

    Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Lebedova-Ivanova, N; Chapman, C.

    2016-01-01

    Canada Basin of the Arctic Ocean is the least studied ocean basin in the World. Marine seismic field programs were conducted over the past 6 years using Canadian and American icebreakers. These expeditions acquired more than 14,000 line-km of multibeam bathymetric and multi-channel seismic reflection data over abyssal plain, continental rise and slope regions of Canada Basin; areas where little or no seismic reflection data existed previously. Canada Basin is a turbidite-filled basin with flat-lying reflections correlateable over 100s of km. For the upper half of the sedimentary succession, evidence of sedimentary processes other than turbidity current deposition is rare. The Canadian Archipelago and Beaufort Sea margins host stacked mass transport deposits from which many of these turbidites appear to derive. The stratigraphic succession of the MacKenzie River fan is dominated by mass transport deposits; one such complex is in excess of 132,000 km2 in area and underlies much of the southern abyssal plain. The modern seafloor is also scarred with escarpments and mass failure deposits; evidence that submarine landsliding is an ongoing process. In its latest phase of development, Canada Basin is geomorphologically confined with stable oceanographic structure, resulting in restricted depositional/reworking processes. The sedimentary record, therefore, underscores the significance of mass-transport processes in providing sediments to oceanic abyssal plains as few other basins are able to do.

  4. Mobilization of radionuclides from sediments. Potential sources to Arctic waters

    International Nuclear Information System (INIS)

    Oughton, D.H.; Boerretzen, P.; Mathisen, B.; Salbu, B.; Tronstad, E.

    1995-01-01

    Contaminated soils and sediments can act as secondary sources of radionuclides to Arctic waters. In cases where the original source of contamination has ceased or been greatly reduced (e.g., weapons' testing, waste discharges from Mayak and Sellafield) remobilization of radionuclides from preciously contaminated sediments increases in importance. With respect to Arctic waters, potential secondary sources include sediments contaminated by weapons' testing, by discharges from nuclear installations to seawater, e.g., the Irish Sea, or by leakages from dumped waste containers. The major land-based source is run-off from soils and transport from sediments in the catchment areas of the Ob and Yenisey rivers, including those contaminated by Mayak discharges. Remobilization of radionuclides is often described as a secondary source of contamination. Whereas primary sources of man-made radionuclides tend to be point sources, secondary sources are usually more diffuse. Experiments were carried out on marine (Kara Sea, Irish Sea, Stepovogo and Abrosimov Fjords), estuarine (Ob-Yenisey) and dirty ice sediments. Total 137 Cs and 90 Sr concentrations were determined using standard radiochemical techniques. Tracer studies using 134 Cs and 85 Sr were used to investigate the kinetics of radionuclide adsorption and desorption. It is concluded that 90 Sr is much less strongly bound to marine sediments than 137 Cs, and can be chemically mobilized through ion exchange with elements is seawater. Radiocaesium is strongly and rapidly fixed to sediments. Discharges of 137 Cs to surface sediments (i.e., from dumped containers) would be expected to be retained in sediments to a greater extent than discharges to sea-waters. Physical mobilization of sediments, for example resuspension, may be of more importance for transport of 137 Cs than for 90 Sr. 7 refs., 4 figs

  5. Chemical composition of sediments from White Sea, Russian Arctic

    Science.gov (United States)

    Gamza, Olga; Shevchenko, Vladimir; Novigatsky, Aleksandr

    2010-05-01

    The White Sea, the only Russian inland sea, is located on the north of outlying districts of the European part of Russia, belongs to Arctic Ocean. Area of water of sea occupies about 90 tousend square kilometers. The sea can be divided into some general parts: neck, funnel, basin and 4 Bays: Dvina Bay, Kandalaksha Bay, Mezen Bay and Onega Bay. The purpose of this work was geochemical mapping of the surface sediments of this area. The main tasks were: compilation data base of element composition of the surface sediments, geochemical mapping of each element, research of the anormal concentration of elements on the surface. To detect the content of chemical elements several methods were used: atomic absorption spectrometry (P.P. Shirshov Institute of Oceanology); neutron activation analysis (Vernadsky Institute of Geochemistry and Analytical Chemistry), total and organic carbon analysis, photometric method to detection Si, Al, P (P.P. Shirshov Institute of Oceanology). Bulk composition is one of the fundamental characteristics of sediments and bottom deposites of modern basins. Coarse-grained sediments with portion of pelitic component 80%). Character of elements distribution correlates with facial distribution of sediments from White Sea. According to litologic description, bottom surface of Dvina Bay is practically everywhere covered by layer of fine-grained sand. In the border area between Dvina Bay and White Sea basin on terraced subwater slope aleurite politic silts are abundant. They tend to exhange down the slope to clay silts. In Onega Bay fractions of non-deposition are observed. They are characterized by wide spread of thin blanket poorgraded sediments, which are likely to be relic. Relief of Kandalakscha Bay bottom is presented as alternation of abyssal fosses (near 300 m) with silles and elevations (roof owning to diagenetic contraction. Authors thank academic Lisitsyn for encourage, Andrey Apletalin for valuable help, and everybody, who helped in field

  6. Sediments in Arctic sea ice: Implications for entrainment, transport and release

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    Nurnberg, D.; Wollenburg, I.; Dethleff, D.; Eicken, H.; Kassens, H.; Letzig, T.; Reimnitz, E.; Thiede, Jorn

    1994-01-01

    Despite the Arctic sea ice cover's recognized sensitivity to environmental change, the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood. Sea ice sediment inclusions were studied in the central Arctic Ocean during the Arctic 91 expedition and in the Laptev Sea (East Siberian Arctic Region Expedition 1992). Results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central Arctic Ocean. This study documents the regional distribution and composition of particle-laden ice, investigates and evaluates processes by which sediment is incorporated into the ice cover, and identifies transport paths and probable depositional centers for the released sediment. In April 1992, sea ice in the Laptev Sea was relatively clean. The sediment occasionally observed was distributed diffusely over the entire ice column, forming turbid ice. Observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment. In the central Arctic Ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes. The surface sediment accumulation in central Arctic multi-year sea ice exceeds by far the amounts observed in first-year ice from the Laptev Sea in April 1992. Sea ice sediments are generally fine grained, although coarse sediments and stones up to 5 cm in diameter are observed. Component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles. The biogenous components, namely shells of pelecypods and benthic foraminiferal tests, point to a shallow, benthic, marine source area. Apparently, sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing. Clay mineralogy of ice-rafted sediments provides information on potential source areas. A smectite

  7. Bacterial biogeography influenced by shelf-basin exchange in the Arctic surface sediment at the Chukchi Borderland.

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    Han, Dukki; Nam, Seung-Il; Ha, Ho Kyung; Kim, Hyoungjun; Sadowsky, Michael J; Lee, Yoo Kyung; Hur, Hor-Gil

    2016-02-01

    It has been known that continental shelves around the Arctic Ocean play a major role in the ventilation of the deep basins as a consequence of shelf-basin exchange. In the present study, we found that bacterial assemblage of the surface sediment was different from that of seawater while seawater harboured local bacterial assemblages in response to the Arctic hydrography. This finding suggests that the Arctic seafloor sediments may have distinctive bacterial biogeography. Moreover, the distribution of bacterial assemblages and physicochemical properties in surface sediments changed gradually from the Arctic continental shelf to deep-sea basin. Based on the results, bacterial biogeography in the Arctic seafloor sediments may be influenced by winnowing and re-deposition of surface sediments through the sediment gravity flow. The present study offers a deeper understanding of shelf convection and its role for the construction of bacterial assemblages in the Arctic Ocean. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. The Drivers of the CH4 Seasonal Cycle in the Arctic and What Long-Term Observations of CH4 Imply About Trends in Arctic CH4 Fluxes

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    Sweeney, C.; Karion, A.; Bruhwiler, L.; Miller, J. B.; Wofsy, S. C.; Miller, C. E.; Chang, R. Y.; Dlugokencky, E. J.; Daube, B.; Pittman, J. V.; Dinardo, S. J.

    2012-12-01

    The large seasonal change in the atmospheric column for CH4 in the Arctic is driven by two dominant processes: transport of CH4 from low latitudes and surface emissions throughout the Arctic region. The NOAA ESRL Carbon Cycle Group Aircraft Program along with the NASA funded Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) have initiated an effort to better understand the factors controlling the seasonal changes in the mole fraction of CH4 in the Arctic with a multi-scale aircraft observing network in Alaska. The backbone of this network is multi-species flask sampling from 500 to 8000 masl that has been conducted every two weeks for the last 10 years over Poker Flat, AK. In addition regular profiles at the interior Alaska site at Poker Flat, NOAA has teamed up with the United States Coast Guard to make profiling flights with continuous observations of CO2, CO, CH4 and Ozone between Kodiak and Barrow every 2 weeks. More recently, CARVE has significantly added to this observational network with targeted flights focused on exploring the variability of CO2, CH4 and CO in the boundary layer both in the interior and the North Slope regions of Alaska. Taken together with the profiling of HIAPER Pole-to-Pole Observations (HIPPO), ground sites at Barrow and a new CARVE interior Alaska surface site just north of Fairbanks, AK, we now have the ability to investigate the full evolution of the seasonal cycle in the Arctic using both the multi-scale sampling offered by the different aircraft platforms as well as the multi-species sampling offered by in-situ and flask sampling. The flasks also provide a valuable tie-point between different platforms so that spatial and temporal gradients can be properly interpreted. In the context of the seasonal cycle observed by the aircraft platforms we will look at long term ground observations over the last 20 years to assess changes in Arctic CH4 emissions which have occurred as a result of 0.6C/decade changes in mean surface

  9. Thermophilic anaerobes in arctic marine sediments induced to mineralize complex organic matter at high temperature

    DEFF Research Database (Denmark)

    Hubert, Casey; Arnosti, Carol; Brüchert, Volker

    2010-01-01

    Marine sediments harbour diverse populations of dormant thermophilic bacterial spores that become active in sediment incubation experiments at much higher than in situ temperature. This response was investigated in the presence of natural complex organic matter in sediments of two Arctic fjords......, as well as with the addition of freeze-dried Spirulina or individual high-molecular-weight polysaccharides. During 50°C incubation experiments, Arctic thermophiles catalysed extensive mineralization of the organic matter via extracellular enzymatic hydrolysis, fermentation and sulfate reduction. This high...... reactivity determined the extent of the thermophilic response. Fjord sediments with higher in situ SRR also supported higher SRR at 50°C. Amendment with Spirulina significantly increased volatile fatty acids production and SRR relative to unamended sediment in 50°C incubations. Spirulina amendment also...

  10. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    Science.gov (United States)

    Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  11. Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

    Directory of Open Access Journals (Sweden)

    Jorien E Vonk

    2016-08-01

    Full Text Available Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C and molecular organic geochemistry (lignin, leaf waxes. High-resolution age models (137Cs, 210Pb of downcore lake sediment records (n=11 along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels. Comparison with earlier published Mackenzie River depth profiles shows that (i lake sediments reflect the riverine surface suspended load, and (ii hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

  12. Fitting sediment rating curves using regression analysis: a case study of Russian Arctic rivers

    Directory of Open Access Journals (Sweden)

    N. I. Tananaev

    2015-03-01

    Full Text Available Published suspended sediment data for Arctic rivers is scarce. Suspended sediment rating curves for three medium to large rivers of the Russian Arctic were obtained using various curve-fitting techniques. Due to the biased sampling strategy, the raw datasets do not exhibit log-normal distribution, which restricts the applicability of a log-transformed linear fit. Non-linear (power model coefficients were estimated using the Levenberg-Marquardt, Nelder-Mead and Hooke-Jeeves algorithms, all of which generally showed close agreement. A non-linear power model employing the Levenberg-Marquardt parameter evaluation algorithm was identified as an optimal statistical solution of the problem. Long-term annual suspended sediment loads estimated using the non-linear power model are, in general, consistent with previously published results.

  13. Fitting sediment rating curves using regression analysis: a case study of Russian Arctic rivers

    Science.gov (United States)

    Tananaev, N. I.

    2015-03-01

    Published suspended sediment data for Arctic rivers is scarce. Suspended sediment rating curves for three medium to large rivers of the Russian Arctic were obtained using various curve-fitting techniques. Due to the biased sampling strategy, the raw datasets do not exhibit log-normal distribution, which restricts the applicability of a log-transformed linear fit. Non-linear (power) model coefficients were estimated using the Levenberg-Marquardt, Nelder-Mead and Hooke-Jeeves algorithms, all of which generally showed close agreement. A non-linear power model employing the Levenberg-Marquardt parameter evaluation algorithm was identified as an optimal statistical solution of the problem. Long-term annual suspended sediment loads estimated using the non-linear power model are, in general, consistent with previously published results.

  14. Microbial diversity in Cenozoic sediments recovered from the Lomonosov Ridge in the Central Arctic basin.

    Science.gov (United States)

    Forschner, Stephanie R; Sheffer, Roberta; Rowley, David C; Smith, David C

    2009-03-01

    The current understanding of microbes inhabiting deeply buried marine sediments is based largely on samples collected from continental shelves in tropical and temperate latitudes. The geographical range of marine subsurface coring was expanded during the Integrated Ocean Drilling Program Arctic Coring Expedition (IODP ACEX). This expedition to the ice-covered central Arctic Ocean successfully cored the entire 428 m sediment stack on the Lomonosov Ridge during August and September 2004. The recovered cores vary from siliciclastic sediment low in organic carbon ( 200 m below sea floor) sulfate reduction zone. The diversity of microbes within each zone was assessed using 16S rRNA phylogenetic markers. Bacterial 16S rRNA genes were successfully amplified from each of the biogeochemical zones, while archaea was only amplified from the deep sulfate reduction zone. The microbial communities at each zone are phylogenetically different and are most closely related to those from other deep subsurface environments.

  15. Community size and metabolic rates of psychrophilic sulfate-reducing bacteria in Arctic marine sediments

    DEFF Research Database (Denmark)

    Knoblauch, C.; Jørgensen, BB; Harder, J.

    1999-01-01

    The numbers of sulfate reducers in two Arctic sediments within situ temperatures of 2.6 and -1.7 degrees C were determined. Most-probable-number counts were higher at 10 degrees C than at 20 degrees C, indicating the predominance of a psychrophilic community. Mean specific sulfate reduction rates...... of 19 isolated psychrophiles were compared to corresponding rates of 9 marine, mesophilic sulfate-reducing bacteria. The results indicate that, as a physiological adaptation to the permanently cold Arctic environment, psychrophilic sulfate reducers have considerably higher specific metabolic rates than...... their mesophilic counterparts at similarly low temperatures....

  16. Shifts in identity and activity of methanotrophs in arctic lake sediments in response to temperature changes

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    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperaturesincrease, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is importantto predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), andpyrosequencing analyses to identify and characterize methanotrophic communities active at a range of temperatures (4°C, 10°C,and 21°C) in sediments (to a depth of 25 cm) sampled from Lake Qalluuraq on the North Slope of Alaska. CH4 oxidation activitywas measured in microcosm incubations containing sediments at all temperatures, with the highest CH4 oxidation potential of37.5 mol g1 day1 in the uppermost (depth, 0 to 1 cm) sediment at 21°C after 2 to 5 days of incubation. Q-PCR of pmoA and ofthe 16S rRNA genes of type I and type II methanotrophs, and pyrosequencing of 16S rRNA genes in 13C-labeled DNA obtained bySIP demonstrated that the type I methanotrophs Methylobacter, Methylomonas, and Methylosoma dominated carbon acquisitionfrom CH4 in the sediments. The identity and relative abundance of active methanotrophs differed with the incubation temperature.Methylotrophs were also abundant in the microbial community that derived carbon from CH4, especially in the deeper sediments(depth, 15 to 20 cm) at low temperatures (4°C and 10°C), and showed a good linear relationship (R0.82) with the relativeabundances of methanotrophs in pyrosequencing reads. This study describes for the first time how methanotrophiccommunities in arctic lake sediments respond to temperature variations.

  17. Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)

    Science.gov (United States)

    Hindshaw, Ruth S.; Tosca, Nicholas J.; Piotrowski, Alexander M.; Tipper, Edward T.

    2018-03-01

    The identification of sediment sources to the ocean is a prerequisite to using marine sediment cores to extract information on past climate and ocean circulation. Sr and Nd isotopes are classical tools with which to trace source provenance. Despite considerable interest in the Arctic Ocean, the circum-Arctic source regions are poorly characterised in terms of their Sr and Nd isotopic compositions. In this study we present Sr and Nd isotope data from the Paleogene Central Basin sediments of Svalbard, including the first published data of stream suspended sediments from Svalbard. The stream suspended sediments exhibit considerable isotopic variation (ɛNd = -20.6 to -13.4; 87Sr / 86Sr = 0.73421 to 0.74704) which can be related to the depositional history of the sedimentary formations from which they are derived. In combination with analysis of the clay mineralogy of catchment rocks and sediments, we suggest that the Central Basin sedimentary rocks were derived from two sources. One source is Proterozoic sediments derived from Greenlandic basement rocks which are rich in illite and have high 87Sr / 86Sr and low ɛNd values. The second source is Carboniferous to Jurassic sediments derived from Siberian basalts which are rich in smectite and have low 87Sr / 86Sr and high ɛNd values. Due to a change in depositional conditions throughout the Paleogene (from deep sea to continental) the relative proportions of these two sources vary in the Central Basin formations. The modern stream suspended sediment isotopic composition is then controlled by modern processes, in particular glaciation, which determines the present-day exposure of the formations and therefore the relative contribution of each formation to the stream suspended sediment load. This study demonstrates that the Nd isotopic composition of stream suspended sediments exhibits seasonal variation, which likely mirrors longer-term hydrological changes, with implications for source provenance studies based on fixed

  18. Testing a laser-induced breakdown spectroscopy technique on the Arctic sediments

    Science.gov (United States)

    Han, D.; Nam, S. I.

    2017-12-01

    Physical and geochemical investigations coupled with the Laser-induced Breakdown Spectroscopy (LIBS) were performed on three surface sediment cores (ARA03B/24BOX, ARA02B/01(A)MUC, ARA02B/02MUC and ARA02B/03(A)MUC) recovered from the western Arctic Ocean (Chukchi Sea) during IBRV ARON expeditions in 2012. The LIBS technique was applied to carry out elemental chemical analysis of the Arctic sediments and compared with that measured by ITRAX X-ray fuorescence (XRF) core scanning. LIBS and XRF have shown similar elemental composition within each sediment core. In this study, mineral composition (XRD), grain size distribution and organic carbon content as well as elemental composition (LIBS) were all considered to understand paleoenvironmental changes (ocean circulation, sea-ice drift, iceberg discharge, and etc.) recorded in the Arctic Holocene sediment. Quantitative LIBS analysis shows a gradually varying distribution of the elements along the sampled core and clear separation between the cores. The cores are geochemically characterized by elevated Mn profile. The gradient of mineral composition and grain sizes among the cores shows regional distribution and variation in sedimentary condition due to geological distance between East Siberian and North America. The present study reveals that a LIBS technique can be employed for in-situ sediment analyses for the Arctic Ocean. Furthermore, LIBS does not require costly equipment, trained operators, and complicated sample pre-treatment processes compared to Atomic absorption spectroscopy (AAS) and inductively coupled plasma emission spectroscopy (ICP), and also known to show relatively high levels of sensitivity, precision, and distinction than XRF analysis, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and electron probe X-ray microanalysis (EPMA).

  19. Distribution of branched GDGTs in surface sediments from the Colville River, Alaska: Implications for the MBT'/CBT paleothermometer in Arctic marine sediments

    Science.gov (United States)

    Hanna, Andrea J. M.; Shanahan, Timothy M.; Allison, Mead A.

    2016-07-01

    Significant climate fluctuations in the Arctic over the recent past, and additional predicted future temperature changes, highlight the need for high-resolution Arctic paleoclimate records. Arctic coastal environments supplied with terrigenous sediment from Arctic rivers have the potential to provide annual to subdecadal resolution records of climate variability over the last few millennia. A potential tool for paleotemperature reconstructions in these marine sediments is the revised methylation index of branched tetraethers (MBT')/cyclization ratio of branched tetraethers (CBT) proxy based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). In this study, we examine the source of brGDGTs in the Colville River, Alaska, and the adjacent Simpson Lagoon and reconstruct temperatures from Simpson Lagoon sediments to evaluate the applicability of this proxy in Arctic estuarine environments. The Colville catchment soils, fluvial sediments, and estuarine sediments contain statistically similar brGDGT distributions, indicating that the brGDGTs throughout the system are soil derived with little alteration from in situ brGDGT production in the river or coastal waters. Temperatures reconstructed from the MBT'/CBT indices for surface samples show good agreement with regional summer (June through September) temperatures, suggesting a seasonal bias in Arctic temperature reconstructions from the Colville system. In addition, we reconstruct paleotemperatures from an estuarine sediment core that spans the last 75 years, revealing an overall warming trend in the twentieth century that is consistent with trends observed in regional instrumental records. These results support the application of this brGDGT-based paleotemperature proxy for subdecadal-scale summer temperature reconstructions in Arctic estuaries containing organic material derived from sediment-laden, episodic rivers.

  20. Biomarkers of Canadian High Arctic Litoral Sediments for Assessment of Organic Matter Sources and Degradation

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    Pautler, B. G.; Austin, J.; Otto, A.; Stewart, K.; Lamoureux, S. F.; Simpson, M. J.

    2009-05-01

    Carbon stocks in the High Arctic are particularly sensitive to global climate change, and investigation of variations in organic matter (OM) composition is beneficial for the understanding of the alteration of organic carbon under anticipated future elevated temperatures. Molecular-level characterization of solvent extractable compounds and CuO oxidation products of litoral sedimentary OM at the Cape Bounty Arctic Watershed Observatory in the Canadian Arctic Archipelago was conducted to determine the OM sources and decomposition patterns. The solvent extracts contained a series of aliphatic lipids, steroids and one triterpenoid primarily of higher plant origin and new biomarkers, iso- and anteiso-alkanes originating from cerastium arcticum (Arctic mouse-ear chickweed, a native angiosperm) were discovered. Carbon preference index (CPI) values for the n-alkanes, n-alkanols and n-alkanoic acids suggests that the OM biomarkers result from fresh material input in early stage of degradation. The CuO oxidation products were comprised of benzyls, lignin phenols and short-chain diacids and hydroxyacids. High abundance of terrestrial OM biomarkers observed at sites close to the river inlet suggests fluvial inputs as an important pathway to deliver OM into the lake. The lignin phenol vegetation index (LPVI) also suggests that the OM origin is mostly from non-woody angiosperms. A relatively high degree of lignin alteration in the litoral sediments is evident from the abundant ratio of acids and aldehydes of the vanillyl and syringyl monomers. This suggests that the lignin contents have been diagenetically altered as the result of a long residence time in this ecosystem. The molecular-level characterization of litoral sedimentary OM in Canadian High Arctic region provides insight into current OM composition,potential responses to future disturbances and the biogeochemical cycling of carbon in the Arctic.

  1. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    Science.gov (United States)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p  0.95, p CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

  2. Suspended sediment in a high-Arctic river

    DEFF Research Database (Denmark)

    Ladegaard-Pedersen, Pernille; Sigsgaard, Charlotte; Kroon, Aart

    2017-01-01

    -2012) of daily measurements from the high-Artic Zackenberg River in Northeast Greenland to estimate annual suspended sediment fluxes based on four commonly used methods: M1) is the discharge weighted mean and uses direct measurements, while M2-M4) are one uncorrected and two bias corrected rating curves......-1 and 61,000±16,000ty-1. Extreme events with high discharges had a mean duration of 1day. The average suspended sediment flux during extreme events was 17,000±5000ty-1, which constitutes a year-to-year variation of 20-37% of the total annual flux. The most accurate sampling strategy was bi...... extrapolating a continuous concentration trace from measured values. All methods are tested on complete and reduced datasets. The average annual runoff in the period 2005-2012 was 190±25mio·m3 y-1. The different estimation methods gave a range of average annual suspended sediment fluxes between 43,000±10,000ty...

  3. Chemometric Analysis for Pollution Source Assessment of Harbour Sediments in Arctic Locations

    DEFF Research Database (Denmark)

    Pedersen, Kristine B.; Lejon, Tore; Jensen, Pernille Erland

    2015-01-01

    Pollution levels, pollutant distribution and potential source assessments based on multivariate analysis (chemometrics) were made for harbour sediments from two Arctic locations; Hammerfest in Norway and Sisimiut in Greenland. High levels of heavy metals were detected in addition to organic...... pollutants. Preliminary assessments based on principal component analysis (PCA) revealed different sources and pollutant distribution in the sediments of the two harbours. Tributyltin (TBT) was, however, found to originate from point source(s), and the highest concentrations of TBT in both harbours were...... indicated relation primarily to German, Russian and American mixtures in Hammerfest; and American, Russian and Japanese mixtures in Sisimiut. PCA was shown to be an important tool for identifying pollutant sources and differences in pollutant composition in relation to sediment characteristics....

  4. Late-Middle Quaternary lithostratigraphy and sedimentation patterns on the Alpha Ridge, central Arctic Ocean: Implications for Arctic climate variability on orbital time scales

    Science.gov (United States)

    Wang, Rujian; Polyak, Leonid; Xiao, Wenshen; Wu, Li; Zhang, Taoliang; Sun, Yechen; Xu, Xiaomei

    2018-02-01

    We use sediment cores collected by the Chinese National Arctic Research Expeditions from the Alpha Ridge to advance Quaternary stratigraphy and paleoceanographic reconstructions for the Arctic Ocean. Our cores show a good litho/biostratigraphic correlation to sedimentary records developed earlier for the central Arctic Ocean, suggesting a recovered stratigraphic range of ca. 0.6 Ma, suitable for paleoclimatic studies on orbital time scales. This stratigraphy was tested by correlating the stacked Alpha Ridge record of bulk XRF manganese, calcium and zirconium (Mn, Ca, Zr), to global stable-isotope (LR04-δ18O) and sea-level stacks and tuning to orbital parameters. Correlation results corroborate the applicability of presumed climate/sea-level controlled Mn variations in the Arctic Ocean for orbital tuning. This approach enables better understanding of the global and orbital controls on the Arctic climate. Orbital tuning experiments for our records indicate strong eccentricity (100-kyr) and precession (∼20-kyr) controls on the Arctic Ocean, probably implemented via glaciations and sea ice. Provenance proxies like Ca and Zr are shown to be unsuitable as orbital tuning tools, but useful as indicators of glacial/deglacial processes and circulation patterns in the Arctic Ocean. Their variations suggest an overall long-term persistence of the Beaufort Gyre circulation in the Alpha Ridge region. Some glacial intervals, e.g., MIS 6 and 4/3, are predominated by material presumably transported by the Transpolar Drift. These circulation shifts likely indicate major changes in the Arctic climatic regime, which yet need to be investigated. Overall, our results demonstrate applicability of XRF data to paleoclimatic studies of the Arctic Ocean.

  5. Organophosphate Ester Flame Retardants and Plasticizers in Ocean Sediments from the North Pacific to the Arctic Ocean.

    Science.gov (United States)

    Ma, Yuxin; Xie, Zhiyong; Lohmann, Rainer; Mi, Wenying; Gao, Guoping

    2017-04-04

    The presence of organophosphate ester (OPE) flame retardants and plasticizers in surface sediment from the North Pacific to Arctic Ocean was observed for the first time during the fourth National Arctic Research Expedition of China in the summer of 2010. The samples were analyzed for three halogenated OPEs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(dichloroisopropyl) phosphate], three alkylated OPEs [triisobutyl phosphate (TiBP), tri-n-butyl phosphate, and tripentyl phosphate], and triphenyl phosphate. Σ 7 OPEs (total concentration of the observed OPEs) was in the range of 159-4658 pg/g of dry weight. Halogenated OPEs were generally more abundant than the nonhalogenated OPEs; TCEP and TiBP dominated the overall concentrations. Except for that of the Bering Sea, Σ 7 OPEs values increased with increasing latitudes from Bering Strait to the Central Arctic Ocean, while the contributions of halogenated OPEs (typically TCEP and TCPP) to the total OPE profile also increased from the Bering Strait to the Central Arctic Ocean, indicating they are more likely to be transported to the remote Arctic. The median budget of 52 (range of 17-292) tons for Σ 7 OPEs in sediment from the Central Arctic Ocean represents only a very small amount of their total production volume, yet the amount of OPEs in Arctic Ocean sediment was significantly larger than the sum of polybrominated diphenyl ethers (PBDEs) in the sediment, indicating they are equally prone to long-range transport away from source regions. Given the increasing level of production and usage of OPEs as substitutes of PBDEs, OPEs will continue to accumulate in the remote Arctic.

  6. Inundation, sedimentation, and subsidence creates goose habitat along the Arctic coast of Alaska

    Science.gov (United States)

    Tape, Ken D.; Flint, Paul L.; Meixell, Brandt W.; Gaglioti, Benjamin V.

    2013-01-01

    The Arctic Coastal Plain of Alaska is characterized by thermokarst lakes and drained lake basins, and the rate of coastal erosion has increased during the last half-century. Portions of the coast are sea level for kilometers inland, and are underlain by ice-rich permafrost. Increased storm surges or terrestrial subsidence would therefore expand the area subject to marine inundation. Since 1976, the distribution of molting Black Brant (Branta bernicla nigricans) on the Arctic Coastal Plain has shifted from inland freshwater lakes to coastal marshes, such as those occupying the Smith River and Garry Creek estuaries. We hypothesized that the movement of geese from inland lakes was caused by an expansion of high quality goose forage in coastal areas. We examined the recent history of vegetation and geomorphological changes in coastal goose habitat by combining analysis of time series imagery between 1948 and 2010 with soil stratigraphy dated using bomb-curve radiocarbon. Time series of vertical imagery and in situ verification showed permafrost thaw and subsidence of polygonal tundra. Soil stratigraphy and dating within coastal estuaries showed that non-saline vegetation communities were buried by multiple sedimentation episodes between 1948 and 1995, accompanying a shift toward salt-tolerant vegetation. This sedimentation allowed high quality goose forage plants to expand, thus facilitating the shift in goose distribution. Declining sea ice and the increasing rate of terrestrial inundation, sedimentation, and subsidence in coastal estuaries of Alaska may portend a 'tipping point' whereby inland areas would be transformed into salt marshes.

  7. Contamination of arctic Fjord sediments by Pb-Zn mining at Maarmorilik in central West Greenland

    DEFF Research Database (Denmark)

    Perner, Kerstin; Leipe, Thomas; Dellwig, O

    2010-01-01

    This study focuses on heavy metal contamination of arctic sediments from a small Fjord system adjacent to the Pb-Zn "Black Angel" mine (West Greenland) to investigate the temporal and spatial development of contamination and to provide baseline levels before the mines re-opening in January 2009....... Maximum contents were found at 12 cm depth in Affarlikassaa. After 17 years the mine last closed, specific local hydrographic conditions continue to disperse heavy metal enriched material derived from the Affarlikassaa into Qaumarujuk. Total Hg profiles from multi-cores along the transect clearly...

  8. Sediment bacterial community structures and their predicted functions implied the impacts from natural processes and anthropogenic activities in coastal area.

    Science.gov (United States)

    Su, Zhiguo; Dai, Tianjiao; Tang, Yushi; Tao, Yile; Huang, Bei; Mu, Qinglin; Wen, Donghui

    2018-06-01

    Coastal ecosystem structures and functions are changing under natural and anthropogenic influences. In this study, surface sediment samples were collected from disturbed zone (DZ), near estuary zone (NEZ), and far estuary zone (FEZ) of Hangzhou Bay, one of the most seriously polluted bays in China. The bacterial community structures and predicted functions varied significantly in different zones. Firmicutes were found most abundantly in DZ, highlighting the impacts of anthropogenic activities. Sediment total phosphorus was most influential on the bacterial community structures. Predicted by PICRUSt analysis, DZ significantly exceeded FEZ and NEZ in the subcategory of Xenobiotics Biodegradation and Metabolism; and DZ enriched all the nitrate reduction related genes, except nrfA gene. Seawater salinity and inorganic nitrogen, respectively as the representative natural and anthropogenic factor, performed exact-oppositely in nitrogen metabolism functions. The changes of bacterial community compositions and predicted functions provide a new insight into human-induced pollution impacts on coastal ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Isolation and Physiological Characterization of Psychrophilic Denitrifying Bacteria from Permanently Cold Arctic Fjord Sediments (Svalbard, Norway)

    Science.gov (United States)

    Canion, Andy; Prakash, Om; Green, Stefan J.; Jahnke, Linda; Kuypers, Marcel M. M.; Kostka, Joel E.

    2013-01-01

    A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(sup 3)-10(sup 6) cells of psychrophilic nitrate-respiring bacteria g(sup -1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40 degC demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15 degC, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

  10. Temperature induced decoupling of enzymatic hydrolysis and carbon remineralization in long-term incubations of Arctic and temperate sediments

    DEFF Research Database (Denmark)

    Robador, Alberto; Brüchert, Volker; Steen, Andrew

    2010-01-01

    explored the temperature sensitivity of enzymatic hydrolysis and its connection to subsequent steps in anoxic organic carbon degradation in long-term incubations of sediments from the Arctic and the North Sea. These sediments were incubated under anaerobic conditions for 24 months at temperatures of 0, 10......, and 20 ºC. The short-term temperature response of the active microbial community was tested in temperature gradient block incubations. The temperature optimum of extracellular enzymatic hydrolysis, as measured with a polysaccharide (chondroitin sulfate), differed between Arctic and temperate habitats...

  11. Microbial diversity in oiled and un-oiled shoreline sediments in the Norwegian Arctic

    International Nuclear Information System (INIS)

    Grossman, M.J.; Prince, R.C.; Garrett, R.M.; Garrett, K.K.; Bare, R.E.; O'Neil, K.R.; Sowlay, M.R.; Hinton, S.M.; Lee, K.; Sergy, G.A.; Guenette, C.C.

    2000-01-01

    Field trials were conducted at an oiled shoreline on the island of Spitsbergen to examine the effect of nutrient addition on the metabolic status, potential for aromatic hydrocarbon degradation, and the phylogenetic diversity of the microbial community in oiled Arctic shoreline sediments. IF-30 intermediate fuel grade oil was applied to the shoreline which was then divided into four plots. One was left untreated and two were tilled. Four applications of fertilizer were applied over a two-month period. Phospholipid fatty acid (PLFA), gene probe and 16S microbial community analysis suggested that bioremediation stimulated the metabolic activity, increased microbial biomass and genetic potential for aromatic hydrocarbon degradation, and increased the population of hydrocarbon degradation of an oiled Arctic shoreline microbial community. The results of this study are in agreement with the results from stimulation of oil biodegradation in temperate marine environments. It was concluded that biodegradation and fertilizer addition are feasible treatment methods for oil spills in Arctic regions. 31 refs., 3 tabs., 3 figs

  12. Organic carbon degradation in arctic marine sediments, Svalbard: A comparison of initial and terminal steps

    DEFF Research Database (Denmark)

    Arnosti, C.; Jørgensen, BB

    2006-01-01

    carbohydrate concentrations were comparable to those measured in more temperate sediments, and likely comprise a considerable fraction of porewater dissolved organic carbon. A comparison of dissolved carbohydrate inventories with hydrolysis and sulfate reduction rates suggests that the turnover of carbon......Degradation of marine organic matter under anoxic conditions involves microbial communities working in concert to remineralize complex substrates to CO2. In order to investigate the coupling between the initial and terminal steps of this sequence in permanently cold sediments, rates...... of extracellular enzymatic hydrolysis and sulfate reduction were measured in parallel cores collected from 5 fjords on the west and northwest coast of Svalbard, in the high Arctic. Inventories of total dissolved carbohydrates were also measured in order to evaluate their potential role in carbon turnover...

  13. Inundation, sedimentation, and subsidence creates goose habitat along the Arctic coast of Alaska

    International Nuclear Information System (INIS)

    Tape, Ken D; Flint, Paul L; Meixell, Brandt W; Gaglioti, Benjamin V

    2013-01-01

    The Arctic Coastal Plain of Alaska is characterized by thermokarst lakes and drained lake basins, and the rate of coastal erosion has increased during the last half-century. Portions of the coast are <1 m above sea level for kilometers inland, and are underlain by ice-rich permafrost. Increased storm surges or terrestrial subsidence would therefore expand the area subject to marine inundation. Since 1976, the distribution of molting Black Brant (Branta bernicla nigricans) on the Arctic Coastal Plain has shifted from inland freshwater lakes to coastal marshes, such as those occupying the Smith River and Garry Creek estuaries. We hypothesized that the movement of geese from inland lakes was caused by an expansion of high quality goose forage in coastal areas. We examined the recent history of vegetation and geomorphological changes in coastal goose habitat by combining analysis of time series imagery between 1948 and 2010 with soil stratigraphy dated using bomb-curve radiocarbon. Time series of vertical imagery and in situ verification showed permafrost thaw and subsidence of polygonal tundra. Soil stratigraphy and dating within coastal estuaries showed that non-saline vegetation communities were buried by multiple sedimentation episodes between 1948 and 1995, accompanying a shift toward salt-tolerant vegetation. This sedimentation allowed high quality goose forage plants to expand, thus facilitating the shift in goose distribution. Declining sea ice and the increasing rate of terrestrial inundation, sedimentation, and subsidence in coastal estuaries of Alaska may portend a ‘tipping point’ whereby inland areas would be transformed into salt marshes. (letter)

  14. Nondestructive X-Ray Computed Tomography Analysis of Sediment Cores: A Case Study from the Arctic Ocean

    Science.gov (United States)

    Oti, E.; Polyak, L. V.; Cook, A.; Dipre, G.

    2014-12-01

    Investigation of marine sediment records can help elucidate recent changes in the Arctic Ocean circulation and sea ice conditions. We examine sediment cores from the western Arctic Ocean, representing Late to Early Quaternary age (potentially up to 1 Ma). Previous studies of Arctic sediment cores indicate that interglacial/interstadial periods with relatively high sea levels and reduced ice cover are characterized by vigorous bioturbation, while glacial intervals have little to no bioturbation. Traditional methods for studying bioturbation require physical dissection of the cores, effectively destroying them. To treat this limitation, we evaluate archival sections of the cores using an X-ray Computed Tomography (XCT) scanner, which noninvasively images the sediment cores in three dimensions. The scanner produces density sensitive images suitable for quantitative analysis and for identification of bioturbation based on size, shape, and orientation. We use image processing software to isolate burrows from surrounding sediment, reconstruct them three-dimensionally, and then calculate their surface areas, volumes, and densities. Preliminary analysis of a core extending to the early Quaternary shows that bioturbation ranges from 0 to approximately 20% of the core's volume. In future research, we will quantitatively define the relationship between bioturbation activity and glacial regimes. XCT examination of bioturbation and other sedimentary features has the potential to shed light on paleoceanographic conditions such as sedimentation patterns and food flux. XCT is an alternative, underexplored investigation method that bears implications not only for illustrating paleoclimate variations but also for preserving cores for future, more advanced technologies.

  15. Desulfuromonas svalbardensis sp. nov. and Desulfuromusa ferrireducens sp. nov., psychrophilic, Fe(III)-reducing bacteria isolated from Arctic sediments, Svalbard

    DEFF Research Database (Denmark)

    Vandieken, Verona; Mussmann, Marc; Niemann, Helge

    2006-01-01

    Two psychrophilic, Gram-negative, rod-shaped, motile bacteria (strains 112T and 102T) that conserved energy from dissimilatory Fe(III) reduction concomitant with acetate oxidation were isolated from permanently cold Arctic marine sediments. Both strains grew at temperatures down to -2 degrees C...

  16. Desulfuromonas svalbardensis sp nov and Desulfuromusa ferrireducens sp nov., psychrophilic, Fe(III)-reducing bacteria isolated from Arctic sediments, Svalbard

    DEFF Research Database (Denmark)

    Vandieken, V.; Mussmann, M.; Niemann, Hans Henrik

    2006-01-01

    Two psychrophilic, Gram-negative, rod-shaped, motile bacteria (strains 112(T) and 102(T)) that conserved energy from dissimilatory Fe(III) reduction concomitant with acetate oxidation were isolated from permanently cold Arctic marine sediments. Both strains grew at temperatures down to -2 degrees C...

  17. Late quaternary palaeo-oceanography and palaeo-climatology from sediment cores of the eastern Arctic Ocean

    International Nuclear Information System (INIS)

    Pagels, U.; Koehler, S.

    1991-01-01

    Box cores recovered along a N-S transect in the Eurasian Basin allow the establishment of a time scale for the Late Quaternary history of the Arctic Ocean, based on stable oxygen isotope stratigraphy and AMS 14 C dating of planktonic foraminifers (N. pachyderma I.c.). This high resolution stratigraphy, in combination with sedimentological investigations (e.g. coarse fraction analysis, carbonate content, productivity of foraminifers), was carried out to reconstruct the glacial and inter-glacial Arctic Ocean palaeo-environment The sediment cores, which can be correlated throughout the sampling area in the Eastern Arctic Ocean, were dated as representing oxygen isotope stages 1 to 4/5. The sedimentation rates varied between a few mm/ka in glacials and approximately one cm/ka during the Holocene. The sediments allow a detailed sedimentological description of the depositional regime and the palaeo-oceanography of the Eastern Arctic Ocean. Changing ratios of biogenic and lithogenic components in the sediments reflect variations in the oceanographic circulation pattern in the Eurasian Basin during the Late Quaternary. Carbonate content (1-9wt.%), productivity of foraminifers (high in interglacial, low in glacial stages) and the terrigenous components are in good correlation with glacial and inter-glacial climatic fluctuations

  18. Persistent toxic substances in remote lake and coastal sediments from Svalbard, Norwegian Arctic: Levels, sources and fluxes

    International Nuclear Information System (INIS)

    Jiao Liping; Zheng, Gene J.; Minh, Tu Binh; Richardson, Bruce; Chen Liqi; Zhang Yuanhui; Yeung, Leo W.; Lam, James C.W.; Yan, Xulin; Lam, Paul K.S.; Wong, Ming H.

    2009-01-01

    Surface sediments from remote lakes and coastal areas from Ny-Alesund, Svalbard, Norwegian Arctic were analyzed for polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Relatively high levels of PAHs were encountered from several lakes from Ny-Alesund, which were within the range of levels reported for European high mountain lakes and some urban/industrialized areas in the world, pointing to the role of remote Arctic lakes as potential reservoir of semi-volatile organic compounds. Specific patterns of PBDEs were observed, showing higher concentrations of lower brominated compounds such as BDE-7, 17 and 28. Estimated surface sediment fluxes of PAHs in Ny-Alesund remote lakes were similar to those observed for some European high mountain lakes. The current PAH levels in sediments from three lakes exceeded Canadian sediment quality guidelines, suggesting the presence of possible risks for aquatic organisms and the need for further studies. - High levels of PAHs and specific patterns of PBDEs were found in sediments from the remote Norwegian Arctic lakes

  19. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Deglacial remobilization of permafrost carbon to sediments along the East Siberian Arctic Seas

    Science.gov (United States)

    Martens, J.; Wild, B.; Bröder, L.; Andersson, A.; Pearce, C.; O'Regan, M.; Jakobsson, M.; Tesi, T.; Muschitiello, F.; Sköld, M.; Semiletov, I. P.; Dudarev, O.; Gustafsson, O.

    2017-12-01

    Current climate change is expected to thaw large quantities of permafrost carbon (PF-C) and expose it to degradation which emits greenhouse gases (i.e. CO2 and CH4). Warming causes a gradual deepening of the seasonally thawed active layer surface of permafrost soils, but also the abrupt collapse of deeper Ice Complex Deposits (ICD), especially along Siberian coastlines. It was recently hypothesized that past warming already induced large-scale permafrost degradation after the last glacial, which ultimately amplified climate forcing. We here assess the mobilization of PF-C to East Siberian Arctic Sea sediments during these warming periods. We perform source apportionment using bulk carbon isotopes (ΔΔ14C, δ13C) together with terrestrial biomarkers (CuO-derived lignin phenols) as indicators for PF-C transfer. We apply these techniques to sediment cores (SWERUS-L2) from the Chukchi Sea (4-PC1) and the southern Lomonosov Ridge (31-PC1). We found that PF-C fluxes during the Bølling-Allerød warming (14.7 to 12.7 cal ka BP), the Younger Dryas cooling (12.7 to 11.7 cal ka BP) and the early Holocene warming (until 11 cal ka BP) were overall higher than mid and late Holocene fluxes. In the Chukchi Sea, PF-C burial was 2x higher during the deglaciation (7.2 g m-2 a-1) than in the mid and late Holocene (3.6 g m-2 a-1), and ICD were the dominant source of PF-C (79.1%). Smaller fractions originated from the active layer (9.1%) and marine sources (11.7%). We conclude that thermo-erosion of ICD released large amounts of PF-C to the Chukchi Sea, likely driven by climate warming and the deglacial sea level rise. This contrasts to earlier analyses of Laptev Sea sediments where active layer material from river transport dominated the carbon flux. Preliminary data on lignin phenol concentrations of Lomonosov Ridge sediments suggest that the postglacial remobilization of PF-C was one order of magnitude higher (10x) than during both the preceding glacial and the subsequent Holocene

  1. Characterization of the terrigenous organic matter distribution in the bottom sediments of the East Siberian Arctic Shelf

    Science.gov (United States)

    Dudarev, Oleg; Charkin, Alexander; Semiletov, Igor; Gustafsson, Örjan; Vonk, Jorien; Sánchez-García, Laura

    2010-05-01

    The Arctic Ocean is a Mediterranean sea with exceptionally large shelves that account for approximately 50% of the total area of the enclosed ocean. Accordingly, the inorganic and organic character of the sediments both on the shelves and in the basins of the Arctic Ocean strongly reflect a pervasive influence from the surrounding land/thawing permafrost (Macdonald et al., 2008). The East Siberian Arctic Shelf (ESAS) is an enormous, shallow shelf that receives most of its particulate supply from coastal erosion A notable characteristic of the ESAS is an extremely large gradient of hydrological and biogeochemical parameters from Long Strait/Wrangell Island to the Lena River Delta that corresponds to geographically critical contrasts in the Arctic system where the Pacific and local shelf waters interact over the shelf (Semiletov et al., 2005). ESAS is clearly important region for storing and processing material that derives from the land and the sea. Here we synthesize the lithological and biogochemical data obtained in the ESAS by Laboratory of Arctic studies POI in cooperation with the IARC and SU during the last 10 years (1999-2009). Highest organic carbon (OC) concentrations in the surface sediment (up to 4w/w%) was found near mouths of major rivers (Lena, Yana, Indigirka, Alaseya, Kolyma), and near highly eroded coast (1-2 w/w %). .However, sedimentation over the major portion of shallow ESAS is dominated by coastal erosion not riverine runoff. It has been shown that contribution of terrestrial organic carbon (CTOM) is up to 100% in areas strongly impacted by coastal erosion. Lowest OC values (~0.1-0.5 w/w %) were found in the relic sediments of shoals (e.g. Semenovskaya, Vasilevskaya, and Diomid). New detail maps of distribution of sediment OC, CTOM, and C/N are considered along with the sediment sizing and mineralogical data. This multi-year study was supported by the Russian Foundation for Basic Research (Russian NSF), FEBRAS, NOAA, NSF, Wallenberg Foundation

  2. Trends in historical mercury deposition inferred from lake sediment cores across a climate gradient in the Canadian High Arctic.

    Science.gov (United States)

    Korosi, Jennifer B; Griffiths, Katherine; Smol, John P; Blais, Jules M

    2018-06-02

    Recent climate change may be enhancing mercury fluxes to Arctic lake sediments, confounding the use of sediment cores to reconstruct histories of atmospheric deposition. Assessing the independent effects of climate warming on mercury sequestration is challenging due to temporal overlap between warming temperatures and increased long-range transport of atmospheric mercury following the Industrial Revolution. We address this challenge by examining mercury trends in short cores (the last several hundred years) from eight lakes centered on Cape Herschel (Canadian High Arctic) that span a gradient in microclimates, including two lakes that have not yet been significantly altered by climate warming due to continued ice cover. Previous research on subfossil diatoms and inferred primary production indicated the timing of limnological responses to climate warming, which, due to prevailing ice cover conditions, varied from ∼1850 to ∼1990 for lakes that have undergone changes. We show that climate warming may have enhanced mercury deposition to lake sediments in one lake (Moraine Pond), while another (West Lake) showed a strong signal of post-industrial mercury enrichment without any corresponding limnological changes associated with warming. Our results provide insights into the role of climate warming and organic carbon cycling as drivers of mercury deposition to Arctic lake sediments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Uranium hydrogeochemical and stream sediment reconnaissance of the Arctic NTMS quadrangle, Alaska

    International Nuclear Information System (INIS)

    Shettel, D.L. Jr.; Langfeldt, S.L.; Youngquist, C.A.; D'Andrea, R.F. Jr.; Zinkl, R.J.

    1981-09-01

    This report presents results of a Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) of the Arctic NTMS quadrangle, Alaska. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form through the Grand Junction Office Information System at Oak Ridge National Laboratory. Presented in this data release are location data, field analyses, and laboratory analyses of several different sample media. For the sake of brevity, many field site observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendix A describes the sample media and summarizes the analytical results for each medium. The data were subdivided by one of the Los Alamos National Laboratory (LANL) sorting programs of Zinkl and others into stream sediment samples. For the group which contains a sufficient number of observations, statistical tables, tables of raw data, and 1:1000000 scale maps of pertinent elements have been included in this report. In addition, maps showing results of multivariate statistical analyses have been included. Further information about the HSSR program in general, or about the LANL portion of the program in particular, can be obtained in quarterly or semiannual program progress reports on open-file at DOE's Technical Library in Grand Junction. Information about the field and analytical procedures used by LANL during sample collection and analysis may be found in any HSSR data release prepared by the LANL and will not be included in this report

  4. Biogeographic patterns of bacterial microdiversity in Arctic deep-sea sediments (HAUSGARTEN, Fram Strait).

    Science.gov (United States)

    Buttigieg, Pier Luigi; Ramette, Alban

    2014-01-01

    Marine bacteria colonizing deep-sea sediments beneath the Arctic ocean, a rapidly changing ecosystem, have been shown to exhibit significant biogeographic patterns along transects spanning tens of kilometers and across water depths of several thousand meters (Jacob et al., 2013). Jacob et al. (2013) adopted what has become a classical view of microbial diversity - based on operational taxonomic units clustered at the 97% sequence identity level of the 16S rRNA gene - and observed a very large microbial community replacement at the HAUSGARTEN Long Term Ecological Research station (Eastern Fram Strait). Here, we revisited these data using the oligotyping approach and aimed to obtain new insight into ecological and biogeographic patterns associated with bacterial microdiversity in marine sediments. We also assessed the level of concordance of these insights with previously obtained results. Variation in oligotype dispersal range, relative abundance, co-occurrence, and taxonomic identity were related to environmental parameters such as water depth, biomass, and sedimentary pigment concentration. This study assesses ecological implications of the new microdiversity-based technique using a well-characterized dataset of high relevance for global change biology.

  5. Biogeographic patterns of bacterial microdiversity in Arctic deep-sea sediments (Hausgarten, Fram Strait

    Directory of Open Access Journals (Sweden)

    Pier Luigi eButtigieg

    2015-01-01

    Full Text Available Marine bacteria colonising deep-sea sediments beneath the Arctic ocean, a rapidly changing ecosystem, have been shown to exhibit significant biogeographic patterns along transects spanning tens of kilometres and across water depths reaching several thousands of metres (Jacob et al., 2013. Jacob et al. adopted what has become a classical view of microbial diversity based on operational taxonomic units clustered at the 97% sequence identity level of the 16S rRNA gene and observed a very large microbial community replacement at the Hausgarten Long-Term Ecological Research station (Eastern Fram Strait. Here, we revisited these data using the oligotyping approach with the aims of obtaining new insights into ecological and biogeographic patterns associated with bacterial microdiversity in marine sediments and of assessing the level of concordance of these insights with previously obtained results. Variation in oligotype dispersal range, relative abundance, co-occurrence, and taxonomic identity were related to environmental parameters such as water depth, biomass, and sedimentary pigment concentration. This study assesses ecological implications of the new microdiversity-based technique using a well-characterised dataset of high relevance for global change biology.

  6. Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

    Science.gov (United States)

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

  7. Soil Organic Carbon Stocks in Arctic Deltaic Sediments: Investigations in the Lena River Delta.

    Science.gov (United States)

    Zubrzycki, S.; Kutzbach, L.; Desyatkin, A.; Pfeiffer, E.-M.

    2012-04-01

    The soil organic carbon stock (SSOC) of deltaic sediments in arctic permafrost regions is known to be significant but is insufficiently investigated so far. Previous SSOC studies were conducted mainly in the comparatively well studied Mackenzie River Delta (area: 13,000 km2) in Canada. The few studies from other arctic delta regions report only the gravimetric carbon (C) contents and are limited to the active layer depth at the time of sampling. Since C deposits in permafrost regions are likely to become a future C source, more detailed investigations of the presently frozen likely carbon-rich sediment and soil layers in other arctic delta regions are of importance. Our investigations were performed on Samoylov Island in the southern-central part of the Lena River Delta (32,000 km2) which is the largest arctic delta and the fifth largest delta worldwide. Samoylov Island is representative for the Lena River Delta's first terrace and the active floodplains. Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE) auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 37) distributed over all known soil and vegetation units. These cores are analyzed for bulk contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC including the rarely investigated currently permanently frozen layers up to 1 m depth on Samoylov Island. Our study provides evidence for high SSOC for a depth of 1 m for the investigated area ranging between 6 kg m2 and 54 kg m2. Considering the spatial extent of different soil units on the two geomorphological units of Samoylov Island, the area-weighted average SSOC were 31 kg m2 (n = 31) for the first terrace and 15 kg m2 (n = 6) for the active floodplain. For the correspondent soil units of Turbels and Orthels in circumpolar permafrost regions, Tarnocai et al. 2009 reported a mean SSOC of 27 kg m2 (min: 0.1 kg m2, max: 126 kg m2) for a depth of 1 m. For up

  8. Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

    Science.gov (United States)

    Burke, Samantha M.; Zimmerman, Christian E.; Branfireun, Brian A.; Koch, Joshua C.; Swanson, Heidi K.

    2018-01-01

    The biogeochemical cycle of mercury will be influenced by climate change, particularly at higher latitudes. Investigations of historical mercury accumulation in lake sediments inform future predictions as to how climate change might affect mercury biogeochemistry; however, in regions with a paucity of data, such as the thermokarst-rich Arctic Coastal Plain of Alaska (ACP), the trajectory of mercury accumulation in lake sediments is particularly uncertain. Sediment cores from three thermokarst lakes on the ACP were analyzed to understand changes in, and drivers of, Hg accumulation over the past ~ 100 years. Mercury accumulation in two of the three lakes was variable and high over the past century (91.96 and 78.6 µg/m2/year), and largely controlled by sedimentation rate. Mercury accumulation in the third lake was lower (14.2 µg/m2/year), more temporally uniform, and was more strongly related to sediment Hg concentration than sedimentation rate. Sediment mercury concentrations were quantitatively related to measures of sediment composition and VRS-inferred chlorophyll a, and sedimentation rates were related to various catchment characteristics. These results were compared to data from 37 previously studied Arctic and Alaskan lakes. Results from the meta-analysis indicate that thermokarst lakes have significantly higher and more variable Hg accumulation rates than non-thermokarst lakes, suggesting that certain properties (e.g., thermal erosion, thaw slumping, low hydraulic conductivity) likely make lakes prone to high and variable Hg accumulation rates. Differences and high variability in Hg accumulation among high latitude lakes highlight the complexity of predicting future climate-related change impacts on mercury cycling in these environments.

  9. Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

    Science.gov (United States)

    Sparkes, Robert B.; Doğrul Selver, Ayça; Gustafsson, Örjan; Semiletov, Igor P.; Haghipour, Negar; Wacker, Lukas; Eglinton, Timothy I.; Talbot, Helen M.; van Dongen, Bart E.

    2016-10-01

    Mobilisation of terrestrial organic carbon (terrOC) from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS). Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis-gas chromatography-mass spectrometry (py-GCMS) to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p radiocarbon data for bulk OC (14COC) which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river-ocean transects of surface sediments transition from river-dominated to coastal-erosion-dominated to marine-dominated signatures.

  10. Acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in Arctic marine sediments, Svalbard

    DEFF Research Database (Denmark)

    Finke, Niko; Vandieken, Verona; Jørgensen, Bo Barker

    2007-01-01

    The contribution of volatile fatty acids (VFA) as e--donors for anaerobic terminal oxidation of organic carbon through iron and sulfate reduction was studied in Arctic fjord sediment. Dissolved inorganic carbon, Fe2+, VFA concentrations, and sulfate reduction were monitored in slurries from...... by alternative e--donors. The accumulation of VFA in the selenate-inhibited 0-2 cm slurry did not enhance iron reduction, indicating that iron reducers were not limited by VFA availability....

  11. Effect of recent climate change on Arctic Pb pollution: A comparative study of historical records in lake and peat sediments

    International Nuclear Information System (INIS)

    Liu Xiaodong; Jiang Shan; Zhang Pengfei; Xu Liqiang

    2012-01-01

    Historical changes of anthropogenic Pb pollution were reconstructed based on Pb concentrations and isotope ratios in lake and peat sediment profiles from Ny-Ålesund of Arctic. The calculated excess Pb isotope ratios showed that Pb pollution largely came from west Europe and Russia. The peat profile clearly reflected the historical changes of atmospheric deposition of anthropogenic Pb into Ny-Ålesund, and the result showed that anthropogenic Pb peaked at 1960s–1970s, and thereafter a significant recovery was observed by a rapid increase of 206 Pb/ 207 Pb ratios and a remarkable decrease in anthropogenic Pb contents. In contrast to the peat record, the longer lake record showed relatively high anthropogenic Pb contents and a persistent decrease of 206 Pb/ 207 Pb ratios within the uppermost samples, suggesting that climate-sensitive processes such as catchment erosion and meltwater runoff might have influenced the recent change of Pb pollution record in the High Arctic lake sediments. - Highlights: ► Historical changes of anthropogenic Pb pollution in Ny-Ålesund were reconstructed. ► Anthropogenic Pb in Ny-Ålesund was largely originated from W. European and Russia. ► Anthropogenic Pb recorded in peat sediments peaked at 1960–1970s and then declined. ► High anthropogenic fluxes were found in recent change of Pb record from lake sediments. ► Climate-sensitive processes might have influenced recent Pb accumulation rate in lakes. - This manuscript reports the effects of climate-sensitive processes on historical records of Pb pollution in sediments of Arctic lakes.

  12. Volatile fatty acids as substrates for iron and sulfate reduction in Arctic marine sediments, Svalbard

    Science.gov (United States)

    Finke, N.; Vandieken, V.; Jorgensen, B. B.

    2006-12-01

    Anaerobic degradation of complex organic material in aquatic systems is a multi-step process. The metabolic products of fermentative bacteria serve as electron donors for the terminal oxidizing bacteria. In marine sediments, iron reduction and sulfate reduction are generally the most important terminal oxidation processes in the upper anoxic zone [1]. Microorganisms that reduce iron and sulfate may use a broad range of electron donors, yet the list of potential substrates provides little information about the substrates used in situ by these organisms. Investigations on the electron donors for sulfate reducers in marine sediments have shown that volatile fatty acids (VFA), and in particular acetate, together with hydrogen are the major substrates (e.g. [2-4]). Similar investigations for iron reduction or simultaneous iron and sulfate reduction are lacking for marine sediments. Furthermore, most of these studies were made in temperate sediments and little is known about the substrates for sulfate reducers in permanently cold sediments, which account for >90% of the ocean floor [5]. We investigated the relative contributions of iron reduction and sulfate reduction to the terminal oxidation of organic carbon and the importance of acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in permanently cold, Arctic sediments from Svalbard. In the surface layer (0-2 cm) sulfate reduction accounted for 2/3 of the organic carbon oxidation (determined as DIC production), the remaining 1/3 were attributed to iron reduction. In the 5-9 cm layer sulfate reduction was the sole important terminal oxidation step. The contribution of acetate to terminal oxidation was determined by radiotracer incubation as well as from the accumulation after the inhibition of sulfate reduction by selenate. The rates determined with the two methods varied by less than 20%. Acetate turnover, determined with the tracer incubations, accounted for 10 and 40% of

  13. Viable Species of Flamella (Amoebozoa: Variosea) Isolated from Ancient Arctic Permafrost Sediments.

    Science.gov (United States)

    Shmakova, Lyubov; Bondarenko, Natalya; Smirnov, Alexey

    2016-02-01

    Six viable strains of amoebae belonging to the genus Flamella (Amoebozoa, Variosea) were isolated from permafrost sediments sampled in the Russian Arctic region. Two of them are from late Pleistocene permafrost in North-East Siberia, and four--from Holocene and late Pleistocene in North-West Siberia. Light- and electron-microscopic study and molecular phylogeny show that these isolates represent two new species belonging to the genus Flamella. Both species are cyst-forming. This is a remarkable case of high resistance of protozoan cysts, allowing them to survive and recover an amoebae population after a very long, geologically significant period of rest; a "snapshot" of evolution in time. This study directly shows for the first time that amoeba cysts can be conserved not only for years and decades but for many thousand years and then recover, contributing to the formation of an active microbial community. We propose to name the new species as Flamella pleistocenica n.sp. and Flamella beringiania n.sp. Phylogenetic analysis shows that the genus Flamella is a robust and potentially species-rich group of Variosea. Copyright © 2015 Elsevier GmbH. All rights reserved.

  14. Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

    Directory of Open Access Journals (Sweden)

    R. B. Sparkes

    2016-10-01

    Full Text Available Mobilisation of terrestrial organic carbon (terrOC from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS. Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis–gas chromatography–mass spectrometry (py-GCMS to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p < 0.01, n = 24. Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (14COC which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river–ocean transects of surface sediments transition from river-dominated to

  15. High activity and low temperature optima of extracellular enzymes in Arctic sediments: implications for carbon cycling by heterotrophic microbial communities

    DEFF Research Database (Denmark)

    Arnosti, C.; Jørgensen, BB

    2003-01-01

    The rate of the initial step in microbial remineralization of organic carbon, extracellular enzymatic hydrolysis, was investigated as a function of temperature in permanently cold sediments from 2 fjords on the west coast of Svalbard (Arctic Ocean). We used 4 structurally distinct polysaccharides...... hydrolysis in order to determine the relative temperature responses of the initial and terminal steps in microbial remineralization of carbon. The temperature optimum of sulfate reduction, 21degreesC, was considerably lower than previous reports of sulfate reduction in marine sediments, but is consistent...... with recent studies of psychrophilic sulfate reducers isolated from Svalbard sediments. A calculation of potential carbon flow into the microbial food chain demonstrated that the activity of just one type of polysaccharide-hydrolyzing enzyme could in theory supply 21 to 100% of the carbon consumed via sulfate...

  16. Community structure, cellular rRNA content, and activity of sulfate-reducing bacteria in marine Arctic sediments

    DEFF Research Database (Denmark)

    Ravenschlag, K.; Sahm, K.; Knoblauch, C.

    2000-01-01

    The community structure of sulfate-reducing bacteria (SRB) of a marine Arctic sediment (Smeerenburg-fjorden, Svalbard) a-as characterized by both fluorescence in situ hybridization (FISH) and rRNA slot blot hybridization by using group- and genus-specific 16S rRNA-targeted oligonucleotide probes...... that FISH and rRNA slot blot hybridization gave comparable results. Furthermore, a combination of the two methods allowed us to calculate specific cellular rRNA contents with respect to localization in the sediment profile. The rRNA contents of Desulfosarcina-Desulfococcus cells were highest in the first 5...... mm of the sediment (0.9 and 1.4 fg, respectively) and decreased steeply with depth, indicating that maximal metabolic activity occurred close to the surface, Based on SRB cell numbers, cellular sulfate reduction rates were calculated. The rates were highest in the surface layer (0.14 fmol cell(-1...

  17. Flocculation alters the distribution and flux of melt-water supplied sediments and nutrients in the Arctic

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest; Ernstsen, Verner Brandbyge

    In the Arctic, thawing permafrost and increased melting of glaciers are important drivers for changes in fine-grained sediment supply and biogeochemical fluxes from land to sea. Flocculation of particles is a controlling factor for the magnitude of fluxes and deposition rates in the marine...... environment but comparatively little is known about the flocculation processes in the Arctic. We investigated flocculation dynamics from a melt-water river in the inner Disko Fjord, West Greenland. A novel, laser-illuminated camera system significantly improved the particle size measurement capabilities...... and settling tubes were sampled to enable sub-sampling of different floc size fractions. Flocculation was observed during periods with low turbulent shear and also at the front of the fresh water plume resulting in significant volumes of large sized flocs at depth below the plume. The floc sizes and volumes...

  18. The impact of temperature change on the activity and community composition of sulfate-reducing bacteria in arctic versus temperate marine sediments

    DEFF Research Database (Denmark)

    Robador, Alberto; Brüchert, Volker; Jørgensen, Bo Barker

    2009-01-01

    Arctic regions may be particularly sensitive to climate warming and, consequently, rates of carbon mineralization in warming marine sediment may also be affected. Using long-term (24 months) incubation experiments at 0°C, 10°C and 20°C, the temperature response of metabolic activity and community...... composition of sulfate-reducing bacteria were studied in the permanently cold sediment of north-western Svalbard (Arctic Ocean) and compared with a temperate habitat with seasonally varying temperature (German Bight, North Sea). Short-term 35S-sulfate tracer incubations in a temperature-gradient block...... (between -3.5°C and +40°C) were used to assess variations in sulfate reduction rates during the course of the experiment. Warming of arctic sediment resulted in a gradual increase of the temperature optima (Topt) for sulfate reduction suggesting a positive selection of psychrotolerant/mesophilic sulfate...

  19. High activity and low temperature optima of extracellular enzymes in Arctic sediments: implications for carbon cycling by heterotrophic microbial communities

    DEFF Research Database (Denmark)

    Arnosti, C.; Jørgensen, BB

    2003-01-01

    (chondroitin sulfate, fucoidan, xylan and pullulan) to determine the temperature-activity responses of hydrolysis of a related class of compounds. All 4 enzyme activities showed similarly low temperature optima in the range of 15 to 18degreesC. These temperature optima are considerably lower than most previous......The rate of the initial step in microbial remineralization of organic carbon, extracellular enzymatic hydrolysis, was investigated as a function of temperature in permanently cold sediments from 2 fjords on the west coast of Svalbard (Arctic Ocean). We used 4 structurally distinct polysaccharides...... reports of temperature optima for enzyme activities in marine sediments. At 0degreesC, close to the in situ temperature, these enzyme activities achieved 13 to 38% of their rates at optimum temperatures. In one experiment, sulfate reduction rates were measured in parallel with extracellular enzymatic...

  20. Effect of recent climate change on Arctic Pb pollution: a comparative study of historical records in lake and peat sediments.

    Science.gov (United States)

    Liu, Xiaodong; Jiang, Shan; Zhang, Pengfei; Xu, Liqiang

    2012-01-01

    Historical changes of anthropogenic Pb pollution were reconstructed based on Pb concentrations and isotope ratios in lake and peat sediment profiles from Ny-Ålesund of Arctic. The calculated excess Pb isotope ratios showed that Pb pollution largely came from west Europe and Russia. The peat profile clearly reflected the historical changes of atmospheric deposition of anthropogenic Pb into Ny-Ålesund, and the result showed that anthropogenic Pb peaked at 1960s-1970s, and thereafter a significant recovery was observed by a rapid increase of (206)Pb/(207)Pb ratios and a remarkable decrease in anthropogenic Pb contents. In contrast to the peat record, the longer lake record showed relatively high anthropogenic Pb contents and a persistent decrease of (206)Pb/(207)Pb ratios within the uppermost samples, suggesting that climate-sensitive processes such as catchment erosion and meltwater runoff might have influenced the recent change of Pb pollution record in the High Arctic lake sediments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Diversity of kelp holdfast-associated fauna in an Arctic fjord - inconsistent responses to glacial mineral sedimentation across different taxa

    Science.gov (United States)

    Ronowicz, Marta; Kukliński, Piotr; Włodarska-Kowalczuk, Maria

    2018-05-01

    Kelp forests are complex underwater habitats that support diverse assemblages of animals ranging from sessile filter feeding invertebrates to fishes and marine mammals. In this study, the diversity of invertebrate fauna associated with kelp holdfasts was surveyed in a high Arctic glacial fjord (76 N, Hornsund, Svalbard). The effects of algal host identity (three kelp species: Laminaria digitata, Saccharina latissima and Alaria esculenta), depth (5 and 10 m) and glacier-derived disturbance (three sites with varying levels of mineral sedimentation) on faunal species richness and composition were studied based on 239 collected algal holdfasts. The species pool was mostly made up by three taxa: colonial Bryozoa and Hydrozoa, and Polychaeta. While the all-taxa species richness did not differ between depths, algal hosts and sites, the patterns varied when the two colonial sessile filter-feeding taxa were analysed alone (Hydrozoa and Bryozoa). The Hydrozoa sample species richness and average taxonomic distinctness were the highest at undisturbed sites, whereas Bryozoa species richness was higher in sediment-impacted localities, indicating relative insensitivity of this phylum to the increased level of mineral suspension in the water column. The average taxonomic distinctness of Bryozoa did not vary between sites. The species composition of kelp-associated fauna varied between sites and depths for the whole community and the most dominant taxa (Bryozoa, Hydrozoa). The high load of inorganic suspension and sedimentation did not cause pauperization of kelp holdfast-associated fauna but instead triggered the changes in species composition and shifts between dominant taxonomic groups.

  2. Can we constrain postglacial sedimentation in the western Arctic Ocean by ramped pyrolysis 14C? A case study from the Chukchi-Alaskan margin.

    Science.gov (United States)

    Suzuki, K.; Yamamoto, M.; Rosenheim, B. E.; Omori, T.; Polyak, L.; Nam, S. I.

    2017-12-01

    The Arctic Ocean underwent dramatic climate changes in the past. Variations in sea-ice extent and ocean current system in the Arctic cause changes in surface albedo and deep water formation, which have global climatic implications. However, Arctic paleoceanographic studies are lagging behind the other oceans due largely to chronostratigraphic difficulties. One of the reasons for this is a scant presence of material suitable for 14C dating in large areas of the Arctic seafloor. To enable improved age constraints for sediments impoverished in datable material, we apply ramped pyrolysis 14C method (Ramped PyrOx 14C, Rosenheim et al., 2008) to sedimentary records from the Chukchi-Alaska margin recovering Holocene to late-glacial deposits. Samples were divided into five fraction products by gradual heating sedimentary organic carbon from ambient laboratory temperature to 1000°C. The thermographs show a trimodal pattern of organic matter decomposition over temperature, and we consider that CO2 generated at the lowest temperature range was derived from autochthonous organic carbon contemporaneous with sediment deposition, similar to studies in the Antarctic margin and elsewhere. For verification of results, some of the samples treated for ramped pyrolysis 14C were taken from intervals dated earlier by AMS 14C using bivalve mollusks. Ultimately, our results allow a new appraisal of deglacial to Holocene deposition at the Chukchi-Alaska margin with potential to be applied to other regions of the Arctic Ocean.

  3. Regional variations in provenance and abundance of ice-rafted clasts in Arctic Ocean sediments: Implications for the configuration of late Quaternary oceanic and atmospheric circulation in the Arctic

    Science.gov (United States)

    Phillips, R.L.; Grantz, A.

    2001-01-01

    The composition and distribution of ice-rafted glacial erratics in late Quaternary sediments define the major current systems of the Arctic Ocean and identify two distinct continental sources for the erratics. In the southern Amerasia basin up to 70% of the erratics are dolostones and limestones (the Amerasia suite) that originated in the carbonate-rich Paleozoic terranes of the Canadian Arctic Islands. These clasts reached the Arctic Ocean in glaciers and were ice-rafted to the core sites in the clockwise Beaufort Gyre. The concentration of erratics decreases northward by 98% along the trend of the gyre from southeastern Canada basin to Makarov basin. The concentration of erratics then triples across the Makarov basin flank of Lomonosov Ridge and siltstone, sandstone and siliceous clasts become dominant in cores from the ridge and the Eurasia basin (the Eurasia suite). The bedrock source for the siltstone and sandstone clasts is uncertain, but bedrock distribution and the distribution of glaciation in northern Eurasia suggest the Taymyr Peninsula-Kara Sea regions. The pattern of clast distribution in the Arctic Ocean sediments and the sharp northward decrease in concentration of clasts of Canadian Arctic Island provenance in the Amerasia basin support the conclusion that the modem circulation pattern of the Arctic Ocean, with the Beaufort Gyre dominant in the Amerasia basin and the Transpolar drift dominant in the Eurasia basin, has controlled both sea-ice and glacial iceberg drift in the Arctic Ocean during interglacial intervals since at least the late Pleistocene. The abruptness of the change in both clast composition and concentration on the Makarov basin flank of Lomonosov Ridge also suggests that the boundary between the Beaufort Gyre and the Transpolar Drift has been relatively stable during interglacials since that time. Because the Beaufort Gyre is wind-driven our data, in conjunction with the westerly directed orientation of sand dunes that formed during

  4. Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. L. Ramage

    2018-03-01

    Full Text Available Retrogressive thaw slumps (RTSs are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1 describe the evolution of RTSs between 1952 and 2011; (2 calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC and dissolved organic carbon (DOC; and (3 estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high-resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73 % increase in the number of RTSs and 14 % areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6×106 m3 of material, 53 % of which was ice, and mobilized 145.9×106 kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6×103 m3 yr−1 of material, adding 0.6 % to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.

  5. Quantitative and phylogenetic study of the Deep Sea Archaeal Group in sediments of the arctic mid-ocean spreading ridge

    Directory of Open Access Journals (Sweden)

    Steffen Leth eJørgensen

    2013-10-01

    Full Text Available In marine sediments archaea often constitute a considerable part of the microbial community, of which the Deep Sea Archaeal Group (DSAG is one of the most predominant. Despite their high abundance no members from this archaeal group have so far been characterized and thus their metabolism is unknown. Here we show that the relative abundance of DSAG marker genes can be correlated with geochemical parameters, allowing prediction of both the potential electron donors and acceptors of these organisms. We estimated the abundance of 16S rRNA genes from Archaea, Bacteria and DSAG in 52 sediment horizons from two cores collected at the slow-spreading Arctic Mid-Ocean Ridge, using qPCR. The results indicate that members of the DSAG make up the entire archaeal population in certain horizons and constitute up to ~ 50% of the total microbial community. The quantitative data were correlated to 30 different geophysical and geochemical parameters obtained from the same sediment horizons. We observed a significant correlation between the relative abundance of DSAG 16S rRNA genes and the content of organic carbon (p < 0.0001. Further, significant co-variation with iron oxide, and dissolved iron and manganese (all p < 0.0000, indicated a direct or indirect link to iron and manganese cycling. Neither of these parameters correlated with the relative abundance of archaeal or bacterial 16S rRNA genes, nor did any other major electron donor or acceptor measured. Phylogenetic analysis of DSAG 16S rRNA gene sequences reveals three monophyletic lineages with no apparent habitat-specific distribution. In this study we support the hypothesis that members of the DSAG are tightly linked to the content of organic carbon and directly or indirectly involved in the cycling of iron and/or manganese compounds. Further, we provide a molecular tool to assess their abundance in environmental samples and enrichment cultures.

  6. Normalization for Implied Volatility

    OpenAIRE

    Fukasawa, Masaaki

    2010-01-01

    We study specific nonlinear transformations of the Black-Scholes implied volatility to show remarkable properties of the volatility surface. Model-free bounds on the implied volatility skew are given. Pricing formulas for the European options which are written in terms of the implied volatility are given. In particular, we prove elegant formulas for the fair strikes of the variance swap and the gamma swap.

  7. Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

    DEFF Research Database (Denmark)

    Arnosti, Carol; Finke, Niko; Larsen, Ole

    2005-01-01

    of activity that it fueled, its soluble nature, and its relatively high (50%) carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity to react rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar to observations made......Complex substrates are degraded in anoxic sediments by the concerted activities of diverse microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently cold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high...... which they were derived. Although Spirulina and Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate content), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbon was respired, despite the initial burst...

  8. Reconstruction of a high-resolution late holocene arctic paleoclimate record from Colville River delta sediments.

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, Kathryn Melissa; Lowry, Thomas Stephen

    2013-10-01

    This work was partially supported by the Sandia National Laboratories, Laboratory Directed Research and Development (LDRD) fellowship program in conjunction with Texas A&M University (TAMU). The research described herein is the work of Kathryn M. Schreiner (Katie) and her advisor, Thomas S. Bianchi and represents a concise description of Katies dissertation that was submitted to the TAMU Office of Graduate Studies in May 2013 in partial fulfillment of her doctorate of philosophy degree. High Arctic permafrost soils contain a massive amount of organic carbon, accounting for twice as much carbon as what is currently stored as carbon dioxide in the atmosphere. However, with current warming trends this sink is in danger of thawing and potentially releasing large amounts of carbon as both carbon dioxide and methane into the atmosphere. It is difficult to make predictions about the future of this sink without knowing how it has reacted to past temperature and climate changes. This project investigated long term, fine scale particulate organic carbon (POC) delivery by the high-Arctic Colville River into Simpsons Lagoon in the near-shore Beaufort Sea. Modern POC was determined to be a mixture of three sources (riverine soils, coastal erosion, and marine). Downcore POC measurements were performed in a core close to the Colville River output and a core close to intense coastal erosion. Inputs of the three major sources were found to vary throughout the last two millennia, and in the Colville River core covary significantly with Alaskan temperature reconstructions.

  9. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer

  10. Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer

  11. Screening and Characterization of Cold-Active β-Galactosidase Producing Psychrotrophic Enterobacter ludwigii from the Sediments of Arctic Fjord.

    Science.gov (United States)

    Alikkunju, Aneesa P; Sainjan, Neethu; Silvester, Reshma; Joseph, Ajith; Rahiman, Mujeeb; Antony, Ally C; Kumaran, Radhakrishnan C; Hatha, Mohamed

    2016-10-01

    Low-temperature-tolerant microorganisms and their cold-active enzymes could be an innovative and invaluable tool in various industrial applications. In the present study, bacterial isolates from the sediment samples of Kongsfjord, Norwegian Arctic, were screened for β-galactosidase production. Among the isolates, KS25, KS85, KS60, and KS92 have shown good potential in β-galactosidase production at 20 °C. 16SrRNA gene sequence analysis revealed the relatedness of the isolates to Enterobacter ludwigii. The optimum growth temperature of the isolate was 25 °C. The isolate exhibited good growth and enzyme production at a temperature range of 15-35 °C, pH 5-10. The isolate preferred yeast extract and lactose for the maximum growth and enzyme production at conditions of pH 7.0, temperature of 25 °C, and agitation speed of 100 rpm. The growth and enzyme production was stimulated by Mn 2+ and Mg 2+ and strongly inhibited by Zn 2+ , Ni 2+ , and Cu + . β-Galactosidases with high specific activity at low temperatures are very beneficial in food industry to compensate the nutritional problem associated with lactose intolerance. The isolate exhibited a remarkable capability to utilize clarified whey, an industrial pollutant, for good biomass and enzyme yield and hence could be well employed in whey bioremediation.

  12. Carbonaceous particle record in lake sediments from the Arctic and other remote areas of the northern hemisphere

    International Nuclear Information System (INIS)

    Rose, N.L.

    1995-01-01

    Lake sediments, including spheroidal carbonaceous particles produced by high temperature combustion of fossil fuels, contain a record of lake, catchment and atmospheric deposition history. The spatial and temporal distributions of these particles can indicate the extent to which a single lake or a region has been contaminated by airborne pollutants (e.g. sulfur, polycyclic aromatic hydrocarbons (PAHs)) derived from fossil fuels. The carbonaceous particle records of two Arctic lakes, Shuonijavr and Stepanovichjarvi, close to local pollution sources on the Kola Peninsula, Russia, are compared with the record of a remote lake on Svalbard and with mid-latitude remote mountain lakes in Europe and Asia. Although, Shuonijavr and Stepanovichjarvi show relatively high levels of contamination, as expected, the presence of carbonaceous particles at all of the remote sites studied suggests there is a hemispherical background of these particles. Other less remote mountain lakes in Europe have been found to contain significant concentrations of particles and these may represent regional deposition patterns. Carbonaceous particle analysis may provide an effective assessment of whether a lake site is receiving local, regional or background levels of deposition

  13. Nitrogen fixation in arctic marine sediments: effect of oil and hydrocarbon fractions

    Energy Technology Data Exchange (ETDEWEB)

    Knowles, R; Wishart, C

    1977-06-01

    Nitrogen fixation (acetylene reduction) was measured in grab and core samples of sediments from the Beaufort Sea and Eskimo Lakes, Northwest Territories, Canada. Very low rates (about 25 mg N/m/sup 2/.year) were detected in untreated sediments. Activity was markedly stimulated by the addition of glucose, sucrose, lactose, mannitol and malate but much less so by acetate; negligible activity was supported by N-acetylglucosamine. There was no consistent effect of the presence or absence of oxygen. Nitrogen fixation potentials in glucose-supplemented sediment samples showed large variation between stations, between samples from the same station and between depths within single cores down to 18 cm. Weathered Normal Wells crude oil, hexane, decane, dodecane and hexadecane had no effect, stimulatory or inhibitory, on nitrogen fixation or carbon dioxide evolution. 1,2,4-trimethylbenzene caused complete inhibition of nitrogen fixation but only partial inhibition of CO/sub 2/ evolution. There was no evidence of utilization of any of the hydrocarbons tested during periods of over 30 days under the experimental conditions employed.

  14. Distribution of PAHs and the PAH-degrading bacteria in the deep-sea sediments of the high-latitude Arctic Ocean

    Science.gov (United States)

    Dong, C.; Bai, X.; Sheng, H.; Jiao, L.; Zhou, H.; Shao, Z.

    2015-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are common organic pollutants that can be transferred long distances and tend to accumulate in marine sediments. However, less is known regarding the distribution of PAHs and their natural bioattenuation in the open sea, especially the Arctic Ocean. In this report, sediment samples were collected at four sites from the Chukchi Plateau to the Makarov Basin in the summer of 2010. PAH compositions and total concentrations were examined with GC-MS. The concentrations of 16 EPA-priority PAHs varied from 2.0 to 41.6 ng g-1 dry weight and decreased with sediment depth and movement from the southern to the northern sites. Among the targeted PAHs, phenanthrene was relatively abundant in all sediments. The 16S rRNA gene of the total environmental DNA was analyzed with Illumina high-throughput sequencing (IHTS) to determine the diversity of bacteria involved in PAH degradation in situ. The potential degraders including Cycloclasticus, Pseudomonas, Halomonas, Pseudoalteromonas, Marinomonas, Bacillus, Dietzia, Colwellia, Acinetobacter, Alcanivorax, Salinisphaera and Shewanella, with Dietzia as the most abundant, occurred in all sediment samples. Meanwhile, enrichment with PAHs was initiated onboard and transferred to the laboratory for further enrichment and to obtain the degrading consortia. Most of the abovementioned bacteria in addition to Hahella, Oleispira, Oceanobacter and Hyphomonas occurred alternately as predominant members in the enrichment cultures from different sediments based on IHTS and PCR-DGGE analysis. To reconfirm their role in PAH degradation, 40 different bacteria were isolated and characterized, among which Cycloclasticus Pseudomonas showed the best degradation capability under low temperatures. Taken together, PAHs and PAH-degrading bacteria were widespread in the deep-sea sediments of the Arctic Ocean. We propose that bacteria of Cycloclasticus, Pseudomonas, Pseudoalteromonas, Halomonas, Marinomonas and Dietzia may

  15. Preliminary Results on Mineralogy and Geochemistry of Loki's Castle Arctic Vents and Host Sediments

    Science.gov (United States)

    Barriga, Fernando; Carvalho, Carlos; Inês Cruz, M.; Dias, Ágata; Fonseca, Rita; Relvas, Jorge; Pedersen, Rolf

    2010-05-01

    The Loki's Castle hydrothermal vent field was discovered in the summer of 2008, during a cruise led by the Centre of Geobiology of the University of Bergen, integrated in the H2Deep Project (Eurocores, ESF). Loki's Castle is the northernmost hydrothermal vent field discovered to date. It is located at the junction between the Mohns Ridge and the South Knipovich Ridge, in the Norwegian-Greenland Sea, at almost 74°N. This junction shows unique features and apparently there is no transform fault to accommodate the deformation generated by the bending of the rift valley from WSW-ENE to almost N-S. The Knipovich Rigde, being a complex structure, is an ultra-slow spreading ridge, with an effective spreading rate of only ~ 6 mm/y. It is partly masked by a substantial cover of glacial and post-glacial sediments, estimated to be between 12 and 20 ky old, derived from the nearby Bear Island fan, to the East of the ridge. The Loki's Castle vent site is composed of several active, over 10 m tall chimneys, producing up to 320°C fluid, at the top of a very large sulphide mound, which is estimated to be around 200 m in diameter. About a dozen gravity cores were obtained in the overall area. From these we collected nearly 200 subsamples. Eh and pH were measured in all subsamples. The Portuguese component of the H2Deep project is aimed at characterizing, chemically and mineralogically, the sulphide chimneys and the collected sediments around the vents (up to 5 meters long gravity cores). These studies are aimed at understanding the ore-forming system, and its implications for submarine mineral exploration, as well as the relation of the microbial population with the hydrothermal component of sediments. Here we present an overview of preliminary data on the mineralogical assemblage found in the analyzed sediments and chimneys. The identification of the different mineral phases was obtained through petrographic observations of polished thin sections under the microscope (with both

  16. Monitoring of Hydrocarbons in Sediment and Biota Related to Oil and Gas Development in Near- and Off-Shore Areas of the Arctic Beaufort Sea, Alaska

    Science.gov (United States)

    Durell, G.; Hardin, J.; Libby, S.

    2016-02-01

    There is increasing interest in extracting oil and gas from offshore environments of Alaska. The Arctic Nearshore Impact Monitoring in Development Area (ANIMIDA) project, started in 1999, has been producing information to evaluate potential effects of oil and gas activities in the Alaskan Beaufort Sea. ANIMIDA was preceded by the Beaufort Sea Monitoring Program. Monitoring has mostly been in pre-drilling locations, but also during development and production periods. Surveys were conducted to assess bottom sediment, sediment cores, suspended sediment, and biota for polycyclic aromatic hydrocarbons (PAH), saturated hydrocarbons, biological and petroleum markers, and geophysical parameters. The concentrations measured in sediments and biota were at or near background throughout most of the Beaufort Sea. There were no significant differences between exploration, production, and background locations, and the concentrations were consistently below those of ecological concern. For instance, TPAH in sediment ranged from below 100 to about 1,000 µg/kg and were controlled primarily by sediment characteristics (e.g., grain size and organic carbon). Hydrocarbons in sediments were from petrogenic, pyrogenic, and biogenic sources. Small areas with indications of input of anthropogenic chemicals were identified by sensitive diagnostic analysis techniques and are possibly associated with historic exploratory drilling and vessels. Sediment cores indicate a uniform historical deposition of hydrocarbons, although some evidence of past drilling activities were observed. Fish, amphipods, and clams contained background levels of hydrocarbons and showed no evidence of effects from accumulation of contaminants; TPAH concentrations were below 100 µg/kg in most biota. Noteworthy interannual fluctuations were observed for PAH concentrations in sediment and biota, likely due to winnowing of sediment fines by large storms and annual variations in river discharges. Significant natural sources

  17. Sea ice and primary production proxies in surface sediments from a High Arctic Greenland fjord

    DEFF Research Database (Denmark)

    Ribeiro, Sofia; Sejr, Mikael K; Limoges, Audrey

    2017-01-01

    Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP25 was detected at all sites but at low concentrations, indicating...... that IP25 records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable......In order to establish a baseline for proxy-based reconstructions for the Young Sound–Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem...

  18. Lignocellulose mineralization by Arctic lake sediments in response to nutrient manipulation

    International Nuclear Information System (INIS)

    Federle, T.W.; Vestal, J.R.

    1980-01-01

    Mineralization of specifically labeled 14 C-cellulose- and 14 C-lignin-labeled lignocelluloses by Toolik Lake, Alaska, sediments was examined in response to manipulation of various environmental factors. Mineralization was measured by quantifying the amount of labeled CO 2 released from the specifically labeled substrates. Nitrogen (NH 4 NO 3 ) and, to a greater degree, phosphorus (PO 4 -3 ) additions enhanced the mineralization of white pine (Pinus strobus) cellulose during the summer of 1978. Nitrogen and phosphorus together had no cumulative effect. During the summer of 1979, nitrogen or phosphorus alone had only a slight stimulatory effect on the mineralization of a sedge (Carex aquatilis) cellulose; however, together, they had a dramatic effect. This variable response of mineralization to nutrient addition between 1978 and 1979 was probably attributable to year-to-year variation in nutrient availability within the lake. Cellobiose addition and oxygen depletion inhibited the amount of pine cellulose mineralized. Whereas addition of nitrogen to oxygen-depleted treatments had limited effect, addition of phosphorus resulted in mineralizations equal to or greater than that of the controls. Nitrogen had no effect on mineralization of pine or Carex lignins. Phosphorus, however, inhibited mineralization of both lignins. With Carex lignin, the phosphorus inhibition occurred at a concentration as low as 0.1 μM. The antagonistic role of phosphorus in cellulose and lignin mineralizations may be of significance in understanding the increased proportion of lignin relative to cellulose in decomposing litter

  19. Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

    DEFF Research Database (Denmark)

    Knoblauch, C.; Jørgensen, BB

    1999-01-01

    Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields...... at in site conditions....

  20. 210Po/210Pb Activity Ratios as a Possible `Dating Tool' of Ice Cores and Ice-rafted Sediments from the Western Arctic Ocean - Preliminary Results

    Science.gov (United States)

    Krupp, K.; Baskaran, M. M.

    2016-02-01

    We have collected and analyzed a suite of surface snow samples, ice cores, ice-rafted sediments (IRS) and aerosol samples from the Western Arctic for Po-210 and Pb-210 to examine the extent of disequilibrium between this pair to possibly use 210Po/210Pb activity ratio to date different layers of ice cores and time of incorporation of ice-rafted sediments into the sea ice. We have earlier reported that the activity concentrations of 210Pb in IRS vary over an order of magnitude and it is 1-2 orders of magnitude higher than that of the benthic sediments (1-2 dpm/g in benthic sediments compared to 25 to 300 dpm/g in IRS). In this study, we have measured 210Po/210Pb activity ratios in aerosols from the Arctic Ocean to constrain the initial 210Po/210Pb ratio at the time of deposition during precipitation. The 210Po activity concentration in recent snow is compared to surface ice samples. The `age' of IRS incorporation can be calculated as follows: [210Po]measured = [210Po]initial + [210Pb] (1 - exp(-λt)) (1) where λ is the decay constant of 210Po, 138.4 days, and `t' is the in-growth time period. From this equation, `t' can be calculated as follows: t = (-1/λ) [ln (1- ((210Po/210Pb)measured - (210Po/210Pb)initial)] (2) The assumption involved in this approach are: i) there is no preferential uptake of 210Po (highly biogenic - S group); and iii) both 210Po and 210Pb remain as closed system. The calculated age using equation (2) will be discussed and presented.

  1. Regional patterns of labile organic carbon flux in North American Arctic Margin (NAAM) as reflected by redox sensitive-elements distributions in sediments

    Science.gov (United States)

    Gobeil, C.; Kuzyk, Z. Z. A.; Goni, M. A.; Macdonald, R. W.

    2016-02-01

    Concentrations of elements (S, Mn, Mo, U, Cd, Re) providing insights on organic C metabolized through oxidative processes at the sea floor were measured in 27 sediment cores collected along a section extending from the North Bering Sea to Davis Strait via the Canadian Archipelago. Sedimentary distributions and accumulation rates of these elements were used to i) document the relative importance of aerobic versus anaerobic degradation of organic C in NAAM sediments, ii) infer variations in water column carbon flux and iii) estimate the importance of this margin as a sink for key elements in the Arctic and global ocean. Distributions of Mn, total S and reduced inorganic S demonstrated that most sediments along the NAAM had relatively thick (>1 cm) surface oxic layers, underlain by sediments with weakly reducing conditions and limited sulphate reduction. Strongly reducing conditions accompanied by substantial sedimentary pyrite burial occurred only in certain subregions, including the Bering-Chukchi Shelves, shallow portions of Barrow Canyon. Estimated accumulation rates of authigenic S, Mo, Cd and U, and total Re displayed marked spatial variability that was related to sedimentary redox conditions induced by the supply of labile C to the seabed, as shown by significant relationships between the accumulation rates and vertical C flux, estimated from regional primary production values and water depth at the coring sites. High primary production combined with shallow water columns drive elevated rates of authigenic trace element accumulation in sediments from the Bering-Chukchi Shelves whereas low production combined with moderately deep conditions drive low rates of accumulation in sediments in the Beaufort Shelf, Davis Strait and Canadian Archipelago. Using the average authigenic trace element accumulation rates in sediments from the various regions, we submit that the shelves along the NAAM margin are important sinks in global marine biogeochemical budgets.

  2. High-resolution sub-bottom seismic and sediment core records from the Chukchi Abyssal Plain reveal Quaternary glaciation impacts on the western Arctic Ocean

    Science.gov (United States)

    Joe, Y. J.; Seokhoon, Y.; Nam, S. I.; Polyak, L.; Niessen, F.

    2017-12-01

    For regional context of the Quaternary history of Arctic marine glaciations, such as glacial events in northern North America and on the Siberian and Chukchi margins, we used CHIRP sub-bottom profiles (SBP) along with sediment cores, including a 14-m long piston core ARA06-04JPC taken from the Chukchi abyssal plain during the RV Araon expedition in 2015. Based on core correlation with earlier developed Arctic Ocean stratigraphies using distribution of various sedimentary proxies, core 04JPC is estimated to extend to at least Marine Isotope Stage 13 (>0.5 Ma). The stratigraphy developed for SBP lines from the Chukchi abyssal plain to surrounding slopes can be divided into four major seismostratigraphic units (SSU 1-4). SBP records from the abyssal plain show well preserved stratification, whereas on the surrounding slopes this pattern is disrupted by lens-shaped, acoustically transparent sedimentary bodies interpreted as glaciogenic debris flow deposits. Based on the integration of sediment physical property and SBP data, we conclude that these debris flows were generated during several ice-sheet grounding events on the Chukchi and East Siberian margins, including adjacent ridges and plateaus, during the middle to late Quaternary.

  3. Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores

    International Nuclear Information System (INIS)

    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.

    2005-01-01

    Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210 Pb and 137 Cs, 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

  4. The freshwater fern Azolla (Azollaceae) from Eocene Arctic and Nordic Sea sediments: New species and their stratigraphic distribution

    NARCIS (Netherlands)

    van der Burgh, J.; Collinson, M.E.; van Konijnenburg-van Cittert, J.H.A.; Barke, J.; Brinkhuis, H.

    2013-01-01

    Three new species of the freshwater fern Azolla are described from Eocene marine deposits of the Arctic and Nordic seas, bringing the total number of species now documented from these areas to five. Azolla arctica Collinson et al., Azolla jutlandica Collinson et al., Azolla nova sp. nov. and Azolla

  5. Late Eocene to present isotopic (Sr-Nd-Pb) and geochemical evolution of sediments from the Lomonosov Ridge, Arctic Ocean: Implications for continental sources and linkage with the North Atlantic Ocean

    Science.gov (United States)

    Stevenson, Ross; Poirier, André; Véron, Alain; Carignan, Jean; Hillaire-Marcel, Claude

    2015-09-01

    New geochemical and isotopic (Sr, Nd, Pb) data are presented for a composite sedimentary record encompassing the past 50 Ma of history of sedimentation on the Lomonosov Ridge in the Arctic Ocean. The sampled sediments encompass the transition of the Arctic basin from an enclosed anoxic basin to an open and ventilated oxidized ocean basin. The transition from anoxic basin to open ventilated ocean is accompanied by at least three geochemical and isotopic shifts and an increase in elements (e.g., K/Al) controlled by detrital minerals highlighting significant changes in sediment types and sources. The isotopic compositions of the sediments prior to ventilation are more variable but indicate a predominance of older crustal contributions consistent with sources from the Canadian Shield. Following ventilation, the isotopic compositions are more stable and indicate an increased contribution from younger material consistent with Eurasian and Pan-African crustal sources. The waxing and waning of these sources in conjunction with the passage of water through Fram Strait underlines the importance of the exchange of water mass between the Arctic and North Atlantic Oceans.

  6. Sedimentation

    Science.gov (United States)

    Cliff R. Hupp; Michael R. Schening

    2000-01-01

    Sedimentation is arguably the most important water-quality concern in the United States. Sediment trapping is cited frequently as a major function of riverine-forested wetlands, yet little is known about sedimcntation rates at the landscape scale in relation to site parameters, including woody vegetation type, elevation, velocity, and hydraulic connection to the river...

  7. The PLOT (Paleolimnological Transect) Project in the Russian Arctic

    Science.gov (United States)

    Gromig, R.; Andreev, A.; Baumer, M.; Bolshiyanov, D.; Fedorov, G.; Frolova, L.; Krastel, S.; Lebas, E.; Ludikova, A.; Melles, M.; Meyer, H.; Nazarova, L.; Pestryakova, L.; Savelieva, L.; Shumilovskikh, L.; Subetto, D.; Wagner, B.; Wennrich, V.

    2017-12-01

    The joint Russian- German project 'PLOT - Paleolimnological Transec' aims to recover lake sediment sequences along a >6000 km long longitudinal transect across the Eurasian Arctic in order to investigate the Late Quaternary climatic and environmental history. The climate history of the Arctic is of particular interest since it is the region, which is experiencing major impact of the current climate change. The project is funded for three years (2015-2018) by the Russian and German Ministries of Research. Since 2013 extensive fieldwork, including seismic surveys, coring, and hydrological investigations, was carried out at lakes Ladoga (NW Russia, pilot study), Bolshoye Shuchye (Polar Urals), Emanda (Verkhoyansk Range, field campaign planned for August 2017), Levinson-Lessing and Taymyr (Taymyr Peninsula). Fieldwork at lakes Bolshoye Shuchye, Levinson-Lessing and Taymyr was conducted in collaboration with the Russian-Norwegian CHASE (Climate History along the Arctic Seaboard of Eurasia) project. A major objective of the PLOT project was to recover preglacial sediments. A multiproxy approach was applied to the analytical work of all cores, including (bio-)geochemical, sedimentological, geophysical, and biological analyses. First data implies the presence of preglacial sediments in the cores from all lakes so far visited. Age-depth models, based on radiocarbon dating, OSL dating, paleomagnetic measurements, identification of cryptotephra, and varve counting (where applicable), are in progress. Climate variability in the records shall be compared to that recorded at Lake Eĺgygytgyn (NE Russia), which represents the master record for the Siberian Arctic. The outcome of the PLOT project will be a better understanding of the temporal and spatial variability and development of the Arctic climate. Here, we present the major results and first key interpretations of the PLOT project, along with an outlook on the future strategy and foci. First results from lakes Ladoga

  8. Iceberg and meltwater discharge events in the western Arctic Ocean since MIS 5: a comparison of sediment cores off the East Siberian and Chukchi margins

    Science.gov (United States)

    Xiao, W.; Wang, R.; Zhang, T.; Duan, X.; Polyak, L.

    2017-12-01

    In the Pleistocene the western Arctic Ocean was affected by deglacial discharge events from ice sheets in northern North America as well as the East Siberian and Chukchi margins. Distribution of Ice Rafted Debris (IRD) >250 μm and planktonic foraminiferal N. pachyderma (sin.) (Nps) δ18O and δ13C was compared in CHINARE sediment cores ARC2-M03 (Wang et al., 2013) and ARC3-P37 from the Chukchi Abyssal Plain and Northwind Ridge, respectively, to identify the impacts of icebergs and meltwater on paleoceanographic environments since MIS 5. The IRD is mainly composed of quartz grains and fragments of clastic rocks and detrital carbonates. The carbonates, mostly dolomites characteristic of the Canadian Arctic Archipelago (CAA) provenance, typically anti-correlate with quartz and clastic rocks, indicating different sources such as Chukchi-Alaskan or East Siberian margin. Most of the Nps δ18O depletions correspond to peaks in detrital carbonates, suggesting a strong influence of meltwater from the Laurentide Ice Sheet (LIS) on the western Arctic Ocean. A conspicuous dark gray interval interpreted to represent glacial/deglacial environments of MIS 4/3 age, shows a remarkable depletion in Nps δ13C along with high δ18O values and absence of IRD. This unusual signature may be related to a persistent sea-ice cover and/or high fluxes of terrigenous material with deglacial debris flows. In a younger grey interval corresponding to MIS2, high abundances of quartz and clastic rocks in the Northwind Ridge core ARC3-P37 indicate iceberg discharge from areas other than CAA, such as the Mackenzie LIS lobe or Chukchi-Alaskan margin. The MIS2-Holocene transition is marked by an increase in detrital carbonates co-occurring with Nps δ13C and δ18O depletion (Polyak et al., 2007), indicative of LIS iceberg/meltwater fluxes from the CAA. We note that stable-isotope events in the study area may go unnoticed because of gaps in foraminiferal records related to dissolution and/or adverse

  9. Biomonitoring polluted sediments in Arctic regions - possibilities and challenges using benthic foraminifera. Case studies from northern Norway

    Science.gov (United States)

    Skirbekk, Kari; Dijkstra, Noortje; Junttila, Juho; Sternal, Beata; Pedersen, Kristine Bondo; Forwick, Matthias; Carroll, JoLynn

    2016-04-01

    Biomonitoring pollution in marine environments using benthic foraminifera assemblages have proven to be a valid method for many regions. Two important reasons for their suitability are their sensitivity to changes in the environment and their rapid response time due to short life cycles. In addition, they are preserved in the sedimentary record, allowing for baseline studies of conditions prior to introduction of contaminants. Species of benthic foraminifera that appear to tolerate polluted sediments are referred to as opportunistic species. This notion is in general used for species able to dominate environments that are too stressful for most species. The high latitude setting of the northern Norwegian coastal zone experience high seasonality and, hence, largely changing conditions throughout a year: variations in water mass domination, freshwater influence, temperature and current velocity. It is possible that an environment like this is inhibited by a higher amount of opportunistic species generally thriving under high stress conditions. This might make the use of benthic foraminifera for biomonitoring more challenging, as the faunal compositions may be a result of a complex set of processes. Consequently, large datasets are necessary in order to make reliable conclusions, which in time may be used as generalized guidelines for biomonitoring in this geographical area. Here, we present preliminary results of benthic foraminiferal assemblages from two sites in Finnmark, northern Norway, which have been exposed to pollution. The main site is Repparfjorden, where the inner parts of the fjord were used as a submarine waste deposal site for mine tailings from a local copper mine during the 1970´s. Results from four marine sediment cores (10-20 cm long) containing sediments classified to be in moderate to very bad state (according to Norwegian sediment quality criteria) are presented. The contamination is seen in intervals of elevated copper content dated to the 1970

  10. Process-diagnostic patterns of chlorobiphenyl congeners in two radiochronologically characterized sediment cores from the northern Baffin Bay

    DEFF Research Database (Denmark)

    Gustafsson, O.; Axelman, J.; Broman, D.

    2001-01-01

    that the PCB distribution in Arctic surface sediments is governed by the organic carbon (OC) content of the sediments. The historical development of the PCB congener fingerprint suggests that the modern sediments are enriched in medium-chlorinated congeners, implying that there are at least two significant......, but distinctly different, sink processes acting on the PCB pool. The relative abundance of light-to-heavy congeners, in mid-shelf marine sediments of similar ages, between 40 degreesN and 76 degreesN latitude suggests a northward dilution of PCBs which is stronger attenuated for heavier congeners, consistent...

  11. Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

    DEFF Research Database (Denmark)

    Knoblauch, C.; Jørgensen, BB

    1999-01-01

    and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields......Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... for growth (T(opt)) were 7 degrees C (PSv29), 10 degrees C (ASv26, LSv54) and 18 degrees C (LSv21, LSv514), Although T(opt) was considerably above the in situ temperatures of their habitats (-1.7 degrees C and 2.6 degrees C), relative growth rates were still high at 0 degrees C, accounting for 25...

  12. Petrophysical characterization of the lacustrine sediment succession drilled in Lake El'gygytgyn, Far East Russian Arctic

    Directory of Open Access Journals (Sweden)

    A. C. Gebhardt

    2013-08-01

    Full Text Available Seismic profiles of Far East Russian Lake El'gygytgyn, formed by a meteorite impact some 3.6 million years ago, show a stratified sediment succession that can be separated into subunits Ia and Ib at approximately 167 m below lake floor (=~3.17 Ma. The upper (Ia is well-stratified, while the lower is acoustically more massive and discontinuous. The sediments are intercalated with frequent mass movement deposits mainly in the proximal areas, while the distal region is almost free of such deposits at least in the upper part. In spring 2009, a long core drilled in the lake center within the framework of the International Continental Scientific Drilling Program (ICDP penetrated the entire lacustrine sediment succession down to ~320 m below lake floor and about 200 m farther into the meteorite-impact-related bedrock. Downhole logging data down to 390 m below lake floor show that the bedrock and the lacustrine part differ significantly in their petrophysical characteristics. The contact between the bedrock and the lacustrine sediments is not abrupt, but rather transitional with a variable mixture of impact-altered bedrock clasts in a lacustrine matrix. Physical and chemical proxies measured on the cores can be used to divide the lacustrine part into five different statistical clusters. These can be plotted in a redox-condition vs. input-type diagram, with total organic carbon content and magnetic susceptibility values indicating anoxic or oxic conditions and with the Si / Ti ratio representing more clastic or more biogenic input. Plotting the clusters in this diagram allows identifying clusters that represent glacial phases (cluster I, super interglacials (cluster II, and interglacial phases (clusters III and IV.

  13. Arctic Ocean circulation during the anoxic Eocene Azolla event

    Science.gov (United States)

    Speelman, Eveline; Sinninghe Damsté, Jaap; März, Christian; Brumsack, Hans; Reichart, Gert-Jan

    2010-05-01

    The Azolla interval, as encountered in Eocene sediments from the Arctic Ocean, is characterized by organic rich sediments ( 4wt% Corg). In general, high levels of organic matter may be caused by increased productivity, i.e. extensive growth of Azolla, and/or enhanced preservation of organic matter, or a combination of both. Anoxic (bottom) water conditions, expanded oxygen minimum zones, or increased sedimentation rates all potentially increase organic matter preservation. According to plate tectonic, bathymetric, and paleogeographic reconstructions, the Arctic Ocean was a virtually isolated shallow basin, with one possible deeper connection to the Nordic Seas represented by a still shallow Fram Strait (Jakobsson et al., 2007), hampering ventilation of the Arctic Basin. During the Azolla interval surface waters freshened, while at the same time bottom waters appear to have remained saline, indicating that the Arctic was highly stratified. The restricted ventilation and stratification in concert with ongoing export of organic matter most likely resulted in the development of anoxic conditions in the lower part of the water column. Whereas the excess precipitation over evaporation maintained the freshwater lid, sustained input of Nordic Sea water is needed to keep the deeper waters saline. To which degree the Arctic Ocean exchanged with the Nordic Seas is, however, still largely unknown. Here we present a high-resolution trace metal record (ICP-MS and ICP-OES) for the expanded Early/Middle Eocene section capturing the Azolla interval from Integrated Ocean Drilling Program (IODP) Expedition 302 (ACEX) drilled on the Lomonosov Ridge, central Arctic Ocean. Euxinic conditions throughout the interval resulted in the efficient removal of redox sensitive trace metals from the water column. Using the sedimentary trace metal record we also constrained circulation in the Arctic Ocean by assessing the relative importance of trace metal input sources (i.e. fluvial, eolian, and

  14. Option-implied term structures

    OpenAIRE

    Vogt, Erik

    2014-01-01

    The illiquidity of long-maturity options has made it difficult to study the term structures of option spanning portfolios. This paper proposes a new estimation and inference framework for these option-implied term structures that addresses long-maturity illiquidity. By building a sieve estimator around the risk-neutral valuation equation, the framework theoretically justifies (fat-tailed) extrapolations beyond truncated strikes and between observed maturities while remaining nonparametric. Ne...

  15. Arctic Newcomers

    DEFF Research Database (Denmark)

    Tonami, Aki

    2013-01-01

    Interest in the Arctic region and its economic potential in Japan, South Korea and Singapore was slow to develop but is now rapidly growing. All three countries have in recent years accelerated their engagement with Arctic states, laying the institutional frameworks needed to better understand...... and influence policies relating to the Arctic. But each country’s approach is quite different, writes Aki Tonami....

  16. Severnaya Zemlya, arctic Russia: a nucleation area for Kara Sea ice sheets during the Middle to Late Quaternary

    DEFF Research Database (Denmark)

    Möller, Per; Lubinski, David J.; Ingólfsson, Ólafur

    2006-01-01

    Quaternary glacial stratigraphy and relative sea-level changes reveal at least four expansions of the Kara Sea ice sheet over the Severnaya Zemlya Archipelago at 79°N in the Russian Arctic, as indicated from tills interbedded with marine sediments, exposed in stratigraphic superposition, and from......-5e and MIS 5d-3. The MIS 6-5e event, associated with the high marine limit, implies ice-sheet thickness of >2000 m only 200 km from the deep Arctic Ocean, consistent with published evidence of ice grounding at ~1000 m water depth in the central Arctic Ocean. Till fabrics and glacial tectonics record...... repeated expansions of local ice caps exclusively, suggesting wet-based ice cap advance followed by cold-based regional ice-sheet expansion. Local ice caps over highland sites along the perimeter of the shallow Kara Sea, including the Byrranga Mountains, appear to have repeatedly fostered initiation...

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

    Science.gov (United States)

    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

  18. Methane from the East Siberian Arctic shelf

    DEFF Research Database (Denmark)

    Petrenko...[], Vasilii V.; Etheridge, David M.

    2010-01-01

    In their Report “Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf” (5 March, p. 1246), N. Shakhova et al. write that methane (CH4) release resulting from thawing Arctic permafrost “is a likely positive feedback to climate warming.” They add...

  19. IMPLIED AUTHOR IN PHILOSOPHICAL NOVELS

    Directory of Open Access Journals (Sweden)

    Olga Senkāne

    2014-10-01

    Full Text Available The present article falls within a number of papers about research on specification of philosophical novels. The aim of this article is to analyze author’s function as a narrative category in classical philosophical novels (Franz Kafka "The Trial" (1925, "The Castle" (1926, Jean-Paul Sartre "Nausea" (1938, Hermann Hesse "The Glass Bead Game" (1943, Albert Camus "The Plague" (1947 and a novel of Latvian prose writer Ilze Šķipsna "Neapsolītās zemes" ["Un-Promised Lands"] (1970. The analysis is based on theoretical ideas of structural narratologists Gerard Genette, William Labov, Seymuor Chatman, Wolf Schmid, as well as philosophers Edmund Husserl, Jean-Paul Sartre, Paul Ricouer and semioticians Yuri Lotman (Юрий Лотман and Umberto Eco. The real author can ”enter” the text only indirectly—as an image, with the help of the storyteller, and the way how this ”entry” happens is determined by the narration of the real author or narrative (communication skills of the author. Thus, the author and implied author are functionally different concepts: author as a real person develops the concept idea, his intention is to define the concept under his original vision; narrator, in its turn, communicates with the reader, representing the concept, and his aim is to select appropriate means of communication with regard to reader’s perceptual abilities.

  20. Arctic Security

    DEFF Research Database (Denmark)

    Wang, Nils

    2013-01-01

    The inclusion of China, India, Japan, Singapore and Italy as permanent observers in the Arctic Council has increased the international status of this forum significantly. This chapter aims to explain the background for the increased international interest in the Arctic region through an analysis...

  1. Tsunami in the Arctic

    Science.gov (United States)

    Kulikov, Evgueni; Medvedev, Igor; Ivaschenko, Alexey

    2017-04-01

    rate of 10-3 per year. Additional tsunami threat might arise from rare earthquake occurrences within the continental slope of deep-sea basin of the Arctic Ocean and near the coast of the continent, where high probability of triggering submarine landslides exists that can generate even more dangerous tsunamis than those of seismotectonic origin. The most reliable information about the manifestation of the tsunami in the Arctic is associated with submarine landslide Storegga located on the continental slope of the Norwegian Sea and collapsed 8,200 years ago. Traces of sediment left behind by the tsunami waves on the coast, show that the maximum vertical tsunami runup could reach 20 meters. Factors causing the potential tsunami thread of landslides in Russian Arctic are sedimentation processes that can be associated with the formation of the alluvial fans of the great Siberian rivers Ob, Yenisei and Lena.

  2. Severnaya Zemlya, arctic Russia: a nucleation area for Kara Sea ice sheets during the Middle to Late Quaternary

    DEFF Research Database (Denmark)

    Möller, Per; Lubinski, David J.; Ingólfsson, Ólafur

    2006-01-01

    Quaternary glacial stratigraphy and relative sea-level changes reveal at least four expansions of the Kara Sea ice sheet over the Severnaya Zemlya Archipelago at 79°N in the Russian Arctic, as indicated from tills interbedded with marine sediments, exposed in stratigraphic superposition, and from...... of a large Kara Sea ice sheet, with exception of the Last Glacial Maximum (MIS 2), when Kara Sea ice did not impact Severnaya Zemlya and barely graced northernmost Taymyr Peninsula.......Quaternary glacial stratigraphy and relative sea-level changes reveal at least four expansions of the Kara Sea ice sheet over the Severnaya Zemlya Archipelago at 79°N in the Russian Arctic, as indicated from tills interbedded with marine sediments, exposed in stratigraphic superposition, and from......-5e and MIS 5d-3. The MIS 6-5e event, associated with the high marine limit, implies ice-sheet thickness of >2000 m only 200 km from the deep Arctic Ocean, consistent with published evidence of ice grounding at ~1000 m water depth in the central Arctic Ocean. Till fabrics and glacial tectonics record...

  3. 32 CFR 634.8 - Implied consent.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Implied consent. 634.8 Section 634.8 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) LAW ENFORCEMENT AND CRIMINAL INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Privileges § 634.8 Implied consent. (a) Implied consent to blood, breath, or urine tests....

  4. Forecasting with Option-Implied Information

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Chang, Bo Young

    2013-01-01

    This chapter surveys the methods available for extracting information from option prices that can be used in forecasting. We consider option-implied volatilities, skewness, kurtosis, and densities. More generally, we discuss how any forecasting object that is a twice differentiable function...... of the future realization of the underlying risky asset price can utilize option-implied information in a well-defined manner. Going beyond the univariate option-implied density, we also consider results on option-implied covariance, correlation and beta forecasting, as well as the use of option......-implied information in cross-sectional forecasting of equity returns. We discuss how option-implied information can be adjusted for risk premia to remove biases in forecasting regressions....

  5. Politics of sustainability in the Arctic (POSUSA)

    DEFF Research Database (Denmark)

    Gad, Ulrik Pram; Jakobsen, Uffe; Strandsbjerg, Jeppe

    The concept of sustainability is of central importance in Arctic politics. However, for different actors (governments, indigenious peoples, NGOs) the concept implies different sets of precautions and opportunities. Sustainability, therefore, is much more a fundamental concept to be further...... elaborated than a definable term with a specific meaning. This is the core hypothesis in a collective research project, the POSUSA project (Politics of Sustainability in the Arctic) that aims to map and analyse the role of sustainability in various political and economic strategies in the Arctic....

  6. The Arctic

    International Nuclear Information System (INIS)

    Petersen, H.; Meltofte, H.; Rysgaard, S.; Rasch, M.; Jonasson, S.; Christensen, T.R.; Friborg, T.; Soegaard, H.; Pedersen, S.A.

    2001-01-01

    Global climate change in the Arctic is a growing concern. Research has already documented pronounced changes, and models predict that increases in temperature from anthropogenic influences could be considerably higher than the global average. The impacts of climate change on Arctic ecosystems are complex and difficult to predict because of the many interactions within ecosystem, and between many concurrently changing environmental variables. Despite the global consequences of change in the Arctic climate the monitoring of basic abiotic as well as biotic parameters are not adequate to assess the impact of global climate change. The uneven geographical location of present monitoring stations in the Arctic limits the ability to understand the climate system. The impact of previous variations and potential future changes to ecosystems is not well understood and need to be addressed. At this point, there is no consensus of scientific opinion on how much of the current changes that are due to anthropogenic influences or to natural variation. Regardless of the cause, there is a need to investigate and assess current observations and their effects to the Arctic. In this chapter examples from both terrestrial and marine ecosystems from ongoing monitoring and research projects are given. (LN)

  7. Arctic bioremediation

    International Nuclear Information System (INIS)

    Lidell, B.V.; Smallbeck, D.R.; Ramert, P.C.

    1991-01-01

    Cleanup of oil and diesel spills on gravel pads in the Arctic has typically been accomplished by utilizing a water flushing technique to remove the gross contamination or excavating the spill area and placing the material into a lined pit, or a combination of both. Enhancing the biological degradation of hydrocarbon (bioremediation) by adding nutrients to the spill area has been demonstrated to be an effective cleanup tool in more temperate locations. However, this technique has never been considered for restoration in the Arctic because the process of microbial degradation of hydrocarbon in this area is very slow. The short growing season and apparent lack of nutrients in the gravel pads were thought to be detrimental to using bioremediation to cleanup Arctic oil spills. This paper discusses the potential to utilize bioremediation as an effective method to clean up hydrocarbon spills in the northern latitudes

  8. Arctic bioremediation

    International Nuclear Information System (INIS)

    Liddell, B.V.; Smallbeck, D.R.; Ramert, P.C.

    1991-01-01

    Cleanup of oil and diesel spills on gravel pads in the Arctic has typically been accomplished by utilizing a water flushing technique to remove the gross contamination or excavating the spill area and placing the material into a lined pit, or a combination of both. This paper discusses the potential to utilize bioremediation as an effective method to clean up hydrocarbon spills in the northern latitudes. Discussed are the results of a laboratory bioremediation study which simulated microbial degradation of hydrocarbon under arctic conditions

  9. The Arctic Coastal Erosion Problem

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, Jennifer M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Matthew Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Craig A. [Integral Consulting Inc., San Francisco, CA (United States); Roberts, Jesse D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-09-01

    evolving wave dynamics, thermodynamics, and sediment dynamics must be developed. The objective of this document is to present the state-of-the-science and outline the key steps for creation of a framework that will allow for improved prediction of Arctic coastal erosion rates. This is the first step towards the quantification of coastal hazards that will allow for sustainable planning and development of Arctic infrastructure.

  10. Naval Research Laboratory Arctic Initiatives

    Science.gov (United States)

    2011-06-01

    Campaign Code 7420 Arctic Modeling Code 7320/7500/7600 In-situ NRL, CRREL NRL boreholes Strategy Remote Sensing Synergism −Collect in-situ...Navy and Marine Corps Corporate Laboratory An array of BMFCs being prepared for deployment. Each BMFC consists of a weighted anode laid flat onto...Gas CH4 E C D CO2 BGHS Free Methane Gas Hydrates HCO3- HCO3- Seismic and geochemical data to predict deep sediment hydrates Estimate spatial

  11. Implied terms in English and Romanian law

    OpenAIRE

    Stefan Dinu

    2015-01-01

    This study analyses the matter of implied terms from the point of view of both English and Romanian law. First, the introductory section provides a brief overview of implied terms, by defining this class of contractual clauses and by providing their general features. Second, the English law position is analysed, where it is generally recognised that a term may be implied in one of three manners, which are described in turn. An emp hasis is made on the Privy Council’s decision in Attorney G...

  12. Option-implied measures of equity risk

    DEFF Research Database (Denmark)

    Chang, Bo-Young; Christoffersen, Peter; Vainberg, Gregory

    2012-01-01

    Equity risk measured by beta is of great interest to both academics and practitioners. Existing estimates of beta use historical returns. Many studies have found option-implied volatility to be a strong predictor of future realized volatility. We find that option-implied volatility and skewness...... are also good predictors of future realized beta. Motivated by this finding, we establish a set of assumptions needed to construct a beta estimate from option-implied return moments using equity and index options. This beta can be computed using only option data on a single day. It is therefore potentially...

  13. Environmental marine geology of the Arctic Ocean

    International Nuclear Information System (INIS)

    Mudie, P.J.

    1991-01-01

    The Arctic Ocean and its ice cover are major regulators of Northern Hemisphere climate, ocean circulation and marine productivity. The Arctic is also very sensitive to changes in the global environment because sea ice magnifies small changes in temperature, and because polar regions are sinks for air pollutants. Marine geology studies are being carried out to determine the nature and rate of these environmental changes by study of modem ice and sea-bed environments, and by interpretation of geological records imprinted in the sea-floor sediments. Sea ice camps, an ice island, and polar icebreakers have been used to study both western and eastern Arctic Ocean basins. Possible early warning signals of environmental changes in the Canadian Arctic are die-back in Arctic sponge reefs, outbreaks of toxic dinoflagellates, and pesticides in the marine food chain. Eastern Arctic ice and surface waters are contaminated by freon and radioactive fallout from Chernobyl. At present, different sedimentary processes operate in the pack ice-covered Canadian polar margin than in summer open waters off Alaska and Eurasia. The geological records, however, suggest that a temperature increase of 1-4 degree C would result in summer open water throughout the Arctic, with major changes in ocean circulation and productivity of waters off Eastern North America, and more widespread transport of pollutants from eastern to western Arctic basins. More studies of longer sediment cores are needed to confirm these interpretations, but is is now clear that the Arctic Ocean has been the pacemaker of climate change during the past 1 million years

  14. Initial opening of the Eurasian Basin, Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Kai Berglar

    2016-10-01

    Full Text Available Analysis of the transition from the NE Yermak Plateau into the oceanic Eurasian Basin sheds light on the Paleocene formation of this Arctic basin. Newly acquired multichannel seismic data with a 3600 m long streamer shot during ice-free conditions enables the interpretation of crustal structures. Evidence is provided that no major compressional deformation affected the NE Yermak Plateau. The seismic data reveal that the margin is around 80 km wide and consists of rotated fault blocks, major listric normal faults, and half-grabens filled with syn-rift sediments. Taking into account published magnetic and gravimetric data, this setting is interpreted as a rifted continental margin, implying that the NE Yermak Plateau is of continental origin. The transition from the Yermak Plateau to the oceanic Eurasian Basin might be located at a prominent basement high, probably formed by exhumed mantle. In contrast to the Yermak Plateau margin, the North Barents Sea continental margin shows a steep continental slope with a relatively abrupt transition to the oceanic domain. Based on one composite seismic line, it is speculated that the initial opening direction of the Eurasian Basin in the Arctic Ocean was highly oblique to the present day seafloor spreading direction.

  15. Implied terms in English and Romanian law

    Directory of Open Access Journals (Sweden)

    Stefan Dinu

    2015-12-01

    Full Text Available This study analyses the matter of implied terms from the point of view of both English and Romanian law. First, the introductory section provides a brief overview of implied terms, by defining this class of contractual clauses and by providing their general features. Second, the English law position is analysed, where it is generally recognised that a term may be implied in one of three manners, which are described in turn. An emp hasis is made on the Privy Council’s decision in Attorney General of Belize v Belize Telecom Ltd and its impact. Third, the Romanian law position is described, the starting point of the discussion being represented by the provisions of Article 1272 of the 2009 Civil Code. Fourth, the study ends by mentioning some points of comparison between the two legal systems in what concerns the approach towards implied terms.

  16. High sedimentation rates in the Early Triassic after latest Permian mass extinction: Carbonate production is main factor in non-Arctic regions

    Science.gov (United States)

    Horacek, Micha; Brandner, Rainer

    2016-04-01

    A substantial change in sedimentation rates towards higher values has been documented from the Late Permian to the Lower Triassic. Although it is assumed and also has been shown that the deposition of siliciclastic material increased in the Lower Triassic due to stronger erosion because of loss of land cover and increased chemical and physical weathering with extreme climate warming, the main sediment production occurred by marine carbonate production. Still, carbonate production might have been significantly influenced by weathering and erosion in the hinterland, as the transport of dust by storms into the ocean water probably was a main nutrient source for microbial carbonate producers, because "normal" nutrient supply by ocean circulation, i. e. upwelling was strongly reduced due to the elevated temperatures resulting in water-column stratification . Sediment accumulation was also clearly influenced by the paleo-geographic and latitudinal position, with lower carbonate production and sedimentation rates in moderate latitudes. The existence of a "boundary clay" and microbial carbonate mounds and layers in the immediate aftermath of the latest Permian mass extinction points towards a development from a short-timed acid ocean water - resulting in a carbonate production gap and the deposition of the boundary clay towards the deposition of the microbial mounds and layers due to the microbial production of micro-environments with higher alkalinity allowing the production of carbonate. After the return of the ocean water to normal alkalinity planktic production of carbonate resulted in a very high sedimentation rate, especially taking into account the absence of carbonate producing eukaryotic algae and animals.

  17. Depositional History of the Western Amundsen Basin, Arctic Ocean, and Implications for Neogene Climate and Oceanographic Conditions

    Science.gov (United States)

    Hopper, J. R.; Castro, C. F.; Knutz, P. C.; Funck, T.

    2017-12-01

    Seismic reflection data collected in the western Amundsen Basin as part of the Law of the Sea program for the Kingdom of Denmark show a uniform and continuous cover of sediments over oceanic basement. An interpretation of seismic facies units shows that the depositional history of the basin reflects changing tectonic, climatic, and oceanographic conditions throughout the Cenozoic. In this contribution, the Miocene to present history is summarized. Two distinct changes in the depositional environment are proposed, first in response to the development of a deep water connection between the Arctic and North Atlantic, and the second in response to the onset of perennial sea ice cover in the Arctic. In the early to mid-Miocene, a buildup of contourite deposits indicates a distinct change in sedimentation that is particularly well developed near the flank of the Lomonosov Ridge. It is suggested that this is a response to the opening of the Fram Strait and the establishment of geostrophic bottom currents that flowed from the Laptev Sea towards Greenland. These deposits are overlain by a seismic facies unit characterized by buried channels and erosional features. These include prominent basinward levee systems that suggest a channel morphology maintained by overbank deposition of muddy sediments carried by suspension currents periodically spilling over the channel pathway. These deposits indicate a change to a much higher energy environment that is proposed to be a response to brine formation associated with the onset of perennial sea ice cover in the Arctic Ocean. This interpretation implies that the development of extensive sea ice cover results in a significant change in the energy environment of the ocean that is reflected in the depositional and erosional patterns observed. The lack of similar high energy erosional features and the presence of contourite deposits throughout most of the Miocene may indicate the Arctic Ocean was relatively ice-free until the very latest

  18. Development of pan-Arctic database for river chemistry

    Science.gov (United States)

    McClelland, J.W.; Holmes, R.M.; Peterson, B.J.; Amon, R.; Brabets, T.; Cooper, L.; Gibson, J.; Gordeev, V.V.; Guay, C.; Milburn, D.; Staples, R.; Raymond, P.A.; Shiklomanov, I.; Striegl, Robert G.; Zhulidov, A.; Gurtovaya, T.; Zimov, S.

    2008-01-01

    More than 10% of all continental runoff flows into the Arctic Ocean. This runoff is a dominant feature of the Arctic Ocean with respect to water column structure and circulation. Yet understanding of the chemical characteristics of runoff from the pan-Arctic watershed is surprisingly limited. The Pan- Arctic River Transport of Nutrients, Organic Matter, and Suspended Sediments ( PARTNERS) project was initiated in 2002 to help remedy this deficit, and an extraordinary data set has emerged over the past few years as a result of the effort. This data set is publicly available through the Cooperative Arctic Data and Information Service (CADIS) of the Arctic Observing Network (AON). Details about data access are provided below.

  19. Evidence of in situ microbial activity and sulphidogenesis in perennially sub-0 °C and hypersaline sediments of a high Arctic permafrost spring.

    Science.gov (United States)

    Lamarche-Gagnon, Guillaume; Comery, Raven; Greer, Charles W; Whyte, Lyle G

    2015-01-01

    The lost hammer (LH) spring perennially discharges subzero hypersaline reducing brines through thick layers of permafrost and is the only known terrestrial methane seep in frozen settings on Earth. The present study aimed to identify active microbial communities that populate the sediments of the spring outlet, and verify whether such communities vary seasonally and spatially. Microcosm experiments revealed that the biological reduction of sulfur compounds (SR) with hydrogen (e.g., sulfate reduction) was potentially carried out under combined hypersaline and subzero conditions, down to -20 °C, the coldest temperature ever recorded for SR. Pyrosequencing analyses of both 16S rRNA (i.e., cDNA) and 16S rRNA genes (i.e., DNA) of sediments retrieved in late winter and summer indicated fairly stable bacterial and archaeal communities at the phylum level. Potentially active bacterial and archaeal communities were dominated by clades related to the T78 Chloroflexi group and Halobacteria species, respectively. The present study indicated that SR, hydrogenotrophy (possibly coupled to autotrophy), and short-chain alkane degradation (other than methane), most likely represent important, previously unaccounted for, metabolic processes carried out by LH microbial communities. Overall, the obtained findings provided additional evidence that the LH system hosts active communities of anaerobic, halophilic, and cryophilic microorganisms despite the extreme conditions in situ.

  20. Detecting and Understanding Changing Arctic Carbon Emissions

    Science.gov (United States)

    Bruhwiler, L.

    2017-12-01

    Warming in the Arctic has proceeded faster than anyplace on Earth. Our current understanding of biogeochemistry suggests that we can expect feedbacks between climate and carbon in the Arctic. Changes in terrestrial fluxes of carbon can be expected as the Arctic warms, and the vast stores of organic carbon frozen in Arctic soils could be mobilized to the atmosphere, with possible significant impacts on global climate. Quantifying trends in Arctic carbon exchanges is important for policymaking because greater reductions in anthropogenic emissions may be required to meet climate goals. Observations of greenhouse gases in the Arctic and globally have been collected for several decades. Analysis of this data does not currently support significantly changed Arctic emissions of CH4, however it is difficult to detect changes in Arctic emissions because of transport from lower latitudes and large inter-annual variability. Unfortunately, current space-based remote sensing systems have limitations at Arctic latitudes. Modeling systems can help untangle the Arctic budget of greenhouse gases, but they are dependent on underlying prior fluxes, wetland distributions and global anthropogenic emissions. Also, atmospheric transport models may have significant biases and errors. For example, unrealistic near-surface stability can lead to underestimation of emissions in atmospheric inversions. We discuss our current understanding of the Arctic carbon budget from both top-down and bottom-up approaches. We show that current atmospheric inversions agree well on the CH4 budget. On the other hand, bottom-up models vary widely in their predictions of natural emissions, with some models predicting emissions too large to be accommodated by the budget implied by global observations. Large emissions from the shallow Arctic ocean are also inconsistent with atmospheric observations. We also discuss the sensitivity of the current atmospheric network to what is likely small, gradual increases in

  1. Arctic Shipping

    DEFF Research Database (Denmark)

    Hansen, Carsten Ørts; Grønsedt, Peter; Lindstrøm Graversen, Christian

    This report forms part of the ambitious CBS Maritime research initiative entitled “Competitive Challenges and Strategic Development Potential in Global Maritime Industries” which was launched with the generous support of the Danish Maritime Fund. The competitiveness initiative targets specific ma......, the latter aiming at developing key concepts and building up a basic industry knowledge base for further development of CBS Maritime research and teaching. This report attempts to map the opportunities and challenges for the maritime industry in an increasingly accessible Arctic Ocean...

  2. Geochemistry of clathrate-derived methane in Arctic Ocean waters

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, S.M.; Reagan, M.T.; Moridis, G.J.; Cameron-Smith, P.J.

    2010-03-15

    Alterations to the composition of seawater are estimated for microbial oxidation of methane from large polar clathrate destabilizations, which may arise in the coming century. Gas fluxes are taken from porous flow models of warming Arctic sediment. Plume spread parameters are then used to bracket the volume of dilution. Consumption stoichiometries for the marine methanotrophs are based on growth efficiency and elemental/enzyme composition data. The nutritional demand implied by extra CH{sub 4} removal is compared with supply in various high latitude water masses. For emissions sized to fit the shelf break, reaction potential begins at one hundred micromolar and falls to order ten a thousand kilometers downstream. Oxygen loss and carbon dioxide production are sufficient respectively to hypoxify and acidify poorly ventilated basins. Nitrogen and the monooxygenase transition metals may be depleted in some locations as well. Deprivation is implied relative to existing ecosystems, along with dispersal of the excess dissolved gas. Physical uncertainties are inherent in the clathrate abundance, patch size, outflow buoyancy and mixing rate. Microbial ecology is even less defined but may involve nutrient recycling and anaerobic oxidizers.

  3. Implied Volatility Surface: Construction Methodologies and Characteristics

    OpenAIRE

    Cristian Homescu

    2011-01-01

    The implied volatility surface (IVS) is a fundamental building block in computational finance. We provide a survey of methodologies for constructing such surfaces. We also discuss various topics which can influence the successful construction of IVS in practice: arbitrage-free conditions in both strike and time, how to perform extrapolation outside the core region, choice of calibrating functional and selection of numerical optimization algorithms, volatility surface dynamics and asymptotics.

  4. Arctic Ocean Scientific Drilling: The Next Frontier

    Directory of Open Access Journals (Sweden)

    Ruediger Stein

    2010-04-01

    Full Text Available The modern Arctic Ocean appears to be changing faster than any other region on Earth. To understand the potential extent of high latitude climate change, it is necessary to sample the history stored in the sediments filling the basins and covering the ridges of the Arctic Ocean. These sediments have been imaged with seismic reflection data, but except for the superficial record, which has been piston cored, they have been sampled only on the Lomonosov Ridge in 2004 during the Arctic Coring Expedition (ACEX-IODP Leg 302; Backman et al., 2006 and in 1993 in the ice-free waters in the Fram Strait/Yermak Plateau area (ODP Leg 151; Thiede et al., 1996.Although major progress in Arctic Ocean research has been made during the last few decades, the short- and long-term paleoceanographic and paleoclimatic history as well as its plate-tectonic evolution are poorly known compared to the other oceans. Despite the importance of the Arctic in the climate system, the database we have from this area is still very weak. Large segments of geologic time have not been sampled in sedimentary sections. The question of regional variations cannot be addressed.

  5. Cesium-137 contamination in Arctic Ocean ice

    International Nuclear Information System (INIS)

    Meese, D.; Tucker, W.; Cooper, L.; Larsen, I.L.; Grebmeier, J.

    1995-01-01

    Sea ice and ice-borne sediment samples were collected across the western Arctic basin on the joint US/Canada Arctic Ocean Section during August 1994. Samples were processed on board and returned at the completion of the cruise to Oak Ridge National Laboratory for analysis. Sediment was observed on the surface and in the ice from the southern ice limit in the Chukchi Sea to the North Pole. Preliminary results on the ice-borne sediment samples show widespread elevated concentrations of 137 Cs, ranging from 4.9 to 73 mBq g dry weight -1 . An analysis of the measurements indicate that sea ice is primary transport mechanism by which contaminated sediments are redistributed throughout the Arctic Ocean and possibly exported into the Greenland Sea and North Atlantic through Fram Strait. The wide variability in the ice-borne sediment concentrations of 137 Cs measured along the transect argues that contaminants incorporated on the Siberian shelves can follow much more variable trajectories than is suggested by mean ice drift calculations. 2 figs

  6. Active molecular iodine photochemistry in the Arctic.

    Science.gov (United States)

    Raso, Angela R W; Custard, Kyle D; May, Nathaniel W; Tanner, David; Newburn, Matt K; Walker, Lawrence; Moore, Ronald J; Huey, L G; Alexander, Liz; Shepson, Paul B; Pratt, Kerri A

    2017-09-19

    During springtime, the Arctic atmospheric boundary layer undergoes frequent rapid depletions in ozone and gaseous elemental mercury due to reactions with halogen atoms, influencing atmospheric composition and pollutant fate. Although bromine chemistry has been shown to initiate ozone depletion events, and it has long been hypothesized that iodine chemistry may contribute, no previous measurements of molecular iodine (I 2 ) have been reported in the Arctic. Iodine chemistry also contributes to atmospheric new particle formation and therefore cloud properties and radiative forcing. Here we present Arctic atmospheric I 2 and snowpack iodide (I - ) measurements, which were conducted near Utqiaġvik, AK, in February 2014. Using chemical ionization mass spectrometry, I 2 was observed in the atmosphere at mole ratios of 0.3-1.0 ppt, and in the snowpack interstitial air at mole ratios up to 22 ppt under natural sunlit conditions and up to 35 ppt when the snowpack surface was artificially irradiated, suggesting a photochemical production mechanism. Further, snow meltwater I - measurements showed enrichments of up to ∼1,900 times above the seawater ratio of I - /Na + , consistent with iodine activation and recycling. Modeling shows that observed I 2 levels are able to significantly increase ozone depletion rates, while also producing iodine monoxide (IO) at levels recently observed in the Arctic. These results emphasize the significance of iodine chemistry and the role of snowpack photochemistry in Arctic atmospheric composition, and imply that I 2 is likely a dominant source of iodine atoms in the Arctic.

  7. Politics of Sustainability in the Arctic

    DEFF Research Database (Denmark)

    Gad, Ulrik Pram; Jakobsen, Uffe; Strandsbjerg, Jeppe

    2017-01-01

    The concept of sustainability has become central in arctic politics. However, there is little agreement on what ‘sustainable’ means. For different actors (governments, indigenous people, NGOs, etc.) the concept implies different sets of opportunities and precautions. Sustainability, therefore...... the role of sustainability in political and economic strategies in the Arctic. Sustainability has become a fundamental concept that orders the relationship between the environment (nature) and development (economy), however, in the process rearticulating other concepts such as identity (society). Hence, we...... to outline an agenda for how to study the way in which sustainability works as a political concept....

  8. Asset allocation using option-implied moments

    Science.gov (United States)

    Bahaludin, H.; Abdullah, M. H.; Tolos, S. M.

    2017-09-01

    This study uses an option-implied distribution as the input in asset allocation. The computation of risk-neutral densities (RND) are based on the Dow Jones Industrial Average (DJIA) index option and its constituents. Since the RNDs estimation does not incorporate risk premium, the conversion of RND into risk-world density (RWD) is required. The RWD is obtained through parametric calibration using the beta distributions. The mean, volatility, and covariance are then calculated to construct the portfolio. The performance of the portfolio is evaluated by using portfolio volatility and Sharpe ratio.

  9. XBRL How It Implies The Audit Process

    Directory of Open Access Journals (Sweden)

    Sepky Mardian

    2015-08-01

    Full Text Available This article aimed to know what is XBRL how it works and it implies to audit process. XBRL as a new tool was expected to produce a timelines reliable and credible financial reporting. With its real-time and interactive data XBRL will help the investor and other stakeholder in receiving storing analyzing the information quickly. While in audit profession XBRL will speed up the audit process save the audit cost and increase the revenue. However in fact XBRL will make it happen if it was implemented and integrated to an information system owned by datainformation provider.

  10. A quantitative x-ray diffraction inventory of volcaniclastic inputs into the marine sediment archives off Iceland: a contribution to the Volcanoes in the Arctic System programme

    Directory of Open Access Journals (Sweden)

    Dennis D. Eberl

    2013-02-01

    Full Text Available This paper re-evaluates how well quantitative x-ray diffraction (qXRD can be used as an exploratory method of the weight percentage (wt% of volcaniclastic sediment, and to identify tephra events in marine cores. In the widely used RockJock v6 software programme, qXRD tephra and glass standards include the rhyodacite White River tephra (Alaska, a rhyolitic tephra (Hekla-4 and the basaltic Saksunarvatn tephra. Experiments of adding known wt% of tephra to felsic bedrock samples indicated that additions ≥10 wt% are accurately detected, but reliable estimates of lesser amounts are masked by amorphous material produced by milling. Volcaniclastic inputs range between 20 and 50 wt%. Primary tephra events are identified as peaks in residual qXRD glass wt% from fourth-order polynomial fits. In cores where tephras have been identified by shard counts in the >150 µm fraction, there is a positive correlation (validation with peaks in the wt% glass estimated by qXRD. Geochemistry of tephra shards confirms the presence of several Hekla-sourced tephras in cores B997-317PC1 and -319PC2 on the northern Iceland shelf. In core B997-338 (north-west Iceland, there are two rhyolitic tephras separated by ca. 100 cm with uncorrected radiocarbon dates on articulated shells of around 13 000 yr B.P. These tephras may be correlatives of the Borrobol and Penifiler tephras found in Scotland. The number of Holocene tephra events per 1000 yr was estimated from qXRD on 16 cores and showed a bimodal distribution with an increased number of events in both the late and early Holocene.

  11. Anthropogenic radionuclides in the Arctic Ocean. Distribution and pathways

    International Nuclear Information System (INIS)

    Josefsson, Dan

    1998-05-01

    Anthropogenic radionuclide concentrations have been determined in seawater and sediment samples collected in 1991, 1994 and 1996 in the Eurasian Arctic shelf and interior. Global fallout, releases from European reprocessing plants and the Chernobyl accident are identified as the three main sources. From measurements in the Eurasian shelf seas it is concluded that the total input of 134 Cs, 137 Cs and 90 Sr from these sources has been decreasing during the 1990's, while 129 I has increased. The main fraction of the reprocessing and Chernobyl activity found in Arctic Ocean surface layer is transported from the Barents Sea east along the Eurasian Arctic shelf seas to the Laptev Sea before entering the Nansen Basin. This inflow results in highest 137 Cs, 129 I and 90 Sr concentrations in the Arctic Ocean surface layers, and continuously decreasing concentrations with depth. Chernobyl-derived 137 Cs appeared in the central parts of the Arctic Ocean around 1991, and in the mid 1990's the fraction to total 137 Cs was approximately 30% in the entire Eurasian Arctic region. The transfer times for releases from Sellafield are estimated to be 5-7 years to the SE Barents Sea, 7-9 years to the Kara Sea, 10-11 years to the Laptev Sea and 12-14 years to the central Arctic Ocean. Global fallout is the primary source of plutonium with highest concentrations found in the Atlantic layer of the Arctic Ocean. When transported over the shallow shelf seas, particle reactive transuranic elements experience an intense scavenging. A rough estimate shows that approximately 75% of the plutonium entering the Kara and Laptev Seas are removed to the sediment. High seasonal riverine input of 239 , 240 Pu is observed near the mouths of the large Russian rivers. Sediment inventories show much higher concentrations on the shelf compared to the deep Arctic Ocean. This is primarily due to the low particle flux in the open ocean

  12. Arctic Ocean Paleoceanography and Future IODP Drilling

    Science.gov (United States)

    Stein, Ruediger

    2015-04-01

    Although the Arctic Ocean is a major player in the global climate/earth system, this region is one of the last major physiographic provinces on Earth where the short- and long-term geological history is still poorly known. This lack in knowledge is mainly due to the major technological/logistical problems in operating within the permanently ice-covered Arctic region which makes it difficult to retrieve long and undisturbed sediment cores. Prior to 2004, in the central Arctic Ocean piston and gravity coring was mainly restricted to obtaining near-surface sediments, i.e., only the upper 15 m could be sampled. Thus, all studies were restricted to the late Pliocene/Quaternary time interval, with a few exceptions. These include the four short cores obtained by gravity coring from drifting ice floes over the Alpha Ridge, where older pre-Neogene organic-carbon-rich muds and laminated biosiliceous oozes were sampled. Continuous central Arctic Ocean sedimentary records, allowing a development of chronologic sequences of climate and environmental change through Cenozoic times and a comparison with global climate records, however, were missing prior to the IODP Expedition 302 (Arctic Ocean Coring Expedition - ACEX), the first scientific drilling in the central Arctic Ocean. By studying the unique ACEX sequence, a large number of scientific discoveries that describe previously unknown Arctic paleoenvironments, were obtained during the last decade (for most recent review and references see Stein et al., 2014). While these results from ACEX were unprecedented, key questions related to the climate history of the Arctic Ocean remain unanswered, in part because of poor core recovery, and in part because of the possible presence of a major mid-Cenozoic hiatus or interval of starved sedimentation within the ACEX record. In order to fill this gap in knowledge, international, multidisciplinary expeditions and projects for scientific drilling/coring in the Arctic Ocean are needed. Key

  13. Measurement contextuality is implied by macroscopic realism

    International Nuclear Information System (INIS)

    Chen Zeqian; Montina, A.

    2011-01-01

    Ontological theories of quantum mechanics provide a realistic description of single systems by means of well-defined quantities conditioning the measurement outcomes. In order to be complete, they should also fulfill the minimal condition of macroscopic realism. Under the assumption of outcome determinism and for Hilbert space dimension greater than 2, they were all proved to be contextual for projective measurements. In recent years a generalized concept of noncontextuality was introduced that applies also to the case of outcome indeterminism and unsharp measurements. It was pointed out that the Beltrametti-Bugajski model is an example of measurement noncontextual indeterminist theory. Here we provide a simple proof that this model is the only one with such a feature for projective measurements and Hilbert space dimension greater than 2. In other words, there is no extension of quantum theory providing more accurate predictions of outcomes and simultaneously preserving the minimal labeling of events through projective operators. As a corollary, noncontextuality for projective measurements implies noncontextuality for unsharp measurements. By noting that the condition of macroscopic realism requires an extension of quantum theory, unless a breaking of unitarity is invoked, we arrive at the conclusion that the only way to solve the measurement problem in the framework of an ontological theory is by relaxing the hypothesis of measurement noncontextuality in its generalized sense.

  14. Cool episodes in Early Tertiary Arctic climate: Evidence from Svalbard

    Science.gov (United States)

    Spielhagen, R. F.; Tripati, A.

    2009-04-01

    The Arctic is a climatically sensitive and important region. However, very little is known about the climatic and oceanographic evolution of the area, particularly prior to the Neogene. Until recently, the Arctic was assumed to be characterized by relatively warm conditions during the early Cenozoic. The Early Tertiary sedimentary sequence on Svalbard contains several layers with coal seams and broad-leaved plants which were commonly accepted as indicators of a generally temperate-warm climate. Here we report on the intermittent occurrence of certain temperature indicators in the succession, which may represent the first northern high-latitude record of near-freezing temperatures for the early Cenozoic. Besides the findings of probably ice-rafted erratic clasts in the Paleocene and Eocene sandstones and shales, we note especially the occurrence of glendonites which are pseudomorphs of calcite after ikaite (calcium carbonate hexahydrate). We measured the chemical composition of Svalbard glendonites which is almost identical to that of similar pseudomorphs from the Lower Cretaceaous of Northern Canada. Mass spectrometric analyses of the glendonite calcite gave very low carbon isotope values. These values suggest a provenance of the calcium carbonate from marine organic carbon and connect our glendonites to the precursor mineral ikaite which has similar low values. Since a variety of studies has demonstrated that ikaite is stable only at temperatures close to freezing point, we have to infer low temperatures also for the deepositional environment of which the sediments were deposited that now hold glendonites. These results imply the occurrence of cooling phases episodically during the warm background climate of the Paleocene and Eocene, suggesting that temperature variability was much greater than previously recognized.

  15. Approaching a Postcolonial Arctic

    DEFF Research Database (Denmark)

    Jensen, Lars

    2016-01-01

    This article explores different postcolonially configured approaches to the Arctic. It begins by considering the Arctic as a region, an entity, and how the customary political science informed approaches are delimited by their focus on understanding the Arctic as a region at the service...... of the contemporary neoliberal order. It moves on to explore how different parts of the Arctic are inscribed in a number of sub-Arctic nation-state binds, focusing mainly on Canada and Denmark. The article argues that the postcolonial can be understood as a prism or a methodology that asks pivotal questions to all...... approaches to the Arctic. Yet the postcolonial itself is characterised by limitations, not least in this context its lack of interest in the Arctic, and its bias towards conventional forms of representation in art. The article points to the need to develop a more integrated critique of colonial and neo...

  16. Clifford Algebra Implying Three Fermion Generations Revisited

    International Nuclear Information System (INIS)

    Krolikowski, W.

    2002-01-01

    The author's idea of algebraic compositeness of fundamental particles, allowing to understand the existence in Nature of three fermion generations, is revisited. It is based on two postulates. Primo, for all fundamental particles of matter the Dirac square-root procedure √p 2 → Γ (N) ·p works, leading to a sequence N=1, 2, 3, ... of Dirac-type equations, where four Dirac-type matrices Γ (N) μ are embedded into a Clifford algebra via a Jacobi definition introducing four ''centre-of-mass'' and (N - 1) x four ''relative'' Dirac-type matrices. These define one ''centre-of-mass'' and N - 1 ''relative'' Dirac bispinor indices. Secundo, the ''centre-of-mass'' Dirac bispinor index is coupled to the Standard Model gauge fields, while N - 1 ''relative'' Dirac bispinor indices are all free indistinguishable physical objects obeying Fermi statistics along with the Pauli principle which requires the full antisymmetry with respect to ''relative'' Dirac indices. This allows only for three Dirac-type equations with N = 1, 3, 5 in the case of N odd, and two with N = 2, 4 in the case of N even. The first of these results implies unavoidably the existence of three and only three generations of fundamental fermions, namely leptons and quarks, as labelled by the Standard Model signature. At the end, a comment is added on the possible shape of Dirac 3 x 3 mass matrices for four sorts of spin-1/2 fundamental fermions appearing in three generations. For charged leptons a prediction is m τ = 1776.80 MeV, when the input of experimental m e and m μ is used. (author)

  17. Clifford Algebra Implying Three Fermion Generations Revisited

    Science.gov (United States)

    Krolikowski, Wojciech

    2002-09-01

    The author's idea of algebraic compositeness of fundamental particles, allowing to understand the existence in Nature of three fermion generations, is revisited. It is based on two postulates. Primo, for all fundamental particles of matter the Dirac square-root procedure √ {p2} → {Γ }(N)p works, leading to a sequence N = 1,2,3, ... of Dirac-type equations, where four Dirac-type matrices {Γ }(N)μ are embedded into a Clifford algebra via a Jacobi definition introducing four ``centre-of-mass'' and (N-1)× four ``relative'' Dirac-type matrices. These define one ``centre-of-mass'' and (N-1) ``relative'' Dirac bispinor indices. Secundo, the ``centre-of-mass'' Dirac bispinor index is coupled to the Standard Model gauge fields, while (N-1) ``relative'' Dirac bispinor indices are all free indistinguishable physical objects obeying Fermi statistics along with the Pauli principle which requires the full antisymmetry with respect to ``relative'' Dirac indices. This allows only for three Dirac-type equations with N = 1,3,5 in the case of N odd, and two with N = 2,4 in the case of N even. The first of these results implies unavoidably the existence of three and only three generations of fundamental fermions, namely leptons and quarks, as labelled by the Standard Model signature. At the end, a comment is added on the possible shape of Dirac 3x3 mass matrices for four sorts of spin-1/2 fundamental fermions appearing in three generations. For charged leptons a prediction is mτ = 1776.80 MeV, when the input of experimental me and mμ is used.

  18. Radioactivity contamination of the Russian Arctic Seas

    Energy Technology Data Exchange (ETDEWEB)

    Rissanen, K. [STUK Radiation and Nuclear Safety Authority, Rovaniemi (Finland); Ikaeheimonen, T.K. [STUK Radiation and Nuclear Safety Authority, Helsinki (Finland); Matishov, D.; Matishov, G.G. [Murmansk Marine Biological Inst., Murmansk (Russian Federation)

    2001-04-01

    The levels of the anthropogenic radionuclides in the Russian Arctic Seas are low compared to the potential sources of pollution and originata mainly from the global fallout, Chernobyl fallout and from the western nuclear fuel reprocessing plants. Fresh release of radioactivity was noticed in this study only in the Kola Bay and in two sampling locations in the White Sea. The increased {sup 137}Cs concentrations measured in the estuaries of River Dvina and River Yenisey are caused by the riverine transport from the large catchment area. The sediments of the Russian Arctic Seas are hard. Good and enough long cores for sedimentation rate determination were obtained only in two locations in the White Sea. All the cores from river estuaries were badly mixed. (EHS)

  19. Flocculated meltwater particles control Arctic land-sea fluxes of labile iron

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Elberling, Bo; Winter, Christian

    2016-01-01

    Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our...... the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters....

  20. Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments

    Science.gov (United States)

    Dixon, John

    2015-04-01

    Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of non-glacierized Arctic vs. subarctic drainage basins reveals the effects of these controls. All drainage basins exhibit considerable variability in rates of sediment and solute fluxes. For the non-glacierized drainage basins there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. Basins underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted basins generating greater fluxes. For glacierized basins the fundamental difference to non-glacierized basins is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage basins with upland basins generating greater sediment and solute transfers than lowland basins. For glacierized basins the effects of biology and regolith appear to be

  1. The Arctic Turn

    DEFF Research Database (Denmark)

    Rahbek-Clemmensen, Jon

    2018-01-01

    In October 2006, representatives of the Arctic governments met in Salekhard in northern Siberia for the biennial Arctic Council ministerial meeting to discuss how the council could combat regional climate change, among other issues. While most capitals were represented by their foreign minister......, a few states – Canada, Denmark, and the United States – sent other representatives. There was nothing unusual about the absence of Per Stig Møller, the Danish foreign minister – a Danish foreign minister had only once attended an Arctic Council ministerial meeting (Arctic Council 2016). Møller......’s nonappearance did, however, betray the low status that Arctic affairs had in the halls of government in Copenhagen. Since the end of the Cold War, where Greenland had helped tie Denmark and the US closer together due to its geostrategically important position between North America and the Soviet Union, Arctic...

  2. Collaboration across the Arctic

    DEFF Research Database (Denmark)

    Huppert, Verena Gisela; Chuffart, Romain François R.

    2017-01-01

    The Arctic is witnessing the rise of a new paradigm caused by an increase in pan-Arctic collaborations which co-exist with the region’s traditional linkages with the South. Using an analysis of concrete examples of regional collaborations in the Arctic today in the fields of education, health...... and infrastructure, this paper questions whether pan-Arctic collaborations in the Arctic are more viable than North-South collaborations, and explores the reasons behind and the foreseeable consequences of such collaborations. It shows that the newly emerging East-West paradigm operates at the same time...... as the traditional North-South paradigm, with no signs of the East-West paradigm being more viable in the foreseeable future. However, pan-Arctic collaboration, both due to pragmatic reasons and an increased awareness of similarities, is likely to increase in the future. The increased regionalization process...

  3. Arctic wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Peltola, E. [Kemijoki Oy (Finland); Holttinen, H.; Marjaniemi, M. [VTT Energy, Espoo (Finland); Tammelin, B. [Finnish Meteorological Institute, Helsinki (Finland)

    1998-12-31

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  4. Arctic wind energy

    International Nuclear Information System (INIS)

    Peltola, E.; Holttinen, H.; Marjaniemi, M.; Tammelin, B.

    1998-01-01

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  5. Late Cretaceous seasonal ocean variability from the Arctic.

    Science.gov (United States)

    Davies, Andrew; Kemp, Alan E S; Pike, Jennifer

    2009-07-09

    The modern Arctic Ocean is regarded as a barometer of global change and amplifier of global warming and therefore records of past Arctic change are critical for palaeoclimate reconstruction. Little is known of the state of the Arctic Ocean in the greenhouse period of the Late Cretaceous epoch (65-99 million years ago), yet records from such times may yield important clues to Arctic Ocean behaviour in near-future warmer climates. Here we present a seasonally resolved Cretaceous sedimentary record from the Alpha ridge of the Arctic Ocean. This palaeo-sediment trap provides new insight into the workings of the Cretaceous marine biological carbon pump. Seasonal primary production was dominated by diatom algae but was not related to upwelling as was previously hypothesized. Rather, production occurred within a stratified water column, involving specially adapted species in blooms resembling those of the modern North Pacific subtropical gyre, or those indicated for the Mediterranean sapropels. With increased CO(2) levels and warming currently driving increased stratification in the global ocean, this style of production that is adapted to stratification may become more widespread. Our evidence for seasonal diatom production and flux testify to an ice-free summer, but thin accumulations of terrigenous sediment within the diatom ooze are consistent with the presence of intermittent sea ice in the winter, supporting a wide body of evidence for low temperatures in the Late Cretaceous Arctic Ocean, rather than recent suggestions of a 15 degrees C mean annual temperature at this time.

  6. Active molecular iodine photochemistry in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Raso, Angela R.; Custard, Kyle D.; May, Nathaniel W.; Tanner, David; Newburn, Matthew K.; Walker, Lawrence R.; Moore, Ronald J.; Huey, L. G.; Alexander, Lizabeth; Shepson, Paul B.; Pratt, Kerri A.

    2017-09-05

    During springtime, the Arctic atmospheric boundary layer undergoes frequent rapid depletions in ozone and gaseous elemental mercury due to reactions with halogen atoms, influencing atmospheric composition and pollutant fate. Although bromine chemistry has been shown to initiate ozone depletion events, and it has long been hypothesized that iodine chemistry may contribute, no previous measurements of molecular iodine (I2) have been reported in the Arctic. Iodine chemistry also contributes to atmospheric new particle formation and therefore cloud properties and radiative forcing. Here we present Arctic atmospheric I2 and snowpack iodide (I-) measurements, which were conducted near Utqiagvik, AK, in February 2014. Using chemical ionization mass spectrometry, I2 was observed in the atmosphere at mole ratios of 0.3–1.0 ppt, and in the snowpack interstitial air at mole ratios up to 22 ppt under natural sunlit conditions and up to 35 ppt when the snowpack surface was artificially irradiated, suggesting a photochemical production mechanism. Further, snow meltwater I-measurements showed enrichments of up to ~1,900 times above the seawater ratio of I-/Na+, consistent with iodine activation and recycling. Modeling shows that observed I2 levels are able to significantly increase ozone depletion rates, while also producing iodine monoxide (IO) at levels recently observed in the Arctic. These results emphasize the significance of iodine chemistry and the role of snowpack photochemistry in Arctic atmospheric composition, and imply that I2 is likely a dominant source of iodine atoms in the Arctic.

  7. Arctic-COLORS (Coastal Land Ocean Interactions in the Arctic) - a NASA field campaign scoping study to examine land-ocean interactions in the Arctic

    Science.gov (United States)

    Hernes, P.; Tzortziou, M.; Salisbury, J.; Mannino, A.; Matrai, P.; Friedrichs, M. A.; Del Castillo, C. E.

    2014-12-01

    The Arctic region is warming faster than anywhere else on the planet, triggering rapid social and economic changes and impacting both terrestrial and marine ecosystems. Yet our understanding of critical processes and interactions along the Arctic land-ocean interface is limited. Arctic-COLORS is a Field Campaign Scoping Study funded by NASA's Ocean Biology and Biogeochemistry Program that aims to improve understanding and prediction of land-ocean interactions in a rapidly changing Arctic coastal zone, and assess vulnerability, response, feedbacks and resilience of coastal ecosystems, communities and natural resources to current and future pressures. Specific science objectives include: - Quantify lateral fluxes to the arctic inner shelf from (i) rivers and (ii) the outer shelf/basin that affect biology, biodiversity, biogeochemistry (i.e. organic matter, nutrients, suspended sediment), and the processing rates of these constituents in coastal waters. - Evaluate the impact of the thawing of Arctic permafrost within the river basins on coastal biology, biodiversity and biogeochemistry, including various rates of community production and the role these may play in the health of regional economies. - Assess the impact of changing Arctic landfast ice and coastal sea ice dynamics. - Establish a baseline for comparison to future change, and use state-of-the-art models to assess impacts of environmental change on coastal biology, biodiversity and biogeochemistry. A key component of Arctic-COLORS will be the integration of satellite and field observations with coupled physical-biogeochemical models for predicting impacts of future pressures on Arctic, coastal ocean, biological processes and biogeochemical cycles. Through interagency and international collaborations, and through the organization of dedicated workshops, town hall meetings and presentations at international conferences, the scoping study engages the broader scientific community and invites participation of

  8. White Arctic vs. Blue Arctic: Making Choices

    Science.gov (United States)

    Pfirman, S. L.; Newton, R.; Schlosser, P.; Pomerance, R.; Tremblay, B.; Murray, M. S.; Gerrard, M.

    2015-12-01

    As the Arctic warms and shifts from icy white to watery blue and resource-rich, tension is arising between the desire to restore and sustain an ice-covered Arctic and stakeholder communities that hope to benefit from an open Arctic Ocean. If emissions of greenhouse gases to the atmosphere continue on their present trend, most of the summer sea ice cover is projected to be gone by mid-century, i.e., by the time that few if any interventions could be in place to restore it. There are many local as well as global reasons for ice restoration, including for example, preserving the Arctic's reflectivity, sustaining critical habitat, and maintaining cultural traditions. However, due to challenges in implementing interventions, it may take decades before summer sea ice would begin to return. This means that future generations would be faced with bringing sea ice back into regions where they have not experienced it before. While there is likely to be interest in taking action to restore ice for the local, regional, and global services it provides, there is also interest in the economic advancement that open access brings. Dealing with these emerging issues and new combinations of stakeholders needs new approaches - yet environmental change in the Arctic is proceeding quickly and will force the issues sooner rather than later. In this contribution we examine challenges, opportunities, and responsibilities related to exploring options for restoring Arctic sea ice and potential pathways for their implementation. Negotiating responses involves international strategic considerations including security and governance, meaning that along with local communities, state decision-makers, and commercial interests, national governments will have to play central roles. While these issues are currently playing out in the Arctic, similar tensions are also emerging in other regions.

  9. Entropy-based implied volatility and its information content

    NARCIS (Netherlands)

    X. Xiao (Xiao); C. Zhou (Chen)

    2016-01-01

    markdownabstractThis paper investigates the maximum entropy approach on estimating implied volatility. The entropy approach also allows to measure option implied skewness and kurtosis nonparametrically, and to construct confidence intervals. Simulations show that the en- tropy approach outperforms

  10. Money market rates and implied CCAPM rates: some international evidence

    OpenAIRE

    Yamin Ahmad

    2004-01-01

    New Neoclassical Synthesis models equate the instrument of monetary policy to the implied CCAPM rate arising from an Euler equation. This paper identifies monetary policy shocks within six of the G7 countries and examines the movement of money market and implied CCAPM rates. The key result is that an increase in the nominal interest rate leads to a fall in the implied CCAPM rate. Incorporating habit still yields the same result. The findings suggest that the movement of these two rates implie...

  11. Implied Terms: The Foundation in Good Faith and Fair Dealing

    OpenAIRE

    2014-01-01

    With the aim of clarifying English law of implied terms in contracts and explaining their basis in the idea of good faith in performance, it is argued first that two, but no more, types of implied terms can be distinguished (terms implied in fact and terms implied by law), though it is explained why these types are frequently confused. Second, the technique of implication of terms is distinguished in most instances from the task of interpretation of contracts. Third, it is a...

  12. Arctic research vessel design would expand science prospects

    Science.gov (United States)

    Elsner, Robert; Kristensen, Dirk

    The U.S. polar marine science community has long declared the need for an arctic research vessel dedicated to advancing the study of northern ice-dominated seas. Planning for such a vessel began 2 decades ago, but competition for funding has prevented construction. A new design program is underway, and it shows promise of opening up exciting possibilities for new research initiatives in arctic marine science.With its latest design, the Arctic Research Vessel (ARV) has grown to a size and capability that will make it the first U.S. academic research vessel able to provide access to the Arctic Ocean. This ship would open a vast arena for new studies in the least known of the world's seas. These studies promise to rank high in national priority because of the importance of the Arctic Ocean as a source of data relating to global climate change. Other issues that demand attention in the Arctic include its contributions to the world's heat budget, the climate history buried in its sediments, pollution monitoring, and the influence of arctic conditions on marine renewable resources.

  13. The Forecast Performance of Competing Implied Volatility Measures

    DEFF Research Database (Denmark)

    Tsiaras, Leonidas

    This study examines the information content of alternative implied volatility measures for the 30 components of the Dow Jones Industrial Average Index from 1996 until 2007. Along with the popular Black-Scholes and "model-free" implied volatility expectations, the recently proposed corridor implie......, volatility definitions, loss functions and forecast evaluation settings....

  14. Arctic circulation regimes.

    Science.gov (United States)

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. © 2015 The Authors.

  15. Arctic carbon cycling

    NARCIS (Netherlands)

    Christensen, Torben R; Rysgaard, SØREN; Bendtsen, JØRGEN; Else, Brent; Glud, Ronnie N; van Huissteden, J.; Parmentier, F.J.W.; Sachs, Torsten; Vonk, J.E.

    2017-01-01

    The marine Arctic is considered a net carbon sink, with large regional differences in uptake rates. More regional modelling and observational studies are required to reduce the uncertainty among current estimates. Robust projections for how the Arctic Ocean carbon sink may evolve in the future are

  16. Arctic fox (Alopex lagopus) from the North Sea

    NARCIS (Netherlands)

    Langeveld, Bram W.; Mol, Dick; van der Plicht, Hans

    2018-01-01

    The first record of arctic fox Alopex lagopus (Linnaeus, 1758) from the Eurogeul area (North Sea) is reported based on a distal humerus fragment collected by private collectors from dredged sediments on ‘De Zandmotor’. It was radiocarbon dated to 29,900 + 550/- 490 BP (GrA-69520), which is younger

  17. Arctic Haze Analysis

    Science.gov (United States)

    Mei, Linlu; Xue, Yong

    2013-04-01

    The Arctic atmosphere is perturbed by nature/anthropogenic aerosol sources known as the Arctic haze, was firstly observed in 1956 by J. Murray Mitchell in Alaska (Mitchell, 1956). Pacyna and Shaw (1992) summarized that Arctic haze is a mixture of anthropogenic and natural pollutants from a variety of sources in different geographical areas at altitudes from 2 to 4 or 5 km while the source for layers of polluted air at altitudes below 2.5 km mainly comes from episodic transportation of anthropogenic sources situated closer to the Arctic. Arctic haze of low troposphere was found to be of a very strong seasonal variation characterized by a summer minimum and a winter maximum in Alaskan (Barrie, 1986; Shaw, 1995) and other Arctic region (Xie and Hopke, 1999). An anthropogenic factor dominated by together with metallic species like Pb, Zn, V, As, Sb, In, etc. and nature source such as sea salt factor consisting mainly of Cl, Na, and K (Xie and Hopke, 1999), dust containing Fe, Al and so on (Rahn et al.,1977). Black carbon and soot can also be included during summer time because of the mix of smoke from wildfires. The Arctic air mass is a unique meteorological feature of the troposphere characterized by sub-zero temperatures, little precipitation, stable stratification that prevents strong vertical mixing and low levels of solar radiations (Barrie, 1986), causing less pollutants was scavenged, the major revival pathway for particulates from the atmosphere in Arctic (Shaw, 1981, 1995; Heintzenberg and Larssen, 1983). Due to the special meteorological condition mentioned above, we can conclude that Eurasian is the main contributor of the Arctic pollutants and the strong transport into the Arctic from Eurasia during winter caused by the high pressure of the climatologically persistent Siberian high pressure region (Barrie, 1986). The paper intends to address the atmospheric characteristics of Arctic haze by comparing the clear day and haze day using different dataset

  18. Arctic Sea Level Reconstruction

    DEFF Research Database (Denmark)

    Svendsen, Peter Limkilde

    Reconstruction of historical Arctic sea level is very difficult due to the limited coverage and quality of tide gauge and altimetry data in the area. This thesis addresses many of these issues, and discusses strategies to help achieve a stable and plausible reconstruction of Arctic sea level from...... 1950 to today.The primary record of historical sea level, on the order of several decades to a few centuries, is tide gauges. Tide gauge records from around the world are collected in the Permanent Service for Mean Sea Level (PSMSL) database, and includes data along the Arctic coasts. A reasonable...... amount of data is available along the Norwegian and Russian coasts since 1950, and most published research on Arctic sea level extends cautiously from these areas. Very little tide gauge data is available elsewhere in the Arctic, and records of a length of several decades,as generally recommended for sea...

  19. Research with Arctic peoples

    DEFF Research Database (Denmark)

    Smith, H Sally; Bjerregaard, Peter; Chan, Hing Man

    2006-01-01

    Arctic peoples are spread over eight countries and comprise 3.74 million residents, of whom 9% are indigenous. The Arctic countries include Canada, Finland, Greenland (Denmark), Iceland, Norway, Russia, Sweden and the United States. Although Arctic peoples are very diverse, there are a variety...... of environmental and health issues that are unique to the Arctic regions, and research exploring these issues offers significant opportunities, as well as challenges. On July 28-29, 2004, the National Heart, Lung, and Blood Institute and the Canadian Institutes of Health Research co-sponsored a working group...... entitled "Research with Arctic Peoples: Unique Research Opportunities in Heart, Lung, Blood and Sleep Disorders". The meeting was international in scope with investigators from Greenland, Iceland and Russia, as well as Canada and the United States. Multiple health agencies from Canada and the United States...

  20. Evidence From Svalbard for Cool Episodes in Early Tertiary Arctic Climate

    Science.gov (United States)

    Spielhagen, R. F.; Tripati, A.; Mac Niocaill, C.

    2008-12-01

    The Arctic is a climatically sensitive and important region. However, very little is known about the climatic and oceanographic evolution of the area, particularly prior to the Neogene. Until recently, the Arctic was assumed to be characterized by relatively warm conditions during the early Cenozoic. The Early Tertiary sedimentary sequence on Svalbard contains several layers with coal seams and broad-leaved plants which were commonly accepted as indicators of a generally temperate-warm climate. Here we report on the intermittent occurrence of certain temperature indicators in the succession, which may represent the first northern high- latitude record of near-freezing temperatures for the early Cenozoic. Besides the findings of probably ice- rafted erratic clasts in the Paleocene and Eocene sandstones and shales, we note especially the occurrence of glendonites which are pseudomorphs of calcite after ikaite (calcium carbonate hexahydrate). Stratigraphic control for the most important glendonite layers was improved by paleomagnetic investigations on the host sediment. We measured the chemical composition of Svalbard glendonites which is almost identical to that of similar pseudomorphs from the Lower Cretaceaous of Northern Canada. Mass spectrometric analyses of the glendonite calcite gave very low carbon isotope values. These values suggest a provenance of the calcium carbonate from marine organic carbon and connect our glendonites to the precursor mineral ikaite which has similar low values. Since a variety of studies has demonstrated that ikaite is stable only at temperatures close to freezing point, we have to infer low temperatures also for the deepositional environment of which the sediments were deposited that now hold glendonites. These results imply the occurrence of cooling phases episodically during the warm background climate of the Paleocene and Eocene, suggesting that temperature variability was much greater than previously recognized.

  1. Across the Arctic Teachers Experience Field Research

    Science.gov (United States)

    Warnick, W. K.; Warburton, J.; Wiggins, H. V.; Marshall, S. A.; Darby, D. A.

    2005-12-01

    From studying snow geese on the North Slope of Alaska to sediment coring aboard the U.S. Coast Guard Cutter Healy in the Arctic Ocean, K-12 teachers embark on scientific expeditions as part of a program that strives to make science in the Arctic a "virtual" reality. In the past two years, seventeen K-12 teachers have participated in Teachers and Researchers Exploring and Collaborating (TREC), a program that pairs teachers with researchers to improve science education through arctic field experiences. TREC builds on the scientific and cultural opportunities of the Arctic, linking research and education through topics that naturally engage students and the wider public. TREC includes expeditions as diverse as studying plants at Toolik Field Station, a research facility located 150 miles above the Arctic Circle; climate change studies in Norway's Svalbard archipelago; studying rivers in Siberia; or a trans-arctic expedition aboard the USCGC Healy collecting an integrated geophysical data set. Funded by the National Science Foundation Office of Polar Programs, TREC offers educators experiences in scientific inquiry while encouraging the public and students to become active participants in the scientific inquiry by engaging them virtually in arctic research. TREC uses online outreach elements to convey the research experience to a broad audience. While in remote field locations, teachers and researchers interact with students and the public through online seminars and live calls from the field, online journals with accompanying photos, and online bulletin boards. Since the program's inception in 2004, numerous visitors have posted questions or interacted with teachers, researchers, and students through the TREC website (http://www.arcus.org/trec). TREC teachers are required to transfer their experience of research and current science into their classroom through the development of relevant activities and resources. Teachers and researchers are encouraged to participate

  2. Arctic Climate Systems Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ivey, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robinson, David G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boslough, Mark B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Backus, George A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Peterson, Kara J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); van Bloemen Waanders, Bart G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Swiler, Laura Painton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Desilets, Darin Maurice [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reinert, Rhonda Karen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This study began with a challenge from program area managers at Sandia National Laboratories to technical staff in the energy, climate, and infrastructure security areas: apply a systems-level perspective to existing science and technology program areas in order to determine technology gaps, identify new technical capabilities at Sandia that could be applied to these areas, and identify opportunities for innovation. The Arctic was selected as one of these areas for systems level analyses, and this report documents the results. In this study, an emphasis was placed on the arctic atmosphere since Sandia has been active in atmospheric research in the Arctic since 1997. This study begins with a discussion of the challenges and benefits of analyzing the Arctic as a system. It goes on to discuss current and future needs of the defense, scientific, energy, and intelligence communities for more comprehensive data products related to the Arctic; assess the current state of atmospheric measurement resources available for the Arctic; and explain how the capabilities at Sandia National Laboratories can be used to address the identified technological, data, and modeling needs of the defense, scientific, energy, and intelligence communities for Arctic support.

  3. Globalising the Arctic Climate:

    DEFF Research Database (Denmark)

    Corry, Olaf

    2017-01-01

    This chapter uses an object-oriented approach to explore how the Arctic is being constituted as an object of global governance within an emerging ‘global polity’, partly through geoengineering plans and political visions ('imaginaries'). It suggests that governance objects—the socially constructed...... on world politics. The emergence of the Arctic climate as a potential target of governance provides a case in point. The Arctic climate is becoming globalised, pushing it up the political agenda but drawing it away from its local and regional context....

  4. Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

    Science.gov (United States)

    Marzen, Rachel; DeNinno, Lauren H.; Cronin, Thomas M.

    2016-01-01

    Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

  5. Arctic Mixed Layer Dynamics

    National Research Council Canada - National Science Library

    Morison, James

    2003-01-01

    .... Over the years we have sought to understand the heat and mass balance of the mixed layer, marginal ice zone processes, the Arctic internal wave and mixing environment, summer and winter leads, and convection...

  6. Arctic Aerosols and Sources

    DEFF Research Database (Denmark)

    Nielsen, Ingeborg Elbæk

    2017-01-01

    Since the Industrial Revolution, the anthropogenic emission of greenhouse gases has been increasing, leading to a rise in the global temperature. Particularly in the Arctic, climate change is having serious impact where the average temperature has increased almost twice as much as the global during......, ammonium, black carbon, and trace metals. This PhD dissertation studies Arctic aerosols and their sources, with special focus on black carbon, attempting to increase the knowledge about aerosols’ effect on the climate in an Arctic content. The first part of the dissertation examines the diversity...... of aerosol emissions from an important anthropogenic aerosol source: residential wood combustion. The second part, characterizes the chemical and physical composition of aerosols while investigating sources of aerosols in the Arctic. The main instrument used in this research has been the state...

  7. Live from the Arctic

    Science.gov (United States)

    Warnick, W. K.; Haines-Stiles, G.; Warburton, J.; Sunwood, K.

    2003-12-01

    For reasons of geography and geophysics, the poles of our planet, the Arctic and Antarctica, are places where climate change appears first: they are global canaries in the mine shaft. But while Antarctica (its penguins and ozone hole, for example) has been relatively well-documented in recent books, TV programs and journalism, the far North has received somewhat less attention. This project builds on and advances what has been done to date to share the people, places, and stories of the North with all Americans through multiple media, over several years. In a collaborative project between the Arctic Research Consortium of the United States (ARCUS) and PASSPORT TO KNOWLEDGE, Live from the Arctic will bring the Arctic environment to the public through a series of primetime broadcasts, live and taped programming, interactive virtual field trips, and webcasts. The five-year project will culminate during the 2007-2008 International Polar Year (IPY). Live from the Arctic will: A. Promote global understanding about the value and world -wide significance of the Arctic, B. Bring cutting-edge research to both non-formal and formal education communities, C. Provide opportunities for collaboration between arctic scientists, arctic communities, and the general public. Content will focus on the following four themes. 1. Pan-Arctic Changes and Impacts on Land (i.e. snow cover; permafrost; glaciers; hydrology; species composition, distribution, and abundance; subsistence harvesting) 2. Pan-Arctic Changes and Impacts in the Sea (i.e. salinity, temperature, currents, nutrients, sea ice, marine ecosystems (including people, marine mammals and fisheries) 3. Pan-Arctic Changes and Impacts in the Atmosphere (i.e. precipitation and evaporation; effects on humans and their communities) 4. Global Perspectives (i.e. effects on humans and communities, impacts to rest of the world) In The Earth is Faster Now, a recent collection of comments by members of indigenous arctic peoples, arctic

  8. Implied liquidity : towards stochastic liquidity modeling and liquidity trading

    NARCIS (Netherlands)

    Corcuera, J.M.; Guillaume, F.M.Y.; Madan, D.B.; Schoutens, W.

    2010-01-01

    In this paper we introduce the concept of implied (il)liquidity of vanilla options. Implied liquidity is based on the fundamental theory of conic finance, in which the one-price model is abandoned and replaced by a two-price model giving bid and ask prices for traded assets. The pricing is done by

  9. Asymptotic formulae for implied volatility in the Heston model

    OpenAIRE

    Forde, Martin; Jacquier, Antoine; Mijatovic, Aleksandar

    2009-01-01

    In this paper we prove an approximate formula expressed in terms of elementary functions for the implied volatility in the Heston model. The formula consists of the constant and first order terms in the large maturity expansion of the implied volatility function. The proof is based on saddlepoint methods and classical properties of holomorphic functions.

  10. Anthropogenic radionuclides in the Arctic Ocean. Distribution and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Josefsson, Dan

    1998-05-01

    Anthropogenic radionuclide concentrations have been determined in seawater and sediment samples collected in 1991, 1994 and 1996 in the Eurasian Arctic shelf and interior. Global fallout, releases from European reprocessing plants and the Chernobyl accident are identified as the three main sources. From measurements in the Eurasian shelf seas it is concluded that the total input of {sup 134}Cs, {sup 137}Cs and {sup 90}Sr from these sources has been decreasing during the 1990`s, while {sup 129}I has increased. The main fraction of the reprocessing and Chernobyl activity found in Arctic Ocean surface layer is transported from the Barents Sea east along the Eurasian Arctic shelf seas to the Laptev Sea before entering the Nansen Basin. This inflow results in highest {sup 137}Cs, {sup 129}I and {sup 90}Sr concentrations in the Arctic Ocean surface layers, and continuously decreasing concentrations with depth. Chernobyl-derived {sup 137}Cs appeared in the central parts of the Arctic Ocean around 1991, and in the mid 1990`s the fraction to total {sup 137}Cs was approximately 30% in the entire Eurasian Arctic region. The transfer times for releases from Sellafield are estimated to be 5-7 years to the SE Barents Sea, 7-9 years to the Kara Sea, 10-11 years to the Laptev Sea and 12-14 years to the central Arctic Ocean. Global fallout is the primary source of plutonium with highest concentrations found in the Atlantic layer of the Arctic Ocean. When transported over the shallow shelf seas, particle reactive transuranic elements experience an intense scavenging. A rough estimate shows that approximately 75% of the plutonium entering the Kara and Laptev Seas are removed to the sediment. High seasonal riverine input of {sup 239}, {sup 240}Pu is observed near the mouths of the large Russian rivers. Sediment inventories show much higher concentrations on the shelf compared to the deep Arctic Ocean. This is primarily due to the low particle flux in the open ocean

  11. Chukchi Borderland | Crustal Complex of the Amerasia Basin, Arctic Ocean

    Science.gov (United States)

    Ilhan, I.; Coakley, B.; Houseknecht, D. W.

    2017-12-01

    In the Arctic Ocean, Chukchi Borderland separates the North Chukchi shelf and Toll deep basins to the west and Canada deep basin to the east. Existing plate reconstructions have attempted to restore this north-striking, fragments of the continental crust to all margins of the Amerasia Basin based on sparse geologic and geophysical measurements. Regional multi-channel seismic reflection and potential field geophysics, and geologic data indicate it is a high standing continental block, requiring special accommodation to create a restorable model of the formation of the Amerasia Basin. The Borderland is composed of the Chukchi Plateau, Northwind Basin, and Northwind Ridge divided by mostly north striking normal faults. These offset the basement and bound a sequence of syn-tectonic sediments. Equivalent strata are, locally, uplifted, deformed and eroded. Seaward dipping reflectors (SDRs) are observed in the juncture between the North Chukchi, Toll basins, and southern Chukchi Plateau underlying a regional angular unconformity. This reveals that this rifted margin was associated with volcanism. An inferred condensed section, which is believed to be Hauterivian-Aptian in age, synchronous with the composite pebble shale and gamma-ray zone of the Alaska North Slope forms the basal sediments in the North Chukchi Basin. Approximately 15 km of post-rift strata onlap the condensed section, SDRs and, in part, the wedge sequence on the Chukchi Plateau from west to east, thinning to the north. These post-Aptian sediments imply that the rifted margin subsided no later than the earliest Cretaceous, providing a plausible time constraint for the inferred pre-Cretaceous rifting in this region. The recognition of SDRs and Hauterivian—Aptian condensed section, and continuity of the Early—Late Cretaceous post-rift strata along the margins of the Borderland, strike variations of the normal faults, absence of observable deformation along the Northwind Escarpment substantially constrain

  12. Sources and burial fluxes of soot black carbon in sediments on the Mackenzie, Chukchi, and Bering Shelves

    Science.gov (United States)

    Yang, Weifeng; Guo, Laodong

    2018-03-01

    Black carbon (BC) has been recognized as a climate forcing and a major component in the global carbon budget. However, studies on BC in the Arctic Ocean remain scarce. We report here variations in the abundance, sources and burial fluxes of sedimentary soot black carbon (soot-BC) in the western Arctic Ocean. The soot-BC contents averaged 1.6 ± 0.3, 0.46 ± 0.04 and 0.56 ± 0.10 mg-C g-1 on the Mackenzie, Chukchi and Bering Shelves, respectively, accounting for 16.6%, 10.2% and 10.4% of the total organic carbon in surface sediment. Temporally, contents of soot-BC remained fairly stable before 1910, but increased rapidly after the 1970s on the Mackenzie Shelf, indicating enhanced source input related to warming. Comparable δ13C signatures of soot-BC (- 24.95‰ to - 24.57‰) to C3 plants pointed to a major biomass source of soot-BC to the Beaufort Sea. Soot-BC showed similar temporal patterns with large fluctuations in the Chukchi/Bering shelf regions, implying the same source terms for soot-BC in these areas. Two events with elevated soot-BC corresponded to a simultaneous increase in biomass combustion and fossil fuel (coal and oil) consumption in Asia. The similar temporal variability in sedimentary soot-BC between the Arctic shelves and Asian lakes and the comparable δ13C values manifested that anthropogenic emission from East Asia was an important source of soot-BC in the western Arctic and subarctic regions. The burial fluxes of soot-BC, estimated from both 137Cs- and 210Pb-derived sedimentation rates, were 2.43 ± 0.42 g-C m-2 yr-1 on the Mackenzie Shelf, representing an efficient soot-BC sink. Soot-BC showed an increase in buried fluxes from 0.56 ± 0.02 g-C m-2 yr-1 during 1963-1986 to 0.88 ± 0.05 g-C m-2 yr-1 after 1986 on the Chukchi Shelf, and from 1.00 ± 0.18 g-C m-2 yr-1 to 2.58 ± 1.70 g-C m-2 yr-1 on the Bering Shelf, which were consistent with recent anthropogenically enhanced BC input observed especially in Asia. Overall, the three Arctic

  13. Contemporary Arctic Sea Level

    Science.gov (United States)

    Cazenave, A. A.

    2017-12-01

    During recent decades, the Arctic region has warmed at a rate about twice the rest of the globe. Sea ice melting is increasing and the Greenland ice sheet is losing mass at an accelerated rate. Arctic warming, decrease in the sea ice cover and fresh water input to the Arctic ocean may eventually impact the Arctic sea level. In this presentation, we review our current knowledge of contemporary Arctic sea level changes. Until the beginning of the 1990s, Arctic sea level variations were essentially deduced from tide gauges located along the Russian and Norwegian coastlines. Since then, high inclination satellite altimetry missions have allowed measuring sea level over a large portion of the Arctic Ocean (up to 80 degree north). Measuring sea level in the Arctic by satellite altimetry is challenging because the presence of sea ice cover limits the full capacity of this technique. However adapted processing of raw altimetric measurements significantly increases the number of valid data, hence the data coverage, from which regional sea level variations can be extracted. Over the altimetry era, positive trend patterns are observed over the Beaufort Gyre and along the east coast of Greenland, while negative trends are reported along the Siberian shelf. On average over the Arctic region covered by satellite altimetry, the rate of sea level rise since 1992 is slightly less than the global mea sea level rate (of about 3 mm per year). On the other hand, the interannual variability is quite significant. Space gravimetry data from the GRACE mission and ocean reanalyses provide information on the mass and steric contributions to sea level, hence on the sea level budget. Budget studies show that regional sea level trends over the Beaufort Gyre and along the eastern coast of Greenland, are essentially due to salinity changes. However, in terms of regional average, the net steric component contributes little to the observed sea level trend. The sea level budget in the Arctic

  14. Multifractal analysis of implied volatility in index options

    Science.gov (United States)

    Oh, GabJin

    2014-06-01

    In this paper, we analyze the statistical and the non-linear properties of the log-variations in implied volatility for the CAC40, DAX and S& P500 daily index options. The price of an index option is generally represented by its implied volatility surface, including its smile and skew properties. We utilize a Lévy process model as the underlying asset to deepen our understanding of the intrinsic property of the implied volatility in the index options and estimate the implied volatility surface. We find that the options pricing models with the exponential Lévy model can reproduce the smile or sneer features of the implied volatility that are observed in real options markets. We study the variation in the implied volatility for at-the-money index call and put options, and we find that the distribution function follows a power-law distribution with an exponent of 3.5 ≤ γ ≤ 4.5. Especially, the variation in the implied volatility exhibits multifractal spectral characteristics, and the global financial crisis has influenced the complexity of the option markets.

  15. Arctic Rabies – A Review

    Directory of Open Access Journals (Sweden)

    Prestrud Pål

    2004-03-01

    Full Text Available Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies including its distribution and epidemiology.

  16. Sediment of a Central European Mountain Lake Implies an Extraterrestrial Impact at the Younger Dryas Onset

    Czech Academy of Sciences Publication Activity Database

    Vondrák, D.; Kletetschka, G.; Hrubá, J.; Nábělek, L.; Procházka, V.; Svitavská-Svobodová, Helena; Bobek, Přemysl; Hořická, Zuzana; Kadlec, Jaroslav; Takáč, M.; Stuchlík, Evžen

    2017-01-01

    Roč. 52, S1 (2017), A373-A373, č. článku 6230. ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /80./. 23.07.2017-28.07.2017, Santa Fe] R&D Projects: GA ČR(CZ) GA17-05935S Institutional support: RVO:67985939 ; RVO:60077344 ; RVO:67985530 Keywords : Younger Dryas * Extraterrestrial Impact * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology; DA - Hydrology ; Limnology (BC-A); DE - Earth Magnetism, Geodesy, Geography (GFU-E) OBOR OECD: Plant sciences, botany

  17. Electrodermal responses to implied versus actual violence on television.

    Science.gov (United States)

    Kalamas, A D; Gruber, M L

    1998-01-01

    The electrodermal response (EDR) of children watching a violent show was measured. Particular attention was paid to the type of violence (actual or implied) that prompted an EDR. In addition, the impact of the auditory component (sounds associated with violence) of the show was evaluated. Implied violent stimuli, such as the villain's face, elicited the strongest EDR. The elements that elicited the weakest responses were the actual violent stimuli, such as stabbing. The background noise and voices of the sound track enhanced the total number of EDRs. The results suggest that implied violence may elicit more fear (as measured by EDRs) than actual violence does and that sounds alone contribute significantly to the emotional response to television violence. One should not, therefore, categorically assume that a show with mostly actual violence evokes less fear than one with mostly implied violence.

  18. Penicillium mycobiota in Arctic subglacial ice

    DEFF Research Database (Denmark)

    Sonjak, S.; Frisvad, Jens Christian; Gunde-Cimerman, N.

    2006-01-01

    , representing on the average half of all isolated strains from all three glaciers. The other most frequently isolated species were P. bialowiezense, P. chrysogenum, P. thomii, P. solitum, P. palitans, P. echinulatum, P. polonicum, P. commune, P. discolor, P. expansum, and new Penicillium species (sp. 1). Twelve...... to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L-1) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum...... more Penicillium species were occasionally isolated. The fungi isolated produced consistent profiles of secondary metabolites, not different from the same Penicillium species from other habitats. This is the first report on the presence of large populations of Penicillium spp. in subglacial sediment...

  19. Arctic security and Norway

    Energy Technology Data Exchange (ETDEWEB)

    Tamnes, Rolf

    2013-03-01

    Global warming is one of the most serious threats facing mankind. Many regions and countries will be affected, and there will be many losers. The earliest and most intense climatic changes are being experienced in the Arctic region. Arctic average temperature has risen at twice the rate of the global average in the past half century. These changes provide an early indication for the world of the environmental and societal significance of global warming. For that reason, the Arctic presents itself as an important scientific laboratory for improving our understanding of the causes and patterns of climate changes. The rapidly rising temperature threatens the Arctic ecosystem, but the human consequences seem to be far less dramatic there than in many other places in the world. According to the U.S. National Intelligence Council, Russia has the potential to gain the most from increasingly temperate weather, because its petroleum reserves become more accessible and because the opening of an Arctic waterway could provide economic and commercial advantages. Norway might also be fortunate. Some years ago, the Financial Times asked: #Left Double Quotation Mark#What should Norway do about the fact that global warming will make their climate more hospitable and enhance their financial situation, even as it inflicts damage on other parts of the world?#Right Double Quotation Mark#(Author)

  20. Correlation Structures of Correlated Binomial Models and Implied Default Distribution

    OpenAIRE

    S. Mori; K. Kitsukawa; M. Hisakado

    2006-01-01

    We show how to analyze and interpret the correlation structures, the conditional expectation values and correlation coefficients of exchangeable Bernoulli random variables. We study implied default distributions for the iTraxx-CJ tranches and some popular probabilistic models, including the Gaussian copula model, Beta binomial distribution model and long-range Ising model. We interpret the differences in their profiles in terms of the correlation structures. The implied default distribution h...

  1. Predicting Agency Rating Migrations with Spread Implied Ratings

    OpenAIRE

    Jianming Kou; Dr Simone Varotto

    2005-01-01

    Investors traditionally rely on credit ratings to price debt instruments. However, rating agencies are known to be prudent in their approach to rating revisions, which results in delayed ratings adjustments to mutating credit conditions. For a large set of eurobonds we derive credit spread implied ratings and compare them with the ratings issued by rating agencies. Our results indicate that spread implied ratings often anticipate future movement of agency ratings and hence could help track cr...

  2. Uniform Bounds for Black--Scholes Implied Volatility

    OpenAIRE

    Tehranchi, Michael Rummine

    2016-01-01

    In this note, Black--Scholes implied volatility is expressed in terms of various optimization problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulas for implied volatility at extreme strikes and/or maturities. the Society for Industrial and Applied Mathematics 10.1137/14095248X

  3. Uniform bounds for Black--Scholes implied volatility

    OpenAIRE

    Tehranchi, Michael R.

    2015-01-01

    In this note, Black--Scholes implied volatility is expressed in terms of various optimisation problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulae for implied volatility at extreme strikes and/or maturities.

  4. Long memory and the relation between implied and realized volatility

    OpenAIRE

    Federico Bandi; Benoit Perron

    2003-01-01

    We argue that the conventional predictive regression between implied volatility (regressor) and realized volatility over the remaining life of the option (regressand) is likely to be a fractional cointegrating relation. Since cointegration is associated with long-run comovements, this finding modifies the usual interpretation of such regression as a study towards assessing option market efficiency (given a certain option pricing model) and/or short-term unbiasedness of implied volatility as a...

  5. Long memory persistence in the factor of Implied volatility dynamics

    OpenAIRE

    Härdle, Wolfgang Karl; Mungo, Julius

    2007-01-01

    The volatility implied by observed market prices as a function of the strike and time to maturity form an Implied Volatility Surface (IV S). Practical applications require reducing the dimension and characterize its dynamics through a small number of factors. Such dimension reduction is summarized by a Dynamic Semiparametric Factor Model (DSFM) that characterizes the IV S itself and their movements across time by a multivariate time series of factor loadings. This paper focuses on investigati...

  6. A Hero in the Friendly Arctic: Deconstructing Vilhjalmur Stefansson's Rhetorical Maneuver

    Directory of Open Access Journals (Sweden)

    Silje Gaupseth

    2012-05-01

    Full Text Available The article deals with Arctic explorer and anthropologist Vilhjalmur Stefansson's self-presentation in the expedition account The Friendly Arctic: The Story of Five Years in Polar Regions (1921, which tells the story of his travels and trials in the Canadian High Arctic in the years between 1913-1918. The account has been considered a key text to Stefansson's Arctic career, and provides a textbook example of his characteristic theory of living off the country in the so-called Eskimo way. Against the background of Stefansson's debated position as Arctic expert and visionary, I ask if it is possible to read the kind of criticism with which Stefansson frequently was met as rooted in some of the narrative aspects of his account. The narrative persona or implied author is a central element in the literature of exploration, as several literary scholars have pointed out. My reading is centred around the implied author of The Friendly Arctic, which I argue must be read in light of the sometimes conflicting roles given to Stefansson as protagonist and narrator in his own story. Close-readings of passages from the account raise the dilemma of how it is possible to present oneself as a hero in an essentially friendly Arctic.

  7. Crustal structure and tectonic model of the Arctic region

    DEFF Research Database (Denmark)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey

    2016-01-01

    We present a new model of the crustal and tectonic structure of the Arctic region north of 60° N latitude, constrained as a part of the international Atlas of Geological Maps of the Circumpolar Arctic under the aegis of the Commission for the Geological Map of the World. The region is largely...... formed by (i) Archean-Paleoproterozoic shields and platforms, (ii) orogenic belts of the Neoproterozoic to the Late Mesozoic ages overlain by platform and basin sediments, (iii) Cenozoic rift structures formed in part as a consequence of seafloor spreading in the North East Atlantic Ocean...... and thickness of the sedimentary cover and presents tectonic regionalization based on 18 major crustal types (oceanic, transitional, and continental) recognized in the Arctic. A 7600. km-long crustal geotransect across the region illustrates the details of its crustal and tectonic structure. We discuss...

  8. Numerical investigations of the fluid flows at deep oceanic and arctic permafrost-associated gas hydrate deposits

    Science.gov (United States)

    Frederick, Jennifer Mary

    older than the host sediment. Old pore fluid age may reflect complex flow patterns, such a fluid focusing, which can cause significant lateral migration as well as regions where downward flow reverses direction and returns toward the seafloor. Longer pathlines can produce pore fluid ages much older than that expected with a one-dimensional compaction model. For steady-state models with geometry representative of Blake Ridge (USA), a well-studied hydrate province, pore fluid ages beneath regions of topography and within fractured zones can be up to 70 Ma old. Results suggest that the measurements of 129-I/127-I reflect a mixture of new and old pore fluid. However, old pore fluid need not originate at great depths. Methane within pore fluids can travel laterally several kilometers, implying an extensive source region around the deposit. Iodine age measurements support the existence of fluid focusing beneath regions of seafloor topography at Blake Ridge, and suggest that the methane source at Blake Ridge is likely shallow. The response of methane hydrate reservoirs to warming is poorly understood. The great depths may protect deep oceanic hydrates from climate change for the time being because transfer of heat by conduction is slow, but warming will eventually be felt albeit in the far future. On the other hand, unique permafrost-associated methane hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Arctic hydrates are thought to be a relict of cold glacial periods, aggrading when sea levels are much lower and shelf sediments are exposed to freezing air temperatures. During interglacial periods, rising sea levels flood the shelf, bringing dramatic warming to the permafrost- and hydrate-bearing sediments. Permafrost-associated methane hydrate deposits have been responding to warming since the last glacial maximum ~18 kaBP as a consequence of these natural glacial cycles. This `experiment,' set into motion by nature itself

  9. Tundra vegetation effects on pan-Arctic albedo

    International Nuclear Information System (INIS)

    Loranty, Michael M; Goetz, Scott J; Beck, Pieter S A

    2011-01-01

    Recent field experiments in tundra ecosystems describe how increased shrub cover reduces winter albedo, and how subsequent changes in surface net radiation lead to altered rates of snowmelt. These findings imply that tundra vegetation change will alter regional energy budgets, but to date the effects have not been documented at regional or greater scales. Using satellite observations and a pan-Arctic vegetation map, we examined the effects of shrub vegetation on albedo across the terrestrial Arctic. We included vegetation classes dominated by low shrubs, dwarf shrubs, tussock-dominated graminoid tundra, and non-tussock graminoid tundra. Each class was further stratified by bioclimate subzones. Low-shrub tundra had higher normalized difference vegetation index values and earlier albedo decline in spring than dwarf-shrub tundra, but for tussock tundra, spring albedo declined earlier than for low-shrub tundra. Our results illustrate how relatively small changes in vegetation properties result in differences in albedo dynamics, regardless of shrub growth, that may lead to differences in net radiation upwards of 50 W m -2 at weekly time scales. Further, our findings imply that changes to the terrestrial Arctic energy budget during this important seasonal transition are under way regardless of whether recent satellite observed productivity trends are the result of shrub expansion. We conclude that a better understanding of changes in vegetation productivity and distribution in Arctic tundra is essential for accurately quantifying and predicting carbon and energy fluxes and associated climate feedbacks.

  10. A History of Coastal Research in the Arctic (Invited)

    Science.gov (United States)

    Walker, H. J.; McGraw, M.

    2009-12-01

    Laboratory in 1947. Although these organizations were broad based, they occasionally had research projects devoted to arctic shorelines. In the USSR, research by Felix Are on shore retreat in the Arctic set the pattern for detail. Because the concentration of people (native as well as non-native) in the Arctic tends to be along the coast(such as Barrow, Alaska and Tuktoyaktuk, Canada) or rivers, some of the earliest research dealt with erosion that threatened settlements. In the process, consideration was given to such factors as sea ice, ground ice and permafrost, sediment type, long-shore drift, tides, wave action, and river discharge. Although there were scattered relevant projects, it was not until the last quarter of the 20th century that teamwork on arctic coastal research began to make its mark. Especially notable are the Russian-German cooperative study of the Lena Delta in 1998 and the International Arctic Science Committee's project on Arctic Coastal Dynamics. The number of detailed studies from such initiatives has increased during the last two decades.

  11. Arctic species resilience

    DEFF Research Database (Denmark)

    Mortensen, Lars O.; Forchhammer, Mads C.; Jeppesen, Erik

    The peak of biological activities in Arctic ecosystems is characterized by a relative short and intense period between the start of snowmelt until the onset of frost. Recent climate changes have induced larger seasonal variation in both timing of snowmelt as well as changes mean temperatures......, an extensive monitoring program has been conducted in the North Eastern Greenland National Park, the Zackenberg Basic. The objective of the program is to provide long time series of data on the natural innate oscillations and plasticity of a High Arctic ecosystem. With offset in the data provided through...

  12. Arctic Climate Variability and Trends from Satellite Observations

    Directory of Open Access Journals (Sweden)

    Xuanji Wang

    2012-01-01

    Full Text Available Arctic climate has been changing rapidly since the 1980s. This work shows distinctly different patterns of change in winter, spring, and summer for cloud fraction and surface temperature. Satellite observations over 1982–2004 have shown that the Arctic has warmed up and become cloudier in spring and summer, but cooled down and become less cloudy in winter. The annual mean surface temperature has increased at a rate of 0.34°C per decade. The decadal rates of cloud fraction trends are −3.4%, 2.3%, and 0.5% in winter, spring, and summer, respectively. Correspondingly, annually averaged surface albedo has decreased at a decadal rate of −3.2%. On the annual average, the trend of cloud forcing at the surface is −2.11 W/m2 per decade, indicating a damping effect on the surface warming by clouds. The decreasing sea ice albedo and surface warming tend to modulate cloud radiative cooling effect in spring and summer. Arctic sea ice has also declined substantially with decadal rates of −8%, −5%, and −15% in sea ice extent, thickness, and volume, respectively. Significant correlations between surface temperature anomalies and climate indices, especially the Arctic Oscillation (AO index, exist over some areas, implying linkages between global climate change and Arctic climate change.

  13. Arctic Terrestrial Biodiversity Monitoring Plan

    DEFF Research Database (Denmark)

    Christensen, Tom; Payne, J.; Doyle, M.

    The Conservation of Arctic Flora and Fauna (CAFF), the biodiversity working group of the Arctic Council, established the Circumpolar Biodiversity Monitoring Program (CBMP) to address the need for coordinated and standardized monitoring of Arctic environments. The CBMP includes an international...... on developing and implementing long-term plans for monitoring the integrity of Arctic biomes: terrestrial, marine, freshwater, and coastal (under development) environments. The CBMP Terrestrial Expert Monitoring Group (CBMP-TEMG) has developed the Arctic Terrestrial Biodiversity Monitoring Plan (CBMP......-Terrestrial Plan/the Plan) as the framework for coordinated, long-term Arctic terrestrial biodiversity monitoring. The goal of the CBMP-Terrestrial Plan is to improve the collective ability of Arctic traditional knowledge (TK) holders, northern communities, and scientists to detect, understand and report on long...

  14. Human-induced Arctic moistening.

    Science.gov (United States)

    Min, Seung-Ki; Zhang, Xuebin; Zwiers, Francis

    2008-04-25

    The Arctic and northern subpolar regions are critical for climate change. Ice-albedo feedback amplifies warming in the Arctic, and fluctuations of regional fresh water inflow to the Arctic Ocean modulate the deep ocean circulation and thus exert a strong global influence. By comparing observations to simulations from 22 coupled climate models, we find influence from anthropogenic greenhouse gases and sulfate aerosols in the space-time pattern of precipitation change over high-latitude land areas north of 55 degrees N during the second half of the 20th century. The human-induced Arctic moistening is consistent with observed increases in Arctic river discharge and freshening of Arctic water masses. This result provides new evidence that human activity has contributed to Arctic hydrological change.

  15. Population viability of Arctic grayling in the Gibbon River, Yellowstone National Park

    Science.gov (United States)

    Steed, Amber C.; Zale, Alexander V.; Koel, Todd M.; Kalinowski, Steven T.

    2010-01-01

    The fluvial Arctic grayling Thymallus arcticus is restricted to less than 5% of its native range in the contiguous United States and was relisted as a category 3 candidate species under the U.S. Endangered Species Act in 2010. Although fluvial Arctic grayling of the lower Gibbon River, Yellowstone National Park, Wyoming, were considered to have been extirpated by 1935, anglers and biologists have continued to report catching low numbers of Arctic grayling in the river. Our goal was to determine whether a viable population of fluvial Arctic grayling persisted in the Gibbon River or whether the fish caught in the river were downstream emigrants from lacustrine populations in headwater lakes. We addressed this goal by determining relative abundances, sources, and evidence for successful spawning of Arctic grayling in the Gibbon River. During 2005 and 2006, Arctic grayling comprised between 0% and 3% of the salmonid catch in riverwide electrofishing (mean Back-calculated lengths at most ages were similar among all fish, and successful spawning within the Gibbon River below the headwater lakes was not documented. Few Arctic grayling adults and no fry were detected in the Gibbon River, implying that a reproducing fluvial population does not exist there. These findings have implications for future Endangered Species Act considerations and management of fluvial Arctic grayling within and outside of Yellowstone National Park. Our comprehensive approach is broadly applicable to the management of sparsely detected aquatic species worldwide.

  16. Conceptualizing delta forms and processes in Arctic coastal environments

    DEFF Research Database (Denmark)

    Bendixen, Mette; Kroon, Aart

    2017-01-01

    Climate warming in the Arctic directly causes two opposite changes in Arctic coastal systems: increased melt-water discharge through rivers induces extra influx of sediments and extended open water season increases wave impact which reworks and erodes the shores. A shoreline change analysis along...... and popped up as hotspots. The Tuapaat delta and Skansen delta showed large progradation rates (1.5 and 7m/yr) and migration of the adjacent barriers and spits. The dynamic behavior at the delta mouths was mainly caused by classic delta channel lobe switching at one delta (Tuapaat), and by a breach...... of the fringing spit at the other delta (Skansen). The longshore and cross-shore transports are responsible for reworking the sediment with a result of migrating delta mouths and adjacent subaqueous mouth bars. Seaward progradation of the deltas is limited due to the steep nature of the bathymetry in Disko Bay...

  17. Coastal sediment dynamics in Spitsbergen

    Science.gov (United States)

    Deloffre, J.; Lafite, R.; Baltzer, A.; Marlin, C.; Delangle, E.; Dethleff, D.; Petit, F.

    2010-12-01

    In arctic knowledge on coastal sediment dynamics and sedimentary processes is limited. The studied area is located in the microtidal Kongsfjorden glacial fjord on the North-western coast of Spitsbergen in the Artic Ocean (79°N). In this area sediment contributions to the coastal zone is provided by small temporary rivers that flows into the fjord. The objectives of this study are to (i) assess the origin and fate of fine-grained particles (sea ice cover on sediment dynamics. The sampling strategy is based on characterization of sediment and SPM (grain-size, X-rays diffraction, SEM images, carbonates and organic matter contents) from the glacier to the coastal zone completed by a bottom-sediment map on the nearshore using side-scan sonar validated with Ekman binge sampling. River inputs (i.e. river plumes) to the coastal zone were punctually followed using CTD (conductivity, temperature, depth and turbidity) profiles. OBS (water level, temperature and turbidity) operating at high-frequency and during at least 1 years (including under sea ice cover) was settled at the mouth of rivers at 10m depth. In the coastal zone the fine-grained sediment deposit is limited to mud patches located at river mouths that originate the piedmont glacier. However a significant amount of sediment originates the coastal glacier located in the eastern part of the fjord via two processes: direct transfer and ice-drop. Results from turbidity measurements show that the sediment dynamics is controlled by river inputs in particular during melting period. During winter sediment resuspension can occurs directly linked to significant wind-events. When the sea ice cover is present (January to April) no sediment dynamics is observed. Sediment processes in the coastal zone of arctic fjords is significant however only a small amount of SPM that originates the river plume settles in the coastal zone; only the coarser material settles at the mouth of the river while the finer one is deposited further

  18. US Implied Volatility as A predictor of International Returns

    Directory of Open Access Journals (Sweden)

    Mehmet F. Dicle

    2017-12-01

    Full Text Available This study provides evidence of the US implied volatility’s e ect on international equitymarkets’ returns. This evidence has two main implications: i investors may find that foreign equityreturns adjusting to US implied volatility may not provide true diversification benefits, and ii foreignequity returns may be predicted using US implied volatility. Our sample includes US volatility index(VIX and major equity indexes in twenty countries for the period between January, 2000 throughJuly, 2017. VIX leads eighteen of the international markets and Granger causes seventeen of themarkets after controlling for the S&P-500 index returns and the 2007/2008 US financial crisis. USinvestors looking to diversify US risk may find that international equities may not provide intendeddiversification benefits. Our evidence provides support for predictability of international equity returnsbased on US volatility.

  19. Correlation Structures of Correlated Binomial Models and Implied Default Distribution

    Science.gov (United States)

    Mori, Shintaro; Kitsukawa, Kenji; Hisakado, Masato

    2008-11-01

    We show how to analyze and interpret the correlation structures, the conditional expectation values and correlation coefficients of exchangeable Bernoulli random variables. We study implied default distributions for the iTraxx-CJ tranches and some popular probabilistic models, including the Gaussian copula model, Beta binomial distribution model and long-range Ising model. We interpret the differences in their profiles in terms of the correlation structures. The implied default distribution has singular correlation structures, reflecting the credit market implications. We point out two possible origins of the singular behavior.

  20. Cryostratigraphy and sedimentology of high-Arctic fjord-valleys

    OpenAIRE

    Gilbert, Graham Lewis

    2018-01-01

    Fjord-valleys, as sediment-filled palaeofjords, are characteristic of formerly glaciated mountainous coastal areas. High-Arctic fjord-valleys commonly host permafrost, but are poorly accessible and hence have drawn relatively little research. The research presented in this thesis combines the methods of cryostratigraphy, clastic sedimentology, sequence stratigraphy, geomorphology and geochronology to investigate the sedimentary infilling, permafrost formation and late Quaternary landscape dev...

  1. Arctic Islands LNG

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, W.

    1977-01-01

    Trans-Canada Pipe Lines Ltd. made a feasibility study of transporting LNG from the High Arctic Islands to a St. Lawrence River Terminal by means of a specially designed and built 125,000 cu m or 165,000 cu m icebreaking LNG tanker. Studies were made of the climatology and of ice conditions, using available statistical data as well as direct surveys in 1974, 1975, and 1976. For on-schedule and unimpeded (unescorted) passage of the LNG carriers at all times of the year, special navigation and communications systems can be made available. Available icebreaking experience, charting for the proposed tanker routes, and tide tables for the Canadian Arctic were surveyed. Preliminary design of a proposed Arctic LNG icebreaker tanker, including containment system, reliquefaction of boiloff, speed, power, number of trips for 345 day/yr operation, and liquefaction and regasification facilities are discussed. The use of a minimum of three Arctic Class 10 ships would enable delivery of volumes of natural gas averaging 11.3 million cu m/day over a period of a year to Canadian markets. The concept appears to be technically feasible with existing basic technology.

  2. Disparities in Arctic Health

    Centers for Disease Control (CDC) Podcasts

    Life at the top of the globe is drastically different. Harsh climate devoid of sunlight part of the year, pockets of extreme poverty, and lack of physical infrastructure interfere with healthcare and public health services. Learn about the challenges of people in the Arctic and how research and the International Polar Year address them.

  3. The Arctic Circle

    Science.gov (United States)

    McDonald, Siobhan

    2016-04-01

    My name is Siobhan McDonald. I am a visual artist living and working in Dublin. My studio is based in The School of Science at University College Dublin where I was Artist in Residence 2013-2015. A fascination with time and the changeable nature of landmass has led to ongoing conversations with scientists and research institutions across the interweaving disciplines of botany, biology and geology. I am developing a body of work following a recent research trip to the North Pole where I studied the disappearing landscape of the Arctic. Prompted by my experience of the Arctic shelf receding, this new work addresses issues of the instability of the earth's materiality. The work is grounded in an investigation of material processes, exploring the dynamic forces that transform matter and energy. This project combines art and science in a fascinating exploration of one of the Earth's last relatively untouched wilderness areas - the High Arctic to bring audiences on journeys to both real and artistically re-imagined Arctic spaces. CRYSTALLINE'S pivotal process is collaboration: with The European Space Agency; curator Helen Carey; palaeontologist Prof. Jenny McElwain, UCD; and with composer Irene Buckley. CRYSTALLINE explores our desire to make corporeal contact with geological phenomena in Polar Regions. From January 2016, in my collaboration with Jenny McElwain, I will focus on the study of plants and atmospheres from the Arctic regions as far back as 400 million years ago, to explore the essential 'nature' that, invisible to the eye, acts as imaginary portholes into other times. This work will be informed by my arctic tracings of sounds and images recorded in the glaciers of this disappearing frozen landscape. In doing so, the urgencies around the tipping of natural balances in this fragile region will be revealed. The final work will emerge from my forthcoming residency at the ESA in spring 2016. Here I will conduct a series of workshops in ESA Madrid to work with

  4. Genomics of Arctic cod

    Science.gov (United States)

    Wilson, Robert E.; Sage, George K.; Sonsthagen, Sarah A.; Gravley, Megan C.; Menning, Damian; Talbot, Sandra L.

    2017-01-01

    The Arctic cod (Boreogadus saida) is an abundant marine fish that plays a vital role in the marine food web. To better understand the population genetic structure and the role of natural selection acting on the maternally-inherited mitochondrial genome (mitogenome), a molecule often associated with adaptations to temperature, we analyzed genetic data collected from 11 biparentally-inherited nuclear microsatellite DNA loci and nucleotide sequence data from from the mitochondrial DNA (mtDNA) cytochrome b (cytb) gene and, for a subset of individuals, the entire mitogenome. In addition, due to potential of species misidentification with morphologically similar Polar cod (Arctogadus glacialis), we used ddRAD-Seq data to determine the level of divergence between species and identify species-specific markers. Based on the findings presented here, Arctic cod across the Pacific Arctic (Bering, Chukchi, and Beaufort Seas) comprise a single panmictic population with high genetic diversity compared to other gadids. High genetic diversity was indicated across all 13 protein-coding genes in the mitogenome. In addition, we found moderate levels of genetic diversity in the nuclear microsatellite loci, with highest diversity found in the Chukchi Sea. Our analyses of markers from both marker classes (nuclear microsatellite fragment data and mtDNA cytb sequence data) failed to uncover a signal of microgeographic genetic structure within Arctic cod across the three regions, within the Alaskan Beaufort Sea, or between near-shore or offshore habitats. Further, data from a subset of mitogenomes revealed no genetic differentiation between Bering, Chukchi, and Beaufort seas populations for Arctic cod, Saffron cod (Eleginus gracilis), or Walleye pollock (Gadus chalcogrammus). However, we uncovered significant differences in the distribution of microsatellite alleles between the southern Chukchi and central and eastern Beaufort Sea samples of Arctic cod. Finally, using ddRAD-Seq data, we

  5. Tachyons imply the existence of a privileged frame

    Energy Technology Data Exchange (ETDEWEB)

    Sjoedin, T.; Heylighen, F.

    1985-12-16

    It is shown that the existence of faster-than-light signals (tachyons) would imply the existence (and detectability) of a privileged inertial frame and that one can avoid all problems with reversed-time order only by using absolute synchronization instead of the standard one. The connection between these results and the EPR-paradox is discussed.

  6. Comprehending Implied Meaning in English as a Foreign Language

    Science.gov (United States)

    Taguchi, Naoko

    2005-01-01

    This study investigated whether second language (L2) proficiency affects pragmatic comprehension, namely the ability to comprehend implied meaning in spoken dialogues, in terms of accuracy and speed of comprehension. Participants included 46 native English speakers at a U.S. university and 160 Japanese students of English in a college in Japan who…

  7. Estimating implied rates of discount in healthcare decision-making.

    Science.gov (United States)

    West, R R; McNabb, R; Thompson, A G H; Sheldon, T A; Grimley Evans, J

    2003-01-01

    To consider whether implied rates of discounting from the perspectives of individual and society differ, and whether implied rates of discounting in health differ from those implied in choices involving finance or "goods". The study comprised first a review of economics, health economics and social science literature and then an empirical estimate of implied rates of discounting in four fields: personal financial, personal health, public financial and public health, in representative samples of the public and of healthcare professionals. Samples were drawn in the former county and health authority district of South Glamorgan, Wales. The public sample was a representative random sample of men and women, aged over 18 years and drawn from electoral registers. The health professional sample was drawn at random with the cooperation of professional leads to include doctors, nurses, professions allied to medicine, public health, planners and administrators. The literature review revealed few empirical studies in representative samples of the population, few direct comparisons of public with private decision-making and few direct comparisons of health with financial discounting. Implied rates of discounting varied widely and studies suggested that discount rates are higher the smaller the value of the outcome and the shorter the period considered. The relationship between implied discount rates and personal attributes was mixed, possibly reflecting the limited nature of the samples. Although there were few direct comparisons, some studies found that individuals apply different rates of discount to social compared with private comparisons and health compared with financial. The present study also found a wide range of implied discount rates, with little systematic effect of age, gender, educational level or long-term illness. There was evidence, in both samples, that people chose a lower rate of discount in comparisons made on behalf of society than in comparisons made for

  8. Intuitive understanding of nonlocality as implied by quantum theory

    International Nuclear Information System (INIS)

    Bohm, D.G.; Hiley, B.J.

    1975-01-01

    The fact is brought out that the essential new quality implied by the quantum theory is nonlocality; i.e., that a system cannot be analyzed into parts whose basic properties do not depend on the state of the whole system. This is done in terms of the causal interpretation of the quantum theory, proposed by one of us (D.B.) in 2952, involving the introduction of the ''quantum potential.'' It is shown that this approach implies a new universal type of description, in which the standard or canonical form is always supersystem-system-subsystem; and this leads to the radically new notion of unbroken wholeness of the entire universe. Finally, some of the implications of extending these notions to the relativity domain, and in so doing, a novel concept of time, in terms of which relativity and quantum theory may eventually be brought together, is indicated

  9. Implied Movement in Static Images Reveals Biological Timing Processing

    Directory of Open Access Journals (Sweden)

    Francisco Carlos Nather

    2015-08-01

    Full Text Available Visual perception is adapted toward a better understanding of our own movements than those of non-conspecifics. The present study determined whether time perception is affected by pictures of different species by considering the evolutionary scale. Static (“S” and implied movement (“M” images of a dog, cheetah, chimpanzee, and man were presented to undergraduate students. S and M images of the same species were presented in random order or one after the other (S-M or M-S for two groups of participants. Movement, Velocity, and Arousal semantic scales were used to characterize some properties of the images. Implied movement affected time perception, in which M images were overestimated. The results are discussed in terms of visual motion perception related to biological timing processing that could be established early in terms of the adaptation of humankind to the environment.

  10. Language comprehenders retain implied shape and orientation of objects.

    Science.gov (United States)

    Pecher, Diane; van Dantzig, Saskia; Zwaan, Rolf A; Zeelenberg, René

    2009-06-01

    According to theories of embodied cognition, language comprehenders simulate sensorimotor experiences to represent the meaning of what they read. Previous studies have shown that picture recognition is better if the object in the picture matches the orientation or shape implied by a preceding sentence. In order to test whether strategic imagery may explain previous findings, language comprehenders first read a list of sentences in which objects were mentioned. Only once the complete list had been read was recognition memory tested with pictures. Recognition performance was better if the orientation or shape of the object matched that implied by the sentence, both immediately after reading the complete list of sentences and after a 45-min delay. These results suggest that previously found match effects were not due to strategic imagery and show that details of sensorimotor simulations are retained over longer periods.

  11. Implied Materiality and Material Disclosures of Credit Ratings

    OpenAIRE

    Eccles, Robert G; Youmans, Timothy John

    2015-01-01

    This first of three papers in our series on materiality in credit ratings will examine the materiality of credit ratings from an “implied materiality” and governance disclosure perspective. In the second paper, we will explore the materiality of environmental, social, and governance (ESG) factors in credit ratings’ methodologies and introduce the concept of “layered materiality.” In the third paper, we will evaluate current and potential credit rating agency (CRA) business models based on our...

  12. On return rate implied by behavioural present value

    OpenAIRE

    Piasecki, Krzysztof

    2013-01-01

    The future value of a security is described as a random variable. Distribution of this random variable is the formal image of risk uncertainty. On the other side, any present value is defined as a value equivalent to the given future value. This equivalence relationship is a subjective. Thus follows, that present value is described as a fuzzy number, which is depend on the investor's susceptibility to behavioural factors. All above reasons imply, that return rate is given as a fuzzy probabili...

  13. Wave function collapse implies divergence of average displacement

    OpenAIRE

    Marchewka, A.; Schuss, Z.

    2005-01-01

    We show that propagating a truncated discontinuous wave function by Schr\\"odinger's equation, as asserted by the collapse axiom, gives rise to non-existence of the average displacement of the particle on the line. It also implies that there is no Zeno effect. On the other hand, if the truncation is done so that the reduced wave function is continuous, the average coordinate is finite and there is a Zeno effect. Therefore the collapse axiom of measurement needs to be revised.

  14. TEMPORAL INSENSITIVITY OF PVWTP AND IMPLIED DISCOUNT RATES IN CVM

    OpenAIRE

    Kim, Sooil; Haab, Timothy C.

    2003-01-01

    The sensitivity of WTP is tested in terms of the present value and the implied discount rates are derived by varying the length of benefit and the temporal payment schedules. Results show that holding the length of the project constant, the present value of willingness to pay does not vary significantly across payment schemes (one time payment, versus life of the project, versus perpetuity). Heteroskedasticity of error term over payment schemes fails to be accepted. Holding the payment scheme...

  15. Arctic industrial activities compilation

    International Nuclear Information System (INIS)

    1991-01-01

    Most industrial activities in the Beaufort Sea region are directly or indirectly associated with the search for oil and gas. Activities in marine areas include dredging, drilling, seismic and sounding surveys, island/camp maintenance, vessel movements, helicoptor and fixed-wind flights, and ice-breaking. This inventory contains a summary of chemical usage at 119 offshore drilling locations in the Beaufort Sea, Arctic Islands and Davis Straight of the Canadian Arctic between 1973 and 1987. Data are graphically displayed for evaluating patterns of drill waste discharge in the three offshore drilling areas. These displays include a comparison of data obtained from tour sheets and well history records, summaries of drilling mud chemicals used by year, well and oil company, frequency of wells drilled as a function of water depth, and offshore drilling activity by year, company, and platform. 21 refs., 104 figs., 2 tabs

  16. Cryolithozone of Western Arctic shelf of Russia

    Science.gov (United States)

    Kholmyanskii, Mikhail; Vladimirov, Maksim; Snopova, Ekaterina; Kartashev, Aleksandr

    2017-04-01

    We propose a new original version of the structure of the cryolithozone of west Arctic seas of Russia. In contrast to variants of construction of sections and maps based on thermodynamic modeling, the authors have used electrometric, seismic, and thermal data including their own profile measurements by near-field transient electromagnetic technique and seismic profile observations by reflection method. As a result, we defined the spatial characteristics of cryolithozone and managed to differentiate it to several layers, different both in structure and formation time. We confirmed once again that the spatial boundary of cryolithozone, type and thickness of permafrost, chilled rocks and thawed ground are primarily determined by tectonic and oceanographic regimes of the Arctic Ocean and adjacent land in different geological epochs. Permafrost formed on the land in times of cold weather, turn to submarine during flooding and overlap, in the case of the sea transgression, by marine sediments accumulating in the period of warming. We have been able to establish a clear link between the permafrost thickness and the geomorphological structure of the area. This can be explained by the distribution of thermodynamic flows that change the temperature state of previously formed permafrost rocks. Formation in the outer parts of the shelf which took place at ancient conversion stage can be characterized by the structure: • permafrost table - consists of rocks, where the sea water with a temperature below 0 °C has replaced the melted ice; • middle horizon - composed of undisturbed rocks, and the rocks chilled through the lower sieving underlay; As a result of the interpretation and analysis of all the available data, the authors created a map of types of cryolithozone of the Western Arctic shelf of Russia. The following distribution areas are marked on the map: • single-layer cryolithozone (composed of sediments upper Pleistocene and Holocene); • monosyllabic relict

  17. Seasonal variability in Arctic temperatures during the early Eocene

    Science.gov (United States)

    Eberle, J. J.; Fricke, H. C.; Humphrey, J.; Hackett, L.; Newbrey, M.; Hutchison, H.

    2009-12-01

    As a deep time analog for today’s rapidly warming Arctic region, early Eocene (~53 Ma) rocks on Ellesmere Island, Arctic Canada (~79° N.) preserve evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions that at present, quantitative estimates of Eocene Arctic climate are rare. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we provide estimates of early Eocene Arctic temperature, including mean annual temperature (MAT) of ~ 8° C, mean annual range in temperature (MART) of ~ 16.5° C, warm month mean temperature (WMMT) of 16 - 19° C, and cold month mean temperature (CMMT) of 0 - 1° C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, unusually high estimates of early Eocene Arctic MAT and sea surface temperature (SST) by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and marine Crenarchaeota fall within our range of WMMT, suggesting a bias towards summer values. Consequently, caution should be taken when using these methods to infer MAT and SST that, in turn, are used to constrain climate models. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although in both of these reptiles, past temperature tolerances were greater than in their living descendants.

  18. Disparities in Arctic Health

    Centers for Disease Control (CDC) Podcasts

    2008-02-04

    Life at the top of the globe is drastically different. Harsh climate devoid of sunlight part of the year, pockets of extreme poverty, and lack of physical infrastructure interfere with healthcare and public health services. Learn about the challenges of people in the Arctic and how research and the International Polar Year address them.  Created: 2/4/2008 by Emerging Infectious Diseases.   Date Released: 2/20/2008.

  19. Climate sensitivity to Arctic seaway restriction during the early Paleogene

    Science.gov (United States)

    Roberts, Christopher D.; LeGrande, Allegra N.; Tripati, Aradhna K.

    2009-09-01

    The opening and closing of ocean gateways affects the global distribution of heat, salt, and moisture, potentially driving climatic change on regional to global scales. Between 65 and 45 million years ago (Ma), during the early Paleogene, exchange between the Arctic and global oceans occurred through two narrow and shallow seaways, the Greenland-Norway seaway and the Turgai Strait. Sediments from the Arctic Ocean suggest that, during this interval, the surface ocean was warm, brackish, and episodically enabled the freshwater fern Azolla to bloom. The precise mechanisms responsible for the development of these conditions in the Paleogene Arctic remain uncertain. Here we show results from an isotope-enabled, atmosphere-ocean general circulation model, which indicate that Northern Hemisphere climate would have been very sensitive to the degree of oceanic exchange through the Arctic seaways. We also present modelled estimates of seawater and calcite δ18O for the Paleogene. By restricting these seaways, we simulate freshening of the surface Arctic Ocean to ~ 6 psu and warming of sea-surface temperatures by 2 °C in the North Atlantic and 5-10 °C in the Labrador Sea. Our results may help explain the occurrence of low-salinity tolerant taxa in the Arctic Ocean during the Eocene and provide a mechanism for enhanced warmth in the north western Atlantic. We propose that the formation of a volcanic land-bridge between Greenland and Europe could have caused increased ocean convection and warming of intermediate waters in the Atlantic. If true, this result is consistent with the theory that bathymetry changes may have caused thermal destabilisation of methane clathrates and supports a tectonic trigger hypothesis for the Paleocene Eocene Thermal Maximum (PETM).

  20. Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas

    NARCIS (Netherlands)

    Barke, J.; Burgh, A.H.P. van der; Konijnenburg-van Cittert, J.H.A. van; Collinson, M.E.; Pearce, M.A.; Bujak, J.; Heilman-Clausen, C.; Lotter, A.F.; Speelman, E.N.; Kempen, M.M.L. van; Reichart, G.-J.; Brinkhuis, H.

    2012-01-01

    For a short time interval (c. 1.2 Myr) during the early middle Eocene (~ 49 Myr), the central Arctic Ocean was episodically densely covered by the freshwater fern Azolla, implying sustained freshening of surface waters. Coeval Azolla fossils in neighboring Nordic seas were thought to have been

  1. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean.

    Science.gov (United States)

    Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-20

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (Ocean (79-90 °N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85 °N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  2. Comparative analysis of marine paleogene sections and biota from West Siberia and the Arctic Region

    Science.gov (United States)

    Akhmet'ev, M. A.; Zaporozhets, N. I.; Iakovleva, A. I.; Aleksandrova, G. N.; Beniamovsky, V. N.; Oreshkina, T. V.; Gnibidenko, Z. N.; Dolya, Zh. A.

    2010-12-01

    The analysis of the main biospheric events that took place in West Siberia and the Arctic region during the Early Paleogene revealed the paleogeographic and paleobiogeographic unity of marine sedimentation basins and close biogeographic relations between their separate parts. Most biotic and abiotic events of the first half of the Paleogene in the Arctic region and West Siberia were synchronous, unidirectional, and interrelated. Shelf settings, sedimentation breaks, and microfaunal assemblages characteristic of these basins during the Paleogene are compared. The comparative analysis primarily concerned events of the Paleocene-Eocene thermal maximum (PETM) and beds with Azolla (aquatic fern). The formation of the Eocene Azolla Beds in the Arctic region and West Siberia was asynchronous, although it proceeded in line with a common scenario related to the development of a system of estuarine-type currents in a sea basin partly isolated from the World Ocean.

  3. Interpreting the implied meridional oceanic energy transport in AMIP

    International Nuclear Information System (INIS)

    Randall, D.A.; Gleckler, P.J.

    1993-09-01

    The Atmospheric Model Intercomparison Project (AMIP) was outlined in Paper No. CLIM VAR 2.3 (entitled open-quote The validation of ocean surface heat fluxes in AMIP') of these proceedings. Preliminary results of AMIP subproject No. 5 were also summarized. In particular, zonally averaged ocean surface heat fluxes resulting from various AMIP simulations were intercompared, and to the extent possible they were validated with uncertainties in observationally-based estimates of surface heat fluxes. The intercomparison is continued in this paper by examining the Oceanic Meridional Energy Transport (OMET) implied by the net surface heat fluxes of the AMIP simulations. As with the surface heat fluxes of the AMIP simulations. As with the surface heat fluxes, the perspective here will be very cursory. The annual mean implied ocean heat transport can be estimated by integrating the zonally averaged net ocean surface heat flux, N sfc , from one pole to the other. In AGCM simulations (and perhaps reality), the global mean N sfc is typically not in exact balance when averaged over one or more years. Because of this, an important assumption must be made about changes in the distribution of energy in the oceans. Otherwise, the integration will yield a non-zero transport at the endpoint of integration (pole) which is not physically realistic. Here the authors will only look at 10-year means of the AMIP runs, and for simplicity they assume that any long term imbalance in the global averaged N sfc will be sequestered (or released) over the global ocean. Tests have demonstrated that the treatment of how the global average energy imbalance is assumed to be distributed is important, especially when the long term imbalances are in excess of 10 W m -2 . However, this has not had a substantial impact on the qualitative features of the implied heat transport of the AMIP simulations examined thus far

  4. Implied reading direction and prioritization of letter encoding.

    Science.gov (United States)

    Holcombe, Alex O; Nguyen, Elizabeth H L; Goodbourn, Patrick T

    2017-10-01

    Capacity limits hinder processing of multiple stimuli, contributing to poorer performance for identifying two briefly presented letters than for identifying a single letter. Higher accuracy is typically found for identifying the letter on the left, which has been attributed to a right-hemisphere dominance for selective attention. Here, we use rapid serial visual presentation (RSVP) of letters in two locations at once. The letters to be identified are simultaneous and cued by rings. In the first experiment, we manipulated implied reading direction by rotating or mirror-reversing the letters to face to the left rather than to the right. The left-side performance advantage was eliminated. In the second experiment, letters were positioned above and below fixation, oriented such that they appeared to face downward (90° clockwise rotation) or upward (90° counterclockwise rotation). Again consistent with an effect of implied reading direction, performance was better for the top position in the downward condition, but not in the upward condition. In both experiments, mixture modeling of participants' report errors revealed that attentional sampling from the two locations was approximately simultaneous, ruling out the theory that the letter on one side was processed first, followed by a shift of attention to sample the other letter. Thus, the orientation of the letters apparently controls not when the letters are sampled from the scene, but rather the dynamics of a subsequent process, such as tokenization or memory consolidation. Implied reading direction appears to determine the letter prioritized at a high-level processing bottleneck. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  5. Noninvadability implies noncoexistence for a class of cancellative systems

    Czech Academy of Sciences Publication Activity Database

    Swart, Jan M.

    2013-01-01

    Roč. 18, č. 38 (2013), s. 1-12 ISSN 1083-589X R&D Projects: GA ČR GAP201/10/0752 Institutional support: RVO:67985556 Keywords : cancellative system * interface tightness * duality * coexistence * Neuhauser-Pacala model * affine voter model * rebellious voter model * balancing selection * branching * annihilation * parity preservation Subject RIV: BA - General Mathematics Impact factor: 0.627, year: 2013 http://library.utia.cas.cz/separaty/2013/SI/swart-noninvadability implies noncoexistence for a class of cancellative systems.pdf

  6. Likelihood ratio decisions in memory: three implied regularities.

    Science.gov (United States)

    Glanzer, Murray; Hilford, Andrew; Maloney, Laurence T

    2009-06-01

    We analyze four general signal detection models for recognition memory that differ in their distributional assumptions. Our analyses show that a basic assumption of signal detection theory, the likelihood ratio decision axis, implies three regularities in recognition memory: (1) the mirror effect, (2) the variance effect, and (3) the z-ROC length effect. For each model, we present the equations that produce the three regularities and show, in computed examples, how they do so. We then show that the regularities appear in data from a range of recognition studies. The analyses and data in our study support the following generalization: Individuals make efficient recognition decisions on the basis of likelihood ratios.

  7. Faster than light motion does not imply time travel

    International Nuclear Information System (INIS)

    Andréka, Hajnal; Madarász, Judit X; Németi, István; Székely, Gergely; Stannett, Mike

    2014-01-01

    Seeing the many examples in the literature of causality violations based on faster than light (FTL) signals one naturally thinks that FTL motion leads inevitably to the possibility of time travel. We show that this logical inference is invalid by demonstrating a model, based on (3+1)-dimensional Minkowski spacetime, in which FTL motion is permitted (in every direction without any limitation on speed) yet which does not admit time travel. Moreover, the Principle of Relativity is true in this model in the sense that all observers are equivalent. In short, FTL motion does not imply time travel after all. (paper)

  8. Biodiversity of arctic marine fishes

    DEFF Research Database (Denmark)

    Mecklenburg, Catherine W.; Møller, Peter Rask; Steinke, Dirk

    2011-01-01

    Taxonomic and distributional information on each fish species found in arctic marine waters is reviewed, and a list of families and species with commentary on distributional records is presented. The list incorporates results from examination of museum collections of arctic marine fishes dating b...

  9. Mining in the European Arctic

    NARCIS (Netherlands)

    van Dam, Kim; Scheepstra, Annette; Gille, Johan; Stępień, Adam; Koivurova, Timo

    The European Arctic is currently experiencing an upsurge in mining activities, but future developments will be highly sensitive to mineral price fluctuations. The EU is a major consumer and importer of Arctic raw materials. As the EU is concerned about the security of supply, it encourages domestic

  10. Orbitally forced Azolla blooms and Middle Eocene Arctic hydrology: Clues from palynology

    NARCIS (Netherlands)

    Barke, J.; Abels, H.A.; Sangiorgi, F.; Greenwood, D.R.; Sweet, A.R.; Donders, T.; Reichart, G.-J.; Lotter, A.F.; Brinkhuis, H.

    2011-01-01

    The high abundances and cyclic distribution of remains of the freshwater fern Azolla in early-Middle Eocene sediments from the Arctic Ocean have previously been related to episodic surface-water freshening, which was speculated to be orbitally modulated. Our integrated palynological and

  11. Orbitally forced Azolla blooms And Middle Eocene Arctic hydrology: Clues from palynology

    NARCIS (Netherlands)

    Barke, J.; Abels, H.A.; Sangiorgi, F.; Greenwood, D.R.; Sweet, A.R.; Donders, T.; Reichart, G.-J.; Lotter, A.F.; Brinkhuis, H.

    2011-01-01

    The high abundances and cyclic distribution of remains of the freshwater fern Azolla in early-Middle Eocene sediments from the Arctic Ocean have previously been related to episodic surface-water freshening, which was speculated to be orbitally modulated. Our integrated palynological and

  12. Changes in Ocean Circulation with an Ice-Free Arctic: Reconstructing Early Holocene Arctic Ocean Circulation Using Geochemical Signals from Individual Neogloboquadrina pachyderma (sinistral) Shells

    Science.gov (United States)

    Livsey, C.; Spero, H. J.; Kozdon, R.

    2016-12-01

    The impacts of sea ice decrease and consequent hydrologic changes in the Arctic Ocean will be experienced globally as ocean and atmospheric temperatures continue to rise, though it is not evident to what extent. Understanding the structure of the Arctic water column during the early/mid Holocene sea ice minimum ( 6-10 kya), a post-glacial analogue of a seasonally ice-free Arctic, will help us to predict what the changes we can expect as the Earth warms over the next century. Neogloboquadrina pachyderma (sinistral; Nps) is a species of planktonic foraminifera that dominates assemblages in the polar oceans. This species grows its chambers (ontogenetic calcite) in the surface waters and subsequently descends through the water column to below the mixed layer where it quickly adds a thick crust of calcite (Kohfeld et al., 1996). Therefore, geochemical signals from both the surface waters and sub-mixed layer depths are captured within single Nps shells. We were able to target ion mass spectrometry (SIMS), therefore capturing signals from both the ontogenetic and crust calcite in single Nps shells. This data was combined with laser ablation- inductively coupled mass spectrometry (LA-ICPMS) Mg/Ca profiles of trace metals through the two layers of calcite of the same shells, to determine the thermal structure of the water column. Combining δ18O, temperature, and salinity gradients from locations across the Arctic basin allow us to reconstruct the hydrography of the early Holocene Arctic sea ice minimum. These results will be compared with modern Arctic water column characteristics in order to develop a conceptual model of Arctic Ocean oceanographic change due to global warming. Kohfeld, K.E., Fairbanks, R.G., Smith, S.L., Walsh, I.D., 1996. Neogloboquadrina pachyderma(sinistral coiling) as paleoceanographic tracers in polar oceans: Evidence from northeast water polynya plankton tows, sediment traps, and surface sediments. Paleoceanography 11, 679-699.

  13. Acquiring Marine Data in the Canada Basin, Arctic Ocean

    Science.gov (United States)

    Hutchinson, Deborah R.; Jackson, H. Ruth; Shimeld, John W.; Chapman, C. Borden; Childs, Jonathan R.; Funck, Thomas; Rowland, Robert W.

    2009-06-01

    Despite the record minimum ice extent in the Arctic Ocean for the past 2 years, collecting geophysical data with towed sensors in ice-covered regions continues to pose enormous challenges. Significant parts of the Canada Basin in the western Arctic Ocean have remained largely unmapped because thick multiyear ice has limited access even by research vessels strengthened against ice [Jackson et al., 1990]. Because of the resulting paucity of data, the western Arctic Ocean is one of the few areas of ocean in the world where major controversies still exist with respect to its origin and tectonic evolution [Grantz et al., 1990; Lawver and Scotese, 1990; Lane, 1997; Miller et al., 2006]. This article describes the logistical challenges and initial data sets from geophysical seismic reflection, seismic refraction, and hydrographic surveys in the Canada Basin conducted by scientists with U.S. and Canadian government agencies (Figure 1a) to fulfill the requirements of the United Nations Convention on the Law of the Sea to determine sediment thickness, geological origin, and basin evolution in this unexplored part of the world. Some of these data were collected using a single ship, but the heaviest ice conditions necessitated using two icebreakers, similar to other recent Arctic surveys [e.g., Jokat, 2003].

  14. Arctic Nuclear Waste Assessment Program

    International Nuclear Information System (INIS)

    Edson, R.

    1995-01-01

    The Arctic Nuclear Waste Assessment Program (ANWAP) was initiated in 1993 as a result of US congressional concern over the disposal of nuclear materials by the former Soviet Union into the Arctic marine environment. The program is comprised of appr. 70 different projects. To date appr. ten percent of the funds has gone to Russian institutions for research and logistical support. The collaboration also include the IAEA International Arctic Seas Assessment Program. The major conclusion from the research to date is that the largest signals for region-wide radionuclide contamination in the Arctic marine environment appear to arise from the following: 1) atmospheric testing of nuclear weapons, a practice that has been discontinued; 2) nuclear fuel reprocessing wastes carried in the Arctic from reprocessing facilities in Western Europe, and 3) accidents such as Chernobyl and the 1957 explosion at Chelyabinsk-65

  15. Arctic-HYCOS: a Large Sample observing system for estimating freshwater fluxes in the drainage basin of the Arctic Ocean

    Science.gov (United States)

    Pietroniro, Al; Korhonen, Johanna; Looser, Ulrich; Hardardóttir, Jórunn; Johnsrud, Morten; Vuglinsky, Valery; Gustafsson, David; Lins, Harry F.; Conaway, Jeffrey S.; Lammers, Richard; Stewart, Bruce; Abrate, Tommaso; Pilon, Paul; Sighomnou, Daniel; Arheimer, Berit

    2015-04-01

    The Arctic region is an important regulating component of the global climate system, and is also experiencing a considerable change during recent decades. More than 10% of world's river-runoff flows to the Arctic Ocean and there is evidence of changes in its fresh-water balance. However, about 30% of the Arctic basin is still ungauged, with differing monitoring practices and data availability from the countries in the region. A consistent system for monitoring and sharing of hydrological information throughout the Arctic region is thus of highest interest for further studies and monitoring of the freshwater flux to the Arctic Ocean. The purpose of the Arctic-HYCOS project is to allow for collection and sharing of hydrological data. Preliminary 616 stations were identified with long-term daily discharge data available, and around 250 of these already provide online available data in near real time. This large sample will be used in the following scientific analysis: 1) to evaluate freshwater flux to the Arctic Ocean and Seas, 2) to monitor changes and enhance understanding of the hydrological regime and 3) to estimate flows in ungauged regions and develop models for enhanced hydrological prediction in the Arctic region. The project is intended as a component of the WMO (World Meteorological Organization) WHYCOS (World Hydrological Cycle Observing System) initiative, covering the area of the expansive transnational Arctic basin with participation from Canada, Denmark, Finland, Iceland, Norway, Russian Federation, Sweden and United States of America. The overall objective is to regularly collect, manage and share high quality data from a defined basic network of hydrological stations in the Arctic basin. The project focus on collecting data on discharge and possibly sediment transport and temperature. Data should be provisional in near-real time if available, whereas time-series of historical data should be provided once quality assurance has been completed. The

  16. Implied Reading in the Unforgettable Stories of Language Learners

    Directory of Open Access Journals (Sweden)

    Feryal ÇUBUKÇU

    2017-09-01

    Full Text Available Iser is literary theoretician and co-founder of the Constance School of Reception Aesthetics, professor Emeritus of English and Comparative Literature at the University of Constance and the University of California, Irvine. When Iser died in 2007 in his eighty-first year, he was one of the most widely known literary theoreticians in the world. His “implied reading” theory claims that texts can themselves also awaken false expectations, alternately bringing about surprise, joy and frustration, which can be the enlargement of experience. The indeterminacy of the text might yield different responses from different readers. To prove that each implied reading is based on the schemata of the readers, this study aims at analysing the stories told by language learners of Turkish who come from 20 countries and whose ages vary between 18-32. The participants are 65 undergraduate and graduate university students, from African, Asian and Balkan countries, who upon watching “Cinderella” were asked to write about the unforgettable folk story or fairy tale. When their stories are item analysed, the results show that the schematas of the learners shape the way they choose and recount the stories. Leraners of Turkish fill in the gaps throughout the story, form a meaningful bond by pulling information from it, participating in a reciprocal relationship, creating and deriving meaning in an extravaganza of interpretation.

  17. AMAP Assessment 2013: Arctic Ocean acidification

    Science.gov (United States)

    2013-01-01

    This assessment report presents the results of the 2013 AMAP Assessment of Arctic Ocean Acidification (AOA). This is the first such assessment dealing with AOA from an Arctic-wide perspective, and complements several assessments that AMAP has delivered over the past ten years concerning the effects of climate change on Arctic ecosystems and people. The Arctic Monitoring and Assessment Programme (AMAP) is a group working under the Arctic Council. The Arctic Council Ministers have requested AMAP to: - produce integrated assessment reports on the status and trends of the conditions of the Arctic ecosystems;

  18. Cesium in Arctic char lakes - effects of the Chernobyl accident

    International Nuclear Information System (INIS)

    Hammar, J.; Notter, M.; Neumann, G.

    1991-01-01

    Fallout radiocesium from the Chernobyl accident caused extensive contamination in a region of previously well studied alpine lake ecosystems in northern Sweden. Levels of Cs-137 in the barren catchment basins reached 20-50 kBq/m 2 during 1986. The distribution, pathways and major transport mechanisms of radiocesium through the lake ecosystems were studied during 1986-1990. Levels of Cs-137, Cs-134 and K-40 in water, surface sediment, detritus (sediment traps) and different trophic levels of the food chains of Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) were monitored in a series of lakes forming a matrix of 4 natural lakes and 3 lake reservoirs, with or without the introduced new fish food organism, Mysis relicta. The reservoirs were found to act as sinks for radiocesium with extensive accumulation recorded in water, detritus, sediment, invertebrates and salmonids. Whereas concentrations in water and biota have declined from the extreme peak levels in 1986-1987, the levels in surface sediment increased extensively until fall of 1988. The concentration of Cs-137 in fish populations feeding on benthic invertebrates, i.e. mysids and amphipods, were significantly higher than in planktivorous fish. During the three first winters a significant increase in levels of Cs-137 in winter active Arctic char were recorded, whereas the levels declined during the succeeding summers. The introduced Mysis relicta were found to enhance the transport of Cs-137 from zooplankton and settling particles to Arctic char and brown trout. The results suggest a successive change in transport of radiocesium from water via zooplankton to planktivorous fish during the early summer of 1986 to post-depositional mobilization via benthic organisms to benthic fish in successive years. (213 refs.) (au)

  19. Arctic Submarine Slope Stability

    Science.gov (United States)

    Winkelmann, D.; Geissler, W.

    2010-12-01

    Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are

  20. Vertebrate Fossils Imply Paleo-elevations of the Tibetan Plateau

    Science.gov (United States)

    Deng, T.; Wang, X.; Li, Q.; Wu, F.; Wang, S.; Hou, S.

    2017-12-01

    The uplift of the Tibetan Plateau remains unclear, and its paleo-elevation reconstructions are crucial to interpret the geodynamic evolution and to understand the climatic changes in Asia. Uplift histories of the Tibetan Plateau based on different proxies differ considerably, and two viewpoints are pointedly opposing on the paleo-elevation estimations of the Tibetan Plateau. One viewpoint is that the Tibetan Plateau did not strongly uplift to reach its modern elevation until the Late Miocene, but another one, mainly based on stable isotopes, argues that the Tibetan Plateau formed early during the Indo-Asian collision and reached its modern elevation in the Paleogene or by the Middle Miocene. In 1839, Hugh Falconer firstly reported some rhinocerotid fossils collected from the Zanda Basin in Tibet, China and indicated that the Himalayas have uplifted by more than 2,000 m since several million years ago. In recent years, the vertebrate fossils discovered from the Tibetan Plateau and its surrounding areas implied a high plateau since the late Early Miocene. During the Oligocene, giant rhinos lived in northwestern China to the north of the Tibetan Plateau, while they were also distributed in the Indo-Pakistan subcontinent to the south of this plateau, which indicates that the elevation of the Tibetan Plateau was not too high to prevent exchanges of large mammals; giant rhinos, the rhinocerotid Aprotodon, and chalicotheres still dispersed north and south of "Tibetan Plateau". A tropical-subtropical lowland fish fauna was also present in the central part of this plateau during the Late Oligocene, in which Eoanabas thibetana was inferred to be closely related to extant climbing perches from South Asia and Sub-Saharan Africa. In contrast, during the Middle Miocene, the shovel-tusked elephant Platybelodon was found from many localities north of the Tibetan Plateau, while its trace was absent in the Siwaliks of the subcontinent, which implies that the Tibetan Plateau had

  1. Politics of sustainability in the Arctic - a research agenda

    DEFF Research Database (Denmark)

    Gad, Ulrik Pram; Jakobsen, Uffe; Strandsbjerg, Jeppe

    2017-01-01

    and application from the global ecosphere to a regional environment, and, second, how sustainability is again conceptually transformed when meeting Greenlandic ambitions for postcoloniality. This discussion leads us to outline an agenda for how to study the way in which sustainability works as a political concept.......The concept of sustainability has taken centre stage in Arctic politics. However, there is little agreement on what ‘sustainable’ means. For different actors (governments, indigenous people, NGOs, etc.) the concept implies different sets of opportunities and precautions. Sustainability, therefore......, is much more a fundamental idea to be further elaborated depending on contexts than a definable term with a specific meaning. The paper argues a research agenda that aims to map and analyse the role of sustainability in political and economic strategies in the Arctic. Sustainability has become...

  2. Evaluation of an ensemble of Arctic regional climate models

    DEFF Research Database (Denmark)

    Rinke, A.; Dethloff, K.; Cassano, J. J.

    2006-01-01

    Simulations of eight different regional climate models (RCMs) have been performed for the period September 1997-September 1998, which coincides with the Surface Heat Budget of the Arctic Ocean (SHEBA) project period. Each of the models employed approximately the same domain covering the western......, temperature, cloud cover, and long-/shortwave downward radiation between the individual model simulations are investigated. With this work, we quantify the scatter among the models and therefore the magnitude of disagreement and unreliability of current Arctic RCM simulations. Even with the relatively...... constrained experimental design we notice a considerable scatter among the different RCMs. We found the largest across-model scatter in the 2 m temperature over land, in the surface radiation fluxes, and in the cloud cover which implies a reduced confidence level for these variables....

  3. First Record of Eocene Bony Fishes and Crocodyliforms from Canada’s Western Arctic

    Science.gov (United States)

    Eberle, Jaelyn J.; Gottfried, Michael D.; Hutchison, J. Howard; Brochu, Christopher A.

    2014-01-01

    Background Discovery of Eocene non-marine vertebrates, including crocodylians, turtles, bony fishes, and mammals in Canada’s High Arctic was a critical paleontological contribution of the last century because it indicated that this region of the Arctic had been mild, temperate, and ice-free during the early – middle Eocene (∼53–50 Ma), despite being well above the Arctic Circle. To date, these discoveries have been restricted to Canada’s easternmost Arctic – Ellesmere and Axel Heiberg Islands (Nunavut). Although temporally correlative strata crop out over 1,000 km west, on Canada’s westernmost Arctic Island – Banks Island, Northwest Territories – they have been interpreted as predominantly marine. We document the first Eocene bony fish and crocodyliform fossils from Banks Island. Principal Findings We describe fossils of bony fishes, including lepisosteid (Atractosteus), esocid (pike), and amiid, and a crocodyliform, from lower – middle Eocene strata of the Cyclic Member, Eureka Sound Formation within Aulavik National Park (∼76°N. paleolat.). Palynology suggests the sediments are late early to middle Eocene in age, and likely spanned the Early Eocene Climatic Optimum (EECO). Conclusions/Significance These fossils extend the geographic range of Eocene Arctic lepisosteids, esocids, amiids, and crocodyliforms west by approximately 40° of longitude or ∼1100 km. The low diversity bony fish fauna, at least at the family level, is essentially identical on Ellesmere and Banks Islands, suggesting a pan-High Arctic bony fish fauna of relatively basal groups around the margin of the Eocene Arctic Ocean. From a paleoclimatic perspective, presence of a crocodyliform, gar and amiid fishes on northern Banks provides further evidence that mild, year-round temperatures extended across the Canadian Arctic during early – middle Eocene time. Additionally, the Banks Island crocodyliform is consistent with the phylogenetic hypothesis of a Paleogene divergence

  4. First record of eocene bony fishes and crocodyliforms from Canada's Western Arctic.

    Science.gov (United States)

    Eberle, Jaelyn J; Gottfried, Michael D; Hutchison, J Howard; Brochu, Christopher A

    2014-01-01

    Discovery of Eocene non-marine vertebrates, including crocodylians, turtles, bony fishes, and mammals in Canada's High Arctic was a critical paleontological contribution of the last century because it indicated that this region of the Arctic had been mild, temperate, and ice-free during the early - middle Eocene (∼53-50 Ma), despite being well above the Arctic Circle. To date, these discoveries have been restricted to Canada's easternmost Arctic - Ellesmere and Axel Heiberg Islands (Nunavut). Although temporally correlative strata crop out over 1,000 km west, on Canada's westernmost Arctic Island - Banks Island, Northwest Territories - they have been interpreted as predominantly marine. We document the first Eocene bony fish and crocodyliform fossils from Banks Island. We describe fossils of bony fishes, including lepisosteid (Atractosteus), esocid (pike), and amiid, and a crocodyliform, from lower - middle Eocene strata of the Cyclic Member, Eureka Sound Formation within Aulavik National Park (∼76°N. paleolat.). Palynology suggests the sediments are late early to middle Eocene in age, and likely spanned the Early Eocene Climatic Optimum (EECO). These fossils extend the geographic range of Eocene Arctic lepisosteids, esocids, amiids, and crocodyliforms west by approximately 40° of longitude or ∼1100 km. The low diversity bony fish fauna, at least at the family level, is essentially identical on Ellesmere and Banks Islands, suggesting a pan-High Arctic bony fish fauna of relatively basal groups around the margin of the Eocene Arctic Ocean. From a paleoclimatic perspective, presence of a crocodyliform, gar and amiid fishes on northern Banks provides further evidence that mild, year-round temperatures extended across the Canadian Arctic during early - middle Eocene time. Additionally, the Banks Island crocodyliform is consistent with the phylogenetic hypothesis of a Paleogene divergence time between the two extant alligatorid lineages Alligator

  5. Time-to-contact estimation modulated by implied friction.

    Science.gov (United States)

    Yamada, Yuki; Sasaki, Kyoshiro; Miura, Kayo

    2014-01-01

    The present study demonstrated that friction cues for target motion affect time-to-contact (TTC) estimation. A circular target moved in a linear path with a constant velocity and was gradually occluded by a static rectangle. The target moved with forward and backward spins or without spin. Observers were asked to respond at the time when the moving target appeared to pass the occluder. The results showed that TTC was significantly longer in the backward spin condition than in the forward and without-spin conditions. Moreover, similar results were obtained when a sound was used to imply friction. Our findings indicate that the observer's experiential knowledge of motion coupled with friction intuitively modulated their TTC estimation.

  6. Short-Term Market Risks Implied by Weekly Options

    DEFF Research Database (Denmark)

    Andersen, Torben Gustav; Fusari, Nicola; Todorov, Viktor

    a direct way to study volatility and jump risks. Unlike longer-dated options, they are largely insensitive to the risk of intertemporal shifts in the economic environment. Adopting a novel semi-nonparametric approach, we uncover variation in the negative jump tail risk which is not spanned by market......We study short-term market risks implied by weekly S&P 500 index options. The introduction of weekly options has dramatically shifted the maturity profile of traded options over the last five years, with a substantial proportion now having expiry within one week. Such short-dated options provide......" by the level of market volatility and elude standard asset pricing models....

  7. Implied motion language can influence visual spatial memory.

    Science.gov (United States)

    Vinson, David W; Engelen, Jan; Zwaan, Rolf A; Matlock, Teenie; Dale, Rick

    2017-07-01

    How do language and vision interact? Specifically, what impact can language have on visual processing, especially related to spatial memory? What are typically considered errors in visual processing, such as remembering the location of an object to be farther along its motion trajectory than it actually is, can be explained as perceptual achievements that are driven by our ability to anticipate future events. In two experiments, we tested whether the prior presentation of motion language influences visual spatial memory in ways that afford greater perceptual prediction. Experiment 1 showed that motion language influenced judgments for the spatial memory of an object beyond the known effects of implied motion present in the image itself. Experiment 2 replicated this finding. Our findings support a theory of perception as prediction.

  8. Limits on rare B decays B implies μ+μ-K± and B implies μ+μ- K*

    International Nuclear Information System (INIS)

    Anway-Wiese, C.

    1995-01-01

    We report on a search for flavor-changing neutral current decays of B mesons into γγK * and γγK± using data obtained in the Collider Detector at Fermilab (CDF) 1992 endash 1993 data taking run. To reduce the amount of background in our data we use precise tracking information from the CDF silicon vertex detector to pinpoint the location of the decay vertex of the B candidate, and accept only events which have a large decay time.We compare this data to a B meson signal obtained in a similar fashion, but where the muon pairs originate from ψ decays, and calculate the relative branching ratios. In the absence of any indication of flavor-changing neutral current decays we set an upper limits of BR(B implies μμK ± ) much-gt 3.5x10 -5 , and BR(B implies μμK * )much-gt 5.1x10 -5 at 90% confidence level, which are consistent with Standard Model expectations but leave little room for non-standard physics. copyright 1995 American Institute of Physics

  9. State of the Arctic Environment

    International Nuclear Information System (INIS)

    1990-01-01

    The Arctic environment, covering about 21 million km 2 , is in this connection regarded as the area north of the Arctic Circle. General biological and physical features of the terrestrial and freshwater environments of the Arctic are briefly described, but most effort is put into a description of the marine part which constitutes about two-thirds of the total Arctic environment. General oceanography and morphological characteristics are included; e.g. that the continental shelf surrounding the Arctic deep water basins covers approximately 36% of the surface areas of Arctic waters, but contains only 2% of the total water masses. Blowout accident may release thousands of tons of oil per day and last for months. They occur statistically very seldom, but the magnitude underlines the necessity of an efficient oil spill contingency as well as sound safety and quality assurance procedures. Contingency plans should be coordinated and regularly evaluated through simulated and practical tests of performance. Arctic conditions demand alternative measures compared to those otherwise used for oil spill prevention and clean-up. New concepts or optimization of existing mechanical equipment is necessary. Chemical and thermal methods should be evaluated for efficiency and possible environmental effects. Both due to regular discharges of oil contaminated drilled cuttings and the possibility of a blowout or other spills, drilling operations in biological sensitive areas may be regulated to take place only during the less sensitive parts of the year. 122 refs., 8 figs., 8 tabs

  10. Coupling Geophysical, Geotechnical and Stratigraphic Data to Interpret the Genesis of Mega-Scale-Glacial-Lineations on the Yermak Plateau, Arctic Ocean

    Science.gov (United States)

    O'Regan, M. A.; Jakobsson, M.; Kirchner, N.; Dowdeswell, J. A.; Hogan, K.

    2010-12-01

    The recent collection and analysis of multi-beam bathymetry data has revealed Mega-Scale Glacial Lineations (MSGL) in up to 600 m present water depth on the Yermak Plateau (Dowdeswell et al., 2010; Jakobsson et al., 2010). This evidence for large-scale ice grounding in the region supports previous interpretations from side-scan sonar, high-resolution subbottom and multi-channel seismic data. Detailed integration with regional subbottom data illustrates that the formation of the MSGL occurred in the late Quaternary, around MIS6. This event is distinct from a middle Quaternary ice grounding in the same region, that was first recognized by the transition into heavily overconsolidated sediments at ~20 mbsf at Ocean Drilling Program Site 910. While the middle Quaternary ice grounding left an easily recognizable imprint on the geotechnical properties of the sediments, the imprint from the late Quaternary event is far subtler, and not formerly recognized by analysis of sediments from Site 910. Furthermore, stratigraphic information indicates that neither event was associated with significant erosion, implying that the observed stress state of the sediments arose from ice-loading. Coupled with the orientation of the late Quaternary MSGL, the available evidence argues against an active ice-stream being responsible for their formation, and that they were more likely formed by a very large tabular iceberg traversing the ridge. This lends considerable support to the argument that MSGL-like features are not exclusively associated with fast flowing ice-streams. References Jakobsson, M., et al., An Arctic Ocean iceshelf during MIS 6 constrained by new geophysical and geological data. Quaternary Science Reviews (2010), doi:10.1016/j.quascirev.2010.03.015. Dowdeswell, J. A., et al., High-resolution geophysical observations of the Yermak Plateau and northern Svalbard margin: implications for ice-sheet grounding and deep-keeled icebergs. Quaternary Science Reviews (2010), doi:10

  11. Scientific Drilling in the Arctic Ocean: A challenge for the next decades

    Science.gov (United States)

    Stein, R.; Coakley, B.

    2009-04-01

    Although major progress in Arctic Ocean research has been made during the last decades, the knowledge of its short- and long-term paleoceanographic and paleoclimatic history as well as its plate-tectonic evolution is much behind that from the other world's oceans. That means - despite the importance of the Arctic in the climate system - the data base we have from this area is still very weak, and large parts of the climate history have not been recovered at all in sedimentary sections. This lack of knowledge is mainly caused by the major technological/ logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the successful completion of IODP Expedition 302 ("Arctic Coring Expedition" - ACEX), the first Mission Specific Platform (MSP) expedition within the Integrated Ocean Drilling Program - IODP, a new era in Arctic research has begun. For the first time, a scientific drilling in the permanently ice-covered Arctic Ocean was carried out, penetrating about 430 meters of Quaternary, Neogene, Paleogene and Campanian sediment on the crest of Lomonosov Ridge close to the North Pole. The success of ACEX has certainly opened the door for further scientific drilling in the Arctic Ocean, and will frame the next round of questions to be answered from new drill holes to be taken during the next decades. In order to discuss and plan the future of scientific drilling in the Arctic Ocean, an international workshop was held at the Alfred Wegener Institute (AWI) in Bremerhaven/Germany, (Nov 03-05, 2008; convenors: Bernard Coakley/University of Alaska Fairbanks and Ruediger Stein/AWI Bremerhaven). About 95 scientists from Europe, US, Canada, Russia, Japan, and Korea, and observers from oil companies participated in the workshop. Funding of the workshop was provided by the Consortium for Ocean Leadership (US), the European Science Foundation, the Arctic Ocean Sciences Board, and the

  12. Arctic action against climatic changes

    International Nuclear Information System (INIS)

    Njaastad, Birgit

    2000-01-01

    The articles describes efforts to map the climatic changes in the Arctic regions through the Arctic Climate Impact Assessment Project which is a joint venture between eight Arctic countries: Denmark, Canada, the USA, Russia, Finland, Sweden and Norway. The project deals with the consequences of the changes such as the UV radiation due to diminishing ozone layers. The aims are: Evaluate and integrate existing knowledge in the field and evaluate and predict the consequences particularly on the environment both in the present and the future and produce reliable and useful information in order to aid the decision-making processes

  13. Participatory Methods in Arctic Research

    DEFF Research Database (Denmark)

    Faber, Louise

    2018-01-01

    collection, analysis and conclusions and / or knowledge dissemination. The book aims to collect and share experiences from researchers active in engaging research in the Arctic. The articles reflect on the inclusive methods used in the Arctic research, on the cause and purpose thereof, while the methods......This book is a collection of articles written by researchers at Aalborg University, affiliated with AAU Arctic. The articles are about how the researchers in their respective projects work with stakeholders and citizens in different ways, for example in connection with problem formulation, data...... are exemplified to serve as inspiration for other researchers....

  14. Future scientific drilling in the Arctic Ocean: Key objectives, areas, and strategies

    Science.gov (United States)

    Stein, R.; Coakley, B.; Mikkelsen, N.; O'Regan, M.; Ruppel, C.

    2012-04-01

    In spite of the critical role of the Arctic Ocean in climate evolution, our understanding of the short- and long-term paleoceanographic and paleoclimatic history through late Mesozoic-Cenozoic times, as well as its plate-tectonic evolution, remains behind that from the other world's oceans. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the Arctic Coring Expedition - ACEX (or IODP Expedition 302), the first Mission Specific Platform (MSP) expedition within IODP, a new era in Arctic research began (Backman, Moran, Mayer, McInroy et al., 2006). ACEX proved that, with an intensive ice-management strategy, successful scientific drilling in the permanently ice-covered central Arctic Ocean is possible. ACEX is certainly a milestone in Arctic Ocean research, but - of course - further drilling activities are needed in this poorly studied ocean. Furthermore, despite the success of ACEX fundamental questions related to the long- and short-term climate history of the Arctic Ocean during Mesozoic-Cenozoic times remain unanswered. This is partly due to poor core recovery during ACEX and, especially, because of a major mid-Cenozoic hiatus in this single record. Since ACEX, a series of workshops were held to develop a scientific drilling strategy for investigating the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system: - "Arctic Ocean History: From Speculation to Reality" (Bremerhaven/Germany, November 2008); - "Overcoming barriers to Arctic Ocean scientific drilling: the site survey challenge" (Copenhagen/Denmark, November 2011); - Circum-Arctic shelf/upper continental slope scientific drilling workshop on "Catching Climate Change in Progress" (San Francisco/USA, December 2011); - "Coordinated Scientific Drilling in the Beaufort Sea: Addressing

  15. Squaring the Arctic Circle: connecting Arctic knowledge with societal needs

    Science.gov (United States)

    Wilkinson, J.

    2017-12-01

    Over the coming years the landscape of the Arctic will change substantially- environmentally, politically, and economically. Furthermore, Arctic change has the potential to significantly impact Arctic and non-Arctic countries alike. Thus, our science is in-demand by local communities, politicians, industry leaders and the public. During these times of transition it is essential that the links between science and society be strengthened further. Strong links between science and society is exactly what is needed for the development of better decision-making tools to support sustainable development, enable adaptation to climate change, provide the information necessary for improved management of assets and operations in the Arctic region, and and to inform scientific, economic, environmental and societal policies. By doing so tangible benefits will flow to Arctic societies, as well as for non-Arctic countries that will be significantly affected by climate change. Past experience has shown that the engagement with a broad range of stakeholders is not always an easy process. Consequently, we need to improve collaborative opportunities between scientists, indigenous/local communities, private sector, policy makers, NGOs, and other relevant stakeholders. The development of best practices in this area must build on the collective experiences of successful cross-sectorial programmes. Within this session we present some of the outreach work we have performed within the EU programme ICE-ARC, from community meetings in NW Greenland through to sessions at the United Nations Framework Convention on Climate Change COP Conferences, industry round tables, and an Arctic side event at the World Economic Forum in Davos.

  16. How Rapid Change Affects Deltas in the Arctic Region

    Science.gov (United States)

    Overeem, I.; Bendixen, M.

    2017-12-01

    Deltas form where the river drains into the ocean. Consequently, delta depositional processes are impacted by either changes in the respective river drainage basin or by changes in the regional marine environment. In a warming Arctic region rapid change has occurred over the last few decades in both the terrestrial domain as well as in the marine domain. Important terrestrial controls include 1) change in permafrost possibly destabilizing river banks, 2) strong seasonality of river discharge due to a short melting season, 3) high sediment supply if basins are extensively glaciated, 4) lake outbursts and ice jams favoring river flooding. Whereas in the Arctic marine domain sea ice loss promotes wave and storm surge impact, and increased longshore transport. We here ask which of these factors dominate any morphological change in Arctic deltas. First, we analyze hydrological data to assess change in Arctic-wide river discharge characteristics and timing, and sea ice concentration data to map changes in sea ice regime. Based on this observational analysis we set up a number of scenarios of change. We then model hypothetical small-scale delta formation considering change in these primary controls by setting up a numerical delta model, and combining it dynamically with a permafrost model. We find that for typical Greenlandic deltas changes in river forcing due to ice sheet melt dominate the morphological change, which is corroborated by mapping of delta progradation from aerial photos and satellite imagery. Whereas in other areas, along the North Slope and the Canadian Arctic small deltas are more stable or experienced retreat. Our preliminary coupled model allows us to further disentangle the impact of major forcing factors on delta evolution in high-latitude systems.

  17. Stringent Mitigation Policy Implied By Temperature Impacts on Economic Growth

    Science.gov (United States)

    Moore, F.; Turner, D.

    2014-12-01

    Integrated assessment models (IAMs) compare the costs of greenhouse gas mitigation with damages from climate change in order to evaluate the social welfare implications of climate policy proposals and inform optimal emissions reduction trajectories. However, these models have been criticized for lacking a strong empirical basis for their damage functions, which do little to alter assumptions of sustained GDP growth, even under extreme temperature scenarios. We implement empirical estimates of temperature effects on GDP growth-rates in the Dynamic Integrated Climate and Economy (DICE) model via two pathways, total factor productivity (TFP) growth and capital depreciation. Even under optimistic adaptation assumptions, this damage specification implies that optimal climate policy involves the elimination of emissions in the near future, the stabilization of global temperature change below 2°C, and a social cost of carbon (SCC) an order of magnitude larger than previous estimates. A sensitivity analysis shows that the magnitude of growth effects, the rate of adaptation, and the dynamic interaction between damages from warming and GDP are three critical uncertainties and an important focus for future research.

  18. Collective memory in primate conflict implied by temporal scaling collapse.

    Science.gov (United States)

    Lee, Edward D; Daniels, Bryan C; Krakauer, David C; Flack, Jessica C

    2017-09-01

    In biological systems, prolonged conflict is costly, whereas contained conflict permits strategic innovation and refinement. Causes of variation in conflict size and duration are not well understood. We use a well-studied primate society model system to study how conflicts grow. We find conflict duration is a 'first to fight' growth process that scales superlinearly, with the number of possible pairwise interactions. This is in contrast with a 'first to fail' process that characterizes peaceful durations. Rescaling conflict distributions reveals a universal curve, showing that the typical time scale of correlated interactions exceeds nearly all individual fights. This temporal correlation implies collective memory across pairwise interactions beyond those assumed in standard models of contagion growth or iterated evolutionary games. By accounting for memory, we make quantitative predictions for interventions that mitigate or enhance the spread of conflict. Managing conflict involves balancing the efficient use of limited resources with an intervention strategy that allows for conflict while keeping it contained and controlled. © 2017 The Author(s).

  19. Arctic oil and gas 2007

    Energy Technology Data Exchange (ETDEWEB)

    Huntington, Henry P.

    2007-07-01

    The Arctic Council's assessment of oil and gas activities in the Antic is prepared in response to a request from Ministers of the eight Arctic countries. The Ministers called for engagement of all Arctic Council Working Groups in this process, and requested that the Arctic Monitoring and Assessment programme (AMAP) take responsibility for coordinating the work. This Executive Summary is in three parts. Part A presents the main findings of the assessment and related recommendations. Part B is structured in the same manner as Part A and provides additional information for those interested in examining the basis for the conclusions and recommendations that are presented in Part A. Part C presents information on 'gaps in knowledge' and recommendations aimed at filling these gaps. (AG)

  20. Russia's strategy in the Arctic

    DEFF Research Database (Denmark)

    Staun, Jørgen Meedom

    2017-01-01

    Russia's strategy in the Arctic is dominated by two overriding international relations (IR) discourses – or foreign policy directions. On the one hand, there is an IR-realism/geopolitical discourse that puts security first and often has a clear patriotic character, dealing with ‘exploring......’, ‘winning’ or ‘conquering’ the Arctic and putting power, including military power, behind Russia's national interests in the area. Opposed to this is an IR-liberalism, international law-inspired and modernisation-focused discourse, which puts cooperation first and emphasises ‘respect for international law......’, ‘negotiation’ and ‘cooperation’, and labels the Arctic as a ‘territory of dialogue’, arguing that the Arctic states all benefit the most if they cooperate peacefully. After a short but very visible media stunt in 2007 and subsequent public debate by proponents of the IR realism/geopolitical side, the IR...

  1. Acquatorialities of the Arctic Region

    DEFF Research Database (Denmark)

    Harste, Gorm

    2013-01-01

    In order to describe the Arctic system I propose using a concept functionally equivalent to territoriality, namely aquatoriality. Whether communicating about territoriality or aquatoriality, concepts and delimitations are both contingent to forms of communication systems. I will distinguish between...

  2. SCICEX: Submarine Arctic Science Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

  3. Development of arctic wind technology

    Energy Technology Data Exchange (ETDEWEB)

    Holttinen, H.; Marjaniemi, M.; Antikainen, P. [VTT Energy, Espoo (Finland)

    1998-10-01

    The climatic conditions of Lapland set special technical requirements for wind power production. The most difficult problem regarding wind power production in arctic regions is the build-up of hard and rime ice on structures of the machine

  4. Arctic oil and gas 2007

    Energy Technology Data Exchange (ETDEWEB)

    Huntington, Henry P

    2007-07-01

    The Arctic Council's assessment of oil and gas activities in the Antic is prepared in response to a request from Ministers of the eight Arctic countries. The Ministers called for engagement of all Arctic Council Working Groups in this process, and requested that the Arctic Monitoring and Assessment programme (AMAP) take responsibility for coordinating the work. This Executive Summary is in three parts. Part A presents the main findings of the assessment and related recommendations. Part B is structured in the same manner as Part A and provides additional information for those interested in examining the basis for the conclusions and recommendations that are presented in Part A. Part C presents information on 'gaps in knowledge' and recommendations aimed at filling these gaps. (AG)

  5. Accumulation of PCBs and other POPs in Canada's Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2001-02-01

    High concentrations of polychlorinated biphenyls (PCBs) and other persistent organic pollutants (POPs) have been found in sea-food traditionally eaten by First Nations' people of the Arctic. Since PCBs have never been manufactured in the Arctic these high concentrations cannot be attributed to local sources; they must have been transported from other regions. Due to its cold climate, the Arctic acts a sink for contaminants such as PCBs, originating from around the world and carried by Arctic air masses. Semi-volatile compounds are carried to the Arctic by cycles of evaporation, transport and condensation. Rain, snow, ice and dry deposition capture the airborne contaminants and pollute the surface on which they settle. The contaminants are processed in rivers by sedimentation and resuspension of particles, and lakes, estuaries and deltas act as sinks. The effects of these contaminants is not fully understood, although it is clear that they accumulate in fatty tissues, thus posing special danger to First Nations people who are known to consume fatty sea mammals. Inuit adults from Arctic Quebec and Greenland have PCB concentrations in their blood seven times higher than found in North American adults; 35 times higher than Health Canada's 'level of concern' for women of reproductive age. The cleanup of all PCB and other POP sources is believed to be the only preventative solution, but agreement among countries about how to deal with the existing POPs in the environment to date has proven to be difficult.

  6. Bottom-simulating reflector dynamics at Arctic thermogenic gas provinces: An example from Vestnesa Ridge, offshore west Svalbard

    Science.gov (United States)

    Plaza-Faverola, A.; Vadakkepuliyambatta, S.; Hong, W.-L.; Mienert, J.; Bünz, S.; Chand, S.; Greinert, J.

    2017-06-01

    The Vestnesa Ridge comprises a >100 km long sediment drift located between the western continental slope of Svalbard and the Arctic mid-ocean ridges. It hosts a deep water (>1000 m) gas hydrate and associated seafloor seepage system. Near-seafloor headspace gas compositions and its methane carbon isotopic signature along the ridge indicate a predominance of thermogenic gas sources feeding the system. Prediction of the base of the gas hydrate stability zone for theoretical pressure and temperature conditions and measured gas compositions results in an unusual underestimation of the observed bottom-simulating reflector (BSR) depth. The BSR is up to 60 m deeper than predicted for pure methane and measured gas compositions with >99% methane. Models for measured gas compositions with >4% higher-order hydrocarbons result in a better BSR approximation. However, the BSR remains >20 m deeper than predicted in a region without active seepage. A BSR deeper than predicted is primarily explained by unaccounted spatial variations in the geothermal gradient and by larger amounts of thermogenic gas at the base of the gas hydrate stability zone. Hydrates containing higher-order hydrocarbons form at greater depths and higher temperatures and contribute with larger amounts of carbons than pure methane hydrates. In thermogenic provinces, this may imply a significant upward revision (up to 50% in the case of Vestnesa Ridge) of the amount of carbon in gas hydrates.

  7. Can Canada Avoid Arctic Militarization?

    Science.gov (United States)

    2014-05-20

    global market and the evolution of new fracking technology for the extraction of shale hydrocarbons, the development of the Canadian Arctic might not...resources extraction . In hydrocarbons alone, the United States Geological Survey estimates that there are approximately 90 billion barrels of oil...1,669 trillion cubic feet of natural gas , and 44 billion barrels of natural gas liquids currently undiscovered in the Arctic, with 84 percent lying in

  8. Public Perceptions of Arctic Change

    Science.gov (United States)

    Hamilton, L.

    2014-12-01

    What does the general US public know, or think they know, about Arctic change? Two broad nationwide surveys in 2006 and 2010 addressed this topic in general terms, before and after the International Polar Year (IPY). Since then a series of representative national or statewide surveys have carried this research farther. The new surveys employ specific questions that assess public knowledge of basic Arctic facts, along with perceptions about the possible consequences of future Arctic change. Majorities know that late-summer Arctic sea ice area has declined compared with 30 years ago, although substantial minorities -- lately increasing -- believe instead that it has now recovered to historical levels. Majorities also believe that, if the Arctic warms in the future, this will have major effects on the weather where they live. Their expectation of local impacts from far-away changes suggests a degree of global thinking. On the other hand, most respondents do poorly when asked whether melting Arctic sea ice, melting Greenland/Antarctic land ice, or melting Himalayan glaciers could have more effect on sea level. Only 30% knew or guessed the right answer to this question. Similarly, only 33% answered correctly on a simple geography quiz: whether the North Pole could best be described as ice a few feet or yards thick floating over a deep ocean, ice more than a mile thick over land, or a rocky, mountainous landscape. Close analysis of response patterns suggests that people often construct Arctic "knowledge" on items such as sea ice increase/decrease from their more general ideology or worldview, such as their belief (or doubt) that anthropogenic climate change is real. When ideology or worldviews provide no guidance, as on the North Pole or sealevel questions, the proportion of accurate answers is no better than chance. These results show at least casual public awareness and interest in Arctic change, unfortunately not well grounded in knowledge. Knowledge problems seen on

  9. Interaction webs in arctic ecosystems

    DEFF Research Database (Denmark)

    Schmidt, Niels Martin; Hardwick, Bess; Gilg, Olivier

    2017-01-01

    How species interact modulate their dynamics, their response to environmental change, and ultimately the functioning and stability of entire communities. Work conducted at Zackenberg, Northeast Greenland, has changed our view on how networks of arctic biotic interactions are structured, how they ...... that the combination of long-term, ecosystem-based monitoring, and targeted research projects offers the most fruitful basis for understanding and predicting the future of arctic ecosystems....

  10. Wind power in Arctic regions

    International Nuclear Information System (INIS)

    Lundsager, P.; Ahm, P.; Madsen, B.; Krogsgaard, P.

    1993-07-01

    Arctic or semi-arctic regions are often endowed with wind resources adequate for a viable production of electricity from the wind. Only limited efforts have so far been spent to introduce and to demonstrate the obvious synergy of combining wind power technology with the problems and needs of electricity generation in Arctic regions. Several factors have created a gap preventing the wind power technology carrying its full role in this context, including a certain lack of familiarity with the technology on the part of the end-users, the local utilities and communities, and a lack of commonly agreed techniques to adapt the same technology for Arctic applications on the part of the manufacturers. This report is part of a project that intends to contribute to bridging this gap. The preliminary results of a survey conducted by the project are included in this report, which is a working document for an international seminar held on June 3-4, 1993, at Risoe National Laboratory, Denmark. Following the seminar a final report will be published. It is intended that the final report will serve as a basis for a sustained, international effort to develop the wind power potential of the Arctic and semi-arctic regions. The project is carried out by a project group formed by Risoe, PA Energy and BTM Consult. The project is sponsored by the Danish Energy Agency of the Danish Ministry of Energy through grant no. ENS-51171/93-0008. (au)

  11. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2......, 4 and 5, respectively. It is not the intention of the book to give a broad review of the literature on this very wide topic. The book tries to pick up information which is of engineering importance. An obstacle to the study of sedimentation is the scale effect in model tests. Whenever small...

  12. Denitrification activity and oxygen dynamics in Arctic sea ice

    DEFF Research Database (Denmark)

    Glud, Ronnie Nøhr; Stahl, Henrik J.; Rysgaard, Søren

    2008-01-01

    denitrification activity (5-194 mu mol N m(-2) day(-1)) and anammox activity (3-5 mu mol N m(-2) day(-1)) in melt water from both first-year and multi-year sea ice was found. These values correspond to 27 and 7%, respectively, of the benthic denitrification and anammox activities in Arctic sediments. Although we...... a mosaic of microsites of high and low O-2 concentrations. Brine enclosures and channels were strongly O-2 depleted in actively melting sea ice, and anoxic conditions in parts of the brine system would favour anaerobic processes....

  13. The Triassic upwelling system of Arctic Alaska

    Science.gov (United States)

    Yurchenko, I.; Graham, S. A.

    2017-12-01

    The Middle to Upper Triassic Shublik Formation of Arctic Alaska is a laterally and vertically heterogeneous rock unit that has been analyzed both in outcrop and in the subsurface. The Shublik Formation sediments are distinguished by a characteristic set of lithologies that include glauconitic, phosphatic, organic-rich, and cherty facies consistent with a coastal upwelling zone deposition interpretation. It is often recognized by abundance of impressions and shells of distinctive Triassic bivalves. To understand main controls on lithofacies distributions, this study reviews and refines lithologic and paleoenvironmental interpretations of the Shublik Formation, and incorporates the newly acquired detailed geochemical analyses of two complete Shublik cores. This work focuses on organic geochemistry (analyses of biomarkers and diamondoids), chemostratigraphy (hand-held XRF), and iron speciation analysis to reconstruct paleoproductivity and redox conditions. Based on the available evidence, during Shublik deposition, an upwelling-influenced open shelf resulted in high nutrient supply that stimulated algal blooms leading to high net organic productivity, reduced water transparency, oxygen deficiency, and water column stratification. Evidence of such eutrophic conditions is indicated by the lack of photic benthic organisms, bioturbation and trace fossils, and dominance of the monospecific light-independent epibenthic bivalves. The flat, subcircular, thin shells of these carbonate-secreting organisms allowed them to adapt to dysoxic conditions, and float on soft, soupy, muddy substrate. The distinctive clay- and organic-rich facies with abundant bivalves occurred on the mid to outer stable broad shelf, and were deposited when organic productivity at times overlapped with periods of increased siliciclastic input controlled by sea level and changes in local sediment dispersal systems, and therefore are more spatially and temporally localized than the widespread clay

  14. Sensitivity of the Arctic Ocean gas hydrate to climate changes in the period of 1948-2015

    Science.gov (United States)

    Malakhova, Valentina V.; Golubeva, Elena N.; Iakshina, Dina F.

    2017-11-01

    The objective of the present study is to analyze the interactions between a methane hydrates stability zone and the ocean temperature variations and to define the hydrate sensitivity to the contemporary warming in the Arctic Ocean. To obtain the spatial-temporary variability of the ocean bottom temperature we employ the ICMMG regional Arctic-North Atlantic ocean model that has been developed in the Institute of Computational Mathematics and Mathematical Geophysics. With the ice-ocean model the Arctic bottom water temperatures were analyzed. The resulting warming ocean bottom water is spatially inhomogeneous, with a strong impact by the Atlantic inflow on shallow regions of 200-500 m depth. Results of the mathematical modeling of the dynamics of methane hydrate stability zone in the Arctic Ocean sediment are reported. We find that the reduction of the methane hydrate stability zone occurs in the Arctic Ocean between 250 and 400 m water depths within the upper 100 m of sediment in the area influenced by the Atlantic inflow. We have identified the areas of the Arctic Ocean where an increase in methane release is probable to occur at the present time.

  15. Analysis of Federal Subsidies: Implied Price of Carbon

    Energy Technology Data Exchange (ETDEWEB)

    D. Craig Cooper; Thomas Foulke

    2010-10-01

    For informed climate change policy, it is important for decision makers to be able to assess how the costs and benefits of federal energy subsidies are distributed and to be able to have some measure to compare them. One way to do this is to evaluate the implied price of carbon (IPC) for a federal subsidy, or set of subsidies; where the IPC is the cost of the subsidy to the U.S. Treasury divided by the emissions reductions it generated. Subsidies with lower IPC are more cost effective at reducing greenhouse gas emissions, while subsidies with a negative IPC act to increase emissions. While simple in concept, the IPC is difficult to calculate in practice. Calculation of the IPC requires knowledge of (i) the amount of energy associated with the subsidy, (ii) the amount and type of energy that would have been produced in the absence of the subsidy, and (iii) the greenhouse gas emissions associated with both the subsidized energy and the potential replacement energy. These pieces of information are not consistently available for federal subsidies, and there is considerable uncertainty in cases where the information is available. Thus, exact values for the IPC based upon fully consistent standards cannot be calculated with available data. However, it is possible to estimate a range of potential values sufficient for initial comparisons. This study has employed a range of methods to generate “first order” estimates for the IPC of a range of federal subsidies using static methods that do not account for the dynamics of supply and demand. The study demonstrates that, while the IPC value depends upon how the inquiry is framed and the IPC cannot be calculated in a “one size fits all” manner, IPC calculations can provide a valuable perspective for climate policy analysis. IPC values are most useful when calculated within the perspective of a case study, with the method and parameters of the calculation determined by the case. The IPC of different policy measures can

  16. Variability of the Arctic Basin Oceanographic Fields

    National Research Council Canada - National Science Library

    Sabinin, K

    1996-01-01

    ...." Special attention was paid to Atlantic Water in the Arctic Ocean which seems to be the main source of information in acoustic monitoring of the ocean, in the framework of the Arctic-ATOC program...

  17. Meteorological conditions in the central Arctic summer during the Arctic Summer Cloud Ocean Study (ASCOS

    Directory of Open Access Journals (Sweden)

    M. Tjernström

    2012-08-01

    Full Text Available Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as the Arctic Summer Cloud-Ocean Study (ASCOS, described here. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this.

    To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean: the AOE-96, SHEBA and AOE-2001 expeditions.

    We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of surface-shear and

  18. Sources, degradation and transport of terrigenous organic carbon on the East Siberian Arctic Shelf Seas

    Science.gov (United States)

    Tesi, Tommaso; Semiletov, Igor; Dudarev, Oleg; Gustafsson, Örjan

    2013-04-01

    Recent studies suggest that the present hydrological regime increase observed in the Arctic rivers is mainly the consequence of the changes in permafrost conditions as a result of climate warming. Given the enormous amount of carbon stored in coastal and terrestrial permafrost the potentially increased supply from this large carbon pool to the coastal Arctic Ocean, possibly associated with a translocated release to the atmosphere as CO2, is considered a plausible scenario in a warming climate. However, there is not sufficient information regarding the reactivity of terrigenous material once supplied to the Arctic Ocean. In this study, we address this critical issue by examining the organic composition of surface sediments collected over extensive scales on the East Siberian Arctic Shelf (ESAS) as part of the International Siberian Shelf Study (ISSS). The ESAS represents by far the largest shelf of the Arctic Ocean. Samples were collected from the inner- to the outer-shelf following the sediment transport pathway in a region between the Lena and the Kolyma rivers. The analytical approach includes the characterization of marine and land-derived carbon using a large number of molecular biomarkers obtained by alkaline CuO oxidation such as lignin-phenols, cutin-derived products, p-hydroxy benzenes, benzoic acids, fatty acids, and dicarboxylic acids. Our results indicated high concentrations of terrigenous material in shallow sediments and a marked decrease of terrestrial biomarkers with increasing distance from the coastline. In parallel, lignin-based degradation proxies suggested highly altered terrigenous carbon in mid- and outer-shelf sediments compared to coastal sediments. Furthermore, the ratio of cutin-derived products over lignin significantly increased along the sediment transport pathway. Considering that cutin is considered to be intrinsically more reactive compared to lignin, high values of this ratio off the coastal region were interpreted as selective

  19. Special Issue ;Sediment cascades in cold climate geosystems;

    Science.gov (United States)

    Morche, David; Krautblatter, Michael; Beylich, Achim A.

    2017-06-01

    This Editorial introduces the Special Issue on sediment cascades in cold climate geosystems that evolved from the eighth I.A.G./A.I.G. SEDIBUD (Sediment Budgets in Cold Environments; http://www.geomorph.org/sedibud-working-group/) workshop. The workshop was held from 1st to 4th September 2014 at the Environmental Research Station ;Schneefernerhaus; (http://www.schneefernerhaus.de/en/home.html) located at Mt. Zugspitze, the highest peak of Germany, (2962 m asl). Paper and poster presentations focused on observations, measurements and modeling of geomorphological processes in sediment cascades in cold climate geosystems. This resulting Special Issue brings together ten selected contributions from arctic and alpine environments.

  20. Large-scale subduction of continental crust implied by India-Asia mass-balance calculation

    Science.gov (United States)

    Ingalls, Miquela; Rowley, David B.; Currie, Brian; Colman, Albert S.

    2016-11-01

    Continental crust is buoyant compared with its oceanic counterpart and resists subduction into the mantle. When two continents collide, the mass balance for the continental crust is therefore assumed to be maintained. Here we use estimates of pre-collisional crustal thickness and convergence history derived from plate kinematic models to calculate the crustal mass balance in the India-Asia collisional system. Using the current best estimates for the timing of the diachronous onset of collision between India and Eurasia, we find that about 50% of the pre-collisional continental crustal mass cannot be accounted for in the crustal reservoir preserved at Earth's surface today--represented by the mass preserved in the thickened crust that makes up the Himalaya, Tibet and much of adjacent Asia, as well as southeast Asian tectonic escape and exported eroded sediments. This implies large-scale subduction of continental crust during the collision, with a mass equivalent to about 15% of the total oceanic crustal subduction flux since 56 million years ago. We suggest that similar contamination of the mantle by direct input of radiogenic continental crustal materials during past continent-continent collisions is reflected in some ocean crust and ocean island basalt geochemistry. The subduction of continental crust may therefore contribute significantly to the evolution of mantle geochemistry.

  1. Redefining U.S. Arctic Strategy

    Science.gov (United States)

    2015-05-15

    responsibility shifts 21 Barno, David and Nora Bensahel. The Anti-Access Challenge you’re not thinking...International Affairs 85, no. 6 (2009). 38 Barno, David and Nora Bensahel. THE ANTI-ACCESS CHALLENGE YOU’RE NOT THINKING ABOUT, 05 May 2015...and Rescue in the Arctic, 22 June 2011. Arctic Council Secretariat. About the Arctic Council, Arctic Council, 2011. Barno, David and Nora

  2. Scaling Laws in Arctic Permafrost River Basins: Statistical Signature in Transition

    Science.gov (United States)

    Rowland, J. C.; Gangodagamage, C.; Wilson, C. J.; Prancevic, J. P.; Brumby, S. P.; Marsh, P.; Crosby, B. T.

    2011-12-01

    from the pattern in temperate landscapes. Our results suggest that Arctic landscapes are characterized by relatively undissected, long planar hillslopes, which convey sediment to quasi-fluvial valleys through long (~ 1 km) flow-paths. Further, we also document that broad planar hillslopes abruptly converge, forcing rapid subsurface flow accumulation at channel heads. This topographic characteristic can successfully be used to explain the position of erosion features. Finally we estimate the landscape model parameters for the arctic landscape that can be successfully used to model development and validation purposes.

  3. Long-range transport of persistent pollutants into Arctic regions; Schadstoff-Ferntransport in die Arktis

    Energy Technology Data Exchange (ETDEWEB)

    Kallenborn, R.; Herzke, D. [Norwegian Inst. for Air Research, The Polar Environmental Centre, Tromso (Norway)

    2001-07-01

    In recent years, high concentrations of persistent pollutants (organic chemicals, metals) were detected in top predators of the Arctic food chain and indigenous peoples from the Canadian and Greenland Arctic, although no local contamination sources are known. The comprehensive, scientific investigations of the past 20 years confirmed that the combination of atmospheric and waterborne long-range transport is the major source of the high concentrations of persistent organic pollutants (POPs) in the pristine Arctic environment. However, also pelagic marine organisms (e.g. Atlantic cod, marine mammals) can transport large amounts of persistent pollutants in their lipids and introduce contaminants into the Arctic food web. Thus, the pollutants are transported into the Arctic and subsequently accumulated through the short and unbranched Arctic food web of the top predators. The most accepted theory nowadays describes the long-range transport of persistent pollutants as a combination of atmospheric and sea current transport, or as a 'global distillation' process. Depending on such physical properties of the substances as vapour pressure and the ambient temperature, persistent (semivolatile) contaminants are transported over different distances prior to deposition (sea surface, sediment, soil). After the deposition, however, and depending on the weather conditions and surrounding temperature, persistent pollutants will be re-evaporated into the atmosphere and undergo further atmospheric transport to the Arctic region. This process is also called the 'grasshopper effect'. The global transport of persistent pollutants into Arctic regions can be described as a repeatedly occurring combination of atmospheric and waterborne transport in which the main transport vehicle depends on the physical properties of the transported compound. The role of characteristic meteorological conditions in the respective climate zones through which the contaminant is

  4. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    Science.gov (United States)

    Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

    2016-01-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial.

  5. Increased Surface Wind Speeds Follow Diminishing Arctic Sea Ice

    Science.gov (United States)

    Mioduszewski, J.; Vavrus, S. J.; Wang, M.; Holland, M. M.; Landrum, L.

    2017-12-01

    Projections of Arctic sea ice through the end of the 21st century indicate the likelihood of a strong reduction in ice area and thickness in all seasons, leading to a substantial thermodynamic influence on the overlying atmosphere. This is likely to have an effect on winds over the Arctic Basin, due to changes in atmospheric stability and/or baroclinicity. Prior research on future Arctic wind changes is limited and has focused mainly on the practical impacts on wave heights in certain seasons. Here we attempt to identify patterns and likely mechanisms responsible for surface wind changes in all seasons across the Arctic, particularly those associated with sea ice loss in the marginal ice zone. Sea level pressure, near-surface (10 m) and upper-air (850 hPa) wind speeds, and lower-level dynamic and thermodynamic variables from the Community Earth System Model Large Ensemble Project (CESM-LE) were analyzed for the periods 1971-2000 and 2071-2100 to facilitate comparison between a present-day and future climate. Mean near-surface wind speeds over the Arctic Ocean are projected to increase by late century in all seasons but especially during autumn and winter, when they strengthen by up to 50% locally. The most extreme wind speeds in the 90th percentile change even more, increasing in frequency by over 100%. The strengthened winds are closely linked to decreasing lower-tropospheric stability resulting from the loss of sea ice cover and consequent surface warming (locally over 20 ºC warmer in autumn and winter). A muted pattern of these future changes is simulated in CESM-LE historical runs from 1920-2005. The enhanced winds near the surface are mostly collocated with weaker winds above the boundary layer during autumn and winter, implying more vigorous vertical mixing and a drawdown of high-momentum air.The implications of stronger future winds include increased coastal hazards and the potential for a positive feedback with sea ice by generating higher winds and

  6. Mercury in dated Greenland marine sediments

    DEFF Research Database (Denmark)

    Asmund, G.; Nielsen, S.P.

    2000-01-01

    Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age of the sedi......Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age...... indicating that the mercury mainly originates from atmospheric washout. But the large variability indicates that other processes also influence the mercury flux to Arctic marine sediments. (C) 2000 Elsevier Science B.V. All rights reserved....

  7. Calibration and application of the IP25 biomarker for Arctic sea ice reconstructions

    Science.gov (United States)

    Cabedo Sanz, P.; Navarro Rodriguez, A.; Belt, S. T.; Brown, T. A.; Knies, J.; Husum, K.; Giraudeau, J.; Andrews, J.

    2012-04-01

    The presence of the sea ice diatom biomarker IP25 in Arctic marine sediments has been used in previous studies as a proxy for past spring sea ice occurrence and as an indicator of wider palaeoenvironmental conditions for different regions of the Arctic over various timescales [e.g. 1, 3]. In addition, measurement of IP25 has also been applied as a sea ice origin tracer for studying the transfer of organic carbon through Arctic food-webs [2]. The current study focuses on three main areas: (1) In order to improve on the quantitative analytical aspects of IP25 based research, we present here the results of a large scale extraction, purification and identification procedure for IP25 from marine sediments. This has confirmed the structure of IP25 in sediments and enabled more robust quantitative measurements by gas chromatography - mass spectrometry (GC-MS) to be established. (2) Quantitative measurements of IP25 from a sediment core from Andfjord (continental shelf, Tromsø, Norway) have been determined for the period 6.3 to 14.3 ka BP. The results of this study add significant further information to that reported previously from other biomarker studies for this core (e.g. brassicasterol) [4]. (3) Analytical detection issues (GC-MS) regarding the occurrence of IP25 in other sub-Arctic regions (e.g. East Greenland - North Iceland area) will be presented and discussed with relation to other proxy data (e.g. IRD). Belt, S. T., Vare, L. L., Massé, G., Manners, H. R., Price, J. C., MacLachlan, S. E., Andrews, J. T. & Schmidt, S. (2010) 'Striking similarities in temporal changes to spring sea ice occurrence across the central Canadian Arctic Archipelago over the last 7000 years', Quaternary Science Reviews, 29 (25-26), pp. 3489-3504. Brown, T. A. & Belt, S. T. (2012) 'Identification of the sea ice diatom biomarker IP25 in Arctic benthic macrofauna: direct evidence for a sea ice diatom diet in Arctic heterotrophs', Polar Biology, 35, pp. 131-137. Müller, J., Massé, G

  8. NATIONAL ATLAS OF THE ARCTIC

    Directory of Open Access Journals (Sweden)

    Nikolay S. Kasimov

    2018-01-01

    Full Text Available The National Atlas of the Arctic is a set of spatio-temporal information about the geographic, ecological, economic, historical-ethnographic, cultural, and social features of theArcticcompiled as a cartographic model of the territory. The Atlas is intended for use in a wide range of scientific, management, economic, defense, educational, and public activities. The state policy of theRussian Federationin the Arctic for the period until 2020 and beyond, states that the Arctic is of strategic importance forRussiain the 21st century. A detailed description of all sections of the Atlas is given. The Atlas can be used as an information-reference and educational resource or as a gift edition.

  9. Arctic Basemaps In Google Maps

    DEFF Research Database (Denmark)

    Muggah, J.; Mioc, Darka

    2010-01-01

    The Ocean Mapping Group has been collecting data in the Arctic since 2003 and there are approximately 2,000 basemaps. In the current online storage format used by the OMG, it is difficult to view the data and users cannot easily pan and zoom. The purpose of this research is to investigate...... the advantages of the use of Google Maps, to display the OMG's Arctic data. The map should should load the large Artic dataset in a reasonable time. The bathymetric images were created using software in Linux written by the OMG, and a step-by-step process was used to create images from the multibeam data...... collected by the OMG in the Arctic. The website was also created using Linux operating system. The projection needed to be changed from Lambert Conformal Conic (useful at higher Latitudes) to Mercator (used by Google Maps) and the data needed to have a common colour scheme. After creating and testing...

  10. Interaction webs in arctic ecosystems

    DEFF Research Database (Denmark)

    Schmidt, Niels M.; Hardwick, Bess; Gilg, Olivier

    2017-01-01

    How species interact modulate their dynamics, their response to environmental change, and ultimately the functioning and stability of entire communities. Work conducted at Zackenberg, Northeast Greenland, has changed our view on how networks of arctic biotic interactions are structured, how...... they vary in time, and how they are changing with current environmental change: firstly, the high arctic interaction webs are much more complex than previously envisaged, and with a structure mainly dictated by its arthropod component. Secondly, the dynamics of species within these webs reflect changes...... that the combination of long-term, ecosystem-based monitoring, and targeted research projects offers the most fruitful basis for understanding and predicting the future of arctic ecosystems....

  11. Environmental radioactivity in the Arctic

    International Nuclear Information System (INIS)

    Strand, P.; Cooke, A.

    1995-01-01

    The conference considered several broad themes: (1) assessment of releases from landbased sources and river transport, (2) assessment of dumping of nuclear waste, (3) arctic radioecology, (4) assessment of impacts of nuclear explosions and accidents, (5) nuclear safety and consequences of nuclear accidents in the arctic, and (6) waste management. The presentations demonstrated that current levels of radioactivity in the Arctic are generally low. The two most important sources are global fallout from the nuclear weapons tests of the 1950's and 1960's, and discharges to the sea from reprocessing plants in Western Europe which are transported northward by prevailing currents. The conference was attended by scientists from 17 countries and served as a forum for collection and dissemination of information on the range of themes and described above. It is hoped that this will serve to increase awareness of areas of uncertainty and act as a stimulus to further research

  12. The Arctic tourism in Russia

    Directory of Open Access Journals (Sweden)

    Yury F. Lukin

    2016-12-01

    Full Text Available In the new book "Arctic tourism in Russia" the basic concepts, resource potential, attractiveness (from Lat. Attrahere: to attract, opportunities and threats of environmental, cruise, international, and other types of tourism in the Arctic are system-based analyzed, for the first time in the literature. The sphere of tourism has becoming an integral sector of the economy, having a multiplicative effect for the development of infrastructure, social services, employment. Reference materials about the tourism products in the Russian Arctic and Far North regions are published, including the Arkhangelsk and Murmansk regions; Republic of Karelia, Komi, Sakha (Yakutia; Nenets, the Yamalo-Nenets, Khanty-Mansiysk, the Chukotka Autonomous Districts; Taimyr Dolgan-Nenets Municipal District, Turukhansk district, the city of Norilsk of the Krasnoyarsk region; Magadan region, Kamchatka region.

  13. Sea surface salinity of the Eocene Arctic Azolla event using innovative isotope modeling

    Science.gov (United States)

    Speelman, E. N.; Sewall, J. O.; Noone, D.; Huber, M.; Sinninghe Damste, J. S.; Reichart, G. J.

    2009-04-01

    With the realization that the Eocene Arctic Ocean was covered with enormous quantities of the free floating freshwater fern Azolla, new questions regarding Eocene conditions facilitating these blooms arose. Our present research focuses on constraining the actual salinity of, and water sources for, the Eocene Arctic basin through the application of stable water isotope tracers. Precipitation pathways potentially strongly affect the final isotopic composition of water entering the Arctic Basin. Therefore we use the Community Atmosphere Model (CAM3), developed by NCAR, combined with a recently developed integrated isotope tracer code to reconstruct the isotopic composition of global Eocene precipitation and run-off patterns. We further addressed the sensitivity of the modeled hydrological cycle to changes in boundary conditions, such as pCO2, sea surface temperatures (SSTs) and sea ice formation. In this way it is possible to assess the effect of uncertainties in proxy estimates of these parameters. Overall, results of all runs with Eocene boundary conditions, including Eocene topography, bathymetry, vegetation patterns, TEX86 derived SSTs and pCO2 estimates, show the presence of an intensified hydrological cycle with precipitation exceeding evaporation in the Arctic region. Enriched, precipitation weighted, isotopic values of around -120‰ are reported for the Arctic region. Combining new results obtained from compound specific isotope analyses (δD) on terrestrially derived n-alkanes extracted from Eocene sediments, and model outcomes make it possible to verify climate reconstructions for the middle Eocene Arctic. Furthermore, recently, characteristic long-chain mid-chain ω20 hydroxy wax constituents of Azolla were found in ACEX sediments. δD values of these C32 - C36 diols provide insight into the isotopic composition of the Eocene Arctic surface water. As the isotopic signature of the runoff entering the Arctic is modelled, and the final isotopic composition of

  14. Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years

    DEFF Research Database (Denmark)

    Rezende, Julia Rosa de; Kjeldsen, Kasper Urup; Hubert, Casey RJ

    2013-01-01

    S rRNA and of the dissimilatory (bi)sulfite reductase (dsrAB) genes within the endospore-forming SRB genus Desulfotomaculum. The thermophilic Desulfotomaculum community in Aarhus Bay sediments consisted of at least 23 species-level 16S rRNA sequence phylotypes. In two cases, pairs of identical 16S r......RNA and dsrAB sequences in Arctic surface sediment 3000km away showed that the same phylotypes are present in both locations. Radiotracer-enhanced most probable number analysis revealed that the abundance of endospores of thermophilic SRB in Aarhus Bay sediment was ca. 104 per cm3 at the surface and decreased...... in water masses preceding sedimentation. The sources of these thermophiles remain enigmatic, but at least one source may be common to both Aarhus Bay and Arctic sediments....

  15. Abundant Pre-Industrial Carbon Emitted by Arctic Inland Waters

    Science.gov (United States)

    Dean, J.; Van der Velde, Y.; Billett, M. F.; Dinsmore, K. J.; Garnett, M.; Meisel, O.; Dolman, A. J.

    2017-12-01

    Mobilization of carbon (C) derived from soil/sediment organic matter into inland freshwaters constitutes a substantial, but poorly-constrained, component of the global C cycle. Radiocarbon (14C) analysis has proven a valuable tool in tracing the sources and fate of mobilized C, but aquatic 14C studies in permafrost regions rarely detect 'old' C (assimilated from the atmosphere into plants and soil prior to AD1950). This is partly due to a focus on dissolved organic C (DOC) in many Arctic inland water 14C studies to date, now known to be an insensitive method for detecting old C. Crucially, the emission of greenhouse gases (GHGs) derived from old permafrost C by aquatic systems contributes to a positive climate feedback loop: the 'Permafrost Climate Feedback' (PCF). Here, we measure directly the 14C content and quantify fluxes of aquatic CO2 and CH4, alongside DOC and particulate-OC, in freshwater systems of the Canadian and Siberian Arctic tundra - the first such concurrent 14C measurements from freshwater systems. Aquatic C increased in age significantly over the snow-free season as the active layer deepened (Figure 1). However, 'modern' C (assimilated since AD1950) still dominated aquatic CO2 and CH4 emissions, except where deep ancient (6,000 to 50,000 yBP) C was exposed. Age distribution modeling of these bulk 14C samples indicated that 'pre-industrial' C (assimilated prior to AD1750) comprised 15-30% of aquatic GHGs (Figure 1). Further, we estimate that 15-20% of total CO2 and CH4 emissions were derived from old C previously locked up in permafrost soils and thus contributed to the PCF. These results demonstrate the previously unknown presence of aged C within Arctic headwater GHG emissions that could be equivalent to 7.5-28.2 Tg C yr-1 across the pan-Arctic.

  16. The Arctic : the great breakup

    International Nuclear Information System (INIS)

    Lemieux, R.

    2007-01-01

    The impact that climate change has had on the famous Northwest passage in Canada's Arctic was discussed. The water channel through the Arctic Islands is now navigable during the summer and it has been predicted that in 40 years, it may be navigable throughout the entire year. Although the Arctic is still covered with snow, the icebergs which navigators have feared no longer exist. Environment Canada has cautioned that Canada's extreme north would be most at risk from global warming, with temperatures increasing by 6 degrees, or 3 times higher than in moderate zones. The joint Canadian-United States program Surface Heat Budget of the Arctic has also confirmed that the waters of the Beaufort Sea are less salty and relatively warmer. Climatologists also project that the predicted increase in snowfall will act as an insulation blanket, thereby preventing the ice from thickening. Scientists stated that the gigantic polar cap, which has been frozen for the past 3.2 million years, will have fissures everywhere by 2080. The Northwest passage will become easily accessible in less than 10 years. This article raised questions regarding the role of the Northwest passage as an international maritime route. It presented the case of the first successful passage of a U.S. commercial oil tanker in 1969 which created controversy regarding Canada's territorial waters. Fourty years later, this issue is still not resolved. The article questioned whether there should be more cooperation on both the Canadian and American sides in light of the shared common interests such as commerce, science and security. It was noted that although Canada has sovereignty of the Arctic Islands, there are eight other countries who share the Arctic. 4 figs

  17. The Arctic policy of China and Japan

    DEFF Research Database (Denmark)

    Tonami, Aki

    2014-01-01

    At the May 2013 Arctic Council Ministerial Meeting, five Asian states, namely China, Japan, India, Singapore and South Korea, were accepted to become new Permanent Observers at the Arctic Council. Nonetheless, little attention has been paid to the Asian states and their interest in the Arctic. Most...... discussions have focused on China and the assessment of China’s interest in the Arctic is divided. This paper attempts to fill this gap by presenting and comparing the various components of the Arctic policies of China and Japan. Referring to Putnam’s model of the “two-level game” and Young’s categorization...

  18. Anthropogenic radioactivity in the Arctic Ocean. Review of the results from the joint German project

    International Nuclear Information System (INIS)

    Nies, H.; Harms, I.H.; Karcher, M.J.; Dethleff, D.; Bahe, C.

    1999-01-01

    The paper presents the results of the joint project carried out in Germany in order to assess the consequences in the marine environment from the dumping of nuclear wastes in the Kara and Barents Seas. The project consisted of experimental work on measurements of radionuclides in samples from the Arctic marine environment and numerical modelling of the potential pathways and dispersion of contaminants in the Arctic Ocean. Water and sediment samples were collected for determination of radionuclide such as 137Cs, 90Sr, 239+240Pu, 238Pu, and 241Am and various organic micropollutants. In addition, a few water and numerous surface sediment samples collected in the Kara Sea and from the Kola peninsula were taken by Russian colleagues and analysed for artificial radionuclides by the BSH laboratory. The role of transport by sea ice from the Kara Sea into the Arctic Ocean was assessed by a small subgroup at GEOMAR. This transport process might be considered as a rapid contribution due to entrainment of contaminated sediments into sea ice, following export from the Kara Sea into the transpolar ice drift and subsequent release in the Atlantic Ocean in the area of the East Greenland Current. Numerical modelling of dispersion of pollutants from the Kara and Barents Seas was carried out both on a local scale for the Barents and Kara Seas and for long range dispersion into the Arctic and Atlantic Oceans. Three-dimensional baroclinic circulation models were applied to trace the transport of pollutants. Experimental results were used to validate the model results such as the discharges from the nuclear reprocessing plant at Sellafield and subsequent contamination of the North Sea up the Arctic Seas

  19. Anthropogenic radioactivity in the Arctic Ocean--review of the results from the joint German project.

    Science.gov (United States)

    Nies, H; Harms, I H; Karcher, M J; Dethleff, D; Bahe, C

    1999-09-30

    The paper presents the results of the joint project carried out in Germany in order to assess the consequences in the marine environment from the dumping of nuclear wastes in the Kara and Barents Seas. The project consisted of experimental work on measurements of radionuclides in samples from the Arctic marine environment and numerical modelling of the potential pathways and dispersion of contaminants in the Arctic Ocean. Water and sediment samples were collected for determination of radionuclide such as 137Cs, 90Sr, 239 + 240Pu, 238Pu, and 241Am and various organic micropollutants. In addition, a few water and numerous surface sediment samples collected in the Kara Sea and from the Kola peninsula were taken by Russian colleagues and analysed for artificial radionuclide by the BSH laboratory. The role of transport by sea ice from the Kara Sea into the Arctic Ocean was assessed by a small subgroup at GEOMAR. This transport process might be considered as a rapid contribution due to entrainment of contaminated sediments into sea ice, following export from the Kara Sea into the transpolar ice drift and subsequent release in the Atlantic Ocean in the area of the East Greenland Current. Numerical modelling of dispersion of pollutants from the Kara and Barents Seas was carried out both on a local scale for the Barents and Kara Seas and for long range dispersion into the Arctic and Atlantic Oceans. Three-dimensional baroclinic circulation models were applied to trace the transport of pollutants. Experimental results were used to validate the model results such as the discharges from the nuclear reprocessing plant at Sellafield and subsequent contamination of the North Sea up the Arctic Seas.

  20. Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean: an integrative analysis of spatial variability and biophysical forcings

    Directory of Open Access Journals (Sweden)

    A. Forest

    2013-05-01

    Full Text Available A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here we combine mooring times series, ship-based measurements and remote sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their determinants in summer. Flux data were obtained with sediment traps moored around 125 m and via a regional empirical algorithm applied to particle size distributions (17 classes from 0.08–4.2 mm measured by an Underwater Vision Profiler 5. The low fractal dimension (i.e., porous, fluffy particles derived from the algorithm (1.26 ± 0.34 and the dominance (~ 77% of rapidly sinking small aggregates (p r2 cum. = 0.37. Bacteria were correlated with small aggregates, while northeasterly wind was associated with large size classes (> 1 mm ESD, but these two factors were weakly related with each other. Copepod biomass was overall negatively correlated (p < 0.05 with vertical POC fluxes, implying that metazoans acted as regulators of export fluxes, even if their role was minor given that our study spanned the onset of diapause. Our results demonstrate that on interior Arctic shelves where productivity is low in mid-summer, localized upwelling zones (nutrient enrichment may result in the formation of large filamentous phytoaggregates that are not substantially retained by copepod and bacterial communities.

  1. A comparison of PCB bioaccumulation factors between an arctic and a temperate marine food web.

    Science.gov (United States)

    Sobek, Anna; McLachlan, Michael S; Borgå, Katrine; Asplund, Lillemor; Lundstedt-Enkel, Katrin; Polder, Anuschka; Gustafsson, Orjan

    2010-06-01

    To test how environmental conditions in the Arctic and the resulting ecological adaptations affect accumulation of persistent organic pollutants (POPs) in the marine food web, bioaccumulation of four polychlorinated biphenyls (PCBs) in an arctic (Barents Sea 77 degrees N-82 degrees N) and a temperate marine (Baltic Sea 54 degrees N-62 degrees N) food web were compared. Three different trophic levels were studied (zooplankton, fish, and seal), representing the span from first-level consumer to top predator. Previously published high-quality data on PCB water concentrations in the two areas were used for calculation of bioaccumulation factors (BAF). BAF was calculated as the ratio of the PCB concentration in the organism ([PCB](org); pg/kg lipid) to the dissolved water concentration (C(w); pg/L). The BAF(Arctic):BAF(Temperate) ratios were above 1 for all four PCB congeners in zooplankton (6.4-13.8) and planktivorous fish (2.9-5.0)), whereas the ratios were below 1 in seal. The mean ratio between arctic and temperate BAFs for all trophic levels and congeners (BAF(Arcti):BAF(Temperate)) was 4.8. When the data were corrected for the seawater temperature difference between the two ecosystems, the ratio was 2.0. We conclude that bioaccumulation differences caused by ecological or physiological adaptations of organisms between the two ecosystems were well within a water concentration variability of 50%. Further, our data support the hypothesis that lower seawater temperature lead to a thermodynamically favoured passive partitioning to organic matrices and thus elevated ambient BAFs in the Arctic compared to the Baltic Sea. This would imply that bioaccumulation in the Arctic may be described in the same way as bioaccumulation in temperate regions, e.g. by the use of mechanistic models parameterised for the Arctic. Copyright (c) 2010. Published by Elsevier B.V.

  2. A comparison of PCB bioaccumulation factors between an arctic and a temperate marine food web

    International Nuclear Information System (INIS)

    Sobek, Anna; McLachlan, Michael S.; Borga, Katrine; Asplund, Lillemor; Lundstedt-Enkel, Katrin; Polder, Anuschka; Gustafsson, Orjan

    2010-01-01

    To test how environmental conditions in the Arctic and the resulting ecological adaptations affect accumulation of persistent organic pollutants (POPs) in the marine food web, bioaccumulation of four polychlorinated biphenyls (PCBs) in an arctic (Barents Sea 77 o N-82 o N) and a temperate marine (Baltic Sea 54 o N-62 o N) food web were compared. Three different trophic levels were studied (zooplankton, fish, and seal), representing the span from first-level consumer to top predator. Previously published high-quality data on PCB water concentrations in the two areas were used for calculation of bioaccumulation factors (BAF). BAF was calculated as the ratio of the PCB concentration in the organism ([PCB] org ; pg/kg lipid) to the dissolved water concentration (C w ; pg/L). The BAF Arctic :BAF Temperate ratios were above 1 for all four PCB congeners in zooplankton (6.4-13.8) and planktivorous fish (2.9-5.0)), whereas the ratios were below 1 in seal. The mean ratio between arctic and temperate BAFs for all trophic levels and congeners (BAF Arcti :BAF Temperate ) was 4.8. When the data were corrected for the seawater temperature difference between the two ecosystems, the ratio was 2.0. We conclude that bioaccumulation differences caused by ecological or physiological adaptations of organisms between the two ecosystems were well within a water concentration variability of 50%. Further, our data support the hypothesis that lower seawater temperature lead to a thermodynamically favoured passive partitioning to organic matrices and thus elevated ambient BAFs in the Arctic compared to the Baltic Sea. This would imply that bioaccumulation in the Arctic may be described in the same way as bioaccumulation in temperate regions, e.g. by the use of mechanistic models parameterised for the Arctic.

  3. Challenges of climate change: an Arctic perspective.

    Science.gov (United States)

    Corell, Robert W

    2006-06-01

    Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.

  4. History of sea ice in the Arctic

    DEFF Research Database (Denmark)

    Polyak, Leonid; Alley, Richard B.; Andrews, John T.

    2010-01-01

    Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past. This inf......Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past...... Optimum, and consistently covered at least part of the Arctic Ocean for no less than the last 13–14 million years. Ice was apparently most widespread during the last 2–3 million years, in accordance with Earth’s overall cooler climate. Nevertheless, episodes of considerably reduced sea ice or even...

  5. Diatom, cyanobacterial and microbial mats as indicators of hydrocarbon contaminated Arctic streams and waters

    Energy Technology Data Exchange (ETDEWEB)

    Ziervogel, H.; Selann, J.; Adeney, B. [EBA Engineering Consultants Ltd., Edmonton, AB (Canada); Nelson, J.A. [J.B. Services, Sarnia, ON (Canada); Murdock, E. [Nunavut Power, Iqaluit (Canada)

    2003-07-01

    An environmental assessment conducted at Repulse Bay, Nunavut in the summer of 2001 revealed a recent diesel spill flowing from the groundwater into a creek. The spill had not been reported. When Arctic surface waters mix with hydrocarbon impacted groundwater and sediments, distinctive mats of diatom, cyanobacteria and other bacteria are formed. These mats have the potential for phytoremediation of hydrocarbons. This paper explained the apparent dominance of mats in contaminated Arctic waters and why they promote biodegradation of hydrocarbons. Hydrocarbon-contaminated soils and groundwater are generally anaerobic. The higher dissolved carbon dioxide in polluted soils and groundwater can benefit photosynthetic cyanobacteria and diatom found in oligotrophic, lower alkalinity Arctic waters. The anaerobic and aerobic bacteria can potentially take advantage of the hydrogen substrate and the nitrogen fixing abilities of the cyanobacteria. Zooplankton predators may be killed off by the toxicity of the polluted groundwater. The paper provides examples where a microbial mat reduced the sulfate content of a hydrocarbon-impacted Arctic stream by 100 ppm, and where a pond covered in a benthic microbial mat showed no evidence of hydrocarbons in the water overlying sediments contaminated with hydrocarbons at concentrations measured at 30,000 ppm. 19 refs., 3 tabs., 8 figs.

  6. Arctic Glass: Innovative Consumer Technology in Support of Arctic Research

    Science.gov (United States)

    Ruthkoski, T.

    2015-12-01

    The advancement of cyberinfrastructure on the North Slope of Alaska is drastically limited by location-specific conditions, including: unique geophysical features, remoteness of location, and harsh climate. The associated cost of maintaining this unique cyberinfrastructure also becomes a limiting factor. As a result, field experiments conducted in this region have historically been at a technological disadvantage. The Arctic Glass project explored a variety of scenarios where innovative consumer-grade technology was leveraged as a lightweight, rapidly deployable, sustainable, alternatives to traditional large-scale Arctic cyberinfrastructure installations. Google Glass, cloud computing services, Internet of Things (IoT) microcontrollers, miniature LIDAR, co2 sensors designed for HVAC systems, and portable network kits are several of the components field-tested at the Toolik Field Station as part of this project. Region-specific software was also developed, including a multi featured, voice controlled Google Glass application named "Arctic Glass". Additionally, real-time sensor monitoring and remote control capability was evaluated through the deployment of a small cluster of microcontroller devices. Network robustness was analyzed as the devices delivered streams of abiotic data to a web-based dashboard monitoring service in near real time. The same data was also uploaded synchronously by the devices to Amazon Web Services. A detailed overview of solutions deployed during the 2015 field season, results from experiments utilizing consumer sensors, and potential roles consumer technology could play in support of Arctic science will be discussed.

  7. Alkenone-based reconstructions reveal four-phase Holocene temperature evolution for High Arctic Svalbard

    Science.gov (United States)

    van der Bilt, Willem G. M.; D'Andrea, William J.; Bakke, Jostein; Balascio, Nicholas L.; Werner, Johannes P.; Gjerde, Marthe; Bradley, Raymond S.

    2018-03-01

    Situated at the crossroads of major oceanic and atmospheric circulation patterns, the Arctic is a key component of Earth's climate system. Compounded by sea-ice feedbacks, even modest shifts in the region's heat budget drive large climate responses. This is highlighted by the observed amplified response of the Arctic to global warming. Assessing the imprint and signature of underlying forcing mechanisms require paleoclimate records, allowing us to expand our knowledge beyond the short instrumental period and contextualize ongoing warming. However, such datasets are scarce and sparse in the Arctic, limiting our ability to address these issues. Here, we present two quantitative Holocene-length paleotemperature records from the High Arctic Svalbard archipelago, situated in the climatically sensitive Arctic North Atlantic. Temperature estimates are based on U37K unsaturation ratios from sediment cores of two lakes. Our data reveal a dynamic Holocene temperature evolution, with reconstructed summer lake water temperatures spanning a range of ∼6-8 °C, and characterized by four phases. The Early Holocene was marked by an early onset (∼10.5 ka cal. BP) of insolation-driven Hypsithermal conditions, likely compounded by strengthening oceanic heat transport. This warm interval was interrupted by cooling between ∼10.5-8.3 ka cal. BP that we attribute to cooling effects from the melting Northern Hemisphere ice sheets. Temperatures declined throughout the Middle Holocene, following a gradual trend that was accentuated by two cooling steps between ∼7.8-7 ka cal. BP and around ∼4.4-4.3 ka cal. BP. These transitions coincide with a strengthening influence of Arctic water and sea-ice in the adjacent Fram Strait. During the Late Holocene (past 4 ka), temperature change decoupled from the still-declining insolation, and fluctuated around comparatively cold mean conditions. By showing that Holocene Svalbard temperatures were governed by an alternation of forcings, this study

  8. Sensitivity of simulated regional Arctic climate to the choice of coupled model domain

    Directory of Open Access Journals (Sweden)

    Dmitry V. Sein

    2014-07-01

    Full Text Available The climate over the Arctic has undergone changes in recent decades. In order to evaluate the coupled response of the Arctic system to external and internal forcing, our study focuses on the estimation of regional climate variability and its dependence on large-scale atmospheric and regional ocean circulations. A global ocean–sea ice model with regionally high horizontal resolution is coupled to an atmospheric regional model and global terrestrial hydrology model. This way of coupling divides the global ocean model setup into two different domains: one coupled, where the ocean and the atmosphere are interacting, and one uncoupled, where the ocean model is driven by prescribed atmospheric forcing and runs in a so-called stand-alone mode. Therefore, selecting a specific area for the regional atmosphere implies that the ocean–atmosphere system can develop ‘freely’ in that area, whereas for the rest of the global ocean, the circulation is driven by prescribed atmospheric forcing without any feedbacks. Five different coupled setups are chosen for ensemble simulations. The choice of the coupled domains was done to estimate the influences of the Subtropical Atlantic, Eurasian and North Pacific regions on northern North Atlantic and Arctic climate. Our simulations show that the regional coupled ocean–atmosphere model is sensitive to the choice of the modelled area. The different model configurations reproduce differently both the mean climate and its variability. Only two out of five model setups were able to reproduce the Arctic climate as observed under recent climate conditions (ERA-40 Reanalysis. Evidence is found that the main source of uncertainty for Arctic climate variability and its predictability is the North Pacific. The prescription of North Pacific conditions in the regional model leads to significant correlation with observations, even if the whole North Atlantic is within the coupled model domain. However, the inclusion of the

  9. Processes influencing differences in Arctic and Antarctic Trough Mouth Fan sedimentology

    OpenAIRE

    Gales, J; Hillenbrand, C-D; Larter, R; Laberg, J-S; Melles, M; Benetti, S; Passchier, S

    2018-01-01

    Trough Mouth Fans (TMFs) are sediment depocentres that form along high-latitude continental margins at the mouths of some cross-shelf troughs. They reflect the dynamics of past ice sheets over multiple glacial cycles and processes operating on (formerly) glaciated continental shelves and slopes, such as erosion, reworking, transport and deposition. The similarities and differences in TMF morphology and formation processes of the Arctic and Antarctic regions remain poorly constrained. Here, we...

  10. Building Materials in Arctic Climate

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2005-01-01

    Building in the artic requires special attention on the appropriateness of building materials. The harsh climate makes execution difficult and sets unusual requirements for the pure material properties. In addition, there is a lack of choice of good, natural building materials in the arctic...

  11. Mining in the European Arctic

    NARCIS (Netherlands)

    van Dam, Karin; Scheepstra, Adriana; Gille, Johan; Stepien, Adam; Koivurova, Timo; Stepien, Adam; Koivurova, Timo; Kankaanpää, Paula

    The European Arctic has been recently experiencing an upsurge in mining activities. This is reflected in an on-going interest from the industry, regulators and the public. However, current and future prospects are highly sensitive to mineral price fluctuations. The EU is a major consumer and

  12. Computational problems in Arctic Research

    International Nuclear Information System (INIS)

    Petrov, I

    2016-01-01

    This article is to inform about main problems in the area of Arctic shelf seismic prospecting and exploitation of the Northern Sea Route: simulation of the interaction of different ice formations (icebergs, hummocks, and drifting ice floes) with fixed ice-resistant platforms; simulation of the interaction of icebreakers and ice- class vessels with ice formations; modeling of the impact of the ice formations on the underground pipelines; neutralization of damage for fixed and mobile offshore industrial structures from ice formations; calculation of the strength of the ground pipelines; transportation of hydrocarbons by pipeline; the problem of migration of large ice formations; modeling of the formation of ice hummocks on ice-resistant stationary platform; calculation the stability of fixed platforms; calculation dynamic processes in the water and air of the Arctic with the processing of data and its use to predict the dynamics of ice conditions; simulation of the formation of large icebergs, hummocks, large ice platforms; calculation of ridging in the dynamics of sea ice; direct and inverse problems of seismic prospecting in the Arctic; direct and inverse problems of electromagnetic prospecting of the Arctic. All these problems could be solved by up-to-date numerical methods, for example, using grid-characteristic method. (paper)

  13. Arctic resources : a mechatronics opportunity

    Energy Technology Data Exchange (ETDEWEB)

    McKean, M.; Baiden, G. [Penguin Automated Systems Inc., Naughton, ON (Canada)

    2008-07-01

    This paper discussed the telerobotic mechatronics opportunities that exist to access mineral resources in the Arctic. The Mining Automation Project (MAP) determined that telerobotics could contribute to productivity gains while providing increased worker safety. The socio-economic benefits of advanced mechatronics for Arctic resource development are particularly attractive due to reduced infrastructure needs; operating costs; and environmental impacts. A preliminary analysis of mining transportation options by the authors revealed that there is a case for in-situ resource utilization (ISRU) for oil and gas processing to address resource development. The ISRU options build on concepts developed to support space exploration and were proposed to reduce or modify transportation loads to allow more sustainable and efficient Arctic resource development. Many benefits in terms of efficiency could be achieved by combining demonstrated mechatronics with ISRU because of the constrained transportation infrastructure in the Arctic. In the context of harsh environment operations, mechatronics may provide an opportunity for undersea resource facilities. 15 refs., 6 figs.

  14. An AeroCom Assessment of Black Carbon in Arctic Snow and Sea Ice

    Science.gov (United States)

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S. E.; Bellouin, N.; Bernsten, T. K.; Bian, H.; Carslaw, K. S.; Chin, M.; DeLuca, N.; hide

    2014-01-01

    Though many global aerosols models prognose surface deposition, only a few models have been used to directly simulate the radiative effect from black carbon (BC) deposition to snow and sea ice. Here, we apply aerosol deposition fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Models (AeroCom) project to simulate and evaluate within-snow BC concentrations and radiative effect in the Arctic. We accomplish this by driving the offline land and sea ice components of the Community Earth System Model with different deposition fields and meteorological conditions from 2004 to 2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measurements, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are -4.4 (-13.2 to +10.7) ng/g for an earlier phase of AeroCom models (phase I), and +4.1 (-13.0 to +21.4) ng/g for a more recent phase of AeroCom models (phase II), compared to the observational mean of 19.2 ng/g. Factors determining model BC concentrations in Arctic snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation, deposition efficiency of aerosols within the Arctic, and meltwater removal of particles in snow. Sensitivity studies show that the model-measurement evaluation is only weakly affected by meltwater scavenging efficiency because most measurements were conducted in non-melting snow. The Arctic (60-90degN) atmospheric residence time for BC in phase II models ranges from 3.7 to 23.2 days, implying large inter-model variation in local BC deposition efficiency. Combined with the fact that most Arctic BC deposition originates

  15. An AeroCom assessment of black carbon in Arctic snow and sea ice

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S. E.; Bellouin, N.; Berntsen, T. K.; Bian, H.; Carslaw, K. S.; Chin, M.; De Luca, N.; Diehl, T.; Ghan, S. J.; Iversen, T.; Kirkevåg, A.; Koch, D.; Liu, X.; Mann, G. W.; Penner, J. E.; Pitari, G.; Schulz, M.; Seland, Ø.; Skeie, R. B.; Steenrod, S. D.; Stier, P.; Takemura, T.; Tsigaridis, K.; van Noije, T.; Yun, Y.; Zhang, K.

    2014-01-01

    Though many global aerosols models prognose surface deposition, only a few models have been used to directly simulate the radiative effect from black carbon (BC) deposition to snow and sea ice. In this paper, we apply aerosol deposition fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Models (AeroCom) project to simulate and evaluate within-snow BC concentrations and radiative effect in the Arctic. We accomplish this by driving the offline land and sea ice components of the Community Earth System Model with different deposition fields and meteorological conditions from 2004 to 2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measurements, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are -4.4 (-13.2 to +10.7) ng g-1 for an earlier phase of AeroCom models (phase I), and +4.1 (-13.0 to +21.4) ng g-1 for a more recent phase of AeroCom models (phase II), compared to the observational mean of 19.2 ng g-1. Factors determining model BC concentrations in Arctic snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation, deposition efficiency of aerosols within the Arctic, and meltwater removal of particles in snow. Sensitivity studies show that the model–measurement evaluation is only weakly affected by meltwater scavenging efficiency because most measurements were conducted in non-melting snow. The Arctic (60–90° N) atmospheric residence time for BC in phase II models ranges from 3.7 to 23.2 days, implying large inter-model variation in local BC deposition efficiency. Combined with

  16. Sedimentation Deposition Patterns on the Chukchi Shelf Using Radionuclide Inventories

    Science.gov (United States)

    Cooper, L. W.; Grebmeier, J. M.

    2016-02-01

    Sediment core collections and assays of the anthropogenic and natural radioisotopes, 137Cs and 210Pb, respectively, are providing long-term indications of sedimentation and current flow processes on the Chukchi and East Siberian sea continental shelf. This work, which has been integrated into interdisciplinary studies of the Chukchi Sea supported by both the US Bureau of Ocean Energy Management (COMIDA Hanna Shoal Project) and the National Oceanic and Atmospheric Administration (Russian-US Long Term Census of the Arctic, RUSALCA) includes studies of total radiocesium inventories, sedimentation rate determinations, where practical, and depths of maxima in radionuclide deposition. Shallow maxima in the activities of the anthropogenic radionuclide in sediment cores reflect areas with higher current flow (Barrow Canyon and Herald Canyon; 3-6 cm) or low sedimentation (Hanna Shoal; 1-3 cm). The first sedimentation studies from Long Strait are consistent with quiescent current conditions and steady recent sedimentation of clay particles. Elsewhere, higher and more deeply buried radionuclide inventories (> 2 mBq cm-2 at 15-17 cm depth) in the sediments correspond to areas of high particle deposition north of Bering Strait where bioturbation in productive sediments is also clearly an important influence. Radiocesium activities from bomb fallout dating to 1964 are now present at low levels (20 cm. Independent sedimentation rate measurements with the natural radionuclide 210Pb are largely consistent with the radiocesium measurements.

  17. Arctic landfast sea ice

    Science.gov (United States)

    Konig, Christof S.

    Landfast ice is sea ice which forms and remains fixed along a coast, where it is attached either to the shore, or held between shoals or grounded icebergs. Landfast ice fundamentally modifies the momentum exchange between atmosphere and ocean, as compared to pack ice. It thus affects the heat and freshwater exchange between air and ocean and impacts on the location of ocean upwelling and downwelling zones. Further, the landfast ice edge is essential for numerous Arctic mammals and Inupiat who depend on them for their subsistence. The current generation of sea ice models is not capable of reproducing certain aspects of landfast ice formation, maintenance, and disintegration even when the spatial resolution would be sufficient to resolve such features. In my work I develop a new ice model that permits the existence of landfast sea ice even in the presence of offshore winds, as is observed in mature. Based on viscous-plastic as well as elastic-viscous-plastic ice dynamics I add tensile strength to the ice rheology and re-derive the equations as well as numerical methods to solve them. Through numerical experiments on simplified domains, the effects of those changes are demonstrated. It is found that the modifications enable landfast ice modeling, as desired. The elastic-viscous-plastic rheology leads to initial velocity fluctuations within the landfast ice that weaken the ice sheet and break it up much faster than theoretically predicted. Solving the viscous-plastic rheology using an implicit numerical method avoids those waves and comes much closer to theoretical predictions. Improvements in landfast ice modeling can only verified in comparison to observed data. I have extracted landfast sea ice data of several decades from several sources to create a landfast sea ice climatology that can be used for that purpose. Statistical analysis of the data shows several factors that significantly influence landfast ice distribution: distance from the coastline, ocean depth, as

  18. Changing Arctic Ocean freshwater pathways.

    Science.gov (United States)

    Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike

    2012-01-04

    Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

  19. Atmospheric Bromine in the Arctic

    International Nuclear Information System (INIS)

    Berg, W.W.; Sperry, P.D.; Rahn, K.A.; Gladney, E.S.

    1983-01-01

    We report the first measurements of both particulate and gas phase bromine in the Arctic troposphere. Data from continuous sampling of the Arctic aerosol over a period of 4 years (1976--1980) indicate that the bromine content in the aerosol averages 6 +- 4 ngBr/SCM (5 +- 3 pptm Br) for 9 months of every year. During the 3-month period between February 15 and May 15, however, we observed an annual sharp maximum in particulate bromine with levels exceeding 100 ngBr/SCM (82 pptm Br). The Arctic aerosol showed no bromine enrichment relative to seawater except for this 3 month peak period. During the bromine maximum, enrichment factors reached 40 with average values near 10. Calculations of the amount of excess bromine in the Arctic aerosol showed that over 90% of the peak bromine had an origin other than from direct bulk seawater injection. Total levels of gas phase bromine in the Arctic troposphere found during the peak aerosol period averaged 422 +- 48 ngBr/SCM (118 +- 14 pptv). Total bromine content during this period averaged 474 +- 49 ngBr/SCM with gas-to-particle ratios ranging from 7 to 18. A measurement under nonpeak conditions showed total bromine levels at <25 ngBr/SCM. The possibility that local contamination contributed to the seasonal development of the 3-month bromine peak was carefully considered and ruled out. Elevated particualte bromine levels, with peak values ranging from 22 to 30 ngBr/SCM, were also found at Ny-Alesund, Spitsbergen (Norway). The apparent seasonal nature of this bromine peak suggests that the large bromine maximum observed at Barrow is not an isolated or unique phenomenon characteristic of that sampling location

  20. Organic Carbon Delivery from a High-Arctic North American Watershed: Implications for Beaufort Sea Carbon Cycling in a Changing Climate

    Science.gov (United States)

    Schreiner, K. M.; Bruner, V. J.; Kessler, J. D.

    2016-12-01

    Riverine delivery of terrestrial organic carbon (OC) and subsequent burial in coastal margins is a significant sink for OC on Earth. The amount of fresh OC compared to old OC buried in coastal margins affects the long-term ratio of O2 to CO2 in the atmosphere. And yet, the fate of OC on marine shelves is not well known. Analysis of the fate of terrestrial OC from Arctic rivers are especially important, as half of the global soil carbon pool resides in the top few meters of Arctic permafrost soils, and much of this OC, more than twice the amount of carbon currently residing in the atmospheric CO2 pool, is thousands of years old and under threat of disturbance from a warming Arctic climate. Flux of this old, deeply-buried permafrost OC to coastal sediments has already been noted in both the Russian and Alaskan Arctic. This study focuses on OC delivered by the Colville River, a medium-sized North American Arctic river that drains the North Slope of Alaska, and has been previously shown to be an important source of extremely old OC to coastal Beaufort Sea sediments. Here we report stable carbon isotopes and radiocarbon ages of particulate OC (POC), dissolved OC (DOC), and surface sediments from the Beaufort Sea near the Colville River outflow and nearby Simpson Lagoon from samples collected in August 2015. In general, DOC ages are younger than POC ages, and both have stable isotope signatures indicative of terrestrial C3 sources. Waters with higher concentrations of DOC tend to have younger radiocarbon ages and more enriched stable isotope signatures, indicating the presence of aquatic primary production. These data represent some of the first water column radiocarbon signatures to be reported from an Arctic river the size of the Colville; while the six largest Arctic rivers have been well studied over the past few decades, much less data is available for small and medium sized Arctic rivers.

  1. Application of Visible/near Infrared derivative spectroscopy to Arctic paleoceanography

    Science.gov (United States)

    Ortiz, Joseph D.

    2011-05-01

    The lack of well-preserved carbonate in much of the Arctic marine environment dictates the need for alternative methods of paleoceanographic reconstruction. The broad variety of physical properties measurements makes them well suited for use in a variety of environments, but they provide unique opportunities when employed in the Arctic. Because Arctic sediment is introduced and reworked by a variety of mechanisms, the signature from multiple processes becomes intermixed with the sediment. Many of these processes operate in other ocean basins, while some function only in Polar Regions. A strategy to address this mixing problem is to employ spectrally-resolved physical properties measurements, or to use multiple methods in conjunction to generate multivariate data sets, which can differentiate concurrent processes. Data of this type is well suited to multivariate analysis techniques such as sample-based or variable-based, varimax-rotated, principle component analysis (VPCA). These are methods that decompose the data matrix to infer process from orthogonal functions. The method is applied to cores from the Chukchi sea to document that visible derivative spectroscopy provides a powerful means of reconstructing sediment provenance. In the Chukchi Sea, diffuse spectral reflectance provides a proxy to monitor variations in Holocene flow through the Bering Strait.

  2. Application of Visible/near Infrared derivative spectroscopy to Arctic paleoceanography

    International Nuclear Information System (INIS)

    Ortiz, Joseph D

    2011-01-01

    The lack of well-preserved carbonate in much of the Arctic marine environment dictates the need for alternative methods of paleoceanographic reconstruction. The broad variety of physical properties measurements makes them well suited for use in a variety of environments, but they provide unique opportunities when employed in the Arctic. Because Arctic sediment is introduced and reworked by a variety of mechanisms, the signature from multiple processes becomes intermixed with the sediment. Many of these processes operate in other ocean basins, while some function only in Polar Regions. A strategy to address this mixing problem is to employ spectrally-resolved physical properties measurements, or to use multiple methods in conjunction to generate multivariate data sets, which can differentiate concurrent processes. Data of this type is well suited to multivariate analysis techniques such as sample-based or variable-based, varimax-rotated, principle component analysis (VPCA). These are methods that decompose the data matrix to infer process from orthogonal functions. The method is applied to cores from the Chukchi sea to document that visible derivative spectroscopy provides a powerful means of reconstructing sediment provenance. In the Chukchi Sea, diffuse spectral reflectance provides a proxy to monitor variations in Holocene flow through the Bering Strait.

  3. Continental Margins of the Arctic Ocean: Implications for Law of the Sea

    Science.gov (United States)

    Mosher, David

    2016-04-01

    A coastal State must define the outer edge of its continental margin in order to be entitled to extend the outer limits of its continental shelf beyond 200 M, according to article 76 of the UN Convention on the Law of the Sea. The article prescribes the methods with which to make this definition and includes such metrics as water depth, seafloor gradient and thickness of sediment. Note the distinction between the "outer edge of the continental margin", which is the extent of the margin after application of the formula of article 76, and the "outer limit of the continental shelf", which is the limit after constraint criteria of article 76 are applied. For a relatively small ocean basin, the Arctic Ocean reveals a plethora of continental margin types reflecting both its complex tectonic origins and its diverse sedimentation history. These factors play important roles in determining the extended continental shelves of Arctic coastal States. This study highlights the critical factors that might determine the outer edge of continental margins in the Arctic Ocean as prescribed by article 76. Norway is the only Arctic coastal State that has had recommendations rendered by the Commission on the Limits of the Continental Shelf (CLCS). Russia and Denmark (Greenland) have made submissions to the CLCS to support their extended continental shelves in the Arctic and are awaiting recommendations. Canada has yet to make its submission and the US has not yet ratified the Convention. The various criteria that each coastal State has utilized or potentially can utilize to determine the outer edge of the continental margin are considered. Important criteria in the Arctic include, 1) morphological continuity of undersea features, such as the various ridges and spurs, with the landmass, 2) the tectonic origins and geologic affinities with the adjacent land masses of the margins and various ridges, 3) sedimentary processes, particularly along continental slopes, and 4) thickness and

  4. Temperature dependence of microbial degradation of organic matter in marine sediments: polysaccharide hydrolysis, oxygen consumption, and sulfate reduction

    DEFF Research Database (Denmark)

    Arnosti, C.; Jørgensen, BB; Sagemann, J.

    1998-01-01

    temperatures, optimum temperatures generally decreased with decreasing environmental temperatures. Activity at 5 degrees C as a percentage of highest activity was highest in the Arctic sites and lowest in the warmest temperate site. The highest potential rates of substrate hydrolysis were measured...... suggest that organic carbon turnover in the cold Arctic is not intrinsically slower than carbon turnover in temperate environments; sedimentary metabolism in Arctic sediments may be controlled more by organic matter supply than by temperature.......The temperature dependence of representative initial and terminal steps of organic carbon remineralization was measured at 2 temperate sites with annual temperature ranges of 0 to 30 degrees C and 4 to 15 degrees C and 2 Arctic sites with temperatures of 2.6 and -1.7 degrees C. Slurried sediments...

  5. Reactive Nitrogen, Ozone and Ozone Production in the Arctic Troposphere and the Impact of Stratosphere-Troposphere Exchange

    Science.gov (United States)

    Liang, Q.; Rodriquez, J. M.; Douglass, A. R.; Crawford, J. H.; Apel, E.; Bian, H.; Blake, D. R.; Brune, W.; Chin, M.; Colarco, P. R.; hide

    2011-01-01

    We analyze the aircraft observations obtained during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellite (ARCTAS) mission together with the GEOS-5 CO simulation to examine O3 and NOy in the Arctic and sub-Arctic region and their source attribution. Using a number of marker tracers and their probability density distributions, we distinguish various air masses from the background troposphere and examine their contribution to NOx, O3, and O3 production in the Arctic troposphere. The background Arctic troposphere has mean O3 of approximately 60 ppbv and NOx of approximately 25 pptv throughout spring and summer with CO decreases from approximately 145 ppbv in spring to approximately 100 ppbv in summer. These observed CO, NOx and O3 mixing ratios are not notably different from the values measured during the 1988 ABLE-3A and the 2002 TOPSE field campaigns despite the significant changes in the past two decades in processes that could have changed the Arctic tropospheric composition. Air masses associated with stratosphere-troposphere exchange are present throughout the mid and upper troposphere during spring and summer. These air masses with mean O3 concentration of 140-160 ppbv are the most important direct sources of O3 in the Arctic troposphere. In addition, air of stratospheric origin is the only notable driver of net O3 formation in the Arctic due to its sustainable high NOx (75 pptv in spring and 110 pptv in summer) and NOy (approximately 800 pptv in spring and approximately 1100 pptv in summer) levels. The ARCTAS measurements present observational evidence suggesting significant conversion of nitrogen from HNO3 to NOx and then to PAN (a net formation of approximately 120 pptv PAN) in summer when air of stratospheric origin is mixed with tropospheric background during stratosphere-to-troposphere transport. These findings imply that an adequate representation of stratospheric O3 and NOy input are essential in accurately simulating O3

  6. Recent dynamics of arctic and sub-arctic vegetation

    International Nuclear Information System (INIS)

    Epstein, Howard E; Myers-Smith, Isla; Walker, Donald A

    2013-01-01

    We present a focus issue of Environmental Research Letters on the ‘Recent dynamics of arctic and sub-arctic vegetation’. The focus issue includes three perspective articles (Verbyla 2011 Environ. Res. Lett. 6 041003, Williams et al 2011 Environ. Res. Lett. 6 041004, Loranty and Goetz 2012 Environ. Res. Lett. 7 011005) and 22 research articles. The focus issue arose as a result of heightened interest in the response of high-latitude vegetation to natural and anthropogenic changes in climate and disturbance regimes, and the consequences that these vegetation changes might have for northern ecosystems. A special session at the December 2010 American Geophysical Union Meeting on the ‘Greening of the Arctic’ spurred the call for papers. Many of the resulting articles stem from intensive research efforts stimulated by International Polar Year projects and the growing acknowledgment of ongoing climate change impacts in northern terrestrial ecosystems. (synthesis and review)

  7. The changing seasonal climate in the Arctic.

    Science.gov (United States)

    Bintanja, R; van der Linden, E C

    2013-01-01

    Ongoing and projected greenhouse warming clearly manifests itself in the Arctic regions, which warm faster than any other part of the world. One of the key features of amplified Arctic warming concerns Arctic winter warming (AWW), which exceeds summer warming by at least a factor of 4. Here we use observation-driven reanalyses and state-of-the-art climate models in a variety of standardised climate change simulations to show that AWW is strongly linked to winter sea ice retreat through the associated release of surplus ocean heat gained in summer through the ice-albedo feedback (~25%), and to infrared radiation feedbacks (~75%). Arctic summer warming is surprisingly modest, even after summer sea ice has completely disappeared. Quantifying the seasonally varying changes in Arctic temperature and sea ice and the associated feedbacks helps to more accurately quantify the likelihood of Arctic's climate changes, and to assess their impact on local ecosystems and socio-economic activities.

  8. Potential for an Arctic-breeding migratory bird to adjust spring migration phenology to Arctic amplification

    NARCIS (Netherlands)

    Lameris, T.K.; Scholten, Ilse; Bauer, S.; Cobben, M.M.P.; Ens, B.J.; Nolet, B.A.

    2017-01-01

    Arctic amplification, the accelerated climate warming in the polar regions, is causing a more rapid advancement of the onset of spring in the Arctic than in temperate regions. Consequently, the arrival of many migratory birds in the Arctic is thought to become increasingly mismatched with the onset

  9. Arctic whaling : proceedings of the International Symposium Arctic Whaling February 1983

    NARCIS (Netherlands)

    Jacob, H.K. s'; Snoeijing, K

    1984-01-01

    Contents: D.M. Hopkins and Louie Marincovich Jr. Whale Biogeography and the history of the Arctic Basin P.M. Kellt, J.H.W. Karas and L.D. Williams Arctic Climate: Past, Present and Future Torgny E. Vinje On the present state and the future fate of the Arctic sea ice cover P.J.H. van Bree On the

  10. Marine Corps Equities in the Arctic

    Science.gov (United States)

    2013-04-18

    reduces the shipping time from Yokohama, Japan, to Hamburg , Germany, by 11 days as compared to the Suez Canal. Ships average approximately a 20...areas within the Arctic Circle. 10 Warming ocean water is causing fisheries to shift north as well. Fish populations usually found in the...people live in the Arctic region. Commercial fishing fleets are following these populations. 29 Russia holds the majority of the Arctic population

  11. The International Arctic Seas Assessment Project

    International Nuclear Information System (INIS)

    Linsley, G.S.; Sjoeblom, K.L.

    1994-01-01

    The International Arctic Seas Assessment Project (IASAP) was initiated in 1993 to address widespread concern over the possible health and environmental impacts associated with the radioactive waste dumped into the shallow waters of the Arctic Seas. This article discusses the project with these general topics: A brief history of dumping activities; the international control system; perspectives on arctic Seas dumping; the IASAP aims and implementation; the IASAP work plan and progress. 2 figs

  12. Nudging the Arctic Ocean to quantify Arctic sea ice feedbacks

    Science.gov (United States)

    Dekker, Evelien; Severijns, Camiel; Bintanja, Richard

    2017-04-01

    It is well-established that the Arctic is warming 2 to 3 time faster than rest of the planet. One of the great uncertainties in climate research is related to what extent sea ice feedbacks amplify this (seasonally varying) Arctic warming. Earlier studies have analyzed existing climate model output using correlations and energy budget considerations in order to quantify sea ice feedbacks through indirect methods. From these analyses it is regularly inferred that sea ice likely plays an important role, but details remain obscure. Here we will take a different and a more direct approach: we will keep the sea ice constant in a sensitivity simulation, using a state-of -the-art climate model (EC-Earth), applying a technique that has never been attempted before. This experimental technique involves nudging the temperature and salinity of the ocean surface (and possibly some layers below to maintain the vertical structure and mixing) to a predefined prescribed state. When strongly nudged to existing (seasonally-varying) sea surface temperatures, ocean salinity and temperature, we force the sea ice to remain in regions/seasons where it is located in the prescribed state, despite the changing climate. Once we obtain fixed' sea ice, we will run a future scenario, for instance 2 x CO2 with and without prescribed sea ice, with the difference between these runs providing a measure as to what extent sea ice contributes to Arctic warming, including the seasonal and geographical imprint of the effects.

  13. Effects of sediment organic matter quality on bioaccumulation, degradation, and distribution of pyrene in two macrofaunal species and their surrounding sediment

    DEFF Research Database (Denmark)

    Granberg, Maria E.; Selck, Henriette

    2007-01-01

    Sediment dwelling macrofauna (infauna) are important vectors for the transfer of sediment-associated contaminants to higher trophic levels. Sedimenting organic matter constitutes an important food source for all benthic organisms and changes seasonally in terms of quantity and quality. Sediment...... imply that bioaccumulation and trophic transfer of sediment-associated PAH should increase following fresh organic matter input, e.g. after sedimentation of phytoplankton blooms. We stress the importance of considering behavioural characteristics of infauna and the trophic situation of the system when...

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

    Science.gov (United States)

    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

  15. The Holocene history of Nares Strait: Transition from glacial bay to Arctic-Atlantic throughflow

    Science.gov (United States)

    Jennings, Anne E.; Sheldon, Christina; Cronin, Thomas M.; Francus, Pierre; Stoner, Joseph; Andrews, John

    2011-01-01

    Retreat of glacier ice from Nares Strait and other straits in the Canadian Arctic Archipelago after the end of the last Ice Age initiated an important connection between the Arctic and the North Atlantic Oceans, allowing development of modern ocean circulation in Baffin Bay and the Labrador Sea. As low-salinity, nutrient-rich Arctic Water began to enter Baffin Bay, it contributed to the Baffin and Labrador currents flowing southward. This enhanced freshwater inflow must have influenced the sea ice regime and likely is responsible for poor calcium carbonate preservation that characterizes the Baffin Island margin today. Sedimentologic and paleoceanographic data from radiocarbon-dated core HLY03-05GC, Hall Basin, northern Nares Strait, document the timing and paleoenvironments surrounding the retreat of waning ice sheets from Nares Strait and opening of this connection between the Arctic Ocean and Baffin Bay. Hall Basin was deglaciated soon before 10,300 cal BP (calibrated years before present) and records ice-distal sedimentation in a glacial bay facing the Arctic Ocean until about 9,000 cal BP. Atlantic Water was present in Hall Basin during deglaciation, suggesting that it may have promoted ice retreat. A transitional unit with high ice-rafted debris content records the opening of Nares Strait at approximately 9,000 cal BP. High productivity in Hall Basin between 9,000 and 6,000 cal BP reflects reduced sea ice cover and duration as well as throughflow of nutrient-rich Pacific Water. The later Holocene is poorly resolved in the core, but slow sedimentation rates and heavier carbon isotope values support an interpretation of increased sea ice cover and decreased productivity during the Neoglacial period.

  16. Regional cooperation and sustainable development: The Arctic

    International Nuclear Information System (INIS)

    Vartanov, R.V.

    1993-01-01

    The Arctic is one of the regions most alienated from sustainable development, due to consequences of nuclear testing, long-range pollution transport, large-scale industrial accidents, irrational use of natural resources, and environmentally ignorant socio-economic policies. Revelations of the state of the USSR Arctic shows that air quality in northern cities is below standard, fish harvests are declining, pollution is not being controlled, and native populations are being affected seriously. The presence of immense resources in the Arctic including exploitable offshore oil reserves of 100-200 billion bbl and the prospect of wider utilization of northern sea routes should stimulate establishment of a new international regime of use, research, and protection of Arctic resources in favor of sustainable development in the region. The Arctic marine areas are the key component of the Arctic ecosystem and so should receive special attention. A broad legal framework has already been provided for such cooperation. Included in such cooperation would be native peoples and non-Arctic countries. Specifics of the cooperation would involve exchanging of scientific and technical information, promotion of ecologically sound technologies, equipping Arctic regions with means to control environmental quality, harmonizing environmental protection legislation, and monitoring Arctic environmental quality

  17. Arctic Research Plan: FY2017-2021

    Science.gov (United States)

    Starkweather, Sandy; Jeffries, Martin O; Stephenson, Simon; Anderson, Rebecca D.; Jones, Benjamin M.; Loehman, Rachel A.; von Biela, Vanessa R.

    2016-01-01

    The United States is an Arctic nation—Americans depend on the Arctic for biodiversity and climate regulation and for natural resources. America’s Arctic—Alaska—is at the forefront of rapid climate, environmental, and socio-economic changes that are testing the resilience and sustainability of communities and ecosystems. Research to increase fundamental understanding of these changes is needed to inform sound, science-based decision- and policy-making and to develop appropriate solutions for Alaska and the Arctic region as a whole. Created by an Act of Congress in 1984, and since 2010 a subcommittee of the National Science and Technology Council (NSTC) in the Executive Office of the President, the Interagency Arctic Research Policy Committee (IARPC) plays a critical role in advancing scientific knowledge and understanding of the changing Arctic and its impacts far beyond the boundaries of the Arctic. Comprising 14 Federal agencies, offices, and departments, IARPC is responsible for the implementation of a 5-year Arctic Research Plan in consultation with the U.S. Arctic Research Commission, the Governor of the State of Alaska, residents of the Arctic, the private sector, and public interest groups.

  18. Immune function in arctic mammals

    DEFF Research Database (Denmark)

    Desforges, Jean-Pierre; Jasperse, Lindsay; Jensen, Trine Hammer

    2018-01-01

    Natural killer (NK) cells are a vital part of the rapid and non-specific immune defense against invading pathogens and tumor cells. This study evaluated NK cell-like activity by flow cytometry for the first time in three ecologically and culturally important Arctic mammal species: polar bear (Ursus...... the effector:target cell ratio increased. Comparing NK activity between fresh and cryopreserved mouse lymphocytes revealed little to no difference in function, highlighting the applicability of cryopreserving cells in field studies. The evaluation of this important innate immune function in Arctic mammals can...... contribute to future population health assessments, especially as pollution-induced suppression of immune function may increase infectious disease susceptibility....

  19. The Influence of Sea Ice on Arctic Low Cloud Properties and Radiative Effects

    Science.gov (United States)

    Taylor, Patrick C.

    2015-01-01

    The Arctic is one of the most climatically sensitive regions of the Earth. Climate models robustly project the Arctic to warm 2-3 times faster than the global mean surface temperature, termed polar warming amplification (PWA), but also display the widest range of surface temperature projections in this region. The response of the Arctic to increased CO2 modulates the response in tropical and extra-tropical regions through teleconnections in the atmospheric circulation. An increased frequency of extreme precipitation events in the northern mid-latitudes, for example, has been linked to the change in the background equator-to-pole temperature gradient implied by PWA. Understanding the Arctic climate system is therefore important for predicting global climate change. The ice albedo feedback is the primary mechanism driving PWA, however cloud and dynamical feedbacks significantly contribute. These feedback mechanisms, however, do not operate independently. How do clouds respond to variations in sea ice? This critical question is addressed by combining sea ice, cloud, and radiation observations from satellites, including CERES, CloudSAT, CALIPSO, MODIS, and microwave radiometers, to investigate sea ice-cloud interactions at the interannual timescale in the Arctic. Cloud characteristics are strongly tied to the atmospheric dynamic and thermodynamic state. Therefore, the sensitivity of Arctic cloud characteristics, vertical distribution and optical properties, to sea ice anomalies is computed within atmospheric dynamic and thermodynamic regimes. Results indicate that the cloud response to changes in sea ice concentration differs significantly between atmospheric state regimes. This suggests that (1) the atmospheric dynamic and thermodynamic characteristics and (2) the characteristics of the marginal ice zone are important for determining the seasonal forcing by cloud on sea ice variability.

  20. Physiological Adaptations of Arctic Mammals.

    Science.gov (United States)

    1975-01-01

    Katie Persons, Biologist Peter ’Ringens, Biochemist Oliver Heroux, Ph.D., Physiologist Edward Koo, Biologist Martin Steiner, Biologist Louise Janes...and aspects . This manuscript includes about one-fifth of our data on this topic, obtained in the last two years. Of course, my motivation for studying...ARCTIC LEIMINGS Progressive depression of renal function during hypo- thermia generally is presupposed. Data gathered incidentally as part of a

  1. Arctic bioremediation -- A case study

    International Nuclear Information System (INIS)

    Smallbeck, D.R.; Ramert, P.C.; Liddell, B.V.

    1994-01-01

    This paper discusses the use of bioremediation as an effective method to clean up diesel-range hydrocarbon spills in northern latitudes. The results of a laboratory study of microbial degradation of hydrocarbons under simulated arctic conditions showed that bioremediation can be effective in cold climates and led to the implementation of a large-scale field program. The results of 3 years of field testing have led to a significant reduction in diesel-range hydrocarbon concentrations in the contaminated area

  2. The gap in the Arctic Cenozoic Record: Expect the Unexpected

    Science.gov (United States)

    Sangiorgi, F.; Brumsack, H.; Schouten, S.; Brinkhuis, H.; Kaminski, M. A.; Reichart, G.; Stickley, C. E.; Willard, D. A.; Sinninghe Damste', J. S.

    2006-12-01

    Integrated Ocean Drilling Program Expedition 302, a.k.a. the Arctic Coring Expedition (ACEX), drilled more than 400 meters below the seafloor at the central Lomonosov Ridge, ca 250 km from the modern North Pole in water depths of about 1300 m. The partially recovered sediments provide a unique record of the geological and paleoceanographical evolution of the Arctic Ocean during the Cenozoic. The record indicates a transition from a "greenhouse world", characterized by a relative shallow marine setting, with organic-rich sediment and frequent brackish or even fresh surface waters during the latest Palaeocene and the early Eocene, to an "icehouse world" of hemipelagic sedimentation affected by the occurrence of sea ice from the middle Miocene to present. Much to our surprise, these two states are separated by a major hiatus, not obvious from the seismic record and the lithology of the cores, spanning at least 25 Ma as derived from dinocyst and benthic foraminifer stratigraphies. These testify that deposits of probable late early Miocene age directly overlie early middle Eocene sediments. To unravel the nature of the hiatus, we performed a multiproxy micropaleontological and geochemical study on the surrounding record, i.e. lithological units 1/6, 1/5 and 1/4, where the sediment changes from homogeneous dark into a cm-scaled alternation ("zebra-like") black and grey bands to light grey, blue and reddish-brown. Paleoenvironmental reconstructions based on organic-walled dinoflagellate cysts, pollen and spores, benthic foraminifera, inorganic and organic geochemistry and siliceous remains reveal conspicuous changes, suggesting a transition from brackish-freshwater to shallow-lagoonal and to open marine environments. These environmental turnovers, coupled with the occurrence of such a large hiatus, cannot be due to climatic shifts alone, but suggest that major tectonic rearrangements likely changed the depositional setting. On-going organic geochemical analysis will be

  3. Arctic adaptation and climate change

    International Nuclear Information System (INIS)

    Agnew, T.A.; Headley, A.

    1994-01-01

    The amplification of climatic warming in the Arctic and the sensitivity of physical, biological, and human systems to changes in climate make the Arctic particularly vulnerable to climate changes. Large areas of the Arctic permafrost and sea ice are expected to disappear under climate warming and these changes will have considerable impacts on the natural and built environment of the north. A review is presented of some recent studies on what these impacts could be for the permafrost and sea ice environment and to identify linkages with socioeconomic activities. Terrestrial adaptation to climate change will include increases in ground temperature; melting of permafrost with consequences such as frost heave, mudslides, and substantial settlement; rotting of peat contained in permafrost areas, with subsequent emission of CO 2 ; increased risk of forest fire; and flooding of low-lying areas. With regard to the manmade environment, structures that will be affected include buildings, pipelines, highways, airports, mines, and railways. In marine areas, climate change will increase the ice-free period for marine transport operations and thus provide some benefit to the offshore petroleum industry. This benefit will be offset by increased wave height and period, and increased coastal erosion. The offshore industry needs to be particularly concerned with these impacts since the expected design life of industry facilities (30-60 y) is of the same order as the time frame for possible climatic changes. 18 refs., 5 figs

  4. Nesting ecology of Arctic loons

    Science.gov (United States)

    Petersen, Margaret R.

    1979-01-01

    Arctic Loons were studied on the Yukon-Kuskokwim Delta, Alaska, from the time of their arrival in May to their departure in September, in 1974 and 1975. Pairs arrived on breeding ponds as soon as sufficient meltwater was available to allow their take-off and landing. Loons apparently do not initiate nests immediately after their arrival, even when nest-sites are available. Delayed egg-laying may be dependent on a period of yolk formation. Delaying yolk formation until after arrival on nest ponds is an adaptation by loons to the variable time suitable habitat becomes available for nesting. Predation of eggs by Glaucous Gulls, Long-tailed and Parasitic jaegers and foxes varied in relation to the location of the nest-site, and the availability of alternate prey. Hatching success was the lowest recorded for Arctic Loons (5%) in 1974, when eggs of both loons and Cackling Geese were taken in large numbers by predators. Hatching success increased to 32% in 1975 when an abundance of tundra voles was observed. No loon eggs hatched after the hatching of the Cackling Goose eggs when this alternate prey was no longer available. Nests destroyed by foxes were predominantly along shorelines, and those by gulls and jaegers were predominantly on islands. Nest-site selection by Arctic Loons may reflect an adaptive response to varying selective pressures by their predators.

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

    Science.gov (United States)

    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. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  6. Projected Regime Shift in Arctic Cloud and Water Vapor Feedbacks

    Science.gov (United States)

    Chen, Yonghua; Miller, James R.; Francis, Jennifer; Russel, Gary L.

    2011-01-01

    The Arctic climate is changing faster than any other large-scale region on Earth. A variety of positive feedback mechanisms are responsible for the amplification, most of which are linked with changes in snow and ice cover, surface temperature (T(sub s)), atmospheric water vapor (WV), and cloud properties. As greenhouse gases continue to accumulate in the atmosphere, air temperature and water vapor content also increase, leading to a warmer surface and ice loss, which further enhance evaporation and WV. Many details of these interrelated feedbacks are poorly understood, yet are essential for understanding the pace and regional variations in future Arctic change. We use a global climate model (Goddard Institute for Space Studies, Atmosphere-Ocean Model) to examine several components of these feedbacks, how they vary by season, and how they are projected to change through the 21st century. One positive feedback begins with an increase in T(sub s) that produces an increase in WV, which in turn increases the downward longwave flux (DLF) and T(sub s), leading to further evaporation. Another associates the expected increases in cloud cover and optical thickness with increasing DLF and T(sub s). We examine the sensitivities between DLF and other climate variables in these feedbacks and find that they are strongest in the non-summer seasons, leading to the largest amplification in Ts during these months. Later in the 21st century, however, DLF becomes less sensitive to changes in WV and cloud optical thickness, as they cause the atmosphere to emit longwave radiation more nearly as a black body. This regime shift in sensitivity implies that the amplified pace of Arctic change relative to the northern hemisphere could relax in the future.

  7. Arctic shelves as platforms for biogeochemical activity: Nitrogen and carbon transformations in the Chukchi Sea, Alaska

    Science.gov (United States)

    Hardison, Amber K.; McTigue, Nathan D.; Gardner, Wayne S.; Dunton, Kenneth H.

    2017-10-01

    Continental shelves comprise 50% of marine denitrification. The Hanna Shoal region, part of the continental shelf system in the northeast Chukchi Sea, Alaska, is recognized for its high biodiversity and productivity. We investigated the role of sediments in organic matter decomposition and nutrient cycling at five stations on the shallow Hanna Shoal. In particular, we asked (1) how much sediment organic matter is remineralized in the Chukchi Sea, and what factors drive this degradation, (2) do sediments function as a net source for fixed nitrogen (thus fueling primary production in the overlying water), or as a net sink for fixed nitrogen (thereby removing it from the system), and (3) what is the balance between sediment NH4+ uptake and regeneration, and what factors drive NH4+ cycling? We conducted dark sediment core incubations to measure sediment O2 consumption, net N2 and nutrient (NH4+, NO3-, NO2-, PO43-) fluxes, and rates of sediment NH4+ cycling, including uptake and regeneration. Rates of sediment O2 consumption and NH4+ and PO43- efflux suggest that high organic matter remineralization rates occurred in these cold (-2 °C) sediments. We estimated that total organic carbon remineralization accounted for 20-57% of summer export production measured on the Chukchi Shelf. Net N2 release was the dominant nitrogen flux, indicating that sediments acted as a net sink for bioavailable nitrogen via denitrification. Organic carbon remineralization via denitrification accounted for 6-12% of summer export production, which made up 25% of the total organic carbon oxidized in Hanna Shoal sediments. These shallow, productive Arctic shelves are ;hotspots; for organic matter remineralization.

  8. The Arctic Observing Network (AON)Cooperative Arctic Data and Information Service (CADIS)

    Science.gov (United States)

    Moore, J.; Fetterer, F.; Middleton, D.; Ramamurthy, M.; Barry, R.

    2007-12-01

    are compatible with international standards, and on demonstrating data submission, search and visualization tools with a subset of AON data. These capabilities will be expanded in years 2 and 3. By working with AON investigators and by using evolving conventions for in situ data formats as they mature, we hope to bring CADIS to the full level of data integration imagined by AON planners. The CADIS development will be described in terms of challenges, implementation strategies and progress to date. The developers are making a conscious effort to integrate this system and its data holdings with the complementary efforts in the SEARCH and IPY programs. The interdisciplinary content of the data, the variations in format and documentation, as well as its geographic coverage across the Arctic Basin all impact the form and effectiveness of the CADIS system architecture. The clever solutions to the complexity of implementing a comprehensive data management strategy implied in this diversity will be a focus of the presentation.

  9. An atmosphere-ocean GCM modelling study of the climate response to changing Arctic seaways in the early Cenozoic.

    Science.gov (United States)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2008-12-01

    The report of fossil Azolla (a freshwater aquatic fern) in sediments from the Lomonosov Ridge suggests low salinity conditions occurred in the Arctic Ocean in the early Eocene. Restricted passages between the Arctic Ocean and the surrounding oceans are hypothesized to have caused this Arctic freshening. We investigate this scenario using a water-isotope enabled atmosphere-ocean general circulation model with Eocene boundary conditions including 4xCO2, 7xCH4, altered bathymetry and topography, and an estimated distribution of Eocene vegetational types. In one experiment, oceanic exchange between the Arctic Ocean and other ocean basins was restricted to two shallow (~250 m) seaways, one in the North Atlantic, the Greenland-Norwegian seaway, and the second connecting the Arctic Ocean with the Tethys Ocean, the Turgai Straits. In the restricted configuration, the Greenland-Norwegian seaway was closed and exchange through the Turgai Straits was limited to a depth of ~60 m. The simulations suggest that the severe restriction of Arctic seaways in the early Eocene may have been sufficient to freshen Arctic Ocean surface waters, conducive to Azolla blooms. When exchange with the Arctic Ocean is limited, salinities in the upper several hundred meters of the water column decrease by ~10 psu. In some regions, surface salinity is within 2-3 psu of the reported maximum modern conditions tolerated by Azolla (~5 psu). In the restricted scenario, salt is stored preferentially in the North Atlantic and Tethys oceans, resulting in enhanced meridional overturning, increased poleward heat transport in the North Atlantic western boundary current, and warming of surface and intermediate waters in the North Atlantic by several degrees. Increased sensible and latent heat fluxes from the North Atlantic Ocean, combined with a reduction in cloud albedo, also lead to an increase in surface air temperature of over much of North America, Greenland and Eurasia. Our work is consistent with

  10. Seasonal dynamics of bacterial biomass and production in a coastal arctic ecosystem: Franklin Bay, western Canadian Arctic

    Science.gov (United States)

    Garneau, Marie-Ã. Ve; Roy, SéBastien; Lovejoy, Connie; Gratton, Yves; Vincent, Warwick F.

    2008-07-01

    The Canadian Arctic Shelf Exchange Study (CASES) included the overwintering deployment of a research platform in Franklin Bay (70°N, 126°W) and provided a unique seasonal record of bacterial dynamics in a coastal region of the Arctic Ocean. Our objectives were (1) to relate seasonal bacterial abundance (BA) and production (BP) to physico-chemical characteristics and (2) to quantify the annual bacterial carbon flux. BA was estimated by epifluorescence microscopy and BP was estimated from 3H-leucine and 3H-thymidine assays. Mean BA values for the water column ranged from 1.0 (December) to 6.8 × 105 cells mL-1 (July). Integral BP varied from 1 (February) to 80 mg C m-2 d-1 (July). During winter-spring, BP was uncorrelated with chlorophyll a (Chl a), but these variables were significantly correlated during summer-autumn (rs = 0.68, p winter, late winter-late spring, and summer. A baseline level of BB and BP was maintained throughout late winter-late spring despite the persistent cold and darkness, with irregular fluctuations that may be related to hydrodynamic events. During this period, BP rates were correlated with colored dissolved organic matter (CDOM) but not Chl a (rs BP.CDOM∣Chl a = 0.20, p < 0.05, N = 176). Annual BP was estimated as 6 g C m-2 a-1, implying a total BP of 4.8 × 1010 g C a-1 for the Franklin Bay region. These results show that bacterial processes continue throughout all seasons and make a large contribution to the total biological carbon flux in this coastal arctic ecosystem.

  11. Connecting Arctic Research Across Boundaries through the Arctic Research Consortium of the United States (ARCUS)

    Science.gov (United States)

    Rich, R. H.; Myers, B.; Wiggins, H. V.; Zolkos, J.

    2017-12-01

    The complexities inherent in Arctic research demand a unique focus on making connections across the boundaries of discipline, institution, sector, geography, knowledge system, and culture. Since 1988, ARCUS has been working to bridge these gaps through communication, coordination, and collaboration. Recently, we have worked with partners to create a synthesis of the Arctic system, to explore the connectivity across the Arctic research community and how to strengthen it, to enable the community to have an effective voice in research funding policy, to implement a system for Arctic research community knowledge management, to bridge between global Sea Ice Prediction Network researchers and the science needs of coastal Alaska communities through the Sea Ice for Walrus Outlook, to strengthen ties between Polar researchers and educators, and to provide essential intangible infrastructure that enables cost-effective and productive research across boundaries. Employing expertise in managing for collaboration and interdisciplinarity, ARCUS complements and enables the work of its members, who constitute the Arctic research community and its key stakeholders. As a member-driven organization, everything that ARCUS does is achieved through partnership, with strong volunteer leadership of each activity. Key organizational partners in the United States include the U.S. Arctic Research Commission, Interagency Arctic Research Policy Committee, National Academy of Sciences Polar Research Board, and the North Slope Science Initiative. Internationally, ARCUS maintains strong bilateral connections with similarly focused groups in each Arctic country (and those interested in the Arctic), as well as with multinational organizations including the International Arctic Science Committee, the Association of Polar Early Career Educators, the University of the Arctic, and the Arctic Institute of North America. Currently, ARCUS is applying the best practices of the science of team science

  12. The transformation and fate of sub-Arctic microphytobenthos carbon revealed through 13C-labeling

    DEFF Research Database (Denmark)

    Oakes, Joanne M.; Rysgaard, Søren; Glud, Ronnie N.

    2016-01-01

    Microphytobenthos (MPB) at higher latitudes has been poorly studied. This study used pulse-chase C-13-labeling to investigate the production, processing, and fate of MPB-derived carbon (MPB-C) in sub-Arctic intertidal sediments over 31 d. Gross primary production (2.1 mmolCm(-2)h(-1)+/- 0.4 mmol...... accounted for49.8% of this C-13. The C-13 content of sediment organic carbon declined over time, but>31% of the C-13 fixed within the first tidal cycle remained after 31 d, suggesting that sub-Arctic MPB may contribute to coastal carbon retention during the productive season. Over 21 d, 10.6% of the fixed C......-13 was removed via DIC fluxes and 0.3% via DOC fluxes from inundated sediment, and 0.6% as CO2 from exposed sediment. The greatest loss of C-13 (38.2%) was via unmeasured pathways, including resuspension and/or removal by mobile consumers. The rates of MPB-C production and the relative importance...

  13. Plutonium in the Arctic Marine Environment — A Short Review

    Directory of Open Access Journals (Sweden)

    Lindis Skipperud

    2004-01-01

    Full Text Available Anthropogenic plutonium has been introduced into the environment over the past 50 years as the result of the detonation of nuclear weapons and operational releases from the nuclear industry. In the Arctic environment, the main source of plutonium is from atmospheric weapons testing, which has resulted in a relatively uniform, underlying global distribution of plutonium. Previous studies of plutonium in the Kara Sea have shown that, at certain sites, other releases have given rise to enhanced local concentrations. Since different plutonium sources are characterised by distinctive plutonium-isotope ratios, evidence of a localised influence can be supported by clear perturbations in the plutonium-isotope ratio fingerprints as compared to the known ratio in global fallout. In Kara Sea sites, such perturbations have been observed as a result of underwater weapons tests at Chernaya Bay, dumped radioactive waste in Novaya Zemlya, and terrestrial runoff from the Ob and Yenisey Rivers. Measurement of the plutonium-isotope ratios offers both a means of identifying the origin of radionuclide contamination and the influence of the various nuclear installations on inputs to the Arctic, as well as a potential method for following the movement of water and sediment loads in the rivers.

  14. Plutonium in the arctic marine environment--a short review.

    Science.gov (United States)

    Skipperud, Lindis

    2004-06-18

    Anthropogenic plutonium has been introduced into the environment over the past 50 years as the result of the detonation of nuclear weapons and operational releases from the nuclear industry. In the Arctic environment, the main source of plutonium is from atmospheric weapons testing, which has resulted in a relatively uniform, underlying global distribution of plutonium. Previous studies of plutonium in the Kara Sea have shown that, at certain sites, other releases have given rise to enhanced local concentrations. Since different plutonium sources are characterised by distinctive plutonium-isotope ratios, evidence of a localised influence can be supported by clear perturbations in the plutonium-isotope ratio fingerprints as compared to the known ratio in global fallout. In Kara Sea sites, such perturbations have been observed as a result of underwater weapons tests at Chernaya Bay, dumped radioactive waste in Novaya Zemlya, and terrestrial runoff from the Ob and Yenisey Rivers. Measurement of the plutonium-isotope ratios offers both a means of identifying the origin of radionuclide contamination and the influence of the various nuclear installations on inputs to the Arctic, as well as a potential method for following the movement of water and sediment loads in the rivers.

  15. Atlantic water heat transfer through the Arctic Gateway (Fram Strait) during the Last Interglacial

    Science.gov (United States)

    Zhuravleva, Anastasia; Bauch, Henning A.; Spielhagen, Robert F.

    2017-10-01

    The Last Interglacial in the Arctic region is often described as a time with warmer conditions and significantly less summer sea ice than today. The role of Atlantic water (AW) as the main oceanic heat flux agent into the Arctic Ocean remains, however, unclear. Using high-resolution stable isotope and faunal records from the only deep Arctic Gateway, the Fram Strait, we note for the upper water column a diminished influence of AW and generally colder-than-Holocene surface ocean conditions. After the main Saalian deglaciation had terminated, a first intensification of northward-advected AW happened ( 124 ka). However, an intermittent sea surface cooling, triggered by meltwater release at 122 ka, caused a regional delay in the further development towards peak interglacial conditions. Maximum AW heat advection occurred during late MIS 5e (118.5-116 ka) and interrupted a longer-term cooling trend at the sea surface that started from about 120 ka on. Such a late occurrence of the major AW-derived near-surface warming in the Fram Strait - this is in stark contrast to an early warm peak in the Holocene - compares well in time with upstream records from the Norwegian Sea, altogether implying a coherent development of south-to-north ocean heat transfer through the eastern Nordic Seas and into the high Arctic during the Last Interglacial.

  16. Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

    Science.gov (United States)

    Lenz, Josefine; Jones, Benjamin M.; Wetterich, Sebastian; Tjallingii, Rik; Fritz, Michael; Arp, Christopher D.; Rudaya, Natalia; Grosse, Guido

    2016-01-01

    Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation, and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological, and geochemical proxies. Radiocarbon and 210Pb/137Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of ~1400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the “alder high” that occurred in the region ~4000 cal yr BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were, therefore, archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

  17. International Regulation of Central Arctic Ocean Fisheries

    NARCIS (Netherlands)

    Molenaar, E.J.

    Due in particular to the impacts of climate change, the adequacy of the international regulation of Central Arctic Ocean fisheries has come under increasing scrutiny in recent years. As shown in this article, however, international regulation of Central Arctic Ocean fisheries is by no means entirely

  18. Pacific Northwest Laboratory Alaska (ARCTIC) research program

    International Nuclear Information System (INIS)

    Hanson, W.C.; Eberhardt, L.E.

    1980-03-01

    The current program continues studies of arctic ecosystems begun in 1959 as part of the Cape Thompson Program. Specific ecosystem aspects include studies of the ecology of arctic and red foxes, small mammel and bird population studies, lichen studies, and radiation ecology studies

  19. A Recommended Set of Key Arctic Indicators

    Science.gov (United States)

    Stanitski, D.; Druckenmiller, M.; Fetterer, F. M.; Gerst, M.; Intrieri, J. M.; Kenney, M. A.; Meier, W.; Overland, J. E.; Stroeve, J.; Trainor, S.

    2017-12-01

    The Arctic is an interconnected and environmentally sensitive system of ice, ocean, land, atmosphere, ecosystems, and people. From local to pan-Arctic scales, the area has already undergone major changes in physical and societal systems and will continue at a pace that is greater than twice the global average. Key Arctic indicators can quantify these changes. Indicators serve as the bridge between complex information and policy makers, stakeholders, and the general public, revealing trends and information people need to make important socioeconomic decisions. This presentation evaluates and compiles more than 70 physical, biological, societal and economic indicators into an approachable summary that defines the changing Arctic. We divided indicators into "existing," "in development," "possible," and "aspirational". In preparing a paper on Arctic Indicators for a special issue of the journal Climatic Change, our group established a set of selection criteria to identify indicators to specifically guide decision-makers in their responses to climate change. A goal of the analysis is to select a manageable composite list of recommended indicators based on sustained, reliable data sources with known user communities. The selected list is also based on the development of a conceptual model that identifies components and processes critical to our understanding of the Arctic region. This list of key indicators is designed to inform the plans and priorities of multiple groups such as the U.S. Global Change Research Program (USGCRP), Interagency Arctic Research Policy Committee (IARPC), and the Arctic Council.

  20. Fate of terrigenous organic matter across the Laptev Sea from the mouth of the Lena River to the deep sea of the Arctic interior

    NARCIS (Netherlands)

    Bröder, Lisa; Tesi, Tommaso; Salvadó, Joan A.; Semiletov, Igor P.; Dudarev, Oleg V.; Gustafsson, Orjan

    2016-01-01

    Ongoing global warming in high latitudes may cause an increasing supply of permafrost-derived organic carbon through both river discharge and coastal erosion to the Arctic shelves. Mobilized permafrost carbon can be either buried in sediments, transported to the deep sea or degraded to CO2 and

  1. Implied and realized volatility in the cross-section of equity options

    DEFF Research Database (Denmark)

    Ammann, Manuel; Skovmand, David; Verhofen, Michael

    2009-01-01

    Using a complete sample of US equity options, we analyze patterns of implied volatility in the cross-section of equity options with respect to stock characteristics. We find that high-beta stocks, small stocks, stocks with a low-market-to-book ratio, and non-momentum stocks trade at higher implied...

  2. 76 FR 55904 - Michael J. Donahue; Notice of Termination of Exemption By Implied Surrender and Soliciting...

    Science.gov (United States)

    2011-09-09

    .... Donahue; Notice of Termination of Exemption By Implied Surrender and Soliciting Comments, Protests, and... Commission: a. Type of Proceeding: Termination of exemption by implied surrender. b. Project No.: 6649-008. c... Commission reserves the right to revoke an exemption if any term or condition of the exemption is violated...

  3. 76 FR 58264 - Michael J. Donahue; Notice of Termination of Exemption by Implied Surrender and Soliciting...

    Science.gov (United States)

    2011-09-20

    .... Donahue; Notice of Termination of Exemption by Implied Surrender and Soliciting Comments, Protests, and... Commission: a. Type of Proceeding: Termination of exemption by implied surrender. b. Project No.: 6649-008. c... Commission reserves the right to revoke an exemption if any term or condition of the exemption is violated...

  4. 77 FR 2057 - Aquamac Corporation; Notice of Termination of License by Implied Surrender and Soliciting...

    Science.gov (United States)

    2012-01-13

    ... Corporation; Notice of Termination of License by Implied Surrender and Soliciting Comments and Motions To.... Type of Proceeding: Termination of License by Implied Surrender. b. Project No.: 2927-006. c. Date... authorized, the licensee is in violation of the terms and conditions of the license. l. This notice is...

  5. 77 FR 73653 - Milburnie Hydro Inc.; Notice of Termination of Exemption by Implied Surrender and Soliciting...

    Science.gov (United States)

    2012-12-11

    ... Inc.; Notice of Termination of Exemption by Implied Surrender and Soliciting Comments, Protests, and... Commission: a. Type of Proceeding: Termination of exemption by implied surrender. b. Project No.: 7910-006. c... Commission reserves the right to revoke an exemption if any term or condition of the exemption is violated...

  6. 76 FR 55903 - Missisquoi River Technologies; Notice of Termination of Exemption By Implied Surrender and...

    Science.gov (United States)

    2011-09-09

    ... Technologies; Notice of Termination of Exemption By Implied Surrender and Soliciting Comments, Protests, and... Commission: a. Type of Proceeding: Termination of exemption by implied surrender. b. Project No.: 10172-038..., among other things, that the Commission reserves the right to revoke an exemption if any term or...

  7. 76 FR 7840 - American Hydro Power Company; Notice of Termination of Exemption by Implied Surrender and...

    Science.gov (United States)

    2011-02-11

    ... Power Company; Notice of Termination of Exemption by Implied Surrender and Soliciting Comments, Protests... the Commission: a. Type of Proceeding: Termination of exemption by implied surrender. b. Project No... if any term or condition of the exemption is violated. The project has not operated since 2004, and...

  8. Advising Students or Practicing Law: The Formation of Implied Attorney-Client Relationships with Students

    Science.gov (United States)

    Sheridan, Patricia M.

    2014-01-01

    An attorney-client relationship is traditionally created when both parties formally enter into an express agreement regarding the terms of representation and the payment of fees. There are certain circumstances, however, where the attorney-client relationship can be implied from the parties' conduct. An implied attorney-client relationship may…

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

    Science.gov (United States)

    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

  10. Arctic pipeline planning design, construction, and equipment

    CERN Document Server

    Singh, Ramesh

    2013-01-01

    Utilize the most recent developments to combat challenges such as ice mechanics. The perfect companion for engineers wishing to learn state-of-the-art methods or further develop their knowledge of best practice techniques, Arctic Pipeline Planning provides a working knowledge of the technology and techniques for laying pipelines in the coldest regions of the world. Arctic Pipeline Planning provides must-have elements that can be utilized through all phases of arctic pipeline planning and construction. This includes information on how to: Solve challenges in designing arctic pipelines Protect pipelines from everyday threats such as ice gouging and permafrost Maintain safety and communication for construction workers while supporting typical codes and standards Covers such issues as land survey, trenching or above ground, environmental impact of construction Provides on-site problem-solving techniques utilized through all phases of arctic pipeline planning and construction Is packed with easy-to-read and under...

  11. Ecosystem-atmosphere interactions in the Arctic

    DEFF Research Database (Denmark)

    López-Blanco, Efrén

    The terrestrial CO2 exchange in the Arctic plays an important role in the global carbon (C) cycle. The Arctic ecosystems, containing a large amount of organic carbon (C), are experiencing on-going warming in recent decades, which is affecting the C cycling and the feedback interactions between its...... of measurement sites, particularly covering full annual cycles, but also the frequent gaps in data affected by extreme conditions and remoteness. Combining ecosystem models and field observations we are able to study the underlying processes of Arctic CO2 exchange in changing environments. The overall aim...... of the research is to use data-model approaches to analyse the patterns of C exchange and their links to biological processes in Arctic ecosystems, studied in detail both from a measurement and a modelling perspective, but also from a local to a pan-arctic scale. In Paper I we found a compensatory response...

  12. CHARACTERISTICS OF HYDROCARBON EXPLOITATION IN ARCTIC CIRCLE

    Directory of Open Access Journals (Sweden)

    Vanja Lež

    2013-12-01

    Full Text Available The existence of large quantities of hydrocarbons is supposed within the Arctic Circle. Assumed quantities are 25% of the total undiscovered hydrocarbon reserves on Earth, mostly natural gas. Over 500 major and minor gas accumulations within the Arctic Circle were discovered so far, but apart from Snøhvit gas field, there is no commercial exploitation of natural gas from these fields. Arctic gas projects are complicated, technically hard to accomplish, and pose a great threat to the return of investment, safety of people and equipment and for the ecosystem. Russia is a country that is closest to the realization of the Arctic gas projects that are based on the giant gas fields. The most extreme weather conditions in the seas around Greenland are the reason why this Arctic region is the least explored and furthest from the realization of any gas project (the paper is published in Croatian .

  13. Tipping elements in the Arctic marine ecosystem.

    Science.gov (United States)

    Duarte, Carlos M; Agustí, Susana; Wassmann, Paul; Arrieta, Jesús M; Alcaraz, Miquel; Coello, Alexandra; Marbà, Núria; Hendriks, Iris E; Holding, Johnna; García-Zarandona, Iñigo; Kritzberg, Emma; Vaqué, Dolors

    2012-02-01

    The Arctic marine ecosystem contains multiple elements that present alternative states. The most obvious of which is an Arctic Ocean largely covered by an ice sheet in summer versus one largely devoid of such cover. Ecosystems under pressure typically shift between such alternative states in an abrupt, rather than smooth manner, with the level of forcing required for shifting this status termed threshold or tipping point. Loss of Arctic ice due to anthropogenic climate change is accelerating, with the extent of Arctic sea ice displaying increased variance at present, a leading indicator of the proximity of a possible tipping point. Reduced ice extent is expected, in turn, to trigger a number of additional tipping elements, physical, chemical, and biological, in motion, with potentially large impacts on the Arctic marine ecosystem.

  14. Fractional Black–Scholes option pricing, volatility calibration and implied Hurst exponents in South African context

    Directory of Open Access Journals (Sweden)

    Emlyn Flint

    2017-03-01

    Full Text Available Background: Contingent claims on underlying assets are typically priced under a framework that assumes, inter alia, that the log returns of the underlying asset are normally distributed. However, many researchers have shown that this assumption is violated in practice. Such violations include the statistical properties of heavy tails, volatility clustering, leptokurtosis and long memory. This paper considers the pricing of contingent claims when the underlying is assumed to display long memory, an issue that has heretofore not received much attention. Aim: We address several theoretical and practical issues in option pricing and implied volatility calibration in a fractional Black–Scholes market. We introduce a novel eight-parameter fractional Black–Scholes-inspired (FBSI model for the implied volatility surface, and consider in depth the issue of calibration. One of the main benefits of such a model is that it allows one to decompose implied volatility into an independent long-memory component – captured by an implied Hurst exponent – and a conditional implied volatility component. Such a decomposition has useful applications in the areas of derivatives trading, risk management, delta hedging and dynamic asset allocation. Setting: The proposed FBSI volatility model is calibrated to South African equity index options data as well as South African Rand/American Dollar currency options data. However, given the focus on the theoretical development of the model, the results in this paper are applicable across all financial markets. Methods: The FBSI model essentially combines a deterministic function form of the 1-year implied volatility skew with a separate deterministic function for the implied Hurst exponent, thus allowing one to model both observed implied volatility surfaces as well as decompose them into independent volatility and long-memory components respectively. Calibration of the model makes use of a quasi-explicit weighted

  15. Establishing Shared Knowledge about Globalization in Asia and the Arctic

    DEFF Research Database (Denmark)

    Bertelsen, Rasmus Gjedssø; Graczyk, Piotr

    2016-01-01

    We discuss the role of knowledge in relations between Arctic communities and Asia (the Arctic Council observer states: China, India, Japan, Singapore, South Korea). We argue that mutual and shared knowledge between Arctic communities and Asia is necessary for local benefits and comprehensively su...... sustainable development for Arctic communities under globalization....

  16. Advancing NOAA NWS Arctic Program Development

    Science.gov (United States)

    Timofeyeva-Livezey, M. M.; Horsfall, F. M. C.; Meyers, J. C.; Churma, M.; Thoman, R.

    2016-12-01

    Environmental changes in the Arctic require changes in the way the National Oceanic and Atmospheric Administration (NOAA) delivers hydrological and meteorological information to prepare the region's societies and indigenous population for emerging challenges. These challenges include changing weather patterns, changes in the timing and extent of sea ice, accelerated soil erosion due to permafrost decline, increasing coastal vulnerably, and changes in the traditional food supply. The decline in Arctic sea ice is opening new opportunities for exploitation of natural resources, commerce, tourism, and military interest. These societal challenges and economic opportunities call for a NOAA integrated approach for delivery of environmental information including climate, water, and weather data, forecasts, and warnings. Presently the NOAA Arctic Task Force provides leadership in programmatic coordination across NOAA line offices. National Weather Service (NWS) Alaska Region and the National Centers for Environmental Prediction (NCEP) provide the foundational operational hydro-meteorological products and services in the Arctic. Starting in 2016, NOAA's NWS will work toward improving its role in programmatic coordination and development through assembling an NWS Arctic Task Team. The team will foster ties in the Arctic between the 11 NWS national service programs in climate, water, and weather information, as well as between Arctic programs in NWS and other NOAA line offices and external partners. One of the team outcomes is improving decision support tools for the Arctic. The Local Climate Analysis Tool (LCAT) currently has more than 1100 registered users, including NOAA staff and technical partners. The tool has been available online since 2013 (http://nws.weather.gov/lcat/ ). The tool links trusted, recommended NOAA data and analytical capabilities to assess impacts of climate variability and climate change at local levels. A new capability currently being developed will

  17. Holocene Temperature Reconstructions from Arctic Lakes based on Alkenone Paleothermometry and Non-Destructive Scanning Techniques

    Science.gov (United States)

    D'Andrea, W. J.; Balascio, N. L.; Bradley, R. S.; Bakke, J.; Gjerde, M.; Kaufman, D. S.; Briner, J. P.; von Gunten, L.

    2014-12-01

    Generating continuous, accurate and quantitative Holocene temperature estimates from the Arctic is an ongoing challenge. In many Arctic regions, tree ring-based approaches cannot be used and lake sediments provide the most valuable repositories for extracting paleotemperature information. Advances in lacustrine alkenone paleothermometry now allow for quantitative reconstruction of lake-water temperature based on the UK37 values of sedimentary alkenones. In addition, a recent study demonstrated the efficacy of non-destructive scanning reflectance spectroscopy in the visible range (VIS-RS) for high-resolution quantitative temperature reconstruction from arctic lake sediments1. In this presentation, I will report a new UK37-based temperature reconstruction and a scanning VIS-RS record (using the RABD660;670 index as a measure of sedimentary chlorin content) from Kulusuk Lake in southeastern Greenland (65.6°N, 37.1°W). The UK37 record reveals a ~3°C increase in summer lake water temperatures between ~10ka and ~7ka followed by sustained warmth until ~4ka and a gradual (~3°C) cooling until ~400 yr BP. The strong correlation between UK37 and RABD660;670 measured in the same sediment core provides further evidence that in arctic lakes where temperature regulates primary productivity, and thereby sedimentary chlorin content, these proxies can be combined to develop high-resolution quantitative temperature records. The Holocene temperature history of Kulusuk Lake determined using this approach corresponds to changes in the size of the glaciers adjacent to the lake, as inferred from sediment minerogenic properties measured with scanning XRF. Glaciers retreated during early Holocene warming, likely disappeared during the period of mid-Holocene warmth, and advanced after 4ka. I will also discuss new UK37 and RABD660;670 reconstructions from northwestern Svalbard and the central Brooks Range of Alaska within the framework of published regional temperature reconstructions and

  18. Pleniglacial sedimentation process reconstruction on laminated lacustrine sediments from lava-dammed Paleolake Alf, West Eifel Volcanic Field (Germany)

    Science.gov (United States)

    Eichhorn, Luise; Pirrung, Michael; Zolitschka, Bernd; Büchel, Georg

    2017-09-01

    Differentiating between regularly seasonal, irregular and event-based clastic sedimentation is difficult if sedimentation structures resemble and dating methods are imprecise. In this study - clastic light and dark laminae from lava-dammed Paleolake Alf in the Late Pleistocene in the Quaternary West Eifel Volcanic Field are analyzed to clarify how they formed and if they are of annual origin and comparable to assumed periglacial varves from neighboring Lake Holzmaar. Therefore, a multiproxy approach is applied combining sediment thin section analysis which focuses on composition and structure with 14C dates. The results are compared to recently-formed annually-laminated clastic sediments of, e.g., the High Canadian Arctic. Observed sedimentation structures reveal sediment delivery by over- and interflows and deposition from suspension forming two characteristic microfacies: Type I graded laminae and Type II laminae with graded sublayers. Additionally, erosional bases and event deposits indicate episodic underflows. Thus, lamination is potentially seasonal but is significantly veiled by extreme runoff causing erosion and resuspension processes or a mixed water body preventing sediment delivery into the lake basin. However, sedimentation processes between watershed and lake could be reconstructed by comparing recent and paleosediment structures.

  19. Arctic potential - Could more structured view improve the understanding of Arctic business opportunities?

    Science.gov (United States)

    Hintsala, Henna; Niemelä, Sami; Tervonen, Pekka

    2016-09-01

    The increasing interest towards the Arctic has been witnessed during the past decades. However, the commonly shared definitions of the Arctic key concepts have not yet penetrated national and international arenas for political and economic decision making. The lack of jointly defined framework has made different analyses related to the Arctic quite limited considering the magnitude of economic potential embedded in Arctic. This paper is built on the key findings of two separate, yet connected projects carried out in the Oulu region, Finland. In this paper's approach, the Arctic context has been defined as a composition of three overlapping layers. The first layer is the phenomenological approach to define the Arctic region. The second layer is the strategy-level analysis to define different Arctic paths as well as a national level description of a roadmap to Arctic specialization. The third layer is the operationalization of the first two layers to define the Arctic business context and business opportunities. The studied case from Oulu region indicates that alternative futures for the Arctic competences and business activities are in resemblance with only two of the four identified strategic pathways. Introduction of other pathways to regional level actors as credible and attractive options would require additional, systematic efforts.

  20. The Arctic zone: possibilities and risks of development

    Science.gov (United States)

    Sentsov, A.; Bolsunovskaya, Y.; Melnikovich, E.

    2016-09-01

    The authors analyze the Arctic region innovative possibilities from the perspective of political ideology and strategy. The Arctic region with its natural resources and high economic potential attracts many companies and it has become an important area of transnational development. At present, the Arctic region development is of great importance in terms of natural resource management and political system development. However, the most important development issue in the Arctic is a great risk of different countries’ competing interests in economic, political, and legal context. These are challenges for international partnership creating in the Arctic zone, Russian future model developing for the Arctic, and recognition of the Arctic as an important resource for the Russians. The Russian economic, military, and political expansion in the Arctic region has the potential to strengthen the national positions. The authors present interesting options for minimizing and eliminating political risks during the Arctic territories development and define an effective future planning model for the Russian Arctic.

  1. Chemistry of marine sediments

    International Nuclear Information System (INIS)

    Yen, T.F.

    1977-01-01

    Some topics considered are as follows: characterization of sediments in the vicinity of offshore petroleum production; thermal alteration experiments on organic matter in recent marine sediments as a model for petroleum genesis; composition of polluted bottom sediments in Great Lakes harbors; distribution of heavy metals in sediment fractions; recent deposition of lead off the coast of southern California; release of trace constituents from sediments resuspended during dredging operations; and migration of chemical constituents in sediment-seawater interfaces

  2. Constraining Lipid Biomarker Paleoclimate Proxies in a Small Arctic Watershed

    Science.gov (United States)

    Dion-Kirschner, H.; McFarlin, J. M.; Axford, Y.; Osburn, M. R.

    2017-12-01

    Arctic amplification of climate change renders high-latitude environments unusually sensitive to changes in climatic conditions (Serreze and Barry, 2011). Lipid biomarkers, and their hydrogen and carbon isotopic compositions, can yield valuable paleoclimatic and paleoecological information. However, many variables affect the production and preservation of lipids and their constituent isotopes, including precipitation, plant growth conditions, biosynthesis mechanisms, and sediment depositional processes (Sachse et al., 2012). These variables are particularly poorly constrained for high-latitude environments, where trees are sparse or not present, and plants grow under continuous summer light and cool temperatures during a short growing season. Here we present a source-to-sink study of a single watershed from the Kangerlussuaq region of southwest Greenland. Our analytes from in and around `Little Sugarloaf Lake' (LSL) include terrestrial and aquatic plants, plankton, modern lake water, surface sediments, and a sediment core. This diverse sample set allows us to fulfill three goals: 1) We evaluate the production of lipids and isotopic signatures in the modern watershed in comparison to modern climate. Our data exhibit genus-level trends in leaf wax production and isotopic composition, and help clarify the difference between terrestrial and aquatic signals. 2) We evaluate the surface sediment of LSL to determine how lipid biomarkers from the watershed are incorporated into sediments. We constrain the relative contributions of terrestrial plants, aquatic plants, and other aquatic organisms to the sediment in this watershed. 3) We apply this modern source-to-sink calibration to the analysis of a 65 cm sediment core record. Our core is organic-rich, and relatively high deposition rates allow us to reconstruct paleoenvironmental changes with high resolution. Our work will help determine the veracity of these common paleoclimate proxies, specifically for research in

  3. Arctic polynya and glacier interactions

    Science.gov (United States)

    Edwards, Laura

    2013-04-01

    Major uncertainties surround future estimates of sea level rise attributable to mass loss from the polar ice sheets and ice caps. Understanding changes across the Arctic is vital as major potential contributors to sea level, the Greenland Ice Sheet and the ice caps and glaciers of the Canadian Arctic archipelago, have experienced dramatic changes in recent times. Most ice mass loss is currently focused at a relatively small number of glacier catchments where ice acceleration, thinning and calving occurs at ocean margins. Research suggests that these tidewater glaciers accelerate and iceberg calving rates increase when warming ocean currents increase melt on the underside of floating glacier ice and when adjacent sea ice is removed causing a reduction in 'buttressing' back stress. Thus localised changes in ocean temperatures and in sea ice (extent and thickness) adjacent to major glacial catchments can impact hugely on the dynamics of, and hence mass lost from, terrestrial ice sheets and ice caps. Polynyas are areas of open water within sea ice which remain unfrozen for much of the year. They vary significantly in size (~3 km2 to > ~50,000 km2 in the Arctic), recurrence rates and duration. Despite their relatively small size, polynyas play a vital role in the heat balance of the polar oceans and strongly impact regional oceanography. Where polynyas develop adjacent to tidewater glaciers their influence on ocean circulation and water temperatures may play a major part in controlling subsurface ice melt rates by impacting on the water masses reaching the calving front. Areas of open water also play a significant role in controlling the potential of the atmosphere to carry moisture, as well as allowing heat exchange between the atmosphere and ocean, and so can influence accumulation on (and hence thickness of) glaciers and ice caps. Polynya presence and size also has implications for sea ice extent and therefore potentially the buttressing effect on neighbouring

  4. Arctic Visiting Speakers Series (AVS)

    Science.gov (United States)

    Fox, S. E.; Griswold, J.

    2011-12-01

    The Arctic Visiting Speakers (AVS) Series funds researchers and other arctic experts to travel and share their knowledge in communities where they might not otherwise connect. Speakers cover a wide range of arctic research topics and can address a variety of audiences including K-12 students, graduate and undergraduate students, and the general public. Host applications are accepted on an on-going basis, depending on funding availability. Applications need to be submitted at least 1 month prior to the expected tour dates. Interested hosts can choose speakers from an online Speakers Bureau or invite a speaker of their choice. Preference is given to individuals and organizations to host speakers that reach a broad audience and the general public. AVS tours are encouraged to span several days, allowing ample time for interactions with faculty, students, local media, and community members. Applications for both domestic and international visits will be considered. Applications for international visits should involve participation of more than one host organization and must include either a US-based speaker or a US-based organization. This is a small but important program that educates the public about Arctic issues. There have been 27 tours since 2007 that have impacted communities across the globe including: Gatineau, Quebec Canada; St. Petersburg, Russia; Piscataway, New Jersey; Cordova, Alaska; Nuuk, Greenland; Elizabethtown, Pennsylvania; Oslo, Norway; Inari, Finland; Borgarnes, Iceland; San Francisco, California and Wolcott, Vermont to name a few. Tours have included lectures to K-12 schools, college and university students, tribal organizations, Boy Scout troops, science center and museum patrons, and the general public. There are approximately 300 attendees enjoying each AVS tour, roughly 4100 people have been reached since 2007. The expectations for each tour are extremely manageable. Hosts must submit a schedule of events and a tour summary to be posted online

  5. The Far East taiga forest: unrecognized inhospitable terrain for migrating Arctic-nesting waterbirds?

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2018-02-01

    Full Text Available The degree of inhospitable terrain encountered by migrating birds can dramatically affect migration strategies and their evolution as well as influence the way we develop our contemporary flyway conservation responses to protect them. We used telemetry data from 44 tagged individuals of four large-bodied, Arctic breeding waterbird species (two geese, a swan and one crane species to show for the first time that these birds fly non-stop over the Far East taiga forest, despite their differing ecologies and migration routes. This implies a lack of suitable taiga refuelling habitats for these long-distance migrants. These results underline the extreme importance of northeast China spring staging habitats and of Arctic areas prior to departure in autumn to enable birds to clear this inhospitable biome, confirming the need for adequate site safeguard to protect these populations throughout their annual cycle.

  6. Nutrient availability limits biological production in Arctic sea ice melt ponds

    DEFF Research Database (Denmark)

    Sørensen, Heidi Louise; Thamdrup, Bo; Jeppesen, Erik

    2017-01-01

    nutrient limitation in melt ponds. We also document that the addition of nutrients, although at relative high concentrations, can stimulate biological productivity at several trophic levels. Given the projected increase in first-year ice, increased melt pond coverage during the Arctic spring and potential......Every spring and summer melt ponds form at the surface of polar sea ice and become habitats where biological production may take place. Previous studies report a large variability in the productivity, but the causes are unknown. We investigated if nutrients limit the productivity in these first...... additional nutrient supply from, e.g. terrestrial sources imply that biological activity of melt ponds may become increasingly important for the sympagic carbon cycling in the future Arctic....

  7. Circulation and Respiration in Ice-covered Alaskan Arctic Lakes

    Science.gov (United States)

    MacIntyre, S.; Cortés, A.

    2016-12-01

    Arctic lakes are ice-covered 9 months of the year. For some of this time, the sediments heat the overlying water, and respiration in the sediments increases specific conductivity, depletes oxygen, and produces greenhouse gases (GHG). Whether anoxia forms and whether the greenhouse gases are sequestered at depth depends on processes inducing circulation and upward fluxes. Similarly, whether the GHG are released at ice off depends on the extent of vertical mixing at that time. Using time series meteorological data and biogeochemical arrays with temperature, specific conductivity, and optical oxygen sensors in 5 lakes ranging from 1 to 150 ha, we illustrate the connections between meteorological forcing and within lake processes including gravity currents resulting from increased density just above the sediment water interface and internal waves including those induced by winds acting on the surface of the ice and at ice off. CO2 production was well predicted by the initial rate of oxygen drawdown near the bottom at ice on and that the upward density flux depended on lake size, with values initially high in all lakes but near molecular in lakes of a few hectares in size by mid-winter. Both CO2 production and within lake vertical fluxes were independent of the rate of cooling in fall and subsequent within lake temperatures under the ice. Anoxia formed near the sediments in all 5 lakes with the concentration of CH4 dependent, in part, on lake size and depth. Twenty to fifty percent of the greenhouse gases produced under the ice remained in the lakes by the time thermal stratification was established in summer despite considerable internal wave induced mixing at the time of ice off. These observations and analysis lay a framework for understanding the links between within lake hydrodynamics, within year variability, and the fraction of greenhouse gases produced over the winter which evade at ice off.

  8. Coordinating for Arctic Conservation: Implementing Integrated Arctic Biodiversity Monitoring, Data Management and Reporting

    Science.gov (United States)

    Gill, M.; Svoboda, M.

    2012-12-01

    Arctic ecosystems and the biodiversity they support are experiencing growing pressure from various stressors (e.g. development, climate change, contaminants, etc.) while established research and monitoring programs remain largely uncoordinated, lacking the ability to effectively monitor, understand and report on biodiversity trends at the circumpolar scale. The maintenance of healthy arctic ecosystems is a global imperative as the Arctic plays a critical role in the Earth's physical, chemical and biological balance. A coordinated and comprehensive effort for monitoring arctic ecosystems is needed to facilitate effective and timely conservation and adaptation actions. The Arctic's size and complexity represents a significant challenge towards detecting and attributing important biodiversity trends. This demands a scaled, pan-arctic, ecosystem-based approach that not only identifies trends in biodiversity, but also identifies underlying causes. It is critical that this information be made available to generate effective strategies for adapting to changes now taking place in the Arctic—a process that ultimately depends on rigorous, integrated, and efficient monitoring programs that have the power to detect change within a "management" time frame. To meet these challenges and in response to the Arctic Climate Impact Assessment's recommendation to expand and enhance arctic biodiversity monitoring, the Conservation of Arctic Flora and Fauna (CAFF) Working Group of the Arctic Council launched the Circumpolar Biodiversity Monitoring Program (CBMP). The CBMP is led by Environment Canada on behalf of Canada and the Arctic Council. The CBMP is working with over 60 global partners to expand, integrate and enhance existing arctic biodiversity research and monitoring efforts to facilitate more rapid detection, communication and response to significant trends and pressures. Towards this end, the CBMP has established three Expert Monitoring Groups representing major Arctic

  9. Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

    Science.gov (United States)

    Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

    2010-01-01

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

  10. The implied volatility of U.S. interest rates: evidence from callable U. S. Treasuries

    OpenAIRE

    Robert R. Bliss; Ehud I. Ronn

    1995-01-01

    The prices for callable U.S. Treasury securities provide the sole source of evidence concerning the implied volatility of interest rates over the extended 1926-1994 period. This paper uses the prices of callable as well as non-callable Treasury instruments to estimate implied interest rate volatilities for the past sixty years, and, for the more recent 1989-1994 period, the cross-sectional term structures of implied interest rate volatility. We utilize these estimates to perform cross-section...

  11. 1992 Progress report on sediment-related aspects of northern hydrocarbon development

    Energy Technology Data Exchange (ETDEWEB)

    1993-01-01

    The Mackenzie Delta is ecologically important for its outflow of warm, sediment-laden water to the Arctic Ocean. Lack of knowledge and clear understanding of delta processes raise serious concerns over potential impacts from development of local hydrocarbon resources on Delta ecosystems. The Northern Oil and Gas Program is sponsoring research on Mackenzie Delta hydrology and hydraulics, sediment flux, contaminant levels, and other issues relevant to impacts of hydrocarbon development. A compendium of five reports on the sediment-related aspects of this research is presented. The topics of the reports are: suspended sediment sampling; sedimentation measurement; channel stability; hydraulic and morphologic surveys; and sediment station data. A separate abstract has been prepared for each of the five reports.

  12. Arctic pollution: How much is too much

    Energy Technology Data Exchange (ETDEWEB)

    An overview is presented of the problems of pollution in the Arctic. Pollution from lower latitudes is carried into the Arctic by atmospheric circulation and ocean currents. Contamination of snow, waters and organisms with imported pollutants has appeared in the past few decades and appears to be increasing. Arctic ecosystems show indications of being much more susceptible to biological damage at low levels of pollutants than higher-energy ecosystems in temperate latitudes, and many Arctic organisms become accumulators and concentrators of organic pollutants and toxic metals. Arctic haze is 20 to 40 times as high in winter as in summer and has been found to consist of particles of largely industrial origin, mostly soot, hydrocarbons and sulphates. Dramatic declines in stratospheric ozone have been apparent over Antarctica, and a similar but less intense depletion is appearing over the Arctic. Toxic compounds, particularly organochlorines and some heavy metals, have been found in worrying amounts in snow, water and organisms in Arctic North America, Greenland and Svalbard. Radioactive contamination was widespread during atmospheric testing of nuclear weapons during the 1960s and 1970s, and the comparatively small amount of radiation released by the Chernobyl accident had greatest effect in northern Scandinavia. 4 figs.

  13. THE ARCTIC: A DIALOGUE FOR DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Yury Mazurov

    2010-01-01

    Full Text Available In September 2010, Moscow hosted the International Arctic Forum “The Arctic—Territory of Dialogue.” The Arctic Forum focused its attention on elements of sustainable development in the Arctic region, i.e., ecology, economics, infrastructure, social services, security, and geopolitics. Many Russian experts and many well-known politicians and experts from leading research centers of the Arctic countries (Canada, Denmark, Finland, Iceland, Norway, Sweden, and USA, as well as by participants from France, Germany, Netherlands, and other countries attended the forum. Scholars and public figures from the European countries, representatives of the NATO, the Organization for Security and Cooperation in Europe and other institutions were also present at the conference. In his key-note speech the Chairman of the Board of Trustees of the Russian Geographical Society (RGS, Prime Minister of the Russian Federation, Vladimir V. Putin formulated the principles of Russian national policy in the Arctic. Russian and foreign participants supported the idea of continuing dialogue on the Arctic under the RGS’s aegis and the transformation of the Arctic Forum into a permanent platform for discussions on the most urgent issues of the region.

  14. Arctic Energy Resources: Security and Environmental Implications

    Directory of Open Access Journals (Sweden)

    Peter Johnston

    2012-08-01

    Full Text Available n recent years, there has been considerable interest in the Arctic as a source for resources, as a potential zone for commercial shipping, and as a region that might experience conflict due to its strategic importance. With regards to energy resources, some studies suggest that the region contains upwards of 13 percent of global undiscovered oil, 30 percent of undiscovered gas, and multiples more of gas hydrates. The decreasing amount and duration of Arctic ice cover suggests that extraction of these resources will be increasingly commercially viable. Arctic and non-arctic states wish to benefit from the region's resources and the potential circum-polar navigation possibilities. This has led to concerns about the environmental risks of these operations as well as the fear that competition between states for resources might result in conflict. Unresolved offshore boundaries between the Arctic states exacerbate these fears. Yet, the risk of conflict seems overstated considering the bilateral and multilateral steps undertaken by the Arctic states to resolve contentious issues. This article will examine the potential impact of Arctic energy resources on global security as well as the regional environment and examine the actions of concerned states to promote their interests in the region.

  15. Orbital-scale Central Arctic Ocean Temperature Records from Benthic Foraminiferal δ18O and Ostracode Mg/Ca Ratios

    Science.gov (United States)

    Keller, K.; Cronin, T. M.; Dwyer, G. S.; Farmer, J. R.; Poirier, R. K.; Schaller, M. F.

    2017-12-01

    Orbital-scale climate variability is often amplified in the polar region, for example in changes in seawater temperature, sea-ice cover, deep-water formation, ecosystems, heat storage and carbon cycling. Yet, the relationship between the Arctic Ocean and global climate remains poorly understood due largely to limited orbital-scale paleoclimate records, the complicated nature of sea-ice response to climate and limited abundance of deep sea biological proxies. Here we reconstruct central Arctic Ocean bottom temperatures over the last 600 kyr using ostracode Mg/Ca ratios (genus Krithe) and benthic foraminiferal oxygen isotope ratios (δ18Obf - I. teretis, O. tener, P. bulloides, C. reniforme, C. wuellerstorfi) in six sediment cores recovered from the Mendeleev and Northwind Ridges (700- 2726 m water depth). We examined glacial-interglacial cycles in Arctic seawater temperatures and Arctic δ18Obf chronostratigraphy to reconcile effects of changing bottom water temperature, ice volume and regional hydrography on δ18Obf records. Results show lower ( 10-12 mmol/mol) interglacial and higher ( 16-23 mmol/mol) glacial Mg/Ca ratios, signifying intermediate depth ocean warming during glacials of up to 2 ºC. These temperature maxima are likely related to a deepening of the halocline and the corresponding deeper influence of warm Atlantic water. Glacial-interglacial δ18Obf ranges are smaller in the Arctic ( 0.8-1‰ VPDB) than in the global ocean ( 1.8 ‰). However, when the distinct glacial-interglacial temperature histories of the Arctic (glacial warming) and global ocean (glacial cooling) are accounted for, both Arctic and global ocean seawater δ18O values (δ18Osw) exhibit similar 1.2-1.3 ‰ glacial-interglacial ranges. Thus, Arctic δ18Obf confirms glacial Arctic warming inferred from ostracode Mg/Ca. This study will discuss the strengths and limitations of applying paired Mg/Ca and oxygen isotope proxies in reconstructing more robust paleoceanographic changes in the

  16. Facility engineering for Arctic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, D.M.; McClusky, K.R.; Shirley, R.; Spitzenberger, R. [Mustang Engineering Inc., Houston, TX (United States)

    2001-07-01

    The Northstar Development Project is located on Seal Island in the Beaufort Sea, north of Prudhoe Bay. The design and engineering of the facilities for the Northstar Development Project was fraught with challenges. Mustang Engineering Incorporated was involved in the design and engineering of the pipe rack, pump house, process and compressor modules. All the characteristics of an offshore facility are present, even though the project is land-based on a man-made island. A number of the strategies developed for offshore platforms of the Gulf of Mexico were adapted to the fabrication, logistics and installation of the modules. To reduce yard fabrication time, a modularized design concept was adopted. Cost savings and onsite fabrication efficiencies were realized through open communication with the operator, early discussions with vendors, regulatory agencies, and local fabrication and installation contractors. Some improvisation and deviations were required to meet the stringent requirements for operation under Arctic conditions. The lessons learned on this project will be of use in future Arctic projects. 1 tab., 6 figs.

  17. Survival strategies in arctic ungulates

    Directory of Open Access Journals (Sweden)

    N. J. C. Tyler

    1990-09-01

    Full Text Available Arctic ungulates usually neither freeze nor starve to death despite the rigours of winter. Physiological adaptations enable them to survive and reproduce despite long periods of intense cold and potential undernutrition. Heat conservation is achieved by excellent insulation combined with nasal heat exchange. Seasonal variation in fasting metabolic rate has been reported in several temperate and sub-arctic species of ungulates and seems to occur in muskoxen. Surprisingly, there is no evidence for this in reindeer. Both reindeer and caribou normally maintain low levels of locomotor activity in winter. Light foot loads are important for reducing energy expenditure while walking over snow. The significance and control of selective cooling of the brain during hard exercise (e.g. escape from predators is discussed. Like other cervids, reindeer and caribou display a pronounced seasonal cycle of appetite and growth which seems to have an intrinsic basis. This has two consequences. First, the animals evidently survive perfectly well despite enduring negative energy balance for long periods. Second, loss of weight in winter is not necessarily evidence of undernutrition. The main role of fat reserves, especially in males, may be to enhance reproductive success. The principal role of fat reserves in winter appears to be to provide a supplement to, rather than a substitute for, poor quality winter forage. Fat also provides an insurance against death during periods of acute starvation.

  18. Differentiating TOC sources, preservation, and potential methane emissions in sub-Arctic lakes in Sweden

    Science.gov (United States)

    Johnson, J. E.; Varner, R. K.; Wik, M.; Chanton, J.; Crill, P. M.

    2015-12-01

    Organic carbon-rich sediments from high latitude, shallow lakes and ponds are significant sources of methane throughout the Arctic. The origin and evolution of these lakes and ponds, however, is often not the same. Several lake types have been identified based on (1) hydrological conditions (melt-water fed, rain water fed, groundwater influenced, evaporation dominated, drained) (2) permafrost condition (thermokarst), and (3) time of origin (glacial or post-glacial). Given sufficient time (100's to 1000's years) many of these lake types may morph into others. In sub-Arctic Sweden, near Abisko and within the zone of discontinuous permafrost, the elongate glacial lake Torneträsk is fed by several streams draining the surrounding highlands. Lake Tornetrask is one of several NW-SE trending glacial lakes common in the landscape throughout northern and western Sweden. Between and alongside these glacial lakes, several small (ponds exist in low-lying mires. Sediment cores from the lakes in the Stordalen Mire are characterized by high total organic carbon (TOC) content (10-50 wt. %) in the uppermost ~50 cm and commonly underlain by glaciofluvial derived sediments with lower TOC (emissions from several of these lakes has also been measured and is driven by heat input. Coincident young ages of carbon in the sediments and in methane indicate in situ production. A published record from Lake Torneträsk shows sediments there contain significantly less TOC (1-2.5 wt. %) that is derived primarily from old, terrestrial organic carbon delivered via rivers to the lake. Although the larger and deeper glacial lakes currently occupy much of the landscape it is becoming clear that as the Arctic warms TOC preservation and methane production in the smaller lakes and ponds play a more significant, immediate role in emission of methane to the atmosphere. With continued warming in the Arctic, terrestrial TOC will be relinquished from highland watersheds to glacial lakes, but the methane

  19. Deposition of plutonium isotopes and Cs-137 in sediments of the Ob delta from the beginning of the nuclear age

    International Nuclear Information System (INIS)

    Panteleyev, G.P.; Livingston, H.D.; Sayles, F.L.; Medkova, O.N.

    1995-01-01

    As an approach to an assessment of the transport of artificial radionuclides through the Ob river system towards the arctic Ocean, results are presented from the analyses of a series of sediment cores collected in the Ob delta and estuary in 1994. These cores, collected in areas of sediment accumulation, contain the depositional history at the Ob mouth of substances associated with sediment particles from the whole river system watershed. Several approaches to dating these sediments permitted the development of a chronology for the deposition of plutonium isotopes and Cs-137, following their first introduction to the environment a half century ago. Some preliminary results for I-129 are also presented. 6 figs

  20. Butyltins in the sediments of Kochi and Mumbai harbours, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Garg, A.; Harji, R.; Jadhav, S.; Sawant, S.S.; Krishnamurthy, V.; Anil, A.C.

    positive relationships with organic carbon and lipid, implying that both lipophilic and ionic interactions were probably involved in controlling the abundance of TBT at these sediments. The observed levels of butyltin compounds are much higher than those...

  1. Biological Environmental Arctic Project (BEAP) Preliminary Data (Arctic West Summer 1986 Cruise).

    Science.gov (United States)

    1986-11-01

    predictive model of bioluminescence in near-surface arctic waters . Data were collected during Arctic West Summer 1986 from USCG POLAR STAR (WAGB 10). . %. J...2 20ODISTRIBUTION AVAILABILIT "Y OF ABSTRACT 21 ABSTRACT SECURITY CLASSIFICATION C]UNCLASSIFIED UNLIMITED SAME AS RPT C] DTIC USERS UNCLASSIFIED David...correlates for a predictive model of bioluminescence in near-surface arctic waters . - In previous years, these measurements were conducted from the USCG

  2. Analysing Discursive Practices in Legal Research : How a Single Remark Implies a Paradigm

    NARCIS (Netherlands)

    van den Hoven, P.J.

    2017-01-01

    Different linguistic theories of meaning (semantic theories) imply different methods to discuss meaning. Discussing meaning is what legal practitioners frequently do to decide legal issues and, subsequently, legal scholars analyse in their studies these discursive practices of parties, judges and

  3. Food and disturbance effects on Arctic benthic biomass and production size spectra

    Science.gov (United States)

    Górska, Barbara; Włodarska-Kowalczuk, Maria

    2017-03-01

    Body size is a fundamental biological unit that is closely coupled to key ecological properties and processes. At the community level, changes in size distributions may influence energy transfer pathways in benthic food webs and ecosystem carbon cycling; nevertheless they remain poorly explored in benthic systems, particularly in the polar regions. Here, we present the first assessment of the patterns of benthic biomass size spectra in Arctic coastal sediments and explore the effects of glacial disturbance and food availability on the partitioning of biomass and secondary productivity among size-defined components of benthic communities. The samples were collected in two Arctic fjords off west Spitsbergen (76 and 79°N), at 6 stations that represent three regimes of varying food availability (indicated by chlorophyll a concentration in the sediments) and glacial sedimentation disturbance intensity (indicated by sediment accumulation rates). The organisms were measured using image analysis to assess the biovolume, biomass and the annual production of each individual. The shape of benthic biomass size spectra at most stations was bimodal, with the location of a trough and peaks similar to those previously reported in lower latitudes. In undisturbed sediments macrofauna comprised 89% of the total benthic biomass and 56% of the total production. The lower availability of food resources seemed to suppress the biomass and secondary production across the whole size spectra (a 6-fold decrease in biomass and a 4-fold decrease in production in total) rather than reshape the spectrum. At locations where poor nutritional conditions were coupled with disturbance, the biomass was strongly reduced in selected macrofaunal size classes (class 10 and 11), while meiofaunal biomass and production were much higher, most likely due to a release from macrofaunal predation and competition pressure. As a result, the partitioning of benthic biomass and production shifted towards meiofauna

  4. Atmospheric transport of pollution to the Arctic

    International Nuclear Information System (INIS)

    Iversen, T.

    1984-01-01

    If the atmospheric processes are assumed to be nearly adiabatic, the conclusion is that the possible source areas of Arctic air pollution detected at ground level have to be situated in areas with almost the same temperature as observed in the Arctic itself. Sources south of the polar front system can only contribute to high-altitude (or upper level) Arctic pollution. The amplitude and phase of long, planetary waves are important since they determine the position of the polar front, and provide conditions for meridional transport of air at certain longitudes

  5. Recent Arctic sea level variations from satellites

    OpenAIRE

    Ole Baltazar Andersen; Gaia ePiccioni

    2016-01-01

    Sea level monitoring in the Arctic region has always been an extreme challenge for remote sensing, and in particular for satellite altimetry. Despite more than two decades of observations, altimetry is still limited in the inner Arctic Ocean. We have developed an updated version of the Danish Technical University's (DTU) Arctic Ocean altimetric sea level timeseries starting in 1993 and now extended up to 2015 with CryoSat-2 data. The time-series covers a total of 23 years, which allows higher...

  6. Arctic tides from GPS on sea ice

    OpenAIRE

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    2012-01-01

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic....

  7. The 2008 Circum-Arctic Resource Appraisal

    Science.gov (United States)

    Moore, Thomas E.; Gautier, Donald L.

    2017-11-15

    Professional Paper 1824 comprises 30 chapters by various U.S. Geological Survey authors, including introduction and methodology chapters, which together provide documentation of the geological basis and methodology of the 2008 Circum-Arctic Resource Appraisal, results of which were first released in August 2008.  Twenty-eight chapters summarize the petroleum geology and resource potential of individual, geologically defined provinces north of the Arctic Circle, including those of northern Alaska, northern Canada, east and west Greenland, and most of Arctic Russia, as well as certain offshore areas of the north Atlantic Basin and the Polar Sea. Appendixes tabulate the input and output information used during the assessment.

  8. Fate of mercury in the Arctic (FOMA)

    DEFF Research Database (Denmark)

    Skov, H.; Christensen, J.; Asmund, G.

    This report is the final reporting of the project FONA, funded by the Danish Environmental Protection Agency with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region. The aim of the project is to study the intercompartment mercury transport chain in the arctic area. From...... in the Arctic. The report focus on the surface exchange of mercury, the uptake of abiotic mercury into the biological system, and the bioaccumulation in the first steps of the food web, and the resulting distribution and time trend of mercury in selected animals feeding on various trophic levels...

  9. Ice-Rich Yedoma Permafrost: A Synthesis of Circum-Arctic Distribution and Thickness

    Science.gov (United States)

    Strauss, J.; Fedorov, A. N.; Fortier, D.; Froese, D. G.; Fuchs, M.; Grosse, G.; Günther, F.; Harden, J. W.; Hugelius, G.; Kanevskiy, M. Z.; Kholodov, A. L.; Kunitsky, V.; Laboor, S.; Lapointe Elmrabti, L.; Rivkina, E.; Robinson, J. E.; Schirrmeister, L.; Shmelev, D.; Shur, Y.; Spektor, V.; Ulrich, M.; Veremeeva, A.; Walter Anthony, K. M.; Zimov, S. A.

    2015-12-01

    Vast portions of Arctic and sub-Arctic Siberia, Alaska and the Yukon Territory are covered by ice-rich silts that are penetrated by large ice wedges, resulting from syngenetic sedimentation and freezing. Accompanied by wedge-ice growth, the sedimentation process was driven by cold continental climatic and environmental conditions in unglaciated regions during the late Pleistocene, inducing the accumulation of the unique Yedoma permafrost deposits up to 50 meter thick. Because of fast incorporation of organic material into permafrost during formation, Yedoma deposits include low-decomposed organic matter. Moreover, ice-rich permafrost deposits like Yedoma are especially prone to degradation triggered by climate changes or human activity. When Yedoma deposits degrade, large amounts of sequestered organic carbon as well as other nutrients are released and become part of active biogeochemical cycling. This could be of global significance for the climate warming, as increased permafrost thaw is likely to cause a positive feedback loop. Therefore, a detailed assessment of the Yedoma deposit volume is of importance to estimate its potential future climate response. Moreover, as a step beyond the objectives of this synthesis study, our coverage (see figure for the Yedoma domain) and thickness estimation will provide critical data to refine the Yedoma permafrost organic carbon inventory, which is assumed to have freeze-locked between 83±12 and 129±30 gigatonnes (Gt) of organic carbon. Hence, we here synthesize data on the circum-Arctic and sub-Arctic distribution and thickness of Yedoma permafrost (see figure for the Yedoma domain) in the framework of an Action Group funded by the International Permafrost Association (IPA). The quantification of the Yedoma coverage is conducted by the digitization of geomorphological and Quaternary geological maps. Further data on Yedoma thickness is contributed from boreholes and exposures reported in the scientific literature.

  10. The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.

    Science.gov (United States)

    Speelman, E N; Van Kempen, M M L; Barke, J; Brinkhuis, H; Reichart, G J; Smolders, A J P; Roelofs, J G M; Sangiorgi, F; de Leeuw, J W; Lotter, A F; Sinninghe Damsté, J S

    2009-03-01

    Enormous quantities of the free-floating freshwater fern Azolla grew and reproduced in situ in the Arctic Ocean during the middle Eocene, as was demonstrated by microscopic analysis of microlaminated sediments recovered from the Lomonosov Ridge during Integrated Ocean Drilling Program (IODP) Expedition 302. The timing of the Azolla phase (approximately 48.5 Ma) coincides with the earliest signs of onset of the transition from a greenhouse towards the modern icehouse Earth. The sustained growth of Azolla, currently ranking among the fastest growing plants on Earth, in a major anoxic oceanic basin may have contributed to decreasing atmospheric pCO2 levels via burial of Azolla-derived organic matter. The consequences of these enormous Azolla blooms for regional and global nutrient and carbon cycles are still largely unknown. Cultivation experiments have been set up to investigate the influence of elevated pCO2 on Azolla growth, showing a marked increase in Azolla productivity under elevated (760 and 1910 ppm) pCO2 conditions. The combined results of organic carbon, sulphur, nitrogen content and 15N and 13C measurements of sediments from the Azolla interval illustrate the potential contribution of nitrogen fixation in a euxinic stratified Eocene Arctic. Flux calculations were used to quantitatively reconstruct the potential storage of carbon (0.9-3.5 10(18) gC) in the Arctic during the Azolla interval. It is estimated that storing 0.9 10(18) to 3.5 10(18) g carbon would result in a 55 to 470 ppm drawdown of pCO2 under Eocene conditions, indicating that the Arctic Azolla blooms may have had a significant effect on global atmospheric pCO2 levels through enhanced burial of organic matter.

  11. Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia.

    Science.gov (United States)

    Vonk, J E; Sánchez-García, L; van Dongen, B E; Alling, V; Kosmach, D; Charkin, A; Semiletov, I P; Dudarev, O V; Shakhova, N; Roos, P; Eglinton, T I; Andersson, A; Gustafsson, O

    2012-09-06

    The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ~7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57 ± 2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44 ± 10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66 ± 16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming.

  12. Market-implied risk-neutral probabilities, actual probabilities, credit risk and news

    Directory of Open Access Journals (Sweden)

    Shashidhar Murthy

    2011-09-01

    Full Text Available Motivated by the credit crisis, this paper investigates links between risk-neutral probabilities of default implied by markets (e.g. from yield spreads and their actual counterparts (e.g. from ratings. It discusses differences between the two and clarifies underlying economic intuition using simple representations of credit risk pricing. Observed large differences across bonds in the ratio of the two probabilities are shown to imply that apparently safer securities can be more sensitive to news.

  13. Can we replace CAPM and the Three-Factor model with Implied Cost of Capital?

    OpenAIRE

    Löthman, Robert; Pettersson, Eric

    2014-01-01

    Researchers criticize predominant expected return models for being imprecise and based on fundamentally flawed assumptions. This dissertation evaluates Implied Cost of Capital, CAPM and the Three-Factor model abilities to estimate returns. We study each models expected return association to realized return and test for abnormal returns. Our sample covers the period 2000 to 2012 and includes 2916 US firms. We find that Implied Cost of Capital has a stronger association with realized returns th...

  14. LEFT-WING ASYMPTOTICS OF THE IMPLIED VOLATILITY IN THE PRESENCE OF ATOMS

    OpenAIRE

    ARCHIL GULISASHVILI

    2015-01-01

    The paper considers the asymptotic behavior of the implied volatility in stochastic asset price models with atoms. In such models, the asset price distribution has a singular component at zero. Examples of models with atoms include the constant elasticity of variance (CEV) model, jump-to-default models, and stochastic models described by processes stopped at the first hitting time of zero. For models with atoms, the behavior of the implied volatility at large strikes is similar to that in mod...

  15. Relationship of the change in implied volatility with the underlying equity index return in Thailand

    OpenAIRE

    Thakolsri, Supachock; Sethapramote, Yuthana; Jiranyakul, Komain

    2016-01-01

    In this study, we examine the relationship between the change in implied volatility index and the underlying stock index return in the Thai stock market. The data used are daily data during November 2010 to December 2013. The regression analysis is performed on stationary series. The empirical results reveal that there is evidence of a significantly negative and asymmetric relationship between the underlying stock index return and the change in implied volatility. The finding in this study gi...

  16. Modeling and Forecasting the Implied Volatility of the WIG20 Index

    OpenAIRE

    Buszkowska-Khemissi, Eliza; Płuciennik, Piotr

    2007-01-01

    The implied volatility is one of the most important notions in the financial market. It informs about the volatility forecasted by the participans of the market. In this paper we calculate the daily implied volatility from options on the WIG20 index. First we test the long memory property of the time series obtained in such a way, and then we model and forcast it as ARFIMA process

  17. Bayesian Forecasting of Options Prices: A Natural Framework for Pooling Historical and Implied Volatiltiy Information

    OpenAIRE

    Darsinos, T.; Satchell, S.E.

    2001-01-01

    Bayesian statistical methods are naturally oriented towards pooling in a rigorous way information from separate sources. It has been suggested that both historical and implied volatilities convey information about future volatility. However, typically in the literature implied and return volatility series are fed separately into models to provide rival forecasts of volatility or options prices. We develop a formal Bayesian framework where we can merge the backward looking information as r...

  18. Motor mapping of implied actions during perception of emotional body language.

    Science.gov (United States)

    Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

    2012-04-01

    Perceiving and understanding emotional cues is critical for survival. Using the International Affective Picture System (IAPS) previous TMS studies have found that watching humans in emotional pictures increases motor excitability relative to seeing landscapes or household objects, suggesting that emotional cues may prime the body for action. Here we tested whether motor facilitation to emotional pictures may reflect the simulation of the human motor behavior implied in the pictures occurring independently of its emotional valence. Motor-evoked potentials (MEPs) to single-pulse TMS of the left motor cortex were recorded from hand muscles during observation and categorization of emotional and neutral pictures. In experiment 1 participants watched neutral, positive and negative IAPS stimuli, while in experiment 2, they watched pictures depicting human emotional (joyful, fearful), neutral body movements and neutral static postures. Experiment 1 confirms the increase in excitability for emotional IAPS stimuli found in previous research and shows, however, that more implied motion is perceived in emotional relative to neutral scenes. Experiment 2 shows that motor excitability and implied motion scores for emotional and neutral body actions were comparable and greater than for static body postures. In keeping with embodied simulation theories, motor response to emotional pictures may reflect the simulation of the action implied in the emotional scenes. Action simulation may occur independently of whether the observed implied action carries emotional or neutral meanings. Our study suggests the need of controlling implied motion when exploring motor response to emotional pictures of humans. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Evidence for middle Eocene Arctic sea ice from diatoms and ice-rafted debris.

    Science.gov (United States)

    Stickley, Catherine E; St John, Kristen; Koç, Nalân; Jordan, Richard W; Passchier, Sandra; Pearce, Richard B; Kearns, Lance E

    2009-07-16

    Oceanic sediments from long cores drilled on the Lomonosov ridge, in the central Arctic, contain ice-rafted debris (IRD) back to the middle Eocene epoch, prompting recent suggestions that ice appeared in the Arctic about 46 million years (Myr) ago. However, because IRD can be transported by icebergs (derived from land-based ice) and also by sea ice, IRD records are restricted to providing a history of general ice-rafting only. It is critical to differentiate sea ice from glacial (land-based) ice as climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean-atmosphere exchanges, whereas land-based ice affects sea level and consequently ocean acidity. An earlier report assumed that sea ice was prevalent in the middle Eocene Arctic on the basis of IRD, and although somewhat preliminary supportive evidence exists, these data are neither comprehensive nor quantified. Here we show the presence of middle Eocene Arctic sea ice from an extraordinary abundance of a group of sea-ice-dependent fossil diatoms (Synedropsis spp.). Analysis of quartz grain textural characteristics further supports sea ice as the dominant transporter of IRD at this time. Together with new information on cosmopolitan diatoms and existing IRD records, our data strongly suggest a two-phase establishment of sea ice: initial episodic formation in marginal shelf areas approximately 47.5 Myr ago, followed approximately 0.5 Myr later by the onset of seasonally paced sea-ice formation in offshore areas of the central Arctic. Our data establish a 2-Myr record of sea ice, documenting the transition from a warm, ice-free environment to one dominated by winter sea ice at the start of the middle Eocene climatic cooling phase.

  20. Transnational Sea-Ice Transport in a Warmer, More Mobile Arctic

    Science.gov (United States)

    Newton, R.; Tremblay, B.; Pfirman, S. L.; DeRepentigny, P.

    2015-12-01

    As the Arctic sea ice thins, summer ice continues to shrink in its area, and multi-year ice becomes rarer, winter ice is not disappearing from the Arctic Basin. Rather, it is ever more dominated by first year ice. And each summer, as the total coverage withdraws, the first year ice is able travel faster and farther, carrying any ice-rafted material with it. Micro-organisms, sediments, pollutants and river runoff all move across the Arctic each summer and are deposited hundreds of kilometers from their origins. Analyzing Arctic sea ice drift patterns in the context of the exclusive economic zones (EEZs) of the Arctic nations raises concerns about the changing fate of "alien" ice which forms within one country's EEZ, then drifts and melts in another country's EEZ. We have developed a new data set from satellite-based ice-drift data that allows us to track groups of ice "pixels" forward from their origin to their destination, or backwards from their melting location to their point of formation. The software has been integrated with model output to extend the tracking of sea ice to include climate projections. Results indicate, for example, that Russian sea ice dominates "imports" to the EEZ of Norway, as expected, but with increasing ice mobility it is also is exported into the EEZs of other countries, including Canada and the United States. Regions of potential conflict are identified, including several national borders with extensive and/or changing transboundary sea ice transport. These data are a starting point for discussion of transborder questions raised by "alien" ice and the material it may import from one nation's EEZ to another's.

  1. Widespread release of old carbon across the Siberian Arctic echoed by its large rivers

    Directory of Open Access Journals (Sweden)

    Ö. Gustafsson

    2011-06-01

    Full Text Available Over decadal-centennial timescales, only a few mechanisms in the carbon-climate system could cause a massive net redistribution of carbon from land and ocean systems to the atmosphere in response to climate warming. The largest such climate-vulnerable carbon pool is the old organic carbon (OC stored in Arctic permafrost (perennially frozen soils. Climate warming, both predicted and now observed to be the strongest globally in the Eurasian Arctic and Alaska, causes thaw-release of old permafrost carbon from local tundra sites. However, a central challenge for the assessment of the general vulnerability of this old OC pool is to deduce any signal integrating its release over larger scales. Here we examine radiocarbon measurements of molecular soil markers exported by the five Great Russian-Arctic Rivers (Ob, Yenisey, Lena, Indigirka and Kolyma, employed as natural integrators of carbon release processes in their watersheds. The signals held in estuarine surface sediments revealed that average radiocarbon ages of n-alkanes increased east-to-west from 6400 yr BP in Kolyma to 11 400 yr BP in Ob. This is consistent with westwards trends of both warmer climate and more degraded organic matter as indicated by the ratio of high molecular weight (HMW n-alkanoic acids to HMW n-alkanes. The dynamics of Siberian permafrost can thus be probed via the molecular-radiocarbon signal as carried by Arctic rivers. Old permafrost carbon is at present vulnerable to mobilization over continental scales. Climate-induced changes in the radiocarbon fingerprint of released permafrost carbon will likely depend on changes in both permafrost coverage and Arctic soil hydraulics.

  2. Eocene climate and Arctic paleobathymetry: A tectonic sensitivity study using GISS ModelE-R

    Science.gov (United States)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2009-12-01

    The early Paleogene (65-45 million years ago, Ma) was a ‘greenhouse’ interval with global temperatures warmer than any other time in the last 65 Ma. This period was characterized by high levels of CO2, warm high-latitudes, warm surface-and-deep oceans, and an intensified hydrological cycle. Sediments from the Arctic suggest that the Eocene surface Arctic Ocean was warm, brackish, and episodically enabled the freshwater fern Azolla to bloom. The precise mechanisms responsible for the development of these conditions remain uncertain. We present equilibrium climate conditions derived from a fully-coupled, water-isotope enabled, general circulation model (GISS ModelE-R) configured for the early Eocene. We also present model-data comparison plots for key climatic variables (SST and δ18O) and analyses of the leading modes of variability in the tropical Pacific and North Atlantic regions. Our tectonic sensitivity study indicates that Northern Hemisphere climate would have been very sensitive to the degree of oceanic exchange through the seaways connecting the Arctic to the Atlantic and Tethys. By restricting these seaways, we simulate freshening of the surface Arctic Ocean to ~6 psu and warming of sea-surface temperatures by 2°C in the North Atlantic and 5-10°C in the Labrador Sea. Our results may help explain the occurrence of low-salinity tolerant taxa in the Arctic Ocean during the Eocene and provide a mechanism for enhanced warmth in the north western Atlantic. We also suggest that the formation of a volcanic land-bridge between Greenland and Europe could have caused increased ocean convection and warming of intermediate waters in the Atlantic. If true, this result is consistent with the theory that bathymetry changes may have caused thermal destabilisation of methane clathrates in the Atlantic.

  3. Brominated flame retardants in the Arctic environment--trends and new candidates.

    Science.gov (United States)

    de Wit, Cynthia A; Herzke, Dorte; Vorkamp, Katrin

    2010-07-01

    Polybrominated diphenyl ethers (PBDEs) containing two to 10 bromines are ubiquitous in the Arctic, in both abiotic and biotic samples. Hexabromocyclododecane (HBCD) is also ubiquitous in the Arctic, with the gamma-HBCD isomer predominating in air, the alpha-HBCD isomer predominating in biota and similar concentrations of alpha-, beta- and gamma-HBCD found in marine sediments. Other brominated flame retardants (BFRs) found in some Arctic samples are polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), hexabromobenzene (HxBBz), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH). Temporal trends of tetra- to heptaBDEs and HBCD show increasing concentrations or a tendency to levelling off depending on the matrix (air, sediment, biota) and location, but no uniform picture for the Arctic emerges. BDE-209 concentrations are increasing in air. PBDEs and HBCD spatial trends in seabirds and marine mammals are similar to those seen previously for polychlorinated biphenyls (PCBs), with highest concentrations found in organisms from East Greenland and Svalbard. These trends indicate western Europe and eastern North America as important source regions of these compounds via long range atmospheric transport and ocean currents. Latitudinal trends showed lower concentrations and fluxes of PBDEs at higher latitudes. The tetra-hexaBDEs and alpha-HBCD biomagnify in Arctic food webs. Results for BDE-209 are more conflicting, showing either only low or no biomagnification potential. PBDE and HBCD concentrations are lower in terrestrial organisms and higher in marine top predators such as some killer whale populations in Alaska and glaucous gulls from the Barents Sea area. Higher concentrations are seen near populated areas indicating local sources. Findings of BTBPE, HxBBz, PBEB, PBT and TBECH in seabirds and/or marine mammals indicate that these compounds reach the

  4. Fish and crustaceans in northeast Greenland lakes with special emphasis on interactions between Arctic charr (Salvelinus alpinus), Lepidurus arcticus and benthic chydorids

    DEFF Research Database (Denmark)

    Jeppesen, E.; Christoffersen, K.; Landkildehus, F.

    2001-01-01

    We studied the trophic structure in the pelagial and crustacean remains in the surface 1 cm of the sediment of 13 shallow, high arctic lakes in northeast Greenland (74 N). Seven lakes were fishless, while the remaining six hosted a dwarf form of Arctic charr (Salvelinus alpinus). In fishless lakes...... sp. in lakes with Lepidurus, while they were abundant in lakes with fish. The low abundance in fishless lakes could not be explained by damage of crustacean remains caused by Lepidurus feeding in the sediment, because remains of the more soft-shelled, pelagic-living Daphnia were abundant...... in the sediment of these lakes. No significant differences between lakes with and without fish were found in chlorophyll a, total phosphorus, total nitrogen, conductivity or temperature, suggesting that the observed link between Lepidurus arcticus and the benthic crustacean community is causal. Consequently...

  5. Levels and trends of contaminants in humans of the Arctic.

    Science.gov (United States)

    Gibson, Jennifer; Adlard, Bryan; Olafsdottir, Kristin; Sandanger, Torkjel Manning; Odland, Jon Øyvind

    2016-01-01

    The Arctic Monitoring and Assessment Programme (AMAP) is one of the six working groups established under the Arctic Council. AMAP is tasked with monitoring the levels of contaminants present in the Arctic environment and people as well as assessing their effects on a continuous basis, and reporting these results regularly. Most of the presented data have been collected over the last 20 years and are from all eight Arctic countries. Levels of contaminants appear to be declining in some of the monitored Arctic populations, but it is not consistent across the Arctic. Most Arctic populations continue to experience elevated levels of these contaminants compared to other populations monitored globally. There are certain contaminants, such as perfluorinated compounds and polybrominated diphenyl ethers, which are still increasing in Arctic populations. These contaminants require more investigation to find out the predominant and important sources of exposure, and whether they are being transported to the Arctic through long-range transport in the environment.

  6. Radioactive contamination in the Arctic - Present situation and future challenges

    International Nuclear Information System (INIS)

    Strand, P.

    2002-01-01

    There is currently a focus on radioactivity and the Arctic region. The reason for this is the high number of nuclear sources in parts of the Arctic and the vulnerability of Arctic systems to radioactive contamination. The Arctic environment is also perceived as a wilderness and the need for the protection of this wilderness against contamination is great. In 1991, the International Arctic Environmental Protection Strategy (IAEPS) was launched and the Arctic Monitoring and Assessment Programme (AMAP) established. AMAP is undertaking an assessment of the radioactive contamination of the Arctic and its radiological consequences. This paper summarises some of current knowledge about sources of radioactive contamination, vulnerability, exposure of man, and potential sources for radioactive contamination within Arctic and some views on the future needs for work concerning radioactivity in Arctic. (author)

  7. Arctic tipping points in an Earth system perspective.

    Science.gov (United States)

    Wassmann, Paul; Lenton, Timothy M

    2012-02-01

    We provide an introduction to the volume The Arctic in the Earth System perspective: the role of tipping points. The terms tipping point and tipping element are described and their role in current science, general debates, and the Arctic are elucidated. From a wider perspective, the volume focuses upon the role of humans in the Arctic component of the Earth system and in particular the envelope for human existence, the Arctic ecosystems. The Arctic climate tipping elements, the tipping elements in Arctic ecosystems and societies, and the challenges of governance and anticipation are illuminated through short summaries of eight publications that derive from the Arctic Frontiers conference in 2011 and the EU FP7 project Arctic Tipping Points. Then some ideas based upon resilience thinking are developed to show how wise system management could ease pressures on Arctic systems in order to keep them away from tipping points.

  8. Acoustic Monitoring of the Arctic Ice Cap

    Science.gov (United States)

    Porter, D. L.; Goemmer, S. A.; Chayes, D. N.

    2012-12-01

    Introduction The monitoring of the Arctic Ice Cap is important economically, tactically, and strategically. In the scenario of ice cap retreat, new paths of commerce open, e.g. waterways from Northern Europe to the Far East. Where ship-going commerce is conducted, the U.S. Navy and U.S. Coast Guard have always stood guard and been prepared to assist from acts of nature and of man. It is imperative that in addition to measuring the ice from satellites, e.g. Icesat, that we have an ability to measure the ice extent, its thickness, and roughness. These parameters play an important part in the modeling of the ice and the processes that control its growth or shrinking and its thickness. The proposed system consists of three subsystems. The first subsystem is an acoustic source, the second is an array of geophones and the third is a system to supply energy and transmit the results back to the analysis laboratory. The subsystems are described below. We conclude with a plan on how to tackle this project and the payoff to the ice cap modeler and hence the users, i.e. commerce and defense. System Two historically tested methods to generate a large amplitude multi-frequency sound source include explosives and air guns. A new method developed and tested by the University of Texas, ARL is a combustive Sound Source [Wilson, et al., 1995]. The combustive sound source is a submerged combustion chamber that is filled with the byproducts of the electrolysis of sea water, i.e. Hydrogen and Oxygen, an explosive mixture which is ignited via a spark. Thus, no additional compressors, gases, or explosives need to be transported to the Arctic to generate an acoustic pulse capable of the sediment and the ice. The second subsystem would be geophones capable of listening in the O(10 Hz) range and transmitting that data back to the laboratory. Thus two single arrays of geophones arranged orthogonal to each other with a range of 1000's of kilometers and a combustive sound source where the two

  9. Arctic and Southern Ocean Sea Ice Concentrations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly sea ice concentration for Arctic (1901 to 1995) and Southern oceans (1973 to 1990) were digitized on a standard 1-degree grid (cylindrical projection) to...

  10. Arctic Climate and Atmospheric Planetary Waves

    Science.gov (United States)

    Cavalieri, D. J.; Haekkinen, S.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave 1 pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach for determining significant forcing patterns of sea ice and high-latitude variability.

  11. Historical Arctic and Antarctic Surface Observational Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This product consists of meteorological data from 105 Arctic weather stations and 137 Antarctic stations, extracted from the National Climatic Data Center (NCDC)'s...

  12. Loss of sea ice in the Arctic.

    Science.gov (United States)

    Perovich, Donald K; Richter-Menge, Jacqueline A

    2009-01-01

    The Arctic sea ice cover is in decline. The areal extent of the ice cover has been decreasing for the past few decades at an accelerating rate. Evidence also points to a decrease in sea ice thickness and a reduction in the amount of thicker perennial sea ice. A general global warming trend has made the ice cover more vulnerable to natural fluctuations in atmospheric and oceanic forcing. The observed reduction in Arctic sea ice is a consequence of both thermodynamic and dynamic processes, including such factors as preconditioning of the ice cover, overall warming trends, changes in cloud coverage, shifts in atmospheric circulation patterns, increased export of older ice out of the Arctic, advection of ocean heat from the Pacific and North Atlantic, enhanced solar heating of the ocean, and the ice-albedo feedback. The diminishing Arctic sea ice is creating social, political, economic, and ecological challenges.

  13. Arctic Ocean Regional Climatology (NCEI Accession 0115771)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To provide an improved oceanographic foundation and reference for multi-disciplinary studies of the Arctic Ocean, NCEI developed a new set of high-resolution...

  14. Arctic Landfast Sea Ice 1953-1998

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The files in this data set contain landfast sea ice data (monthly means) gathered from both Russian Arctic and Antarctic Research Institute (AARI) and Canadian Ice...

  15. Arctic Marine Transportation Program 1979-1986

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this program was to collect data relevant to developing year-round transportation capabilities in the Arctic Ocean. The US Maritime Administration...

  16. Arctic Sea Ice Freeboard and Thickness

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides measurements of sea ice freeboard and sea ice thickness for the Arctic region. The data were derived from measurements made by from the Ice,...

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

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, Aaron T. [Warnell School of Forest Resources, University of Georgia, Athens, GA 30602-2152 (United States)]. E-mail: afisk@forestry.uga.edu; Wit, Cynthia A. de [Department of Applied Environmental Science, Stockholm University, Stockholm (Sweden); Wayland, Mark [Prairie and Northern Wildlife Research Centre, Environment Canada, 115 Perimeter Rd., Saskatoon, SK, S7N 0X4 (Canada); Kuzyk, Zou Zou [Environmental Sciences Group, Royal Military College of Canada, Kingston, ON, K7K 7B4 (Canada); Burgess, Neil [Canadian Wildlife Service, Environment Canada, 6 Bruce St. Mt. Pearl, NL, A1N4T3 (Canada); Letcher, Robert [National Wildlife Research Centre, Environment Canada, Ottawa, ON, K1A 0H3 (Canada); Braune, Birgit [National Wildlife Research Centre, Environment Canada, Ottawa, ON, Canada K1A 0H3 (Canada); Norstrom, Ross [National Wildlife Research Centre, Environment Canada, Ottawa, ON, K1A 0H3 (Canada); Blum, Susan Polischuk [Office of Research Services, University of Saskatchewan, Saskatoon, SK, S7N 4J8 (Canada); Sandau, Courtney [Jacques Whitford Limited, Calgary, AB, T2R 0E4 (Canada); Lie, Elisabeth [National Veterinary Institute, P.O. Box 8156, Dep 0033, Oslo (Norway); Larsen, Hans Jorgen S. [Norwegian School of Veterinary Science, P.O. Box 8146, Dep 0033, Oslo (Norway); Skaare, Janneche Utne [National Veterinary Institute, P.O. Box 8156, Dep 0033, Oslo (Norway); Norwegian School of Veterinary Science, P.O. Box 8146, Dep 0033, Oslo (Norway); Muir, Derek C.G. [National Water Research Institute, Environment Canada, Burlington, ON, L7R 4A6 (Canada)

    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

  19. An Ocean Basin of Dirt? Using Molecular Biomarkers and Radiocarbon to Identify Organic Carbon Sources and their Preservation in the Arctic Ocean

    Science.gov (United States)

    Harvey, H.; Belicka, L. L.

    2005-12-01

    In the modern Arctic Ocean, primary production in waters over the broad continental shelves and under ice contributes an estimated 250 Mt/yr of POC to Arctic waters. The delivery of terrestrial material from large rivers, ice transport and through coastal erosion adds at least an additional 12 Mt/yr of POC. Although the marine organic carbon signal in Arctic Ocean exceeds that of terrestrial carbon by an order or magnitude or more, recent evidence suggests that this balance is not maintained and significant fractions of terrestrial carbon is preserved in sediments. Using an integrated approach combining lipid biomarkers and radiocarbon dating in particles and sediments, the process of organic carbon recycling and historical changes in its sources and preservation has been examined. A suite of lipid biomarkers in particles and sediments of western Arctic shelves and basins were measured and principle components analysis (PCA) used to allow a robust comparison among the 120+ individual compounds to assign organic sources and relative inputs. Offshore particles from the chlorophyll maximum contained abundant algal markers (e.g. 20:5 and 22:6 FAMEs), low concentrations of terrestrial markers (amyrins and 24-ethylcholest-5-en-3b-ol), and reflected modern 14C values. Particles present in deeper halocline waters also reflect marine production, but a portion of older, terrestrial carbon accompanies the sinking of the spring bloom. Surface and deeper sediments of basins contain older organic carbon and low concentrations of algal biomarkers, suggesting that marine carbon produced in surface waters is rapidly recycled. Taken together, these observations suggest that marine derived organic matter produced in shallow waters fuels carbon cycling, but relatively small amounts are preserved in sediments. As a result, the organic carbon preserved in sediments contrasts sharply to that typically observed in lower latitudes, with an increasing terrestrial signature with distance

  20. Arctic tides from GPS on sea ice

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing o......-gauges and altimetry data. Furthermore, we prove that the geodetic reference ellipsoid WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

  1. Coarse mode aerosols in the High Arctic

    Science.gov (United States)

    Baibakov, K.; O'Neill, N. T.; Chaubey, J. P.; Saha, A.; Duck, T. J.; Eloranta, E. W.

    2014-12-01

    Fine mode (submicron) aerosols in the Arctic have received a fair amount of scientific attention in terms of smoke intrusions during the polar summer and Arctic haze pollution during the polar winter. Relatively little is known about coarse mode (supermicron) aerosols, notably dust, volcanic ash and sea salt. Asian dust is a regular springtime event whose optical and radiative forcing effects have been fairly well documented at the lower latitudes over North America but rarely reported for the Arctic. Volcanic ash, whose socio-economic importance has grown dramatically since the fear of its effects on aircraft engines resulted in the virtual shutdown of European civil aviation in the spring of 2010 has rarely been reported in the Arctic in spite of the likely probability that ash from Iceland and the Aleutian Islands makes its way into the Arctic and possibly the high Arctic. Little is known about Arctic sea salt aerosols and we are not aware of any literature on the optical measurement of these aerosols. In this work we present preliminary results of the combined sunphotometry-lidar analysis at two High Arctic stations in North America: PEARL (80°N, 86°W) for 2007-2011 and Barrow (71°N,156°W) for 2011-2014. The multi-years datasets were analyzed to single out potential coarse mode incursions and study their optical characteristics. In particular, CIMEL sunphotometers provided coarse mode optical depths as well as information on particle size and refractive index. Lidar measurements from High Spectral Resolution lidars (AHSRL at PEARL and NSHSRL at Barrow) yielded vertically resolved aerosol profiles and gave an indication of particle shape and size from the depolarization ratio and color ratio profiles. Additionally, we employed supplementary analyses of HYSPLIT backtrajectories, OMI aerosol index, and NAAPS (Navy Aerosol Analysis and Prediction System) outputs to study the spatial context of given events.

  2. Studying ocean acidification in the Arctic Ocean

    Science.gov (United States)

    Robbins, Lisa

    2012-01-01

    The U.S. Geological Survey (USGS) partnership with the U.S. Coast Guard Ice Breaker Healey and its United Nations Convention Law of the Sea (UNCLOS) cruises has produced new synoptic data from samples collected in the Arctic Ocean and insights into the patterns and extent of ocean acidification. This framework of foundational geochemical information will help inform our understanding of potential risks to Arctic resources due to ocean acidification.

  3. Status and Impacts of Arctic Freshwater Export

    Science.gov (United States)

    Haine, T. W. N.

    2017-12-01

    Large freshwater anomalies clearly exist in the Arctic Ocean. For example, liquid freshwater has accumulated in the Beaufort Gyre in the decade of the 2000s compared to 1980-2000, with an extra ≈5000 km3—about 25%—being stored. The sources of freshwater to the Arctic from precipitation and runoff have increased between these periods (most of the evidence comes from models). Despite flux increases from 2001 to 2011, it is uncertain if the marine freshwater source through Bering Strait for the 2000s has changed, as observations in the 1980s and 1990s are incomplete. The marine freshwater fluxes draining the Arctic through Fram and Davis straits are also insignificantly different. In this way, the balance of sources and sinks of freshwater to the Arctic, Canadian Arctic Archipelago (CAA), and Baffin Bay shifted to about 1200±730 km3yr-1 freshening the region, on average, during the 2000s. The observed accumulation of liquid freshwater is consistent with this increased supply and the loss of freshwater from sea ice (Figure, right). Evidence exists that such discharges can impact the Atlantic meridional overturning circulation, and hence Atlantic sector climate. Nevertheless, it appears that the observed AMOC variability since 2004, when high quality measurements began, is not attributable to anthropogenic influence. This work is based on, and updated from, Haine et al. (2015), Carmack et al. (2016), and Haine (2016). Haine, T. W. N. Ocean science: Vagaries of Atlantic overturning. Nature Geoscience, 9, 479-480, 10.1038/ngeo2748, 2016. T. W. N. Haine et al., Arctic Freshwater Export: Status, Mechanisms, and Prospects, Global Planetary Change, 125, 13-35, 10.1016/j.glopacha.2014.11.013, 2015. E. Carmack et al., Fresh water and its role in the Arctic Marine System: sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans. J. G. Res. Biogeosciences, 10.1002/2015JG003140, 2016.

  4. 2nd International Arctic Ungulate Conference

    OpenAIRE

    Anonymous, A.

    1996-01-01

    The 2nd International Arctic Ungulate Conference was held 13-17 August 1995 on the University of Alaska Fairbanks campus. The Institute of Arctic Biology and the Alaska Cooperative Fish and Wildlife Research Unit were responsible for organizing the conference with assistance from biologists with state and federal agencies and commercial organizations. David R. Klein was chair of the conference organizing committee. Over 200 people attended the conference, coming from 10 different countries. T...

  5. Arctic Ocean data in CARINA

    Directory of Open Access Journals (Sweden)

    S. Jutterström

    2010-02-01

    Full Text Available The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH, oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as applied adjustments.

  6. Zooplankton in the Arctic outflow

    Science.gov (United States)

    Soloviev, K. A.; Dritz, A. V.; Nikishina, A. B.

    2009-04-01

    Climate changes in the Arctic cause the changes in the current system that may have cascading effect on the structure of plankton community and consequently on the interlinked and delicately balanced food web. Zooplankton species are by definition incapable to perform horizontal moving. Their transport is connected with flowing water. There are zooplankton species specific for the definite water masses and they can be used as markers for the different currents. That allows us to consider zooplankton community composition as a result of water mixing in the studied area. Little is known however about the mechanisms by which spatial and temporal variability in advection affect dynamics of local populations. Ice conditions are also very important in the function of pelagic communities. Melting time is the trigger to all "plankton blooming" processes, and the duration of ice-free conditions determines the food web development in the future. Fram Strait is one of the key regions for the Arctic: the cold water outflow comes through it with the East Greenland Current and meets warm Atlantic water, the West Spitsbergen Current, producing complicated hydrological situation. During 2007 and 2008 we investigated the structure functional characteristics of zooplankton community in the Fram Strait region onboard KV "Svalbard" (April 2007, April and May 2008) and RV "Jan Mayen" (May 2007, August 2008). This study was conducted in frame of iAOOS Norway project "Closing the loop", which, in turn, was a part of IPY. During this cruises multidisciplinary investigations were performed, including sea-ice observations, CTD and ADCP profiling, carbon flux, nutrients and primary production measurements, phytoplankton sampling. Zooplankton was collected with the Hydro-Bios WP2 net and MultiNet Zooplankton Sampler, (mouth area 0.25 m2, mesh size 180 um).Samples were taken from the depth strata of 2000-1500, 1500-1000, 1000-500,500-200, 200-100, 100-60, 60-30, 30-0 m. Gut fluorescence

  7. The great challenges in Arctic Ocean paleoceanography

    International Nuclear Information System (INIS)

    Stein, Ruediger

    2011-01-01

    Despite the importance of the Arctic in the climate system, the data base we have from this area is still very weak, and large parts of the climate history have not been recovered at all in sedimentary sections. In order to fill this gap in knowledge, international, multidisciplinary expeditions and projects for scientific drilling/coring in the Arctic Ocean are needed. Key areas and approaches for drilling and recovering undisturbed and complete sedimentary sequences are depth transects across the major ocean ridge systems, i.e., the Lomonosov Ridge, the Alpha-Mendeleev Ridge, and the Chukchi Plateau/Northwind Ridge, the Beaufort, Kara and Laptev sea continental margins, as well as the major Arctic gateways towards the Atlantic and Pacific oceans. The new detailed climate records from the Arctic Ocean spanning time intervals from the Late Cretaceous/Paleogene Greenhouse world to the Neogene-Quaternary Icehouse world and representing short- and long-term climate variability on scales from 10 to 10 6 years, will give new insights into our understanding of the Arctic Ocean within the global climate system and provide an opportunity to test the performance of climate models used to predict future climate change. With this, studying the Arctic Ocean is certainly one of the major challenges in climate research for the coming decades.

  8. Recent Changes in the Arctic Melt Season

    Science.gov (United States)

    Stroeve, Julienne; Markus, Thorsten; Meier, Walter N.; Miller, Jeff

    2007-01-01

    Melt-season duration, melt-onset and freeze-up dates are derived from satellite passive microwave data and analyzed from 1979 to 2005 over Arctic sea ice. Results indicate a shift towards a longer melt season, particularly north of Alaska and Siberia, corresponding to large retreats of sea ice observed in these regions. Although there is large interannual and regional variability in the length of the melt season, the Arctic is experiencing an overall lengthening of the melt season at a rate of about 2 weeks decade(sup -1). In fact, all regions in the Arctic (except for the central Arctic) have statistically significant (at the 99% level or higher) longer melt seasons by greater than 1 week decade(sup -1). The central Arctic shows a statistically significant trend (at the 98% level) of 5.4 days decade(sup -1). In 2005 the Arctic experienced its longest melt season, corresponding with the least amount of sea ice since 1979 and the warmest temperatures since the 1880s. Overall, the length of the melt season is inversely correlated with the lack of sea ice seen in September north of Alaska and Siberia, with a mean correlation of -0.8.

  9. Meiofauna metabolism in suboxic sediments: currently overestimated.

    Directory of Open Access Journals (Sweden)

    Ulrike Braeckman

    Full Text Available Oxygen is recognized as a structuring factor of metazoan communities in marine sediments. The importance of oxygen as a controlling factor on meiofauna (32 µm-1 mm in size respiration rates is however less clear. Typically, respiration rates are measured under oxic conditions, after which these rates are used in food web studies to quantify the role of meiofauna in sediment carbon turnover. Sediment oxygen concentration ([O(2] is generally far from saturated, implying that (1 current estimates of the role of meiofauna in carbon cycling may be biased and (2 meiofaunal organisms need strategies to survive in oxygen-stressed environments. Two main survival strategies are often hypothesized: 1 frequent migration to oxic layers and 2 morphological adaptation. To evaluate these hypotheses, we (1 used a model of oxygen turnover in the meiofauna body as a function of ambient [O(2], and (2 performed respiration measurements at a range of [O(2] conditions. The oxygen turnover model predicts a tight coupling between ambient [O(2] and meiofauna body [O(2] with oxygen within the body being consumed in seconds. This fast turnover favors long and slender organisms in sediments with low ambient [O(2] but even then frequent migration between suboxic and oxic layers is for most organisms not a viable strategy to alleviate oxygen limitation. Respiration rates of all measured meiofauna organisms slowed down in response to decreasing ambient [O(2], with Nematoda displaying the highest metabolic sensitivity for declining [O(2] followed by Foraminifera and juvenile Gastropoda. Ostracoda showed a behavioral stress response when ambient [O(2] reached a critical level. Reduced respiration at low ambient [O(2] implies that meiofauna in natural, i.e. suboxic, sediments must have a lower metabolism than inferred from earlier respiration rates conducted under oxic conditions. The implications of these findings are discussed for the contribution of meiofauna to carbon

  10. Implied adjusted volatility functions: Empirical evidence from Australian index option market

    Science.gov (United States)

    Harun, Hanani Farhah; Hafizah, Mimi

    2015-02-01

    This study aims to investigate the implied adjusted volatility functions using the different Leland option pricing models and to assess whether the use of the specified implied adjusted volatility function can lead to an improvement in option valuation accuracy. The implied adjusted volatility is investigated in the context of Standard and Poor/Australian Stock Exchange (S&P/ASX) 200 index options over the course of 2001-2010, which covers the global financial crisis in the mid-2007 until the end of 2008. Both in- and out-of-sample resulted in approximately similar pricing error along the different Leland models. Results indicate that symmetric and asymmetric models of both moneyness ratio and logarithmic transformation of moneyness provide the overall best result in both during and post-crisis periods. We find that in the different period of interval (pre-, during and post-crisis) is subject to a different implied adjusted volatility function which best explains the index options. Hence, it is tremendously important to identify the intervals beforehand in investigating the implied adjusted volatility function.

  11. Analysing Discursive Practices in Legal Research: How a Single Remark Implies a Paradigm

    Directory of Open Access Journals (Sweden)

    Paul van den Hoven

    2017-12-01

    Full Text Available Different linguistic theories of meaning (semantic theories imply different methods to discuss meaning. Discussing meaning is what legal practitioners frequently do to decide legal issues and, subsequently, legal scholars analyse in their studies these discursive practices of parties, judges and legal experts. Such scholarly analysis reveals a methodical choice on how to discuss meaning and therefore implies positioning oneself towards a semantic theory of meaning, whether the scholar is aware of this or not. Legal practitioners may not be bound to be consistent in their commitment to semantic theories, as their task is to decide legal issues. Legal scholars, however, should be consistent because commitment to a semantic theory implies a distinct position towards important legal theoretical doctrines. In this paper three examples are discussed that require an articulated position of the legal scholar because the discursive practices of legal practitioners show inconsistencies. For each of these examples it can be shown that a scholar’s methodic choice implies commitment to a specific semantic theory, and that adopting such a theory implies a distinct position towards the meaning of the Rule of Law, the separation of powers doctrine and the institutional position of the judge.

  12. Scientific Discoveries in the Central Arctic Ocean Based on Seafloor Mapping Carried out to Support Article 76 Extended Continental Shelf Claims (Invited)

    Science.gov (United States)

    Jakobsson, M.; Mayer, L. A.; Marcussen, C.

    2013-12-01

    Despite the last decades of diminishing sea-ice cover in the Arctic Ocean, ship operations are only possible in vast sectors of the central Arctic using the most capable polar-class icebreakers. There are less than a handful of these icebreakers outfitted with modern seafloor mapping equipment. This implies either fierce competition between those having an interest in using these icebreakers for investigations of the shape and properties of Arctic Ocean seafloor or, preferably, collaboration. In this presentation examples will be shown of scientific discoveries based on mapping data collected during Arctic Ocean icebreaker expeditions carried out for the purpose of substantiating claims for an extended continental shelf under United Nations Convention of the Law of the Sea (UNCLOS) Article 76. Scientific results will be presented from the suite of Lomonosov Ridge off Greenland (LOMROG) expeditions (2007, 2009, and 2012), shedding new light on Arctic Ocean oceanography and glacial history. The Swedish icebreaker Oden was used in collaboration between Sweden and Denmark during LOMROG to map and sample portions of the central Arctic Ocean; specifically focused on the Lomonosov Ridge north of Greenland. While the main objective of the Danish participation was seafloor and sub-seabed mapping to substantiate their Article 76 claim, LOMROG also included several scientific components, with scientists from both countries involved. Other examples to be presented are based on data collected using US Coast Guard Cutter Healy, which for several years has carried out mapping in the western Arctic Ocean for the US continental shelf program. All bathymetric data collected with Oden and Healy have been contributed to the International Bathymetric Chart of the Arctic Ocean (IBCAO). This is also the case for bathymetric data collected by Canadian Coast Guard Ship Louis S. St-Laurent for Canada's extended continental shelf claim. Together, the bathymetric data collected during these

  13. U.S. Arctic research in a technological age

    International Nuclear Information System (INIS)

    Johnson, P.L.

    1993-01-01

    The United States Arctic Research Commission was established in 1984 primarily as an advisory agency. An Interagency Arctic Research Policy Committee is one of the main recipients of the Commission's recommendations. The Committee formulated an Arctic research policy calling for research focused on national security concerns, regional development with minimal environmental or adverse social impact, and scientific research on Arctic phenomena and processes. In basic science, emphasis is placed on the need to understand Arctic processes as part of the global earth system. These processes include those that affect and are affected by climatic change. A new research program in Arctic systems science has three components: paleoenvironmental studies on ice core from Greenland; ocean-atmosphere interactions; and land-atmosphere interactions. The Commission also recognizes a need to focus on issues relevant to the Arctic as an integral component of the world economic system, since the Arctic is a significant source of petroleum and minerals. The Commission recommended that the Committee develop an Arctic engineering research plan with emphasis on such topics as oil spill prevention, waste disposal, small-scale power generation, and Arctic construction techniques. The USA is also cooperating in international Arctic research through the International Arctic Science Committee, the Arctic Environmental Protection Strategy, and the North Pacific Marine Science Organization

  14. OU3 sediment dating and sedimentation rates

    International Nuclear Information System (INIS)

    Blair, R.B.; Wolaver, H.A.; Burger, V.M.

    1994-01-01

    Environmental Technologies at Rocky Flats Environmental Technology Site (RFS) investigated the sediment history of Standley Lake, Great Western Reservoir, and Mower Reservoir using 137 Cs and 239,240 Pu global fall-out as dating indicators. These Colorado Front Range reservoirs have been the subject of study by various city, state and national agencies due to suspected Department of Energy Rocky Flats Plant impacts. We performed sediment dating as part of the RCRA Facility Investigation/Remedial Investigation Report for Operable Unit 3. A sediment chronology profile assists scientist in determining the year of sedimentation for a particular peak concentration of contaminants. Radioisotope sediment dating for the three reservoirs indicated sedimentation rates of 0.7 to 0.8 in./yr. for Standley Lake (SL), 0.9 in./yr. for Great Western Reservoir (GWR), and 0.3 in./yr. in Mower Reservoir (MR). RFS sediment dating for Operable Unit 3 compared favorably with the Hardy, Livingston, Burke, and Volchok Standley Lake study. This report describes the cesium/plutonium sediment dating method, estimates sedimentation rates for Operable Unit 3 reservoirs, and compares these results to previous investigations

  15. Arctic summer school onboard an icebreaker

    Science.gov (United States)

    Alexeev, Vladimir A.; Repina, Irina A.

    2014-05-01

    The International Arctic Research Center (IARC) of the University of Alaska Fairbanks conducted a summer school for PhD students, post-docs and early career scientists in August-September 2013, jointly with an arctic expedition as a part of NABOS project (Nansen and Amundsen Basin Observational System) onboard the Russian research vessel "Akademik Fedorov". Both the summer school and NABOS expedition were funded by the National Science Foundation. The one-month long summer school brought together graduate students and young scientists with specialists in arctic oceanography and climate to convey to a new generation of scientists the opportunities and challenges of arctic climate observations and modeling. Young scientists gained hands-on experience during the field campaign and learned about key issues in arctic climate from observational, diagnostic, and modeling perspectives. The summer school consisted of background lectures, participation in fieldwork and mini-projects. The mini-projects were performed in collaboration with summer school instructors and members of the expedition. Key topics covered in the lectures included: - arctic climate: key characteristics and processes; - physical processes in the Arctic Ocean; - sea ice and the Arctic Ocean; - trace gases, aerosols, and chemistry: importance for climate changes; - feedbacks in the arctic system (e.g., surface albedo, clouds, water vapor, circulation); - arctic climate variations: past, ongoing, and projected; - global climate models: an overview. An outreach specialist from the Miami Science Museum was writing a blog from the icebreaker with some very impressive statistics (results as of January 1, 2014): Total number of blog posts: 176 Blog posts written/contributed by scientists: 42 Blog views: 22,684 Comments: 1,215 Number of countries who viewed the blog: 89 (on 6 continents) The 33-day long NABOS expedition started on August 22, 2013 from Kirkenes, Norway. The vessel ("Akademik Fedorov") returned to

  16. ArcticDEM Validation and Accuracy Assessment

    Science.gov (United States)

    Candela, S. G.; Howat, I.; Noh, M. J.; Porter, C. C.; Morin, P. J.

    2017-12-01

    ArcticDEM comprises a growing inventory Digital Elevation Models (DEMs) covering all land above 60°N. As of August, 2017, ArcticDEM had openly released 2-m resolution, individual DEM covering over 51 million km2, which includes areas of repeat coverage for change detection, as well as over 15 million km2 of 5-m resolution seamless mosaics. By the end of the project, over 80 million km2 of 2-m DEMs will be produced, averaging four repeats of the 20 million km2 Arctic landmass. ArcticDEM is produced from sub-meter resolution, stereoscopic imagery using open source software (SETSM) on the NCSA Blue Waters supercomputer. These DEMs have known biases of several meters due to errors in the sensor models generated from satellite positioning. These systematic errors are removed through three-dimensional registration to high-precision Lidar or other control datasets. ArcticDEM is registered to seasonally-subsetted ICESat elevations due its global coverage and high report accuracy ( 10 cm). The vertical accuracy of ArcticDEM is then obtained from the statistics of the fit to the ICESat point cloud, which averages -0.01 m ± 0.07 m. ICESat, however, has a relatively coarse measurement footprint ( 70 m) which may impact the precision of the registration. Further, the ICESat data predates the ArcticDEM imagery by a decade, so that temporal changes in the surface may also impact the registration. Finally, biases may exist between different the different sensors in the ArcticDEM constellation. Here we assess the accuracy of ArcticDEM and the ICESat registration through comparison to multiple high-resolution airborne lidar datasets that were acquired within one year of the imagery used in ArcticDEM. We find the ICESat dataset is performing as anticipated, introducing no systematic bias during the coregistration process, and reducing vertical errors to within the uncertainty of the airborne Lidars. Preliminary sensor comparisons show no significant difference post coregistration

  17. The Impact of Jump Distributions on the Implied Volatility of Variance

    DEFF Research Database (Denmark)

    Nicolato, Elisa; Pisani, Camilla; Pedersen, David Sloth

    2017-01-01

    We consider a tractable affine stochastic volatility model that generalizes the seminal Heston (1993) model by augmenting it with jumps in the instantaneous variance process. In this framework, we consider both realized variance options and VIX options, and we examine the impact of the distribution...... of jumps on the associated implied volatility smile. We provide sufficient conditions for the asymptotic behavior of the implied volatility of variance for small and large strikes. In particular, by selecting alternative jump distributions, we show that one can obtain fundamentally different shapes...

  18. Moment generating functions and Normalized implied volatilities: unification and extension via Fukasawa's pricing formula

    OpenAIRE

    De Marco, Stefano; Martini, Claude

    2017-01-01

    We extend the model-free formula of [Fukasawa 2012] for $\\mathbb E[\\Psi(X_T)]$, where $X_T=\\log S_T/F$ is the log-price of an asset, to functions $\\Psi$ of exponential growth. The resulting integral representation is written in terms of normalized implied volatilities. Just as Fukasawa's work provides rigourous ground for Chriss and Morokoff's (1999) model-free formula for the log-contract (related to the Variance swap implied variance), we prove an expression for the moment generating functi...

  19. An Hilbert space approach for a class of arbitrage free implied volatilities models

    OpenAIRE

    Brace, A.; Fabbri, G.; Goldys, B.

    2007-01-01

    We present an Hilbert space formulation for a set of implied volatility models introduced in \\cite{BraceGoldys01} in which the authors studied conditions for a family of European call options, varying the maturing time and the strike price $T$ an $K$, to be arbitrage free. The arbitrage free conditions give a system of stochastic PDEs for the evolution of the implied volatility surface ${\\hat\\sigma}_t(T,K)$. We will focus on the family obtained fixing a strike $K$ and varying $T$. In order to...

  20. "Recent" macrofossil remains from the Lomonosov Ridge, central Arctic Ocean

    Science.gov (United States)

    Le Duc, Cynthia; de Vernal, Anne; Archambault, Philippe; Brice, Camille; Roberge, Philippe

    2016-04-01

    years as suggested by the radiocarbon dating of the upper centimeter of the sediment in PS87/030-2 (7792 ± 59 14C years BP), PS87/055-1 (3897 ± 41 14C years BP), and PS87/099-4 (1421 ± 66 14C years BP). Reference Stein, R. (Ed.), 2015. The Expedition PS87 of the Research Vessel Polarstern to the Arctic Ocean in 2014, Reports on Polar and Marine Research 688, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 273 pp (http://epic.awi.de/37728/1/BzPM_0688_2015.pdf).

  1. Petroleum prospectivity of the Canada Basin, Arctic Ocean

    Science.gov (United States)

    Grantz, Arthur; Hart, Patrick E.

    2012-01-01

    Reconnaissance seismic reflection data indicate that Canada Basin is a >700,000 sq. km. remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed across the northern part of the Amerasia Basin between about 127 and 89-83.5 Ma. Canada Basin was filled by Early Jurassic to Holocene detritus from the Beaufort-Mackenzie Deltaic System, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. The basin contains roughly 5 or 6 million cubic km of sediment. Three fourths or more of this volume generates low amplitude seismic reflections, interpreted to represent hemipelagic deposits, which contain lenses to extensive interbeds of moderate amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits.Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin is correlative with stratigraphic sequences in these areas that contain intervals of hydrocarbon source rocks. In addition, worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas windows. Structural, stratigraphic and combined structural and stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin, and at least one of these contains bright spots. However, deep water (to almost 4000 m), remoteness from harbors and markets, and thick accumulations of seasonal to permanent sea ice (until its possible removal by global warming later this century) will require the discovery of very large deposits for commercial success in most parts of Canada Basin. ?? 2011 Elsevier Ltd.

  2. Simultaneous electrodialytic removal of PAH, PCB, TBT and heavy metals from sediments

    DEFF Research Database (Denmark)

    Pedersen, Kristine B.; Lejon, Tore; Jensen, Pernille Erland

    2017-01-01

    with the need of different remedial actions for each pollutant. In this study, electrodialytic remediation (EDR) of sediments was found effective for simultaneous removal of heavy metals and organic pollutants for sediments from Arctic regions - Sisimiut in Greenland and Hammerfest in Norway. The influence...... was found to be important for the removal of heavy metals and TBT, while photolysis was significant for removal of PAH, PCB and TBT. In addition, dechlorination was found to be important for the removal of PCB. The highest removal efficiencies were found for heavy metals, TBT and PCB (>40%) and lower......Contaminated sediments are remediated in order to protect human health and the environment, with the additional benefit of using the treated sediments for other activities. Common for many polluted sediments is the contamination with several different pollutants, making remediation challenging...

  3. Widespread Anthropogenic Nitrogen in Northwestern Pacific Ocean Sediment.

    Science.gov (United States)

    Kim, Haryun; Lee, Kitack; Lim, Dhong-Il; Nam, Seung-Il; Kim, Tae-Wook; Yang, Jin-Yu T; Ko, Young Ho; Shin, Kyung-Hoon; Lee, Eunil

    2017-06-06

    Sediment samples from the East China and Yellow seas collected adjacent to continental China were found to have lower δ 15 N values (expressed as δ 15 N = [ 15 N: 14 N sample / 15 N: 14 N air - 1] × 1000‰; the sediment 15 N: 14 N ratio relative to the air nitrogen 15 N: 14 N ratio). In contrast, the Arctic sediments from the Chukchi Sea, the sampling region furthest from China, showed higher δ 15 N values (2-3‰ higher than those representing the East China and the Yellow sea sediments). Across the sites sampled, the levels of sediment δ 15 N increased with increasing distance from China, which is broadly consistent with the decreasing influence of anthropogenic nitrogen (N ANTH ) resulting from fossil fuel combustion and fertilizer use. We concluded that, of several processes, the input of N ANTH appears to be emerging as a new driver of change in the sediment δ 15 N value in marginal seas adjacent to China. The present results indicate that the effect of N ANTH has extended beyond the ocean water column into the deep sedimentary environment, presumably via biological assimilation of N ANTH followed by deposition. Further, the findings indicate that N ANTH is taking over from the conventional paradigm of nitrate flux from nitrate-rich deep water as the primary driver of biological export production in this region of the Pacific Ocean.

  4. Prediction of bedload sediment transport for heterogeneous sediments in shape

    Science.gov (United States)

    Durafour, Marine; Jarno, Armelle; Le Bot, Sophie; Lafite, Robert; Marin, François

    2015-04-01

    Key words: Particle shape, in-situ measurements, bedload transport, heterogeneous sediments Bedload sediment transport in the coastal area is a dynamic process mainly influenced by the type of hydrodynamic forcings involved (current and/or waves), the flow properties (velocity, viscosity, depth) and sediment heterogeneity (particle size, density, shape). Although particle shape is recognized to be a significant factor in the hydrodynamic behavior of grains, this parameter is not currently implemented in bedload transport formulations: firstly because the mechanisms of initiation of motion according to particle shape are still not fully understood, and secondly due to the difficulties in defining common shape parameters. In March 2011, a large panel of in-situ instruments was deployed on two sites in the Eastern English Channel, during the sea campaign MESFLUX11. Samples of the sediment cover available for transport are collected, during a slack period, per 2cm thick strata by divers and by using a Shipeck grab. Bedload discharges along a tidal cycle are also collected with a Delft Nile Sampler (DNS; Gaweesh and Van Rijn, 1992, 1994) on both sites. The first one is characterized by a sandy bed with a low size dispersion, while the other study area implies graded sediments from fine sands to granules. A detailed analysis of the data is performed to follow the evolution of in-situ bedload fluxes on the seabed for a single current. In-situ measurements are compared to existing formulations according to a single fraction approach, using the median diameter of the mixture, and a fractionwise approach, involving a discretization of the grading curve. Results emphasize the interest to oscillate between these two methods according to the dispersion in size of the site considered. The need to apply a hiding/exposure coefficient (Egiazaroff, 1965) and a hindrance factor (Kleinhans and Van Rijn, 2002) for size heterogeneous sediments is also clearly highlighted. A really good

  5. Hydrochemical Atlas of the Arctic Ocean (NODC Accession 0044630)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The present Hydrochemical Atlas of the Arctic Ocean is a description of hydrochemical conditions in the Arctic Ocean on the basis of a greater body of hydrochemical...

  6. A quantitative assessment of Arctic shipping in 2010–2014

    KAUST Repository

    Eguíluz, Victor M.

    2016-08-01

    Rapid loss of sea ice is opening up the Arctic Ocean to shipping, a practice that is forecasted to increase rapidly by 2050 when many models predict that the Arctic Ocean will largely be free of ice toward the end of summer. These forecasts carry considerable uncertainty because Arctic shipping was previously considered too sparse to allow for adequate validation. Here, we provide quantitative evidence that the extent of Arctic shipping in the period 2011–2014 is already significant and that it is concentrated (i) in the Norwegian and Barents Seas, and (ii) predominantly accessed via the Northeast and Northwest Passages. Thick ice along the forecasted direct trans-Arctic route was still present in 2014, preventing transit. Although Arctic shipping remains constrained by the extent of ice coverage, during every September, this coverage is at a minimum, allowing the highest levels of shipping activity. Access to Arctic resources, particularly fisheries, is the most important driver of Arctic shipping thus far.

  7. A quantitative assessment of Arctic shipping in 2010–2014

    KAUST Repository

    Eguí luz, Victor M.; Ferná ndez-Gracia, Juan; Irigoien, Xabier; Duarte, Carlos M.

    2016-01-01

    considerable uncertainty because Arctic shipping was previously considered too sparse to allow for adequate validation. Here, we provide quantitative evidence that the extent of Arctic shipping in the period 2011–2014 is already significant

  8. Greenland and the international politics of a changing arctic

    DEFF Research Database (Denmark)

    Greenland and the International Politics of a Changing Arctic examines the international politics of semi-independent Greenland in a changing and increasingly globalised Arctic. Without sovereign statehood, but with increased geopolitical importance, independent foreign policy ambitions......, and a solidified self-image as a trailblazer for Arctic indigenous peoples’ rights, Greenland is making its mark on the Arctic and is in turn affected – and empowered – by Arctic developments. The chapters in this collection analyse how a distinct Greenlandic foreign policy identity shapes political ends and means...... for regional change in the Arctic. This is the first comprehensive and interdisciplinary examination of Greenland’s international relations and how they are connected to wider Arctic politics. It will be essential reading for students and scholars interested in Arctic governance and security, international...

  9. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait.

    Directory of Open Access Journals (Sweden)

    Cecile Cathalot

    Full Text Available The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents. Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m, a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1 compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1. The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger

  10. The contribution of bank and surface sediments to fluvial sediment ...

    African Journals Online (AJOL)

    The contribution of bank and surface sediments to fluvial sediment transport of the Pra River. ... the relative contribution of surface and bank sediments to the fluvial sediment transport. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  11. Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum

    Science.gov (United States)

    Sluijs, A.; Schouten, S.; Pagani, M.; Woltering, M.; Brinkhuis, H.; Damste, J.S.S.; Dickens, G.R.; Huber, M.; Reichart, G.-J.; Stein, R.; Matthiessen, J.; Lourens, L.J.; Pedentchouk, N.; Backman, J.; Moran, K.; Clemens, S.; Cronin, T.; Eynaud, F.; Gattacceca, J.; Jakobsson, M.; Jordan, R.; Kaminski, M.; King, J.; Koc, N.; Martinez, N.C.; McInroy, D.; Moore, T.C.; O'Regan, M.; Onodera, J.; Palike, H.; Rea, B.; Rio, D.; Sakamoto, T.; Smith, D.C.; St John, K.E.K.; Suto, I.; Suzuki, N.; Takahashi, K.; Watanabe, M. E.; Yamamoto, M.

    2006-01-01

    The Palaeocene/Eocene thermal maximum, ???55 million years ago, was a brief period of widespread, extreme climatic warming, that was associated with massive atmospheric greenhouse gas input. Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. Here we identify the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence obtained during the Arctic Coring Expedition. We show that sea surface temperatures near the North Pole increased from ???18??C to over 23??C during this event. Such warm values imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming. At the same time, sea level rose while anoxic and euxinic conditions developed in the ocean's bottom waters and photic zone, respectively. Increasing temperature and sea level match expectations based on palaeoclimate model simulations, but the absolute polar temperatures that we derive before, during and after the event are more than 10??C warmer than those model-predicted. This suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms-perhaps polar stratospheric clouds or hurricane-induced ocean mixing-to amplify early Palaeogene polar temperatures. ?? 2006 Nature Publishing Group.

  12. Facets of Arctic energy accumulation based on observations and reanalyses 2000-2015.

    Science.gov (United States)

    Mayer, Michael; Haimberger, Leopold; Pietschnig, Marianne; Storto, Andrea

    2016-10-16

    Various observation- and reanalysis-based estimates of sea ice mass and ocean heat content trends imply that the energy imbalance of the Arctic climate system was similar [1.0 (0.9,1.2) Wm -2 ] to the global ocean average during the 2000-2015 period. Most of this extra heat warmed the ocean, and a comparatively small fraction went into sea ice melt. Poleward energy transports and radiation contributed to this energy increase at varying strengths. On a seasonal scale, stronger radiative energy input during summer associated with the ice-albedo feedback enhances seasonal oceanic heat uptake and sea ice melt. In return, lower sea ice extent and higher sea surface temperatures lead to enhanced heat release from the ocean during fall. This weakens meridional temperature gradients, consequently reducing atmospheric energy transports into the polar cap. The seasonal cycle of the Arctic energy budget is thus amplified, whereas the Arctic's long-term energy imbalance is close to the global mean.

  13. Intercontinental dispersal of giant thermophilic ants across the Arctic during early Eocene hyperthermals.

    Science.gov (United States)

    Archibald, S Bruce; Johnson, Kirk R; Mathewes, Rolf W; Greenwood, David R

    2011-12-22

    Early Eocene land bridges allowed numerous plant and animal species to cross between Europe and North America via the Arctic. While many species suited to prevailing cool Arctic climates would have been able to cross throughout much of this period, others would have found dispersal opportunities only during limited intervals when their requirements for higher temperatures were met. Here, we present Titanomyrma lubei gen. et sp. nov. from Wyoming, USA, a new giant (greater than 5 cm long) formiciine ant from the early Eocene (approx. 49.5 Ma) Green River Formation. We show that the extinct ant subfamily Formiciinae is only known from localities with an estimated mean annual temperature of about 20°C or greater, consistent with the tropical ranges of almost all of the largest living ant species. This is, to our knowledge, the first known formiciine of gigantic size in the Western Hemisphere and the first reported cross-Arctic dispersal by a thermophilic insect group. This implies intercontinental migration during one or more brief high-temperature episodes (hyperthermals) sometime between the latest Palaeocene establishment of intercontinental land connections and the presence of giant formiciines in Europe and North America by the early middle Eocene.

  14. Air-sea exchange fluxes of synthetic polycyclic musks in the North Sea and the Arctic.

    Science.gov (United States)

    Xie, Zhiyong; Ebinghaus, Ralf; Temme, Christian; Heemken, Olaf; Ruck, Wolfgang

    2007-08-15

    Synthetic polycyclic musk fragrances Galaxolide (HHCB) and Tonalide (AHTN) were measured simultaneously in air and seawater in the Arctic and the North Sea and in the rural air of northern Germany. Median concentrations of gas-phase HHCB and AHTN were 4 and 18 pg m(-3) in the Arctic, 28 and 18 pg m(-3) in the North Sea, and 71 and 21 pg m(-3) in northern Germany, respectively. Various ratios of HHCB/AHTN implied that HHCB is quickly removed by atmospheric degradation, while AHTN is relatively persistent in the atmosphere. Dissolved concentrations ranged from 12 to 2030 pg L(-1) for HHCB and from below the method detection limit (3 pg L(-1)) to 965 pg L(-1) for AHTN with median values of 59 and 23 pg L(-1), respectively. The medians of volatilization fluxes for HHCB and AHTN were 27.2 and 14.2 ng m(-2) day(-1) and the depositional fluxes were 5.9 and 3.3 ng m(-2) day(-1), respectively, indicating water-to-air volatilization is a significant process to eliminate HHCB and AHTN from the North Sea. In the Arctic, deposition fluxes dominated the air-sea gas exchange of HHCB and AHTN, suggesting atmospheric input controls the levels of HHCB and AHTN in the polar region.

  15. Does Reality Matter? Social and Science Bases of Public Beliefs about Arctic Change

    Science.gov (United States)

    Walker, D. A.; Schaefer, K. M.; Schaeffer, K. P.; Schaefer, K. M.; Hamilton, L.

    2015-12-01

    Surveys of public perceptions about trends in Arctic sea ice find that over two-thirds are aware of the multi-decade decrease. This awareness differs sharply across ideological and educational subgroups, however. It does not appear to shift in response to scientific and media discussion following a September with unusually low (2012) or somewhat higher (2013) sea ice extent. Other perceptions about Arctic change, such as impacts on mid-latitude weather, follow similar patterns with sharp ideological difference and limited response to external events, including science reports. On the other hand, public accuracy on basic factual questions that do not by themselves imply directional change (such as location of the North Pole) may be very low, and among some subgroups accurate knowledge shows an oddly negative correlation with self-confidence about understanding of climate change. These results from 13 surveys over 2011-2015 suggest that biased assimilation filters the acceptance of information about Arctic change, with implications for science communication.

  16. Intercontinental dispersal of giant thermophilic ants across the Arctic during early Eocene hyperthermals

    Science.gov (United States)

    Archibald, S. Bruce; Johnson, Kirk R.; Mathewes, Rolf W.; Greenwood, David R.

    2011-01-01

    Early Eocene land bridges allowed numerous plant and animal species to cross between Europe and North America via the Arctic. While many species suited to prevailing cool Arctic climates would have been able to cross throughout much of this period, others would have found dispersal opportunities only during limited intervals when their requirements for higher temperatures were met. Here, we present Titanomyrma lubei gen. et sp. nov. from Wyoming, USA, a new giant (greater than 5 cm long) formiciine ant from the early Eocene (approx. 49.5 Ma) Green River Formation. We show that the extinct ant subfamily Formiciinae is only known from localities with an estimated mean annual temperature of about 20°C or greater, consistent with the tropical ranges of almost all of the largest living ant species. This is, to our knowledge, the first known formiciine of gigantic size in the Western Hemisphere and the first reported cross-Arctic dispersal by a thermophilic insect group. This implies intercontinental migration during one or more brief high-temperature episodes (hyperthermals) sometime between the latest Palaeocene establishment of intercontinental land connections and the presence of giant formiciines in Europe and North America by the early middle Eocene. PMID:21543354

  17. Changing geo-political realities in the Arctic region

    DEFF Research Database (Denmark)

    Sørensen, Camilla T. N.

    2014-01-01

    This article analyzes and discusses how Denmark seeks to manage the changing geopolitical realities in the Arctic region specifically focusing on how Denmark seeks to manage its relations with China in the Arctic region.......This article analyzes and discusses how Denmark seeks to manage the changing geopolitical realities in the Arctic region specifically focusing on how Denmark seeks to manage its relations with China in the Arctic region....

  18. The role of the Arctic in future global petroleum supply

    OpenAIRE

    Lars Lindholt; Solveig Glomsrød

    2011-01-01

    The Arctic has a substantial share of global petroleum resources, but at higher costs than in most other petroleum provinces. Arctic states and petroleum companies are carefully considering the potential for future extraction in the Arctic. This paper studies the oil and gas supply from 6 arctic regions during 2010-2050 along with global economic growth and different assumptions regarding petroleum prices and resource endowments. Supply is calculated based on a global model of oil and gas mar...

  19. Airborne contaminants in the Arctic: What we need to know

    International Nuclear Information System (INIS)

    Landers, D.H.; Bangay, G.; Sisula, H.; Colborn, T.; Liljelund, L.E.

    1994-01-01

    Arctic contaminant research is expensive and current international resources are restricted. It is incumbent upon current and future arctic research programs to focus efforts where the greatest and most relevant information can be gained. This paper is an attempt to help guide future work to focus on the most pressing information needs. Several summary points are related to environmental research in the Arctic; some may also relate to environmental research outside the Arctic

  20. Size Does Matter: Implied Object Size is Mentally Simulated During Language Comprehension

    NARCIS (Netherlands)

    de Koning, Bjorn B.; Wassenburg, Stephanie I.; Bos, Lisanne T.; Van der Schoot, Menno

    2017-01-01

    Embodied theories of language comprehension propose that readers construct a mental simulation of described objects that contains perceptual characteristics of their real-world referents. The present study is the first to investigate directly whether implied object size is mentally simulated during

  1. The Effect of Implied Performer Age and Group Membership on Evaluations of Music Performances

    Science.gov (United States)

    Harrington, Ann M.

    2018-01-01

    This study examined the effects of implied performer age and group membership on listeners' evaluations of music performances. Undergraduate music majors (n = 23), nonmusic majors (n = 17), and members of a New Horizons ensemble (n = 16) were presented with six 30-second excerpts of concert band performances. Excerpts were presented to all…

  2. Covariance of time-ordered products implies local commutativity of fields

    International Nuclear Information System (INIS)

    Greenberg, O.W.

    2006-01-01

    We formulate Lorentz covariance of a quantum field theory in terms of covariance of time-ordered products (or other Green's functions). This formulation of Lorentz covariance implies spacelike local commutativity or anticommutativity of fields, sometimes called microscopic causality or microcausality. With this formulation microcausality does not have to be taken as a separate assumption

  3. Latent Integrated Stochastic Volatility, Realized Volatility, and Implied Volatility: A State Space Approach

    DEFF Research Database (Denmark)

    Bach, Christian; Christensen, Bent Jesper

    process is downward biased. Implied volatility performs better than any of the alternative realized measures when forecasting future integrated volatility. The results are largely similar across the stock market (S&P 500), bond market (30-year U.S. T-bond), and foreign currency exchange market ($/£ )....

  4. No, Virginia, It's Not True What They Say About Publicity's "Implied Third-Party Endorsement" Effect.

    Science.gov (United States)

    Hallahan, Kirk

    1999-01-01

    Re-examines "implied third-party endorsement" as an explanation of publicity's effectiveness. Argues that any effect involves inferences by audience members who use biased processing that favors news and disfavors advertising. Suggests that the presentation of information as news is not necessarily perceived by audiences as an…

  5. Implied Volatility of Interest Rate Options: An Empirical Investigation of the Market Model

    DEFF Research Database (Denmark)

    Christiansen, Charlotte; Hansen, Charlotte Strunk

    2002-01-01

    We analyze the empirical properties of the volatility implied in options on the 13-week US Treasury bill rate. These options have not been studied previously. It is shown that a European style put option on the interest rate is equivalent to a call option on a zero-coupon bond. We apply the LIBOR...

  6. Level Shifts in Volatility and the Implied-Realized Volatility Relation

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; de Magistris, Paolo Santucci

    We propose a simple model in which realized stock market return volatility and implied volatility backed out of option prices are subject to common level shifts corresponding to movements between bull and bear markets. The model is estimated using the Kalman filter in a generalization to the mult......We propose a simple model in which realized stock market return volatility and implied volatility backed out of option prices are subject to common level shifts corresponding to movements between bull and bear markets. The model is estimated using the Kalman filter in a generalization...... to the multivariate case of the univariate level shift technique by Lu and Perron (2008). An application to the S&P500 index and a simulation experiment show that the recently documented empirical properties of strong persistence in volatility and forecastability of future realized volatility from current implied...... volatility, which have been interpreted as long memory (or fractional integration) in volatility and fractional cointegration between implied and realized volatility, are accounted for by occasional common level shifts....

  7. Asymptotic Expansions of the Lognormal Implied Volatility : A Model Free Approach

    OpenAIRE

    Cyril Grunspan

    2011-01-01

    We invert the Black-Scholes formula. We consider the cases low strike, large strike, short maturity and large maturity. We give explicitly the first 5 terms of the expansions. A method to compute all the terms by induction is also given. At the money, we have a closed form formula for implied lognormal volatility in terms of a power series in call price.

  8. Aplikasi Algoritma Biseksi dan Newton-Raphson dalam Menaksir Nilai Volatilitas Implied

    Directory of Open Access Journals (Sweden)

    Komang Dharmawan

    2012-11-01

    Full Text Available Volatilitas adalah suatu besaran yang mengukuran seberapa jauh suatu harga sahambergerak dalam suatu periode tertentu dapat juga diartikan sebagai persentase simpanganbaku dari perubahan harga harian suatu saham. Menurut teori yang dikembangkan oleh Black-Scholes in 1973, semua harga opsi dengan ’underlying asset’ dan waktu jatuh tempo yang samatetapi memiliki nilai exercise yang berbeda akan memiliki nilai volatilitas implied yang sama.Model Black-Scholes dapat dipakai mengestimasi nilai volatilitas implied dari suatu sahamdengan mencari sulusi numerik dari persamaan invers dari model Black-Scholes. Makalah inimendemonstrasikan bagaimana menghitung nilai volatilitas implied suatu saham dengan mengasumsikanbahwa model Black-schole adalah benar dan suatu kontrak opsi dengan denganumur kontrak yang sama akan memiliki harga yang sama. Menggunakan data harga opsi SonyCorporation (SNE, Cisco Systems, Inc (CSCO, dan Canon, Inc (CNJ diperoleh bahwa, ImpliedVolatility memberikan harga yang lebih murah dibandingkan dengan harga opsi darivolatilitas yang dihitung dari data historis. Selain itu, dari hasil iterasi yang diperoleh, metodeNewton-Raphson lebih cepat konvergen dibandingkan dengan metode Bisection.

  9. Tundra Rehabilitation in Alaska's Arctic

    Science.gov (United States)

    Lynn, L. A.

    2012-12-01

    Oil exploration in Alaska's Arctic has been conducted for more than 40 years, resulting in over 3,640 ha of gravel fill placed for roads, pads, and airstrips to support the industry. Likewise, tundra disturbance from burying power lines and by tundra vehicle travel are also common. Rehabilitation of disturbed sites began around 2002, with well over 150 ha that has been previously treated or is currently being rehabilitated. Two primary goals of rehabilitation efforts have been 1) revegetation by indigenous species, and 2) limiting thermokarst. Early efforts were concerned that removing gravel and having exposed bare ground would lead to extensive subsidence and eolian erosion. Native grass cultivars (e.g. Poa glauca, Arctagrostis latifolia, and Festuca rubra) were seeded to create vegetation cover quickly with the expectation that these grasses would survive only temporarily. The root masses and leaf litter were also expected to trap indigenous seed to enhance natural recolonization by indigenous plants. Due to the remote location of these sites, many of which are only accessible by helicopter, most are visited only two to three times following cultivation treatments, providing a limited data pool. At many sites, the total live seeded grass cover declined about 15% over the first 5¬-6 years (from around 30% to 15% cover), while total live indigenous vascular cover increased from no or trace cover to an average of 10% cover in that time. Cover of indigenous vascular plants at sites that were not seeded with native grass cultivars averaged just less than 10% after 10 years, showing no appreciable difference between the two approaches. Final surface elevations at the sites affect local hydrology and soil moisture. Other factors that influence the success of vegetation cover are proximity to the Arctic coast (salt effects), depth of remaining gravel, and changes in characteristics of the near-surface soil. Further development of rehabilitation techniques and the

  10. Analysis of the origin of Aufeis feed-water on the arctic slope of Alaska

    Science.gov (United States)

    Hall, D. K.; Roswell, C. (Principal Investigator)

    1980-01-01

    The origin of water feeding large aufeis fields (overflow river ice) on the Arctic Slope of Alaska is analyzed. Field measurements of two large aufeis fields on the eastern Arctic Slope were taken during July of 1978 and 1979. Measurements of aufeis extent and distribution were made using LANDSAT Multispectral Scanner Subsystem (MSS) satellite data from 1973 through 1979. In addition, ice cores were analyzed in the laboratory. Results of the field and laboratory studies indicate that the water derived from aufeis melt water has a chemical composition different from the adjacent upstream river water. Large aufeis fields are found in association with springs and faults thus indicating a subterranean origin of the feed water. In addition, the maximum extent of large aufeis fields was not found to follow meteorological patterns which would only be expected if the origin of the feed water were local. It is concluded that extent of large aufeis in a given river channel on the Arctic Slope is controlled by discharge from reservoirs of groundwater. It seems probable that precipitation passes into limestone aquifers in the Brooks Range, through an interconnecting system of subterranean fractures in calcareous rocks and ultimately discharges into alluvial sediments on the coastal plain to form aufeis. It is speculated that only small aufeis patches are affected by local meteorological parameters in the months just prior to aufeis formation.

  11. Greenhouse gas emissions from diverse Arctic Alaskan lakes are dominated by young carbon

    Science.gov (United States)

    Elder, Clayton D.; Xu, Xiaomei; Walker, Jennifer; Schnell, Jordan L.; Hinkel, Kenneth M.; Townsend-Small, Amy; Arp, Christopher D.; Pohlman, John; Gaglioti, Benjamin V.; Czimzik, Claudia I.

    2018-01-01

    Climate-sensitive Arctic lakes have been identified as conduits for ancient permafrost-carbon (C) emissions and as such accelerate warming. However, the environmental factors that control emission pathways and their sources are unclear; this complicates upscaling, forecasting and climate-impact-assessment efforts. Here we show that current whole-lake CH4 and CO2 emissions from widespread lakes in Arctic Alaska primarily originate from organic matter fixed within the past 3–4 millennia (modern to 3,300 ± 70 years before the present), and not from Pleistocene permafrost C. Furthermore, almost 100% of the annual diffusive C flux is emitted as CO2. Although the lakes mostly processed younger C (89 ± 3% of total C emissions), minor contributions from ancient C sources were two times greater in fine-textured versus coarse-textured Pleistocene sediments, which emphasizes the importance of the underlying geological substrate in current and future emissions. This spatially extensive survey considered the environmental and temporal variability necessary to monitor and forecast the fate of ancient permafrost C as Arctic warming progresses.

  12. Greenhouse gas emissions from diverse Arctic Alaskan lakes are dominated by young carbon

    Science.gov (United States)

    Elder, Clayton D.; Xu, Xiaomei; Walker, Jennifer; Schnell, Jordan L.; Hinkel, Kenneth M.; Townsend-Small, Amy; Arp, Christopher D.; Pohlman, John W.; Gaglioti, Benjamin V.; Czimczik, Claudia I.

    2018-01-01

    Climate-sensitive Arctic lakes have been identified as conduits for ancient permafrost-carbon (C) emissions and as such accelerate warming. However, the environmental factors that control emission pathways and their sources are unclear; this complicates upscaling, forecasting and climate-impact-assessment efforts. Here we show that current whole-lake CH4 and CO2 emissions from widespread lakes in Arctic Alaska primarily originate from organic matter fixed within the past 3-4 millennia (modern to 3,300 ± 70 years before the present), and not from Pleistocene permafrost C. Furthermore, almost 100% of the annual diffusive C flux is emitted as CO2. Although the lakes mostly processed younger C (89 ± 3% of total C emissions), minor contributions from ancient C sources were two times greater in fine-textured versus coarse-textured Pleistocene sediments, which emphasizes the importance of the underlying geological substrate in current and future emissions. This spatially extensive survey considered the environmental and temporal variability necessary to monitor and forecast the fate of ancient permafrost C as Arctic warming progresses.

  13. Pliocene cooling enhanced by flow of low-salinity Bering Sea water to the Arctic Ocean.

    Science.gov (United States)

    Horikawa, Keiji; Martin, Ellen E; Basak, Chandranath; Onodera, Jonaotaro; Seki, Osamu; Sakamoto, Tatsuhiko; Ikehara, Minoru; Sakai, Saburo; Kawamura, Kimitaka

    2015-06-29

    Warming of high northern latitudes in the Pliocene (5.33-2.58 Myr ago) has been linked to the closure of the Central American Seaway and intensification of North Atlantic Deep Water. Subsequent cooling in the late Pliocene may be related to the effects of freshwater input from the Arctic Ocean via the Bering Strait, disrupting North Atlantic Deep Water formation and enhancing sea ice formation. However, the timing of Arctic freshening has not been defined. Here we present neodymium and lead isotope records of detrital sediment from the Bering Sea for the past 4.3 million years. Isotopic data suggest the presence of Alaskan glaciers as far back as 4.2 Myr ago, while diatom and C37:4 alkenone records show a long-term trend towards colder and fresher water in the Bering Sea beginning with the M2 glaciation (3.3 Myr ago). We argue that the introduction of low-salinity Bering Sea water to the Arctic Ocean by 3.3 Myr ago preconditioned the climate system for global cooling.

  14. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  15. Center for Contaminated Sediments

    Data.gov (United States)

    Federal Laboratory Consortium — The U.S. Army Corps of Engineers Center for Contaminated Sediments serves as a clearinghouse for technology and expertise concerned with contaminated sediments. The...

  16. Geochemistry of sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.

    Considering the potential of elemental data in marine sediments as diagnostic tools of various geological and oceanographic processes, sediment geochemical data from the Indian Ocean region has been reviewed in this article. Emphasis is laid...

  17. Indicators: Sediment Enzymes

    Science.gov (United States)

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  18. Electrodialytic remediation of sediments

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland

    Sediments of harbors and freshwaters are regularly dredged for various reasons: maintenance of navigational depths, recovery of recreational locations, and even environmental recovery. In the past, sediments dredged from harbors have been dumped at sea, however, environmental regulations now, in ...

  19. Future-Proofing Japan’s Interests in the Arctic

    DEFF Research Database (Denmark)

    Tonami, Aki

    2014-01-01

    credentials Japan has to be involved in the leading Arctic forum. However, a closer look at its engagement in the Arctic indicates that Japan has genuine interests in political, economic, and environmental developments there. This essay examines Japan’s interests in the Arctic, its new role as an observer...

  20. Romantic notions about the arctic must include indigenous rights

    DEFF Research Database (Denmark)

    Burke, Danita Catherine

    2017-01-01

    The Arctic plays a big role in Canada's national identity. But as Canada's relationship with the region evolves, the interests of Indigenous peoples must be better represented. This article summarizes the research in my book 'International Disputes and Cultural Ideas in the Canadian Arctic: Arctic...