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Sample records for production determine arctic

  1. Latitudinal gradients in sea ice and primary production determine Arctic seabird colony size in Greenland

    PubMed Central

    Laidre, Kristin L; Heide-Jørgensen, Mads Peter; Nyeland, Jens; Mosbech, Anders; Boertmann, David

    2008-01-01

    Sea ice loss will indirectly alter energy transfer through the pelagic food web and ultimately impact apex predators. We quantified spring-time trends in sea ice recession around each of 46 thick-billed murre (Uria lomvia) colonies in west Greenland across 20° of latitude and investigated the magnitude and timing of the associated spring-time primary production. A geographical information system was used to extract satellite-based observations of sea ice concentration from the Nimbus-7 scanning multichannel microwave radiometer (SMMR, 1979–1987) and the Defence Meteorological Satellite Programs Special Sensor Microwave/Imager (SSMI, 1987–2004), and satellite-based observations of chlorophyll a from the moderate resolution imaging spectroradiometer (MODIS: EOS-Terra satellite) in weekly intervals in circular buffers around each colony site (150 km in radius). Rapid recession of high Arctic seasonal ice cover created a temporally predictable primary production bloom and associated trophic cascade in water gradually exposed to solar radiation. This pattern was largely absent from lower latitudes where little to no sea ice resulted in a temporally variable primary production bloom driven by nutrient cycling and upwelling uncoupled to ice. The relationship between the rate and variability of sea ice recession and colony size of thick-billed murres shows that periodical confinement of the trophic cascade at high latitudes determines the carrying capacity for Arctic seabirds during the breeding period. PMID:18713716

  2. Determination of Atmospheric Properties Over Arctic Polynyas

    NASA Astrophysics Data System (ADS)

    Key, E. L.; Minnett, P. J.

    2004-12-01

    Due to the relatively sparse in situ and satellite-derived data collection at polar latitudes, model analyses rely primarily on coastal weather station time series for atmospheric initialization. Values from these sites are extrapolated over adjacent marine environments, including nearby polynyas - areas of open water within the ice pack. However, most weather stations are topographically-shadowed or under the influence of katabatic drainage, so that measurements are localized and unrepresentative of the area covered by large-scale analytical grids. Moreover, the surface fluxes over land are not comparable to those in a polynya environment, where there are increases heat and moisture exchange across the oceanic interface, often leading to the formation of convective cloud at the downwind polynya edge. To determine the best accuracy of analyzed moisture and temperature profiles, independent, ship-based radiosondes collected offshore of the flat, ponded, coastal plain at Barrow, Alaska are compared against upper air observations from a weather station, the ARM (Atmospheric Radiation Measurement) North Slope of Alaska-Adjacent Arctic Ocean site, MODIS retrievals, and the NCEP Final Analysis (FNL) 1-degree moisture and temperature profiles. While the atmospheric temperature structure agrees well amongst the five data sets, the analyzed and retrieved humidity profiles do not capture the boundary layer moisture, and are in fact drier than upper air observations despite a known "dry bias" in radiosonde data. Comparisons of surface fields are limited to ship-model match-ups and largely reflect limitations of coarse model resolution.

  3. Environmental and petroleum resource conflicts: a simulation model to determine the benefits of petroleum production in the Arctic National Wildlife Refuge, Alaska

    SciTech Connect

    Goerold, W.T.

    1987-01-01

    The Arctic National Wildlife Refuge (ANWR), located on the Alaska North Slope, is believed to contain high petroleum production potential. This region also has outstanding wildlife and wilderness values. Currently ANWR is closed to oil and gas leasing. However, Congress is considering an Interior Department recommendation to open a portion of ANWR to oil and gas production. Environmentalists maintain that petroleum exploration and development will have severe environmental impacts. A draft study by the Interior Department reports values that are used to generate an expected present value of the net economic benefits of petroleum development in ANWR of $2.98 billion. Alternatively, using updated oil price projections and revised tax and financial assumptions, the Arctic National Wildlife Refuge Financial Analysis Simulation Model (AFAM) projects the expected present value of net economic benefits of oil production at between $0.32 and $1.39 billion. AFAM results indicate that, within most drilling cost scenarios, oil producers would earn an aftertax profit in 100% of the simulation trials. However, in a high-cost drilling scenario, AFAM projects aftertax losses to oil producers in 45% of the simulation trials. Although the Interior Department does not report a range of net economic benefits from oil development of ANWR, AFAM indicates that the distribution of net economic benefits across all scenarios is positively skewed. Net economic benefits from oil development range from $0 to $4.75 billion with a greater probability of benefits closer to the lower value. Decision makers considering whether or not to open ANWR to petroleum development can use these values to judge if the economic benefits outweigh the projected negative wilderness and wildlife impacts. 10 references, 9 figures, 6 tables.

  4. Caisson shield for arctic offshore production platform

    SciTech Connect

    Clinton, J. D.; Reusswig, G. H.

    1985-03-12

    A caisson shield for the protection of an offshore production platform and, more particularly, a caisson shield for use in an arctic environment for the protection of the offshore structure in iceberg-infested waters which is capable of absorbing the destructive forces of an impact produced by a large iceberg. The caisson shield consists of an essentially annular concrete structure encircling at least the submerged support section of the offshore production platform including vertically upstanding concentrically spaced, annular side walls, a horizontal slab base resting on the marine bottom on which the side walls are supported, and a slab top supported on the side walls, and including annularly spaced internal radial partition walls whereby the entire overall caisson shield structure provides a generally toroidal configuration incorporating a plurality of closed compartments. In one embodiment of the invention, located along the outer annular wall is a plurality of arcuate wall sections forming a series of arches and enclosed compartments between each arcuate wall section and the outer annular wall, which impart a ''scallop-like'' configuration to the outer circumference of the caisson shield. The ''scallop-like'' outer walls are capable of resisting and absorbing extremely high ice loads by being adapted to progressively crush the leading edge of an impacting iceberg and to thereby minimize the crush of the iceberg against the caisson shield before coming to rest against the shield.

  5. Future Arctic Primary Productivity from CMIP5 Simulations: Uncertain Outcome, but Consistent Mechanisms

    NASA Astrophysics Data System (ADS)

    Vancoppenolle, Martin; Bopp, Laurent; Madec, Gurvan; Dunne, John; Ilyina, Tatiana; Halloran, Paul; Steiner, Nadja

    2013-04-01

    Net primary production (PP) in the Arctic should increase over this century, due to sea ice retreat, inducing an increase in available light, but could decrease if nitrate renewal is insufficient. Here, simulations performed with 11 Earth System Models from the CMIP5 exercise, covering 1900-2100, are analyzed using Arctic PP, surface nitrate and sea ice concentrations. Whereas the mean model well simulates Arctic-integrated PP at 511 TgC/yr for 1998-2005 and projects a 58 TgC/yr increase by 2080-2099, models neither agree on what limits PP today, nor on the sign of future PP change. However, the same mechanisms operate in all models. First, both sea ice and nitrate decrease over the 21st century. Depending on the model, the strengthening nitrate stress is sufficient to overcome the effect of light increase. The inter-model spread stems from present nitrate stocks, poorly constrained by observations and characterized by an inter-model uncertainty of >50% of the mean. Second, virtually all models agree in the open ocean zones on more spatially-integrated PP and less PP per unit area. Where models disagree is the sea ice zone, where a subtle balance between light and nutrient limitations determines the change in productivity. Hence, it is argued that reducing uncertainty on present Arctic nitrate would render Arctic PP projections much more consistent. That is definitely required to understand the impact of climate change on the Arctic food webs and carbon cycle.

  6. 76 FR 5236 - Culturally Significant Objects Imported for Exhibition Determinations: “Upside Down Arctic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition Determinations: ``Upside Down Arctic Realities... Down Arctic Realities,'' imported from abroad for temporary exhibition within the United States, are...

  7. Ultraviolet radiation enhances Arctic net plankton community production

    NASA Astrophysics Data System (ADS)

    Garcia-Corral, Lara S.; Agustí, Susana; Regaudie-de-Gioux, Aurore; Iuculano, Francesca; Carrillo-de-Albornoz, Paloma; Wassmann, Paul; Duarte, Carlos M.

    2014-08-01

    In this study we report the response of net community production (NCP) of plankton communities in the Arctic surface waters exposure to natural ultraviolet radiation (UVR) conditions. A possible bias in previous measurements performed using borosilicate glass bottles (opaque to most UVR) can underestimate NCP. Here we show that 77% of the sampled communities suffer, on average, 38.5% of net increase in NCP when exposed to natural UV-B condition, relative to values when UV-B radiation is excluded. UV-B tends to shift communities toward autotrophy, with the most autotrophic communities responding the strongest. This is likely explained by the inhibition of bacterial respiration during the continuous day period of the Arctic summer, corroborated by experiments where bacterial production influenced by UV-B directly affect NCP. Whereas Arctic warming is expected to lead to lower NCP, our results show that increased UV-B radiation may partially compensate this negative effect in surface waters.

  8. Seasonality of primary and secondary production in an Arctic river

    NASA Astrophysics Data System (ADS)

    Kendrick, M.; Huryn, A.; Deegan, L.

    2011-12-01

    Rivers and streams that freeze solid for 8-9 months each year provide excellent examples of the extreme seasonality of arctic habitats. The communities of organisms inhabiting these rivers must complete growth and development during summer, resulting in a rapid ramp-up and down of production over the short ice-free period. The effects of recent shifts in the timing of the spring thaw and autumn freeze-up on the duration and pattern of the period of active production are poorly understood. We are currently investigating: 1) the response of the biotic community of the Kuparuk River (Arctic Alaska) to shifts in the seasonality of the ice-free period, and 2) the community response to increases in phosphorous (P) supply anticipated as the volume of the permafrost active-layer increases in response to climate warming. Here algal production supports a 2-tier web of consumers. We tracked primary and secondary production from the spring thaw through mid-August in a reference reach and one receiving low-level P fertilization. Gross primary production/community respiration (GPP/R) ratios for both reaches were increasing through mid-July, with higher GPP/R in response to the P addition. Understanding the degree of synchrony between primary and secondary production in this Arctic river system will enhance further understanding of how shifts in seasonality affect trophic dynamics.

  9. Warming increases methylmercury production in an Arctic soil.

    PubMed

    Yang, Ziming; Fang, Wei; Lu, Xia; Sheng, Guo-Ping; Graham, David E; Liang, Liyuan; Wullschleger, Stan D; Gu, Baohua

    2016-07-01

    Rapid temperature rise in Arctic permafrost impacts not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) toxin that can endanger humans, as well as wildlife in terrestrial and aquatic ecosystems. Currently little is known concerning the effects of rapid permafrost thaw on microbial methylation and how SOC degradation is coupled to MeHg biosynthesis. Here we describe the effects of warming on MeHg production in an Arctic soil during an 8-month anoxic incubation experiment. Net MeHg production increased >10 fold in both organic- and mineral-rich soil layers at warmer (8 °C) than colder (-2 °C) temperatures. The type and availability of labile SOC, such as reducing sugars and ethanol, were particularly important in fueling the rapid initial biosynthesis of MeHg. Freshly amended mercury was more readily methylated than preexisting mercury in the soil. Additionally, positive correlations between mercury methylation and methane and ferrous ion production indicate linkages between SOC degradation and MeHg production. These results show that climate warming and permafrost thaw could potentially enhance MeHg production by an order of magnitude, impacting Arctic terrestrial and aquatic ecosystems by increased exposure to mercury through bioaccumulation and biomagnification in the food web. PMID:27131808

  10. Warming increases methylmercury production in an Arctic soil

    DOE PAGESBeta

    Yang, Ziming; Fang, Wei; Lu, Xia; Sheng, Guo-Ping; Graham, David E.; Liang, Liyuan; Wullschleger, Stan D.; Gu, Baohua

    2016-04-29

    The rapid temperature rise in Arctic permafrost concerns not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) that may endanger humans, as well as wildlife in terrestrial, aquatic, and marine ecosystems. Decomposition of SOC provides an energy source for microbial methylation, although little is known how rapid permafrost thaw affects Hg methylation and how SOC degradation is coupled to MeHg biosynthesis. We describe rates of MeHg production in Arctic soils from an 8-month warming microcosm experiment under anoxic conditions. MeHg production increased >10 fold in both organic-more » and the mineral-rich soil layers at a warmer temperature (8 C) compared to a sub-zero temperature ( 2 C). MeHg production was positively correlated to methane and ferrous ion concentrations, suggesting that Hg methylation is coupled with methanogenesis and iron reduction. Labile SOC, such as reducing sugars and alcohol, were particularly effective in fueling the initial rapid biosynthesis of MeHg. In freshly amended Hg we found that there was more bioavailable than existing Hg in the mineral soil. Finally, the data indicate that climate warming and permafrost thaw could greatly enhance MeHg production, thereby impacting Arctic aquatic and marine ecosystems through biomagnification in the food web.« less

  11. Changing climate increases biological productivity in the Arctic

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-11-01

    Climate change is leading to increased biological productivity in the coastal Arctic. As ice melts and recedes far from land, winds interact with open waters to increase the upwelling of nutrient-rich deep water and stimulate biological productivity. Tremblay et al. quantified these changes using remote sensing and in situ observations in the coastal Beaufort Sea. They found that ice ablation and the combination of increased upwelling and greater light penetration into the water column during fall 2007 and summer 2008 increased the production of ice algae, phytoplankton, and zooplankton by 2-6 times. (Geophysical Research Letters, doi:10.1029/2011GL048825, 2011)

  12. Spring Snow Depth on Arctic Sea Ice using the IceBridge Snow Depth Product (Invited)

    NASA Astrophysics Data System (ADS)

    Webster, M.; Rigor, I. G.; Nghiem, S. V.; Kurtz, N. T.; Farrell, S. L.

    2013-12-01

    Snow has dual roles in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from colder air temperatures, slowing its growth. From spring into summer, the albedo of snow determines how much insolation is transmitted through the sea ice and into the underlying ocean, ultimately impacting the progression of the summer ice melt. Knowing the snow thickness and distribution are essential for understanding and modeling sea ice thermodynamics and the surface heat budget. Therefore, an accurate assessment of the snow cover is necessary for identifying its impacts in the changing Arctic. This study assesses springtime snow conditions on Arctic sea ice using airborne snow thickness measurements from Operation IceBridge (2009-2012). The 2012 data were validated with coordinated in situ measurements taken in March 2012 during the BRomine, Ozone, and Mercury EXperiment field campaign. We find a statistically significant correlation coefficient of 0.59 and RMS error of 5.8 cm. The comparison between the IceBridge snow thickness product and the 1937, 1954-1991 Soviet drifting ice station data suggests that the snow cover has thinned by 33% in the western Arctic and 44% in the Beaufort and Chukchi Seas. A rudimentary estimation shows that a thinner snow cover in the Beaufort and Chukchi Seas translates to a mid-December surface heat flux as high as 81 W/m2 compared to 32 W/m2. The relationship between the 2009-2012 thinner snow depth distribution and later sea ice freeze-up is statistically significant, with a correlation coefficient of 0.59. These results may help us better understand the surface energy budget in the changing Arctic, and may improve our ability to predict the future state of the sea ice cover.

  13. Melt ponds on Arctic sea ice determined from MODIS satellite data using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Rösel, A.; Kaleschke, L.; Birnbaum, G.

    2012-04-01

    Melt ponds on sea ice strongly reduce the surface albedo and accelerate the decay of Arctic sea ice. Due to different spectral properties of snow, ice, and water, the fractional coverage of these distinct surface types can be derived from multispectral sensors like the Moderate Resolution Image Spectroradiometer (MODIS) using a spectral unmixing algorithm. The unmixing was implemented using a multilayer perceptron to reduce computational costs. Arctic-wide melt pond fractions and sea ice concentrations are derived from the level 3 MODIS surface reflectance product. The validation of the MODIS melt pond data set was conducted with aerial photos from the MELTEX campaign 2008 in the Beaufort Sea, data sets from the National Snow and Ice Data Center (NSIDC) for 2000 and 2001 from four sites spread over the entire Arctic, and with ship observations from the trans-Arctic HOTRAX cruise in 2005. The root-mean-square errors range from 3.8 % for the comparison with HOTRAX data, over 10.7 % for the comparison with NSIDC data, to 10.3 % and 11.4 % for the comparison with MELTEX data, with coefficient of determination ranging from R2=0.28 to R2=0.45. The mean annual cycle of the melt pond fraction per grid cell for the entire Arctic shows a strong increase in June, reaching a maximum of 15 % by the end of June. The zonal mean of melt pond fractions indicates a dependence of the temporal development of melt ponds on the geographical latitude, and has its maximum in mid-July at latitudes between 80° and 88° N. Furthermore, the MODIS results are used to estimate the influence of melt ponds on retrievals of sea ice concentrations from passive microwave data. Results from a case study comparing sea ice concentrations from ARTIST Sea Ice-, NASA Team 2-, and Bootstrap-algorithms with MODIS sea ice concentrations indicate an underestimation of around 40 % for sea ice concentrations retrieved with microwave algorithms.

  14. Labile carbon concentrations are strongly linked to plant production in Arctic tussock tundra soils

    NASA Astrophysics Data System (ADS)

    Darrouzet-Nardi, A.; Weintraub, M. N.; Euskirchen, E. S.; Steltzer, H.; Sullivan, P.

    2013-12-01

    The exchange of carbon and nutrients between plants and microbes is a key determinant of carbon balance in Arctic soils. Microbes rely on labile plant carbon for the energy they need to produce enzymes that can release nutrients and less energetically favorable carbon from soil organic matter. One of the main mechanisms of carbon transfer is rhizodeposition, the exudation of labile plant carbon such as sugars from roots into the rhizosphere. Despite the importance of this flow of energy and materials from plants to microbes, there have been few attempts to quantify labile carbon pools or fluxes in Arctic soils. To improve our knowledge of labile carbon dynamics in Arctic soils, we address two basic questions: (1) What are the seasonal patterns of labile carbon concentrations? and (2) How do seasonal patterns in labile carbon correlate with plant production, microbial biomass, and soil nutrients? We measured concentrations of total reducing sugars (TRS) in the soil solution of moist acidic tussock tundra on 28 dates during the 2012 growing season in 20 plots of an early snowmelt × warming experiment. We evaluated these total reducing sugar concentrations in the context of eddy flux carbon exchange data, plant NDVI, total dissolved carbon in soils, microbial biomass, and soil nutrients. Though we did not see treatment effects of the snowmelt × warming experiment, we did observe a clear seasonal pattern in TRS concentrations in which they started low at the time of thaw, then built to a maximum value around the time of peak plant physiology in July, followed by a decline as plants senesced. We observed a clear correlation between TRS and gross primary production (GPP). NDVI values also increased with TRS concentrations during the first half of the season and then leveled off as TRS began its decline. These relationships were in contrast to labile N concentrations, which remained at low concentrations all season. Our data suggest that rhizodeposition of labile carbon

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

    NASA Astrophysics Data System (ADS)

    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

    2015-05-01

    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 (<79°N). Here we present the first central Arctic 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.

  16. Bathymetric controls on Pliocene North Atlantic and Arctic sea surface temperature and deepwater production

    USGS Publications Warehouse

    Robinson, M.M.; Valdes, P.J.; Haywood, A.M.; Dowsett, H.J.; Hill, D.J.; Jones, S.M.

    2011-01-01

    The mid-Pliocene warm period (MPWP; ~. 3.3 to 3.0. Ma) is the most recent interval in Earth's history in which global temperatures reached and remained at levels similar to those projected for the near future. The distribution of global warmth, however, was different than today in that the high latitudes warmed more than the tropics. Multiple temperature proxies indicate significant sea surface warming in the North Atlantic and Arctic Oceans during the MPWP, but predictions from a fully coupled ocean-atmosphere model (HadCM3) have so far been unable to fully predict the large scale of sea surface warming in the high latitudes. If climate proxies accurately represent Pliocene conditions, and if no weakness exists in the physics of the model, then model boundary conditions may be in error. Here we alter a single boundary condition (bathymetry) to examine if Pliocene high latitude warming was aided by an increase in poleward heat transport due to changes in the subsidence of North Atlantic Ocean ridges. We find an increase in both Arctic sea surface temperature and deepwater production in model experiments that incorporate a deepened Greenland-Scotland Ridge. These results offer both a mechanism for the warming in the North Atlantic and Arctic Oceans indicated by numerous proxies and an explanation for the apparent disparity between proxy data and model simulations of Pliocene northern North Atlantic and Arctic Ocean conditions. Determining the causes of Pliocene warmth remains critical to fully understanding comparisons of the Pliocene warm period to possible future climate change scenarios. ?? 2011.

  17. Concept Study: Exploration and Production in Environmentally Sensitive Arctic Areas

    SciTech Connect

    Shirish Patil; Rich Haut; Tom Williams; Yuri Shur; Mikhail Kanevskiy; Cathy Hanks; Michael Lilly

    2008-12-31

    The Alaska North Slope offers one of the best prospects for increasing U.S. domestic oil and gas production. However, this region faces some of the greatest environmental and logistical challenges to oil and gas production in the world. A number of studies have shown that weather patterns in this region are warming, and the number of days the tundra surface is adequately frozen for tundra travel each year has declined. Operators are not allowed to explore in undeveloped areas until the tundra is sufficiently frozen and adequate snow cover is present. Spring breakup then forces rapid evacuation of the area prior to snowmelt. Using the best available methods, exploration in remote arctic areas can take up to three years to identify a commercial discovery, and then years to build the infrastructure to develop and produce. This makes new exploration costly. It also increases the costs of maintaining field infrastructure, pipeline inspections, and environmental restoration efforts. New technologies are needed, or oil and gas resources may never be developed outside limited exploration stepouts from existing infrastructure. Industry has identified certain low-impact technologies suitable for operations, and has made improvements to reduce the footprint and impact on the environment. Additional improvements are needed for exploration and economic field development and end-of-field restoration. One operator-Anadarko Petroleum Corporation-built a prototype platform for drilling wells in the Arctic that is elevated, modular, and mobile. The system was tested while drilling one of the first hydrate exploration wells in Alaska during 2003-2004. This technology was identified as a potentially enabling technology by the ongoing Joint Industry Program (JIP) Environmentally Friendly Drilling (EFD) program. The EFD is headed by Texas A&M University and the Houston Advanced Research Center (HARC), and is co-funded by the National Energy Technology Laboratory (NETL). The EFD

  18. Physiological and ecological effects of increasing temperature on fish production in lakes of Arctic Alaska.

    PubMed

    Carey, Michael P; Zimmerman, Christian E

    2014-05-01

    Lake ecosystems in the Arctic are changing rapidly due to climate warming. Lakes are sensitive integrators of climate-induced changes and prominent features across the Arctic landscape, especially in lowland permafrost regions such as the Arctic Coastal Plain of Alaska. Despite many studies on the implications of climate warming, how fish populations will respond to lake changes is uncertain for Arctic ecosystems. Least Cisco (Coregonus sardinella) is a bellwether for Arctic lakes as an important consumer and prey resource. To explore the consequences of climate warming, we used a bioenergetics model to simulate changes in Least Cisco production under future climate scenarios for lakes on the Arctic Coastal Plain. First, we used current temperatures to fit Least Cisco consumption to observed annual growth. We then estimated growth, holding food availability, and then feeding rate constant, for future projections of temperature. Projected warmer water temperatures resulted in reduced Least Cisco production, especially for larger size classes, when food availability was held constant. While holding feeding rate constant, production of Least Cisco increased under all future scenarios with progressively more growth in warmer temperatures. Higher variability occurred with longer projections of time mirroring the expanding uncertainty in climate predictions further into the future. In addition to direct temperature effects on Least Cisco growth, we also considered changes in lake ice phenology and prey resources for Least Cisco. A shorter period of ice cover resulted in increased production, similar to warming temperatures. Altering prey quality had a larger effect on fish production in summer than winter and increased relative growth of younger rather than older age classes of Least Cisco. Overall, we predicted increased production of Least Cisco due to climate warming in lakes of Arctic Alaska. Understanding the implications of increased production of Least Cisco to

  19. Variability of Arctic Sea Ice as Determined from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    1999-01-01

    The compiled, quality-controlled satellite multichannel passive-microwave record of polar sea ice now spans over 18 years, from November 1978 through December 1996, and is revealing considerable information about the Arctic sea ice cover and its variability. The information includes data on ice concentrations (percent areal coverages of ice), ice extents, ice melt, ice velocities, the seasonal cycle of the ice, the interannual variability of the ice, the frequency of ice coverage, and the length of the sea ice season. The data reveal marked regional and interannual variabilities, as well as some statistically significant trends. For the north polar ice cover as a whole, maximum ice extents varied over a range of 14,700,000 - 15,900,000 sq km, while individual regions experienced much greater percent variations, for instance, with the Greenland Sea having a range of 740,000 - 1,110,000 sq km in its yearly maximum ice coverage. In spite of the large variations from year to year and region to region, overall the Arctic ice extents showed a statistically significant, 2.80% / decade negative trend over the 18.2-year period. Ice season lengths, which vary from only a few weeks near the ice margins to the full year in the large region of perennial ice coverage, also experienced interannual variability, along with spatially coherent overall trends. Linear least squares trends show the sea ice season to have lengthened in much of the Bering Sea, Baffin Bay, the Davis Strait, and the Labrador Sea, but to have shortened over a much larger area, including the Sea of Okhotsk, the Greenland Sea, the Barents Sea, and the southeastern Arctic.

  20. The effects of the Arctic haze as determined from airborne radiometric measurements during AGASP II

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.; Ackerman, Thomas P.; Gore, Warren J. Y.

    1989-01-01

    The effect of the Arctic-haze aerosol on the parameters of solar radiation was investigated using airborne radiometric measurements of radiation parameters during the second Arctic Gas and Aerosol Sampling Project. Simultaneously with absorption measurements, optical depths and total, direct, and scattered radiation fields were determined. The experimentally determined parameters were used to define an aerosol model, which was then used to calculate atmospheric heating rate profiles. It was found that, besides the increased absorption (30 to 40 percent) and scattering of radiation by the atmosphere, Arctic haze reduces the surface absorption of solar energy by 6 to 10 percent, and the effective planetary albedo over ice surfaces by 3 to 6 percent.

  1. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    NASA Technical Reports Server (NTRS)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  2. TOC and satellite-sensed chlorophyll and primary production at the Arctic Front in the Nordic Seas

    NASA Astrophysics Data System (ADS)

    Børsheim, Knut Yngve; Milutinović, Svetlana; Drinkwater, Kenneth F.

    2014-11-01

    In the Arctic Front region south of Jan Mayen, vertical profiles of Total Organic Carbon (TOC) and hydrographic variables were measured during 3 weeks in June 2007. From time series of satellite-sensed chlorophyll, it was determined that the field studies took place in the aftermath of the culmination of the spring bloom, both on the Arctic (Icelandic Sea) and Atlantic (Norwegian Sea) sides of the Arctic Front. TOC in the upper 50 m was on average 60.9 ± 7.6 μM C on the Arctic side and 62.3 ± 6.8 μM C on the Atlantic side. Average in situ fluorescence was higher on the Atlantic side. Annual primary production calculated from satellite imagery showed no enhancement at the Front. To place the Frontal measurements in a larger perspective, satellite imagery over the entire Nordic (Greenland-Icelandic-Norwegian) Seas between 1998 and 2012 were studied. They showed that north of Jan Mayen the spring blooms normally last longer and culminate later with a higher concentration of chlorophyll at the peak in the colder water on the west side of the Front than in the Norwegian Sea. In the year of our expedition, the maximal concentration of satellite-sensed chlorophyll at spring bloom was three times higher in the central Greenland Sea than in the Norwegian Sea. Along the Arctic Front the maximal concentration of satellite sensed chlorophyll was always lower than in the central basins both west and east of the Front. The ordinal date of maximal spring bloom concentration of chlorophyll was negatively correlated with the maximal spring bloom chlorophyll concentration in the Norwegian and Icelandic Seas, but uncorrelated in the Greenland Sea. Interannual variation of primary production and maximal chlorophyll concentration was larger in the Greenland Sea then in the Icelandic and Norwegian Seas and we hypothesize that some of this variation is influenced by difference in energy efficiency between phototrophs and heterotrophs at low temperatures.

  3. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Holding, J. M.; Duarte, C. M.; Sanz-Martín, M.; Mesa, E.; Arrieta, J. M.; Chierici, M.; Hendriks, I. E.; García-Corral, L. S.; Regaudie-de-Gioux, A.; Delgado, A.; Reigstad, M.; Wassmann, P.; Agustí, S.

    2015-12-01

    The Arctic Ocean is warming at two to three times the global rate and is perceived to be a bellwether for ocean acidification. Increased CO2 concentrations are expected to have a fertilization effect on marine autotrophs, and higher temperatures should lead to increased rates of planktonic primary production. Yet, simultaneous assessment of warming and increased CO2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO2-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range of 145-2,099 μatm however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO2-enhanced primary production has significant implications for metabolic balance in a warmer, CO2-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.

  4. Arctic foxes as ecosystem engineers: increased soil nutrients lead to increased plant productivity on fox dens

    PubMed Central

    Gharajehdaghipour, Tazarve; Roth, James D.; Fafard, Paul M.; Markham, John H.

    2016-01-01

    Top predators can provide fundamental ecosystem services such as nutrient cycling, and their impact can be even greater in environments with low nutrients and productivity, such as Arctic tundra. We estimated the effects of Arctic fox (Vulpes lagopus) denning on soil nutrient dynamics and vegetation production near Churchill, Manitoba in June and August 2014. Soils from fox dens contained higher nutrient levels in June (71% more inorganic nitrogen, 1195% more extractable phosphorous) and in August (242% more inorganic nitrogen, 191% more extractable phosphorous) than adjacent control sites. Inorganic nitrogen levels decreased from June to August on both dens and controls, whereas extractable phosphorous increased. Pup production the previous year, which should enhance nutrient deposition (from urine, feces, and decomposing prey), did not affect soil nutrient concentrations, suggesting the impact of Arctic foxes persists >1 year. Dens supported 2.8 times greater vegetation biomass in August, but δ15N values in sea lyme grass (Leymus mollis) were unaffected by denning. By concentrating nutrients on dens Arctic foxes enhance nutrient cycling as an ecosystem service and thus engineer Arctic ecosystems on local scales. The enhanced productivity in patches on the landscape could subsequently affect plant diversity and the dispersion of herbivores on the tundra. PMID:27045973

  5. Arctic foxes as ecosystem engineers: increased soil nutrients lead to increased plant productivity on fox dens.

    PubMed

    Gharajehdaghipour, Tazarve; Roth, James D; Fafard, Paul M; Markham, John H

    2016-01-01

    Top predators can provide fundamental ecosystem services such as nutrient cycling, and their impact can be even greater in environments with low nutrients and productivity, such as Arctic tundra. We estimated the effects of Arctic fox (Vulpes lagopus) denning on soil nutrient dynamics and vegetation production near Churchill, Manitoba in June and August 2014. Soils from fox dens contained higher nutrient levels in June (71% more inorganic nitrogen, 1195% more extractable phosphorous) and in August (242% more inorganic nitrogen, 191% more extractable phosphorous) than adjacent control sites. Inorganic nitrogen levels decreased from June to August on both dens and controls, whereas extractable phosphorous increased. Pup production the previous year, which should enhance nutrient deposition (from urine, feces, and decomposing prey), did not affect soil nutrient concentrations, suggesting the impact of Arctic foxes persists >1 year. Dens supported 2.8 times greater vegetation biomass in August, but δ(15)N values in sea lyme grass (Leymus mollis) were unaffected by denning. By concentrating nutrients on dens Arctic foxes enhance nutrient cycling as an ecosystem service and thus engineer Arctic ecosystems on local scales. The enhanced productivity in patches on the landscape could subsequently affect plant diversity and the dispersion of herbivores on the tundra. PMID:27045973

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

    NASA Astrophysics Data System (ADS)

    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 < 0.001, N = 38), suggesting that BP was subject to bottom-up control by carbon supply. Integrated BP data showed three distinct periods: fall-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.

  7. Ecosystem model intercomparison of under-ice and total primary production in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Jin, Meibing; Popova, Ekaterina E.; Zhang, Jinlun; Ji, Rubao; Pendleton, Daniel; Varpe, Øystein; Yool, Andrew; Lee, Younjoo J.

    2016-01-01

    Previous observational studies have found increasing primary production (PP) in response to declining sea ice cover in the Arctic Ocean. In this study, under-ice PP was assessed based on three coupled ice-ocean-ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project. All models showed good agreement with under-ice measurements of surface chlorophyll-a concentration and vertically integrated PP rates during the main under-ice production period, from mid-May to September. Further, modeled 30-year (1980-2009) mean values and spatial patterns of sea ice concentration compared well with remote sensing data. Under-ice PP was higher in the Arctic shelf seas than in the Arctic Basin, but ratios of under-ice PP over total PP were spatially correlated with annual mean sea ice concentration, with higher ratios in higher ice concentration regions. Decreases in sea ice from 1980 to 2009 were correlated significantly with increases in total PP and decreases in the under-ice PP/total PP ratio for most of the Arctic, but nonsignificantly related to under-ice PP, especially in marginal ice zones. Total PP within the Arctic Circle increased at an annual rate of between 3.2 and 8.0 Tg C/yr from 1980 to 2009. This increase in total PP was due mainly to a PP increase in open water, including increases in both open water area and PP rate per unit area, and therefore much stronger than the changes in under-ice PP. All models suggested that, on a pan-Arctic scale, the fraction of under-ice PP declined with declining sea ice cover over the last three decades.

  8. Future change in ocean productivity: Is the Arctic the new Atlantic?

    NASA Astrophysics Data System (ADS)

    Yool, A.; Popova, E. E.; Coward, A. C.

    2015-12-01

    One of the most characteristic features in ocean productivity is the North Atlantic spring bloom. Responding to seasonal increases in irradiance and stratification, surface phytopopulations rise significantly, a pattern that visibly tracks poleward into summer. While blooms also occur in the Arctic Ocean, they are constrained by the sea-ice and strong vertical stratification that characterize this region. However, Arctic sea-ice is currently declining, and forecasts suggest this may lead to completely ice-free summers by the mid-21st century. Such change may open the Arctic up to Atlantic-style spring blooms, and do so at the same time as Atlantic productivity is threatened by climate change-driven ocean stratification. Here we use low and high-resolution instances of a coupled ocean-biogeochemistry model, NEMO-MEDUSA, to investigate productivity. Drivers of present-day patterns are identified, and changes in these across a climate change scenario (IPCC RCP 8.5) are analyzed. We find a globally significant decline in North Atlantic productivity (> -20%) by 2100, and a correspondingly significant rise in the Arctic (> +50%). However, rather than the future Arctic coming to resemble the current Atlantic, both regions are instead transitioning to a common, low nutrient regime. The North Pacific provides a counterexample where nutrients remain high and productivity increases with elevated temperature. These responses to climate change in the Atlantic and Arctic are common between model resolutions, suggesting an independence from resolution for key impacts. However, some responses, such as those in the North Pacific, differ between the simulations, suggesting the reverse and supporting the drive to more fine-scale resolutions. This article was corrected on 5 JAN 2016. See the end of the full text for details.

  9. Arctic Climate Systems Analysis

    SciTech Connect

    Ivey, Mark D.; Robinson, David G.; Boslough, Mark B.; Backus, George A.; Peterson, Kara J.; van Bloemen Waanders, Bart G.; Swiler, Laura Painton; Desilets, Darin Maurice; Reinert, Rhonda Karen

    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.

  10. Determination of Offgassed Products

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A technician at Marshall Space Flight Center's Materials Combustion Research Facility begins the Determination of Offgassed Products Test to determine the identity and quantity of volatile offgassed products from materials and assembled articles. Materials are measured, weighed, and loaded into a clean toxicity chamber (pictured). The chamber is purged with high-purity air and loaded into an oven where it will be held at 120 degrees Fahrenheit (48.9 degrees Celsius) for 72 hours. At the end of the 72-hour period, the chamber is removed and allowed to cool to room temperature. Gas samples are taken from the chamber and analyzed using gas chromatography and mass spectrometry. From this, the quantity of the material that may be used safely in habitable areas of spacecraft is determined. This test also determines whether a flight hardware item may be flown safely in a crew compartment. Everything going into space with the astronauts is tested prior to flight to ensure the health and safety of the crew members.

  11. Benthic macrofaunal production for a typical shelf-slope-basin region in the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Lin, Heshan; Wang, Jianjun; Liu, Kun; He, Xuebao; Lin, Junhui; Huang, Yaqin; Zhang, Shuyi; Mou, Jianfeng; Zheng, Chengxing; Wang, Yu

    2016-02-01

    Secondary production by macrofaunal communities in the western Arctic Ocean were quantified during the 4th and 5th Chinese Arctic Scientific Expeditions. The total production and P/B ratio for each sector ranged from 3.8 (±7.9) to 615.6 (±635.5) kJ m-2 yr-1 and 0.5 (± 0.2) to 0.7 (± 0.2) yr-1, respectively. The shallow shelves in the western Arctic Ocean exhibited particularly high production (178.7-615.6 kJ m-2 yr-1), particularly in the two "hotspots" - the southern and northeastern (around Barrow Canyon) Chukchi Sea. Benthic macrofaunal production decreased sharply with depth and latitude along a shelf-slope-basin transect, with values of 17.0-269.8 kJ m-2 yr-1 in slope regions and 3.8-10.1 kJ m-2 yr-1 in basins. Redundancy analysis indicated that hydrological characteristics (depth, bottom temperature and salinity) and granulometric parameters (mean particle size, % sand and % clay) show significant positive/negative correlations with total production. These correlations revealed that the dominant factors influencing benthic production are the habitat type and food supply from the overlying water column. In the Arctic, the extreme environmental conditions and low temperature constrain macrofaunal metabolic processes, such that food and energy are primarily used to increase body mass rather than for reproduction. Hence, energy turnover is relatively low at high latitudes. These data further our understanding of benthic production processes and ecosystem dynamics in the context of rapid climate change in the western Arctic Ocean.

  12. Melt ponds on Arctic sea ice determined from MODIS satellite data using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Rösel, A.; Kaleschke, L.; Birnbaum, G.

    2011-10-01

    Melt ponds on sea ice strongly reduce the surface albedo and accelerate the decay of Arctic sea ice. Due to different spectral properties of snow, ice, and water, the fractional coverage of these distinct surface types can be derived from multispectral sensors like MODIS using a spectral unmixing algorithm. The unmixing was implemented using a multilayer perceptron (MLP) to reduce computational costs. Arctic-wide melt pond fractions and sea ice concentrations are derived from the level 3 MODIS surface reflectance product. The validation of the MODIS melt pond data set was conducted with aerial photos from the MELTEX campaign 2008 in the Beaufort Sea, data sets from the National Snow and Ice Data Center (NSIDC) for 2000 and 2001 from four sites spread over the entire Arctic, and with ship observations from the trans-Arctic HOTRAX cruise in 2005. The root-mean-square errors (RMSE) range from 3.8 % for the comparison with HOTRAX data, over 10.7 % for the comparison with NSIDC data, to 10.3 % and 11.4 % for the comparison with MELTEX data, with correlations coefficients ranging from R2 = 0.28 to R2 = 0.45. The mean annual cycle of the melt pond fraction for the entire Arctic shows a strong increase in June, reaching a maximum of 15 % by the end of June. The zonal mean of melt pond fractions indicates a dependence of the temporal development of melt ponds from the geographical latitude, and has its maximum in mid-July in latitudes between 80° and 88° N. Furthermore, the MODIS results are used to estimate the influence of melt ponds on retrievals of sea ice concentrations from passive microwave data. Results from a case study comparing sea ice concentrations from ASI-, NASA Team 2-, and Bootstrap-algorithms with MODIS sea ice concentrations indicate an underestimation of around 40 % for sea ice concentrations retrieved with microwave algorithms.

  13. Primary production and biochemical compositions in Arctic melt ponds.

    NASA Astrophysics Data System (ADS)

    Lee, S.

    2015-12-01

    Areal extent of melt ponds within sea ice recently have increased during the arctic summer but the biological impacts of these changes on the arctic marine ecosystem have rarely been studied. Our survey of environmental conditions in melt ponds was conducted in 22 at sea ice camp 1 and 11 ponds at camp 2, respectively during the Korean Arctic expedition in 2014. The temperature range of melt ponds showed low variability at sea ice camp 1 (-1.3~0.8 °C) and camp 2 (-1.5~0.4 °C). In contrast, the salinity represented high variations ranging from 0.1 to 26.8 (mean ± S.D. = 16.7 ± 10.8) and 0 to 26.9 (mean ± S.D. = 12.3 ± 11.6), respectively. The average chlorophyll a (chl-a) concentrations were 0.124 mg m-2 (S.D. = ± 0.121 mg m-2) and 0.158 mg m-2 (S.D. = ± 0.067 mg m-2) in melt ponds, respectively at camp 1 and camp 2. Middle sized cells of phytoplankton (2-20 μm) were predominant in melt ponds accounting for 78 % and 63 % of total chl-a concentration at camp 1 and 2, respectively. The carbon uptake rates of phytoplankton in melt ponds ranged from 0.001 to 0.080 mg C m-3 h-1 (mean ± S.D. = 0.025 ± 0.024 mg C m-3 h-1) at camp 1 and 0.022 to 0.21 mg C m-3 h-1 (mean ± S.D. = 0.077 ± 0.006 mg C m-3 h-1) at camp 2 which is about three times higher than those of camp 1. The biochemical compositions averaged from various melt ponds were 35% (S.D. = ± 14.9%), 40% (S.D. = ± 13.2%), and 25% (S.D. = ± 12.9%), respectively for lipids, carbohydrates, and proteins at camp 1. In comparison, the overall average compositions of lipids, carbohydrates, and proteins were 29% (S.D. = ± 11.4%), 51% (S.D. = ± 9.8%), and 20% (S.D. = ± 7.9%), respectively at camp 2.

  14. Nitrous oxide production and emission in high arctic soils of NW Greenland

    NASA Astrophysics Data System (ADS)

    Stills, A.; Lupascu, M.; Czimczik, C. I.; Sharp, E. D.; Welker, J. M.; Schaeffer, S. M.

    2010-12-01

    Nitrous oxide (N2O) is a potent ozone depleting greenhouse gas with a global warming potential 298 times larger than carbon dioxide (CO2 on a 100-year time scale. Recent studies identified arctic soils undergoing thawing and changes in drainage as potentially large sources of N2O to the atmosphere. More in situ2O production in and emission from arctic soils are needed to understand ecosystem feedbacks to climate change in high arctic tundra, and the role of high latitudes in the global N2O budget. We monitored the concentration of N2O in soils and emissions of N2O to the atmosphere from prostrate shrub tundra in NW Greenland under current and future climate conditions. Measurements were made monthly from June to August 2010 at a long-term climate change experiment started in 2003 consisting of +2oC warming (T1), +4oC warming (T2), +50% summer precipitation (W), +4oC × +50% summer precipitation (T2W), and control (C). In each treatment, N2O was monitored from vegetated and barren soils. In addition, we quantified nitrogen (N) mineralization rates. The concentration of N2O in soils was measured by sampling air from permanent wells ranging from 20 to 90 cm soil depth. N2O emissions were measured every 15 minutes for one hour using opaque, static chambers. Nitrous oxide samples were collected manually with syringes and stored in pre-evacuated glass vials with butyl rubber septa and aluminum crimp. The vials were sealed with silicon, shipped to UC Irvine, and analyzed by GC-ECD (Shimadzu GC-2014). To determine soil N mineralization rates, resin bags were installed under PVC cores from 8 to 10 cm in early spring in all treatments. Bags were removed at peak season. A second set was installed to capture end-of-season mineralization rates. Resin bags were extracted for future analysis of total accumulated ammonium and nitrate. Soil cores concurrently collected with resin bag installation and removal will be analyzed for % C and N, and were extracted for future analysis

  15. Relationships linking primary production, sea ice melting, and biogenic aerosol in the Arctic

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Lazzara, L.; Marchese, C.; Dayan, U.; Ascanius, S. E.; Cacciani, M.; Caiazzo, L.; Di Biagio, C.; Di Iorio, T.; di Sarra, A.; Eriksen, P.; Fani, F.; Giardi, F.; Meloni, D.; Muscari, G.; Pace, G.; Severi, M.; Traversi, R.; Udisti, R.

    2016-07-01

    This study examines the relationships linking methanesulfonic acid (MSA, arising from the atmospheric oxidation of the biogenic dimethylsulfide, DMS) in atmospheric aerosol, satellite-derived chlorophyll a (Chl-a), and oceanic primary production (PP), also as a function of sea ice melting (SIM) and extension of the ice free area in the marginal ice zone (IF-MIZ) in the Arctic. MSA was determined in PM10 samples collected over the period 2010-2012 at two Arctic sites, Ny Ålesund (78.9°N, 11.9°E), Svalbard islands, and Thule Air Base (76.5°N, 68.8°W), Greenland. PP is calculated by means of a bio-optical, physiologically based, semi-analytical model in the potential source areas located in the surrounding oceanic regions (Barents and Greenland Seas for Ny Ålesund, and Baffin Bay for Thule). Chl-a peaks in May in the Barents sea and in the Baffin Bay, and has maxima in June in the Greenland sea; PP follows the same seasonal pattern of Chl-a, although the differences in absolute values of PP in the three seas during the blooms are less marked than for Chl-a. MSA shows a better correlation with PP than with Chl-a, besides, the source intensity (expressed by PP) is able to explain more than 30% of the MSA variability at the two sites; the other factors explaining the MSA variability are taxonomic differences in the phytoplanktonic assemblages, and transport processes from the DMS source areas to the sampling sites. The taxonomic differences are also evident from the slopes of the correlation plots between MSA and PP: similar slopes (in the range 34.2-36.2 ng m-3of MSA/(gC m-2 d-1)) are found for the correlation between MSA at Ny Ålesund and PP in Barents Sea, and between MSA at Thule and PP in the Baffin Bay; conversely, the slope of the correlation between MSA at Ny Ålesund and PP in the Greenland Sea in summer is smaller (16.7 ng m-3of MSA/(gC m-2 d-1)). This is due to the fact that DMS emission from the Barents Sea and Baffin Bay is mainly related to the MIZ

  16. Modeling seasonality of ice and ocean carbon production in the Arctic

    NASA Astrophysics Data System (ADS)

    Jin, M.; Deal, C. M.; Ji, R.

    2011-12-01

    In the Arctic Ocean, both phytoplankton and sea ice algae are important contributors to the primary production and the arctic food web. Copepod in the arctic regions have developed their feeding habit depending on the timing between the ice algal bloom and the subsequent phytoplankton bloom. A mismatch of the timing due to climate changes could have dramatic consequences on the food web as shown by some regional observations. In this study, a global coupled ice-ocean-ecosystem model was used to assess the seasonality of the ice algal and phytoplankton blooms in the arctic. The ice-ocean ecosystem modules are fully coupled in the physical model POP-CICE (Parallel Ocean Program- Los Alamos Sea Ice Model). The model results are compared with various observations. The modeled ice and ocean carbon production were analyzed by regions and their linkage to the physical environment changes (such as changes of ice concentration and water temperature, and light intensity etc.) between low- and high-ice years.

  17. Photosynthetic production in the central Arctic Ocean during the record sea-ice minimum in 2012

    NASA Astrophysics Data System (ADS)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-06-01

    The ice-covered central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primary production and of the nutrient supply with increasing warming. This study presents results from the central Arctic Ocean collected during summer 2012, when sea-ice extent reached its lowest ever recorded since the onset of satellite observations. Net primary productivity (NPP) was measured in the water column, sea ice and melt ponds by 14CO2 uptake at different irradiances. Photosynthesis vs. irradiance (PI) curves were established in laboratory experiments and used to upscale measured NPP to the deep Eurasian Basin (north of 78° N) using the irradiance-based Central Arctic Ocean Primary Productivity (CAOPP) model. In addition, new annual production has been calculated from the seasonal nutrient drawdown in the mixed layer since last winter. Results show that ice algae can contribute up to 60% to primary production in the central Arctic Ocean at the end of the productive season (August-September). The ice-covered water column has lower NPP rates than open water due to light limitation in late summer. As indicated by the nutrient ratios in the euphotic zone, nitrate was limiting primary production in the deep Eurasian Basin close to the Laptev Sea area, while silicate was the main limiting nutrient at the ice margin near the Atlantic inflow. Although sea-ice cover was substantially reduced in 2012, total annual new production in the Eurasian Basin was 17 ± 7 Tg C yr-1, which is within the range of estimates of previous years. However, when adding the contribution by sub-ice algae, the annual production for the deep Eurasian Basin (north of 78° N) could double previous estimates for that area with a surplus of 16 Tg C yr-1. Our data suggest that sub-ice algae are an

  18. Photosynthetic production in the Central Arctic during the record sea-ice minimum in 2012

    NASA Astrophysics Data System (ADS)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-02-01

    The ice-covered Central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primary production and of the nutrient supply with increasing warming. This study presents results from the Central Arctic Ocean collected during summer 2012, when sea-ice reached a minimum extent since the onset of satellite observations. Net primary productivity (NPP) was measured in the water column, sea ice and melt ponds by 14CO2 uptake at different irradiances. Photosynthesis vs. irradiance (PI) curves were established in laboratory experiments and used to upscale measured NPP to the deep Eurasian Basin (north of 78° N) using the irradiance-based Central Arctic Ocean Primary Productivity (CAOPP) model. In addition, new annual production was calculated from the seasonal nutrient drawdown in the mixed layer since last winter. Results show that ice algae can contribute up to 60% to primary production in the Central Arctic at the end of the season. The ice-covered water column has lower NPP rates than open water due to light limitation. As indicated by the nutrient ratios in the euphotic zone, nitrate was limiting primary production in the deep Eurasian Basin close to the Laptev Sea area, while silicate was the main limiting nutrient at the ice margin near the Atlantic inflow. Although sea-ice cover was substantially reduced in 2012, total annual new production in the Eurasian Basin was 17 ± 7 Tg C yr-1, which is within the range of estimates of previous years. However, when adding the contribution by sub-ice algae, the annual production for the deep Eurasian Basin (north of 78° N) could double previous estimates for that area with a surplus of 16 Tg C yr-1. Our data suggest that sub-ice algae are an important component of the ice-covered Central Arctic productivity. It

  19. Predictive modeling of plant productivity in the Russian Arctic using satellite data

    NASA Astrophysics Data System (ADS)

    Anisimov, O. A.; Zhiltcova, Ye. L.; Razzhivin, V. Yu.

    2015-12-01

    The NOAA satellite data for 1982-2012 are used to analyze current changes in plant productivity of the Russian boreal and tundra zones. Trends in the Normalized Difference Vegetation Index (NDVI) are calculated separately for the vegetation zones in the European, West Siberian, East Siberian, and Far East sectors of the Russian Arctic and are compared with each other. This index is the normalized difference in reflectance between the red and infrared regions of the spectrum and is widely used as an indicator of the photosynthetically active biomass amount. Multifactorial statistical analysis is used to analyze the link between the plant productivity characterized by NDVI and predictive climatic indices characterizing the temperature regime and precipitation. A statistical model is developed on the basis of the resulting set of regression equations and is used with a climatic projection to predict plant productivity changes across the zonal gradient from northern tundra to boreal forests. According to our results, the current increase in plant productivity, which is observed in all vegetation zones in the Arctic, will continue in the coming decades. By the mid-21st century, productivity may increase by as much as 30% of its current value in selected zones of arctic vegetation.

  20. SAR Altimetry for Mean Sea Surface Determination in the Arctic DTU15MSS

    NASA Astrophysics Data System (ADS)

    Piccioni, G.; Andersen, O. B.; Stenseng, L.

    2015-12-01

    A reliable MSS that includes high-latitude regions within the 82 degree parallel is required for the Sentinel-3 data processing. In this paper we present the new DTU15MSS which is an update of the DTU13MSS with more years of CryoSat-2. CryoSat-2 offers a unique dataset in the Arctic Ocean for testing SAR altimetry with nearly five years of high-resolution SAR altimetry. In the Arctic Ocean older conventional altimetry satellites (ERS-1/ERS-2/Envisat) have only been able to provide sparse data for the past 20 years. Here we present the development of the DTU13MSS in the Arctic being the latest release of the global high resolution mean sea surface from DTU Space based on 4 years/repeat of Cryostat-2. The analysis shows that Laser Altimetry from the ICESat satellite being the basis of DTU10 and DTU13MSS between 82 and 86N is now obsolete for mean sea surface determination. The study also highlight the problems of integrating altimetry from various modes (LRM, SAR and SAR-in) as well as the problems relating to the fact that the averaging period of CryoSat-2 is adjacent to the 20 years (1993-2012) period used to develop DTU13MSS. Evaluation of the new MSS is performed and comparison with existing MSS models is performed to evaluate the impact of these updates into MSS computation.

  1. The relation between productivity and species diversity in temperate-Arctic marine ecosystems.

    PubMed

    Witman, Jon D; Cusson, Mathieu; Archambault, Philippe; Pershing, Andrew J; Mieszkowska, Nova

    2008-11-01

    Energy variables, such as evapotranspiration, temperature, and productivity explain significant variation in the diversity of many groups of terrestrial plants and animals at local to global scales. Although the ocean represents the largest continuous habitat on earth with a vast spectrum of primary productivity and species richness, little is known about how productivity influences species diversity in marine systems. To search for general relationships between productivity and species richness in the ocean, we analyzed data from three different benthic marine ecosystems (epifaunal communities on subtidal rock walls, on navigation buoys in the Gulf of St. Lawrence, and Canadian Arctic macrobenthos) across local to continental spatial scales (<20 to >1000 km) using a standardized proxy for productivity, satellite-derived chlorophyll a. Theoretically, the form of the function between productivity and species richness is either monotonically increasing or decreasing, or curvilinear (hump- or U-shaped). We found three negative linear and three hump-shaped relationships between chlorophyll a and species richness out of 10 independent comparisons. Scale dependence was suggested by more prevalent diversity-productivity relationships at smaller (local, landscape) than larger (regional, continental) spatial scales. Differences in the form of the functions were more closely allied with community type than with scale, as negative linear functions were restricted to sessile epifauna while hump-shaped functions occurred in Arctic macrobenthos (mixed epifauna, infauna). In two of the data sets, (St. Lawrence epifauna and Arctic macrobenthos) significant effects of chlorophyll a co-varied with the effects of salinity, suggesting that environmental stress as well as productivity influences diversity in these marine systems. The co-varying effect of salinity may commonly arise in broad-scale studies of productivity and diversity in marine ecosystems when attempting to sample the

  2. Interactions between herbivory and warming in aboveground biomass production of arctic vegetation

    PubMed Central

    Pedersen, Christian; Post, Eric

    2008-01-01

    Background Many studies investigating the ecosystem effects of global climate change have focused on arctic ecosystems because the Arctic is expected to undergo the earliest and most pronounced changes in response to increasing global temperatures, and arctic ecosystems are considerably limited by low temperatures and permafrost. In these nutrient limited systems, a warmer climate is expected to increase plant biomass production, primarily through increases in shrubs over graminoids and forbs. But, the influence of vertebrate and invertebrate herbivores has been largely absent in studies investigating the effects of vegetation responses to climate change, despite the fact that herbivory can have a major influence on plant community composition, biomass and nutrient cycling. Here, we present results from a multi-annual field experiment investigating the effects of vertebrate herbivory on plant biomass response to simulated climate warming in arctic Greenland. Results The results after four years of treatments did not give any clear evidence of increased biomass of shrubs in response climate warming. Nor did our study indicate that vertebrate grazing mediated any increased domination of shrubs over other functional plant groups in response to warming. However, our results indicate an important role of insect outbreaks on aboveground biomass. Intense caterpillar foraging from a two-year outbreak of the moth Eurois occulta during two growing seasons may have concealed any treatment effects. However, there was some evidence suggesting that vertebrate herbivores constrain the biomass production of shrubs over graminoids and forbs. Conclusion Although inconclusive, our results were likely constrained by the overwhelming influence of an unexpected caterpillar outbreak on aboveground biomass. It is likely that the role of large vertebrate herbivores in vegetation response to warming will become more evident as this experiment proceeds and the plant community recovers from

  3. PCBs in the Arctic atmosphere: determining important driving forces using a global atmospheric transport model

    NASA Astrophysics Data System (ADS)

    Friedman, C. L.; Selin, N. E.

    2015-11-01

    We present a spatially and temporally resolved global atmospheric PCB model, driven by meteorological data, that is skilled at simulating mean atmospheric PCB concentrations and seasonal cycles in the Northern Hemisphere mid-latitudes, and mean Arctic concentrations. However, the model does not capture the observed Arctic summer maximum in atmospheric PCBs. We use the model to estimate global budgets for the International Council for the Exploration of the Sea 7 PCBs, and demonstrate that congeners that deposit more readily show lower potential for long-range transport, consistent with a recently-described "differential removal hypothesis" regarding the hemispheric transport of PCBs. Using sensitivity simulations to assess processes within, outside, or transport to the Arctic, we examine the influence of climate- and emissions-driven processes on Arctic concentrations and their effect on improving the simulated Arctic seasonal cycle. We find evidence that processes occurring outside the Arctic have a greater influence on Arctic atmospheric PCB levels than processes that occur within the Arctic. Our simulations suggest that re-emissions from sea ice melting or from the Arctic Ocean during summer would have to be unrealistically high in order to capture observed temporal trends of PCBs in the Arctic atmosphere. We conclude that mid-latitude processes are likely to have a greater effect on the Arctic under global change scenarios than re-emissions within the Arctic.

  4. PCBs in the Arctic atmosphere: determining important driving forces using a global atmospheric transport model

    NASA Astrophysics Data System (ADS)

    Friedman, Carey L.; Selin, Noelle E.

    2016-03-01

    We present a spatially and temporally resolved global atmospheric polychlorinated biphenyl (PCB) model, driven by meteorological data, that is skilled at simulating mean atmospheric PCB concentrations and seasonal cycles in the Northern Hemisphere midlatitudes and mean Arctic concentrations. However, the model does not capture the observed Arctic summer maximum in atmospheric PCBs. We use the model to estimate global budgets for seven PCB congeners, and we demonstrate that congeners that deposit more readily show lower potential for long-range transport, consistent with a recently described "differential removal hypothesis" regarding the hemispheric transport of PCBs. Using sensitivity simulations to assess processes within, outside, or transport to the Arctic, we examine the influence of climate- and emissions-driven processes on Arctic concentrations and their effect on improving the simulated Arctic seasonal cycle. We find evidence that processes occurring outside the Arctic have a greater influence on Arctic atmospheric PCB levels than processes that occur within the Arctic. Our simulations suggest that re-emissions from sea ice melting or from the Arctic Ocean during summer would have to be unrealistically high in order to capture observed temporal trends of PCBs in the Arctic atmosphere. We conclude that midlatitude processes are likely to have a greater effect on the Arctic under global change scenarios than re-emissions within the Arctic.

  5. Seasonal Changes in the Marine Production Cycles in Response to Changes in Arctic Sea Ice and Upper Ocean Circulation

    NASA Astrophysics Data System (ADS)

    Spitz, Y. H.; Ashjian, C. J.; Campbell, R. G.; Steele, M.; Zhang, J.

    2011-12-01

    Significant seasonal changes in arctic sea ice have been observed in recent years, characterized by unprecedented summer melt-back. As summer sea ice extent shrinks to record low levels, the peripheral seas of the Arctic Ocean are exposed much earlier to atmospheric surface heat flux, resulting in longer and warmer summers with more oceanic heat absorption. The changing seasonality in the arctic ice/ocean system will alter the timing, magnitude, duration, and pattern of marine production cycles by disrupting key trophic linkages and feedbacks in planktonic food webs. We are using a coupled pan-arctic Biology/Ice/Ocean Modeling and Assimilation System (BIOMAS) to investigate the changes in the patterns of seasonality in the arctic physical and biological system. Focus on specific regions of the Arctic, such as the Chukchi Sea, the Beaufort Sea and the adjacent central Arctic, reveals that changes in the timing of the spring bloom, its duration and the response of the secondary producers vary regionally. The major changes are, however, characterized by an earlier phytoplankton bloom and a slight increase of the biomass. In addition, the largest response in the secondary producers is seen in the magnitude of the microzooplankton concentration as well as in the period (early summer to late fall) over which the microzooplankton is present.

  6. Determination of Arctic sea ice variability modes on interannual timescales via nonhierarchical clustering

    NASA Astrophysics Data System (ADS)

    Fučkar, Neven-Stjepan; Guemas, Virginie; Massonnet, François; Doblas-Reyes, Francisco

    2015-04-01

    Over the modern observational era, the northern hemisphere sea ice concentration, age and thickness have experienced a sharp long-term decline superimposed with strong internal variability. Hence, there is a crucial need to identify robust patterns of Arctic sea ice variability on interannual timescales and disentangle them from the long-term trend in noisy datasets. The principal component analysis (PCA) is a versatile and broadly used method for the study of climate variability. However, the PCA has several limiting aspects because it assumes that all modes of variability have symmetry between positive and negative phases, and suppresses nonlinearities by using a linear covariance matrix. Clustering methods offer an alternative set of dimension reduction tools that are more robust and capable of taking into account possible nonlinear characteristics of a climate field. Cluster analysis aggregates data into groups or clusters based on their distance, to simultaneously minimize the distance between data points in a given cluster and maximize the distance between the centers of the clusters. We extract modes of Arctic interannual sea-ice variability with nonhierarchical K-means cluster analysis and investigate the mechanisms leading to these modes. Our focus is on the sea ice thickness (SIT) as the base variable for clustering because SIT holds most of the climate memory for variability and predictability on interannual timescales. We primarily use global reconstructions of sea ice fields with a state-of-the-art ocean-sea-ice model, but we also verify the robustness of determined clusters in other Arctic sea ice datasets. Applied cluster analysis over the 1958-2013 period shows that the optimal number of detrended SIT clusters is K=3. Determined SIT cluster patterns and their time series of occurrence are rather similar between different seasons and months. Two opposite thermodynamic modes are characterized with prevailing negative or positive SIT anomalies over the

  7. Traditional Potato Production Beyond the Arctic Circle in Alaska, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The role of traditional agricultural production is receiving renewed attention, especially in circumpolar environments facing challenges and opportunities associated to climate change. Issues such as food security, biodiversity, natural resources preservation, and traditional farming are receiving t...

  8. Arctic technology and policy

    SciTech Connect

    Dyer, I.; Chryssostomidis, C.

    1984-01-01

    Topics covered include: legal regime of the arctic, including national and international legal frameworks that govern arctic resource development; environmental policy and socio-economic issues, focusing on the political and economic considerations of LNG transport in icebound waterways; risk and safety assessment for arctic offshore projects, drilling systems for the arctic; arctic offshore technology, including island, steel, and concrete structures; icebreaking technology, focusing on the current state of the art and indicating future research areas; arctic oceanography, summarizing characteristics of ice from field experiments pertaining to the design of structures, ships, and pipelines; arctic seismic exploration, detailing signal processes for underwater communication in the context of arctic geology and geophysics; ice morphology, providing information about ice shapes, particularly critical to the determination of overall strength of ice masses; remote sensing; modeling of arctic ice fields, including information about the design and construction of offshore facilities in polar areas; and engineering properties of ice, providing theoretical and experimental studies.

  9. The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.

    PubMed

    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. PMID:19323694

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

    NASA Technical Reports Server (NTRS)

    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.; daSilva, A.; Diskin, G. S.; Duncan, B. N.; Huey, L. C.; Knapp, D. J.; Montzka, D. D.; Nielsen, J. E.; Olson, J. R.; Pawson, S.; Weinheimer, A. J.

    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

  11. Temperature effects on net greenhouse gas production and bacterial communities in arctic thaw ponds.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Lovejoy, Connie

    2016-08-01

    One consequence of High Arctic permafrost thawing is the formation of small ponds, which release greenhouse gases (GHG) from stored carbon through microbial activity. Under a climate with higher summer air temperatures and longer ice-free seasons, sediments of shallow ponds are likely to become warmer, which could influence enzyme kinetics or select for less cryophilic microbes. There is little data on the direct temperature effects on GHG production and consumption or on microbial communities' composition in Arctic ponds. We investigated GHG production over 16 days at 4°C and 9°C in sediments collected from four thaw ponds. Consistent with an enzymatic response, production rates of CO2 and CH4 were significantly greater at higher temperatures, with Q10 varying from 1.2 to 2.5. The bacterial community composition from one pond was followed through the incubation by targeting the V6-V8 variable regions of the 16S rRNA gene and 16S rRNA. Several rare taxa detected from rRNA accounted for significant community compositional changes. At the higher temperature, the relative community contribution from Bacteroidetes decreased by 15% with compensating increases in Betaproteobacteria, Alphaproteobacteria, Firmicutes, Acidobacteria, Verrucomicrobia and Actinobacteria. The increase in experimental GHG production accompanied by changes in community indicates an additional factor to consider in sediment environments when evaluating future climate scenarios. PMID:27288196

  12. Metabolic and trophic interactions modulate methane production by Arctic peat microbiota in response to warming.

    PubMed

    Tveit, Alexander Tøsdal; Urich, Tim; Frenzel, Peter; Svenning, Mette Marianne

    2015-05-12

    Arctic permafrost soils store large amounts of soil organic carbon (SOC) that could be released into the atmosphere as methane (CH4) in a future warmer climate. How warming affects the complex microbial network decomposing SOC is not understood. We studied CH4 production of Arctic peat soil microbiota in anoxic microcosms over a temperature gradient from 1 to 30 °C, combining metatranscriptomic, metagenomic, and targeted metabolic profiling. The CH4 production rate at 4 °C was 25% of that at 25 °C and increased rapidly with temperature, driven by fast adaptations of microbial community structure, metabolic network of SOC decomposition, and trophic interactions. Below 7 °C, syntrophic propionate oxidation was the rate-limiting step for CH4 production; above this threshold temperature, polysaccharide hydrolysis became rate limiting. This change was associated with a shift within the functional guild for syntrophic propionate oxidation, with Firmicutes being replaced by Bacteroidetes. Correspondingly, there was a shift from the formate- and H2-using Methanobacteriales to Methanomicrobiales and from the acetotrophic Methanosarcinaceae to Methanosaetaceae. Methanogenesis from methylamines, probably stemming from degradation of bacterial cells, became more important with increasing temperature and corresponded with an increased relative abundance of predatory protists of the phylum Cercozoa. We concluded that Arctic peat microbiota responds rapidly to increased temperatures by modulating metabolic and trophic interactions so that CH4 is always highly produced: The microbial community adapts through taxonomic shifts, and cascade effects of substrate availability cause replacement of functional guilds and functional changes within taxa. PMID:25918393

  13. Metabolic and trophic interactions modulate methane production by Arctic peat microbiota in response to warming

    PubMed Central

    Tveit, Alexander Tøsdal; Urich, Tim; Frenzel, Peter; Svenning, Mette Marianne

    2015-01-01

    Arctic permafrost soils store large amounts of soil organic carbon (SOC) that could be released into the atmosphere as methane (CH4) in a future warmer climate. How warming affects the complex microbial network decomposing SOC is not understood. We studied CH4 production of Arctic peat soil microbiota in anoxic microcosms over a temperature gradient from 1 to 30 °C, combining metatranscriptomic, metagenomic, and targeted metabolic profiling. The CH4 production rate at 4 °C was 25% of that at 25 °C and increased rapidly with temperature, driven by fast adaptations of microbial community structure, metabolic network of SOC decomposition, and trophic interactions. Below 7 °C, syntrophic propionate oxidation was the rate-limiting step for CH4 production; above this threshold temperature, polysaccharide hydrolysis became rate limiting. This change was associated with a shift within the functional guild for syntrophic propionate oxidation, with Firmicutes being replaced by Bacteroidetes. Correspondingly, there was a shift from the formate- and H2-using Methanobacteriales to Methanomicrobiales and from the acetotrophic Methanosarcinaceae to Methanosaetaceae. Methanogenesis from methylamines, probably stemming from degradation of bacterial cells, became more important with increasing temperature and corresponded with an increased relative abundance of predatory protists of the phylum Cercozoa. We concluded that Arctic peat microbiota responds rapidly to increased temperatures by modulating metabolic and trophic interactions so that CH4 is always highly produced: The microbial community adapts through taxonomic shifts, and cascade effects of substrate availability cause replacement of functional guilds and functional changes within taxa. PMID:25918393

  14. The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves

    NASA Astrophysics Data System (ADS)

    Zhang, Jinlun; Ashjian, Carin; Campbell, Robert; Hill, Victoria; Spitz, Yvette H.; Steele, Michael

    2014-01-01

    A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing summer

  15. Synthesis of integrated primary production in the Arctic Ocean: II. In situ and remotely sensed estimates

    NASA Astrophysics Data System (ADS)

    Hill, Victoria J.; Matrai, Patricia A.; Olson, Elise; Suttles, S.; Steele, Mike; Codispoti, L. A.; Zimmerman, Richard C.

    2013-03-01

    Recent warming of surface waters, accompanied by reduced ice thickness and extent may have significant consequences for climate-driven changes of primary production (PP) in the Arctic Ocean (AO). However, it has been difficult to obtain a robust benchmark estimate of pan-Arctic PP necessary for evaluating change. This paper provides an estimate of pan-Arctic PP prior to significant warming from a synthetic analysis of the ARCSS-PP database of in situ measurements collected from 1954 to 2007 and estimates derived from satellite-based observations from 1998 to 2007. Vertical profiles of in situ chlorophyll a (Chl a) and PP revealed persistent subsurface peaks in biomass and PP throughout the AO during most of the summer period. This was contradictory with the commonly assumed exponential decrease in PP with depth on which prior satellite-derived estimates were based. As remotely sensed Chl a was not a good predictor of integrated water column Chl a, accurate satellite-based modeling of vertically integrated primary production (IPPsat), requires knowledge of the subsurface distribution of phytoplankton, coincident with the remotely sensed ocean color measurements. We developed an alternative approach to modeling PP from satellite observations by incorporating climatological information on the depths of the euphotic zone and the mixed layer that control the distribution of phytoplankton that significantly improved the fidelity of satellite derived PP to in situ observations. The annual IPP of the Arctic Ocean combining both in situ and satellite based estimates was calculated here to be a minimum of 466 ± 94 Tg C yr-1 and a maximum of 993 ± 94 Tg C yr-1, when corrected for subsurface production. Inflow shelf seas account for 75% of annual IPP, while the central basin and Beaufort northern sea were the regions with the lowest annual integrated productivity, due to persistently stratified, oligotrophic and ice-covered conditions. Although the expansion of summertime

  16. Production and Cycling of Methylated Mercury Species in Arctic Marine Waters

    NASA Astrophysics Data System (ADS)

    Lehnherr, I.; St. Louis, V. L.; Hintelmann, H.

    2009-12-01

    Monomethyl mercury (MMHg), a vertebrate neurotoxin which bioaccumulates through foodwebs, is found in some Arctic marine mammals at levels that may be harmful to northern peoples consuming them as food. Unfortunately, sources of MMHg to polar marine food webs remain unknown, in part due to the complex nature of Hg cycling in polar marine waters. Since 2005, we have been sampling the marine waters of the Canadian Arctic Archipelago from the Canadian Coast Guard research icebreaker CCGS Amundsen. Early results demonstrated that elevated concentrations of both MMHg and dimethyl mercury (DMHg, a toxic, gaseous Hg species) are found in sub-surface Arctic marine waters (89±36 pg L-1 and 73±37 pg L-1, respectively) despite low total Hg (THg) concentrations (290±220 pg L-1), suggesting an internal source of methylated Hg. We tested the hypothesis that methylated Hg species are produced directly in the marine water column using stable-isotope Hg tracers. Seawater samples were amended with 198Hg(II) and incubated for 0, 8, 16 or 24 hours to measure the production of MM198Hg, DM198Hg and gaseous elemental 198Hg(0) (GEM) over time. A second tracer, MM199Hg, was also added to quantify MMHg methylation (formation of DM199Hg), demethylation (loss of MM199Hg) and reduction (formation of 199Hg(0)). Preliminary analysis of the data indicates that Hg(II) is methylated in polar marine waters to form both MMHg (first order rate-constant km1 ~6x10-4 d-1) and DMHg (km2 ~5x10-6 d-1). We also found that DMHg production from MMHg is ~50x faster than with Hg(II) as the substrate. Furthermore, at a small number of sites, we measured methylation rates that were elevated by almost a full order of magnitude compared to the average, suggesting that methylation hotspots may exist in Arctic marine waters. However, during the less productive fall season when the CCGS Amundsen cruises were conducted, demethylation of MMHg generally appears to dominate in the water column and can occur via a number

  17. Influences of seasonality, geomorphology, and hydrology on primary production and respiration in Arctic stream ecosystems

    NASA Astrophysics Data System (ADS)

    Herstand, M. R.; Bowden, W. B.; Gooseff, M. N.; Whittinghill, K. A.; Wlostowski, A. N.; Wollheim, W. M.

    2011-12-01

    Stream ecosystem processes in the Arctic are poorly understood in the spring and fall 'shoulder' seasons. We hypothesize that seasonal changes in solar radiation, hydrologic conditions, and landscape inputs are all reflected in the seasonal patterns of Gross Primary Productivity (GPP) and Community Respiration (CR). We continuously monitored the GPP and CR of three streams with different geomorphic characteristics (alluvial lake inlet, alluvial lake outlet, and beaded peat) near Toolik Lake Field Station, Alaska from breakup to freeze-up during 2011. We used open-system whole stream metabolism (WSM) methods, with dissolved oxygen estimates every five minutes. Dissolved and particulate nutrient chemistry, benthic chlorophyll, and nutrient uptake rates from solute injections were also measured across the seasons, and had correlations with GPP and CR. The fall freeze-up season was especially productive, as the well-developed benthic community responded to either lower flows (preventing sloughing) and/or increasing dissolved nutrient loads during landscape plant senescence. Storm events and high flow conditions (observed throughout seasons) decreased the GPP:CR ratio. Average monthly air temperatures have increased on the North Slope, especially during the shoulder seasons, increasing the duration of the ice-free stream season. Increasing the fall shoulder season may increase the annual stream GPP and nutrient uptake, with uncertain impacts on nutrient loading to the Arctic Ocean.

  18. Estimation of water quality and plant primary production in Arctic wetlands using ground based spectrometry

    NASA Astrophysics Data System (ADS)

    Andresen, C.; Lougheed, V.; Tweedie, C.

    2010-12-01

    Wetlands represent a significant portion of the Arctic tundra landscape, which is experiencing warming at an unprecedented rate. Understanding of primary production in these ecosystems is essential for assessing carbon fluxes and climate change effects. Remote sensing techniques are known to be accurate and cost effective to monitor aquatic vegetation and water quality parameters; however, their utility in mapping these ecosystems is unknown. We used a handheld hyperspectral radiometer (Unispec, PP Systems) to measure reflectance across the visible and near-infrared spectrum (400-1100nm) of two predominant aquatic graminoid species (Carex aquatilis and Arctophila fulva) along an anthropogenic disturbance gradient in tundra ponds of Barrow, Alaska. Spectral measurements were validated with in situ biomass harvest and water quality monitoring (e.g DOC, nutrients, algal chlorophyll). Reflectance of the two plant species exhibited spectral differences in the near-infrared portion of the spectrum. These reflectance measurements were also associated with water quality and plant biomass. Future efforts will involve the extrapolation of these ground based observations to a regional level using airborne and satellite imagery. This study advances large scale quantification and monitoring of water quality and aquatic plant production in the Arctic tundra and aids understanding of anthropogenic and climate effects in this rapidly changing ecosystem.

  19. Observational determination of albedo decrease caused by vanishing Arctic sea ice.

    PubMed

    Pistone, Kristina; Eisenman, Ian; Ramanathan, V

    2014-03-01

    The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m(2) of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming. PMID:24550469

  20. Determining Regional Arctic Tundra Carbon Exchange: A Bottom-Up Approach

    NASA Technical Reports Server (NTRS)

    Huemmrich, Fred

    2006-01-01

    This viewgraph presentation reviews the carbon atmospheric exchange with Arctic tundra. In the Arctic the ecosystem has been a net carbon sink. The project investigates the question of how might climate warming effect high latitude ecosystems and the Earth ecosystems and how to measure the changes.

  1. The response of aboveground plant productivity to earlier snowmelt and summer warming in an Arctic ecosystem

    NASA Astrophysics Data System (ADS)

    Livensperger, C.; Steltzer, H.; Darrouzet-Nardi, A.; Sullivan, P.; Wallenstein, M. D.; Weintraub, M. N.

    2012-12-01

    Plant communities in the Arctic are undergoing changes in structure and function due to shifts in seasonality from changing winters and summer warming. These changes will impact biogeochemical cycling, surface energy balance, and functioning of vertebrate and invertebrate communities. To examine seasonal controls on aboveground net primary production (ANPP) in a moist acidic tundra ecosystem in northern Alaska, we shifted the growing season by accelerating snowmelt (using radiation absorbing shadecloth) and warming air and soil temperature (using 1 m2 open-top chambers), individually and in combination. After three years, we measured ANPP by harvesting up to 16 individual ramets, tillers and rhizomes for each of 7 plant species, including two deciduous shrubs, two graminoids, two evergreen shrubs and one forb during peak season. Our results show that ANPP per stem summed across the 7 species increased when snow melt occurred earlier. However, standing biomass, excluding current year growth, was also greater. The ratio of ANPP/standing biomass decreased in all treatments compared to the control. ANPP per unit standing biomass summed for the four shrub species decreases due to summer warming alone or in combination with early snowmelt; however early snowmelt alone did not lead to lower ANPP for the shrubs. ANPP per tiller or rhizome summed for the three herbaceous species increased in response to summer warming. Understanding the differential response of plants to changing seasonality will inform predictions of future Arctic plant community structure and function.

  2. Standing stocks, production, and respiration of phytoplankton and heterotrophic bacteria in the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.; Hill, Victoria; Cottrell, Matthew T.; Gradinger, Rolf; Malmstrom, Rex R.; Parker, Alexander

    2009-08-01

    Standing stocks and production rates for phytoplankton and heterotrophic bacteria were examined during four expeditions in the western Arctic Ocean (Chukchi Sea and Canada Basin) in the spring and summer of 2002 and 2004. Rates of primary production (PP) and bacterial production (BP) were higher in the summer than in spring and in shelf waters than in the basin. Most surprisingly, PP was 3-fold higher in 2004 than in 2002; ice-corrected rates were 1581 and 458 mg C m -2 d -1, respectively, for the entire region. The difference between years was mainly due to low ice coverage in the summer of 2004. The spatial and temporal variation in PP led to comparable variation in BP. Although temperature explained as much variability in BP as did PP or phytoplankton biomass, there was no relationship between temperature and bacterial growth rates above about 0 °C. The average ratio of BP to PP was 0.06 and 0.79 when ice-corrected PP rates were greater than and less than 100 mg C m -2 d -1, respectively; the overall average was 0.34. Bacteria accounted for a highly variable fraction of total respiration, from 3% to over 60% with a mean of 25%. Likewise, the fraction of PP consumed by bacterial respiration, when calculated from growth efficiency (average of 6.9%) and BP estimates, varied greatly over time and space (7% to >500%). The apparent uncoupling between respiration and PP has several implications for carbon export and storage in the western Arctic Ocean.

  3. Camera derived vegetation greenness index as proxy for gross primary production in a low Arctic wetland area

    NASA Astrophysics Data System (ADS)

    Westergaard-Nielsen, Andreas; Lund, Magnus; Hansen, Birger Ulf; Tamstorf, Mikkel Peter

    2013-12-01

    The Arctic is experiencing disproportionate warming relative to the global average, and the Arctic ecosystems are as a result undergoing considerable changes. Continued monitoring of ecosystem productivity and phenology across temporal and spatial scales is a central part of assessing the magnitude of these changes. This study investigates the ability to use automatic digital camera images (DCIs) as proxy data for gross primary production (GPP) in a complex low Arctic wetland site. Vegetation greenness computed from DCIs was found to correlate significantly (R2 = 0.62, p < 0.001) with a normalized difference vegetation index (NDVI) product derived from the WorldView-2 satellite. An object-based classification based on a bi-temporal image composite was used to classify the study area into heath, copse, fen, and bedrock. Temporal evolution of vegetation greenness was evaluated and modeled with double sigmoid functions for each plant community. GPP at light saturation modeled from eddy covariance (EC) flux measurements were found to correlate significantly with vegetation greenness for all plant communities in the studied year (i.e., 2010), and the highest correlation was found between modeled fen greenness and GPP (R2 = 0.85, p < 0.001). Finally, greenness computed within modeled EC footprints were used to evaluate the influence of individual plant communities on the flux measurements. The study concludes that digital cameras may be used as a cost-effective proxy for potential GPP in remote Arctic regions.

  4. What determines the current presence or absence of permafrost in the Torneträsk region, a sub-arctic landscape in northern Sweden?

    PubMed

    Johansson, Margareta; Christensen, Torben R; Akerman, H Jonas; Callaghan, Terry V

    2006-06-01

    In a warming climate, permafrost is likely to be significantly reduced and eventually disappear from the sub-Arctic region. This will affect people at a range of scales, from locally by slumping of buildings and roads, to globally as melting of permafrost will most likely increase the emissions of the powerful greenhouse gas methane, which will further enhance global warming. In order to predict future changes in permafrost, it is crucial to understand what determines the presence or absence of permafrost under current climate conditions, to assess where permafrost is particularly vulnerable to climate change, and to identify where changes are already occurring. The Torneträsk region of northern sub-Arctic Sweden is one area where changes in permafrost have been recorded and where permafrost could be particularly vulnerable to any future climate changes. This paper therefore reviews the various physical, biological, and anthropogenic parameters that determine the presence or absence of permafrost in the Torneträsk region under current climate conditions, so that we can gain an understanding of its current vulnerability and potential future responses to climate change. A patchy permafrost distribution as found in the Torneträsk region is not random, but a consequence of site-specific factors that control the microclimate and hence the surface and subsurface temperature. It is also a product of past as well as current processes. In sub-Arctic areas such as northern Sweden, it is mainly the physical parameters, e.g., topography, soil type, and climate (in particular snow depth), that determine permafrost distribution. Even though humans have been present in the study area for centuries, their impacts on permafrost distribution can more or less be neglected at the catchment level. Because ongoing climate warming is projected to continue and lead to an increased snow cover, the permafrost in the region will most likely disappear within decades, at least at lower

  5. Isotopic insights into methane production, oxidation, and emissions in Arctic polygon tundra.

    PubMed

    Vaughn, Lydia J S; Conrad, Mark E; Bill, Markus; Torn, Margaret S

    2016-10-01

    Arctic wetlands are currently net sources of atmospheric CH4 . Due to their complex biogeochemical controls and high spatial and temporal variability, current net CH4 emissions and gross CH4 processes have been difficult to quantify, and their predicted responses to climate change remain uncertain. We investigated CH4 production, oxidation, and surface emissions in Arctic polygon tundra, across a wet-to-dry permafrost degradation gradient from low-centered (intact) to flat- and high-centered (degraded) polygons. From 3 microtopographic positions (polygon centers, rims, and troughs) along the permafrost degradation gradient, we measured surface CH4 and CO2 fluxes, concentrations and stable isotope compositions of CH4 and DIC at three depths in the soil, and soil moisture and temperature. More degraded sites had lower CH4 emissions, a different primary methanogenic pathway, and greater CH4 oxidation than did intact permafrost sites, to a greater degree than soil moisture or temperature could explain. Surface CH4 flux decreased from 64 nmol m(-2)  s(-1) in intact polygons to 7 nmol m(-2)  s(-1) in degraded polygons, and stable isotope signatures of CH4 and DIC showed that acetate cleavage dominated CH4 production in low-centered polygons, while CO2 reduction was the primary pathway in degraded polygons. We see evidence that differences in water flow and vegetation between intact and degraded polygons contributed to these observations. In contrast to many previous studies, these findings document a mechanism whereby permafrost degradation can lead to local decreases in tundra CH4 emissions. PMID:26990225

  6. Spectral determination of concentrations of functionally diverse pigments in increasingly complex arctic tundra canopies.

    PubMed

    Boelman, Natalie T; Magney, Troy S; Logan, Barry A; Griffin, Kevin L; Eitel, Jan U H; Greaves, Heather; Prager, Case M; Vierling, Lee A

    2016-09-01

    As the Arctic warms, tundra vegetation is becoming taller and more structurally complex, as tall deciduous shrubs become increasingly dominant. Emerging studies reveal that shrubs exhibit photosynthetic resource partitioning, akin to forests, that may need accounting for in the "big leaf" net ecosystem exchange models. We conducted a lab experiment on sun and shade leaves from S. pulchra shrubs to determine the influence of both constitutive (slowly changing bulk carotenoid and chlorophyll pools) and facultative (rapidly changing xanthophyll cycle) pigment pools on a suite of spectral vegetation indices, to devise a rapid means of estimating within canopy resource partitioning. We found that: (1) the PRI of dark-adapted shade leaves (PRIo) was double that of sun leaves, and that PRIo was sensitive to variation among sun and shade leaves in both xanthophyll cycle pool size (V + A + Z) (r (2) = 0.59) and Chla/b (r (2) = 0.64); (2) A corrected PRI (difference between dark and illuminated leaves, ΔPRI) was more sensitive to variation among sun and shade leaves in changes to the epoxidation state of their xanthophyll cycle pigments (dEPS) (r (2) = 0.78, RMSE = 0.007) compared to the uncorrected PRI of illuminated leaves (PRI) (r (2) = 0.34, RMSE = 0.02); and (3) the SR680 index was correlated with each of (V + A + Z), lutein, bulk carotenoids, (V + A + Z)/(Chla + b), and Chla/b (r (2) range = 0.52-0.69). We suggest that ΔPRI be employed as a proxy for facultative pigment dynamics, and the SR680 for the estimation of constitutive pigment pools. We contribute the first Arctic-specific information on disentangling PRI-pigment relationships, and offer insight into how spectral indices can assess resource partitioning within shrub tundra canopies. PMID:27193900

  7. Permafrost thawing in organic Arctic soils accelerated by ground heat production

    NASA Astrophysics Data System (ADS)

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Elberling, Bo

    2015-06-01

    Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change. The accompanying heat production from microbial metabolism of organic material has been recognized as a potential positive-feedback mechanism that would enhance permafrost thawing and the release of carbon. This internal heat production is poorly understood, however, and the strength of this effect remains unclear. Here, we have quantified the variability of heat production in contrasting organic permafrost soils across Greenland and tested the hypothesis that these soils produce enough heat to reach a tipping point after which internal heat production can accelerate the decomposition processes. Results show that the impact of climate changes on natural organic soils can be accelerated by microbial heat production with crucial implications for the amounts of carbon being decomposed. The same is shown to be true for organic middens with the risk of losing unique evidence of early human presence in the Arctic.

  8. A Method for Continuous (239)Pu Determinations in Arctic and Antarctic Ice Cores.

    PubMed

    Arienzo, M M; McConnell, J R; Chellman, N; Criscitiello, A S; Curran, M; Fritzsche, D; Kipfstuhl, S; Mulvaney, R; Nolan, M; Opel, T; Sigl, M; Steffensen, J P

    2016-07-01

    Atmospheric nuclear weapons testing (NWT) resulted in the injection of plutonium (Pu) into the atmosphere and subsequent global deposition. We present a new method for continuous semiquantitative measurement of (239)Pu in ice cores, which was used to develop annual records of fallout from NWT in ten ice cores from Greenland and Antarctica. The (239)Pu was measured directly using an inductively coupled plasma-sector field mass spectrometer, thereby reducing analysis time and increasing depth-resolution with respect to previous methods. To validate this method, we compared our one year averaged results to published (239)Pu records and other records of NWT. The (239)Pu profiles from the Arctic ice cores reflected global trends in NWT and were in agreement with discrete Pu profiles from lower latitude ice cores. The (239)Pu measurements in the Antarctic ice cores tracked low latitude NWT, consistent with previously published discrete records from Antarctica. Advantages of the continuous (239)Pu measurement method are (1) reduced sample preparation and analysis time; (2) no requirement for additional ice samples for NWT fallout determinations; (3) measurements are exactly coregistered with all other chemical, elemental, isotopic, and gas measurements from the continuous analytical system; and (4) the long half-life means the (239)Pu record is stable through time. PMID:27244483

  9. Production rate estimation of mycosporine-like amino acids in two Arctic melt ponds by stable isotope probing with NAH(13) CO3.

    PubMed

    Ha, Sun-Yong; Min, Jun-Oh; Joo, Hyun Min; Chung, Kyung Ho; Shin, Kyung-Hoon; Yang, EunJin; Kang, Sung-Ho

    2014-10-01

    The net carbon uptake rate and net production rate of mycosporine-like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a (13) C stable isotope tracer technique. The Research Vessel Araon visited ice-covered western-central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.24 mg C · m(-3) · h(-1) (SD = ±1.12 mg C · m(-3) · h(-1) ), while that in the open MP was 1.3 mg C · m(-3) · h(-1) (SD = ±0.05 mg C · m(-3) · h(-1) ). The net production rate of total MAAs in incubated PC bottles was highest (1.44 (SD = ±0.24) ng C · L(-1) · h(-1) ) in the open MP and lowest (0.05 (SD = ±0.003) ng C · L(-1) · h(-1) ) in the closed MP. The net production rate of shinorine and palythine in incubated PC bottles at the open MP presented significantly high values 0.76 (SD = ±0.12) ng C · L(-1) · h(-1) and 0.53 (SD = ±0.06) ng C · L(-1) · h(-1) . Our results showed that high net production rate of MAAs in the open MP was enhanced by a combination of osmotic and UVR stress and that in situ net production rates of individual MAA can be determined using (13) C tracer in MPs in Arctic sea ice. PMID:26988644

  10. Arctic hydroclimatology

    NASA Astrophysics Data System (ADS)

    Cherry, Jessica Ellen

    Arctic air temperature, precipitation, ground temperature, river runoff, clouds, and radiation are all changing quickly in a warming climate. Interactions and feedbacks between these features are not well understood. In particular, the relative role of local climate processes and large-scale ocean-atmosphere dynamics in driving observed Arctic changes is difficult to ascertain because of the sparsity of observations, inaccuracy of those that do exist, biases in global circulation models and analyses, and fundamental physics of the Arctic region. Four studies of Arctic hydroclimatology herein attempt to overcome these challenges. The first study, analysis of the Lena river basin hydroclimatology, shows canonical acceleration of the hydrologic cycle and amplification of global warming. Winter and spring are warming and increased frozen precipitation is contributing to permafrost melting by increasing soil insulation. Increasing runoff and soil moisture is leading to increasing evapotranspiration and changes in clouds. Changes in clouds are cooling summer days but warming summer nights, melting additional permafrost. Model simulations suggests that a deepening active layer will lead to an increasingly wet Arctic. The second two studies describe the development of the Pan-Arctic Snowfall Reconstruction (PASR). This product addresses the problem of cold season precipitation gauge biases for 1940-1999. The NASA Interannual-to-Seasonal Prediction Project Catchment-based Land Surface Model is used to reconstruct solid precipitation from observed snow depth and surface air temperatures. Error estimation is done via controlled simulations at Reynolds Creek Experimental Watershed, in Idaho. The method is then applied to stations in the pan-Arctic hydrological catchment. Comparison with existing products suggests that the PASR is a better estimate of actual snowfall for hydroclimatological studies. The final chapter is a case study on hydroclimatological variability driven by

  11. Global and regional drivers of nutrient supply, primary production and CO2 drawdown in the changing Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Éric; Anderson, Leif G.; Matrai, Patricia; Coupel, Pierre; Bélanger, Simon; Michel, Christine; Reigstad, Marit

    2015-12-01

    The main environmental factors driving spatial patterns, variability and change in primary production (PP) in the Arctic Ocean are reviewed. While instantaneous PP rates are predominantly influenced by the local factors affecting light penetration through clouds, sea ice and water, net PP (NPP) at the annual scale is conditioned by a hierarchy of remote and local processes that affect nutrient supply and light availability in general. Nutrient supply sets spatial differences in realized or potential trophic status (i.e. oligotrophic or eutrophic), whereas light availability modulates PP within each regime. Horizontal nutrient supply through Atlantic and Pacific ocean gateways differ markedly, which is explained by their position at opposite ends of the global meridional overturning circulation and imbalanced nitrogen (N) cycling in the Pacific sector. Nutrient supply by rivers is locally important, but does not appear to sustain a major portion of overall pan-Arctic NPP so far. Horizontal nutrient inputs to the surface Arctic Ocean are eventually transferred to the halocline through winter convection and the decomposition of settling organic matter. The subsequent re-injection of these nutrients to the euphotic zone varies by two orders of magnitude across sectors, depending on the strength and persistence of the vertical stratification. Such differences in nutrient delivery are commensurate with those of PP and NPP rates. Widespread N deficiency in surface waters fosters the occurrence and seasonal persistence of subsurface layers of maximum chlorophyll a (SCM) and phytoplankton carbon biomass in several sectors. The contribution of these layers to NPP is possibly higher in the Arctic than in thermally-stratified waters of the subtropical gyres due to a combination of extreme acclimation to low light and a shallow nitracline in the former. The overall impacts of SCM layers on biogeochemical fluxes remain to be quantified directly, both regionally and at the pan-Arctic

  12. Isolating the effects of storm events on arctic aquatic bacteria: temperature, nutrients, and community composition as controls on bacterial productivity

    PubMed Central

    Adams, Heather E.; Crump, Byron C.; Kling, George W.

    2015-01-01

    Storm events can pulse nutrients and carbon from soils and provide an important subsidy to food webs in oligotrophic streams and lakes. Bacterial nutrient limitation and the potential response of stream aquatic bacteria to storm events was investigated in arctic tundra environments by manipulating both water temperature and inorganic nutrient concentrations in short (up to 4 days) and long duration (up to 2 weeks) laboratory mesocosm experiments. Inorganic N and P additions increased bacterial production (14C-labeled leucine uptake) up to seven times over controls, and warmer incubation temperatures increased the speed of this response to added nutrients. Bacterial cell numbers also increased in response to temperature and nutrient additions with cell-specific carbon uptake initially increasing and then declining after 2 days. Bacterial community composition (BCC; determined by means of 16S denaturing gradient gel electrophoresis fingerprinting) shifted rapidly in response to changes in incubation temperature and the addition of nutrients, within 2 days in some cases. While the bacteria in these habitats responded to nutrient additions with rapid changes in productivity and community composition, water temperature controlled the speed of the metabolic response and affected the resultant change in bacterial community structure, constraining the potential responses to pulsed nutrient subsidies associated with storm events. In all cases, at higher nutrient levels and temperatures the effect of initial BCC on bacterial activity was muted, suggesting a consistent, robust interaction of temperature, and nutrients controlling activity in these aquatic systems. PMID:25873916

  13. Algal pigments record shifts in dominant primary productivity through the Holocene in an arctic lake

    NASA Astrophysics Data System (ADS)

    Florian, C.; Miller, G. H.; Fogel, M. L.

    2011-12-01

    The character and magnitude of primary productivity in arctic lakes is largely controlled by climate. Organic compounds derived from pigments and preserved in lake sediments allow reconstruction of past abundances of algae that do not leave silicious microfossils. Fossil algal pigments are abundant in lake sediment and can be accurately quantified using High Pressure Liquid Chromatography (HPLC). Several groups of algae produce unique pigments that can be used to reconstruct their past abundance. In Qivitu Highlands Lake, eastern central Baffin Island, the ratio of pigments diatoxantin and lutein exhibits coherent changes through the Holocene. Diatoxanthin is produced by diatoms and chrysophytes, whereas lutein is produced by green algae and higher plants. Because these pigments are the dominant carotenoids in the sediment, they serve as proxies for the dominant group of primary producers. During the Holocene Thermal Maximum and the past century, lutein is much more abundant than diatoxanthin. During Neoglacial cooling and into the Little Ice Age, diatoxanthin becomes the dominant carotenoid. This shift reveals that there was a change in not only the magnitude of algal production, but also the most abundant type. The adaptation of aquatic algal assemblages to changing climate suggests that gross changes in primary productivity may not be suitable to track the abundance of one type of algal microfossil (such as diatoms) without considering the other algal groups. Higher plants also produce lutein, and its abundance is additionally influenced by the presence of terrestrial organic matter as well as aquatic macrophyte plants. We hypothesize that the prevalence of lutein during warm summers is due to a longer ice-free season, allowing the development of a greater biomass of green algae and macrophyte plants as well as possible increases of terrestrial higher plant communities. This is part of a larger study where the lutein to diatoxanthin ratio is compared to organic

  14. Contrasts in Sea Ice Deformation and Production in the Arctic Seasonal and Perennial Ice Zones

    NASA Technical Reports Server (NTRS)

    Kwok, K.

    2006-01-01

    Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. Three-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the midwinter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is seen in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m): this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. Uncertainties in these estimates are discussed. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice. Divergence is shown to be negligibly correlated to cyclonic motion in summer and winter in both ice zones.

  15. Contrasts in Sea Ice Formation and Production in the Arctic Seasonal and Perennial Ice Zones

    NASA Technical Reports Server (NTRS)

    Kwok, R.

    2006-01-01

    Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. 3-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the mid-winter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m) - this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by: local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and, the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice.

  16. Benthic macrofauna and productivity regimes in the Barents Sea — Ecological implications in a changing Arctic

    NASA Astrophysics Data System (ADS)

    Cochrane, Sabine K. J.; Denisenko, Stanislav G.; Renaud, Paul E.; Emblow, Christopher S.; Ambrose, William G., Jr.; Ellingsen, Ingrid H.; Skarðhamar, Jofrid

    2009-04-01

    Benthic faunal assemblages were analysed from 47 stations in the central and southern parts of the Barents Sea, together with sedimentary and water column parameters, daily ice records and modelled integrated primary productivity. Sampling spanned areas influenced by Atlantic Water (AW) to those lying under Arctic Water (ArW), and included stations with mixed water masses. Ice cover suppressed water column productivity in the northern areas. Three main faunal groups were identified, based on similarity of numerical faunal composition. The northern and southern faunal groups were separated by the northernmost penetration of AW in the bottom water and the third group, the Hopen group, was influenced by modified bank water. Faunal abundances were significantly higher within the southern faunal group relative to the northern group, but the numbers of taxa present were similar. The particularly rich fauna of the Hopen group reflected sediment heterogeneity and tight pelagic-benthic coupling. These results suggest that a retreat and thinning of the ice cover in the Barents Sea likely will result in the northern parts of the Barents Sea becoming more Atlantic in character, with a higher productivity at the sea floor.

  17. Quantifying Sea Ice Advection Through Key "Gates" in the Arctic Using the Sea Ice Motion and Age Data Products at the University of Colorado, Boulder With Applications to Studying Changes in the Arctic Ice Pack.

    NASA Astrophysics Data System (ADS)

    Tooth, M.; Tschudi, M. A.

    2015-12-01

    The past several decades have seen an alarming decline in sea ice extent, and a trend toward thinner, first-year ice throughout the Arctic. This younger ice has a lower probability of surviving the next melt season, and features different surface properties than multi-year ice floes typically possess. Through the combination of satellite passive microwave observations and buoy data, the motion and age of the ice pack in the Arctic are tracked and analyzed using datasets produced at the University of Colorado, Boulder that are archived at the National Snow and Ice Data Center. The ice motion product is produced daily from 1978 to the present, and the weekly age data span from 1985 onward. Using these products, the advection of first-year and multi-year ice is tracked through several key ice "gates" throughout the Arctic on relatively short time scales. Understanding the "sinks" that sea ice travels to and melts in will provide a more complete picture of the underlying causes in the decline in sea ice extent and volume in the Arctic. Through tracking the trajectory and locations of ice parcels in our ice motion product, we can also use other co-located data products to assess the impact of radiative and other climate component forcing on the Arctic ice pack.

  18. The sensitivity of Arctic sea ice production to shelf flooding during the early Holocene: a modelling study

    NASA Astrophysics Data System (ADS)

    Blaschek, M.; Renssen, H.

    2012-04-01

    During the last deglaciation, the global sea-level started rising, changing the coastlines from an early Holocene stand (40 m lower than today at approximately 10 kyr BP, Siddall et al., 2003) to modern day coastlines. Proxy evidence shows that this transgression occurred non-uniformly over the globe. For instance, Bauch et al. (2001) report for the Laptev Sea (Arctic Ocean), that the modern coastline was only established at 5 kyr BP after a fast transgression from the early Holocene, leading to a flooding of the extensive shelf area. This shelf area is presently regarded to be an important production zone of Arctic sea ice, playing an important role in the dynamics of sea ice in the Arctic, as well as its export to the Nordic Seas along the East Greenland Current (EGC). Through this sea ice export, changes in the Laptev Sea shelf area during the Holocene could potentially have had a substantial impact on the sea surface conditions of the EGC, and the Denmark Strait, which is known to be sensitive to sea ice. This is consistent with a rapid increase in sea ice export through the EGC around 5 kyr BP as reported by Jennings et al. (2002). In this study we investigate the impact of this Arctic shelf flooding on sea ice production in the Holocene, and on the climate of the Nordic Seas in the LOVECLIM1.2 global ocean-atmosphere-vegetation model. We present results of several experiments in which we study the sensitivity of Arctic sea ice production to various Arctic shelf areas under early Holocene conditions (9 kyr BP). We approach this by changing the land-sea mask to represent different lower-than-present sea-level coastlines. For example, we perform experiments with the Last Glacial Maximum (LGM) land-sea mask, representing a lowering of the sea-level by 120 m, while keeping other forcings at 9 kyr BP. A further step is to modify selected areas in the Arctic, such as the Laptev Sea area, to examine the importance of different areas. Our results help to explain long

  19. Determining the Diversity and Species Abundance Patterns in Arctic Soils using Rational Methods for Exploring Microbial Diversity

    NASA Astrophysics Data System (ADS)

    Ovreas, L.; Quince, C.; Sloan, W.; Lanzen, A.; Davenport, R.; Green, J.; Coulson, S.; Curtis, T.

    2012-12-01

    Arctic microbial soil communities are intrinsically interesting and poorly characterised. We have inferred the diversity and species abundance distribution of 6 Arctic soils: new and mature soil at the foot of a receding glacier, Arctic Semi Desert, the foot of bird cliffs and soil underlying Arctic Tundra Heath: all near Ny-Ålesund, Spitsbergen. Diversity, distribution and sample sizes were estimated using the rational method of Quince et al., (Isme Journal 2 2008:997-1006) to determine the most plausible underlying species abundance distribution. A log-normal species abundance curve was found to give a slightly better fit than an inverse Gaussian curve if, and only if, sequencing error was removed. The median estimates of diversity of operational taxonomic units (at the 3% level) were 3600-5600 (lognormal assumed) and 2825-4100 (inverse Gaussian assumed). The nature and origins of species abundance distributions are poorly understood but may yet be grasped by observing and analysing such distributions in the microbial world. The sample size required to observe the distribution (by sequencing 90% of the taxa) varied between ~ 106 and ~105 for the lognormal and inverse Gaussian respectively. We infer that between 5 and 50 GB of sequencing would be required to capture 90% or the metagenome. Though a principle components analysis clearly divided the sites into three groups there was a high (20-45%) degree of overlap in between locations irrespective of geographical proximity. Interestingly, the nearest relatives of the most abundant taxa at a number of most sites were of alpine or polar origin. Samples plotted on first two principal components together with arbitrary discriminatory OTUs

  20. A ten-year history of the demography and productivity of an Arctic wolf pack

    USGS Publications Warehouse

    Mech, L.D.

    1995-01-01

    A pack of two to eight adult wolves (Canis lupus arctos) and their pups was observed during ten summers (1986-95) on Ellesmere Island, Northwest Territories, Canada. The author habituated the wolf pack to his presence in the first summer and reinforced the habituation each summer thereafter. The first alpha female produced four to six pups each year between 1986 and 1989. However, her daughter, who succeeded her as the alpha female, produced only one to three pups each year between 1990 and 1992 and in 1994, and apparently did not whelp in 1993 or in 1995. The tenure of the first alpha male was at least two years, and his successor was alpha male for the remaining eight years of the study. The wolf pack was characterized by highly variable annual productivity. The second alpha male-and-female breeding pair likely was an older brother and a younger sister. Early survival of wolf pups was high and constant, with all pups surviving through August of their first year. The pack's demography was consistent with what is known for wolf packs in other regions of North America, but its productivity was more typical of arctic packs.

  1. A pan-Arctic synthesis of CH4 and CO2 production from anoxic soil incubations

    USGS Publications Warehouse

    Treat, C.C.; Natali, S.M.; Ernakovich, Jessica; Iverson, Colleen M.; Lupasco, Massimo; McGuire, Anthony; Norby, Richard J.; Roy Chowdhury, Taniya; Richter, Andreas; Šantrůčková, Hana; Schädel, C.; Schuur, Edward A.G.; Sloan, Victoria L.; Turetsky, Merritt R.; Waldrop, Mark P.

    2015-01-01

    Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH4) and carbon dioxide (CO2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO2 and CH4 production and compare the relative importance of landscape-level factors (e.g., vegetation type and landscape position), soil properties (e.g., pH, depth, and soil type), and soil environmental conditions (e.g., temperature and relative water table position). We found fivefold higher maximum CH4 production per gram soil carbon from organic soils than mineral soils. Maximum CH4 production from soils in the active layer (ground that thaws and refreezes annually) was nearly four times that of permafrost per gram soil carbon, and CH4 production per gram soil carbon was two times greater from sites without permafrost than sites with permafrost. Maximum CH4 and median anaerobic CO2 production decreased with depth, while CO2:CH4 production increased with depth. Maximum CH4 production was highest in soils with herbaceous vegetation and soils that were either consistently or periodically inundated. This synthesis identifies the need to consider biome, landscape position, and vascular/moss vegetation types when modeling CH4 production in permafrost ecosystems and suggests the need for longer-term anaerobic incubations to fully capture CH4 dynamics. Our results demonstrate that as climate warms in arctic and boreal regions, rates of anaerobic CO2 and CH4 production will increase, not only as a result of increased temperature, but also from shifts in vegetation and increased

  2. The fate of production in the central Arctic Ocean - top-down regulation by zooplankton expatriates?

    NASA Astrophysics Data System (ADS)

    Olli, Kalle; Wassmann, Paul; Reigstad, Marit; Ratkova, Tatjana N.; Arashkevich, Elena; Pasternak, Anna; Matrai, Patricia A.; Knulst, Johan; Tranvik, Lars; Klais, Riina; Jacobsen, A.

    2007-01-01

    We estimated primary and bacterial production, mineral nutrients, suspended chlorophyll a (Chl), particulate organic carbon (POC) and nitrogen (PON), abundance of planktonic organisms, mesozooplankton fecal pellet production, and the vertical flux of organic particles of the central Arctic Ocean (Amundsen basin, 89-88° N) during a 3 week quasi-Lagrangian ice drift experiment at the peak of the productive season (August 2001). A visual estimate of ≈15% ice-free surface, plus numerous melt ponds on ice sheets, supported a planktonic particulate primary production of 50-150 mg C m -2 d -1 (mean 93 mg C m -2 d -1, n = 7), mostly confined to the upper 10 m of the nutrient replete water column. The surface mixed layer was separated from the rest of the water column by a strong halocline at 20 m depth. Phototrophic biomass was low, generally 0.03-0.3 mg Chl m -3 in the upper 20 m and <0.02 mg Chl m -3 below, dominated by various flagellates, dinoflagellates and diatoms. Bacterial abundance (typically 3.7-5.3 × 10 5, mean 4.1 × 10 5 cells ml -1 in the upper 20 m and 1.3-3.7 × 10 5, mean 1.9 × 10 5 cells ml -1 below) and Chl concentrations were closely correlated ( r = 0.75). Mineral nutrients (3 μmol NO 3 l -1, 0.45 μmol PO 4 l -1, 4-5 μmol SiO 4 l -1) were probably not limiting the primary production in the upper layer. Suspended POC concentration was ∼30-105 (mean 53) mg C m -3 and PON ∼5.4-14.9 (mean 8.2) mg N m -3 with no clear vertical trend. The vertical flux of POC in the upper 30-100 m water column was ∼37-92 (mean 55) mg C m -2 d -1 without clear decrease with depth, and was quite similar at the six investigated stations. The mesozooplankton biomass (≈2 g DW m -2, mostly in the upper 50 m water column) was dominated by adult females of the large calanoid copepods Calanus hyperboreus and Calanus glacialis (≈1.6 g DW m -2). The grazing of these copepods (estimated via fecal pellet production rates) was ≈15 mg C m -2 d -1, being on the order of

  3. Simulating net ecosystem productivity and the sensitivity of a sub-arctic boreal forest ecosystem

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Harazono, Y.; Kim, Y.; Tanaka, N.

    2005-12-01

    BIOME-BGC was used to examine how air temperature and precipitation affect NEP in a sub-arctic black spruce forest. The model was tuned using data from the eddy correlation measurement site in UAF black spruce forest during 2003 and 2004. The climate dataset of Fairbanks airport between 1949 and 2004 was used for the model spin-up. The model almost reproduced the observed NEE, in which climate in 2003 was normal and that in 2004 was drought in summer. The model, however, failed to simulate the late winter NEE, during which obvious daytime uptake were observed under extreme low temperature. Annual simulation of GPP and ecosystem respiration was 2.2 and 1.8 kg CO2 m-2 yr-1 in 2003 and 2.4 and 1.9 kg CO2 m-2 yr-1 in 2004. While warm growing season temperature enhanced the photosynthesis and respiration in 2004, significant drought in August 2004 were restricted both the photosynthesis and heterotrophic respiration. Simulated annual NEE was 0.2 kg CO2 m-2 yr-1 in 2003 and 0.3 kg CO2 m-2 yr-1 in 2004. The simulation explored the impact of seasonal warmer (+5oC), wetter (120% of precipitation) and drier (80% of precipitation) spells on net ecosystem productivity, comparing the long term Fairbanks weather between 1980 and 2000. Wetter condition in either season did not significantly affect annual NEP. While drought summer decreased annual NEP by 30% mainly due to reduction in GPP by 9%, low snowfall winter also reduced the annual NEP by 19%, in which low snow water brought drought stress in following summer and then suppressed both GPP to 93% and ecosystem respiration to 96%. Warmer summer and autumn decreased annual NEP to 37% and 65%. In this case, GPP did not increase and maintenance and heterotrophic respiration were enhanced to 120% and 126%, respectively, in warmer summer and 103% and 107%, respectively, in warmer autumn. The simulation unambiguously showed productivity of the sub-arctic boreal forest was significantly sensitive to warmer temperature in summer and

  4. Analysis of Crude Oil Production in the Arctic National Wildlife Refuge

    EIA Publications

    2008-01-01

    This report responds to a request from Senator Ted Stevens that the Energy Information Administration provide an assessment of federal oil and natural gas leasing in the coastal plain of the Arctic National Wildlife Refuge (ANWR) in Alaska.

  5. Temperature sensitivity of stream gross primary production and respiration from the tropics to the arctic

    NASA Astrophysics Data System (ADS)

    Song, C.; Argerich, A.; Baker, C.; Bowden, W. B.; Dodds, W. K.; Douglas, M.; Farrell, K.; Flinn, M. B.; Garcia, E.; Gido, K. B.; Harms, T.; Jones, J.; Koenig, L.; Kominoski, J. S.; McDonald, K. S.; McDowell, W. H.; McMaster, D.; Parker, S.; Rosemond, A.; Rüegg, J.; Sheehan, K.; Trentman, M. T.; Wollheim, W. M.; Ballantyne, F.

    2015-12-01

    Understanding the temperature dependence of gross primary production (GPP) and ecosystem respiration (ER) in streams is critical to predict the carbon balance in stream ecosystems under global warming. We collected dissolved oxygen (DO) concentration, photosynthetically active radiation (PAR), channel hydrology and geomorphology, and temperature from multiple locations throughout stream networks in seven sites across six biomes, specifically tropical forest, temperate deciduous forest, temperate coniferous forest, tallgrass prairie, boreal forest, and arctic tundra. We estimated the activation energy (Ea) of GPP and ER from diel changes in DO, temperature and PAR for each stream reach. We showed the relationship between Ea and environmental variables, such as temperature, light availability and discharge. In addition, we found that Ea of GPP and ER were highly variable from reach to reach within each biome. The estimated Ea of GPP and ER was generally higher than predicted by metabolic theory. Ea of GPP ranges from 20 to 140 KJ/mol and Ea of ER ranges from 50 to 150 KJ/mol. There was no consistent trend of larger Ea for GPP or ER. This suggests that the changes in carbon balance in streams caused directly by warming is likely to be site specific.

  6. Tracer-Based Determination of Vortex Descent in the 1999-2000 Arctic Winter

    NASA Technical Reports Server (NTRS)

    Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Hurst, Dale F.; Elkins, James W.; Schauffler, Sue M.; Atlas, Elliot L.; Herman, Robert L.; Webster, Christopher R.

    2001-01-01

    A detailed analysis of available in situ and remotely sensed N2O and CH4 data measured in the 1999-2000 winter Arctic vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences in potential temperature (theta) among balloon and aircraft vertical profiles (an average of 19-23 K on a given N2O or CH4 isopleth) indicated significant vortex inhomogeneity in late fall as compared with late winter profiles. A composite fall vortex profile was constructed for November 26, 1999, whose error bars encompassed the observed variability. High-latitude, extravortex profiles measured in different years and seasons revealed substantial variability in N2O and CH4 on theta surfaces, but all were clearly distinguishable from the first vortex profiles measured in late fall 1999. From these extravortex-vortex differences, we inferred descent prior to November 26: 397+/-15 K (1sigma) at 30 ppbv N2O and 640 ppbv CH4, and 28+/-13 K above 200 ppbv N2O and 1280 ppbv CH4. Changes in theta were determined on five N2O and CH4 isopleths from November 26 through March 12, and descent rates were calculated on each N2O isopleth for several time intervals. The maximum descent rates were seen between November 26 and January 27: 0.82+/-0.20 K/day averaged over 50-250 ppbv N2O. By late winter (February 26-March 12), the average rate had decreased to 0.10+/-0.25 K/day. Descent rates also decreased with increasing N2O; the winter average (November 26-March 5) descent rate varied from 0.75+/-0.10 K/day at 50 ppbv to 0.40+/-0.11 K/day at 250 ppbv. Comparison of these results with observations and models of descent in prior years showed very good overall agreement. Two models of the 1999-2000 vortex descent, SLIMCAT and REPROBUS, despite theta offsets with respect to observed profiles of up to 20 K on most tracer isopleths, produced descent rates that agreed very favorably with the inferred rates from observation.

  7. Measurements of condensation nuclei in the Airborne Arctic Stratospheric Expedition: Observations of particle production in the polar vortex

    SciTech Connect

    Wilson, J.C.; Stolzenburg, M.R. ); Clark, W.E. ); Loewenstein, M.; Ferry, G.V.; Chan, K.R. )

    1990-03-01

    The ER-2 Condensation Nucleus Counter (ER-2 CNC) was operated in the Airborne Arctic Stratospheric Expedition (AASE) in January and February 1989. The ER-2 CNC measures the mixing ratio of particles, CN, with diameters from approximately 0.02 {mu}m to approximately 1 {mu}m. The spatial distribution of CN in the Arctic polar vortex was found to resemble that measured in the Antarctic in the Spring of 1987. The vertical profile of CN in the vortex was lowered by subsidence. At altitudes above the minimum in the CN mixing ratio profile, CN mixing ratios correlated negatively with that of N{sub 2}O, demonstrating new particle production. CN serve as nuclei in the formation of Polar Stratospheric Clouds (PSC's) and the concentration of CN can affect PSC properties.

  8. Measurements of condensation nuclei in the Airborne Arctic Stratospheric Expedition - Observations of particle production in the polar vortex

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Stolzenburg, M. R.; Clark, W. E.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.

    1990-01-01

    The ER-2 Condensation Nucleus Counter (ER-2 CNC) was operated in the Airborne Arctic Stratospheric Expedition (AASE) in January and February 1989. The ER-2 CNC measures the mixing ratio of particles, CN, with diameters from approximately 0.02 to approximately 1 micron. The spatial distribution of CN in the Arctic polar vortex was found to resemble that measured in the Antarctic in the Spring of 1987. The vertical profile of CN in the vortex was lowered by subsidence. At altitudes above the minimum in the CN mixing ratio profile, CN mixing ratios correlated negatively with that of N2O, demonstrating new particle production. CN serve as nuclei in the formation of Polar Stratospheric Clouds (PSCs) and the concentration of CN can affect PSC properties.

  9. Arctic Economics Model

    Energy Science and Technology Software Center (ESTSC)

    1995-03-01

    AEM (Arctic Economics Model) for oil and gas was developed to provide an analytic framework for understanding the arctic area resources. It provides the capacity for integrating the resource and technology information gathered by the arctic research and development (R&D) program, measuring the benefits of alternaive R&D programs, and providing updated estimates of the future oil and gas potential from arctic areas. AEM enables the user to examine field or basin-level oil and gas recovery,more » costs, and economics. It provides a standard set of selected basin-specified input values or allows the user to input their own values. AEM consists of five integrated submodels: geologic/resource submodel, which distributes the arctic resource into 15 master regions, consisting of nine arctic offshore regions, three arctic onshore regions, and three souhtern Alaska (non-arctic) regions; technology submodel, which selects the most appropriate exploration and production structure (platform) for each arctic basin and water depth; oil and gas production submodel, which contains the relationship of per well recovery as a function of field size, production decline curves, and production decline curves by product; engineering costing and field development submodel, which develops the capital and operating costs associated with arctic oil and gas development; and the economics submodel, which captures the engineering costs and development timing and links these to oil and gas prices, corporate taxes and tax credits, depreciation, and timing of investment. AEM provides measures of producible oil and gas, costs, and ecomonic viability under alternative technology or financial conditions.« less

  10. Efficacy of calf:cow ratios for estimating calf production of arctic caribou

    USGS Publications Warehouse

    Cameron, R.D.; Griffith, B.; Parrett, L.S.; White, R.G.

    2013-01-01

    Caribou (Rangifer tarandus granti) calf:cow ratios (CCR) computed from composition counts obtained on arctic calving grounds are biased estimators of net calf production (NCP, the product of parturition rate and early calf survival) for sexually-mature females. Sexually-immature 2-year-old females, which are indistinguishable from sexually-mature females without calves, are included in the denominator, thereby biasing the calculated ratio low. This underestimate increases with the proportion of 2-year-old females in the population. We estimated the magnitude of this error with deterministic simulations under three scenarios of calf and yearling annual survival (respectively: low, 60 and 70%; medium, 70 and 80%; high, 80 and 90%) for five levels of unbiased NCP: 20, 40, 60, 80, and 100%. We assumed a survival rate of 90% for both 2-year-old and mature females. For each NCP, we computed numbers of 2-year-old females surviving annually and increased the denominator of CCR accordingly. We then calculated a series of hypothetical “observed” CCRs, which stabilized during the last 6 years of the simulations, and documented the degree to which each 6-year mean CCR differed from the corresponding NCP. For the three calf and yearling survival scenarios, proportional underestimates of NCP by CCR ranged 0.046–0.156, 0.058–0.187, and 0.071–0.216, respectively. Unfortunately, because parturition and survival rates are typically variable (i.e., age distribution is unstable), the magnitude of the error is not predictable without substantial supporting information. We recommend maintaining a sufficient sample of known-age radiocollared females in each herd and implementing a regular relocation schedule during the calving period to obtain unbiased estimates of both parturition rate and NCP.

  11. a New Japanese Project for Arctic Climate Change Research - Grene Arctic - (Invited)

    NASA Astrophysics Data System (ADS)

    Enomoto, H.

    2013-12-01

    A new Arctic Climate Change Research Project 'Rapid Change of the Arctic Climate System and its Global Influences' has started in 2011 for a five years project. GRENE-Arctic project is an initiative of Arctic study by more than 30 Japanese universities and institutes as the flame work of GRENE (Green Network of Excellence) of MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan). The GRENE-Arctic project set four strategic research targets: 1. Understanding the mechanism of warming amplification in the Arctic 2. Understanding the Arctic system for global climate and future change 3. Evaluation of the effects of Arctic change on weather in Japan, marine ecosystems and fisheries 4. Prediction of sea Ice distribution and Arctic sea routes This project aims to realize the strategic research targets by executing following studies: -Improvement of coupled general circulation models based on validations of the Arctic climate reproducibility and on mechanism analyses of the Arctic climate change and variability -The role of Arctic cryosphere in the global change -Change in terrestrial ecosystem of pan-Arctic and its effect on climate -Studies on greenhouse gas cycles in the Arctic and their responses to climate change -Atmospheric studies on Arctic change and its global impacts -Ecosystem studies of the Arctic ocean declining Sea ice -Projection of Arctic Sea ice responding to availability of Arctic sea route (* ** ***) *Changes in the Arctic ocean and mechanisms on catastrophic reduction of Arctic sea ice cover **Coordinated observational and modeling studies on the basic structure and variability of the Arctic sea ice-ocean system ***Sea ice prediction and construction of ice navigation support system for the Arctic sea route. Although GRENE Arctic project aims to product scientific contribution in a concentrated program during 2011-2016, Japanese Arctic research community established Japan Consortium for Arctic Environmental Research (JCAR) in May

  12. Phytoplankton Productivity in an Arctic Fjord (West Greenland): Estimating Electron Requirements for Carbon Fixation and Oxygen Production

    PubMed Central

    Hancke, Kasper; Dalsgaard, Tage; Sejr, Mikael Kristian; Markager, Stiig; Glud, Ronnie Nøhr

    2015-01-01

    Accurate quantification of pelagic primary production is essential for quantifying the marine carbon turnover and the energy supply to the food web. Knowing the electron requirement (Κ) for carbon (C) fixation (ΚC) and oxygen (O2) production (ΚO2), variable fluorescence has the potential to quantify primary production in microalgae, and hereby increasing spatial and temporal resolution of measurements compared to traditional methods. Here we quantify ΚC and ΚO2 through measures of Pulse Amplitude Modulated (PAM) fluorometry, C fixation and O2 production in an Arctic fjord (Godthåbsfjorden, W Greenland). Through short- (2h) and long-term (24h) experiments, rates of electron transfer (ETRPSII), C fixation and/or O2 production were quantified and compared. Absolute rates of ETR were derived by accounting for Photosystem II light absorption and spectral light composition. Two-hour incubations revealed a linear relationship between ETRPSII and gross 14C fixation (R2 = 0.81) during light-limited photosynthesis, giving a ΚC of 7.6 ± 0.6 (mean ± S.E.) mol é (mol C)−1. Diel net rates also demonstrated a linear relationship between ETRPSII and C fixation giving a ΚC of 11.2 ± 1.3 mol é (mol C)−1 (R2 = 0.86). For net O2 production the electron requirement was lower than for net C fixation giving 6.5 ± 0.9 mol é (mol O2)−1 (R2 = 0.94). This, however, still is an electron requirement 1.6 times higher than the theoretical minimum for O2 production [i.e. 4 mol é (mol O2)−1]. The discrepancy is explained by respiratory activity and non-photochemical electron requirements and the variability is discussed. In conclusion, the bio-optical method and derived electron requirement support conversion of ETR to units of C or O2, paving the road for improved spatial and temporal resolution of primary production estimates. PMID:26218096

  13. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

    ...     View Larger Image Stratus clouds are common in the Arctic during the summer months, and are ... formats available at JPL August 23, 2000 - Stratus clouds help modulate the arctic climate. project:  ...

  14. The vertical structure of Arctic haze as determined from airborne net-flux radiometer measurements

    NASA Technical Reports Server (NTRS)

    Ackerman, T. P.; Valero, F. P. J.

    1984-01-01

    From net-flux radiometer measurements and model results, the vertical layer structure is deduced of the Arctic haze encountered during two of the AGASP flights. The total value of the absorption optical depth is found to be on the order of 0.065 for both flights, with the majority of the absorbing aerosol concentrated in the lowest 1.6 km of the atmosphere. A comparison of these results with measurements of the carbon concentration leads to a value of the specific absorption of carbon of 24 sq m g. While higher than expected, this value is shown to be consistent with an internally-mixed aerosol of carbon cores and sulfate shells.

  15. A siliceous microfossil view of middle Eocene Arctic paleoenvironments: A window of biosilica production and preservation

    NASA Astrophysics Data System (ADS)

    Stickley, Catherine E.; Koç, NalâN.; Brumsack, Hans-Jürgen; Jordan, Richard W.; Suto, Itsuki

    2008-03-01

    Integrated Ocean Drilling Program (IODP) Expedition 302, "The Arctic Coring Expedition" (ACEX), unearthed the most significant find of Paleogene siliceous microfossils in nearly 2 decades. 100 m of early middle Eocene, organic-rich, finely laminated sediments contain abundant marine and freshwater siliceous microfossils allowing intriguing insights into central Arctic paleoenvironments during the start of Cenozoic cooling. Largely endemic assemblages of marine diatoms and ebridians are preserved along with very high abundances of chrysophyte cysts, the endogenously formed resting stage of freshwater algae. An overall brackish environment is invoked, but variations in group dominance suggest episodic changes in salinity, stratification, and trophic status. With the backing of inorganic geochemistry we synthesize the sediment characteristics by hypothesizing an environmental model for the cooccurrence of these diverse siliceous microfossil groups. We also report on initial insights into the composition of some of the laminations, which may help explain the formation of this rich sediment archive.

  16. Analysis of Oil and Gas Production in the Arctic National Wildlife Refuge

    EIA Publications

    2004-01-01

    This study analyzed the impact on future oil imports and expenditures of opening the Arctic National Wildlife Refuge (ANWR) to petroleum development. High, low, and mean ANWR oil resource case projections were compared to the Annual Energy Outlook 2004 reference case. The study also examined whether potential synergies exist in opening ANWR to petroleum development and the construction of an Alaska gas pipeline from the North Slope to the lower 48 states.

  17. Potential Oil Production from Coastal Plain of Arctic National Wildlife Refuge: Updated Assessment

    EIA Publications

    2000-01-01

    The Energy Information Administration (EIA) received a letter (dated March 10, 2000) from Senator Frank H. Murkowski as Chairman of the Senate Committee on Energy and Natural Resources requesting an EIA Service Report with plausible scenarios for the Arctic National Wildlife Refuge (ANWR) supply development consistent with the most recent U.S. Geological Survey resource assessments. This service report is prepared in response to the request of Senator Murkowski. It focuses on the ANWR coastal plain, a region currently restricted from exploration and development, and updates EIA's 1987 ANWR assessment.

  18. Estimation of primary production in the Arctic Ocean using ocean colour remote sensing and coupled physical-biological models: Strengths, limitations and how they compare

    NASA Astrophysics Data System (ADS)

    Babin, M.; Bélanger, S.; Ellingsen, I.; Forest, A.; Le Fouest, V.; Lacour, T.; Ardyna, M.; Slagstad, D.

    2015-12-01

    Over the last decade, several studies have reported a significant increase in marine primary production of the Arctic Ocean due mainly to a decrease in the extent of the icepack. Given the lack of in situ measurements, these studies were either based on prognostic models that use time series of remote sensing measurements of clouds, ice concentration and, most importantly, phytoplankton biomass at ocean surface (ocean colour remote sensing, OCRS), and coupled physical-biological ice-ocean (CPBO) dynamic models. In this paper, we review the strengths and limitations of these two approaches when applied in the Arctic Ocean. More specifically, we examine how they compare in terms of phytoplankton growth modelling and parameterisation, including relative to the current literature on measured Arctic phytoplankton growth parameters.

  19. Mid-summer mesozooplankton biomass, its size distribution, and estimated production within a glacial Arctic fjord (Hornsund, Svalbard)

    NASA Astrophysics Data System (ADS)

    Trudnowska, E.; Basedow, S. L.; Blachowiak-Samolyk, K.

    2014-09-01

    The estimation of secondary production constitutes an integrating proxy of pelagic ecosystem status, its functions as well as its responses to environmental stressors. The combination of high-resolution automatic measurements with a Laser Optical Plankton Counter (LOPC) and size spectrum analyses was utilized to estimate the secondary production of a high Arctic fjord during a summer post bloom situation in 2012. The dataset comprised 28 vertical and extensive horizontal hauls of a LOPC-CTD-fluorometer platform plus four zooplankton net sampling stations for taxonomic composition designation. A clear gradient in temperature, salinity, chlorophyll a concentrations as well as mesozooplankton abundance, biomass and production was demonstrated along Hornsund fjord axis. The outer fjord part was under the influence of water advection and had the highest chlorophyll a concentrations, numerous opaque mesozooplankton individuals and flat slopes of size spectra, pointing to long food chains in which biomass is recycled several times. The opposite state was found in the glacial bays, where the glacier meltwater discharge led to low chlorophyll a concentrations but high abundance of small and amorphous particles. It resulted in steep size spectra slopes and high intercepts implying higher potential productivity there. The model of mesozooplankton production demonstrated that Hornsund fjord is a highly productive ecosystem, particularly its upper water layer and its central parts. However, we would like to emphasize that a careful approach is needed before going deeper into ecological interpretations based on size spectra analysis, especially in reservoirs, where non-zooplankton particles contribute to the size spectra.

  20. Record-low primary productivity and high plant damage in the Nordic Arctic Region in 2012 caused by multiple weather events and pest outbreaks

    NASA Astrophysics Data System (ADS)

    Bjerke, Jarle W.; Rune Karlsen, Stein; Arild Høgda, Kjell; Malnes, Eirik; Jepsen, Jane U.; Lovibond, Sarah; Vikhamar-Schuler, Dagrun; Tømmervik, Hans

    2014-08-01

    The release of cold temperature constraints on photosynthesis has led to increased productivity (greening) in significant parts (32-39%) of the Arctic, but much of the Arctic shows stable (57-64%) or reduced productivity (browning, <4%). Summer drought and wildfires are the best-documented drivers causing browning of continental areas, but factors dampening the greening effect of more maritime regions have remained elusive. Here we show how multiple anomalous weather events severely affected the terrestrial productivity during one water year (October 2011-September 2012) in a maritime region north of the Arctic Circle, the Nordic Arctic Region, and contributed to the lowest mean vegetation greenness (normalized difference vegetation index) recorded this century. Procedures for field data sampling were designed during or shortly after the events in order to assess both the variability in effects and the maximum effects of the stressors. Outbreaks of insect and fungal pests also contributed to low greenness. Vegetation greenness in 2012 was 6.8% lower than the 2000-11 average and 58% lower in the worst affected areas that were under multiple stressors. These results indicate the importance of events (some being mostly neglected in climate change effect studies and monitoring) for primary productivity in a high-latitude maritime region, and highlight the importance of monitoring plant damage in the field and including frequencies of stress events in models of carbon economy and ecosystem change in the Arctic. Fourteen weather events and anomalies and 32 hypothesized impacts on plant productivity are summarized as an aid for directing future research.

  1. The Arctic Grand Challenge: Abrupt Climate Change

    NASA Astrophysics Data System (ADS)

    Wilkniss, P. E.

    2003-12-01

    Trouble in polar paradise (Science, 08/30/02), significant changes in the Arctic environment are scientifically documented (R.E. Moritz et al. ibid.). More trouble, lots more, "abrupt climate change," (R. B. Alley, et al. Science 03/28/03). R. Corell, Arctic Climate Impact Assessment team (ACIA), "If you want to see what will happen in the rest of the world 25 years from now just look what's happening in the Arctic," (Arctic Council meeting, Iceland, 08/03). What to do? Make abrupt Arctic climate change a grand challenge for the IPY-4 and beyond! Scientifically:Describe the "state" of the Arctic climate system as succinctly as possible and accept it as the point of departure.Develop a hypothesis and criteria what constitutes "abrupt climate change," in the Arctic that can be tested with observations. Observations: Bring to bear existing observations and coordinate new investments in observations through an IPY-4 scientific management committee. Make the new Barrow, Alaska, Global Climate Change Research Facility a major U.S. contribution and focal point for the IPY-4 in the U.S Arctic. Arctic populations, Native peoples: The people of the North are living already, daily, with wrenching change, encroaching on their habitats and cultures. For them "the earth is faster now," (I. Krupnik and D. Jolly, ARCUS, 2002). From a political, economic, social and entirely realistic perspective, an Arctic grand challenge without the total integration of the Native peoples in this effort cannot succeed. Therefore: Communications must be established, and the respective Native entities must be approached with the determination to create well founded, well functioning, enduring partnerships. In the U.S. Arctic, Barrow with its long history of involvement and active support of science and with the new global climate change research facility should be the focal point of choice Private industry: Resource extraction in the Arctic followed by oil and gas consumption, return the combustion

  2. Sea-ice distribution in the modern Arctic Ocean: Biomarker records from trans-Arctic Ocean surface sediments

    NASA Astrophysics Data System (ADS)

    Xiao, Xiaotong; Fahl, Kirsten; Müller, Juliane; Stein, Ruediger

    2015-04-01

    Records of the spatial and temporal variability of Arctic Ocean sea ice are of significance for understanding the causes of the dramatic decrease in Arctic sea-ice cover of recent years. In this context, the newly developed sea-ice proxy IP25, a mono-unsaturated highly branched isoprenoid alkene with 25 carbon atoms biosynthesized specifically by sea-ice associated diatoms and only found in Arctic and sub-Arctic marine sediments, has been used to reconstruct the recent spatial sea-ice distribution. The phytoplankton biomarkers 24S-brassicasterol and dinosterol were determined alongside IP25 to distinguish ice-free or permanent ice conditions, and to estimate the sea-ice conditions semi-quantitatively by means of the phytoplankton-IP25 index (PIP25). Within our study, for the first time a comprehensive data set of these biomarkers was produced using fresh and deep-frozen surface sediment samples from the Central Arctic Ocean proper (>80°N latitude) characterised by a permanent ice cover today and recently obtained surface sediment samples from the Chukchi Plateau/Basin partly covered by perennial sea ice. In addition, published and new data from other Arctic and sub-Arctic regions were added to generate overview distribution maps of IP25 and phytoplankton biomarkers across major parts of the modern Arctic Ocean. These comprehensive biomarker data indicate perennial sea-ice cover in the Central Arctic, ice-free conditions in the Barents Sea and variable sea-ice situations in other marginal seas. The low but more than zero values of biomarkers in the Central Arctic supported the low in-situ productivity there. The PIP25 index values reflect modern sea-ice conditions better than IP25 alone and show a positive correlation with spring/summer sea ice. When calculating and interpreting PIP25 index as a (semi-quantitative) proxy for reconstructions of present and past Arctic sea-ice conditions from different Arctic/sub-Arctic areas, information of the source of

  3. Contrasting activity patterns determined by BrdU incorporation in bacterial ribotypes from the Arctic Ocean in winter

    PubMed Central

    Galand, Pierre E.; Alonso-Sáez, Laura; Bertilsson, Stefan; Lovejoy, Connie; Casamayor, Emilio O.

    2013-01-01

    The winter Arctic Ocean is one of the most unexplored marine environments from a microbiological perspective. Heterotrophic bacteria maintain their activity at a baseline level during the extremely low-energy conditions of the winter, but little is known about the specific phylotypes that have the potential to survive and grow in such harsh environment. In this study, we aimed at identifying actively growing ribotypes in winter Arctic Ocean seawater cultures by experimental incubations with the thymidine analog bromodeoxyuridine (BrdU), followed by immunocapturing, terminal restriction fragment length polymorphism fingerprinting, cloning, and sequencing the 16S rRNA gene. We incubated water collected at different months over the Arctic winter and showed that the actively growing bacterial fraction, taking up BrdU, represented only a subset of the total community. Among the BrdU-labeled bacterial taxa we identified the Flavobacteria Polaribacter, the Alphaproteobacteria SAR11, the Gammaproteobacteria Arctic 96B-16 cluster and, predominately, members of Colwellia spp. Interestingly, Colwellia sequences formed three clusters (93 and 97% pairwise 16S rRNA identity) that contributed in contrasting ways to the active communities in the incubations. Polaribacter, Arctic 96B-16 and one cluster of Colwellia were more abundant in the active community represented by the BrdU-labeled DNA. In contrast, SAR11 and two other Colwellia clusters were underrepresented in the BrdU-labeled community compared to total communities. Despite the limitation of the long incubations needed to label slow growing arctic communities, the BrdU approach revealed the potential for active growth in low-energy conditions in some relevant groups of polar bacteria, including Polaribacter and Arctic 96B-16. Moreover, under similar incubation conditions, the growth of different Colwellia ribotypes varied, suggesting that related clusters of Colwellia may have distinct metabolic features. PMID:23750155

  4. Contrasting activity patterns determined by BrdU incorporation in bacterial ribotypes from the Arctic Ocean in winter.

    PubMed

    Galand, Pierre E; Alonso-Sáez, Laura; Bertilsson, Stefan; Lovejoy, Connie; Casamayor, Emilio O

    2013-01-01

    The winter Arctic Ocean is one of the most unexplored marine environments from a microbiological perspective. Heterotrophic bacteria maintain their activity at a baseline level during the extremely low-energy conditions of the winter, but little is known about the specific phylotypes that have the potential to survive and grow in such harsh environment. In this study, we aimed at identifying actively growing ribotypes in winter Arctic Ocean seawater cultures by experimental incubations with the thymidine analog bromodeoxyuridine (BrdU), followed by immunocapturing, terminal restriction fragment length polymorphism fingerprinting, cloning, and sequencing the 16S rRNA gene. We incubated water collected at different months over the Arctic winter and showed that the actively growing bacterial fraction, taking up BrdU, represented only a subset of the total community. Among the BrdU-labeled bacterial taxa we identified the Flavobacteria Polaribacter, the Alphaproteobacteria SAR11, the Gammaproteobacteria Arctic 96B-16 cluster and, predominately, members of Colwellia spp. Interestingly, Colwellia sequences formed three clusters (93 and 97% pairwise 16S rRNA identity) that contributed in contrasting ways to the active communities in the incubations. Polaribacter, Arctic 96B-16 and one cluster of Colwellia were more abundant in the active community represented by the BrdU-labeled DNA. In contrast, SAR11 and two other Colwellia clusters were underrepresented in the BrdU-labeled community compared to total communities. Despite the limitation of the long incubations needed to label slow growing arctic communities, the BrdU approach revealed the potential for active growth in low-energy conditions in some relevant groups of polar bacteria, including Polaribacter and Arctic 96B-16. Moreover, under similar incubation conditions, the growth of different Colwellia ribotypes varied, suggesting that related clusters of Colwellia may have distinct metabolic features. PMID:23750155

  5. Arctic Watch

    NASA Astrophysics Data System (ADS)

    Orcutt, John; Baggeroer, Arthur; Mikhalevsky, Peter; Munk, Walter; Sagen, Hanne; Vernon, Frank; Worcester, Peter

    2015-04-01

    The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This will be driven by increased demand for energy and the marine resources of an Arctic Ocean more accessible to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism and search and rescue will increase the pressure on the vulnerable Arctic environment. Synoptic in-situ year-round observational technologies are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual and decadal scales to inform and enable sustainable development and enforcement of international Arctic agreements and treaties, while protecting this critical environment. This paper will discuss multipurpose acoustic networks, including subsea cable components, in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic and anthropogenic), and acoustic remote sensing (tomography and thermometry), supporting and complementing data collection from platforms, moorings and autonomous vehicles. This paper supports the development and implementation of regional to basin-wide acoustic networks as an integral component of a multidisciplinary, in situ Arctic Ocean Observatory.

  6. Variability in primary productivity determines metapopulation dynamics.

    PubMed

    Fernández, Néstor; Román, Jacinto; Delibes, Miguel

    2016-04-13

    Temporal variability in primary productivity can change habitat quality for consumer species by affecting the energy levels available as food resources. However, it remains unclear how habitat-quality fluctuations may determine the dynamics of spatially structured populations, where the effects of habitat size, quality and isolation have been customarily assessed assuming static habitats. We present the first empirical evaluation on the effects of stochastic fluctuations in primary productivity-a major outcome of ecosystem functions-on the metapopulation dynamics of a primary consumer. A unique 13-year dataset from an herbivore rodent was used to test the hypothesis that inter-annual variations in primary productivity determine spatiotemporal habitat occupancy patterns and colonization and extinction processes. Inter-annual variability in productivity and in the growing season phenology significantly influenced habitat colonization patterns and occupancy dynamics. These effects lead to changes in connectivity to other potentially occupied habitat patches, which then feed back into occupancy dynamics. According to the results, the dynamics of primary productivity accounted for more than 50% of the variation in occupancy probability, depending on patch size and landscape configuration. Evidence connecting primary productivity dynamics and spatiotemporal population processes has broad implications for metapopulation persistence in fluctuating and changing environments. PMID:27053739

  7. Shifts in the hydrodynamic regime determine patterns of regional changes of the Arctic Ocean carbon cycle in future climate change projections

    NASA Astrophysics Data System (ADS)

    Ilyina, T.; Heinze, M.; Li, H.; Jungclaus, J. H.; Six, K. D.

    2015-12-01

    In future projections the Arctic Ocean carbon cycle is a hotspot for changes driven by rising CO2 emissions. Concomitantly, the Arctic Ocean hydrodynamic regime undergoes substantial shifts so the net effect on the carbon cycle is not intuitively clear. In the high CO2 scenario RCP8.5 extended until 2300 in projections of the Max Planck Institute's Earth System Model, the averaged Arctic Ocean surface temperature rises by 4°C in 2100 and by 10°C in 2300, respectively. The Arctic becomes free of summer sea ice in the second half of the 21st century, whereas winter sea ice disappears at the beginning of the 23rd century. Owing to increased sea ice melting and runoff, fresh water content increases gradually until the end of the 22nd century and then drops abruptly as a result of an intensification of the saline Atlantic water inflow. Accumulation of Atlantic water collapses the halocline in the central basin of the Arctic Ocean by the first half of the 23rd century. Ongoing warming enhances thermal stratification and the mixed layer shoales. In contrast, halocline erosion and the cooling of the ice free water act in concert to favor formation of convection cells in the central basin. Freshening in the Canada basin and transport of salty water into the Eurasian basin generate a dipole structure in the anomalies of surface salinity. Driven by the rising CO2, the averaged dissolved inorganic carbon (DIC) is growing. Changes in the averaged total alkalinity (TA) go along with the fresh water content evolution and decreasing carbonate ion concentration so that TA drops below preindustrial values. Yet, along with salinity, the Eurasian basin receives waters with higher DIC and TA from the Atlantic. As a result, the distributions of TA and DIC anomalies resemble the dipole pattern projected for salinity. We show that while future changes in the Arctic Ocean carbon cycle proceed at rates determined by atmospheric CO2 levels, the regional patterns are driven by shifts in the

  8. Date of Snowmelt at High Latitudes as Determined from Visible Satellite Data and Relationship with the Arctic Oscillation

    NASA Technical Reports Server (NTRS)

    Foster, James; Robinson, Dave; Estilow, Tom; Hall, Dorothy

    2012-01-01

    Spring snow cover across Arctic lands has, on average, retreated approximately five days earlier since the late 1980s compared to the previous twenty years. However, it appears that since about 1990, the date the snowline first retreats north during the spring has remained nearly unchanged--in the last twenty years, the date of snow disappearance has not been occurring noticeably earlier. Snowmelt changes observed in the 1980s was step-like in nature, unlike a more continuous downward trend seen in Arctic sea ice extent. At latitude 70 deg N, several latitudinal segments (of 10 degrees) show significant (negative) trends. However, only two latitudinal segments at 60 deg N show significant trends, one positive and one negative. These variations appear to be related to variations in the Arctic Oscillation (AO). Additional observations and modeling investigations are needed to better explain past and present spring melt characteristics and peculiarities.

  9. Mapping the future expansion of Arctic open water

    NASA Astrophysics Data System (ADS)

    Barnhart, Katherine R.; Miller, Christopher R.; Overeem, Irina; Kay, Jennifer E.

    2016-03-01

    Sea ice impacts most of the Arctic environment, from ocean circulation and marine ecosystems to animal migration and marine transportation. Sea ice has thinned and decreased in age over the observational record. Ice extent has decreased. Reduced ice cover has warmed the surface ocean, accelerated coastal erosion and impacted biological productivity. Declines in Arctic sea-ice extent cannot be explained by internal climate variability alone and can be attributed to anthropogenic effects. However, extent is a poor measure of ice decline at specific locations as it integrates over the entire Arctic basin and thus contains no spatial information. The open water season, in contrast, is a metric that represents the duration of open water over a year at an individual location. Here we present maps of the open water season over the period 1920-2100 using daily output from a 30-member initial-condition ensemble of business-as-usual climate simulations that characterize the expansion of Arctic open water, determine when the open water season will move away from pre-industrial conditions (`shift’ time) and identify when human forcing will take the Arctic sea-ice system outside its normal bounds (`emergence’ time). The majority of the Arctic nearshore regions began shifting in 1990 and will begin leaving the range of internal variability in 2040. Models suggest that ice will cover coastal regions for only half of the year by 2070.

  10. Sea-surface temperature and salinity product comparison against external in situ data in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Stroh, J. N.; Panteleev, Gleb; Kirillov, Sergey; Makhotin, Mikhail; Shakhova, Natalia

    2015-11-01

    Sea-surface temperature and salinity (SST/S) in the Arctic Ocean (AO) are largely governed by sea-ice and continental runoff rather than evaporation and precipitation as in lower latitude oceans, and global satellite analyses and models which incorporate remotely observed SST/S may be inaccurate in the AO due to lack of direct measurements for calibrating satellite data. For this reason, we are motivated to validate several satellite sea-surface temperature (SST) data products and SST/S models by comparing gridded data in the AO with oceanographic records from 2006 to 2013. Statistical analysis of product-minus-observation differences reveals that the satellite SST products considered have a temperature bias magnitude of less than 0.5°C compared to ship-based CTD measurements, and most of these biases are negative in sign. SST/S models also show an overall negative temperature bias, but no common sign or magnitude of salinity bias against CTD data. Ice tethered profiler (ITP) near-surface data span the seasons of several years, and these measurements reflect a sea-ice dominated region where the ocean surface cannot be remotely observed. Against this data, many of the considered models and products show large errors with detectable seasonal differences in SST bias. Possible sources of these errors are discussed, and two adjustments of product SST on the basis of sea-ice concentration are suggested for reducing bias to within less than 0.01°C of ITP near-surface temperatures.

  11. Variability in primary productivity determines metapopulation dynamics

    PubMed Central

    2016-01-01

    Temporal variability in primary productivity can change habitat quality for consumer species by affecting the energy levels available as food resources. However, it remains unclear how habitat-quality fluctuations may determine the dynamics of spatially structured populations, where the effects of habitat size, quality and isolation have been customarily assessed assuming static habitats. We present the first empirical evaluation on the effects of stochastic fluctuations in primary productivity—a major outcome of ecosystem functions—on the metapopulation dynamics of a primary consumer. A unique 13-year dataset from an herbivore rodent was used to test the hypothesis that inter-annual variations in primary productivity determine spatiotemporal habitat occupancy patterns and colonization and extinction processes. Inter-annual variability in productivity and in the growing season phenology significantly influenced habitat colonization patterns and occupancy dynamics. These effects lead to changes in connectivity to other potentially occupied habitat patches, which then feed back into occupancy dynamics. According to the results, the dynamics of primary productivity accounted for more than 50% of the variation in occupancy probability, depending on patch size and landscape configuration. Evidence connecting primary productivity dynamics and spatiotemporal population processes has broad implications for metapopulation persistence in fluctuating and changing environments. PMID:27053739

  12. Ice island creation, drift, recurrences, mechanical properties, and interactions with arctic offshore oil production structures

    SciTech Connect

    Sackinger, W.M.; Jeffries, M.O.; Li, Fucheng; Lu, Mingchi.

    1991-03-01

    Research and engineering studies on first-year sea ice for over two decades has resulted in the design, construction, and operation of jacket platforms, of artificial islands, and of massive gravity structures which routinely withstand moving sea ice of thickness up to 2 meters. However, the less-common interactions between such structures and moving multiyear ice ([ge]3 meters thick), and also moving ice islands (10 to 60 meters thick) remain as the unknown and potentially most serious hazard for Arctic offshore structures. In this study, research was addressed across the complete span of remaining questions regarding such features. Ice island components, thickness distributions, scenarios and models for the interactions of massive ice features with offshore structures, all were considered. Ice island morphology and calving studies were directed at the cluster of 19 ice islands produced in a calving from the Ward Hunt Ice Shelf on Ellesmere Island in 1983, and also at a calving from the Milne Ice Shelf in 1988. The statistics of ice island dynamics, on both a short-term small-scale basis and also on a long-term basis, were studied. Typical wind velocities of 5 to 7.5 meters per second led to ice island speeds of about 0.014 of the wind speed, at an angle of 20[degrees] to the right of the wind direction. Ice island samples were tested for their stress/strain characteristics. Compressive strength values ranged from 1.64 MPa at a strain rate of 2 [times] 10[sup [minus]7] s[sup [minus]1] to 6.75 MPa at a strain rate of 1 [times] 10[sup [minus]3] s[sup [minus]1]. Scenarios for ice island/structure interactions were developed, and protective countermeasures such as spray ice and ice rubble barriers were suggested. Additional computer modeling of structure/ice interactions for massive ice features is recommended.

  13. Estimating Determinants of Dentist Productivity: New Evidence

    PubMed Central

    Conrad, Douglas A.; Shuk-Yin Lee, Rosanna; Milgrom, Peter; Huebner, Colleen E.

    2013-01-01

    Objectives Productivity (output per unit of input) is a major driver of dental service capacity. This study uses 2006-2007 data to update available knowledge on dentist productivity. Methods In 2006-2007 the authors surveyed 1,604 Oregon general dentists regarding. hours worked, practice size, payment and patient mix, prices, dentist visits, and dentist characteristics. Effects of practice inputs and other independent variables on productivity were estimated by multiple regression and path analysis. Results The survey response rate was 55.2 percent. Dentists responding to the productivity-related questions were similar to dentists in the overall sampling frame and nationwide. Visits per week are significantly positively related to dentist hours worked, number of assistants, hygienists, and number of operatories. Dentist ownership status, years of experience, and % Medicaid patients are significantly positively related to practice output. The contributions of dentist chairside time and assistants to additional output are smaller for owners, but the number of additional dentist visits enabled by more hygienists is larger for owners. Conclusion As in earlier studies of dental productivity, the key determinant of dentist output is the dentist’s own chairside time. The incremental contributions of dentist time, auxiliaries, and operatories to production of dentist visits have not changed substantially over the past three decades. Future studies should focus on ultimate measures of output -- oral health -- and should develop more precise measures of the practice’s actual utilization of auxiliaries, their skill and use of technology. PMID:20545830

  14. Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season.

    PubMed

    Divoky, G J; Douglas, D C; Stenhouse, I J

    2016-09-01

    Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September-May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011-2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January-April. Most birds occupied the MIZ in regions averaging 30-60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d(-1), primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice. PMID:27601723

  15. CO2 and CH4 Production from Arctic Tundra Polygons: A Comparative Assessment of Temperature Sensitivity and Geochemical Controls

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, T.; Tang, G.; Herndon, E.; Elias, D. A.; Phelps, T. J.; Gu, B.; Liang, L.; Wullschleger, S. D.; Graham, D. E.

    2013-12-01

    Emissions of carbon dioxide (CO2) and methane (CH4) from Arctic and sub-Arctic tundra are highly variable and challenging to examine for geochemical and microbial controls. The large scale variability in in situ emission observations between high-centered and low-centered polygons and between microtopographic sites of a polygon (center, ridge and trough) underscores the difficulty of estimating precise regional to global-scale CO2 and CH4 emissions. This in turn poses a challenge to the extrapolation approaches used in predictive climate models for such complex high-latitude ecosystems. This study addresses the quantification and a comparative assessment of temperature sensitivity of CO2 and CH4 production rates between high-centered and low-centered polygons from the Barrow Environmental Observatory (Barrow, Alaska) under ecologically relevant experimental conditions. In addition, we elucidate the role of geochemical parameters including depth of organic matter, water content and pH in controlling the microbial pathways by which soil organic carbon are mineralized and CO2 and CH4 released. Intact frozen soil cores were collected from the center, ridge and trough areas of a low-centered polygon (LCP) and the center and trough of a high-centered polygon (HCP) using a SIPRE auger. A typical soil core consisted of a 0-20 cm deep organic (O) horizon, 20-50 cm deep mineral (B) horizon and 50-90 cm deep permafrost. The presence of significant amounts of iron(II) in O and B horizons constituting the active layer indicated predominantly anoxic soil biochemistry in the LCP and in the trough of the HCP. Therefore, soils were incubated in microcosms in anoxic or oxic conditions based on the redox conditions at three ecologically relevant temperatures of -2, +4 or +8 °C for up to 45 days. Production rates for both CH4 and CO2 were substantially higher in microcosms of O horizon at all temperatures, compared to B horizon samples at all sites of the LCP and the center of the

  16. 21st century projections of ocean ecology and productivity across the CMIP5 models: contrasting the Southern Ocean and the Arctic

    NASA Astrophysics Data System (ADS)

    Marinov, I.; Cabre, A.; Leung, S.

    2014-12-01

    We use the newest generation of fully-coupled earth system models to study and contrast the response of Southern Ocean and Arctic phytoplankton productivity and biomass to 21st century climate change. The Arctic is warming at a rate much higher than the Southern high latitudes. Despite fundamental differences between the physical responses to climate in these regions, CMIP5 modes predict small increases in biological production both in the SO and the Arctic, partially compensating for the severe loss of primary production in the rest of the oceans. South of 40ºS, the CMIP5 models predict a complex, zonally-banded pattern of phytoplankton abundance and productivity changes driven by shifts in light and iron availability with future warming, in agreement with patterns and mechanisms emerging from a satellite trend analysis and other recent observational work. Increased SAM plays a major role in these projections, as increased Southern Ocean westerlies act both to increase mixing and phytoplankton light limitation in a band around 50S, and to modify iron supply to the surface in regions where phytoplankton are iron limited. By contrast, phytoplankton are light and nitrate co-limited in the strongly stratified Arctic ocean. Here we find that over 100 years, release of light limitation due to sea ice retreat is counter-balanced by an increase in nitrogen limitation due to increased stratification. While most models predict net increases in Arctic production by the end of the 21st century, the different strengths of nutrient-light co-limitation among models result in different magnitude changes in production across models. We assess the multi-model 100-year trend significance using a novel technique based on bootstrap combined with a weighting scheme based in similarity across models. We find that model uncertainty in ecological and biogeochemical parameters is higher than for the physical parameters. Additionally, the spread in model predictions is smaller than the

  17. Arctic Browning: vegetation damage and implications for carbon balance.

    NASA Astrophysics Data System (ADS)

    Treharne, Rachael; Bjerke, Jarle; Emberson, Lisa; Tømmervik, Hans; Phoenix, Gareth

    2016-04-01

    'Arctic browning' is the loss of biomass and canopy in Arctic ecosystems. This process is often driven by climatic and biological extreme events - notably extreme winter warm periods, winter frost-drought and severe outbreaks of defoliating insects. Evidence suggests that browning is becoming increasingly frequent and severe at the pan-arctic scale, a view supported by observations from more intensely observed regions, with major and unprecedented vegetation damage reported at landscape (>1000km2) and regional (Nordic Arctic Region) scales in recent years. Critically, the damage caused by these extreme events is in direct opposition to 'Arctic greening', the well-established increase in productivity and shrub abundance observed at high latitudes in response to long-term warming. This opposition creates uncertainty as to future anticipated vegetation change in the Arctic, with implications for Arctic carbon balance. As high latitude ecosystems store around twice as much carbon as the atmosphere, and vegetation impacts are key to determining rates of loss or gain of ecosystem carbon stocks, Arctic browning has the potential to influence the role of these ecosystems in global climate. There is therefore a clear need for a quantitative understanding of the impacts of browning events on key ecosystem carbon fluxes. To address this, field sites were chosen in central and northern Norway and in Svalbard, in areas known to have been affected by either climatic extremes or insect outbreak and subsequent browning in the past four years. Sites were chosen along a latitudinal gradient to capture both conditions already causing vegetation browning throughout the Norwegian Arctic, and conditions currently common at lower latitudes which are likely to become more damaging further North as climate change progresses. At each site the response of Net Ecosystem CO2 Exchange to light was measured using a LiCor LI6400 Portable Photosynthesis system and a custom vegetation chamber with

  18. Characteristics of Arctic Ocean ice determined from SMMR data for 1979 - Case studies in the seasonal sea ice zone

    NASA Technical Reports Server (NTRS)

    Anderson, M. R.; Crane, R. G.; Barry, R. G.

    1985-01-01

    Sea ice data derived from the Scanning Multichannel Microwave Radiometer are examined for sections of the Arctic Ocean during early summer 1979. The temporary appearance of spuriously high multiyear ice fractions in the seasonal ice zones of the Kara and Barents Seas is a result of surface melt phenomena and the relative responses of the different channels to these effects. These spurious signatures can provide early identification of melt onset and additional information on surface characteristics.

  19. Recent Arctic Ocean sea ice loss triggers novel fall phytoplankton blooms

    NASA Astrophysics Data System (ADS)

    Ardyna, Mathieu; Babin, Marcel; Gosselin, Michel; Devred, Emmanuel; Rainville, Luc; Tremblay, Jean-Éric

    2014-09-01

    Recent receding of the ice pack allows more sunlight to penetrate into the Arctic Ocean, enhancing productivity of a single annual phytoplankton bloom. Increasing river runoff may, however, enhance the yet pronounced upper ocean stratification and prevent any significant wind-driven vertical mixing and upward supply of nutrients, counteracting the additional light available to phytoplankton. Vertical mixing of the upper ocean is the key process that will determine the fate of marine Arctic ecosystems. Here we reveal an unexpected consequence of the Arctic ice loss: regions are now developing a second bloom in the fall, which coincides with delayed freezeup and increased exposure of the sea surface to wind stress. This implies that wind-driven vertical mixing during fall is indeed significant, at least enough to promote further primary production. The Arctic Ocean seems to be experiencing a fundamental shift from a polar to a temperate mode, which is likely to alter the marine ecosystem.

  20. Critical review of mercury fates and contamination in the Arctic tundra ecosystem.

    PubMed

    Poissant, Laurier; Zhang, Hong H; Canário, João; Constant, Philippe

    2008-08-01

    Mercury (Hg) contamination in tundra region has raised substantial concerns, especially since the first report of atmospheric mercury depletion events (AMDEs) in the Polar Regions. During the past decade, steady progress has been made in the research of Hg cycling in the Polar Regions. This has generated a unique opportunity to survey the whole Arctic in respect to Hg issue and to find out new discoveries. However, there are still considerable knowledge gaps and debates on the fate of Hg in the Arctic and Antarctica, especially regarding the importance and significance of AMDEs vs. net Hg loadings and other processes that burden Hg in the Arctic. Some studies argued that climate warming since the last century has exerted profound effects on the limnology of High Arctic lakes, including substantial increases in autochthonous primary productivity which increased in sedimentary Hg, whereas some others pointed out the importance of the formation and postdeposition crystallographic history of the snow and ice crystals in determining the fate and concentration of mercury in the cryosphere in addition to AMDEs. Is mercury re-emitted back to the atmosphere after AMDEs? Is Hg methylation effective in the Arctic tundra? Where the sources of MeHg are? What is its fate? Is this stimulated by human made? This paper presents a critical review about the fate of Hg in the Arctic tundra, such as pathways and process of Hg delivery into the Arctic ecosystem; Hg concentrations in freshwater and marine ecosystems; Hg concentrations in terrestrial biota; trophic transfer of Hg and bioaccumulation of Hg through food chain. This critical review of mercury fates and contamination in the Arctic tundra ecosystem is assessing the impacts and potential risks of Hg contamination on the health of Arctic people and the global northern environment by highlighting and "perspectiving" the various mercury processes and concentrations found in the Arctic tundra. PMID:18707754

  1. Controls over nutrient flow through plants and microbes in Arctic tundra. Final report

    SciTech Connect

    Schimel, J.

    1994-02-01

    Ecosystem productivity in the Arctic is strongly controlled by N availability to plants. Thus, disturbances to the Arctic system are likely to have their greatest impacts by altering the supply of nutrients to plants. Thus, to understand the dynamics of Arctic tundra, a complete understanding of the controls on N cycling in tundra soils is necessary. This project focused on understanding nutrient dynamics in arctic tussock tundra, specifically evaluating the role of microbial uptake and competition for nutrients as a control on plant N-uptake. The project consisted of several major components: Short- and long-term partitioning of NH{sub 4}{sup +} in tussock tundra (1990--1991); Measurement of NH{sub 4}{sup +} uptake rates by Eriophorum vaginatum and by soil microbes; Determination of microbial NH{sub 4}{sup +} and NO{sub 3}{minus} uptake kinetics; and Determination of the partitioning of NH{sub 4}{sup +} and amino acids between E. vaginatum and soil microbes.

  2. 7 CFR 760.813 - Determination of production.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Determination of production. 760.813 Section 760.813... Determination of production. (a) Production under this part includes all harvested production, unharvested appraised production, and assigned production for the total planted acreage of the crop on the unit. (b)...

  3. BENTHIC PRODUCTION AS THE BASE FOR FOOD WEBS IN ALASKAN ARCTIC LAKES

    EPA Science Inventory

    Plankton are traditionally viewed as the basis for limnetic food webs, with zooplankton acting as an energy gateway between phytoplanktonic primary producers and fish. Often, benthic production is considered to be important primarily to the benthos and in shallow systems, such as...

  4. Microbial primary production on an Arctic glacier is insignificant in comparison with allochthonous organic carbon input.

    PubMed

    Stibal, Marek; Tranter, Martyn; Benning, Liane G; Rehák, Josef

    2008-08-01

    Cryoconite holes are unique freshwater environments on glacier surfaces, formed when solar-heated dark debris melts down into the ice. Active photoautotrophic microorganisms are abundant within the holes and fix inorganic carbon due to the availability of liquid water and solar radiation. Cryoconite holes are potentially important sources of organic carbon to the glacial ecosystem, but the relative magnitudes of autochthonous microbial primary production and wind-borne allochthonous organic matter brought are unknown. Here, we compare an estimate of annual microbial primary production in 2006 on Werenskioldbreen, a Svalbard glacier, with the organic carbon content of cryoconite debris. There is a great disparity between annual primary production (4.3 mug C g(-1) year(-1)) and the high content of organic carbon within the debris (1.7-4.5%, equivalent to 8500-22 000 mug C g(-1) debris). Long-term accumulation of autochthonous organic matter is considered unlikely due to ablation dynamics and the surface hydrology of the glacier. Rather, it is more likely that the majority of the organic matter on Werenskioldbreen is allochthonous. Hence, although glacier surfaces can be a significant source of organic carbon for glacial environments on Svalbard, they may be reservoirs rather than oases of high productivity. PMID:18430008

  5. Soil pH is a Key Determinant of Soil Fungal Community Composition in the Ny-Ålesund Region, Svalbard (High Arctic)

    PubMed Central

    Zhang, Tao; Wang, Neng-Fei; Liu, Hong-Yu; Zhang, Yu-Qin; Yu, Li-Yan

    2016-01-01

    This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic). A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS) region. The following eight soil properties were analyzed: pH, organic carbon (C), organic nitrogen (N), ammonium nitrogen (NH4+-N), silicate silicon (SiO42--Si), nitrite nitrogen (NO2--N), phosphate phosphorus (PO43--P), and nitrate nitrogen (NO3--N). A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs) were found. of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>eight soil samples) were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda) and analysis of similarities (ANOSIM) revealed that soil pH (p = 0.001) was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8–9, whereas Sordariales predominated in soils of pH 7–8 and Coniochaetales predominated in soils of pH 6–7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic. PMID:26955371

  6. Assessing determinants of maternal blood concentrations for persistent organic pollutants and metals in the eastern and western Canadian Arctic.

    PubMed

    Curren, Meredith S; Liang, Chun Lei; Davis, Karelyn; Kandola, Kami; Brewster, Janet; Potyrala, Mary; Chan, Hing Man

    2015-09-15

    Aboriginal peoples in the Canadian Arctic are exposed to persistent organic pollutants (POPs) and metals mainly through their consumption of a traditional diet of wildlife items. Recent studies indicate that many human chemical levels have decreased in the north, likely due to a combination of reduced global chemical emissions, dietary shifts, and risk mitigation efforts by local health authorities. Body burdens for chemicals in mothers can be further offset by breastfeeding, parity, and other maternal characteristics. We have assessed the impact of several dietary and maternal covariates following a decade of awareness of the contaminant issue in northern Canada, by performing multiple stepwise linear regression analyses from blood concentrations and demographic variables for 176 mothers recruited from Nunavut and the Northwest Territories during the period 2005-2007. A significant aboriginal group effect was observed for the modeled chemicals, except for lead and cadmium, after adjusting for covariates. Further, blood concentrations for POPs and metals were significantly associated with at least one covariate of older age, fewer months spent breastfeeding, more frequent eating of traditional foods, or smoking during pregnancy. Cadmium had the highest explained variance (72.5%) from just two significant covariates (current smoking status and parity). Although Inuit participants from the Northwest Territories consumed more traditional foods in general, Inuit participants from coastal communities in Nunavut continued to demonstrate higher adjusted blood concentrations for POPs and metals examined here. While this is due in part to a higher prevalence of marine mammals in the eastern Arctic diet, it is possible that other aboriginal group effects unrelated to diet may also contribute to elevated chemical body burdens in Canadian Arctic populations. PMID:25965033

  7. Earlier growing seasons and changes in migration timing influence carbon uptake and plant production in Arctic coastal wetlands

    NASA Astrophysics Data System (ADS)

    Leffler, A. J.; Beard, K. H.; Kelsey, K.; Choi, R. T.; Welker, J. M.

    2015-12-01

    The wetlands of the Yukon-Kuskokwim Delta in western Alaska are important breeding areas for geese and are experiencing rapid climate change, specifically earlier onset of the growing season. Consequently, geese arrive 'later' in the growing season than in the past, potentially setting up a phenological mismatch with consequences for their nutrition, plant growth, and C and N processes in the ecosystem. We examined the interactive effects between the start of the growing season and Black Brant arrival time on these processes in a manipulative experiment. Advancing the growing season had a modest influence on CO2 exchange and plant growth. An early growing season shifted the rate of net ecosystem exchange (NEE) by 1-1.5 µmol m-2 s-1 toward a carbon (C) source. This change was driven by an increase in the rate of ecosystem respiration (ER). The advanced growing season nearly doubled the rate of leaf elongation in the early summer and this difference persisted as taller vegetation later in the year; belowground biomass was not affected. Timing of grazing had greater influence on CO2 exchange and plant growth. Grazing early in the season shifted the system to a carbon source by ca. 2 μmol m-2 s-1 while delaying grazing enhanced the carbon sink by 1 μmol m-2 s-1. Here, the influence was not through ER, but through reducing and enhancing standing leaf area, respectively. Early grazing also reduced season-long root production by over 50% while delayed grazing enhanced root production by 30%. Although delaying grazing enhanced C uptake and promoted plant growth in this ecosystem, leaf tissue in delayed-grazing plots had C:N of 16.7 compared to 14.2 in the typical-grazing plots, potentially reducing the digestibility of goose forage and slowing rates of decomposition. Biotic forcing in arctic tundra can thus be major drivers of ecosystem function and need to be considered as tundra system respond to changing conditions.

  8. Arctic ice islands

    SciTech Connect

    Sackinger, W.M.; Jeffries, M.O.; Lu, M.C.; Li, F.C.

    1988-01-01

    The development of offshore oil and gas resources in the Arctic waters of Alaska requires offshore structures which successfully resist the lateral forces due to moving, drifting ice. Ice islands are floating, a tabular icebergs, up to 60 meters thick, of solid ice throughout their thickness. The ice islands are thus regarded as the strongest ice features in the Arctic; fixed offshore structures which can directly withstand the impact of ice islands are possible but in some locations may be so expensive as to make oilfield development uneconomic. The resolution of the ice island problem requires two research steps: (1) calculation of the probability of interaction between an ice island and an offshore structure in a given region; and (2) if the probability if sufficiently large, then the study of possible interactions between ice island and structure, to discover mitigative measures to deal with the moving ice island. The ice island research conducted during the 1983-1988 interval, which is summarized in this report, was concerned with the first step. Monte Carlo simulations of ice island generation and movement suggest that ice island lifetimes range from 0 to 70 years, and that 85% of the lifetimes are less then 35 years. The simulation shows a mean value of 18 ice islands present at any time in the Arctic Ocean, with a 90% probability of less than 30 ice islands. At this time, approximately 34 ice islands are known, from observations, to exist in the Arctic Ocean, not including the 10-meter thick class of ice islands. Return interval plots from the simulation show that coastal zones of the Beaufort and Chukchi Seas, already leased for oil development, have ice island recurrences of 10 to 100 years. This implies that the ice island hazard must be considered thoroughly, and appropriate safety measures adopted, when offshore oil production plans are formulated for the Alaskan Arctic offshore. 132 refs., 161 figs., 17 tabs.

  9. Preliminary Geospatial Analysis of Arctic Ocean Hydrocarbon Resources

    SciTech Connect

    Long, Philip E.; Wurstner, Signe K.; Sullivan, E. C.; Schaef, Herbert T.; Bradley, Donald J.

    2008-10-01

    Ice coverage of the Arctic Ocean is predicted to become thinner and to cover less area with time. The combination of more ice-free waters for exploration and navigation, along with increasing demand for hydrocarbons and improvements in technologies for the discovery and exploitation of new hydrocarbon resources have focused attention on the hydrocarbon potential of the Arctic Basin and its margins. The purpose of this document is to 1) summarize results of a review of published hydrocarbon resources in the Arctic, including both conventional oil and gas and methane hydrates and 2) develop a set of digital maps of the hydrocarbon potential of the Arctic Ocean. These maps can be combined with predictions of ice-free areas to enable estimates of the likely regions and sequence of hydrocarbon production development in the Arctic. In this report, conventional oil and gas resources are explicitly linked with potential gas hydrate resources. This has not been attempted previously and is particularly powerful as the likelihood of gas production from marine gas hydrates increases. Available or planned infrastructure, such as pipelines, combined with the geospatial distribution of hydrocarbons is a very strong determinant of the temporal-spatial development of Arctic hydrocarbon resources. Significant unknowns decrease the certainty of predictions for development of hydrocarbon resources. These include: 1) Areas in the Russian Arctic that are poorly mapped, 2) Disputed ownership: primarily the Lomonosov Ridge, 3) Lack of detailed information on gas hydrate distribution, and 4) Technical risk associated with the ability to extract methane gas from gas hydrates. Logistics may control areas of exploration more than hydrocarbon potential. Accessibility, established ownership, and leasing of exploration blocks may trump quality of source rock, reservoir, and size of target. With this in mind, the main areas that are likely to be explored first are the Bering Strait and Chukchi

  10. An assessment of phytoplankton primary productivity in the Arctic Ocean from satellite ocean color/in situ chlorophyll-a based models

    NASA Astrophysics Data System (ADS)

    Lee, Younjoo J.; Matrai, Patricia A.; Friedrichs, Marjorie A. M.; Saba, Vincent S.; Antoine, David; Ardyna, Mathieu; Asanuma, Ichio; Babin, Marcel; Bélanger, Simon; Benoît-Gagné, Maxime; Devred, Emmanuel; Fernández-Méndez, Mar; Gentili, Bernard; Hirawake, Toru; Kang, Sung-Ho; Kameda, Takahiko; Katlein, Christian; Lee, Sang H.; Lee, Zhongping; Mélin, Frédéric; Scardi, Michele; Smyth, Tim J.; Tang, Shilin; Turpie, Kevin R.; Waters, Kirk J.; Westberry, Toby K.

    2015-09-01

    We investigated 32 net primary productivity (NPP) models by assessing skills to reproduce integrated NPP in the Arctic Ocean. The models were provided with two sources each of surface chlorophyll-a concentration (chlorophyll), photosynthetically available radiation (PAR), sea surface temperature (SST), and mixed-layer depth (MLD). The models were most sensitive to uncertainties in surface chlorophyll, generally performing better with in situ chlorophyll than with satellite-derived values. They were much less sensitive to uncertainties in PAR, SST, and MLD, possibly due to relatively narrow ranges of input data and/or relatively little difference between input data sources. Regardless of type or complexity, most of the models were not able to fully reproduce the variability of in situ NPP, whereas some of them exhibited almost no bias (i.e., reproduced the mean of in situ NPP). The models performed relatively well in low-productivity seasons as well as in sea ice-covered/deep-water regions. Depth-resolved models correlated more with in situ NPP than other model types, but had a greater tendency to overestimate mean NPP whereas absorption-based models exhibited the lowest bias associated with weaker correlation. The models performed better when a subsurface chlorophyll-a maximum (SCM) was absent. As a group, the models overestimated mean NPP, however this was partly offset by some models underestimating NPP when a SCM was present. Our study suggests that NPP models need to be carefully tuned for the Arctic Ocean because most of the models performing relatively well were those that used Arctic-relevant parameters.

  11. Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that tends to increase its sensitivity to climate change. Its temperature, salinity, and ice cover have all undergone changes in the past several decades, although it is uncertain whether these predominantly reflect long-term trends, oscillations within the system, or natural variability. Major changes include a warming and expansion of the Atlantic layer, at depths of 200-900 m, a warming of the upper ocean in the Beaufort Sea, a considerable thinning (perhaps as high as 40%) of the sea ice cover, a lesser and uneven retreat of the ice cover (averaging approximately 3% per decade), and a mixed pattern of salinity increases and decreases.

  12. Arctic and offshore research: Technology status report

    SciTech Connect

    Not Available

    1988-01-01

    This report describes the state of technology relative to the production of oil and gas in the Arctic. It discusses the technical issues that warrant investigation, and focuses on the current Department of Energy supported activities. Major accomplishments during the last year include the following: The Arctic and Offshore Research Information System (AORIS) was planned with industry survey recommendations incorporated. It contains a directory of 85 Arctic databases, a bibliographic component of over 7,000 citations, and a data component of about 300 data sets on sea ice characteristics. Seven position, pressure, and temperature buoys were deployed on ice islands (up to 3 by 6 miles in size) drifting off Ellesmere Island. Ice island movement, as much as 340 miles southwest of the Ward Hunt Ice Shelf during the last 4 years, represents a potential hazard to Arctic offshore structures in the Alaskan Beaufort Sea. The redesigned Seafloor Earthquake Measurement System (SEMS II) was deployed near Shell's Ellen-Elly platforms, about 10 miles offshore of Long Beach, California. The SEMS monitored the July 1986 southern California earthquakes. This was the first time earthquakes were simultaneouslly monitored by sensors located on land, aboard offshore platforms, and beneath the seafloor. Sea spray ice bond shear strength to various structural and protective coatings has been determined. The polyethylene coating demonstrated the most potential for rapid shedding of spray ice by gravity loading. Measurements of temperatures and salinities were completed as part of a pilot test to (1) detect seasonal conditions at the water-seabed interface, and (2) determine how they influence permafrost growth in the coastal waters of the Beaufort Sea. The temperatures and computed freezing point data suggest that seasonal seabed freezing can occur most of the winter. 13 refs., 14 figs., 4 tabs.

  13. 7 CFR 760.637 - Determination of production.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Determination of production. 760.637 Section 760.637....637 Determination of production. (a) Except for value loss crops, production for the purposes of this part includes all harvested, appraised, and assigned production for the payment acres...

  14. 7 CFR 760.637 - Determination of production.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Determination of production. 760.637 Section 760.637....637 Determination of production. (a) Except for value loss crops, production for the purposes of this part includes all harvested, appraised, and assigned production for the payment acres...

  15. 7 CFR 760.637 - Determination of production.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Determination of production. 760.637 Section 760.637....637 Determination of production. (a) Except for value loss crops, production for the purposes of this part includes all harvested, appraised, and assigned production for the payment acres...

  16. 7 CFR 760.637 - Determination of production.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Determination of production. 760.637 Section 760.637....637 Determination of production. (a) Except for value loss crops, production for the purposes of this part includes all harvested, appraised, and assigned production for the payment acres...

  17. 7 CFR 760.637 - Determination of production.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Determination of production. 760.637 Section 760.637....637 Determination of production. (a) Except for value loss crops, production for the purposes of this part includes all harvested, appraised, and assigned production for the payment acres...

  18. Effects of fish density and river fertilization on algal standing stocks, invertebrates communities, and fish production in an Arctic River

    USGS Publications Warehouse

    Deegan, Linda A.; Peterson, B.J.; Golden, H.; McIvor, C.C.; Miller, M.C.

    1997-01-01

    This study examined the relative importance of bottom-up and top-down controls of an arctic stream food web by simultaneous manipulation of the top predator and nutrient availability. We created a two-step trophic system (algae to insects) by removal of the top predator (Arctic grayling, Thymallus arcticus) in fertilized and control stream reaches. Fish abundance was also increased 10 times to examine the effect of high fish density on stream ecosystem dynamics and fish. We measured the response of epilithic algae, benthic and drifting insects, and fish to nutrient enrichment and to changes in fish density. Insect grazers had little effect on algae and fish had little effect on insects. In both the control and fertilized reaches, fish growth, energy storage, and reproductive response of females declined with increased fish density. Fish growth and energy storage were more closely correlated with per capita insect availability than with per capita algal standing stock

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

    NASA Astrophysics Data System (ADS)

    Bergeron, Myriam; Tremblay, Jean-Éric

    2014-06-01

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

  20. Effect of warming on the degradation and production of low-molecular-weight labile organic carbon in an Arctic tundra soil

    DOE PAGESBeta

    Yang, Ziming; Wullschleger, Stan D.; Liang, Liyuan; Graham, David E.; Gu, Baohua

    2016-01-16

    The fate of soil organic carbon (SOC) stored in the Arctic permafrost is a key concern as temperatures continue to rise in the northern hemisphere. Studies and conceptual models suggest that SOC degradation is affected by the composition of SOC, but it is unclear exactly what portions of SOC are vulnerable to rapid breakdown and what mechanisms may be controlling SOC degradation upon permafrost thaw. Here, we examine the dynamic consumption and production of labile SOC in an anoxic incubation experiment using soil samples from the active layer at the Barrow Environmental Observatory, Barrow, Alaska, USA. Free-reducing sugars, alcohols, andmore » low-molecular-weight (LMW) organic acids were analyzed during incubation at either –2 or 8 °C for up to 240 days. Results show that simple sugar and alcohol SOC largely account for the initial rapid release of CO2 and CH4 through anaerobic fermentation, whereas the fermentation products, acetate and formate, are subsequently utilized as primary substrates for methanogenesis. Iron(III) reduction is correlated to acetate production and methanogenesis, suggesting its important role as an electron acceptor in tundra SOC respiration. These observations are further supported in a glucose addition experiment, in which rapid CO2 and CH4 production occurred concurrently with rapid production and consumption of labile organics such as acetate. However, addition of tannic acid, as a more complex organic substrate, showed little influence on the overall production of CO2 and CH4 and organic acids. Together our study shows that LMW labile organics in SOC control the initial rapid release of green-house gases upon warming. We thus present a conceptual framework for the labile SOC transformations and their relations to fermentation, iron reduction and methanogenesis, thereby providing the basis for improved model prediction of climate feedbacks in the Arctic.« less

  1. Communicating Climate and Ecosystem Change in the Arctic

    NASA Astrophysics Data System (ADS)

    Soreide, N. N.; Overland, J. E.; Calder, J. A.; Rodionov, S.

    2005-12-01

    There is an explosion of interest in Northern Hemisphere climate, highlighting the importance of recent changes in the Arctic on mid-latitude climate and its impact on marine and terrestrial ecosystems. Traditional sea ice and tundra dominated arctic ecosystems are being reorganizing into warmer sub-arctic ecosystem types. Over the previous two years we have developed a comprehensive, near real-time arctic change detection protocol to track physical and biological changes for presentation on the web: http://www.arctic.noaa.gov/detect. The effort provides a continuous update to the Arctic Climate Impact Assessment (ACIA) Report, released in November 2004. Principles for the protocol include an accessible narrative style, scientifically credible and objective indicators, notes multiple uses for the information, acknowledges uncertainties, and balances having too many indicators-which leads to information overload-and too few-which does not capture the complexity of the system. Screening criteria include concreteness, public awareness, being understandable, availability of historical time series, and sensitivity. The site provides sufficient information for an individual to make their own assessment regarding the balance of the evidence for tracking change. The product provides an overview, recent news, links to many arctic websites, and highlights climate, global impacts, land and marine ecosystems, and human consequences. Since its inception a year ago, it has averaged about 9000 hits an day on the web, and is a major information source as determined by Google search. The future direction focuses on understanding the causes for change. In spring 2005 we also presented a near real-time ecological and climatic surveillance website for the Bering Sea: www.beringclimate.noaa.gov. The site provides up-to-date information which ties northward shifts of fish, invertebrate and marine mammal populations to physical changes in the Arctic. This site is more technical than the

  2. Identification of 'Candidatus Piscichlamydia salmonis' in Arctic charr Salvelinus alpinus during a survey of charr production facilities in North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Artic charr Salvelinus alpinus production facilities, nonproduction water sources and effluents in the United States and Canada were sampled to determine if chlamydiae associated with epitheliocystis were present in water and were associated with inclusions of epitheliocystis in gill tissue. Gills f...

  3. Arctic Social Sciences: Opportunities in Arctic Research.

    ERIC Educational Resources Information Center

    Arctic Research Consortium of the United States, Fairbanks, AK.

    The U.S. Congress passed the Arctic Research and Policy Act in 1984 and designated the National Science Foundation (NSF) the lead agency in implementing arctic research policy. In 1989, the parameters of arctic social science research were outlined, emphasizing three themes: human-environment interactions, community viability, and rapid social…

  4. Evaluation of arctic multibeam sonar data quality using nadir crossover error analysis and compilation of a full-resolution data product

    NASA Astrophysics Data System (ADS)

    Flinders, Ashton F.; Mayer, Larry A.; Calder, Brian A.; Armstrong, Andrew A.

    2014-05-01

    We document a new high-resolution multibeam bathymetry compilation for the Canada Basin and Chukchi Borderland in the Arctic Ocean - United States Arctic Multibeam Compilation (USAMBC Version 1.0). The compilation preserves the highest native resolution of the bathymetric data, allowing for more detailed interpretation of seafloor morphology than has been previously possible. The compilation was created from multibeam bathymetry data available through openly accessible government and academic repositories. Much of the new data was collected during dedicated mapping cruises in support of the United States effort to map extended continental shelf regions beyond the 200 nm Exclusive Economic Zone. Data quality was evaluated using nadir-beam crossover-error statistics, making it possible to assess the precision of multibeam depth soundings collected from a wide range of vessels and sonar systems. Data were compiled into a single high-resolution grid through a vertical stacking method, preserving the highest quality data source in any specific grid cell. The crossover-error analysis and method of data compilation can be applied to other multi-source multibeam data sets, and is particularly useful for government agencies targeting extended continental shelf regions but with limited hydrographic capabilities. Both the gridded compilation and an easily distributed geospatial PDF map are freely available through the University of New Hampshire's Center for Coastal and Ocean Mapping (ccom.unh.edu/theme/law-sea). The geospatial pdf is a full resolution, small file-size product that supports interpretation of Arctic seafloor morphology without the need for specialized gridding/visualization software.

  5. Arctic Collaborative Environment: A New Multi-National Partnership for Arctic Science and Decision Support

    NASA Technical Reports Server (NTRS)

    Laymon, Charles A,; Kress, Martin P.; McCracken, Jeff E.; Spehn, Stephen L.; Tanner, Steve

    2011-01-01

    The Arctic Collaborative Environment (ACE) project is a new international partnership for information sharing to meet the challenges of addressing Arctic. The goal of ACE is to create an open source, web-based, multi-national monitoring, analysis, and visualization decision-support system for Arctic environmental assessment, management, and sustainability. This paper will describe the concept, system architecture, and data products that are being developed and disseminated among partners and independent users through remote access.

  6. Arctic Languages: An Awakening.

    ERIC Educational Resources Information Center

    Collis, Dermid R. F., Ed.

    This work is a study of Arctic languages written in an interdisciplinary manner. Part of the Unesco Arctic project aimed at safeguarding the linguistic heritage of Arctic peoples, the book is the outcome of three Unesco meetings at which conceptual approaches to and practical plans for the study of Arctic cultures and languages were worked out.…

  7. Nutrient Limitation of Microbial Mediated Decomposition and Arctic Soil Chronology

    NASA Astrophysics Data System (ADS)

    Melle, C. J.; Darrouzet-Nardi, A.; Wallenstein, M. D.

    2012-12-01

    effective soil age. My research is focused on addressing the questions of the extent of microbial N limitation in arctic tundra soils, the potential for co-limitation of labile C despite a high SOC environment, and the dependence, if any, nutrient limitation may have on the effective age of the soil. I have addressed these questions by conducting a laboratory soil incubation of factorial design with treatments of amended glucose, amended ammonium nitrate, and a control consisting of an addition of an equivalent volume of deionized water. Moist acid tundra soils possessing similar soil properties from two arctic sites of close proximity yet with varying deglaciation chronologies were utilized in my study. Soil properties of C-mineralization via respiration, microbial biomass, and nitrogen content in the forms of ammonium, nitrate, and total free amino acids and microbial extra-cellular enzyme production were assayed to determine the microbial response to the experimental treatments. Through the results of this work, I hope to better our understanding of biogeochemical cycling within arctic tundra ecosystems and the response to climate change by contributing to existing knowledge of nutrient limitation on microbial mediated decomposition of SOC in the arctic and how this may differ in soils of varying effective age.

  8. Record Arctic ozone depletion could occur again

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-02-01

    In the winter of 2010-2011, ozone levels above the Arctic declined to record lows, creating the first Arctic ozone hole, similar to the well-known Antarctic ozone hole. Scientists believe the ozone depletion was due partly to unusually cold temperatures in the stratosphere above the Arctic, as colder stratospheric temperatures make ozone-destroying chemicals such as chlorine more active. As global climate change continues, the Arctic stratosphere is expected to get colder, but levels of ozone-destroying chemicals should decline, as emissions of these chemicals were banned by the Montreal Protocol. To try to learn more about Arctic ozone dynamics and determine whether the Arctic ozone hole is likely to recur, Sinnhuber et al. looked at satellite observations of temperature, ozone, water vapor, and chemicals that affect ozone in the Arctic atmosphere. They also used a model to determine how sensitive ozone levels are to stratospheric temperatures and chemistry. They found that their model accurately reproduced measured conditions. Their model suggests that stratospheric temperatures 1°C lower than in the 2010-2011 winter would result in locally nearly complete ozone depletion in the Arctic lower stratosphere with current levels of chemicals. A 10% reduction in ozone-depleting chemicals would be offset by a 1°C decrease in stratospheric temperatures.

  9. The merits of using Primary Peak Retrackers for determination of Sea Surface Heights/Gravity Fields in the Arctic using Cryosat-2 SAR Altimetry

    NASA Astrophysics Data System (ADS)

    Jain, Maulik; Baltazar Andersen, Ole; Dall, Jorgen; Stenseng, Lars

    2014-05-01

    Precise sea surface height estimation and gravity field estimation is done using Cryosat-2 SAR (Synthetic Aperture Radar) data. First, using Cryosat-2 altimetric data, precise sea surface heights are computed. Gravity field is next determined based on the along track variation of the sea surface height anomaly. Thus precise sea surface height determination using Cryosat-2 SAR data is critical for reliable gravity field determination. This work involves improvement and customization of classical empirical retrackers for sea surface height determination. Classical retrackers work well in open ocean, but in cryospheric areas, like in the Arctic which have a significant presence of sea ice, the classical retrackers either fail or provide unreliable sea surface heights. The Arctic has this typical problem where the SAR echo waveforms are contaminated because of superposition of echoes from sea ice and water and hence a need of customization/improvement in classical empirical retrackers is desired. In order to make this improvement, the primary peak of the SAR waveform is extracted and isolated from the rest of the waveform. Next, the classical OCOG ( Offset Centre of Gravity) and Threshold retrackers are applied on this extracted primary peak rather than the complete waveform. The extraction of the primary peak is helpful as this is the part of the reflected waveform where interaction between the altimetric pulses and the sea surface occurs. The extraction of the primary peak is based on start/stop thresholds based on the standard deviation of power difference in consecutive/alternate bins of the complete reflected waveform. After processing is done based on the Primary Peak retrackers, the sea surface heights are computed and gravity fields are determined from the same. There are two methods of evaluating the performance of the retrackers. In the first method, the sea surface heights are corrected, the mean sea surface is removed and various geophysical corrections are

  10. Arctic & Offshore Technical Data System

    Energy Science and Technology Software Center (ESTSC)

    1990-07-01

    AORIS is a computerized information system to assist the technology and planning community in the development of Arctic oil and gas resources. In general, AORIS is geographically dependent and, where possible, site specific. The main topics are sea ice, geotechnology, oceanography, meteorology, and Arctic engineering, as they relate to such offshore oil and gas activities as exploration, production, storage, and transportation. AORIS consists of a directory component that identifies 85 Arctic energy-related databases and tellsmore » how to access them; a bibliographic/management information system or bibliographic component containing over 8,000 references and abstracts on Arctic energy-related research; and a scientific and engineering information system, or data component, containing over 800 data sets, in both tabular and graphical formats, on sea ice characteristics taken from the bibliographic citations. AORIS also contains much of the so-called grey literature, i.e., data and/or locations of Arctic data collected, but never published. The three components are linked so the user may easily move from one component to another. A generic information system is provided to allow users to create their own information systems. The generic programs have the same query and updating features as AORIS, except that there is no directory component.« less

  11. Elemental composition of arctic particulate matter

    NASA Technical Reports Server (NTRS)

    Cahill, T. A.; Eldred, R. A.

    1984-01-01

    Measurements were made of the elemental composition of particulate matter collected in flights in the Arctic in spring 1983 as part of the Arctic Gas and Aerosol Sampling Program (AGASP). Ten samples of size-selected particles were analyzed by four nondestructive techniques at Davis. Concentrations were determined for H, C, N, and O by Forward Alpha Scattering Techniques (FAST) and for elements heavier than fluorine by Particle Induced X-ray Emission (PIXE). Total mass was measured gravimetrically, and optical absorption was measured using the Laser Integrating Plate Method (LIPM). Results of the analyses show dramatic differences in concentrations and elemental ratios from the Alaskan Arctic to the Norwegian Arctic, with indications of wood smoke and sulfuric acid in the arctic atmosphere.

  12. Satellite Remote Sensing of Pan-arctic Vegetation Productivity, Soil Respiration and net CO2 Exchange Using MODIS and AMSR-E Data

    NASA Astrophysics Data System (ADS)

    Nirala, M. L.; Heinsch, F. A.; Kimball, J. S.; Zhao, M.; Running, S.; Oechel, W.; McDonald, K.; Njoku, E.

    2005-05-01

    We have developed an approach for regional assessment and monitoring of land-atmosphere carbon dioxide (CO2) exchange, soil heterotrophic respiration (Rh) and vegetation productivity for arctic tundra using global satellite remote sensing at optical and microwave wavelengths. We use C- and X-band brightness temperatures from AMSR-E to extract surface wetness and temperature, and MODIS data to derive land cover, Leaf Area Index (LAI) and Net Primary Production (NPP) information. Calibration and validation activities involve comparisons between satellite remote sensing and tundra CO2 eddy flux tower and biophysical measurement networks and hydro-ecological process model simulations. We analyze spatial and temporal anomalies and environmental drivers of land-atmosphere net CO2 exchange at weekly and annual time steps. Surface soil moisture status and temperature as detected from satellite remote sensing observations are found to be major drivers spatial and temporal patterns of tundra net CO2 exchange and photosynthetic and respiration processes. We also find that satellite microwave measurements are capable of capturing seasonal variations and regional patterns in tundra soil heterotrophic respiration and CO2 exchange, while our ability to extract spatial patterns at the scale of surface heterogeneity is limited by the coarse spatial scale of the satellite remote sensing footprint. Our results also indicate that carbon cycle response to climate change is non-linear and strongly coupled to arctic surface hydrology. This work was performed at The University of Montana and Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  13. Pan-Arctic distributions of continental runoff in the Arctic Ocean

    PubMed Central

    Fichot, Cédric G.; Kaiser, Karl; Hooker, Stanford B.; Amon, Rainer M. W.; Babin, Marcel; Bélanger, Simon; Walker, Sally A.; Benner, Ronald

    2013-01-01

    Continental runoff is a major source of freshwater, nutrients and terrigenous material to the Arctic Ocean. As such, it influences water column stratification, light attenuation, surface heating, gas exchange, biological productivity and carbon sequestration. Increasing river discharge and thawing permafrost suggest that the impacts of continental runoff on these processes are changing. Here, a new optical proxy was developed and implemented with remote sensing to determine the first pan-Arctic distribution of terrigenous dissolved organic matter (tDOM) and continental runoff in the surface Arctic Ocean. Retrospective analyses revealed connections between the routing of North American runoff and the recent freshening of the Canada Basin, and indicated a correspondence between climate-driven changes in river discharge and tDOM inventories in the Kara Sea. By facilitating the real-time, synoptic monitoring of tDOM and freshwater runoff in surface polar waters, this novel approach will help understand the manifestations of climate change in this remote region. PMID:23316278

  14. Production of dissolved organic carbon by Arctic plankton communities: Responses to elevated carbon dioxide and the availability of light and nutrients

    NASA Astrophysics Data System (ADS)

    Poulton, Alex J.; Daniels, Chris J.; Esposito, Mario; Humphreys, Matthew P.; Mitchell, Elaine; Ribas-Ribas, Mariana; Russell, Benjamin C.; Stinchcombe, Mark C.; Tynan, Eithne; Richier, Sophie

    2016-05-01

    The extracellular release of dissolved organic carbon (DOC) by phytoplankton is a potentially important source of labile organic carbon for bacterioplankton in pelagic ecosystems. In the context of increasing seawater partial pressure of CO2 (pCO2), via the oceanic absorption of elevated atmospheric CO2 (ocean acidification), several previous studies have reported increases to the relative amount of carbon fixed into particulates, via primary production (PP), and dissolved phases (DOC). During the summer of 2012 we measured DOC production by phytoplankton communities in the Nordic seas of the Arctic Ocean (Greenland, Norwegian and Barents Sea) from both in situ sampling and during three bioassay experiments where pCO2 levels (targets ~550 μatm, ~750 μatm, ~1000 μatm) were elevated relative to ambient conditions. Measurements of DOC production and PP came from 24 h incubations and therefore represent net DOC production rates, where an unknown portion of the DOC released has potentially been utilised by heterotrophic organisms. Production of DOC (net pDOC) by in situ communities varied from 0.09 to 0.64 mmol C m-3 d-1 (average 0.25 mmol C m-3 d-1), with comparative rates in two of the experimental bioassays (0.04-1.23 mmol C m-3 d-1) and increasing dramatically in the third (up to 5.88 mmol C m-3 d-1). When expressed as a fraction of total carbon fixation (i.e., PP plus pDOC), percentage extracellular release (PER) was 14% on average (range 2-46%) for in situ measurements, with PER in the three bioassays having a very similar range (2-50%). A marked increase in pDOC (and PER) was only observed in one of the bioassays where nutrient levels (nitrate, silicic acid) dropped dramatically relative to starting (ambient) concentrations; no pCO2 treatment effect on pDOC (or PER) was evident across the three experiments. Examination of in situ net pDOC (and PER) found significant correlations with decreasing silicic acid and increasing euphotic zone depth, indicating that

  15. Zooplankton in the Arctic outflow

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    Stern, G A; Braekevelt, E; Helm, P A; Bidleman, T F; Outridge, P M; Lockhart, W L; McNeeley, R; Rosenberg, B; Ikonomou, M G; Hamilton, P; Tomy, G T; Wilkinson, P

    2005-04-15

    Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production. The lower than expected HOC concentrations in older sediment slices may be due to anaerobic degradation and possibly to dilution resulting from a temporary increase in sedimentation rate observed between the mid-1960s and 1970s. Indeed, temporal trends were more readily apparent for those compound classes when anaerobic metabolites were also analyzed, such as for DDT and toxaphene. However, it is postulated here for the first time that the maximum or increasing HOC surface fluxes observed for many of the major compound classes in DV09 sediments may be influenced by climate variation and the resulting increase in algal primary productivity which could drive an increasing rate of HOC scavenging from the water column. Both the fraction (F(TC)) and enantiomer fraction (EF) of trans-chlordane (TC) decreased significantly between 1957 and 1997, suggesting that recent inputs to the lake are from weathered chlordane sources. PCDD/Fs showed a change in sources from pentachlorophenol (PeCP) in the 1950s and 1960s to combustion sources into the 1990s. Improvements in combustion technology may be responsible for the reducing the proportion of TCDF relative to OCDD in the most recent slice. PMID:15866277

  17. Arctic in Rapid Transition (art): Integrating Priorities for Arctic Marine Science Over the Next Decade

    NASA Astrophysics Data System (ADS)

    Wegner, C.; Forest, A.; Forwick, M.; Frey, K. E.; Mathis, J. T.; Michel, C.; Nikolopoulos, A.; O'Regan, M. A.; Peeken, I.; Reigstad, M.

    2010-12-01

    within the ART Initiative will be to bridge gaps in knowledge not only across disciplinary boundaries (e.g., biology, geochemistry, geology, meteorology, physical oceanography), but also across geographic (e.g., intenational boundaries, shelves, margins, and the central Arctic Ocean) and temporal boundaries (e.g., paleo/geologic records, current process observations, and future modeling studies). This approach of the ART Initiative will provide a means to better understand and predict change, particularly the consequences for biological productivity, and ultimate responses in the Arctic Ocean system. More information about the ART Initiative can be found at http://www.aosb.org/art.html.

  18. Modular arctic structures system

    SciTech Connect

    Reusswig, G. H.

    1984-12-04

    A modular and floatable offshore exploration and production platform system for use in shallow arctic waters is disclosed. A concrete base member is floated to the exploration or production site, and ballated into a predredged cavity. The cavity and base are sized to provide a stable horizontal base 30 feet below the mean water/ice plane. An exploration or production platform having a massive steel base is floated to the site and ballasted into position on the base. Together, the platform, base and ballast provide a massive gravity structure that is capable of resisting large ice and wave forces that impinge on the structure. The steel platform has a sloping hourglass profile to deflect horizontal ice loads vertically, and convert the horizontal load to a vertical tensile stress, which assists in breaking the ice as it advances toward the structure.

  19. The hydrological context determines the beta-diversity of aerobic anoxygenic phototrophic bacteria in European Arctic seas but does not favor endemism

    PubMed Central

    Lehours, Anne-Catherine; Jeanthon, Christian

    2015-01-01

    Despite an increasing number of studies over the last 15 years, aerobic anoxygenic photoheterotrophic (AAP) bacteria remain a puzzling functional group in terms of physiology, metabolism, and ecology. To contribute to a better knowledge of their environmental distribution, the present study aims at analyzing their diversity and structure at the boundary between the Norwegian, Greenland, and Barents Seas. The polymorphism of a marker gene encoding a sub-unit of the photosynthetic apparatus (pufM gene) was analyzed and attempted to be related to environmental parameters. The Atlantic or Arctic origin of water masses had a strong impact on the AAP bacterial community structure whose populations mostly belonged to the Alpha- and Gammaproteobacteria. A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions. Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently. We found that temperature is a major determinant of alpha diversity of AAP bacteria in this marine biome with specific clades emerging locally according to the partitioning of water masses. Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere. This observation highlights that the studied area does not favor AAP bacteria endemism but also opens new questions about the truthfulness of biogeographical patterns and on the extent of AAP bacterial diversity. PMID:26191046

  20. How will the greening of the Arctic affect an important prey species and disturbance agent? Vegetation effects on arctic ground squirrels.

    PubMed

    Wheeler, H C; Chipperfield, J D; Roland, C; Svenning, J-C

    2015-07-01

    Increases in terrestrial primary productivity across the Arctic and northern alpine ecosystems are leading to altered vegetation composition and stature. Changes in vegetation stature may affect predator-prey interactions via changes in the prey's ability to detect predators, changes in predation pressure, predator identity and predator foraging strategy. Changes in productivity and vegetation composition may also affect herbivores via effects on forage availability and quality. We investigated if height-dependent effects of forage and non-forage vegetation determine burrowing extent and activity of arctic ground squirrels (Urocitellus parryii). We collected data on burrow networks and activity of arctic ground squirrels across long-term vegetation monitoring sites in Denali National Park and Preserve, Alaska. The implications of height-specific cover of potential forage and non-forage vegetation on burrowing behaviour and habitat suitability for arctic ground squirrels were investigated using hierarchical Bayesian modelling. Increased cover of forbs was associated with more burrows and burrow systems, and higher activity of systems, for all forb heights. No other potential forage functional group was related to burrow distribution and activity. In contrast, height-dependent negative effects of non-forage vegetation were observed, with cover over 50-cm height negatively affecting the number of burrows, systems and system activity. Our results demonstrate that increases in vegetation productivity have dual, potentially counteracting effects on arctic ground squirrels via changes in forage and vegetation stature. Importantly, increases in tall-growing woody vegetation (shrubs and trees) have clear negative effects, whereas increases in forb should benefit arctic ground squirrels. PMID:25666700

  1. Role of Greenland meltwater in the changing Arctic

    NASA Astrophysics Data System (ADS)

    Dukhovskoy, Dmitry; Proshutinsky, Andrey; Timmermans, Mary-Louise; Myers, Paul; Platov, Gennady; Bamber, Jonathan; Curry, Beth; Somavilla, Raquel

    2016-04-01

    Observational data show that the Arctic ocean-ice-atmosphere system has been changing over the last two decades. Arctic change is manifest in the atypical behavior of the climate indices in the 21st century. Before the 2000s, these indices characterized the quasi-decadal variability of the Arctic climate related to different circulation regimes. Between 1948 and 1996, the Arctic atmospheric circulation alternated between anticyclonic circulation regimes and cyclonic circulation regimes with a period of 10-15 years. Since 1997, however, the Arctic has been dominated by an anticyclonic regime. Previous studies indicate that in the 20th century, freshwater and heat exchange between the Arctic Ocean and the sub-Arctic seas were self-regulated and their interactions were realized via quasi-decadal climate oscillations. What physical processes in the Arctic Ocean - sub-Arctic ocean-ice-atmosphere system are responsible for the observed changes in Arctic climate variability? The presented work is motivated by our hypothesis that in the 21st century, these quasi-decadal oscillations have been interrupted as a result of an additional freshwater source associated with Greenland Ice Sheet melt. Accelerating since the early 1990s, the Greenland Ice Sheet mass loss exerts a significant impact on thermohaline processes in the sub-Arctic seas. Surplus Greenland freshwater, the amount of which is about a third of the freshwater volume fluxed into the region during the 1970s Great Salinity Anomaly event, can spread and accumulate in the sub-Arctic seas influencing convective processes there. It is not clear, however, whether Greenland freshwater can propagate into the interior convective regions in the Labrador Sea and the Nordic Seas. In order to investigate the fate and pathways of Greenland freshwater in the sub-Arctic seas and to determine how and at what rate Greenland freshwater propagates into the convective regions, several numerical experiments using a passive tracer to

  2. Arctic Ocean outflow shelves in the changing Arctic: A review and perspectives

    NASA Astrophysics Data System (ADS)

    Michel, Christine; Hamilton, Jim; Hansen, Edmond; Barber, David; Reigstad, Marit; Iacozza, John; Seuthe, Lena; Niemi, Andrea

    2015-12-01

    Over the past decade or so, international research efforts, many of which were part of the International Polar Year, have accrued our understanding of the Arctic outflow shelves. The Arctic outflow shelves, namely the East Greenland Shelf (EGS) and the Canadian Arctic Archipelago (CAA), serve as conduits through which Arctic sea ice and waters and their properties are exported to the North Atlantic. These shelves play an important role in thermohaline circulation and global circulation patterns, while being influenced by basin-scale and regional changes taking place in the Arctic. Here, we synthesize the current knowledge on key forcings of primary production and ecosystem processes on the outflow shelves, as they influence their structure and functionalities and, consequently their role in Arctic Ocean productivity and global biogeochemical cycles. For the CAA, a fresh outlook on interannual and decadal physical and biological time-series reveals recent changes in productivity patterns, while an extensive analysis of sea ice conditions over the past 33 years (1980-2012) demonstrates significant declines in multi-year ice and a redistribution of ice types. For the EGS, our analysis shows that sea ice export strongly contributes to structuring spatially diverse productivity regimes. Despite the large heterogeneity in physical and biological processes within and between the outflow shelves, a conceptual model of productivity regimes is proposed, helping identify general productivity patterns and key forcings. The different productivity regimes are expected to respond differently to current and future Arctic change, providing a useful basis upon which to develop predictive scenarios of future productivity states. Current primary production estimates for both outflow shelves very likely underestimate their contribution to total Arctic production.

  3. Interdecadal changes in snow depth on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Webster, Melinda A.; Rigor, Ignatius G.; Nghiem, Son V.; Kurtz, Nathan T.; Farrell, Sinead L.; Perovich, Donald K.; Sturm, Matthew

    2014-08-01

    Snow plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and IceBridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.1 ± 9.4 to 22.2 ± 1.9 cm in the western Arctic, and from 32.8 ± 9.4 to 14.5 ± 1.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37 ± 29% in the western Arctic and 56 ± 33% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

  4. Arctic River Discharge and Sediment Loads --- an Overview

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Overeem, I.; Brakenridge, G. R.; Hudson, B.; Cohen, S.

    2014-12-01

    Evidence suggests that river discharge has been increasing (+10%) over the last 30 years (1977-2007) for most arctic rivers. The peak melt month occurs earlier in the season in 66% of the studied rivers. Cold season flow is also increasing. Satellite discharge estimates, daily, based on microwave radiometry, are now possible from 1998 onwards. Daily river discharge hindcasts over the last 60 years using the water balance model WBMsed at a 10km spatial resolution are now available. The WBMsed model can be used in forecast mode assuming valid input climatology. The challenge here has been the accuracy of sub-polar precipitation grids. While each of these three methods (gauging, orbital sensing, modeling) has temporal and spatial coverage limitations, the combination of all three methods provides for a realistic way forward for estimating local discharge across the pan arctic. Flood inundation products are routinely produced for the pan-arctic using automated mapping algorithms developed by the Dartmouth Flood Observatory. The determination of artic river sediment loads is less than ideal. Some rivers have only been monitored for a short number of years, and many have not been monitored at all. The WBMsed model is perhaps the best method of estimating the daily sediment flux to the Arctic Ocean, at least for rivers where the mean discharge is greater than 30 m3/s. Additionally there is limited-duration field monitoring by national surveys. New methods are being explored, including back calculating the delivery of sediment to the coastal ocean by plume dimensions observed from space (MODIS, LandSat). These methods have had moderate success when applied to plumes extending in the Greenland fjords. Canada maintains an active circa 7-y satellite program (ArcticNet) to track the Mackenzie discharge during the spring-summer runoff period when turbid river water is apt to flow under and over marginal sea ice in the Beaufort Sea.

  5. Arctic climate tipping points.

    PubMed

    Lenton, Timothy M

    2012-02-01

    There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points. PMID:22270703

  6. Prosodically-Conditioned Variability in Children's Production of French Determiners

    ERIC Educational Resources Information Center

    Demuth, Katherine; Tremblay, Annie

    2008-01-01

    Researchers have long noted that children's grammatical morphemes are variably produced, raising questions about when and how grammatical competence is acquired. This study examined the spontaneous production of determiners by two French-speaking children aged 1 ; 5-2 ; 5. It found that determiners were produced earlier with monosyllabic words,…

  7. A Simple Apparatus for Determining Ionization and Solubility Product Constants.

    ERIC Educational Resources Information Center

    Gerardi, Gary

    1977-01-01

    Describes a simple conductivity apparatus for the determination of ionization and solubility product constants of various substances. The uses of the apparatus in determining the ionization constant of a weak monoprotic acid and in measuring the rate of diffusion of ions through a membrane are also presented. (HM)

  8. 75 FR 24968 - Crepe Paper Products From China Determination

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... The Commission instituted this review on December 1, 2009 (74 FR ] 62815) and determined on March 8, 2010 that it would conduct an expedited review (75 FR 13779, March 23, 2010). The Commission... COMMISSION Crepe Paper Products From China Determination On the basis of the record \\1\\ developed in...

  9. Ice island creation, drift, recurrences, mechanical properties, and interactions with arctic offshore oil production structures. Final report

    SciTech Connect

    Sackinger, W.M.; Jeffries, M.O.; Li, Fucheng; Lu, Mingchi

    1991-03-01

    Research and engineering studies on first-year sea ice for over two decades has resulted in the design, construction, and operation of jacket platforms, of artificial islands, and of massive gravity structures which routinely withstand moving sea ice of thickness up to 2 meters. However, the less-common interactions between such structures and moving multiyear ice ({ge}3 meters thick), and also moving ice islands (10 to 60 meters thick) remain as the unknown and potentially most serious hazard for Arctic offshore structures. In this study, research was addressed across the complete span of remaining questions regarding such features. Ice island components, thickness distributions, scenarios and models for the interactions of massive ice features with offshore structures, all were considered. Ice island morphology and calving studies were directed at the cluster of 19 ice islands produced in a calving from the Ward Hunt Ice Shelf on Ellesmere Island in 1983, and also at a calving from the Milne Ice Shelf in 1988. The statistics of ice island dynamics, on both a short-term small-scale basis and also on a long-term basis, were studied. Typical wind velocities of 5 to 7.5 meters per second led to ice island speeds of about 0.014 of the wind speed, at an angle of 20{degrees} to the right of the wind direction. Ice island samples were tested for their stress/strain characteristics. Compressive strength values ranged from 1.64 MPa at a strain rate of 2 {times} 10{sup {minus}7} s{sup {minus}1} to 6.75 MPa at a strain rate of 1 {times} 10{sup {minus}3} s{sup {minus}1}. Scenarios for ice island/structure interactions were developed, and protective countermeasures such as spray ice and ice rubble barriers were suggested. Additional computer modeling of structure/ice interactions for massive ice features is recommended.

  10. Determination of silicon in petroleum products by ICP-AES

    SciTech Connect

    Salmon, S.G.; Williams, M.C.

    1994-12-31

    The determination of silicon in petroleum and related products is an important issue due to the effects it has in its various compound forms. Silicone fluids are used in many lubricants as foam inhibitors and serve a vital function as performance additives. Likewise, silicates are used in coolant formulations. The beneficial effects of these additives can be seen at very low treatment levels. Silicon can also occur as an unwanted contaminant in refined products as carryover of foam inhibitor used in refinery units or as silica deposited as fines from catalyst supports. Silicon compounds can poison refinery catalysts and their presence in certain products can ruin machinery. Traditionally, the presence of foam inhibitor in lubricants has been indicated by a foam test (ASTMD 8924P 146) rather than by spectroscopic determination of silicon. Aspects of determining silicon by inductively coupled plasma atomic emission spectroscopy in petroleum and related products will be presented.

  11. Late Pleistocene and Holocene meltwater events in the western Arctic Ocean

    USGS Publications Warehouse

    Poore, R.Z.; Osterman, L.; Curry, W.B.; Phillips, R.L.

    1999-01-01

    Accelerator mass spectrometer 14C dated stable isotope data from Neogloboquadrina pachyerma in cores raised from the Mendeleyev Ridge and slope provide evidence for significant influx of meltwater to the western Arctic Ocean during the early part of marine oxygen isotope stage 1 (OIS 1) and during several intervals within OIS 3. The strongest OIS 3 meltwater event occurred before ca. 45 ka (conventional radiocarbon age) and was probably related to the deglaciation at the beginning of OIS 3. Major meltwater input to the western Arctic Ocean during the last deglaciation coincides closely with the maximum rate of global sea-level rise as determined from the Barbados sea-level record, demonstrating a strong link between the global record and changes in the central Arctic Ocean. OIS 2, which includes the last glacial maximum, is very condensed or absent in the cores. Abundance and ??13C values for N. pachyderma in the middle part of OIS 3 are similar to modern values, indicating high productivity and seasonal ice-free areas along the Arctic margin at that time. These records indicate that the Arctic Ocean was a source of heat and moisture to the northern polar atmosphere during parts of OIS 3.

  12. ArcticDEM; A Publically Available, High Resolution Elevation Model of the Arctic

    NASA Astrophysics Data System (ADS)

    Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Bates, Brian; Willamson, Cathleen; Peterman, Kennith

    2016-04-01

    A Digital Elevation Model (DEM) of the Arctic is needed for a large number of reasons, including: measuring and understanding rapid, ongoing changes to the Arctic landscape resulting from climate change and human use and mitigation and adaptation planning for Arctic communities. The topography of the Arctic is more poorly mapped than most other regions of Earth due to logistical costs and the limits of satellite missions with low-latitude inclinations. A convergence of civilian, high-quality sub-meter stereo imagery; petascale computing and open source photogrammetry software has made it possible to produce a complete, very high resolution (2 to 8-meter posting), elevation model of the Arctic. A partnership between the US National Geospatial-intelligence Agency and a team led by the US National Science Foundation funded Polar Geospatial Center is using stereo imagery from DigitalGlobe's Worldview-1, 2 and 3 satellites and the Ohio State University's Surface Extraction with TIN-based Search-space Minimization (SETSM) software running on the University of Illinois's Blue Water supercomputer to address this challenge. The final product will be a seemless, 2-m posting digital surface model mosaic of the entire Arctic above 60 North including all of Alaska, Greenland and Kamchatka. We will also make available the more than 300,000 individual time-stamped DSM strip pairs that were used to assemble the mosaic. The Arctic DEM will have a vertical precision of better than 0.5m and can be used to examine changes in land surfaces such as those caused by permafrost degradation or the evolution of arctic rivers and floodplains. The data set can also be used to highlight changing geomorphology due to Earth surface mass transport processes occurring in active volcanic and glacial environments. When complete the ArcticDEM will catapult the Arctic from the worst to among the best mapped regions on Earth.

  13. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Haekkinen, S.

    2000-01-01

    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 I 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 to determine significant forcing patterns of sea ice and high-latitude variability.

  14. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    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.

  15. Arctic science input wanted

    NASA Astrophysics Data System (ADS)

    The Arctic Research and Policy Act (Eos, June 26, 1984, p. 412) was signed into law by President Ronald Reagan this past July. One of its objectives is to develop a 5-year research plan for the Arctic. A request for input to this plan is being issued this week to nearly 500 people in science, engineering, and industry.To promote Arctic research and to recommend research policy in the Arctic, the new law establishes a five-member Arctic Research Commission, to be appointed by the President, and establishes an Interagency Arctic Research Policy Committee, to be composed of representatives from nearly a dozen agencies having interests in the region. The commission will make policy recommendations, and the interagency committee will implement those recommendations. The National Science Foundation (NSF) has been designated as the lead agency of the interagency committee.

  16. Glasnost in the Arctic

    NASA Astrophysics Data System (ADS)

    Roederer, Juan

    The question of establishing an international body to coordinate research activities in the Arctic is an old one. Proposals have been formulated on several occasions during the last 3 decades, but they have never been implemented.At present, a few adhoc or semiprivate bodies are engaged in cooperative ventures of arctic research, and there are several bilateral programs between Arctic countries. Yet there is no northern equivalent to the Scientific Committee on Antarctic Research (SCAR) o f the International Council of Scientific Unions (ICSU). The politically and strategically sensitive nature of the Arctic regions has been a seemingly insurmountable obstacle. Recently, however, an international initiative spearheaded by the U.S. Arctic Research Commission led to promising developments regarding international scientific cooperation in the Arctic.

  17. Arctic soil microbial diversity in a changing world.

    PubMed

    Blaud, Aimeric; Lerch, Thomas Z; Phoenix, Gareth K; Osborn, A Mark

    2015-12-01

    The Arctic region is a unique environment, subject to extreme environmental conditions, shaping life therein and contributing to its sensitivity to environmental change. The Arctic is under increasing environmental pressure from anthropogenic activity and global warming. The unique microbial diversity of Arctic regions, that has a critical role in biogeochemical cycling and in the production of greenhouse gases, will be directly affected by and affect, global changes. This article reviews current knowledge and understanding of microbial taxonomic and functional diversity in Arctic soils, the contributions of microbial diversity to ecosystem processes and their responses to environmental change. PMID:26275598

  18. [Horse, cow and reindeer were converted into arctic domestic animals].

    PubMed

    Kantanen, Juha

    2016-01-01

    Domestic animal production in the arctic region is often thought to be based exclusively on reindeer herding. There are, however, regions in Northern Europe and Siberia having a long tradition in rearing breeds of cattle and horse adapted to the northers conditions also. The development of these arctic animal breeds has been largely founded on old tradition rather than on the programs of breeding organizations. As a result of the selection carried out by nature and man, the domestic animals of arctic regions express characteristics that are metabolic, structural, associated with reproductive physiology and conducive to the adaptation to arctic conditions. PMID:27522831

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2015-03-15

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

  1. [Energy flow in arctic aquatic ecosystems

    SciTech Connect

    Schell, D.M.

    1985-12-31

    This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

  2. [Energy flow in arctic aquatic ecosystems

    SciTech Connect

    Schell, D.M.

    1985-01-01

    This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

  3. Arctic Climate Change: A Tale of Two Cod Species

    EPA Science Inventory

    Arctic cod play an important role in the Arctic trophic hierarchy as the consumer of primary productivity and a food source for many marine fish and mammals. Shifts in their distribution and abundance could have cascading affects in the marine environment. This paper investigates...

  4. White Arctic vs. Blue Arctic: Making Choices

    NASA Astrophysics Data System (ADS)

    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.

  5. 40 CFR 600.511-08 - Determination of domestic production.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Determination of domestic production. 600.511-08 Section 600.511-08 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Procedures...

  6. Some Recent Secondary Production Measurements for Neutrino Flux Determination

    NASA Astrophysics Data System (ADS)

    Mills, Geoffrey B.

    2011-12-01

    Recent measurements of meson production in proton-nucleus interactions have made possible reliable neutrino flux determinations at modern neutrino experiments. This article discusses preliminary results from the HARP, MIP, and E910 are discussed along with some of their implications for the MINOS, K2K, and MiniBooNE neutrino experiments.

  7. Determining host suitability of pecan for stored-product insects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A no-choice test was performed to determine survival and reproductive capacity of stored-product insect pests on pecan, Carya illinoensis (Wangenheim) Koch. Insects used were Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae); sawtoothed grain beetle, Oryzaephilus surinamensis...

  8. Entropy production determination of the ambipolar solution nearest equilibrium

    SciTech Connect

    Catto, P.J.; Myra, J.R.

    1984-10-01

    A general derivation of the steady state entropy production equation is presented for a confined plasma which loses particles and energy via radial transport and, perhaps, end loss. The resulting equation is employed to determine which root or solution is closest to thermodynamic equilibrium when more than one self-consistent or ambipolar solution is possible.

  9. Observing the Arctic Ocean under melting ice - the UNDER-ICE project

    NASA Astrophysics Data System (ADS)

    Sagen, Hanne; Ullgren, Jenny; Geyer, Florian; Bergh, Jon; Hamre, Torill; Sandven, Stein; Beszczynska-Möller, Agnieszka; Falck, Eva; Gammelsrød, Tor; Worcester, Peter

    2014-05-01

    The sea ice cover of the Arctic Ocean is gradually diminishing in area and thickness. The variability of the ice cover is determined by heat exchange with both the atmosphere and the ocean. A cold water layer with a strong salinity gradient insulates the sea ice from below, preventing direct contact with the underlying warm Atlantic water. Changes in water column stratification might therefore lead to faster erosion of the ice. As the ice recedes, larger areas of surface water are open to wind mixing; the effect this might have on the water column structure is not yet clear. The heat content in the Arctic strongly depends on heat transport from other oceans. The Fram Strait is a crucial pathway for the exchange between the Arctic and the Atlantic Ocean. Two processes of importance for the Arctic heat and freshwater budget and the Atlantic meridional overturning circulation take place here: poleward heat transport by the West Spitzbergen Current and freshwater export by the East Greenland Current. A new project, Arctic Ocean under Melting Ice (UNDER-ICE), aims to improve our understanding of the ocean circulation, water mass distribution, fluxes, and mixing processes, sea ice processes, and net community primary production in ice-covered areas and the marginal ice zone in the Fram Strait and northward towards the Gakkel Ridge. The interdisciplinary project brings together ocean acoustics, physical oceanography, marine biology, and sea ice research. A new programme of observations, integrated with satellite data and state-of-the-art numerical models, will be started in order to improve the estimates of heat, mass, and freshwater transport between the North Atlantic and the Arctic Ocean. On this poster we present the UNDER-ICE project, funded by the Research Council of Norway and GDF Suez E&P Norge AS for the years 2014-2017, and place it in context of the legacy of earlier projects in the area, such as ACOBAR. A mooring array for acoustic tomography combined with

  10. Arctic circulation regimes.

    PubMed

    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. PMID:26347536

  11. Arctic circulation regimes

    PubMed Central

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

    2015-01-01

    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. PMID:26347536

  12. Emissions from International Shipping in the Arctic

    NASA Astrophysics Data System (ADS)

    Corbett, J. J.; Winebrake, J. J.; Gold, M.; Harder, S.

    2008-12-01

    with more regional impact include NOx, SOx, CO, and PM. For these pollutants Arctic shipping emissions are small contributors to global inventories on a mass basis. For example, Arctic shipping accounts for about 62,400 tonnes per year of NOX pollution in the Arctic region, about 0.3 percent of 25.6 Tg of NOx (as NO2, or 7.8 Tg as N in 2007) global ship NOx emissions. Future trends toward increased international shipping in the Arctic will increase these numbers proportional to the increased traffic, although future research is needed to determine whether the increased climate-scale impacts would be proportional to Arctic shipping activity. Previous research (Granier et al, GRL 2006) indicated that shipping growth could account for an additional 0.65 to 1.3 million Tg N from Arctic shipping (2.5 Tg to 4.9 Tg NOx as NO2). Using our preliminary inventory results, this corresponds to between 40 and 70 times more Arctic shipping activity in 2050 than in 2004, representing annually compounding growth rates in the range of 8 to 10 percent. We will present our inventory and discuss data quality needs to better reduce the uncertainty in Arctic shipping inventories.

  13. Comparison of produced water toxicity to Arctic and temperate species.

    PubMed

    Camus, L; Brooks, S; Geraudie, P; Hjorth, M; Nahrgang, J; Olsen, G H; Smit, M G D

    2015-03-01

    Produced water is the main discharge stream from oil and gas production. For offshore activities this water is usually discharged to the marine environment. Produced water contains traces of hydrocarbons such as polycyclic aromatic hydrocarbons as well as alkylphenols, which are relatively resistant to biodegradation and have been reported to cause adverse effects to marine organisms in laboratory studies. For management of produced water, risk-based tools have been developed using toxicity data for mainly non-Arctic species. Reliable risk assessment approaches for Arctic environments are requested to manage potential impacts of produced water associated with increased oil and gas activities in Arctic regions. In order to assess the applicability of existing risk tools for Arctic areas, basic knowledge on the sensitivity of Arctic species has to be developed. In the present study, acute and chronic toxicity of artificial produced water for 6 Arctic and 6 temperate species was experimentally tested and evaluated. The hazardous concentrations affecting 5% and 50% of the species were calculated from species sensitivity distribution curves. Hazardous concentrations were compared to elucidate whether temperate toxicity data used in risk assessment are sufficiently representative for Arctic species. From the study it can be concluded that hazardous concentration derived from individual species' toxicity data of temperate and Arctic species are comparable. However, the manner in which Arctic and non-Arctic populations and communities respond to exposure levels above established thresholds remains to be investigated. Hence, responses at higher levels of biological organization should be studied to reveal potential differences in sensitivities to produced water between Arctic and non-Arctic ecosystems. PMID:25521339

  14. Determination of estriol, estradiol, estrone, and progesterone in cosmetic products.

    PubMed

    Hubinger, Jean C

    2015-01-01

    This report describes the development and validation of a reverse phase high-performance liquid chromatography (HPLC) method with UV detection for the determination of the hormones estriol, estradiol, estrone, and progesterone in topically applied products. The developed method was then used to conduct a postmarket survey of consumer products for these hormones. Each product was first mixed with Celite and then extracted with methanol. Extracts were cleaned on a Waters Oasis HLB solid phase extraction cartridge, and then analyzed using reversed phase HPLC. The analytes were separated using an Agilent Zorbax Eclipse XDB C8 (5 μm, 250 mm by 4.6 mm) analytical column and detected by their absorbance at 230 nm. Chromatographic separation was achieved by a 1.0-ml/min linear gradient from 30% acetonitrile and 70% water to 80% acetonitrile and 20% water over 30 min. A final 5 min hold time and a re-equilibration time of 10 min were used to prepare the column for subsequent analysis. Recovery from two different brand lotions spiked with three different levels of estriol, estradiol, estrone, and progesterone ranged from 81.8% to 101%. In this study, a total of 70 cosmetic products were surveyed. Twenty two (63%) of the 35 products were labeled as containing an estrogen and/ or progesterone and also provided quantitative label information about the hormone ingredient. The most frequently labeled hormones were progesterone (66%), estriol (46%), estradiol (11%), and estrone (6%). Six products labeled as containing estriol were found to contain estradiol. An estrogen and/or progesterone were found in 34 products at concentrations ranging from 86.0 to 26,800 μg/g. Progesterone was not found in one product labeled as containing this hormone. An additional 35 products, which did not list hormones on their labels, were analyzed and estrogen or progesterone was not detected in these products. PMID:26454975

  15. Ice-Free Arctic Ocean?

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and researchers were unable to identify any natural processes that might slow the deicing of the Arctic. "What really makes the Arctic different from…

  16. Arctic Coastal Dynamics (ACD)

    NASA Astrophysics Data System (ADS)

    Rachold, V.; Boike, J.

    2003-04-01

    Coastal dynamics directly reflecting the complicated land-ocean interactions play an important role in the balance of sediments, organic carbon and nutrients in the Arctic basin. Recent studies indicate that sediment input to the Arctic shelves resulting from erosion of ice-rich, permafrost-dominated coasts may be equal to or greater than input from river discharge. Thus, the understanding and quantification of coastal processes is critical for interpreting the geological history of the Arctic shelves. The predictions of future behavior of these coasts in response to climatic and sea level changes is an important issue because most of the human activity that occurs at high latitudes concentrates on the Arctic coastlines. As an initiative of the International Permafrost Association (IPA) the multi-disciplinary, multi-national forum Arctic Coastal Dynamics (ACD), which was recently accepted as a project of the International Arctic Sciences Committee (IASC), had been developed. The overall objective of ACD is to improve our understanding of circum-Arctic coastal dynamics as a function of environmental forcing, coastal geology and cryology and morphodynamic behavior. In particular, the project aims to: - establish the rates and magnitudes of erosion and accumulation of Arctic coasts; - develop a network of long-term monitoring sites including local community-based observational sites; - identify and undertake focused research on critical processes; - estimate the amount of sediments and organic carbon derived from coastal erosion; - refine and apply an Arctic coastal classification (includes ground-ice, permafrost, geology etc.) in digital form (GIS format); - extract and utilize existing information on relevant environmental forcing parameters (e.g. wind speed, sea level, fetch, sea ice etc.); - produce a series of thematic and derived maps (e.g. coastal classification, ground-ice, sensitivity etc.); - develop empirical models to assess the sensitivity of Arctic

  17. Metagenomic evidence for sulfur lithotrophy by Epsilonproteobacteria as the major energy source for primary productivity in a sub-aerial arctic glacial deposit, Borup Fiord Pass

    PubMed Central

    Wright, Katherine E.; Williamson, Charles; Grasby, Stephen E.; Spear, John R.; Templeton, Alexis S.

    2013-01-01

    We combined free enenergy calculations and metagenomic analyses of an elemental sulfur (S0) deposit on the surface of Borup Fiord Pass Glacier in the Canadian High Arctic to investigate whether the energy available from different redox reactions in an environment predicts microbial metabolism. Many S, C, Fe, As, Mn, and NH4+ oxidation reactions were predicted to be energetically feasible in the deposit, and aerobic oxidation of S0 was the most abundant chemical energy source. Small subunit ribosomal RNA (SSU rRNA) gene sequence data showed that the dominant phylotypes were Sulfurovum and Sulfuricurvum, both Epsilonproteobacteria known to be capable of sulfur lithotrophy. Sulfur redox genes were abundant in the metagenome, but sox genes were significantly more abundant than reverse dsr (dissimilatory sulfite reductase)genes. Interestingly, there appeared to be habitable niches that were unoccupied at the depth of genome coverage obtained. Photosynthesis and NH4+ oxidation should both be energetically favorable, but we found few or no functional genes for oxygenic or anoxygenic photosynthesis, or for NH4+ oxidation by either oxygen (nitrification) or nitrite (anammox). The free energy, SSU rRNA gene and quantitative functional gene data are all consistent with the hypothesis that sulfur-based chemolithoautotrophy by Epsilonproteobacteria (Sulfurovum and Sulfuricurvum) is the main form of primary productivity at this site, instead of photosynthesis. This is despite the presence of 24-h sunlight, and the fact that photosynthesis is not known to be inhibited by any of the environmental conditions present. This is the first time that Sulfurovum and Sulfuricurvum have been shown to dominate a sub-aerial environment, rather than anoxic or sulfidic settings. We also found that Flavobacteria dominate the surface of the sulfur deposits. We hypothesize that this aerobic heterotroph uses enough oxygen to create a microoxic environment in the sulfur below, where the

  18. Entropy production determination of the ambipolar solution nearest equilibrium. Revision

    SciTech Connect

    Catto, P.J.; Myra, J.R.

    1985-05-01

    A general derivation of the steady state entropy production equation is presented for a confined plasma which loses particles and energy via radial transport and, perhaps, end loss. The resulting equation is employed to determine which root or solution at each pressure surface is closest to local thermodynamic equilibrium when more than one self-consistent or ambipolar solution is possible. The solution closest to local thermodynamic equilibrium is presumed to be the one with the smallest total collisional entropy production rate. This solution makes the distribution functions as close to local Maxwellians as possible.

  19. Method of determining forest production from remotely sensed forest parameters

    DOEpatents

    Corey, J.C.; Mackey, H.E. Jr.

    1987-08-31

    A method of determining forest production entirely from remotely sensed data in which remotely sensed multispectral scanner (MSS) data on forest 5 composition is combined with remotely sensed radar imaging data on forest stand biophysical parameters to provide a measure of forest production. A high correlation has been found to exist between the remotely sensed radar imaging data and on site measurements of biophysical 10 parameters such as stand height, diameter at breast height, total tree height, mean area per tree, and timber stand volume.

  20. Arctic polynyas

    NASA Astrophysics Data System (ADS)

    Alexander, Vera; Muench, Robin

    Polynyas are areas of open water that occur at specific, recurrent locations in the polar regions and that are surrounded by ice-covered waters. They have been of interest historically because they are centers of upper trophic level biological activity and were consequently foci of both commercial whaling activities and of native subsistence hunting. They have more recently become of interest from a basic research viewpoint because they are typified by intensive biological activity and energetic physical processes. They are similar, in many respects, to the marginal ice zones, which are an ongoing focus of considerable oceanographic research. Polynyas can be conceptually envisaged as polar oceanic “oases” in which biological activities are focused locally while they are surrounded by relatively unproductive waters. Polynyas serve as outposts of enhanced production within the pack ice remote from the biologically rich marginal ice zones.

  1. Role of Atmospheric Transport on the Arctic Amplification: Adjusting Role

    NASA Astrophysics Data System (ADS)

    KUG, J.; Yim, B.; Jin, F.

    2013-12-01

    It is controversial whether the atmospheric transport plays a role in arctic amplification. Recently, Hwang et al. (2011) showed that the magnitude of the arctic amplification is negatively correlated with anomalous poleward atmospheric transport. That is, when the arctic amplification is strong (weak), the atmospheric transport plays a negative (positive) role in the arctic amplification. In this study, it is discussed what is a physical mechanism to determine the role of atmospheric transport and relation with the arctic amplification. Here, we suggest adjusting roles of atmospheric transport. The strength of local feedback over the Arctic determines zonal wind changes. The zonal wind changes are determined by two factors. The first one is polar cap cooling, and second is surface warming. They play opposite roles. So, there will be two different zonal wind responses in high-latitude to the greenhouse warming. Depending on the zonal wind response, the atmospheric transport can play a different role because the zonal wind changes can organize synoptic eddy feedbacks including heat flux, which largely contributes to poleward energy transport. We show here that when polar cap cooling is strong, and surface warming over Arctic is relatively weak, the Jet stream tends to be shifted poleward, so it leads to poleward atmospheric transport. On the other hand, when the surface warming is too strong, it lead to southward shift of Jet stream and equatorward atmospheric transport, which paly a negative role in the Arctic amplification.

  2. Chytrids dominate arctic marine fungal communities.

    PubMed

    Hassett, B T; Gradinger, R

    2016-06-01

    Climate change is altering Arctic ecosystem structure by changing weather patterns and reducing sea ice coverage. These changes are increasing light penetration into the Arctic Ocean that are forecasted to increase primary production; however, increased light can also induce photoinhibition and cause physiological stress in algae and phytoplankton that can favour disease development. Fungi are voracious parasites in many ecosystems that can modulate the flow of carbon through food webs, yet are poorly characterized in the marine environment. We provide the first data from any marine ecosystem in which fungi in the Chytridiomycota dominate fungal communities and are linked in their occurrence to light intensities and algal stress. Increased light penetration stresses ice algae and elevates disease incidence under reduced snow cover. Our results show that chytrids dominate Arctic marine fungal communities and have the potential to rapidly change primary production patterns with increased light penetration. PMID:26754171

  3. Arctic and offshore research. Technology status report

    SciTech Connect

    Not Available

    1984-10-01

    The DOE Arctic and Offshore Research (AOR) effort is designed to meet the needs for a centralized, high-quality, Arctic energy-related data base and for long-term, high-risk research. The ultimate purpose of the DOE effort is to promote extensive private use of the evolving AOR technology data base in order to accelerate development of Arctic oil and gas resources. In assessing the Arctic energy-related research needs as delineated in this report, the Morgantown Energy Technology Center (METC), with the DOE Fossil Energy Office of Oil, Gas, and Shale Technology, developed the following activities: AOR Energy-Related Technology Data Base Development; AOR Seminars and Workshops; Arctic and Offshore Energy Research Coordination; Sea Ice Research; Seafloor/Soils Research; and Subice Systems Development. The DOE AOR effort was initiated in FY 1983, the early development activities were performed in January and February 1983, and the effort evolved to its present form by the conclusion of FY 1984. The current activities have included determining the Arctic bibliographic data base and initiating most pieces of the research described above (except multiyear ice properties and pipeline research). Some of the FY 1984 major accomplishments are: four to five ice islands 1 to 2 miles in length drifting off the Ellesmere ice shelves north of Ellesmere Island were aerially surveyed. A report was completed on the location of the ice shelf edge, breakup, and regrowth of the Ellesmere ice shelves over the past two decades. Ice-ridging shear zone studies have shown that the 6- to 10-feet high shoals usually under the shear zone are not totally destroyed from ice gouging from one year to the next, but that the ice gouging may be instrumental in initiating and maintaining the shoals, which may protect Arctic offshore structures. Airborne radar sensing techniques were used to determine the electromagnetic properties of sea ice and physical properties.

  4. Simulated and observed trends in key variables of the Arctic marine carbon cycle

    NASA Astrophysics Data System (ADS)

    Goris, Nadine; Heinze, Christoph; Lauvset, Siv; Petrenko, Dmitry; Pozdnyakov, Dmitry; Schwinger, Jörg

    2013-04-01

    nor to determine significant trends. Widespread measurements for at least 40 years are needed to capture both different regional behavior and associated trends stressing the value of the existing spatially comprehensive Arctic datasets of primary production and the importance of continuing the sensor-retrievals in the following years. The measurement stations of atmospheric CO2 provide a good characterization of CO2 with continuous measurement on a few, well distributed locations and allow for a confident data-model comparison all over the Arctic, while the coverage of the LDEO/SOCAT database allows for confident statements about the trends of oceanic pCO2 in the region between 60oW and 30oE. Here, the validated model MICOM-HAMOCC-M simulates a fast rising oceanic CO2 partial pressure leading to an accelerated decrease in ocean CO2 uptake in the Arctic.

  5. Atmospheric DMS and Biogenic Sulfur aerosol measurements in the Arctic

    NASA Astrophysics Data System (ADS)

    Ghahremaninezhadgharelar, R.; Norman, A. L.; Wentworth, G.; Burkart, J.; Leaitch, W. R.; Abbatt, J.; Sharma, S.; Desiree, T. S.

    2014-12-01

    Dimethyl Sulfide (DMS) and its oxidation products were measured on the board of the Canadian Coast Guard Ship (CCGS) Amundsen and above melt ponds in the Arctic during July 2014 in the context of the NETCARE study which seeks to understand the effect of DMS and its oxidation products with respect to aerosol nucleation, as well as its effect on cloud and precipitation properties. The objective of this study is to quantify the role of DMS in aerosol growth and activation in the Arctic atmosphere. Atmospheric DMS samples were collected from different altitudes, from 200 to 9500 feet, aboard the POLAR6 aircraft expedition to determine variations in the DMS concentration and a comparison was made to shipboard DMS measurements and its effects on aerosol size fractions. The chemical and isotopic composition of sulfate aerosol size fractions was studied. Sulfur isotope ratios (34S/32S) offer a way to determine the oceanic DMS contribution to aerosol growth. The results are expected to address the contribution of anthropogenic as well as biogenic sources of aerosols to the growth of the different aerosol size fractions. In addition, aerosol sulfate concentrations were measured at the same time within precipitation and fogs to compare with the characteristics of aerosols in each size fraction with the characteristics of the sulfate in each medium. This measurement is expected to explain the contribution of DMS oxidation in aerosol activation in the Arctic summer. Preliminary results from the measurement campaign for DMS and its oxidation products in air, fog and precipitation will be presented.

  6. Boreal fire influence on Arctic tropospheric ozone, ecosystems and climate forcing

    NASA Astrophysics Data System (ADS)

    Arnold, S.; Monks, S. A.; Emmons, L. K.; Sitch, S.; Rap, A.; Law, K.; Tilmes, S.; Lamarque, J.

    2013-12-01

    Temperature observations show that the Arctic has warmed rapidly in the past few decades compared to the northern hemisphere as a whole. Model calculations suggest that changes in short-lived pollutants such as ozone and aerosol may have contributed significantly to this warming. Arctic tropospheric budgets of short-lived pollutants are impacted by both local anthropogenic emissions and by long-range transport of gases and aerosols from Europe, Asia and N. America, but also by local Boreal wildfires in summer. Our understanding of how fires impact Arctic budgets of climate-relevant atmospheric constituents is limited, and is reliant on sparse observations and models of tropospheric chemistry. A better understanding of Boreal fire influence on Arctic ozone is essential for improving the reliability of our projections of future Arctic and Northern Hemisphere climate change, especially in light of proposed climate-fire feedbacks which may enhance the intensity and extent of high latitude wildfire under a warming climate. Using the NCAR Community Earth System Model (CESM) and a scheme for tagging and tracking NOx emitted by high latitude wildfires and its resultant tropospheric ozone production, we investigate the impacts of fire-sourced ozone on summertime high latitude radiative forcing and on ecosystems. The large fraction of NOy present as PAN in the Arctic suggests there may be a strong sensitivity of NOy and ozone enhancement to the efficiency of vertical transport from source regions, which determines the stability of PAN as air is advected poleward. We use these simulations and aircraft observations to characterise the vertical distributions of sensitivities of Arctic NOy and ozone to remote anthropogenic and local widlfire sources, and use an offline radiative transfer model to quantify impacts on local ozone radiative forcing. We compare these vertical sensitivities with those of a primary-emitted CO-like source tracer, to investigate the role of PAN

  7. [Determination of Butroxydim in Agricultural Products by LC-MS].

    PubMed

    Minatani, Tomiaki; Nagai, Hiroyuki; Tada, Hiroyuki; Goto, Kotaro; Nemoto, Satoru

    2015-01-01

    An analytical method for the determination of butroxydim in agricultural products by LC-MS was developed. Butroxydim was extracted with acetonitrile and an aliquot of the crude extract was cleaned up on an octadecyl silanized silica gel (C18) cartridge column (1,000 mg), followed by a salting-out step to remove water. Before purification on a silica gel (SI) cartridge column (690 mg), polar matrices were precipitated by adding ethyl acetate, n-hexane and anhydrous sodium sulfate successively. This process effectively removed caffeine and catechins and improved recovery when analyzing residual butroxydim in tea leaves. Recovery and repeatability were good; the relative standard deviations were less than 5% for all 12 tested agricultural products (brown rice, soybean, potato, spinach, cabbage, apple, orange, grapefruit, lemon, tomato, peas with pods, and tea). Average recoveries for 11 agricultural products, except for lemon, were 74-92%. PMID:26699270

  8. TOPEX/Poseidon precision orbit determination production and expert system

    NASA Technical Reports Server (NTRS)

    Putney, Barbara; Zelensky, Nikita; Klosko, Steven

    1993-01-01

    TOPEX/Poseidon (T/P) is a joint mission between NASA and the Centre National d'Etudes Spatiales (CNES), the French Space Agency. The TOPEX/Poseidon Precision Orbit Determination Production System (PODPS) was developed at Goddard Space Flight Center (NASA/GSFC) to produce the absolute orbital reference required to support the fundamental ocean science goals of this satellite altimeter mission within NASA. The orbital trajectory for T/P is required to have a RMS accuracy of 13 centimeters in its radial component. This requirement is based on the effective use of the satellite altimetry for the isolation of absolute long-wavelength ocean topography important for monitoring global changes in the ocean circulation system. This orbit modeling requirement is at an unprecedented accuracy level for this type of satellite. In order to routinely produce and evaluate these orbits, GSFC has developed a production and supporting expert system. The PODPS is a menu driven system allowing routine importation and processing of tracking data for orbit determination, and an evaluation of the quality of the orbit so produced through a progressive series of tests. Phase 1 of the expert system grades the orbit and displays test results. Later phases undergoing implementation, will prescribe corrective actions when unsatisfactory results are seen. This paper describes the design and implementation of this orbit determination production system and the basis for its orbit accuracy assessment within the expert system.

  9. Beneath the Arctic Green: Have recent increases in plant production been offset by increases in soil decomposition?

    NASA Astrophysics Data System (ADS)

    Harden, J. W.; O'Donnell, J.; Fuller, C.; Sierra, C. A.; Johnson, K. D.; Manies, K.; Jorgenson, T.; Jones, M.; Ewing, S. A.; Yue, C.; Turetsky, M.

    2013-12-01

    Observational and modeling studies suggest that boreal vegetation has undergone an increase in plant production and C uptake in recent decades, coincident with increases in regional air temperatures, atmospheric CO2 concentration, and fire/successional dynamics. In the North American boreal forest, wildfires have increased in extent, season length, and depth of burn, driving higher C emission from black spruce ecosystems. Meanwhile, responses in soil systems that dictate the net ecosystem carbon (C) balance are less well known, in part owing to problems with elucidating the relatively small signals of organic matter decomposition from the large C fluxes of gross primary production and ecosystem respiration. Here, we measured net C accumulation in soils from Interior Alaska using radiocarbon (14C), lead isotopes (210Pb), cesium isotopes (137Cs), and time sequences of forest regeneration (fire and thaw chronosequences). We use soil 14C and non-steady-state models to estimate turnover times for soil organic C. Over the past century, rates of soil C uptake based on upland chronosequences ranged from -20 to -30 g C/m2/yr, but regionally likely shifted toward a reduced sink or source of - 20 to + 10 g C/m2/yr in recent decades due to increased combustion losses and deep C mobilization associated with permafrost thaw. C accumulation rates in lowland thermokarst chronosequences suggest a mixed sink/source effect, with post-thaw increases in surface accumulation potentially offset by decomposition at depth, or enhanced initial decomposition of C from previously frozen soils, followed by long-term net uptake of post-thaw peat. Large uncertainties remain regarding the turnover of soil organic C in boreal soil, yet enhanced decomposition has likely offset the increase in NPP, resulting in a reduced sink activity relative to pre1960s.

  10. Structure Determination of Natural Products by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Biemann, Klaus

    2015-07-01

    I review laboratory research on the development of mass spectrometric methodology for the determination of the structure of natural products of biological and medical interest, which I conducted from 1958 to the end of the twentieth century. The methodology was developed by converting small peptides to their corresponding polyamino alcohols to make them amenable to mass spectrometry, thereby making it applicable to whole proteins. The structures of alkaloids were determined by analyzing the fragmentation of a known alkaloid and then using the results to deduce the structures of related compounds. Heparin-like structures were investigated by determining their molecular weights from the mass of protonated molecular ions of complexes with highly basic, synthetic peptides. Mass spectrometry was also employed in the analysis of lunar material returned by the Apollo missions. A miniaturized gas chromatograph mass spectrometer was sent to Mars on board of the two Viking 1976 spacecrafts.

  11. Structure Determination of Natural Products by Mass Spectrometry.

    PubMed

    Biemann, Klaus

    2015-01-01

    I review laboratory research on the development of mass spectrometric methodology for the determination of the structure of natural products of biological and medical interest, which I conducted from 1958 to the end of the twentieth century. The methodology was developed by converting small peptides to their corresponding polyamino alcohols to make them amenable to mass spectrometry, thereby making it applicable to whole proteins. The structures of alkaloids were determined by analyzing the fragmentation of a known alkaloid and then using the results to deduce the structures of related compounds. Heparin-like structures were investigated by determining their molecular weights from the mass of protonated molecular ions of complexes with highly basic, synthetic peptides. Mass spectrometry was also employed in the analysis of lunar material returned by the Apollo missions. A miniaturized gas chromatograph mass spectrometer was sent to Mars on board of the two Viking 1976 spacecrafts. PMID:26161970

  12. Determining Suitable Areas for More Efficient Hazelnut Production

    NASA Astrophysics Data System (ADS)

    Saralioglu, E.; Yildirim, D.; Gungor, O.

    2016-06-01

    Turkey is the largest hazelnut producer and exporter in the world with approximately 75% worldwide production and 70-75% of world exports, yet according to FAO; annual yield gain rate is significantly lower than Italy and USA. While Turkey produces 0.94 ton/hectare hazelnut, average yield rates for USA, Italy and Spain are 2.6 ton/hectare, 1.68 ton/hectare and 1 ton/hectare, respectively. Hazelnut production in Turkey is primarily concentrated along Black Sea coast centered Giresun and Trabzon provinces. The purpose of this study is to propose a methodology to further improve the efficiency in hazelnut production by determining the most significant geographical criteria and using them for spatial queries and analysis in ArcGIS environment to detect most fertile hazelnut plantation areas. For the study, the Surmene district of Trabzon is selected for pilot region. A thematic map of hazelnut plantation areas created from the classification of WorldView-2 image of the district was used as the base map. Furthermore, a database is created with layers and cost maps using multicriteria decision methods. Detected most suitable areas for hazelnut production area are compared with the present situation. Proposed methodology and the database can be used by officials for better management of hazelnut production in Turkey, therefore in the world.

  13. Observational Constraints on Changing Arctic Methane Emissions

    NASA Astrophysics Data System (ADS)

    Dlugokencky, E. J.; Bruhwiler, L.; Lang, P. M.; Masarie, K.; Crotwell, A. M.; Crotwell, M.; Lowry, D.; Fisher, R. E.; Nisbet, E. G.

    2012-12-01

    Methane (CH4) is the second-most important greenhouse gas influenced by human activities. Its chemistry results in additional indirect climate effects from production of tropospheric O3, which also affects air quality, and stratospheric H2O. Because methane's atmospheric lifetime is relatively short (~9 yr) and ~70% of its emissions are anthropogenic, reductions in its emissions provide a potential cost-effective opportunity to slow the rate of increase of radiative forcing. Some fraction of decreased anthropogenic emissions may be canceled by potentially strong feed-backs to natural emissions. Because natural emissions of CH4 are diffuse, relatively weak, and highly-variable in space and time, quantifying changes for large spatial regions is difficult from small-scale field studies alone. Atmosphere observations at well-chosen sites integrate these emissions over large zonal regions and can be particularly useful for detecting changes in emissions. Paleo-climate studies indicate that CH4 emissions from Arctic wetlands are sensitive to climate and may provide a strong positive feedback as the Arctic warms. Measurements of atmospheric CH4 from the NOAA Global Monitoring Division's, Global Cooperative Air Sampling Network began in 1983. These high-precision observations offer key constraints on changes in Arctic CH4 emissions. During 2007, the CH4 growth rate increased in the Arctic, but was nearly zero during 2008. Use of the data in a chemical transport model suggest anomalous emissions of about 2 Tg CH4 during 2007, but returning to long-term average emissions after that. Another potential source affected by climate is emissions from methane clathrates. Measurements of methane's isotopic composition in the Arctic have been useful in showing that CH4 enhancements in Arctic air result from wetlands, not clathrates. Both potential sources are also constrained by spatial patterns in observed CH4, which indicate that, so far, changes in emissions of Arctic CH4 over the

  14. How does climate change influence Arctic mercury?

    PubMed

    Stern, Gary A; Macdonald, Robie W; Outridge, Peter M; Wilson, Simon; Chételat, John; Cole, Amanda; Hintelmann, Holger; Loseto, Lisa L; Steffen, Alexandra; Wang, Feiyue; Zdanowicz, Christian

    2012-01-01

    Recent studies have shown that climate change is already having significant impacts on many aspects of transport pathways, speciation and cycling of mercury within Arctic ecosystems. For example, the extensive loss of sea-ice in the Arctic Ocean and the concurrent shift from greater proportions of perennial to annual types have been shown to promote changes in primary productivity, shift foodweb structures, alter mercury methylation and demethylation rates, and influence mercury distribution and transport across the ocean-sea-ice-atmosphere interface (bottom-up processes). In addition, changes in animal social behavior associated with changing sea-ice regimes can affect dietary exposure to mercury (top-down processes). In this review, we address these and other possible ramifications of climate variability on mercury cycling, processes and exposure by applying recent literature to the following nine questions; 1) What impact has climate change had on Arctic physical characteristics and processes? 2) How do rising temperatures affect atmospheric mercury chemistry? 3) Will a decrease in sea-ice coverage have an impact on the amount of atmospheric mercury deposited to or emitted from the Arctic Ocean, and if so, how? 4) Does climate affect air-surface mercury flux, and riverine mercury fluxes, in Arctic freshwater and terrestrial systems, and if so, how? 5) How does climate change affect mercury methylation/demethylation in different compartments in the Arctic Ocean and freshwater systems? 6) How will climate change alter the structure and dynamics of freshwater food webs, and thereby affect the bioaccumulation of mercury? 7) How will climate change alter the structure and dynamics of marine food webs, and thereby affect the bioaccumulation of marine mercury? 8) What are the likely mercury emissions from melting glaciers and thawing permafrost under climate change scenarios? and 9) What can be learned from current mass balance inventories of mercury in the Arctic? The

  15. Determination of aspartame and its major decomposition products in foods.

    PubMed

    Prodolliet, J; Bruelhart, M

    1993-01-01

    A liquid chromatographic procedure already evaluated in a preceding study for the analysis of acesulfam-K is also suitable for the determination of the intense sweetener aspartame in tabletop sweetener, candy, fruit beverage, fruit pulp, soft drink, yogurt, cream, cheese, and chocolate preparations. The method also allows the determination of aspartame's major decomposition products: diketopiperazine, aspartyl-phenylalanine, and phenylalanine. Samples are extracted or diluted with water and filtered. Complex matrixes are centrifuged or clarified with Carrez solutions. An aliquot of the extract is analyzed on a reversed-phase muBondapak C18 column using 0.0125M KH2PO4 (pH 3.5)-acetonitrile ([85 + 15] or [98 + 2]) as mobile phase. Detection is performed by UV absorbance at 214 nm. Recoveries ranged from 96.1 to 105.0%. Decomposition of the sweetener was observed in most food samples. However, the total aspartame values (measured aspartame + breakdown products) were within -10% and +5% of the declared levels. The repeatabilities and the repeatability coefficients of variation were, respectively, 1.00 mg/100 g and 1.34% for products containing less than 45 mg/100 g aspartame and 4.11 mg/100 g and 0.91% for other products. The technique is precise and sensitive. It enables the detection of many food additives or natural constituents, such as other intense sweeteners, organic acids, and alkaloids, in the same run without interfering with aspartame or its decomposition products. The method is consequently suitable for quality control or monitoring. PMID:8471853

  16. Effect of CO2 enrichment on bacterial production and respiration and on bacterial carbon metabolism in Arctic waters

    NASA Astrophysics Data System (ADS)

    Motegi, C.; Tanaka, T.; Piontek, J.; Brussaard, C. P. D.; Gattuso, J. P.; Weinbauer, M. G.

    2012-10-01

    The impact of rising carbon dioxide (pCO2) on bacterial production (BP), bacterial respiration (BR) and bacterial carbon metabolism was investigated during the mesocosm experiment in Kongsfjord (Svalbard) in 2010. The mesocosm experiment lasted 30 days and nine mesocosms with pCO2 levels ranging from ca. 180 to 1400 μatm were used. Generally, BP gradually decreased in all mesocosms in an initial phase, showed a large (3.6-fold in average) but temporary increase on day 10, and increased slightly afterwards. BP increased with increasing pCO2 at the beginning of the experiment (day 5). This trend became inversed and BP decreased with increasing pCO2 on day 14 (after nutrient addition). Interestingly, increasing pCO2 enhanced the leucine and thymidine ratio at the end of experiment, suggesting that pCO2 may alter the growth balance of bacteria. In contrast to BP, no clear trend and effect of changes of pCO2 was observed for BR, bacterial carbon demand and bacterial growth efficiency. Our results suggest that (1) the response to elevated pCO2 had a strong temporal variation, potentially linked to the nutrient status, and (2) pCO2 had an influence on biomass accumulation (i.e. BP) rather than on the conversion of dissolved organic matter into CO2 (i.e. BR).

  17. Controls on the autochthonous production and respiration of organic matter in cryoconite holes on high Arctic glaciers

    NASA Astrophysics Data System (ADS)

    Telling, Jon; Anesio, Alexandre M.; Tranter, Martyn; Stibal, Marek; Hawkings, Jon; Irvine-Fynn, Tristram; Hodson, Andy; Butler, Catriona; Yallop, Marian; Wadham, Jemma

    2012-03-01

    There is current debate about whether the balance of photosynthesis and respiration has any impact on the net accumulation of organic matter on glacier surfaces. This study assesses controls on rates of net ecosystem production (NEP), respiration, and photosynthesis in cryoconite holes during the main melt season (June-August 2009) on three valley glaciers in Svalbard. Cryoconite thickness and organic matter content explained 87% of the total variation in rates of respiration (in units of volume), and organic matter (but not sediment depth) was a significant (p< 0.05) control on photosynthesis (by volume). The average rates of respiration and gross photosynthesis within the cryoconite holes were overall closely balanced, ranging from net autotrophic to heterotrophic. Sediment depth explained over half the variation of NEP, with net autotrophic rates typical only in sediment <3 mm thick. The measured rates of NEP were not sufficient to account for the organic matter which has likely accumulated in the cryoconite on timescales of less than decades, suggesting three alternatives for the source of the organic matter. First, the glacier surface may have received windblown allochthonous organic material from surrounding environments. Second, cryoconite may consist of in-washed autochthonous material from the glacier surface which has comparable organic carbon content. Third, much of the organic matter may have accumulated in the hole during a nascent period, when rates of NEP were much higher. The cycling of autochthonous labile carbon produced by phototrophs may sustain a significant proportion of the total in situ microbial activity within cryoconite holes.

  18. Processes Controlling Water Vapor in the Winter Arctic Stratospheric Middleworld

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Selkirk, Henry; Jensen, Eric; Sachse, Glenn; Podolske, James; Schoeberl, Mark; Browell, Edward; Ismail, Syed; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    Water vapor in the winter arctic stratospheric middleworld is import-an: for two reasons: (1) the arctic middleworld is a source of air for the upper Troposphere because of the generally downward motion, and thus its water vapor content helps determine upper tropospheric water, a critical part of the earth's radiation budget; and (2) under appropriate conditions, relative humidities will be large, even to the point of stratospheric cirrus cloud formation, leading to the production of active chlorine species that could destroy ozone. On a number of occasions during SOLVE, clouds were observed in the stratospheric middleworld by the DC-8 aircraft. These tended to coincide with regions of low temperatures, though some cases suggest water vapor enhancements due to troposphere-to-stratosphere transport. The goal of this work is to understand the importance of processes in and at the edge of the arctic stratospheric middleworld in determining water vapor at these levels. Specifically, is water vapor at these levels determined largely by the descent of air from above, or are clouds both within and at the edge of the stratospheric middleworld potentially important? How important is troposphere-to-stratosphere transport of air in determining stratospheric middleworld water vapor content? To this end, we will first examine the minimum saturation mixing ratios along theta/EPV tubes during the SOLVE winter and compare these with DC-8 water vapor observations. This will be a rough indicator of how high relative humidities can get, and the likelihood of cirrus cloud formation in various parts of the stratospheric middleworld. We will then examine saturation mixing ratios along both diabatic and adiabatic trajectories, comparing these values with actual aircraft water vapor observations, both in situ and remote. Finally, we will attempt to actually predict water vapor using minimum saturation mixing ratios along trajectories, cloud injection (derived from satellite imagery) along

  19. Determining the potential productivity of food crops in controlled environments

    NASA Technical Reports Server (NTRS)

    Bugbee, Bruce

    1992-01-01

    The quest to determine the maximum potential productivity of food crops is greatly benefitted by crop growth models. Many models have been developed to analyze and predict crop growth in the field, but it is difficult to predict biological responses to stress conditions. Crop growth models for the optimal environments of a Controlled Environment Life Support System (CELSS) can be highly predictive. This paper discusses the application of a crop growth model to CELSS; the model is used to evaluate factors limiting growth. The model separately evaluates the following four physiological processes: absorption of PPF by photosynthetic tissue, carbon fixation (photosynthesis), carbon use (respiration), and carbon partitioning (harvest index). These constituent processes determine potentially achievable productivity. An analysis of each process suggests that low harvest index is the factor most limiting to yield. PPF absorption by plant canopies and respiration efficiency are also of major importance. Research concerning productivity in a CELSS should emphasize: (1) the development of gas exchange techniques to continuously monitor plant growth rates and (2) environmental techniques to reduce plant height in communities.

  20. Arctic Amplification and Potential Mid-Latitude Weather Linkages

    NASA Astrophysics Data System (ADS)

    Overland, J. E.

    2014-12-01

    Increasing temperatures and other changes continued in the Arctic over the last decade, even though the rate of global warming has decreased in part due to a cool Pacific Ocean. Thus Arctic temperatures have increased at least 3 times the rate of mid-latitude temperatures. Credibility for persistent Arctic change comes from multiple indicators which are now available for multiple decades. Further, the spatial pattern of Arctic Amplification differs from patterns of natural variability. The role of the Arctic in the global climate system is based on multiple interacting feedbacks represented by these indicators as a causal basis for Arctic Amplification driven by modest global change. Many of these processes act on a regional basis and their non-linear interactions are not well captured by climate models. For example, future loss of sea ice due to increases in CO2 are demonstrated by these models but the rates of loss appear slow. It is reasonable to suspect that Arctic change which can produce the largest temperature anomalies on the planet and demonstrate recent extremes in the polar vortex could be linked to mid-latitude weather, especially as Arctic change will continue over the next decades. The meteorological community remains skeptical, however, in the sense of "not proven." Natural variability in chaotic atmospheric flow remains the main dynamic process, and it is difficult to determine whether Arctic forcing of a north-south linkage is emerging from the most recent period of Arctic change since 2007. Nonetheless, such a hypothesis is worthy of investigation, given the need to further understand Arctic dynamic atmospheric processes, and the potential for improving mid-latitude seasonal forecasts base on high-latitude forcing. Several AGU sessions and other forums over the next year (WWRP, IASC,CliC) address this issue, but the topic is not ready for a firm answer. The very level of controversy indicates the state of the science.

  1. Live from the Arctic

    NASA Astrophysics Data System (ADS)

    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

  2. NASA's Arctic Voyage 2010

    NASA Video Gallery

    NASA's first oceanographic research expedition left Alaska on June 15, 2010. The ICESCAPE mission will head into the Arctic to study sea ice and the changing ocean ecosystem. Listen to the scientis...

  3. 14C determination in different bio-based products

    NASA Astrophysics Data System (ADS)

    Santos Arévalo, Francisco-Javier; Gómez Martínez, Isabel; Agulló García, Lidia; Reina Maldonado, María-Teresa; García León, Manuel

    2015-10-01

    Radiocarbon determination can be used as a tool to investigate the presence of biological elements in different bio-based products, such as biodiesel blends. These products may also be produced from fossil materials obtaining the same final molecules, so that composition is chemically indistinguishable. The amount of radiocarbon in these products can reveal how much of these biological elements have been used, usually mixed with petrol derived components, free of 14C. Some of these products are liquid and thus the handling at the laboratory is not as straightforward as with solid samples. At Centro Nacional de Aceleradores (CNA) we have tested the viability of these samples using a graphitization system coupled to an elemental analyzer used for combustion of the samples, thus avoiding any vacuum process. Samples do not follow any chemical pre-treatment procedure and are directly graphitized. Specific equipment for liquid samples related to the elemental analyzer was tested. Measurement of samples was performed by low-energy AMS at the 1 MV HVEE facility at CNA, paying special attention to background limits and reproducibility during sample preparation.

  4. Development studies on determination of preservatives decomposition products.

    PubMed

    Zabrzewska, Beata; Chyła, Anna; Bogdan, Anna

    2014-01-01

    Preservatives are chemical substances whose role is to protect medicinal products against harmful changes caused by microorganisms. They are added to sterile medicinal products, such as eye drops and multidose solutions for injections, as well as to non-sterile products, such as water oral solutions, creams, gels, suppositories and capsules with liquid content. The most commonly used preservatives include: benzyl alcohol, butyl, ethyl, methyl and propyl p-hydroxybenzoates and their sodium salts. In medicinal products benzyl alcohol slowly oxidizes to benzaldehyde and benzoic acid while esters of p-hydroxybenzoic acid hydrolyze to p-hydroxybenzoic acid. HPLC methods were elaborated for identification and quantitative determination of the parabens, benzyl alcohol, active substances as well as their impurities in pharmaceuticals: oral solutions Amertil and Efforil (contain cetirizine hydrochloride or etilefrine hydrochloride and parabens), eye drops Difadol (contains diclofenac sodium and benzyl alcohol) and cream Tenasil (contains terbinafine hydrochloride and benzyl alcohol). The HPLC systems consisted of columns: Supelcosil LC-DP, Inertsil ODS-3 or Discovery HS F5 and three mobile phases mixtures of acetonitrile with buffers of various pH (3, 5 and 7) in proportions 45 : 55 (v/v). These systems have been characterized with appropriate selectivity (all the Rs values > 2) and sensitivity (LOD approx. 0.01 microg/mL). They also demonstrated satisfactory precision and a linear dependence between the analyte content and the peak area. PMID:25272883

  5. Arctic seabirds transport marine-derived contaminants.

    PubMed

    Blais, Jules M; Kimpe, Lynda E; McMahon, Dominique; Keatley, Bronwyn E; Mallory, Mark L; Douglas, Marianne S V; Smol, John P

    2005-07-15

    Long-range atmospheric transport of pollutants is generally assumed to be the main vector for arctic contamination, because local pollution sources are rare. We show that arctic seabirds, which occupy high trophic levels in marine food webs, are the dominant vectors for the transport of marine-derived contaminants to coastal ponds. The sediments of ponds most affected by seabirds had 60 times higher DDT, 25 times higher mercury, and 10 times higher hexachlorobenzene concentrations than nearby control sites. Bird guano greatly stimulates biological productivity in these extreme environments but also serves as a major source of industrial and agricultural pollutants in these remote ecosystems. PMID:16020729

  6. Simultaneous determination of chlorinated bacteriostats in cosmetic and pharmaceutical products.

    PubMed

    Wang, Lai-Hao; Tso, Mey; Chin, Chun-Yu

    2005-01-01

    A high-performance liquid chromatography method has been developed for simultaneous determination of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) and triclocarban (3,4,4'-trichlorocarbanilide) in cosmetic and pharmaceutical products. The two compounds could be separated on a Nucleosil C(18) column and eluted with acetonitrile and water (70:30, v/v) as the mobile phase and detected with a differential refractive index detector. The retention times of triclosan and triclocarban were 5.81 and 2.99 min, respectively. The results obtained were in good agreement with those obtained by a differential pulse voltammetric method. PMID:16116523

  7. Arctic Cities and Climate Change: A Geographic Impact Assessment

    NASA Astrophysics Data System (ADS)

    Shiklomanov, N. I.; Streletskiy, D. A.

    2014-12-01

    Arctic climate change is a concern for the engineering community, land-use planners and policy makers as it may have significant impacts on socio-economic development and human activities in the northern regions. A warmer climate has potential for a series of positive economic effects, such as development of maritime transportation, enhanced agricultural production and decrease in energy consumption. However, these potential benefits may be outwaited by negative impacts related to transportation accessibility and stability of existing infrastructure, especially in permafrost regions. Compared with the Arctic zones of other countries, the Russian Arctic is characterized by higher population, greater industrial development and urbanization. Arctic urban areas and associated industrial sites are the location of some of intense interaction between man and nature. However, while there is considerable research on various aspects of Arctic climate change impacts on human society, few address effects on Arctic cities and their related industries. This presentation overviews potential climate-change impacts on Russian urban environments in the Arctic and discusses methodology for addressing complex interactions between climatic, permafrost and socio-economic systems at the range of geographical scales. We also provide a geographic assessment of selected positive and negative climate change impacts affecting several diverse Russian Arctic cities.

  8. Arctic freshwater synthesis: Introduction

    NASA Astrophysics Data System (ADS)

    Prowse, T.; Bring, A.; Mârd, J.; Carmack, E.

    2015-11-01

    In response to a joint request from the World Climate Research Program's Climate and Cryosphere Project, the International Arctic Science Committee, and the Arctic Council's Arctic Monitoring and Assessment Program, an updated scientific assessment has been conducted of the Arctic Freshwater System (AFS), entitled the Arctic Freshwater Synthesis (AFSΣ). The major reason for joint request was an increasing concern that changes to the AFS have produced, and could produce even greater, changes to biogeophysical and socioeconomic systems of special importance to northern residents and also produce extra-Arctic climatic effects that will have global consequences. Hence, the key objective of the AFSΣ was to produce an updated, comprehensive, and integrated review of the structure and function of the entire AFS. The AFSΣ was organized around six key thematic areas: atmosphere, oceans, terrestrial hydrology, terrestrial ecology, resources and modeling, and the review of each coauthored by an international group of scientists and published as separate manuscripts in this special issue of Journal of Geophysical Research-Biogeosciences. This AFSΣ—Introduction reviews the motivations for, and foci of, previous studies of the AFS, discusses criteria used to define the domain of the AFS, and details key characteristics of the definition adopted for the AFSΣ.

  9. USGS Arctic science strategy

    USGS Publications Warehouse

    Shasby, Mark; Smith, Durelle

    2015-01-01

    The United States is one of eight Arctic nations responsible for the stewardship of a polar region undergoing dramatic environmental, social, and economic changes. Although warming and cooling cycles have occurred over millennia in the Arctic region, the current warming trend is unlike anything recorded previously and is affecting the region faster than any other place on Earth, bringing dramatic reductions in sea ice extent, altered weather, and thawing permafrost. Implications of these changes include rapid coastal erosion threatening villages and critical infrastructure, potentially significant effects on subsistence activities and cultural resources, changes to wildlife habitat, increased greenhouse-gas emissions from thawing permafrost, threat of invasive species, and opening of the Arctic Ocean to oil and gas exploration and increased shipping. The Arctic science portfolio of the U.S. Geological Survey (USGS) and its response to climate-related changes focuses on landscapescale ecosystem and natural resource issues and provides scientific underpinning for understanding the physical processes that shape the Arctic. The science conducted by the USGS informs the Nation's resource management policies and improves the stewardship of the Arctic Region.

  10. Synthesizing Bathymetry Data within a Community Dependent Basemap for Spatial Data Display in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Raines, C.; Wright, D. J.

    2014-12-01

    The Esri Ocean Basemap program, an extension of the Esri Community Maps program, grows and develops based on the participation of the scientific and GIS communities. Not only does the Ocean Basemap evolve from the authoritative data contributions, but user needs influence the direction of the program as well. With the eyes of the scientific and maritime community shifting northerly to the Arctic, it became obvious that both the scientific and GIS communities needed a more appropriate basemap to best accommodate and share their work. The Esri Ocean Basemap team began designing a new Ocean Basemap product to support work conducted in the Arctic Ocean. The team first complied the best available data sources and applicable community contributions. By leveraging commercial-off-the-shelf capabilities in the ArcGIS platform, the team converted datasets from a range of governmental, non-governmental and private entities into compatible formats and ensured a uniform data projection for all of the datasets. In addition, the team developed and applied automatic sorting rules to create a surface model for cartographic purposes using the ArcGIS for Maritime: Bathymetry solution. After determining a tiling scheme, the Ocean Basemap team officially published the Arctic Ocean Basemap. The Arctic Ocean Basemap provides the scientific and GIS communities with a WMTS-enabled, appropriately projected basemap to support their maps and applications.

  11. Recent, unprecedented, arctic ozone losses: climate change or large interannual variability?

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Polvani, L. M.

    2012-04-01

    The record ozone loss over the Arctic in the spring of 2011 [e.g., Manney et al., 2011] highlights the importance of a detailed understanding of the connection between cold polar temperatures, polar stratospheric clouds (PSCs) and column ozone. Several studies have analyzed the empirical relationship between PSC volume (Vpsc) and ozone loss in the Arctic [e.g., Rex et al., 2006], and put forward the hypothesis that the coldest Arctic winters are getting colder and therefore anomalous ozone losses in the Arctic are likely to increase in the coming decades. In the present study we analyze trends and variability in polar temperatures, Vpsc and column ozone, using both reanalysis products (ERA40, MERRA) and numerical model output (from selected models participating in the Chemistry-Climate Model Validation Activity). Beyond considering mean values, we employ a variety of statistical measures for extremes (i.e., high quantiles) in order to identify possible changes in the frequency distribution of polar temperatures and Vpsc, and attempt to determine whether the recent occurrences of record ozone loss are indicative of statistically significant trends or simply a reflection of large natural variability.

  12. Determination of Key Hydrocarbon Autoxidation Products by Fluorescence.

    PubMed

    Shah, Ron; Pratt, Derek A

    2016-08-01

    Hydroperoxides and carboxylic acids are key primary products that arise in the autoxidation of hydrocarbons. We have developed a simple approach to rapidly and simultaneously determine both types of products using hydroperoxide- and acid-sensitive moieties conjugated to nonpolar coumarin- and BODIPY-based fluorophores. The coumarin- and BODIPY-conjugated amine probes described here undergo 38- and 8-fold enhancement, respectively, upon protonation in a solvent system compatible with heavy hydrocarbons. The latter can be used directly with our previously described hydroperoxide-sensitive coumarin-conjugated phosphine probe to enable rapid quantification of both carboxylic acids and hydroperoxides in hydrocarbon samples. The utility of the approach is illustrated by the ready determination of the differing relative rates of hydroperoxide and acid formation with changes in hydrocarbon structure (e.g., n-hexadecane vs 1-hexadecene vs a lubricant base stock). The method offers significant versatility and automation compared with common but laborious titration approaches, and greatly improves screening efficiency and accuracy for the identification of novel radical-trapping antioxidants for high temperature applications. This application was demonstrated by the automated analysis of hydroperoxides and carboxylic acids (by microplate reader) in samples from 24 inhibited autoxidations of a lubricating oil, which were carried out on a parallel synthesizer at 160 °C in triplicate in a single day. PMID:27384266

  13. The Arctic Visiting Speakers Program

    NASA Astrophysics Data System (ADS)

    Wiggins, H. V.; Fahnestock, J.

    2013-12-01

    The Arctic Visiting Speakers Program (AVS) is a program of the Arctic Research Consortium of the U.S. (ARCUS) and funded by the National Science Foundation. AVS provides small grants to researchers and other Arctic experts to travel and share their knowledge in communities where they might not otherwise connect. The program aims to: initiate and encourage arctic science education in communities with little exposure to arctic research; increase collaboration among the arctic research community; nurture communication between arctic researchers and community residents; and foster arctic science education at the local level. Individuals, community organizations, and academic organizations can apply to host a speaker. Speakers cover a wide range of arctic topics and can address a variety of audiences including K-12 students, graduate and undergraduate students, and the general public. Preference is given to tours that reach broad and varied audiences, especially those targeted to underserved populations. Between October 2000 and July 2013, AVS supported 114 tours spanning 9 different countries, including tours in 23 U.S. states. Tours over the past three and a half years have connected Arctic experts with over 6,600 audience members. Post-tour evaluations show that AVS consistently rates high for broadening interest and understanding of arctic issues. AVS provides a case study for how face-to-face interactions between arctic scientists and general audiences can produce high-impact results. Further information can be found at: http://www.arcus.org/arctic-visiting-speakers.

  14. The future of Arctic benthos: Expansion, invasion, and biodiversity

    NASA Astrophysics Data System (ADS)

    Renaud, Paul E.; Sejr, Mikael K.; Bluhm, Bodil A.; Sirenko, Boris; Ellingsen, Ingrid H.

    2015-12-01

    One of the logical predictions for a future Arctic characterized by warmer waters and reduced sea-ice is that new taxa will expand or invade Arctic seafloor habitats. Specific predictions regarding where this will occur and which taxa are most likely to become established or excluded are lacking, however. We synthesize recent studies and conduct new analyses in the context of climate forecasts and a paleontological perspective to make concrete predictions as to relevant mechanisms, regions, and functional traits contributing to future biodiversity changes. Historically, a warmer Arctic is more readily invaded or transited by boreal taxa than it is during cold periods. Oceanography of an ice-free Arctic Ocean, combined with life-history traits of invading taxa and availability of suitable habitat, determine expansion success. It is difficult to generalize as to which taxonomic groups or locations are likely to experience expansion, however, since species-specific, and perhaps population-specific autecologies, will determine success or failure. Several examples of expansion into the Arctic have been noted, and along with the results from the relatively few Arctic biological time-series suggest inflow shelves (Barents and Chukchi Seas), as well as West Greenland and the western Kara Sea, are most likely locations for expansion. Apparent temperature thresholds were identified for characteristic Arctic and boreal benthic fauna suggesting strong potential for range constrictions of Arctic, and expansions of boreal, fauna in the near future. Increasing human activities in the region could speed introductions of boreal fauna and reduce the value of a planktonic dispersal stage. Finally, shelf regions are likely to experience a greater impact, and also one with greater potential consequences, than the deep Arctic basin. Future research strategies should focus on monitoring as well as compiling basic physiological and life-history information of Arctic and boreal taxa, and

  15. What are the patterns of carbon allocation in Arctic shrub tundra: do species differ?

    NASA Astrophysics Data System (ADS)

    Street, Lorna; Subke, Jens-Arne; Baxter, Robert; Billett, Mike; Dinsmore, Kerry; Lessels, Jason; Wookey, Philip

    2014-05-01

    Arctic "greening" is now a well-accepted phenomenon; multiple lines of evidence suggest that plant productivity has increased, driven by increases in shrub abundance. There is very little understanding, however, of how this "shrubification" will impact biogeochemical cycling, including the allocation and turnover of carbon. Recent research has shown, for example, that greater plant productivity is not necessary associated with greater ecosystem C storage. Proliferation of a number of shrub species has been observed in different regions; for example increased willow growth in Arctic Russia, as opposed to primarily alder expansion in NW Canada, where stem density increased 68 % between 1968 and 2004. The degree to which shrub type will determine the impacts of shrub expansion on the carbon cycle is unknown. We use 13C pulse-labelling to trace the fate of recently photosynthesised carbon in vegetation dominated by two common Arctic shrubs, Betula nana (dwarf birch) and Alnus viridis (green alder) just above the Arctic treeline in NW Canada. We quantify the amount of 13C assimilated, and the proportion of assimilate returned to the atmosphere via respiration versus that allocated to plant tissues. This enables an analysis of the contrasting carbon-use-efficiencies and aboveground versus belowground allocation patterns in the two vegetation types. We use these novel field data to address the hypothesis that belowground C allocation in A. viridis (a symbiotic nitrogen fixing species) is a smaller proportion of total C assimilation, as this species supports less extensive ectomycorrhizal networks compared to B. nana. This is the first tracer study of carbon allocation in N-fixing and non-N-fixing vegetation types in a natural system and provides crucial data for predictive modelling of the Arctic carbon cycle.

  16. Qualitative determination of carbon black in food products.

    PubMed

    Miranda-Bermudez, E; Belai, N; Harp, B Petigara; Yakes, B J; Barrows, J N

    2012-01-01

    Carbon black (C.I. 77266) is an insoluble pigment produced by the partial combustion of hydrocarbons. The pigment is known by several synonyms, including vegetable carbon, lamp black and carbon ash, that correspond to the raw materials and methods used for its production. Vegetable carbon (E153) is permitted for use in colouring food in the European Union. The US Food and Drug Administration (USFDA) has not approved the use of any type of carbon black for colouring food, although the agency batch certifies the pigment as D&C Black No. 2 for use in colouring certain cosmetics. Since carbon black (as vegetable carbon) may be present in food products offered for import into the United States, the USFDA's district laboratories need a qualitative analytical method for determining its presence. We have developed an extraction method for this purpose. A sample is broken down and dissolved with nitric acid. The resulting solution is filtered and treated with hydrochloric acid to dissolve any black iron oxide also present as a colour additive. A black residue remaining on the filter paper indicates the presence of carbon black in the food. We confirmed the presence of carbon black in residues from several standards and food products using Raman spectroscopy. The limit of detection for this method is 0.0001%. PMID:22035229

  17. The contiguous domains of Arctic Ocean advection: Trails of life and death

    NASA Astrophysics Data System (ADS)

    Wassmann, P.; Kosobokova, K. N.; Slagstad, D.; Drinkwater, K. F.; Hopcroft, R. R.; Moore, S. E.; Ellingsen, I.; Nelson, R. J.; Carmack, E.; Popova, E.; Berge, J.

    2015-12-01

    The central Arctic Ocean is not isolated, but tightly connected to the northern Pacific and Atlantic Oceans. Advection of nutrient-, detritus- and plankton-rich waters into the Arctic Ocean forms lengthy contiguous domains that connect subarctic with the arctic biota, supporting both primary production and higher trophic level consumers. In turn, the Arctic influences the physical, chemical and biological oceanography of adjacent subarctic waters through southward fluxes. However, exports of biomass out of the Arctic Ocean into both the Pacific and Atlantic Oceans are thought to be far smaller than the northward influx. Thus, Arctic Ocean ecosystems are net biomass beneficiaries through advection. The biotic impact of Atlantic- and Pacific-origin taxa in arctic waters depends on the total supply of allochthonously-produced biomass, their ability to survive as adults and their (unsuccessful) reproduction in the new environment. Thus, advective transport can be thought of as trails of life and death in the Arctic Ocean. Through direct and indirect (mammal stomachs, models) observations this overview presents information about the advection and fate of zooplankton in the Arctic Ocean, now and in the future. The main zooplankton organisms subjected to advection into and inside the Arctic Ocean are (a) oceanic expatriates of boreal Atlantic and Pacific origin, (b) oceanic Arctic residents and (c) neritic Arctic expatriates. As compared to the Pacific gateway the advective supply of zooplankton biomass through the Atlantic gateways is 2-3 times higher. Advection characterises how the main planktonic organisms interact along the contiguous domains and shows how the subarctic production regimes fuel life in the Arctic Ocean. The main differences in the advective regimes through the Pacific and Atlantic gateways are presented. The Arctic Ocean is, at least in some regions, a net heterotrophic ocean that - during the foreseeable global warming trend - will more and more rely

  18. Arctic summary report: Outer Continental Shelf oil and gas activities in the Arctic and their onshore impacts

    NASA Astrophysics Data System (ADS)

    Lynch, C.; Slitor, D. L.; Rudolph, R. W.

    1985-01-01

    Issues and developments occuring in the Arctic Outer Continental Shelf subregion are discussed. The geology and hydrocarbon potential of the Diapir Field petroleum provinces are detailed. Recent lease sales, exploration activities, and the first development proposals for offshore areas of the North slope are considered. Issues relating to transporting resources from production islands to shore and various proposals for moving Arctic hydrocarbons to market are presented. Production projects onshore and possible support bases for offshore activity are also examined.

  19. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Crane, R. G.

    1985-01-01

    A daily climatology of the atmospheric circulation of the Arctic and the associated cloud conditions were determined. These are used for comparisons with the variability of general circulation model, generated circulation, and cloud cover for the same region.

  20. Evaluation of the Arctic Surface Radiation Budget in CMIP5 Models

    NASA Astrophysics Data System (ADS)

    Boeke, R.; Taylor, P. C.

    2015-12-01

    The Arctic region is warming at a rate nearly double the global average, and this trend is predicted to continue for the coming decades, as simulated in the Coupled Model Intercomparison Project 5 (CMIP5) climate projections. Despite the consistency in the projected surface warming rate relative to the globe, significant inter-model spread is found in the overall magnitude of Arctic surface temperature change, which leads to large inter-model spread in the simulation of surface radiative properties. The goal of this presentation is to determine the biases in the representation of the Arctic surface radiation budget seasonal cycle and discover the physical processes that explain the significant spread in projected Arctic warming. First, biases in the simulated Arctic surface radiation budget seasonal cycle within several CMIP5 climate models participating in the Historical forcing scenario are evaluated with respect to the CERES-SFC-EBAF and C3M data products. Next, the equations for longwave and shortwave cloud radiative forcing are decomposed using an independent column approximation (ICA) to identify which factors are driving changes to the annual cycle of cloud radiative forcing as well as what terms are contributing to the inter-model spread in the simulation of the surface energy budget. A multiple linear regression methodology is applied to the results of the ICA analysis using four atmospheric state variables as predictors: surface pressure, lower tropospheric stability, sea-ice concentration, and surface temperature. The impact of thermodynamics, atmospheric dynamics, and cloud-sea ice interactions on the annual cycle of cloud radiative effect will be determined.

  1. Impacts of Organic Macromolecules, Chlorophyll and Soot on Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Flanner, M.; Dubey, M. K.

    2014-12-01

    Recent intensification of Arctic amplification can be strongly connected to positive feedback relating black carbon deposition to sea ice surface albedo. In addition to soot deposition on the ice and snow pack, ice algal chlorophyll is likely to compete as an absorber and redistributor of energy. Hence, solar radiation absorption by chlorophyll and some components of organic macromolecules in/under the ice column is currently being examined to determine the level of influence on predicted rate of ice loss. High amounts of organic macromolecules and chlorophyll are produced in global sea ice by the bottom microbial community and also in vertically distributed layers where substantial biological activities take place. Brine channeling in columnar ice can allow for upward flow of nutrients which leads to greater primary production in the presence of moderate light. Modeling of the sea-ice processes in tandem with experiments and field observations promises rapid progress in enhancing Arctic ice predictions. We are designing and conducting global climate model experiments to determine the impact of organic macromolecules and chlorophyll on Arctic sea ice. Influences on brine network permeability and radiation/albedo will be considered in this exercise. Absorption by anthropogenic materials such as soot and black carbon will be compared with that of natural pigments. We will indicate areas of soot and biological absorption dominance in the sense of single scattering, then couple into a full radiation transfer scheme to attribute the various contributions to polar climate change amplification. The work prepares us to study more traditional issues such as chlorophyll warming of the pack periphery and chemical effects of the flow of organics from ice internal communities. The experiments started in the Arctic will broaden to include Antarctic sea ice and shelves. Results from the Arctic simulations will be presented.

  2. Arctic Sea Ice Maximum 2011

    NASA Video Gallery

    AMSR-E Arctic Sea Ice: September 2010 to March 2011: Scientists tracking the annual maximum extent of Arctic sea ice said that 2011 was among the lowest ice extents measured since satellites began ...

  3. Arctic Rabies – A Review

    PubMed Central

    Mørk, Torill; Prestrud, Pål

    2004-01-01

    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. PMID:15535081

  4. Beyond Thin Ice: Co-Communicating the Many Arctics

    NASA Astrophysics Data System (ADS)

    Druckenmiller, M. L.; Francis, J. A.; Huntington, H.

    2015-12-01

    Science communication, typically defined as informing non-expert communities of societally relevant science, is persuaded by the magnitude and pace of scientific discoveries, as well as the urgency of societal issues wherein science may inform decisions. Perhaps nowhere is the connection between these facets stronger than in the marine and coastal Arctic where environmental change is driving advancements in our understanding of natural and socio-ecological systems while paving the way for a new assortment of arctic stakeholders, who generally lack adequate operational knowledge. As such, the Arctic provides opportunity to advance the role of science communication into a collaborative process of engagement and co-communication. To date, the communication of arctic change falls within four primary genres, each with particular audiences in mind. The New Arctic communicates an arctic of new stakeholders scampering to take advantage of unprecedented access. The Global Arctic conveys the Arctic's importance to the rest of the world, primarily as a regulator of lower-latitude climate and weather. The Intra-connected Arctic emphasizes the increasing awareness of the interplay between system components, such as between sea ice loss and marine food webs. The Transforming Arctic communicates the region's trajectory relative to the historical Arctic, acknowledging the impacts on indigenous peoples. The broad societal consensus on climate change in the Arctic as compared to other regions in the world underscores the opportunity for co-communication. Seizing this opportunity requires the science community's engagement with stakeholders and indigenous peoples to construct environmental change narratives that are meaningful to climate responses relative to non-ecological priorities (e.g., infrastructure, food availability, employment, or language). Co-communication fosters opportunities for new methods of and audiences for communication, the co-production of new interdisciplinary

  5. Synthesizing International Understanding of Changes in the Arctic Hydrological System

    NASA Astrophysics Data System (ADS)

    Pundsack, J. W.; Vorosmarty, C. J.; Hinzman, L. D.

    2009-12-01

    internationally). The workshop brought together approximately 40 participants, with roughly equal numbers from North America and Europe/Scandinavia, and included representatives from Canada, Russia, Germany, Iceland, Sweden, Norway, Finland, Denmark/Greenland, and the US. This talk will focus on findings of the workshop, highlighting advances in Arctic research that have taken flight over the last decade, specifically stimulated by considering the hydrologic cycle as an integrating force and fundamental building block uniting atmospheric, oceanic, cryospheric and terrestrial domains of the pan-Arctic system. The authors will present a future vision for systems-level science of Arctic hydrology and affiliated energy and carbon cycles. A scientific roadmap will be introduced, outlining the main research priorities, robust global and regional geo-information data products, improved models and effective data assimilation systems to forward the science of water in the Arctic.

  6. Determining the optimal product-mix using integer programming: An application in audio speaker production

    NASA Astrophysics Data System (ADS)

    Khan, Sahubar Ali Bin Mohamed Nadhar; Ahmarofi, Ahmad Afif Bin

    2014-12-01

    In manufacturing sector, production planning or scheduling is the most important managerial task in order to achieve profit maximization and cost minimization. With limited resources, the management has to satisfy customer demand and at the same time fulfill company's objective, which is to maximize profit or minimize cost. Hence, planning becomes a significant task for production site in order to determine optimal number of units for each product to be produced. In this study, integer programming technique is used to develop an appropriate product-mix planning to obtain the optimal number of audio speaker products that should be produced in order to maximize profit. Branch-and-bound method is applied to obtain exact integer solutions when non-integer solutions occurred. Three major resource constraints are considered in this problem: raw materials constraint, demand constraint and standard production time constraint. It is found that, the developed integer programming model gives significant increase in profit compared to the existing method used by the company. At the end of the study, sensitivity analysis was performed to evaluate the effects of changes in objective function coefficient and available resources on the developed model. This will enable the management to foresee the effects on the results when some changes happen to the profit of its products or available resources.

  7. Atmospheric heat transfer to the Arctic under main synoptic processes

    NASA Astrophysics Data System (ADS)

    Yurova, Alla; Gnatiuk, Natalia; Bobylev, Leonid; Zhu, Yali

    2016-04-01

    Arctic - mid-latitude teleconnections are operating in both ways and behind them are potentially some causes of the enhanced Arctic warming (e.g., through heat transfer from lower to higher latitudes) and the feedbacks from the Arctic climate to the mid-latitude weather patterns. In order to explain the variability of the surface air temperature in the Arctic, we aim to analyse the typical synoptic situations that, we hypothesize, are characterized by a specific patterns of heat exchange between the Arctic and mid-latitudes. According to classification of synoptic processes in the Arctic developed at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg major typical groups of synoptic situations in the Arctic are few (six). They correspond to position and intensity of low- and high-pressure centres. Therefore, the whole data sample for the winter period for the entire period of instrumental observations (archive exists back to 1939) can be split into six groups that sub-sample each of six groups/types of synoptic situations. Then heat transfer to the Arctic can be estimated as the divergence of the horizontal (advective) heat flux (the product of wind speed and temperature gradient) within each vertical atmospheric layer, which is calculated based on the ERA Interim Reanalysis data for the winter season (1979-now). Mapping heat divergence fields will reveal the main mid-latitude sources of heat transported to the Arctic, average for the whole data sample and for each of the six main groups of synoptic situations. This work was supported by RFBR grants 16-55-53031

  8. Determination of advanced glycation endproducts in cooked meat products.

    PubMed

    Chen, Gengjun; Smith, J Scott

    2015-02-01

    Advanced glycation endproducts (AGEs), a pathogenic factor implicated in diabetes and other chronic diseases, are produced in cooked meat products. The objective of this study was to determine the AGE content, as measured by Nε-carboxymethyllysine (CML) levels, in cooked chicken, pork, beef and fish (salmon and tilapia) prepared by three common cooking methods used by U.S. consumers: frying, baking, and broiling. The CML was detected in all the cooked samples, but the levels were dependent on types of meat, cooking conditions, and the final internal temperature. Broiling and frying at higher cooking temperature produced higher levels of CML, and broiled beef contained the highest CML content (21.8μg/g). Baked salmon (8.6μg/g) and baked tilapia (9.7μg/g) contained less CML as compared to the other muscle food samples. PMID:25172699

  9. [Quantitative determination of some thickeners in dairy products (author's transl)].

    PubMed

    Glück, U; Thier, H P

    1980-04-01

    An analytical method is described, by which nine polysaccharides used as thickeners for dairy products (locust bean gum, guar, gum arabic, tragacanth, arabinogalactan, carrageenan, furcellaran, agar, xanthan) can be identified in foods relatively rapidly and at the same time determined quantitatively. In this procedure interfering substances like fat, starch, proteins, sugars and salts are removed, the isolated polysaccharides are hydrolysed by trifluoroacetic acid and the monosaccharides resulting are measured by g.l.c. as aldonitrileacetates. The quantitative evaluation of the gas chromatograms is made by means of an internal standard and the content of thickener in the sample is calculated from one of the sugars. Recoveries of 80--90% with relative standard deviations of 5--10% were obtained when adding 0,05% of the thickeners to skim milk or 1--2% to mixtures of ice cream or pudding constituents. PMID:7395389

  10. Determination of egg proteins in food products by enzyme immunoassay.

    PubMed

    Yeung, J M; Newsome, W H; Abbott, M A

    2000-01-01

    An enzyme-linked immunosorbent assay (ELISA) was developed to determine the presence of egg proteins in foods. The polyclonal antibodies developed were specific to whole egg proteins and did not cross-react with any of the 38 nuts, legumes, or other common food ingredients tested. The concentrations of egg proteins that will inhibit 50% of antibody-antigen binding, IC50, were 3-7 ng/mL, and the linear range was 0.5-62.5 ng/mL. The detection limit was 0.2 ppm for various foods. Recoveries ranged from 67 to 96%. The intra- and inter-assay coefficients of variation in this procedure were 10-13% for ice cream spiked at 0.8 and 1.6 ppm. The ELISA has been applied to ice creams, noodles, pasta, and breads. Egg proteins were identified in all declared egg products, and no false positives were found. PMID:10693015

  11. Structure Determination of Natural Products by Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Du.

    High-field NMR experiments were used to determine the full structures of six new natural products extracted from plants. These are: four saponins (PT-2, P1, P2 and P3) from the plant Alphitonia zizyphoides found in Samoa; one sesquiterpene (DF-4) from Douglas fir and one diterpene derivative (E-2) from a Chinese medicinal herb. By concerted use of various 1D and 2D NMR techniques, the structures of the above compounds were established and complete resonance assignments were achieved. The 2D INADEQUATE technique coupled with a computerized spectral analysis was extensively used. When carried out on concentrations as low as 60 mg of sample, this technique provided absolute confirmation of the assignments for 35 of the possible 53 C-C bonds for PT-2. On 30 mg of sample of E-21, it revealed 22 of 28 possible C-C bonds.

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

    NASA Astrophysics Data System (ADS)

    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

  13. FIRE Arctic Clouds Experiment

    NASA Technical Reports Server (NTRS)

    Curry, J. A.; Hobbs, P. V.; King, M. D.; Randall, D. A.; Minnis, P.; Issac, G. A.; Pinto, J. O.; Uttal, T.; Bucholtz, A.; Cripe, D. G.; Gerber, H.; Fairall, C. W.; Garrett, T. J.; Hudson, J.; Intrieri, J. M.; Jakob, C.; Jensen, T.; Lawson, P.; Marcotte, D.; Nguyen, L.

    1998-01-01

    An overview is given of the First ISCCP Regional Experiment (FIRE) Arctic Clouds Experiment that was conducted in the Arctic during April through July, 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary layer clouds. The observations will be used to evaluate and improve climate model parameterizations of cloud and radiation processes, satellite remote sensing of cloud and surface characteristics, and understanding of cloud-radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and Barrow, Alaska. In this paper we describe the programmatic and science objectives of the project, the experimental design (including research platforms and instrumentation), conditions that were encountered during the field experiment, and some highlights of preliminary observations, modelling, and satellite remote sensing studies.

  14. Determining host suitability of pecan for stored-product insects.

    PubMed

    Shufran, A A; Mulder, P G; Payton, M E; Shufran, K A

    2013-04-01

    A no-choice test was performed to determine survival and reproductive capacity of stored-product insect pests on pecan, Carya illinoensis (Wangenheim) Koch. Insects used were Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae); sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Cucujidae); red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae); lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae); and rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae). Fifty adults of each beetle species or 10 reproductive pairs of P. interpunctella adults were placed in 0.5-liter containers with either whole-shell pecans, cracked-shell pecans, randomly selected in-shell pecans, pecan nutmeats, cracked wheat, or glass beads and held at 28 degrees C, 60-70% relative humidity, and 16:8 (L:D) photoperiod for 2, 4, 6, and 8 wk. Four replications of each insect-diet-interval combination were performed. Larvae of P. interpunctella, O. surinamensis, T. castaneum, C. ferrugineus, and adult P. interpunctella and O. surinamensis developed on cracked and nutmeat pecan diets. R. dominica did not complete reproduction on pecans. Knowledge that these pests can reproduce on stored pecan will assist pecan growers, accumulators, and storage facilities in preventing insect outbreaks on their product. PMID:23786103

  15. Bioaccumulation of radiocaesium in Arctic seals.

    PubMed

    Carroll, Jolynn; Wolkers, Hans; Andersen, Magnus; Rissanen, Kristina

    2002-12-01

    Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82 degrees N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23 +/- 0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (approximately 0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed. PMID:12523541

  16. NIR reflectance method to determine moisture content in food products

    NASA Astrophysics Data System (ADS)

    Kandala, C. V. K.; Konda Naganathan, G.; Subbiah, J.

    2008-08-01

    Moisture content (MC) is an important quality factor that is measured and monitored, at various stages of processing and storage, in the food industry. There are some commercial instruments available that use near infrared (NIR) radiation measurements to determine the moisture content of a variety of grain products, such as wheat and corn, with out the need of any sample grinding or preparation. However, to measure the MC of peanuts with these instruments the peanut kernels have to be chopped into smaller pieces and filled into the measuring cell. This is cumbersome, time consuming and destructive. An NIR reflectance method is presented here by which the average MC of about 100 g of whole kernels could be determined rapidly and nondestructively. The MC range of the peanut kernels tested was between 8% and 26%. Initially, NIR reflectance measurements were made at 1 nm intervals in the wave length range of 1000 nm to 1800 nm and the data was modeled using partial least squares regression (PLSR). The predicted values of the samples tested in the above range were compared with the values determined by the standard air-oven method. The predicted values agreed well with the air-oven values with an R2 value of 0.96 and a standard error of prediction (SEP) of 0.83. Using the PLSR beta coefficients, five key wavelengths were identified and using multiple linear regression (MLR) method MC predictions were made. The R2 and SEP values of the MLR model were 0.84 and 1.62, respectively. Both methods performed satisfactorily and being rapid, nondestructive, and non-contact, may be suitable for continuous monitoring of MC of grain and peanuts as they move on conveyor belts during their processing.

  17. DETERMINATION OF AZOXYSTROBIN AND DIFENOCONAZOLE IN PESTICIDE PRODUCTS.

    PubMed

    Lazić, S; Šunjka, D

    2015-01-01

    In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of azoxystrobin and difenoconazole in suspension concentrate pesticide formulations, with the aim of the product quality control. Azoxystrobin, strobilurin fungicide and difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether), triazole fungicide, are used for the protection of plants from wide spectrum of fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for azoxystrobin and difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for azoxystrobin and 0.5% for difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for azoxystrobin and difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for azoxystrobin and 103.2% for difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination

  18. Concentration maxima of volatile organic iodine compounds in the bottom layer water and the cold, dense water over the Chukchi Sea in the western Arctic Ocean: a possibility of production related to the degradation of organic matter

    NASA Astrophysics Data System (ADS)

    Ooki, A.; Kawasaki, S.; Kuma, K.; Nishino, S.; Kikuchi, T.

    2016-01-01

    We conducted a shipboard observation over the Chukchi Sea and the Canada Basin in the western Arctic Ocean in September and October 2012 to obtain vertical distributions of four volatile organic iodine compounds (VOIs) in seawater. The VOIs observed in this study were iodomethane (CH3I), iodoethane (C2H5I), diiodomethane (CH2I2), and chloroiodomethane (CH2ClI). Maximum concentrations of the four VOIs were found in the bottom layer water over the Chukchi Sea shelf, in which layer the maximum concentration of ammonium (NH4+) also occurred. A significant correlation was observed between C2H5I and NH4+ (correlation coefficient R = 0.93, P < 0.01, n = 64) and between CH3I and NH4+ (R= 0.77, P < 0.01, n = 64), suggesting that the production of these VOIs increased with the degradation of organic matter. Over the northern Chukchi Sea shelf-slope area, concentration maxima of CHI2, CH2ClI, and CH3I were found in the subsurface cold, dense water (CDW). A large nitrogen deficit (N deficit = NH4++ NO3-+ NO2--16PO43-) occurred simultaneously in this water, suggesting the production of the three VOIs in the sediment or the bottom layer water over the shelf, probably in association with the degradation of organic matter. We conclude that VOI production over the Chukchi Sea shelf can be largely attributed to the degradation of organic matter that is produced in the highly productive shelf water. High concentrations of CH2ClI were also found in the Alaskan Coastal Water (ACW) from the Bering Strait to the surface of the northern Chukchi slope. The VOIs that originated at the Chukchi Sea shelf are expected to be laterally transported to the Arctic Ocean basin through the CDW and the surface ACW.

  19. Concentration maxima of volatile organic iodine compounds in the bottom layer water and the cold, dense water over the Chukchi Sea in the western Arctic Ocean: a possibility of production related to degradation of organic matter

    NASA Astrophysics Data System (ADS)

    Ooki, A.; Kawasaki, S.; Kuma, K.; Nishino, S.; Kikuchi, T.

    2015-07-01

    We conducted a shipboard observation over the Chukchi Sea and the Canada Basin in the western Arctic Ocean in September and October 2012 to obtain vertical distributions of four volatile organic iodine compounds (VOIs) in seawater. VOIs are believed to play a role in ozone destruction in the troposphere and lower stratosphere. The VOIs observed in this study were iodomethane (CH3I), iodoethane (C2H5I), diiodomethane (CH2I2) and chloroiodomethane (CH2ClI). Maximum concentrations of the four VOIs were found in the bottom layer water over the Chukchi Sea shelf, in which layer the maximum concentration of ammonium (NH4+) also occurred. A significant correlation was observed between C2H5I and NH4+ (correlate coefficient R = 0.93) and between CH3I and NH4+ (R = 0.77), suggesting production of these VOIs increased with degradation of organic matter. Over the northern Chukchi Sea shelf-slope area, concentration maxima of CH2I2, CH2ClI, and CH3I were found in the subsurface cold, dense water (CDW). A large nitrogen deficit (N-deficit = NH4+ + NO3- + NO2- - 16PO43-) simultaneously occurred in this water, suggesting production of the three VOIs in the sediment or the bottom layer water over the shelf, probably in association with degradation of organic matter. We conclude that VOI production over the Chukchi Sea shelf can be largely attributed to the degradation of organic matter that is produced in the highly productive shelf water. High concentrations of CH2ClI were also found in the Alaskan Coastal Water (ACW) from the Bering Strait to the surface of the northern Chukchi slope. The VOIs that originated at the Chukchi Sea shelf are expected to be laterally transported to the Arctic Ocean Basin though the subsurface CDW and the surface ACW.

  20. Late Cretaceous seasonal ocean variability from the Arctic.

    PubMed

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

    2009-07-01

    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. PMID:19587768

  1. Export of algal biomass from the melting Arctic sea ice.

    PubMed

    Boetius, Antje; Albrecht, Sebastian; Bakker, Karel; Bienhold, Christina; Felden, Janine; Fernández-Méndez, Mar; Hendricks, Stefan; Katlein, Christian; Lalande, Catherine; Krumpen, Thomas; Nicolaus, Marcel; Peeken, Ilka; Rabe, Benjamin; Rogacheva, Antonina; Rybakova, Elena; Somavilla, Raquel; Wenzhöfer, Frank

    2013-03-22

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average 9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function. PMID:23413190

  2. Arctic ozone loss

    SciTech Connect

    Zurer, P.S.

    1989-03-06

    Scientists have returned from the first comprehensive probe of the Arctic stratosphere with unexpectedly dire results: The winter atmosphere in the north polar region is loaded with the same destructive chlorine compounds that cause the Antarctic ozone hole. Atmospheric researchers who only a few weeks ago were comforted by the thought that the warmer Northern Hemisphere is strongly protected from the processes that lead to massive losses of ozone during spring in Antarctica now see very little standing in the way of an Arctic ozone hole.

  3. Fatty acid and stable isotope characteristics of sea ice and pelagic particulate organic matter in the Bering Sea: tools for estimating sea ice algal contribution to Arctic food web production.

    PubMed

    Wang, Shiway W; Budge, Suzanne M; Gradinger, Rolf R; Iken, Katrin; Wooller, Matthew J

    2014-03-01

    We determined fatty acid (FA) profiles and carbon stable isotopic composition of individual FAs (δ(13)CFA values) from sea ice particulate organic matter (i-POM) and pelagic POM (p-POM) in the Bering Sea during maximum ice extent, ice melt, and ice-free conditions in 2010. Based on FA biomarkers, differences in relative composition of diatoms, dinoflagellates, and bacteria were inferred for i-POM versus p-POM and for seasonal succession stages in p-POM. Proportions of diatom markers were higher in i-POM (16:4n-1, 6.6-8.7%; 20:5n-3, 19.6-25.9%) than in p-POM (16:4n-1, 1.2-4.0%; 20:5n-3, 5.5-14.0%). The dinoflagellate marker 22:6n-3/20:5n-3 was highest in p-POM. Bacterial FA concentration was higher in the bottom 1 cm of sea ice (14-245 μg L(-1)) than in the water column (0.6-1.7 μg L(-1)). Many i-POM δ(13)C(FA) values were higher (up to ~10‰) than those of p-POM, and i-POM δ(13)C(FA) values increased with day length. The higher i-POM δ(13)C(FA) values are most likely related to the reduced dissolved inorganic carbon (DIC) availability within the semi-closed sea ice brine channel system. Based on a modified Rayleigh equation, the fraction of sea ice DIC fixed in i-POM ranged from 12 to 73%, implying that carbon was not limiting for primary productivity in the sympagic habitat. These differences in FA composition and δ(13)C(FA) values between i-POM and p-POM will aid efforts to track the proportional contribution of sea ice algal carbon to higher trophic levels in the Bering Sea and likely other Arctic seas. PMID:24276772

  4. Photorespiration and carbon limitation determine productivity in temperate seagrasses.

    PubMed

    Buapet, Pimchanok; Rasmusson, Lina M; Gullström, Martin; Björk, Mats

    2013-01-01

    The gross primary productivity of two seagrasses, Zostera marina and Ruppia maritima, and one green macroalga, Ulva intestinalis, was assessed in laboratory and field experiments to determine whether the photorespiratory pathway operates at a substantial level in these macrophytes and to what extent it is enhanced by naturally occurring shifts in dissolved inorganic carbon (DIC) and O2 in dense vegetation. To achieve these conditions in laboratory experiments, seawater was incubated with U. intestinalis in light to obtain a range of higher pH and O2 levels and lower DIC levels. Gross photosynthetic O2 evolution was then measured in this pretreated seawater (pH, 7.8-9.8; high to low DIC:O2 ratio) at both natural and low O2 concentrations (adjusted by N2 bubbling). The presence of photorespiration was indicated by a lower gross O2 evolution rate under natural O2 conditions than when O2 was reduced. In all three macrophytes, gross photosynthetic rates were negatively affected by higher pH and lower DIC. However, while both seagrasses exhibited significant photorespiratory activity at increasing pH values, the macroalga U. intestinalis exhibited no such activity. Rates of seagrass photosynthesis were then assessed in seawater collected from the natural habitats (i.e., shallow bays characterized by high macrophyte cover and by low DIC and high pH during daytime) and compared with open baymouth water conditions (where seawater DIC is in equilibrium with air, normal DIC, and pH). The gross photosynthetic rates of both seagrasses were significantly higher when incubated in the baymouth water, indicating that these grasses can be significantly carbon limited in shallow bays. Photorespiration was also detected in both seagrasses under shallow bay water conditions. Our findings indicate that natural carbon limitations caused by high community photosynthesis can enhance photorespiration and cause a significant decline in seagrass primary production in shallow waters. PMID

  5. Photorespiration and Carbon Limitation Determine Productivity in Temperate Seagrasses

    PubMed Central

    Buapet, Pimchanok; Rasmusson, Lina M.; Gullström, Martin; Björk, Mats

    2013-01-01

    The gross primary productivity of two seagrasses, Zostera marina and Ruppia maritima, and one green macroalga, Ulva intestinalis, was assessed in laboratory and field experiments to determine whether the photorespiratory pathway operates at a substantial level in these macrophytes and to what extent it is enhanced by naturally occurring shifts in dissolved inorganic carbon (DIC) and O2 in dense vegetation. To achieve these conditions in laboratory experiments, seawater was incubated with U. intestinalis in light to obtain a range of higher pH and O2 levels and lower DIC levels. Gross photosynthetic O2 evolution was then measured in this pretreated seawater (pH, 7.8–9.8; high to low DIC:O2 ratio) at both natural and low O2 concentrations (adjusted by N2 bubbling). The presence of photorespiration was indicated by a lower gross O2 evolution rate under natural O2 conditions than when O2 was reduced. In all three macrophytes, gross photosynthetic rates were negatively affected by higher pH and lower DIC. However, while both seagrasses exhibited significant photorespiratory activity at increasing pH values, the macroalga U. intestinalis exhibited no such activity. Rates of seagrass photosynthesis were then assessed in seawater collected from the natural habitats (i.e., shallow bays characterized by high macrophyte cover and by low DIC and high pH during daytime) and compared with open baymouth water conditions (where seawater DIC is in equilibrium with air, normal DIC, and pH). The gross photosynthetic rates of both seagrasses were significantly higher when incubated in the baymouth water, indicating that these grasses can be significantly carbon limited in shallow bays. Photorespiration was also detected in both seagrasses under shallow bay water conditions. Our findings indicate that natural carbon limitations caused by high community photosynthesis can enhance photorespiration and cause a significant decline in seagrass primary production in shallow waters. PMID

  6. Eocene Arctic Ocean and earth's Early Cenozoic climate

    SciTech Connect

    Clark, D.L.

    1985-01-01

    Seasonal changes of the Arctic Ocean are an approximate microcosm of the present advanced interglacial climate of the Earth. A similar relationship has existed for several million years but was the Early Cenozoic Arctic Ocean an analog of Earth's climate, as well. Absence of polar ice during the Cretaceous is relatively well established. During the Cenozoic a worldwide decrease in mean annual ocean temperature resulted from such factors as altered oceanic circulation and lower atmospheric CO/sub 2/ levels. Limited Arctic Ocean data for the middle or late Eocene indicate the presence of upwelling conditions and accompanying high productivity of diatoms, ebridians, silicoflagellates and archaeomonads. During this interval, some seasonality is suggested from the varve-like nature of a single sediment core. However, the absence of drop stones or any ice-rafted sediment supports the idea of an open water, ice-free central Arctic Ocean during this time. Latest Cretaceous Arctic Ocean sediment is interpreted to represent approximately the same conditions as those suggested for the Eocene and together with that data suggest that the central Arctic Ocean was ice-free during part if not all of the first 20 my of the Cenozoic. Sediment representing the succeeding 30 my has not been recovered but by latest Miocene or earl Pliocene, ice-rafted sediment was accumulating, both pack ice and icebergs covered the Arctic Ocean reflecting cyclic glacial climate.

  7. Arctic ocean sediment texture and the Pleistocene climate cycle

    SciTech Connect

    Clark, D.L.; Morris, T.H.

    1985-01-01

    Arctic Ocean sediment texture accurately reflects the Plio-Pleistocene climate cycle. The precision of paleoclimate interpretation is improved when deglaciation is recognized as a distinct climate stage, overlapping both glacial and interglacial stages, and for the later Pleistocene, perhaps never completed. Oxygen isotope stratigraphy and foraminifera productivity are out of phase but can be understood in the context of the transitional nature of the glacial, deglacial and interglacial climate stages of the Arctic Ocean.

  8. Oceanographic Aspects of Recent Changes in the Arctic

    NASA Astrophysics Data System (ADS)

    Morison, J. H.

    2002-12-01

    climate feedback is that the changes in ocean circulation and ice production have increased the amount of relatively fresh surface water exported to the sub-Arctic Seas, increasing stratification there, and arguably reducing the strength of the global thermohaline circulation. Since the mid-1990s the strength of the Polar Vortex (AO) has relaxed partially toward earlier levels. Recent observations show that Arctic Ocean water mass structure has relaxed somewhat towards climatology near the surface but is still changing at depth. The cold halocline has recovered in some areas. This reinforces the notion that the changes in the Arctic are tied to the atmospheric circulation of the whole northern hemisphere. The events of the last 10-15 years suggest ways the Arctic environment may be an indicator and agent of climate change and highlight the importance of a systematic program to observe the changing Arctic. References Parkinson C. L., D. J. Cavalieri, P. Gloersen, H. J. Zwally, and J. C. Comiso, 1999, Arctic sea ice extents, areas, and trends, 1978-1996, J. Geophys. Res., 104, 20,387-20,856. Rothrock, D. A., Y. Yu, and G. A. Maykut, 1999, Thinning of the Arctic sea-ice cover, Geophys. Res. Lett., 26(23), 3469-3472. Steele, M., and T. Boyd, 1998, Retreat of the cold halocline layer in the Arctic Ocean, J. Geophys. Res., 103, 10,419-10,435.

  9. Circum-Arctic lithospheric transects from onshore to offshore

    NASA Astrophysics Data System (ADS)

    Pease, V.; Coakley, B.; Faleide, J. I.; Jokat, W.; Miller, E. L.; Stephenson, R.; Meisling, K. E.

    2015-12-01

    Understanding the evolution of the lithosphere over time involves the integration and interpretation of geological and geophysical data, combined with good knowledge of the physical processes at work in the lithosphere giving rise to past and present structures. Tectonic activity related to the rifting process created the present-day structure of today's Arctic basins and bathymetric highs, and in the process modified older structures and architecture of the crust and lithosphere. The correlation of circum-Arctic terranes and orogens help to not only reconstruct paleogeography but to also define the role and determine the nature of the lithospheric processes that were active in the complex tectonic evolution of the Arctic. CALE (Circum Arctic Lithosphere Evolution), an international and multidisciplinary effort involving c. 35 geologists and geophysicists from ten different countries working to link the onshore and offshore regions across the circum-Arctic region, is a scientific network in it's last year of a 5-year program. Sedimentary cover and crust to mantle cross-sections from onshore to offshore have been created integrating the latest scientific knowledge and data sets available for the Arctic. The project's principal Arctic transects include: Ellesmere-Canada Basin, Pacific Ocean-Lomonosov Ridge through the Bering Strait, across the Laptev Sea rift to the DeLong Islands, Barents and Kara regions across Timan-Pechora and Taimyr. These sections, the culmination of the CALE project, and their principle findings will be presented for the first time with discussion of outstanding issues yet to be resolved.

  10. Microfaunal evidences for elevated pliocene temperatures in the arctic ocean

    NASA Astrophysics Data System (ADS)

    Cronin, Thomas M.; Whatley, Robin; Wood, Adrian; Tsukagoshi, Akira; Ikeya, Noriyuki; Brouwers, E. M.; Briggs, W. M.

    1993-04-01

    The migration of thermophilic marine Ostracoda into the Arctic Ocean during the Pliocene indicates that winter and summer ocean temperatures around Arctic margins were ≥ 0 °C and > 3 °C, respectively, and that ice-free conditions existed for most or all of the Arctic. By at least 3.5-3.0 Ma, probably earlier, the opening of the Bering Strait allowed marine organisms to migrate through the Arctic Ocean, mostly from the Pacific Ocean. Migrant taxa such as Cythere, Hemicythere, and Neomonoceratina are known from Pliocene deposits of Alaska and Canada as well as Neogene deposits of the North Pacific and Atlantic oceans. On the basis of ecological and Zoogeographic information on ostracode species from more than 800 modern "core top" samples for the North Atlantic, North Pacific, and Arctic Oceans, we determined winter and summer temperature tolerances for migrant taxa to be at or above about 0 °C and 3 °C. This suggests ice-free summers, and probably, a perennially ice-free Arctic Ocean in some regions. Elevated water temperatures in the Arctic Ocean between 3.5 and 2.0 Ma is supported by evidence for late Pliocene increased meridional heat transport in the North Atlantic Ocean.

  11. Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic

    USGS Publications Warehouse

    Geiselman, Joy; DeGange, Anthony R.; Oakley, Karen; Derksen, Dirk; Whalen, Mary

    2012-01-01

    Ecosystems and their wildlife communities are not static; they change and evolve over time due to numerous intrinsic and extrinsic factors. A period of rapid change is occurring in the Arctic for which our current understanding of potential ecosystem and wildlife responses is limited. Changes to the physical environment include warming temperatures, diminishing sea ice, increasing coastal erosion, deteriorating permafrost, and changing water regimes. These changes influence biological communities and the ways in which human communities interact with them. Through the new initiative Changing Arctic Ecosystems (CAE) the U.S. Geological Survey (USGS) strives to (1) understand the potential suite of wildlife population responses to these physical changes to inform key resource management decisions such as those related to the Endangered Species Act, and (2) provide unique insights into how Arctic ecosystems are responding under new stressors. Our studies examine how and why changes in the ice-dominated ecosystems of the Arctic are affecting wildlife and will provide a better foundation for understanding the degree and manner in which wildlife species respond and adapt to rapid environmental change. Changes to Arctic ecosystems will be felt broadly because the Arctic is a production zone for hundreds of species that migrate south for the winter. The CAE initiative includes three major research themes that span Arctic ice-dominated ecosystems and that are structured to identify and understand the linkages between physical processes, ecosystems, and wildlife populations. The USGS is applying knowledge-based modeling structures such as Bayesian Networks to integrate the work.

  12. Arctic lithosphere - A review

    NASA Astrophysics Data System (ADS)

    Pease, V.; Drachev, S.; Stephenson, R.; Zhang, X.

    2014-07-01

    This article reviews the characteristics of Arctic lithosphere and the principal tectonic events which have shaped it. The current state-of-knowledge associated with the crust, crustal-scale discontinuities, and their ages, as well as knowledge of the lithosphere as a whole from geophysical data, permits the division of Arctic lithosphere into discrete domains. Arctic continental lithosphere is diverse in age, composition, and structure. It has been affected by at least two periods of thermal overprinting associated with large volumes of magmatism, once in the Permo-Triassic and again in the Aptian. In addition, it was attenuated as the result of at least five phases of rifting (in the late Devonian-early Carboniferous, Permo-Triassic, Jurassic, Early Cretaceous, and Late Cretaceous-Cenozoic). Older phases of consolidation are associated with continental lithosphere and occurred through a series of continent-continent collisions in the Paleozoic. Jurassic and Cretaceous extensional phases are related to the dismembering of Pangea and Eurasia, and were concentrated in the Norway-Greenland and Canadian-Alaskan Arctic regions. Large areas of submarine, hyperextended continental (?) lithosphere developed in parts of the Amerasia Basin. After continental breakup and the accretion of new oceanic lithosphere, the Eurasia and Canada basins were formed.

  13. Communicating Arctic Change (Invited)

    NASA Astrophysics Data System (ADS)

    Serreze, M.

    2009-12-01

    Nowhere on the planet are emerging signals of climate change more visible than in the Arctic. Rapid warming, a quickly shrinking summer sea ice cover, and thawing permafrost, will have impacts that extend beyond the Arctic and may reverberate around the globe. The National Snow and Ice Data Center (NSIDC) of the University of Colorado has taken a leading role in trying to effectively communicate the science and importance of Arctic change. Our popular “Sea Ice News and Analysis” web site tracks the Arctic’s shrinking ice cover and provides scientific analysis with language that is accurate yet accessible to a wide audience. Our Education Center provides accessible information on all components of the Earth’s cryosphere, the changes being seen, and how scientists conduct research. A challenge faced by NSIDC is countering the increasing level of confusion and misinformation regarding Arctic and global change, a complex problem that reflects the low level of scientific literacy by much of the public, the difficulties many scientists face in communicating their findings in accurate but understandable terms, and efforts by some groups to deliberately misrepresent and distort climate change science. This talk will outline through examples ways in which NSIDC has been successful in science communication and education, as well as lessons learned from failures.

  14. Determining The Dispersibility Of South Louisiana Crude Oil By Eight Oil Dispersant Products Listed On The NCP Product Schedule

    EPA Science Inventory

    We recently conducted a laboratory study to measure the dispersion effectiveness of eight dispersants currently listed on the National Contingency Plan Product Schedule. Results are useful in determining how many commercial dispersant products would have been effective for use o...

  15. The Arctic Circle

    NASA Astrophysics Data System (ADS)

    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

  16. 76 FR 65212 - Product Dynamics LTD, Levittown, PA; Notice of Affirmative Determination Regarding Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... Employment and Training Administration Product Dynamics LTD, Levittown, PA; Notice of Affirmative... apply for Trade Adjustment Assistance (TAA) applicable to workers and former workers of Product Dynamics, LTD, Levittown, Pennsylvania (Product Dynamics). The negative determination was issued on September...

  17. 40 CFR Appendix C to Subpart Nnn... - Method for the Determination of Product Density

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Product Density C Appendix C to Subpart NNN of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Determination of Product Density 1. Purpose The purpose of this test is to determine the product density of... thickness. 3.5Calculate the product density: Density (lb/ft3) = area weight (lb/ft2)/thickness (ft)...

  18. 40 CFR Appendix C to Subpart Nnn... - Method for the Determination of Product Density

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Product Density C Appendix C to Subpart NNN of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Determination of Product Density 1. Purpose The purpose of this test is to determine the product density of... thickness. 3.5Calculate the product density: Density (lb/ft3) = area weight (lb/ft2)/thickness (ft)...

  19. Atmospheric aspects of Arctic change

    NASA Astrophysics Data System (ADS)

    Overland, J. E.

    2011-12-01

    Three important features of recent Arctic change are the rather uniform pattern of Arctic temperature amplification in response to greenhouse gas forcing, the modification of atmospheric temperature and wind patterns over newly sea-ice-free regions, and the possible increased linkage between Arctic climate and sub-arctic weather. An important argument for anthropogenic forcing of recent Arctic change is the model predicted rather uniform increases in Arctic temperatures, in contrast to more regional temperature maximums associated with intrinsic climate variability patterns such as those which occurred during the 1930s Arctic warming. Sea-ice-free areas at the end of summer are allowing: added heat and moisture transport into the troposphere as documented during the recent Japanese vessel Mirai cruises, decreased boundary layer stratification, and modification of wind flow through thermal wind processes. Winter 2009-2010 and December 2010 showed a unique connectivity between the Arctic and more southern weather when the typical polar vortex was replaced by high geopotential heights over the central Arctic and low heights over mid-latitudes that resulted in record snow and low temperatures, a Warm Arctic-Cold Continents pattern. A major challenge of Arctic meteorology is to understand the interaction of forced changes such as loss of sea ice and land impacts with intrinsic climate patterns such as the North Atlantic Oscillation and Pacific North American climate patterns. Could persistent shifts in Arctic climate be triggered by a combination of a gradual upward trend in temperature, an extreme event e.g. fortuitous timing in the natural variability of the atmospheric or ocean general circulation, and Arctic specific feedbacks? Scientific progress on both issues requires sustained decadal observations.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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.

  1. Assessment of undiscovered oil and gas in the arctic

    USGS Publications Warehouse

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

    2009-01-01

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

  2. Artificial Warming of Arctic Meadow under Pollution Stress: Experimental design

    NASA Astrophysics Data System (ADS)

    Moni, Christophe; Silvennoinen, Hanna; Fjelldal, Erling; Brenden, Marius; Kimball, Bruce; Rasse, Daniel

    2014-05-01

    Boreal and arctic terrestrial ecosystems are central to the climate change debate, notably because future warming is expected to be disproportionate as compared to world averages. Likewise, greenhouse gas (GHG) release from terrestrial ecosystems exposed to climate warming is expected to be the largest in the arctic. Artic agriculture, in the form of cultivated grasslands, is a unique and economically relevant feature of Northern Norway (e.g. Finnmark Province). In Eastern Finnmark, these agro-ecosystems are under the additional stressor of heavy metal and sulfur pollution generated by metal smelters of NW Russia. Warming and its interaction with heavy metal dynamics will influence meadow productivity, species composition and GHG emissions, as mediated by responses of soil microbial communities. Adaptation and mitigation measurements will be needed. Biochar application, which immobilizes heavy metal, is a promising adaptation method to promote positive growth response in arctic meadows exposed to a warming climate. In the MeadoWarm project we conduct an ecosystem warming experiment combined to biochar adaptation treatments in the heavy-metal polluted meadows of Eastern Finnmark. In summary, the general objective of this study is twofold: 1) to determine the response of arctic agricultural ecosystems under environmental stress to increased temperatures, both in terms of plant growth, soil organisms and GHG emissions, and 2) to determine if biochar application can serve as a positive adaptation (plant growth) and mitigation (GHG emission) strategy for these ecosystems under warming conditions. Here, we present the experimental site and the designed open-field warming facility. The selected site is an arctic meadow located at the Svanhovd Research station less than 10km west from the Russian mining city of Nikel. A splitplot design with 5 replicates for each treatment is used to test the effect of biochar amendment and a 3oC warming on the Arctic meadow. Ten circular

  3. Improving the representation of Arctic photosynthesis in Earth system models

    NASA Astrophysics Data System (ADS)

    Rogers, A.; Serbin, S.; Ely, K.; Sloan, V. L.; Wyatt, R. A.; Kubien, D. S.; Ali, A. A.; Xu, C.; Wullschleger, S. D.

    2015-12-01

    The primary goal of Earth System Models (ESMs) is to improve understanding and projection of future global change. In order to do this they must accurately represent the carbon fluxes associated with the terrestrial carbon cycle. Although Arctic carbon fluxes are small - relative to global carbon fluxes - uncertainty is large. As part of a multidisciplinary project to improve the representation of the Arctic in ESMs (Next Generation Ecosystem Experiments - Arctic) we are examining the photosynthetic parameterization of the Arctic plant functional type (PFT) in ESMs. Photosynthetic CO2 uptake is well described by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis. Most ESMs use a derivation of the FvCB model to calculate gross primary productivity. Two key parameters required by the FvCB model are an estimate of the maximum rate of carboxylation by the enzyme Rubisco (Vc,max) and the maximum rate of electron transport (Jmax). In ESMs the parameter Vc,max is usually fixed for a given PFT. Only four ESMs currently have an explicit Arctic PFT and the data used to derive Vc,max for the Arctic PFT in these models relies on small data sets and unjustified assumptions. We examined the derivation of Vc,max and Jmax in current Arctic PFTs and estimated Vc,max and Jmax for 7 species representing both dominant vegetation and key Arctic PFTs growing on the Barrow Environmental Observatory, Barrow, AK. The values of Vc,max currently used to represent Arctic PFTs in ESMs are 70% lower than the values we measured in these species. Examination of the derivation of Vc,max in ESMs identified that the cause of the relatively low Vc,max value was the result of underestimating both the leaf N content and the investment of that N in Rubisco. Contemporary temperature response functions for Vc,max also appear to underestimate Vc,max at low temperature. ESMs typically use a single multiplier (JVratio) to convert Vc,max to Jmax for all PFTs. We found that the JVratio of

  4. State of the Arctic Coast 2010: Scientific Review and Outlook

    NASA Astrophysics Data System (ADS)

    Rachold, V.; Forbes, D. L.; Kremer, H.; Lantuit, H.

    2010-12-01

    The coast is a key interface in the Arctic environment. It is a locus of human activity, a rich band of biodiversity, critical habitat, and high productivity, and among the most dynamic components of the circumpolar landscape. The Arctic coastal interface is a sensitive and important zone of interaction between land and sea, a region that provides essential ecosystem services and supports indigenous human lifestyles; a zone of expanding infrastructure investment and growing security concerns; and an area in which climate warming is expected to trigger landscape instability, rapid responses to change, and increased hazard exposure. Starting with a collaborative workshop in October 2007, the International Arctic Science Committee (IASC), the Land-Ocean Interactions in the Coastal Zone (LOICZ) Project and the International Permafrost Association (IPA) decided to jointly initiate an assessment of the state of the Arctic coast. The goal of this report is to draw on initial findings regarding climate change and human dimensions for the Arctic as a whole provided by the Arctic Climate Impact Assessment (ACIA) and Arctic Human Development Report (AHDR) to develop a comprehensive picture of status and current and anticipated change in the most sensitive Arctic coastal areas. Underlying is the concept of a social ecological system perspective that explores the implications of change for the interaction of humans with nature. The report is aimed to be a first step towards a continuously updated coastal assessment and to identify key issues seeking future scientific concern in an international Earth system research agenda. The report titled “State of the Arctic Coast 2010: Scientific Review and Outlook” is the outcome of this collaborative effort. It is organized in three parts: the first provides an assessment of the state of Arctic coastal systems under three broad disciplinary themes - physical systems, ecological systems, and human concerns in the coastal zone; the

  5. Biological Chlorine Cycling in Arctic Peat Soils

    NASA Astrophysics Data System (ADS)

    Zlamal, J. E.; Raab, T. K.; Lipson, D.

    2014-12-01

    . Incubations were conducted in the laboratory providing arctic soils with Clorg, and measurements taken to assess rates of organohalide respiration show an increase in chloride production due to microbial activity. Investigating these soils with diverse techniques affirms the importance of Cl-cycling in a pristine arctic tundra ecosystem.

  6. A Synthesis of Arctic Weather and Climate

    NASA Astrophysics Data System (ADS)

    Bromwich, D. H.; Hines, K. M.

    2008-12-01

    In the polar regions, its is difficult to place current weather and climate trends in a long-term climatological perspective, primarily because the meteorological records there are limited in time and space in comparison with other regions of the globe. The low spatial density of polar meteorological data makes it challenging to attribute changes to local effects or to hemispheric teleconnections. Reanalyses, which assimilate all available observations into physically-consistent, regularly-spaced and comprehensive datasets, can be especially helpful in these latitudes. The timeliness of such efforts is especially pronounced given the recently-observed dramatic changes in Arctic sea ice, land ice, and permafrost regions, whose causes are being debated. A new physically-consistent synthesis of Arctic observations will be achieved through the high-resolution reanalysis of the northern high latitude region, spanning poleward from the headwaters of the northward flowing rivers. The ASR is a collaboration of the Ohio State University, the National Center Atmospheric Research, the University of Colorado, the University of Illinois, and the University of Alaska-Fairbanks. The production phase of the initial ASR has been funded by the National Science Foundation as an International Polar Year (IPY 2007-2009) project covering 2000-2010. The ASR will provide a high resolution description in space (15 km) and time (1-3 h) of the coupled atmosphere-sea ice-land surface system of the Arctic. Ingested historical data streams from the surface and space, along with measurements of the physical components of the Arctic Observing Network being developed as part of IPY will be assimilated by the ASR. Gridded output fields from the ASR will serve a variety of uses such drivers for coupled ice-ocean, land surface and other models, and will offer a focal point for coordinated model inter-comparison efforts. The ASR will permit detailed reconstructions of the Arctic system's variability

  7. Annual arctic wolf pack size related to arctic hare numbers

    USGS Publications Warehouse

    Mech, L.D.

    2007-01-01

    During the summers of 2000 through 2006, I counted arctic wolf (Canis lupus arctos) pups and adults in a pack, arctic hares (Lepus arcticus) along a 9 km index route in the area, and muskoxen (Ovibos moschatus) in a 250 km2 part of the area near Eureka (80?? N, 86?? W), Ellesmere Island, Nunavut, Canada. Adult wolf numbers did not correlate with muskox numbers, but they were positively related (r2 = 0.89; p < 0.01) to an arctic hare index. This is the first report relating wolf numbers to non-ungulate prey. ?? The Arctic Institute of North America.

  8. Modeling the summertime Arctic cloudy boundary layer

    SciTech Connect

    Curry, J.A.; Pinto, J.O.; McInnes, K.L.

    1996-04-01

    Global climate models have particular difficulty in simulating the low-level clouds during the Arctic summer. Model problems are exacerbated in the polar regions by the complicated vertical structure of the Arctic boundary layer. The presence of multiple cloud layers, a humidity inversion above cloud top, and vertical fluxes in the cloud that are decoupled from the surface fluxes, identified in Curry et al. (1988), suggest that models containing sophisticated physical parameterizations would be required to accurately model this region. Accurate modeling of the vertical structure of multiple cloud layers in climate models is important for determination of the surface radiative fluxes. This study focuses on the problem of modeling the layered structure of the Arctic summertime boundary-layer clouds and in particular, the representation of the more complex boundary layer type consisting of a stable foggy surface layer surmounted by a cloud-topped mixed layer. A hierarchical modeling/diagnosis approach is used. A case study from the summertime Arctic Stratus Experiment is examined. A high-resolution, one-dimensional model of turbulence and radiation is tested against the observations and is then used in sensitivity studies to infer the optimal conditions for maintaining two separate layers in the Arctic summertime boundary layer. A three-dimensional mesoscale atmospheric model is then used to simulate the interaction of this cloud deck with the large-scale atmospheric dynamics. An assessment of the improvements needed to the parameterizations of the boundary layer, cloud microphysics, and radiation in the 3-D model is made.

  9. NIR spectroscopy for determining soy contents in processed meat products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soy products such as soy concentrate, soy protein and soy grits are used as a meat extender in processed meat products to improve meat texture. However, soy allergies are one of the common food allergies, especially in infants and young children, and can be mild to life-threatening. The United State...

  10. SONARC: A Sea Ice Monitoring and Forecasting System to Support Safe Operations and Navigation in Arctic Seas

    NASA Astrophysics Data System (ADS)

    Stephenson, S. R.; Babiker, M.; Sandven, S.; Muckenhuber, S.; Korosov, A.; Bobylev, L.; Vesman, A.; Mushta, A.; Demchev, D.; Volkov, V.; Smirnov, K.; Hamre, T.

    2015-12-01

    Sea ice monitoring and forecasting systems are important tools for minimizing accident risk and environmental impacts of Arctic maritime operations. Satellite data such as synthetic aperture radar (SAR), combined with atmosphere-ice-ocean forecasting models, navigation models and automatic identification system (AIS) transponder data from ships are essential components of such systems. Here we present first results from the SONARC project (project term: 2015-2017), an international multidisciplinary effort to develop novel and complementary ice monitoring and forecasting systems for vessels and offshore platforms in the Arctic. Automated classification methods (Zakhvatkina et al., 2012) are applied to Sentinel-1 dual-polarization SAR images from the Barents and Kara Sea region to identify ice types (e.g. multi-year ice, level first-year ice, deformed first-year ice, new/young ice, open water) and ridges. Short-term (1-3 days) ice drift forecasts are computed from SAR images using feature tracking and pattern tracking methods (Berg & Eriksson, 2014). Ice classification and drift forecast products are combined with ship positions based on AIS data from a selected period of 3-4 weeks to determine optimal vessel speed and routing in ice. Results illustrate the potential of high-resolution SAR data for near-real-time monitoring and forecasting of Arctic ice conditions. Over the next 3 years, SONARC findings will contribute new knowledge about sea ice in the Arctic while promoting safe and cost-effective shipping, domain awareness, resource management, and environmental protection.

  11. The role of ice nuclei recycling in the maintenance of cloud ice in Arctic mixed-phase stratocumulus

    DOE PAGESBeta

    Solomon, A.; Feingold, G.; Shupe, M. D.

    2015-04-21

    This study investigates the maintenance of cloud ice production in Arctic mixed phase stratocumulus in large-eddy simulations that include a prognostic ice nuclei (IN) formulation and a diurnal cycle. Balances derived from a mixed-layer model and phase analyses are used to provide insight into buffering mechanisms that maintain ice in these cloud systems. We find that for the case under investigation, IN recycling through subcloud sublimation considerably prolongs ice production over a multi-day integration. This effective source of IN to the cloud dominates over mixing sources from above or below the cloud-driven mixed layer. Competing feedbacks between dynamical mixing andmore » recycling are found to slow the rate of ice lost from the mixed layer when a diurnal cycle is simulated. The results of this study have important implications for maintaining phase partitioning of cloud ice and liquid that determine the radiative forcing of Arctic mixed-phase clouds.« less

  12. The role of ice nuclei recycling in the maintenance of cloud ice in Arctic mixed-phase stratocumulus

    DOE PAGESBeta

    Solomon, A.; Feingold, G.; Shupe, M. D.

    2015-09-25

    This study investigates the maintenance of cloud ice production in Arctic mixed-phase stratocumulus in large eddy simulations that include a prognostic ice nuclei (IN) formulation and a diurnal cycle. Balances derived from a mixed-layer model and phase analyses are used to provide insight into buffering mechanisms that maintain ice in these cloud systems. We find that, for the case under investigation, IN recycling through subcloud sublimation considerably prolongs ice production over a multi-day integration. This effective source of IN to the cloud dominates over mixing sources from above or below the cloud-driven mixed layer. Competing feedbacks between dynamical mixing andmore » recycling are found to slow the rate of ice lost from the mixed layer when a diurnal cycle is simulated. The results of this study have important implications for maintaining phase partitioning of cloud ice and liquid that determine the radiative forcing of Arctic mixed-phase clouds.« less

  13. Arctic River organic matter transport

    NASA Astrophysics Data System (ADS)

    Raymond, Peter; Gustafsson, Orjan; Vonk, Jorien; Spencer, Robert; McClelland, Jim

    2016-04-01

    Arctic Rivers have unique hydrology and biogeochemistry. They also have a large impact on the Arctic Ocean due to the large amount of riverine inflow and small ocean volume. With respect to organic matter, their influence is magnified by the large stores of soil carbon and distinct soil hydrology. Here we present a recap of what is known of Arctic River organic matter transport. We will present a summary of what is known of the ages and sources of Arctic River dissolved and particulate organic matter. We will also discuss the current status of what is known about changes in riverine organic matter export due to global change.

  14. The Greening of the Arctic IPY Project

    NASA Astrophysics Data System (ADS)

    Walker, D. A.; Bhatt, U. S.; Epstein, H. E.

    2008-12-01

    In 2007, Arctic sea ice extent declined to the lowest level in recorded history, 24 percent lower than the previous record in 2005. If the Arctic continues to warm over the next few decades as predicted by most arctic scientists, large changes in vegetation biomass will occur and will have important consequences to many components of the Arctic system including status of the permafrost, hydrological cycles, wildlife, and human occupation. There will also be important feedbacks to climate through changes in albedo and carbon fluxes. Changes in biomass are already happening. In Arctic Alaska from 1981 to 2001, the greenness of the landscapes as measured by satellite-derived values of the normalized difference vegetation index (NDVI) increased by 17 percent. It is uncertain what this remarkable change in greenness means with respect to plant biomass, but current NDVI-biomass relationships suggest that an average of over 100 g m-2 have been added to the tundra of northern Alaska within the past twenty years. Other studies have shown a major increase of shrub cover across northern Alaska during the past 50 years. If the Arctic Ocean becomes ice- free during the summer, some of the largest percentage increases could occur in the coldest parts of the Arctic. The three major objectives of this project are: (1) establish baseline ground observations along two transects in North American and Eurasia that traverse the entire Arctic bioclimate gradient; (2) use remote sensing and climate change analysis to determine how changes in sea ice concentrations affect land-surface temperature and the NDVI, (3) use vegetation-change models to predict how vegetation will change in the future. Strong correlations exist between sea-ice concentrations, land-surface temperatures, and the maximum and integrated NDVI). The changes in greening have been strongest in the Beaufort Sea region. Between 1982 and 2007, sea ice in the 50-km coastal strip of Beaufort Sea area during the period 18 June

  15. Sources of Information as Determinants of Product and Process Innovation

    PubMed Central

    2016-01-01

    In this paper we use a panel of manufacturing firms in Spain to examine the extent to which they use internal and external sources of information (customers, suppliers, competitors, consultants and universities) to generate product and process innovation. Our results show that, although internal sources are influential, external sources of information are key to achieve innovation performance. These results are in line with the open innovation literature because they show that firms that are opening up their innovation process and that use different information sources have a greater capacity to generate innovations. We also find that the importance of external sources of information varies depending on the type of innovation (product or process) considered. To generate process innovation, firms mainly rely on suppliers while, to generate product innovation, the main contribution is from customers. The potential simultaneity between product and process innovation is also taken into consideration. We find that the generation of both types of innovation is not independent. PMID:27035456

  16. Sources of Information as Determinants of Product and Process Innovation.

    PubMed

    Gómez, Jaime; Salazar, Idana; Vargas, Pilar

    2016-01-01

    In this paper we use a panel of manufacturing firms in Spain to examine the extent to which they use internal and external sources of information (customers, suppliers, competitors, consultants and universities) to generate product and process innovation. Our results show that, although internal sources are influential, external sources of information are key to achieve innovation performance. These results are in line with the open innovation literature because they show that firms that are opening up their innovation process and that use different information sources have a greater capacity to generate innovations. We also find that the importance of external sources of information varies depending on the type of innovation (product or process) considered. To generate process innovation, firms mainly rely on suppliers while, to generate product innovation, the main contribution is from customers. The potential simultaneity between product and process innovation is also taken into consideration. We find that the generation of both types of innovation is not independent. PMID:27035456

  17. Arctic thermal design

    SciTech Connect

    Lunardini, V.J.

    1985-05-01

    Arctic engineering theories and techniques are discussed. The problems associated with ameliorating cold-climate effects is examined. External accumulation of ice on solid surfaces, floating ice sheets, icebergs, multiyear ice, and ice ridges are discussed, and the problems associated with these hazards are analyzed. The author believes that it is possible to deal rationally with these problems if the engineer is aware of them, and that ignorance can cause spectacular failures in the cold regions.

  18. Arctic offshore platform

    SciTech Connect

    Bhula, D.N.

    1984-01-24

    An offshore structure is disclosed for use in drilling and producing wells in arctic regions having a conical shaped lower portion that extends above the surface of the water and a cylindrical upper section. The conical portion is provided with a controlled stiffness outer surface for withstanding the loads produced by ice striking the structure. The stiffness properties of the outer shell and flexible members are designed to distribute the load and avoid high local loads on the inner parts of the structure.

  19. Empirical Determination of Radiolytic Products in Simulated Europan Ices

    NASA Technical Reports Server (NTRS)

    Hand, P.; Carlson, R. W.; Chyba, C. F.

    2004-01-01

    The chemical composition of Europa's surface is strongly influenced by energetic charge particle bombardment from Jupiter's magnetosphere. Here we report on progress in experimental work designed to address: 1) The production of radiolytic products in thermodynamic disequilibrium that could be utilized by known terrestrial microorganisms, and 2) The modification of complex organic molecules and degradation of biological material by the simulated Europan surface radiation environment.

  20. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a)...

  1. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a)...

  2. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a)...

  3. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a)...

  4. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The Administrator will, within ninety (90)...

  5. Eastern-western Arctic sea ice analysis, 1993

    SciTech Connect

    1993-12-31

    This publication is the 20th edition of the annual Arctic sea-ice atlases prepared by the JIC. The atlas contains weekly charts depicting Northern Hemisphere ice conditions and extent. The significant use of high resolution satellite imagery, combined with valuable ice reconnaissance data from various sources, has greatly improved the accuracy of these analyses. The purpose of this atlas is to provide the user with reliable weekly hemispheric ice analyses. These charts are prepared by experienced Navy and NOAA ice analysts who plot and evaluate numerous data sources: (a) Conventional shore station, ship, and aerial reconnaissance observations; and (b) Satellite data from various sensors. Table I, located on the inside back cover, lists these sensors and their availability. A final product is synthesized from the inputs described above. When insufficient data is available, estimated boundaries are plotted, using meteorological data and computer generated ice drift vectors to determine estimated ice position.

  6. Changes to freshwater systems affecting Arctic infrastructure and natural resources

    NASA Astrophysics Data System (ADS)

    Instanes, Arne; Kokorev, Vasily; Janowicz, Richard; Bruland, Oddbjørn; Sand, Knut; Prowse, Terry

    2016-03-01

    The resources component of the Arctic Freshwater Synthesis focuses on the potential impact of future climate and change on water resources in the Arctic and how Arctic infrastructure and exploration and production of natural resources are affected. Freshwater availability may increase in the Arctic in the future in response to an increase in middle- and high-latitude annual precipitation. Changes in type of precipitation, its seasonal distribution, timing, and rate of snowmelt represent a challenge to municipalities and transportation networks subjected to flooding and droughts and to current industries and future industrial development. A reliable well-distributed water source is essential for all infrastructures, industrial development, and other sectorial uses in the Arctic. Fluctuations in water supply and seasonal precipitation and temperature may represent not only opportunities but also threats to water quantity and quality for Arctic communities and industrial use. The impact of future climate change is varying depending on the geographical area and the current state of infrastructure and industrial development. This paper provides a summary of our current knowledge related to the system function and key physical processes affecting northern water resources, industry, and other sectorial infrastructure.

  7. Mercury bioaccumulation and biomagnification in a small Arctic polynya ecosystem.

    PubMed

    Clayden, Meredith G; Arsenault, Lilianne M; Kidd, Karen A; O'Driscoll, Nelson J; Mallory, Mark L

    2015-03-15

    Recurring polynyas are important areas of biological productivity and feeding grounds for seabirds and mammals in the Arctic marine environment. In this study, we examined food web structure (using carbon and nitrogen isotopes, δ(13)C and δ(15)N) and mercury (Hg) bioaccumulation and biomagnification in a small recurring polynya ecosystem near Nasaruvaalik Island (Nunavut, Canada). Methyl Hg (MeHg) concentrations increased by more than 50-fold from copepods (Calanus hyperboreus) to Arctic terns (Sterna paradisaea), the abundant predators at this site. The biomagnification of MeHg through members of the food web - using the slope of log MeHg versus δ(15)N - was 0.157 from copepods (C. hyperboreus) to fish. This slope was higher (0.267) when seabird chicks were included in the analyses. Collectively, our results indicate that MeHg biomagnification is occurring in this small polynya and that its trophic transfer is at the lower end of the range of estimates from other Arctic marine ecosystems. In addition, we measured Hg concentrations in some poorly studied members of Arctic marine food webs [e.g. Arctic alligatorfish (Ulcina olrikii) and jellyfish, Medusozoa], and found that MeHg concentrations in jellyfish were lower than expected given their trophic position. Overall, these findings provide fundamental information about food web structure and mercury contamination in a small Arctic polynya, which will inform future research in such ecosystems and provide a baseline against which to assess changes over time resulting from environmental disturbance. PMID:25149682

  8. Air cushion vehicles for arctic operation

    NASA Astrophysics Data System (ADS)

    Koleser, J.; Lavis, D. R.

    1986-09-01

    Attention is given to the results of the NAVSEA FY85 Surface Ship Concept Formulation Design Study for an initial operational capability year-2000 air cushion vehicle (ACV) suitable for logistics and general search/rescue duties in the Arctic. Two designs were developed during the study; the first utilized an ACV design synthesis math model while the second evolved as a derivative of an existing U.S. production craft. Both are regarded as feasible from an engineering and naval architectural standpoint. Results of performance and cost trade-off studies suggest that, for an Arctic ACV, gas turbines are the preferred power plant choice and an aluminum alloy is the preferred hull structural material choice. The most appropriate skirt height is approximately 12 ft.

  9. Future emissions from shipping and petroleum activities in the Arctic

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  10. Impacts of a Warming Arctic - Arctic Climate Impact Assessment

    NASA Astrophysics Data System (ADS)

    Arctic Climate Impact Assessment

    2004-12-01

    The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels. Impacts of a Warming Arctic is a plain language synthesis of the key findings of the Arctic Climate Impact Assessment (ACIA), designed to be accessible to policymakers and the broader public. The ACIA is a comprehensively researched, fully referenced, and independently reviewed evaluation of arctic climate change. It has involved an international effort by hundreds of scientists. This report provides vital information to society as it contemplates its responses to one of the greatest challenges of our time. It is illustrated in full color throughout.

  11. Using Web Surveys to Determine Audience Characteristics and Product Preferences

    ERIC Educational Resources Information Center

    Philbrick, Jane Hass; Smith, F. Ruth; Bart, Barbara

    2010-01-01

    A web survey is a cost-effective and efficient method to use when measuring the characteristics of an audience and developing or testing new product concepts. This paper reports on the use of a web survey by a start-up media/internet firm, Farmers' Almanac TV. The results indicate that using email to contact respondents from a client list results…

  12. 7 CFR 760.813 - Determination of production.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... assistance loans with an intended use of grain but harvested as silage, ensilage, cobbage, hay, cracked, rolled, or crimped, production will be adjusted based on a whole grain equivalent as established by FSA..., regardless of their disposition or use, as adjusted for low quality. (k) For tobacco, the actual...

  13. Quantitative determination of major polyphenol constituents in pomegranate products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The anti-oxidant content and potential health benefits associated with consuming pomegranate and pomegranate-containing products has lead to increased consumer demand for pomegranate resulting in pomegranate becoming a high value crop. The potential health benefits and high anti-oxidant content of ...

  14. 40 CFR Appendix C to Subpart Nnn... - Method for the Determination of Product Density

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Product Density C Appendix C to Subpart NNN of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Product Density 1. Purpose The purpose of this test is to determine the product density of cured blanket... product density: Density (lb/ft3) = area weight (lb/ft2)/thickness (ft)...

  15. The Arctic Circumpolar Boundary Current

    NASA Astrophysics Data System (ADS)

    Aksenov, Yevgeny; Ivanov, Vladimir V.; Nurser, A. J. George; Bacon, Sheldon; Polyakov, Igor V.; Coward, Andrew C.; Naveira-Garabato, Alberto C.; Beszczynska-Moeller, Agnieszka

    2011-09-01

    We present high-resolution simulations and observational data as evidence of a fast current flowing along the shelf break of the Siberian and Alaskan shelves in the Arctic Ocean. Thus far, the Arctic Circumpolar Boundary Current (ACBC) has been seen as comprising two branches: the Fram Strait and Barents Sea Branches (FSB and BSB, respectively). Here we describe a new third branch, the Arctic Shelf Break Branch (ASBB). We show that the forcing mechanism for the ASBB is a combination of buoyancy loss and non-local wind, creating high pressure upstream in the Barents Sea. The potential vorticity influx through the St. Anna Trough dictates the cyclonic direction of flow of the ASBB, which is the most energetic large-scale circulation structure in the Arctic Ocean. It plays a substantial role in transporting Arctic halocline waters and exhibits a robust seasonal cycle with a summer minimum and winter maximum. The simulations show the continuity of the FSB all the way around the Arctic shelves and the uninterrupted ASBB between the St. Anna Trough and the western Fram Strait. The BSB flows continuously along the Siberian shelf as far as the Chukchi Plateau, where it partly diverges from the continental slope into the ocean interior. The Alaskan Shelf break Current (ASC) is the analog of the ASBB in the Canadian Arctic. The ASC is forced by the local winds and high upstream pressure in Bering Strait, caused by the drop in sea surface height between the Pacific and Arctic Oceans.

  16. Offshore outlook: the American Arctic

    SciTech Connect

    Jahns, M.O.

    1985-05-01

    Offshore areas in the American Arctic are highlighted and the development of the area is compared with other offshore areas where the required technology is more readily available. Principal areas are shown in which new concepts are being put to practice. Canada's east coast is examined. Several technological trends are reviewed to help operators accelerate the discovery and development of arctic petroleum reserves.

  17. Quantifying the Arctic methane budget

    NASA Astrophysics Data System (ADS)

    Warwick, Nicola; Cain, Michelle; Pyle, John

    2014-05-01

    The Arctic is a major source of atmospheric methane, containing climate-sensitive emissions from natural wetlands and gas hydrates, as well as the fossil fuel industry. Both wetland and gas hydrate methane emissions from the Arctic may increase with increasing temperature, resulting in a positive feedback leading to enhancement of climate warming. It is important that these poorly-constrained sources are quantified by location and strength and their vulnerability to change be assessed. The MAMM project (Methane and other greenhouse gases in the Arctic: Measurements, process studies and Modelling') addresses these issues as part of the UK NERC Arctic Programme. A global chemistry transport model has been used, along with MAMM and other long term observations, to assess our understanding of the different source and sink terms in the Arctic methane budget. Simulations including methane coloured by source and latitude are used to distinguish between Arctic seasonal variability arising from transport and that arising from changes in Arctic sources and sinks. Methane isotopologue tracers provide a further constraint on modelled methane variability, distinguishing between isotopically light and heavy sources (e.g. wetlands and gas fields). We focus on quantifying the magnitude and seasonal variability of Arctic wetland emissions.

  18. Determination of Trace Water Content in Petroleum and Petroleum Products.

    PubMed

    Frink, Lillian A; Armstrong, Daniel W

    2016-08-16

    Measurement of water in petroleum and petroleum-based products is of industrial and economic importance; however, the varied and complex matrixes make the analyses difficult. These samples tend to have low amounts of water and contain many compounds which react with iodine, causing Karl Fischer titration (KFT) to give inaccurate, typically higher, results. A simple, rapid, automated headspace gas chromatography (HSGC) method which requires modified instrumentation and ionic liquid stationary phases was developed. Measurement of water in 12 petroleum products along with 3 National Institute of Standards and Technology reference materials was performed with the developed method. The range of water found in these samples was ∼12-3300 ppm. This approach appeared to be unaffected by complicated matrixes. The solvent-free nature of the HSGC method also negates the solubility limitations which are common with KFT. PMID:27463946

  19. 40 CFR 600.511-80 - Determination of domestic production.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Regulations for Model Year 1978 Passenger Automobiles and for 1979 and Later Model Year Automobiles (Light Trucks and Passenger Automobiles)-Procedures for Determining Manufacturer's Average Fuel Economy and...) Except with advance approval of the Administrator, an automobile shall be considered...

  20. 40 CFR 600.511-80 - Determination of domestic production.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Regulations for Model Year 1978 Passenger Automobiles and for 1979 and Later Model Year Automobiles (Light Trucks and Passenger Automobiles)-Procedures for Determining Manufacturer's Average Fuel Economy § 600... automobile shall be considered domestically produced in any model year if it is included within...

  1. Mentoring Prospective Principals: Determinants of Productive Mentor-Mentee Relationship

    ERIC Educational Resources Information Center

    Schechter, Chen

    2014-01-01

    Mentoring contributes to prospective principals' growth, easing their transition from the role of teacher to that of administrator. This article reports findings from a study aimed at examining the determinant factors affecting the mentor-mentee relationship in a uniquely designed principal preparation program in New York City. The study…

  2. Subsurface plankton layers in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Churnside, James H.; Marchbanks, Richard D.

    2015-06-01

    The first synoptic measurements of subsurface plankton layers were made in the western Arctic Ocean in July 2014 using airborne lidar. Layers were detected in open water and in pack ice where up to 90% of the surface was covered by ice. Layers under the ice were less prevalent, weaker, and shallower than those in open water. Layers were more prevalent in the Chukchi Sea than in the Beaufort Sea. Three quarters of the layers observed were thinner than 5 m. The presence of these layers, which are not adequately captured in satellite data, will influence primary productivity, secondary productivity, fisheries recruitment, and carbon export to the benthos.

  3. Arctic Submarine Slope Stability

    NASA Astrophysics Data System (ADS)

    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

  4. Acute toxicity of eight oil spill response chemicals to temperate, boreal, and Arctic species.

    PubMed

    Hansen, Bjørn Henrik; Altin, Dag; Bonaunet, Kristin; Overjordet, Ida Beathe

    2014-01-01

    The objectives of this study were to (1) determine the acute toxicity of selected shoreline washing agents (SWA) and dispersants, and (2) assess interspecies differences in sensitivity to the products. Eight shoreline washing agents (Hela saneringsvæske, Bios, Bioversal, Absorrep K212, and Corexit 9580) and chemical dispersants (Corexit 9500, Dasic NS, and Gamlen OD4000) were tested on five marine species, algae Skeletonema costatum, planktonic copepod species Acartia tonsa (temperate species), Calanus finmarchicus (boreal species) and Calanus glacialis (Arctic species), and benthic amphipod Corophium volutator. For most products, A. tonsa was the most sensitive species, whereas C. volutator was the least sensitive; however, these species were exposed through different media (water/sediment). In general, all copepod species displayed a relatively similar sensitivity to all products. However, A. tonsa was somewhat more sensitive than other copepods to most of the tested products. Thus, A. tonsa appears to be a candidate species for boreal and Arctic copepods for acute toxicity testing, and data generated on this species may be used as to provide conservative estimates. The benthic species (C. volutator) had a different sensitivity pattern relative to pelagic species, displaying higher sensitivity to solvent-based SWA than to water-based SWA. Comparing product toxicity, the dispersants were in general most toxic while the solvent-based SWA were least toxic to pelagic species. PMID:24754387

  5. Arctic Summer Ice Processes

    NASA Technical Reports Server (NTRS)

    Holt, Benjamin

    1999-01-01

    The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open

  6. Arctic hydrology and meteorology

    SciTech Connect

    Kane, D.L.

    1990-01-01

    During 1990, we have continued our meteorological and hydrologic data collection in support of our process-oriented research. The six years of data collected to data is unique in its scope and continuity in a North Hemisphere Arctic setting. This valuable data base has allowed us to further our understanding of the interconnections and interactions between the atmosphere/hydrosphere/biosphere/lithosphere. The increased understanding of the heat and mass transfer processes has allowed us to increase our model-oriented research efforts.

  7. Determination of alternative fuels combustion products: Phase 1 report

    SciTech Connect

    Whitney, K.A.

    1997-09-01

    This report describes the laboratory effort to identify and quantify organic exhaust species generated from alternative-fueled light-duty vehicles operating over the Federal Test Procedure on compressed natural gas, liquefied petroleum gas, methanol, ethanol, and reformulated gasoline. The exhaust species from these vehicles were identified and quantified for fuel/air equivalence ratios of 0.8, 1.0, and 1.2, nominally, and were analyzed with and without a vehicle catalyst in place to determine the influence of a catalytic converter on species formation.

  8. Determination of alternative fuels combustion products: Phase 2 final report

    SciTech Connect

    Whitney, K.A.

    1997-06-01

    This report describes the laboratory efforts to accomplish four independent tasks: (1) speciation of hydrocarbon exhaust emissions from a light-duty vehicle operated over the chassis dynamometer portion of the light-duty FTP after modifications for operation on butane and butane blends; (2) evaluation of NREL`s Variable Conductance Vacuum Insulated Catalytic Converter Test Article 4 for the reduction of cold-start FTP exhaust emissions after extended soak periods for a Ford FFV Taurus operating on E85; (3) support of UDRI in an attempt to define correlations between engine-out combustion products identified by SwRI during chassis dynamometer testing, and those found during flow tube reactor experiments conducted by UDRI; and (4) characterization of small-diameter particulate matter from a Ford Taurus FFV operating in a simulated fuel-rich failure mode on CNG, LPG, M85, E85, and reformulated gasoline. 22 refs., 18 figs., 17 tabs.

  9. Arctic geodynamics: Arctic science and ERS-1 satellite altimetry

    NASA Technical Reports Server (NTRS)

    Anderson, Allen Joel; Sandwell, David T.

    1994-01-01

    A detailed gravity field map of the mid Arctic Ocean, spreading ridge system was produced on the basis of ERS-1 satellite altimetry data. Areas of special concern, the Barents and Kara Seas, and areas surrounding the islands of Svalbard, Frans Josef Land and Novoya Zemlya are reviewed. ERS-1 altimetry covers unique Arctic and Antarctic latitudes above 72 degrees. Before ERS-1 it was not possible to study these areas with satellite altimetry. Gravity field solutions for the Barents Sea, portions of the Arctic Ocean and the Norwegian sea are shown. The largest gravity anomalies occur along the Greenland fracture zone as well as along transform faults near Svalbard.

  10. Determination of optimum oven cooking procedures for lean beef products.

    PubMed

    Rodas-González, Argenis; Larsen, Ivy L; Uttaro, Bethany; Juárez, Manuel; Parslow, Joyce; Aalhus, Jennifer L

    2015-11-01

    In order to determine optimum oven cooking procedures for lean beef, the effects of searing at 232 or 260°C for 0, 10, 20 or 30 min, and roasting at 160 or 135°C on semimembranosus (SM) and longissimus lumborum (LL) muscles were evaluated. In addition, the optimum determined cooking method (oven-seared for 10 min at 232°C and roasted at 135°C) was applied to SM roasts varying in weight from 0.5 to 2.5 kg. Mainly, SM muscles seared for 0 or 10 min at 232°C followed by roast at 135°C had lower cooking loss, higher external browning color, more uniform internal color, and were more tender and flavorful (P < 0.05). Roast weights ≥1 kg had lesser cooking loss, more uniform internal color and tender compared to 0.5 kg (P < 0.05). Consequently, roasting at low temperature without searing is the recommended oven cooking procedure; with best response from muscle roast weight ≥1 kg. PMID:26788289

  11. FRAM - FRontiers in Arctic marine Monitoring: Permanent Observations in a Gateway to the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Soltwedel, Thomas

    2015-04-01

    Our ability to understand the complex interactions of biological, chemical, physical, and geological processes in the ocean is still limited by the lack of integrative and interdisciplinary observation infrastructures. The main purpose of the open-ocean infrastructure FRAM (FRontiers in Arctic marine Monitoring) is permanent presence at sea, from surface to depth, for the provision of near real-time data on climate variability and ecosystem change in an Arctic marine environment. The Alfred-Wegener-Institut I Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), together with partner institutes in Germany and Europe, aims at providing such infrastructure for the polar ocean as a major contribution to international efforts towards comprehensive Global Earth Observation. The FRAM Ocean Observing System targets the gateway between the North Atlantic and the Central Arctic, representing a highly climate-sensitive and rapidly changing region of the Earth system. It will serve national and international tasks towards a better understanding of the effects of change in ocean circulation, water mass properties and sea-ice retreat on Arctic marine ecosystems and their main functions and services. FRAM integrates and develops already existing observatories, i.e. the oceanographic mooring array HAFOS (Hybrid Arctic/Antarctic Float Observing System) and the Long-Term Ecological Research (LTER) site HAUSGARTEN. It will implement existing and next-generation sensors and observatory platforms, allowing synchronous observation of relevant ocean variables, as well as the study of physical, chemical and biological processes in the water column and at the seafloor. Experimental and event-triggered platforms will complement observational platforms. Products of the infrastructure are continuous long-term data with appropriate resolution in space and time, as well as ground-truthing information for ocean models and remote sensing.

  12. Brominated organic species in the arctic atmosphere

    NASA Technical Reports Server (NTRS)

    Berg, W. W.; Heidt, L. E.; Pollock, W.; Sperry, P. D.; Cicerone, R. J.; Gladney, E. S.

    1984-01-01

    Measurements are reported of four gas-phase, brominated organic species found in the Arctic atmosphere during March and April 1983. Volume mixing ratios for CH3Br, CH2BrCH2Br, CHBr3, and CH2Br2 were determined by gas chromatography/mass spectrometry analysis from samples taken Arctic wide, including at the geographic North Pole and during a tropopause folding event over Baffin Bay near Thule, Greenland. Methyl bromide mixing ratios were reasonably constant at 11 plus or minus 4 pptv, while the other three brominated organics showed a high degree of variability. Bromoform (2 to 46 pptv) was found to be the dominant contributor to gaseous organic bromine to the Arctic troposphere at 38 plus or minus 10 percent followed by CH2Br2 (3 to 60 pptv) at 29 plus or minus 6 percent. Both CH3Br and CH2BrCH2Br (1 to 37 pptv) reservoirs contained less than 20 percent of the organically bound bromine. Stratospheric samples, taken during a tropopause folding event, showed mixing ratios for all four species at levels high enough to support a stratospheric total volume mixing ratio of 249 pptv Br (888 ngBr/SCM).

  13. Solubility and Solubility Product Determination of a Sparingly Soluble Salt: A First-Level Laboratory Experiment

    ERIC Educational Resources Information Center

    Bonomo, Raffaele P.; Tabbi, Giovanni; Vagliasindi, Laura I.

    2012-01-01

    A simple experiment was devised to let students determine the solubility and solubility product, "K"[subscript sp], of calcium sulfate dihydrate in a first-level laboratory. The students experimentally work on an intriguing equilibrium law: the constancy of the product of the ion concentrations of a sparingly soluble salt. The determination of…

  14. 30 CFR 202.550 - How do I determine the royalty due on gas production?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... value, the royalty due is the unit value of production for royalty purposes, determined under 30 CFR... 30 Mineral Resources 2 2010-07-01 2010-07-01 false How do I determine the royalty due on gas production? 202.550 Section 202.550 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE...

  15. 40 CFR Appendix C to Subpart Nnn... - Method for the Determination of Product Density

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Density C Appendix C to Subpart NNN of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., Subpt. NNN, App. C Appendix C to Subpart NNN of Part 63—Method for the Determination of Product Density 1. Purpose The purpose of this test is to determine the product density of cured blanket...

  16. 40 CFR Appendix C to Subpart Nnn... - Method for the Determination of Product Density

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Density C Appendix C to Subpart NNN of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., Subpt. NNN, App. C Appendix C to Subpart NNN of Part 63—Method for the Determination of Product Density 1. Purpose The purpose of this test is to determine the product density of cured blanket...

  17. 78 FR 17933 - Determination That BENADRYL (diphenhydramine hydrochloride) Injection and Two Other Drug Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-25

    ...) Injection and Two Other Drug Products Were Not Withdrawn From Sale for Reasons of Safety or Effectiveness...) has determined that the three drug products listed in this document were not withdrawn from ] sale for... or effectiveness, or if FDA determines that the listed drug was withdrawn from sale for reasons...

  18. Climate-derived tensions in Arctic security.

    SciTech Connect

    Backus, George A.; Strickland, James Hassler

    2008-09-01

    Globally, there is no lack of security threats. Many of them demand priority engagement and there can never be adequate resources to address all threats. In this context, climate is just another aspect of global security and the Arctic just another region. In light of physical and budgetary constraints, new security needs must be integrated and prioritized with existing ones. This discussion approaches the security impacts of climate from that perspective, starting with the broad security picture and establishing how climate may affect it. This method provides a different view from one that starts with climate and projects it, in isolation, as the source of a hypothetical security burden. That said, the Arctic does appear to present high-priority security challenges. Uncertainty in the timing of an ice-free Arctic affects how quickly it will become a security priority. Uncertainty in the emergent extreme and variable weather conditions will determine the difficulty (cost) of maintaining adequate security (order) in the area. The resolution of sovereignty boundaries affects the ability to enforce security measures, and the U.S. will most probably need a military presence to back-up negotiated sovereignty agreements. Without additional global warming, technology already allows the Arctic to become a strategic link in the global supply chain, possibly with northern Russia as its main hub. Additionally, the multinational corporations reaping the economic bounty may affect security tensions more than nation-states themselves. Countries will depend ever more heavily on the global supply chains. China has particular needs to protect its trade flows. In matters of security, nation-state and multinational-corporate interests will become heavily intertwined.

  19. Arctic sea ice albedo from AVHRR

    SciTech Connect

    Lindsay, R.W.; Rothrock, D.A.

    1994-11-01

    The seasonal cycle of surface albedo of sea ice in the Arctic is estimated from measurements made with the Advanced Very High Resolution Radiometer (AVHRR) on the polar-orbiting satellites NOAA-10 and NOAA-11. The albedos of 145 200-km-square cells are analyzed. The cells are from March through September 1989 and include only those for which the sun is more than 10 deg above the horizon. Cloud masking is performed manually. Corrections are applied for instrument calibration, nonisotropic reflection, atmospheric interference, narrowband to broadband conversion, and normalization to a common solar zenith angle. The estimated albedos are relative, with the instrument gain set to give an albedo of 0.80 for ice floes in March and April. The mean values for the cloud-free portions of individual cells range from 0.18 to 0.91. Monthly averages of cells in the central Arctic range from 0.76 in April to 0.47 in August. The monthly averages of the within-cell standard deviations in the central Arctic are 0.04 in April and 0.06 in September. The surface albedo and surface temperature are correlated most strongly in March (R = -0.77) with little correlation in the summer. The monthly average lead fraction is determined from the mean potential open water, a scaled representation of the temperature or albedo between 0.0 (for ice) and 1.0 (for water); in the central Arctic it rises from an average 0.025 in the spring to 0.06 in September. Sparse data on aerosols, ozone, and water vapor in the atmospheric column contribute uncertainties to instantaneous, area-average albedos of 0.13, 0.04, and 0.08. Uncertainties in monthly average albedos are not this large. Contemporaneous estimation of these variables could reduce the uncertainty in the estimated albedo considerably.

  20. Carbon cycle uncertainty in the Alaskan Arctic

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Sikka, M.; Oechel, W. C.; Huntzinger, D. N.; Melton, J. R.; Koven, C. D.; Ahlström, A.; Arain, M. A.; Baker, I.; Chen, J. M.; Ciais, P.; Davidson, C.; Dietze, M.; El-Masri, B.; Hayes, D.; Huntingford, C.; Jain, A. K.; Levy, P. E.; Lomas, M. R.; Poulter, B.; Price, D.; Sahoo, A. K.; Schaefer, K.; Tian, H.; Tomelleri, E.; Verbeeck, H.; Viovy, N.; Wania, R.; Zeng, N.; Miller, C. E.

    2014-08-01

    Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for the Alaskan Arctic from four recent model intercomparison projects - NACP (North American Carbon Program) site and regional syntheses, TRENDY (Trends in net land atmosphere carbon exchanges), and WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) - we provide a baseline of terrestrial carbon cycle uncertainty, defined as the multi-model standard deviation (σ) for each quantity that follows. Mean annual absolute uncertainty was largest for soil carbon (14.0 ± 9.2 kg C m-2), then gross primary production (GPP) (0.22 ± 0.50 kg C m-2 yr-1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m-2 yr-1), net primary production (NPP) (0.14 ± 0.33 kg C m-2 yr-1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m-2 yr-1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m-2 yr-1), net ecosystem exchange (NEE) (-0.01 ± 0.19 kg C m-2 yr-1), and CH4 flux (2.52 ± 4.02 g CH4 m-2 yr-1). There were no consistent spatial patterns in the larger Alaskan Arctic and boreal regional carbon stocks and fluxes, with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic and larger boreal region.

  1. Factors controlling seasonal variations in Arctic black carbon

    NASA Astrophysics Data System (ADS)

    Shen, Z.; Ming, Y.; Horowitz, L. W.

    2015-12-01

    Arctic haze has a distinct seasonality with higher concentrations in winter and spring. This study evaluates how different processes of large-scale circulation and removal control seasonal variations in Arctic black carbon (BC) using the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric general circulation model (AM3). We find that transport and wet deposition play unequal roles in determining Arctic BC seasonal cycle. Despite seasonal differences in general circulation patterns, the eddy-driven BC transport changes little throughout the year, and the seasonal cycle of Arctic BC is attributed to wet removal. BC hydrophilic fraction affected by the aging process and hydrophilic BC (BCpi) wet deposition rate affected by cloud microphysics determine wet deposition. Both low hydrophilic fraction and low wet deposition rate account for the peak of BC in winter. The transition to low BC in summer results from an increase in wet deposition rate, while the return of BC in late autumn is mainly caused by a sharp decrease in hydrophilic fraction. The results suggest that the concentrations of Arctic aerosols as well as their climate impacts may be susceptible to modification in a future climate.

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

    SciTech Connect

    Kaustinen, O.M.

    1982-06-01

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

  3. Determination of alternative fuels combustion products: Phase 3 report

    SciTech Connect

    Whitney, K.A.

    1997-12-01

    This report describes the laboratory efforts to characterize particulate and gaseous exhaust emissions from a passenger vehicle operating on alternative fuels. Tests were conducted at room temperature (nominally 72 F) and 20 F utilizing the chassis dynamometer portion of the FTP for light-duty vehicles. Fuels evaluated include Federal RFG, LPG meeting HD-5 specifications, a national average blend of CNG, E85, and M85. Exhaust particulate generated at room temperature was further characterized to determine polynuclear aromatic content, trace element content, and trace organic constituents. For all fuels except M85, the room temperature particulate emission rate from this vehicle was about 2 to 3 mg/mile. On M85, the particulate emission rate was more than 6 mg/mile. In addition, elemental analysis of particulate revealed an order of magnitude more sulfur and calcium from M85 than any other fuel. The sulfur and calcium indicate that these higher emissions might be due to engine lubricating oil in the exhaust. For RFG, particulate emissions at 20 F were more than six times higher than at room temperature. For alcohol fuels, particulate emissions at 20 F were two to three times higher than at room temperature. For CNG and LPG, particulate emissions were virtually the same at 72 F and 20 F. However, PAH emissions from CNG and LPG were higher than expected. Both gaseous fuels had larger amounts of pyrene, 1-nitropyrene, and benzo(g,h,i)perylene in their emissions than the other fuels.

  4. Sweden sees Arctic, subsea challenges

    SciTech Connect

    LeBlanc, L.A.

    1984-02-01

    Marine research organizations in Sweden are developing solutions in three broad areas of maritime research - Artic and sub-Arctic technology, underwater engineerng and marine environment monitoring. One of the Arctic projects already under way is a solution to safe navigation through the Arctic ice pack. Icebergs and deep-keeled ice ridges are imbedded in the ice pack and present a hazard to transiting vessels. Underwater programs are being established to deal with the problem of poor underwater visibilty due to turbid water conditions near the bottom. A device is being tested which will allow a diver or submerged vehicle to be accurately tracked using short-baseline acoustics.

  5. 21 CFR 601.26 - Reclassification procedures to determine that licensed biological products are safe, effective...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or... Reclassification procedures to determine that licensed biological products are safe, effective, and not misbranded... for the reclassification of all biological products that have been classified into Category IIIA....

  6. 21 CFR 601.26 - Reclassification procedures to determine that licensed biological products are safe, effective...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or... Reclassification procedures to determine that licensed biological products are safe, effective, and not misbranded... for the reclassification of all biological products that have been classified into Category IIIA....

  7. 21 CFR 601.26 - Reclassification procedures to determine that licensed biological products are safe, effective...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or... Reclassification procedures to determine that licensed biological products are safe, effective, and not misbranded... for the reclassification of all biological products that have been classified into Category IIIA....

  8. 21 CFR 601.26 - Reclassification procedures to determine that licensed biological products are safe, effective...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or... Reclassification procedures to determine that licensed biological products are safe, effective, and not misbranded... for the reclassification of all biological products that have been classified into Category IIIA....

  9. 21 CFR 601.26 - Reclassification procedures to determine that licensed biological products are safe, effective...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or... Reclassification procedures to determine that licensed biological products are safe, effective, and not misbranded... for the reclassification of all biological products that have been classified into Category IIIA....

  10. 30 CFR 1202.550 - How do I determine the royalty due on gas production?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... purposes, determined under 30 CFR part 1206, multiplied by the volume of production multiplied by the... production? 1202.550 Section 1202.550 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR Natural Resources Revenue ROYALTIES Gas Production From Indian Leases §...

  11. Mars: New Determination of Impact Crater Production Function Size Distribution

    NASA Astrophysics Data System (ADS)

    Hartmann, William K.

    2006-12-01

    Several authors have questioned our knowledge of Martian impact crater production function size-frequency distribution (PFSFD), especially at small diameters D. Plescia (2005) questioned whether any area of Mars shows size distributions used for estimating crater retention ages on Mars. McEwen et al. (2005) and McEwen and Bierhaus (2006) suggested existing PFSFD’s are hopelessly confused by the presence of secondaries, and that my isochrons give primary crater densities off by factors of several thousand at small D. In 2005, I addressed some of these concerns, noting my curves do not estimate primary crater densities per se, but show total numbers of primaries + semi-randomly “distant secondaries” (negating many McEwen et al. critiques). In 2006 I have conducted new crater counts on a PFSFD test area suggested by Ken Tanaka. This area shows young lava flows of similar crater density, west of Olympus Mons (around 30 deg N, 100 deg W). Multiple crater counts were made on several adjacent Odyssey THEMIS images and MGS MOC images, giving the SFD over a range of 11m

  12. Observing Arctic Ecology using Networked Infomechanical Systems

    NASA Astrophysics Data System (ADS)

    Healey, N. C.; Oberbauer, S. F.; Hollister, R. D.; Tweedie, C. E.; Welker, J. M.; Gould, W. A.

    2012-12-01

    2012. Once compiled and quality controlled, all of our data are freely available online via the Arctic Observing Network's Advanced Cooperative Arctic Data and Information Service (ACADIS). Here we present some of our findings to show how our results can be advantageous to various disciplines including plant ecology, hydrology, geology, atmospheric sciences, and remote sensing. For instance, we found that albedo decreases with increasing NDVI after initial green-up and loss of dead standing litter (DOY 174-184), displaying an r2 of 0.90 in 2012 at Toolik Lake. This relationship is vital for determining phonological events via remote sensing and understanding the surface energy balance that impacts atmospheric processes, weather and climate, the hydrologic cycle, and ecophysiological progression throughout the short arctic growing season. Scaling these data to larger scales, which is critical to future monitoring of the potential impacts of climate change on arctic vegetation, is facilitated by linkage of measurements along the NIMS transects and manual vegetation measurements in the 1 km2 sample grids with frequent low-altitude aerial photography.

  13. Evidence and Implications of Recent Climate Change in Terrestrial Regions of the Arctic

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.; Bettez, N.; Chapin, F. S.; Dyurgerov, M.; Fastie, C.; Griffith, D. B.; Hope, A.; Huntington, H. P.; Jensen, A.; Kane, D. L.; Kofinas, G.; Lynch, A.; Lloyd, A.; McGuire, A. D.; Nelson, F. E.; Osterkamp, T.; Oechel, W. C.; Racine, C.; Romanovsky, V. E.; Schimel, J.; Stow, D.; Sturm, M.; Tweedie, C. E.; Vourlitis, G.; Walker, M.; Webber, P. J.; Welker, J.; Winker, K.; Yoshikawa, K.

    2002-12-01

    Are changes occurring in the polar terrestrial regime? Is the distribution of permafrost and Arctic region freeze and thaw changing? Is the hydrology of Arctic terrestrial regions changing? Are significant changes occurring in the distribution and productivity of high-latitude vegetation? If one examines any individual scientific discipline, evidence of climate change in arctic regions offers only pieces of the puzzle. Here we present a broad array of evidence to provide a convincing case of change in the arctic climate and a system-wide response of terrestrial processes. The thermal regime of the Arctic holds unique characteristics and consequently will display marked changes in response to climate warming. In many cases, threshold changes will occur in physical systems proceeding from permanently frozen to periodically thawed. Dramatic changes also accompany biological systems adapting to an evolving environment. In the last 25 to 400 years a wide range of changes in the Arctic have been detected. In many cases, these changes started, or accelerated, in the mid-1970s. Some of the changes, like later freeze-up and earlier break-up of arctic rivers and lakes, mirror arctic-wide and even global increases in air temperature. Others document more subtle or complex responses of the arctic system as it adapts to current and longer-term trends in climate. Since the arctic system is particularly sensitive to changes in rain- and snowfall, timing of freeze-up and break-up, and the intensity of storm activity, it is likely that much of what has been documented to date, and will be observed in the future, arises from changes in these forcing fields. Unfortunately, compared with temperature, they are poorly known. Regardless of the driving forces, however, the combined observations and documentation offer diffuse but substantial evidence that the arctic system may be entering a state not seen before in recent history.

  14. World's wetlands. [Ecology and productivity

    SciTech Connect

    Patrick, R.

    1981-02-01

    The 70 million acres of wetlands represent a valuable US resource, providing spawning and nursery grounds for animals, productive areas for photosynthesis, cleansing water, and absorbing floods. Wetlands perform a valuable function in species diversification by nurturing vulnerable plants and animals. The formation of peat affects the carbon dioxide cycle by slowing the recycling of carbon dioxide. Research is needed to determine what will happen as development in the Arctic zones destroys peat and wetlands. (DCK)

  15. CO2 dynamics of tundra ponds in the low-Arctic, Northwest Territories, Canada

    NASA Astrophysics Data System (ADS)

    Buell, Mary-Claire

    Extensive research has gone into measuring changes to the carbon storage capacity of Arctic terrestrial environments as well as large water bodies in order to determine a carbon budget for many regions across the Arctic. Inland Arctic waters such as small lakes and ponds are often excluded from these carbon budgets, however a handful of studies have demonstrated that they can often be significant sources of carbon to the atmosphere. This study investigated the CO2 cycling of tundra ponds in the Daring Lake area, Northwest Territories, Canada (64°52'N, 111°35'W), to determine the role ponds have in the local carbon cycle. Floating chambers, nondispersive infrared (NDIR) sensors and headspace samples were used to estimate carbon fluxes from four selected local ponds. Multiple environmental, chemical and meteorological parameters were also monitored for the duration of the study, which took place during the snow free season of 2013. Average CO2 emissions for the two-month growing season ranged from approximately -0.0035 g CO2-C m-2 d -1 to 0.12 g CO2-C m-2 d-1. The losses of CO2 from the water bodies in the Daring Lake area were approximately 2-7% of the CO2 uptake over vegetated terrestrial tundra during the same two-month period. Results from this study indicated that the production of CO2 in tundra ponds was positively influenced by both increases in air temperature, and the delivery of carbon from their catchments. The relationship found between temperature and carbon emissions suggests that warming Arctic temperatures have the potential to increase carbon emissions from ponds in the future. The findings in this study did not include ebullition gas emissions nor plant mediated transport, therefore these findings are likely underestimates of the total carbon emissions from water bodies in the Daring Lake area. This study emphasizes the need for more research on inland waters in order to improve our understanding of the total impact these waters may have on the

  16. Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils.

    PubMed

    Wild, Birgit; Gentsch, Norman; Čapek, Petr; Diáková, Kateřina; Alves, Ricardo J Eloy; Bárta, Jiři; Gittel, Antje; Hugelius, Gustaf; Knoltsch, Anna; Kuhry, Peter; Lashchinskiy, Nikolay; Mikutta, Robert; Palmtag, Juri; Schleper, Christa; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Torsvik, Vigdis L; Urich, Tim; Watzka, Margarete; Šantrůčková, Hana; Guggenberger, Georg; Richter, Andreas

    2016-01-01

    Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called "priming effect" might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming. PMID:27157964

  17. Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils

    PubMed Central

    Wild, Birgit; Gentsch, Norman; Čapek, Petr; Diáková, Kateřina; Alves, Ricardo J. Eloy; Bárta, Jiři; Gittel, Antje; Hugelius, Gustaf; Knoltsch, Anna; Kuhry, Peter; Lashchinskiy, Nikolay; Mikutta, Robert; Palmtag, Juri; Schleper, Christa; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Torsvik, Vigdis L.; Urich, Tim; Watzka, Margarete; Šantrůčková, Hana; Guggenberger, Georg; Richter, Andreas

    2016-01-01

    Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called “priming effect” might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming. PMID:27157964

  18. Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils

    NASA Astrophysics Data System (ADS)

    Wild, Birgit; Gentsch, Norman; Čapek, Petr; Diáková, Kateřina; Alves, Ricardo J. Eloy; Bárta, Jiři; Gittel, Antje; Hugelius, Gustaf; Knoltsch, Anna; Kuhry, Peter; Lashchinskiy, Nikolay; Mikutta, Robert; Palmtag, Juri; Schleper, Christa; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Torsvik, Vigdis L.; Urich, Tim; Watzka, Margarete; Šantrůčková, Hana; Guggenberger, Georg; Richter, Andreas

    2016-05-01

    Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called “priming effect” might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming.

  19. Climate change and Arctic parasites.

    PubMed

    Dobson, Andy; Molnár, Péter K; Kutz, Susan

    2015-05-01

    Climate is changing rapidly in the Arctic. This has important implications for parasites of Arctic ungulates, and hence for the welfare of Arctic peoples who depend on caribou, reindeer, and muskoxen for food, income, and a focus for cultural activities. In this Opinion article we briefly review recent work on the development of predictive models for the impacts of climate change on helminth parasites and other pathogens of Arctic wildlife, in the hope that such models may eventually allow proactive mitigation and conservation strategies. We describe models that have been developed using the metabolic theory of ecology. The main strength of these models is that they can be easily parameterized using basic information about the physical size of the parasite. Initial results suggest they provide important new insights that are likely to generalize to a range of host-parasite systems. PMID:25900882

  20. The Arctic's Role in Climate.

    ERIC Educational Resources Information Center

    Baker, D. James

    1986-01-01

    Discusses the special role the Arctic region plays in climate, focusing on: (1) the global energy balance; (2) feedback mechanisms; (3) effects of increasing carbon dioxide; and (4) climate processes study programs. (JN)

  1. 2013 Arctic Sea Ice Minimum

    NASA Video Gallery

    After an unusually cold summer in the northernmost latitudes, Arctic sea ice appears to have reached its annual minimum summer extent for 2013 on Sept. 13, the NASA-supported National Snow and Ice ...

  2. Arctic Sea Ice Minimum, 2015

    NASA Video Gallery

    This animation shows the evolution of the Arctic sea ice cover from its wintertime maximum extent, which was reached on Feb. 25, 2015, and was the lowest on record, to its apparent yearly minimum, ...

  3. The Arctic National Wildlife Refuge: An Interdisciplinary Unit.

    ERIC Educational Resources Information Center

    Thieman, Gayle; Geil, Mike

    This paper presents a set of interdisciplinary lessons for teaching about the Arctic National Wildlife Refuge (Alaska). Lessons include a petroleum product treasure hunt, an examination of life without petroleum, the development of a wildlife poster, an exploration of the tundra ecosystem and the plants and animals that live there, identification…

  4. Is there a 230Th deficit in Arctic sediments?

    NASA Astrophysics Data System (ADS)

    Hoffmann, Sharon; McManus, Jerry

    2007-06-01

    In most of the global ocean, the radionuclide thorium-230 is removed from the water column by adsorption onto particles and deposition in seafloor sediments, at a rate approximately in balance with its local production by the decay of uranium dissolved in seawater, allowing its use in assessing rates of marine processes. However, several previous studies have suggested that the flux of 230Th to the sediments of the Central Arctic is far too small to balance its production in the overlying water column. If this is so, 230Th produced in the low particle-flux Central Arctic basins would be deposited elsewhere, either by boundary scavenging at the margins or by export from the Arctic to lower latitudes. In order to evaluate this possibility, we compare the expected 230Th production and measured inventories for five sites in the Western Arctic, combining previously published 230Th data with reported AMS radiocarbon dates, and find no evidence for a substantial deficit of 230Th in these sediments. Instead, we find evidence for near balance in the 230Th budget during both the Holocene and late glacial periods. These intervals are separated by a brief deglacial period of apparently higher sedimentation rates and 230Th deposition. During the Holocene, the average sedimentary inventory of 230Th at these sites is largely within 30% of the water column production, in good agreement with observations and model results from other ocean basins.

  5. The Circumpolar Arctic vegetation map

    USGS Publications Warehouse

    Walker, Donald A.; Raynolds, Martha K.; Daniels, F.J.A.; Einarsson, E.; Elvebakk, A.; Gould, W.A.; Katenin, A.E.; Kholod, S.S.; Markon, C.J.; Melnikov, E.S.; Moskalenko, N.G.; Talbot, S. S.; Yurtsev, B.A.; Bliss, L.C.; Edlund, S.A.; Zoltai, S.C.; Wilhelm, M.; Bay, C.; Gudjonsson, G.; Ananjeva, G.V.; Drozdov, D.S.; Konchenko, L.A.; Korostelev, Y.V.; Ponomareva, O.E.; Matveyeva, N.V.; Safranova, I.N.; Shelkunova, R.; Polezhaev, A.N.; Johansen, B.E.; Maier, H.A.; Murray, D.F.; Fleming, Michael D.; Trahan, N.G.; Charron, T.M.; Lauritzen, S.M.; Vairin, B.A.

    2005-01-01

    Question: What are the major vegetation units in the Arctic, what is their composition, and how are they distributed among major bioclimate subzones and countries? Location: The Arctic tundra region, north of the tree line. Methods: A photo-interpretive approach was used to delineate the vegetation onto an Advanced Very High Resolution Radiometer (AVHRR) base image. Mapping experts within nine Arctic regions prepared draft maps using geographic information technology (ArcInfo) of their portion of the Arctic, and these were later synthesized to make the final map. Area analysis of the map was done according to bioclimate subzones, and country. The integrated mapping procedures resulted in other maps of vegetation, topography, soils, landscapes, lake cover, substrate pH, and above-ground biomass. Results: The final map was published at 1:7 500 000 scale map. Within the Arctic (total area = 7.11 x 106 km 2), about 5.05 ?? 106 km2 is vegetated. The remainder is ice covered. The map legend generally portrays the zonal vegetation within each map polygon. About 26% of the vegetated area is erect shrublands, 18% peaty graminoid tundras, 13% mountain complexes, 12% barrens, 11% mineral graminoid tundras, 11% prostrate-shrub tundras, and 7% wetlands. Canada has by far the most terrain in the High Arctic mostly associated with abundant barren types and prostrate dwarf-shrub tundra, whereas Russia has the largest area in the Low Arctic, predominantly low-shrub tundra. Conclusions: The CAVM is the first vegetation map of an entire global biome at a comparable resolution. The consistent treatment of the vegetation across the circumpolar Arctic, abundant ancillary material, and digital database should promote the application to numerous land-use, and climate-change applications and will make updating the map relatively easy. ?? IAVS; Opulus Press.

  6. Public Perceptions of Arctic Change

    NASA Astrophysics Data System (ADS)

    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

  7. EOS Aqua AMSR-E Arctic Sea Ice Validation Program: Arctic2003 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus,T.

    2003-01-01

    In March 2003 a coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products to be validated include sea ice concentration, sea ice temperature, and snow depth on sea ice. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. Two additional flights were dedicated to making heat and moisture flux measurements over the St. Lawrence Island polynya to support ongoing air-sea-ice processes studies of Arctic coastal polynyas. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound.

  8. Soot in the Arctic

    SciTech Connect

    Rosen, H.; Novakov, T.; Bodhaine, B. A.

    1981-01-01

    In this paper, substantial concentrations of graphitic carbon and its associated large optical absorption coefficient are observed in the Arctic. The graphitic content shows a dramatic increase from late fall to early spring, reaching levels that are comparable to those found in urban environments (i.e., the peak values in February are only about a factor of 10 less than the average levels found in New York City and a factor of three less than those found in Berkeley, California, and Denver, Colorado). Finally, if one ignores the possible contribution of natural burning processes which are expected to be small during this time of the year in the northern hemisphere, this graphitic component can be attributed directly to anthropogenic activity.

  9. Tracking and responding to a changing Arctic sea-ice cover: How ice users can help the scientific community design better observing systems (Louis Agassiz Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Eicken, Hajo

    2010-05-01

    The Arctic sea-ice cover is undergoing a major transformation, with substantial reductions in summer ice extent reflecting changes in ice thickness, age, and circulation. These changes are impacting Arctic ecosystems and a range of human activities. Anticipating and responding to such impacts, exacerbated by increasing economic activity in parts of the Arctic, requires a foundation of environmental observations and model predictions. Recent increases in industrial activities such as shipping and resource development in parts of the Arctic have further highlighted the need for an integrated observing system. In the case of a changing sea-ice cover, how would one best design and optimize such a system? One of the challenges is to meet the information needs of the scientific community in furthering fundamental understanding of the Arctic system, as well as those of key stakeholders and society, helping them to prepare for and respond to Arctic change. This presentation focuses on how the concept of sea-ice system services, i.e., the uses and benefits (or harm) derived from sea ice, may help guide the implementation of an effective observing system. Principal service categories are (1) sea ice as climate regulator, marine hazard, and coastal buffer; (2) transportation and use of ice as a platform; (3) cultural services obtained from the "icescape"; and (4) support of food webs and biological diversity by sea ice. An analysis of the different ice services provided to different user groups can help prioritize different types of observations and determine optimal measurement strategies. Moreover, the focus on different uses of the ice cover may also help synthesize fundamental and applied research to help Arctic communities adapt in a changing environment. Alaska has experienced some of the most substantial changes in sea-ice conditions throughout the Arctic over the past three decades and is used to illustrate the concepts discussed above. Specifically, we have examined

  10. Arctic spring awakening - Steering principles behind the phenology of vernal ice algal blooms

    NASA Astrophysics Data System (ADS)

    Leu, E.; Mundy, C. J.; Assmy, P.; Campbell, K.; Gabrielsen, T. M.; Gosselin, M.; Juul-Pedersen, T.; Gradinger, R.

    2015-12-01

    Marine ecosystems at high latitudes are characterized by extreme seasonal changes in light conditions, as well as a limited period of high primary production during spring and early summer. As light returns at the end of winter to Arctic ice-covered seas, a first algal bloom takes place in the bottom layer of the sea ice. This bottom ice algae community develops through three distinct phases in the transition from winter to spring, starting with phase I, a predominantly net heterotroph community that has limited interaction with the pelagic or benthic realms. Phase II begins in the spring once light for photosynthesis becomes available at the ice bottom, although interaction with the water column and benthos remains limited. The transition to the final phase III is then mainly driven by a balance of atmospheric and oceanographic forcing that induce structural changes in the sea ice and ultimately the removal of algal biomass from the ice. Due to limited data availability an incomplete understanding exists of all the processes determining ice algal bloom phenology and the considerable geographic differences in sympagic algal standing stocks and primary production. We present here the first pan-Arctic compilation of available time-series data on vernal sea ice algal bloom development and identify the most important factors controlling its development and termination. Using data from the area surrounding Resolute Bay (Nunavut, Canada) as an example, we support previous investigations that snow cover on top of the ice influences sea ice algal phenology, with highest biomass development, but also earliest termination of blooms, under low snow cover. We also provide a pan-Arctic overview of sea ice algae standing stocks and primary production, and discuss the pertinent processes behind the geographic differences we observed. Finally, we assess potential future changes in vernal algal bloom phenology as a consequence of climate change, including their importance to

  11. Arctic Coastal Erosion Modeling

    NASA Astrophysics Data System (ADS)

    Ravens, T. M.; Jones, B.; Zhang, J.; Tweedie, C. E.; Erikson, L. H.; Gibbs, A.; Richmond, B. M.

    2011-12-01

    A process-based coastal erosion/shoreline change model has been developed for Arctic coastal bluffs subject to niche erosion/block collapse. The model explicitly accounts for many environmental/geographic variables including: water temperature, water level, wave height, and bluff height. The model was originally developed for a small coastal segment near Drew Point, Beaufort Sea, Alaska. This coastal setting has experienced a dramatic increase in erosion since the early 2000's. The bluffs at this site are 3-4 m tall and consist of ice-wedge bounded blocks of fine-grained sediments cemented by ice-rich permafrost and capped with a thin organic layer. The bluffs are typically fronted by a narrow (~ 5 m wide) beach or none at all. During a storm surge, the sea contacts the base of the bluff and a niche is formed through thermal and mechanical erosion. The niche grows both vertically and laterally and eventually undermines the bluff, leading to block failure or collapse. The fallen block is then eroded both thermally and mechanically by waves and currents, which must occur before a new niche forming episode may begin. The model has been calibrated based on shoreline change data at Drew Point for two time periods: 1979-2002 and 2002-2007. Measured and modeled shoreline change rates were about 8 m/yr and 16 m/yr, for the earlier and later periods, respectively. In this paper, this work is extended to include modeling and measurement of coastal erosion at Drew Point on an annual basis for the period 2007-2010. In addition, the model is applied at three other Arctic coastal locations - Elson Lagoon, Cape Halkett, and Barter Island - where niche erosion/block collapse prevails.

  12. Arctic Sea ice model sensitivities.

    SciTech Connect

    Peterson, Kara J.; Bochev, Pavel Blagoveston; Paskaleva, Biliana Stefanova

    2010-12-01

    Arctic sea ice is an important component of the global climate system and, due to feedback effects, the Arctic ice cover is changing rapidly. Predictive mathematical models are of paramount importance for accurate estimates of the future ice trajectory. However, the sea ice components of Global Climate Models (GCMs) vary significantly in their prediction of the future state of Arctic sea ice and have generally underestimated the rate of decline in minimum sea ice extent seen over the past thirty years. One of the contributing factors to this variability is the sensitivity of the sea ice state to internal model parameters. A new sea ice model that holds some promise for improving sea ice predictions incorporates an anisotropic elastic-decohesive rheology and dynamics solved using the material-point method (MPM), which combines Lagrangian particles for advection with a background grid for gradient computations. We evaluate the variability of this MPM sea ice code and compare it with the Los Alamos National Laboratory CICE code for a single year simulation of the Arctic basin using consistent ocean and atmospheric forcing. Sensitivities of ice volume, ice area, ice extent, root mean square (RMS) ice speed, central Arctic ice thickness,and central Arctic ice speed with respect to ten different dynamic and thermodynamic parameters are evaluated both individually and in combination using the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA). We find similar responses for the two codes and some interesting seasonal variability in the strength of the parameters on the solution.

  13. Arctic energy technologies workshop: proceedings

    SciTech Connect

    Not Available

    1985-04-01

    The objectives of this ''Arctic Energy Technologies Workshop'' were threefold: To acquaint participants with the current US Department of Energy, Office of Fossil Energy, Arctic and Offshore Research Program. To obtain information on Arctic oil and gas development problem areas, and on current and planned research. To provide an opportunity for technical information exchange among engineers, geologists, geophysicists, physical scientists, oceanographers, statisticians, analysts, and other participants engaged in similar research areas. The first section of the proceedings is the keynote address ''Current Arctic Offshore Technology'', presented by Kenneth Croasdale, of K.R. Croasdale and Associates, Ltd., Calgary, Alberta, Canada. The second section of the proceedings includes 14 technical papers presented in two sessions at the Workshop: Sea Ice Research, and Seafloor/Soils Research. The third section of the proceedings includes the summaries of four work-group discussion sessions from the second day of the meeting: (1) Arctic Offshore Structures, (2) Arctic Offshore Pipelines, (3) Subice Development Systems, and (4) Polar-Capable Ice Vessels. The work groups addressed state-of-the-art, technical issues, R and D needs, and environmental concerns in these four areas. All papers in this proceedings have been processed for inclusion in the Energy Data Base.

  14. Rough-legged buzzards, Arctic foxes and red foxes in a tundra ecosystem without rodents.

    PubMed

    Pokrovsky, Ivan; Ehrich, Dorothée; Ims, Rolf A; Kondratyev, Alexander V; Kruckenberg, Helmut; Kulikova, Olga; Mihnevich, Julia; Pokrovskaya, Liya; Shienok, Alexander

    2015-01-01

    Small rodents with multi-annual population cycles strongly influence the dynamics of food webs, and in particular predator-prey interactions, across most of the tundra biome. Rodents are however absent from some arctic islands, and studies on performance of arctic predators under such circumstances may be very instructive since rodent cycles have been predicted to collapse in a warming Arctic. Here we document for the first time how three normally rodent-dependent predator species-rough-legged buzzard, arctic fox and red fox - perform in a low-arctic ecosystem with no rodents. During six years (in 2006-2008 and 2011-2013) we studied diet and breeding performance of these predators in the rodent-free Kolguev Island in Arctic Russia. The rough-legged buzzards, previously known to be a small rodent specialist, have only during the last two decades become established on Kolguev Island. The buzzards successfully breed on the island at stable low density, but with high productivity based on goslings and willow ptarmigan as their main prey - altogether representing a novel ecological situation for this species. Breeding density of arctic fox varied from year to year, but with stable productivity based on mainly geese as prey. The density dynamic of the arctic fox appeared to be correlated with the date of spring arrival of the geese. Red foxes breed regularly on the island but in very low numbers that appear to have been unchanged over a long period - a situation that resemble what has been recently documented from Arctic America. Our study suggests that the three predators found breeding on Kolguev Island possess capacities for shifting to changing circumstances in low-arctic ecosystem as long as other small - medium sized terrestrial herbivores are present in good numbers. PMID:25692786

  15. Rough-Legged Buzzards, Arctic Foxes and Red Foxes in a Tundra Ecosystem without Rodents

    PubMed Central

    Pokrovsky, Ivan; Ehrich, Dorothée; Ims, Rolf A.; Kondratyev, Alexander V.; Kruckenberg, Helmut; Kulikova, Olga; Mihnevich, Julia; Pokrovskaya, Liya; Shienok, Alexander

    2015-01-01

    Small rodents with multi-annual population cycles strongly influence the dynamics of food webs, and in particular predator-prey interactions, across most of the tundra biome. Rodents are however absent from some arctic islands, and studies on performance of arctic predators under such circumstances may be very instructive since rodent cycles have been predicted to collapse in a warming Arctic. Here we document for the first time how three normally rodent-dependent predator species—rough-legged buzzard, arctic fox and red fox – perform in a low-arctic ecosystem with no rodents. During six years (in 2006-2008 and 2011-2013) we studied diet and breeding performance of these predators in the rodent-free Kolguev Island in Arctic Russia. The rough-legged buzzards, previously known to be a small rodent specialist, have only during the last two decades become established on Kolguev Island. The buzzards successfully breed on the island at stable low density, but with high productivity based on goslings and willow ptarmigan as their main prey – altogether representing a novel ecological situation for this species. Breeding density of arctic fox varied from year to year, but with stable productivity based on mainly geese as prey. The density dynamic of the arctic fox appeared to be correlated with the date of spring arrival of the geese. Red foxes breed regularly on the island but in very low numbers that appear to have been unchanged over a long period – a situation that resemble what has been recently documented from Arctic America. Our study suggests that the three predators found breeding on Kolguev Island possess capacities for shifting to changing circumstances in low-arctic ecosystem as long as other small - medium sized terrestrial herbivores are present in good numbers. PMID:25692786

  16. Vector-borne pathogens in arctic foxes, Vulpes lagopus, from Canada.

    PubMed

    Mascarelli, Patricia E; Elmore, Stacey A; Jenkins, Emily J; Alisauskas, Ray T; Walsh, Mary; Breitschwerdt, Edward B; Maggi, Ricardo G

    2015-04-01

    Because of the relatively low biodiversity within arctic ecosystems, arctic foxes, Vulpes lagopus, could serve as sentinels for the study of changes in the ecology of vector-borne zoonotic pathogens. The objective of this study was to determine the molecular prevalence of 5 different genera of vector borne pathogens (Anaplasma, Babesia, Bartonella, Ehrlichia, and Hemotropic Mycoplasma spp.) using blood collected from 28 live-trapped arctic foxes from the region of Karrak Lake, Nunavut, Canada. Bartonella henselae (n = 3), Mycoplasma haemocanis (n = 1), Ehrlichia canis (n = 1), and an Anaplasma sp. (n = 1) DNA were PCR amplified and subsequently identified by sequencing. This study provides preliminary evidence that vector borne pathogens, not typically associated with the arctic ecosystem, exist at low levels in this arctic fox population, and that vector exposure, pathogen transmission dynamics, and changes in the geographic distribution of pathogens over time should be investigated in future studies. PMID:25596149

  17. CO2 rise amplified influence in the Arctic

    NASA Astrophysics Data System (ADS)

    Jakobson, Erko

    2016-04-01

    Kiehl and Trenberth estimated in their 1997 paper that the most important greenhouse gases are water vapour (60%) and CO2 (26%). Kiehl and Trenberth used vertical profiles of temperature, water vapour, and ozone that were derived from the U.S. Standard Atmosphere from 1976. Actual conditions in the Arctic differ significantly from this standard case. Integrated water vapour in the U.S. Standard Atmosphere is 14 mm, but the values in the Arctic are averagely below 4 mm in winter and even in summer averagely about 12 mm. As in the Arctic is less water vapour but CO2 is distributed quite evenly around the globe, then CO2 rise affects Arctic region climate warming more than in lower latitudes, especially in winter. In the presentation is planned to analyse together water vapour and CO2 absorption and scattering at different wavelengths. Main interest is to determine water vapour and CO2 proportional importance's as greenhouse gases at different Arctical humidity levels.

  18. Principal Component Analysis of Arctic Solar Irradiance Spectra

    NASA Technical Reports Server (NTRS)

    Rabbette, Maura; Pilewskie, Peter; Gore, Warren J. (Technical Monitor)

    2000-01-01

    During the FIRE (First ISCPP Regional Experiment) Arctic Cloud Experiment and coincident SHEBA (Surface Heat Budget of the Arctic Ocean) campaign, detailed moderate resolution solar spectral measurements were made to study the radiative energy budget of the coupled Arctic Ocean - Atmosphere system. The NASA Ames Solar Spectral Flux Radiometers (SSFRs) were deployed on the NASA ER-2 and at the SHEBA ice camp. Using the SSFRs we acquired continuous solar spectral irradiance (380-2200 nm) throughout the atmospheric column. Principal Component Analysis (PCA) was used to characterize the several tens of thousands of retrieved SSFR spectra and to determine the number of independent pieces of information that exist in the visible to near-infrared solar irradiance spectra. It was found in both the upwelling and downwelling cases that almost 100% of the spectral information (irradiance retrieved from 1820 wavelength channels) was contained in the first six extracted principal components. The majority of the variability in the Arctic downwelling solar irradiance spectra was explained by a few fundamental components including infrared absorption, scattering, water vapor and ozone. PCA analysis of the SSFR upwelling Arctic irradiance spectra successfully separated surface ice and snow reflection from overlying cloud into distinct components.

  19. Research Applications of Data from Arctic Ocean Drifting Platforms: The Arctic Buoy Program and the Environmental Working Group CD's.

    NASA Astrophysics Data System (ADS)

    Moritz, R. E.; Rigor, I.

    2006-12-01

    ABSTRACT: The Arctic Buoy Program was initiated in 1978 to measure surface air pressure, surface temperature and sea-ice motion in the Arctic Ocean, on the space and time scales of synoptic weather systems, and to make the data available for research, forecasting and operations. The program, subsequently renamed the International Arctic Buoy Programme (IABP), has endured and expanded over the past 28 years. A hallmark of the IABP is the production, dissemination and archival of research-quality datasets and analyses. These datasets have been used by the authors of over 500 papers on meteorolgy, sea-ice physics, oceanography, air-sea interactions, climate, remote sensing and other topics. Elements of the IABP are described briefly, including measurements, analysis, data dissemination and data archival. Selected highlights of the research applications are reviewed, including ice dynamics, ocean-ice modeling, low-frequency variability of Arctic air-sea-ice circulation, and recent changes in the age, thickness and extent of Arctic Sea-ice. The extended temporal coverage of the data disseminated on the Environmental Working Group CD's is important for interpreting results in the context of climate.

  20. Shrub expansion and climate feedbacks in Arctic tundra

    NASA Astrophysics Data System (ADS)

    Loranty, Michael M.; Goetz, Scott J.

    2012-03-01

    Arctic tundra ecosystems stand to play a substantial role in both the magnitude and rate of global climate warming over the coming decades and centuries. The exact nature of this role will be determined by the combined effects of currently amplified rates of climate warming in the Arctic (Serreze et al 2000) and a series of related positive climate feedbacks that include mobilization of permafrost carbon (Schuur et al 2008), decreases in surface albedo (Chapin et al 2005) and evapotranspiration (ET) mediated increases in atmospheric water vapor (Swann et al 2010). Conceptually, these feedback mechanisms are intuitive and readily comprehensible: warming-induced permafrost thaw will make new soil carbon pools accessible for microbial respiration, and increased vegetation productivity, expansion of shrubs in particular, will lower surface reflectance and increase ET. However, our current understanding of these feedback mechanisms relies largely on limited and local field studies and, as such, the quantitative estimates of feedback effects on regional and global climate require spatial upscaling and uncertainty estimates derived from models. Moreover, the feedback mechanisms interact and their combined net effect on climate is highly variable and not well characterized. A recent study by Bonfils et al (2012) is among the first to explicitly examine how shrub expansion in tundra ecosystems will impact regional climate. Using an Earth system model, Bonfils et al find that an idealized 20% increase in shrub cover north of 60°N latitude will lead to annual temperature increases of 0.66 °C and 1.84 °C, respectively, when the shrubs are 0.5 m and 2 m tall. The modeled temperature increases arise from atmospheric heating as a combined consequence of decreased albedo and increased ET. The primary difference between the two cases is associated with the fact that tall shrubs protrude above the snow, thus reducing albedo year round, whereas short shrubs are completely

  1. Permeability-thickness determination from transient production response at the southeast geysers

    SciTech Connect

    Faulder, D.D.

    1996-08-01

    The Fetkovich production decline curve analysis method was extended for application to vapor-dominated geothermal reservoirs for the purpose of estimating the permeability-thickness product (kh) from the transient production response. The analytic dimensionless terms for pressure, production rate, decline rate, and decline time were derived for saturated steam using the real gas potential and customary geothermal production units of pounds-mass per hour. The derived terms were numerically validating using ``Geysers-line`` reservoir properties at initial water saturation of 0 and at permeabilities of 1, 10, and 100 mD. The production data for 48 wells in the Southeast Geysers were analyzed and the permeability-thickness products determined from the transient production response using the Fetkovich production decline type curve. The kh results were in very good agreement with the published range at the Southeast Geysers and show regions of high permeability-thickness.

  2. Research on the seasonal snow of the Arctic Slope

    SciTech Connect

    Benson, C.S.

    1987-01-01

    This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R{sub 4}D project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

  3. Research on the seasonal snow of the Arctic Slope

    SciTech Connect

    Benson, C.S.

    1991-01-01

    This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R{sub 4}D project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

  4. Research on the seasonal snow of the Arctic Slope

    SciTech Connect

    Benson, C.S.

    1989-01-01

    This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R40 project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination Of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

  5. Research on the seasonal snow of the Arctic Slope

    SciTech Connect

    Benson, C.S.

    1986-01-01

    This project deals with the seasonal snow on Alaska's Arctic Slope. It is concentrated on snow of the R{sub 4}D project area. However, an important aspect of this study is to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

  6. Lidar for monitoring methane hydrate in the arctic permafrost

    NASA Astrophysics Data System (ADS)

    Grishkanich, A. S.; Bespalov, V. G.; Sidorov, I. S.; Gusarov, A. S.; Kascheev, S. V.; Elizarov, V. V.; Zhevlakov, A. P.

    2005-05-01

    Over the past 100 years, the rate of temperature in the Arctic increases almost twice higher than the average rate of warming of the planet. Identifying methane anomalies responsible for the temperature increase, by hiking trails in the Arctic requires great human labor. It is necessary to use lidar methods for search and identification of methane from permafrost. Necessary to create a Raman lidar for monitoring of emissions of methane hydrate from the permafrost. Hyperspectral resolution would resolve the isotope shifts in the Stokes spectra, thereby to determine the isotopic composition of methane ratio C14/C12 CH4 carbon emissions and identify the source for study (permafrost or oil deposits)

  7. Circumpolar Arctic vegetation: a hierarchic review and roadmap toward an internationally consistent approach to survey, archive and classify tundra plot data

    NASA Astrophysics Data System (ADS)

    Walker, D. A.; Daniëls, F. J. A.; Alsos, I.; Bhatt, U. S.; Breen, A. L.; Buchhorn, M.; Bültmann, H.; Druckenmiller, L. A.; Edwards, M. E.; Ehrich, D.; Epstein, H. E.; Gould, W. A.; Ims, R. A.; Meltofte, H.; Raynolds, M. K.; Sibik, J.; Talbot, S. S.; Webber, P. J.

    2016-05-01

    Satellite-derived remote-sensing products are providing a modern circumpolar perspective of Arctic vegetation and its changes, but this new view is dependent on a long heritage of ground-based observations in the Arctic. Several products of the Conservation of Arctic Flora and Fauna are key to our current understanding. We review aspects of the PanArctic Flora, the Circumpolar Arctic Vegetation Map, the Arctic Biodiversity Assessment, and the Arctic Vegetation Archive (AVA) as they relate to efforts to describe and map the vegetation, plant biomass, and biodiversity of the Arctic at circumpolar, regional, landscape and plot scales. Cornerstones for all these tools are ground-based plant-species and plant-community surveys. The AVA is in progress and will store plot-based vegetation observations in a public-accessible database for vegetation classification, modeling, diversity studies, and other applications. We present the current status of the Alaska Arctic Vegetation Archive (AVA-AK), as a regional example for the panarctic archive, and with a roadmap for a coordinated international approach to survey, archive and classify Arctic vegetation. We note the need for more consistent standards of plot-based observations, and make several recommendations to improve the linkage between plot-based observations biodiversity studies and satellite-based observations of Arctic vegetation.

  8. Determination of optimal lot size and production rate for multi-production channels with limited capacity

    NASA Astrophysics Data System (ADS)

    Huang, Yeu-Shiang; Wang, Ruei-Pei; Ho, Jyh-Wen

    2015-07-01

    Due to the constantly changing business environment, producers often have to deal with customers by adopting different procurement policies. That is, manufacturers confront not only predictable and regular orders, but also unpredictable and irregular orders. In this study, from the perspective of upstream manufacturers, both regular and irregular orders are considered in coping with the situation in which an uncertain demand is faced by the manufacturer, and a capacity confirming mechanism is used to examine such demand. If the demand is less than or equal to the capacity of the ordinary production channel, the general supply channel is utilised to fully account for the manufacturing process, but if the demand is greater than the capacity of the ordinary production channel, the contingency production channel would be activated along with the ordinary channel to satisfy the upcoming high demand. Besides, the reproductive property of the probability distribution is employed to represent the order quantity of the two types of demand. Accordingly, the optimal production rates and lot sizes for both channels are derived to provide managers with insights for further production planning.

  9. Improving the representation of Arctic photosynthesis in Earth System Models

    NASA Astrophysics Data System (ADS)

    Rogers, A.; Serbin, S.; Sloan, V. L.; Norby, R. J.; Wullschleger, S. D.

    2014-12-01

    The primary goal of Earth System Models (ESMs) is to improve understanding and projection of future global change. In order to do this models must accurately represent the terrestrial carbon cycle. Although Arctic carbon fluxes are small relative to global carbon fluxes, uncertainty is large. Photosynthetic CO2 uptake is well described by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis and most ESMs use a derivation of the FvCB model to calculate gross primary productivity. Two key parameters required by the FvCB model are an estimate of the maximum rate of carboxylation by the enzyme Rubisco (Vc,max) and the maximum rate of electron transport (Jmax). In ESMs the parameter Vc,max is typically fixed for a given plant functional type (PFT). Only four ESMs currently have an explicit Arctic PFT and the data used to derive Vc,max in these models relies on small data sets and unjustified assumptions. We examined the derivation of Vc,max and Jmax in current Arctic PFTs and estimated Vc,max and Jmax for a range of Arctic PFTs growing on the Barrow Environmental Observatory, Barrow, AK. We found that the values of Vc,max currently used to represent Arctic plants in ESMs are 70% lower than the values we measured, and contemporary temperature response functions for Vc,max also appear to underestimate Vc,max at low temperature. ESMs typically use a single multiplier (JVratio) to convert Vc,max to Jmax, however we found that the JVratio of Arctic plants is higher than current estimates suggesting that Arctic PFTs will be more responsive to rising carbon dioxide than currently projected. In addition we are exploring remotely sensed methods to scale up key biochemical (e.g. leaf N, leaf mass area) and physiological (e.g. Vc,max and Jmax) properties that drive model representation of photosynthesis in the Arctic. Our data suggest that the Arctic tundra has a much greater capacity for CO2 uptake, particularly at low temperature, and will be more CO2 responsive

  10. Processes Controlling Water Vapor in the Winter Arctic Stratospheric Middleworld

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Selkirk, Henry B.; Jensen, Eric J.; Podolske, James; Sachse, Glen; Avery, Melody; Schoeberl, Mark R.; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    Abstract: Water vapor in the winter arctic stratospheric middleworld (that part of the stratosphere with potential temperatures lower than the tropical tropopause) is important for two reasons: (1) the arctic middleworld is a source of air for the upper troposphere because of the generally downward motion, and thus its water vapor content helps determine upper tropospheric water, a critical part of the earth's radiation budget; and (2) under appropriate conditions, relative humidities will be large even to the point of stratospheric cirrus cloud formation, leading to the production of active chlorine species that could destroy ozone. On a number of occasions during SOLVE, clouds were observed in the stratospheric middleworld by the DC-8 aircraft. The relationship between ozone and CO from aircraft measurements taken during the early, middle and late part of the winter of 1999-2000 show that recent mixing with tropospheric air extends up to ozone values of about 350-450 ppbv. Above that level, the relationship suggests stratospheric air with minimal tropospheric influence. The transition is quite abrupt, particularly in early spring. Trajectory analyses are consistent with these relationships, with a significant drop-off in the percentage of trajectories with tropospheric PV values in their 10-day history as in-situ ozone increases above 400 ppbv. The water distribution is affected by these mixing characteristics, and by cloud formation. Significant cloud formation along trajectories occurs up to ozone values of about 400 ppbv during the early spring, with small, but nonzero probabilities extending to 550 ppbv. Cloud formation in the stratospheric middleworld is minimal during early and midwinter. Also important is the fact that, during early spring 30% of the trajectories near the tropopause (ozone values less than 200 ppbv) have minimum saturation mixing ratios less than 5 ppmv. Such parcels can mix out into the troposphere and could lead to very dry conditions in

  11. Arctic acoustics ultrasonic modeling studies

    NASA Astrophysics Data System (ADS)

    Chamuel, Jacques R.

    1990-03-01

    A unique collection of laboratory ultrasonic modeling results are presented revealing and characterizing hidden pulsed seismoacoustic wave phenomena from 3-D range dependent liquid/solid boundaries. The research succeeded in isolating and identifying low frequency (10 to 500 Hz) transmission loss mechanisms and provided physical insight into Arctic acoustic problems generally beyond the state-of-the-art of theoretical and numerical analysis. The ultrasonic modeling studies dealt with controversial issues and existing discrepancies on seismo-acoustic waves at water/ice interface, sea ice thickness determination, low frequency transmission loss, and bottom leaky Rayleigh waves. The areas investigated include leaky Rayleigh waves at water/ice interface, leaky flexural waves in floating ice plates, effects of dry/wet cracks in sea ice on plate waves and near grazing acoustic waves, edge waves in floating plates, low frequency backscatter from ice keel width resonances, conversion of underwater acoustic waves into plate waves by keels, nondispersive flexural wave along apex of small angle solid wedge, Scholte and leaky Rayleigh waves along apex of immersed 90 ice wedge, backscatter from trailing edge of floes, floating plate resonances associated with near-grazing underwater acoustic waves, acoustic coupling between adjacent floes, and multiple bottom leaky Rayleigh wave components in water layer over solid bottom.

  12. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Newell, J. P.; Schweiger, A.; Crane, R. G.

    1986-01-01

    A set of cloud cover data were developed for the Arctic during the climatically important spring/early summer transition months. Parallel with the determination of mean monthly cloud conditions, data for different synoptic pressure patterns were also composited as a means of evaluating the role of synoptic variability on Arctic cloud regimes. In order to carry out this analysis, a synoptic classification scheme was developed for the Arctic using an objective typing procedure. A second major objective was to analyze model output of pressure fields and cloud parameters from a control run of the Goddard Institue for Space Studies climate model for the same area and to intercompare the synoptic climatatology of the model with that based on the observational data.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Arctic palaeosalinities during late Cainozoic time

    USGS Publications Warehouse

    Herman, Y.; O'Neil, J.R.

    1975-01-01

    DURING the late Cainozoic, alternations between interglacial and glacial conditions, manifested by waning and waxing of continental ice sheets coincided with the rise and fall of seawater temperatures. Our palaeontological and oxygen isotope data indicate that although the major oceans and low latititude seas underwent large temperature variations, ??? 5-10 ??C, Arctic water temperatures remained near freezing point for at least the past 3 Myr, the time interval represented by the longest studied cores. We have determined palaeotemperatures from the ratio of left to right coiling Globigerina pachyderma1-3 and calculated palaeosalinities using the oxygen isotope palaeotemperature expression of Epstein et al.4. ?? 1975 Nature Publishing Group.

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

    USGS Publications Warehouse

    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 < 1%; SE < 1%) and snorkeling (mean = 1%; SE = 1%) surveys; Arctic grayling constituted 0–14% of the salmonid catch obtained by targeted angling (3 of 22 fish; mean = 4%; SE = 5%). Low values of the genetic differentiation index (F ST = 0.0021 ± 0.002 [mean ± 95% confidence interval]) between headwater lake and river Arctic grayling indicated that fish from throughout the Gibbon River system probably belonged to the same population. 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. The Arctic Observing Viewer: A Web-mapping Application for U.S. Arctic Observing Activities

    NASA Astrophysics Data System (ADS)

    Cody, R. P.; Manley, W. F.; Gaylord, A. G.; Kassin, A.; Villarreal, S.; Barba, M.; Dover, M.; Escarzaga, S. M.; Habermann, T.; Kozimor, J.; Score, R.; Tweedie, C. E.

    2015-12-01

    interoperable resources in this way will help to ensure improved capacities for conducting activities such as assessing the status of arctic observing efforts, optimizing logistic operations, and for quickly accessing external and project-focused web resources for more detailed information and access to scientific data and derived products.

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

    SciTech Connect

    Not Available

    1983-10-01

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

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

    SciTech Connect

    Sackinger, W. M.

    1980-08-01

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

  19. Arctic layer salinity controls heat loss from deep Atlantic layer in seasonally ice-covered areas of the Barents Sea

    NASA Astrophysics Data System (ADS)

    Lind, Sigrid; Ingvaldsen, Randi B.; Furevik, Tore

    2016-05-01

    In the seasonally ice-covered northern Barents Sea an intermediate layer of cold and relatively fresh Arctic Water at ~25-110 m depth isolates the sea surface and ice cover from a layer of warm and saline Atlantic Water below, a situation that resembles the cold halocline layer in the Eurasian Basin. The upward heat flux from the Atlantic layer is of major concern. What causes variations in the heat flux and how is the Arctic layer maintained? Using observations, we found that interannual variability in Arctic layer salinity determines the heat flux from the Atlantic layer through its control of stratification and vertical mixing. A relatively fresh Arctic layer effectively suppresses the upward heat flux, while a more saline Arctic layer enhances the heat flux. The corresponding upward salt flux causes a positive feedback. The Arctic layer salinity and the water column structures have been remarkably stable during 1970-2011.

  20. 77 FR 31677 - Request for Public Comment on Interagency Arctic Research Policy Committee (IARPC) Arctic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... contiguous seas, including the Arctic Ocean and the Beaufort, Bering, and Chukchi Seas; and the Aleutian... TECHNOLOGY POLICY Request for Public Comment on Interagency Arctic Research Policy Committee (IARPC) Arctic Research Plan: FY2013-2017 May 22, 2012. ACTION: Request for public comment. SUMMARY: The Arctic...

  1. 78 FR 21977 - Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ...,049, 77 FR 2087 (Jan. 13, 2012). The respondents are Analog Devices Inc. of Norwood, Massachusetts... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination...

  2. Determination of Vapor Pressure-Temperature Relationships of Current Use Pesticides and Transformation Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sub-cooled liquid vapor pressures of current use organochlorine and organophosphate pesticides (chlorothalonil, chlorpyrifos methyl, diazinon, fipronil) and selected transformation products (chlorpyrifos oxon, heptachlor epoxide, oxychlordane, 3,5,6-trichloro-2-pyridinol) were determined at multiple...

  3. 78 FR 79638 - Energy Conservation Program for Consumer Products: Proposed Determination of Hearth Products as a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-31

    ... energy conservation standards for vented gas hearth products. 75 FR 20112. Following DOE's adoption of... rule and an amendment to that rule published on November 18, 2011 (76 FR 71836) as those rules... at: http://www.regulations.gov/#%21docketDetail...

  4. Modelling tundra vegetation response to recent arctic warming.

    PubMed

    Miller, Paul A; Smith, Benjamin

    2012-01-01

    The Arctic land area has warmed by > 1 °C in the last 30 years and there is evidence that this has led to increased productivity and stature of tundra vegetation and reduced albedo, effecting a positive (amplifying) feedback to climate warming. We applied an individual-based dynamic vegetation model over the Arctic forced by observed climate and atmospheric CO(2) for 1980-2006. Averaged over the study area, the model simulated increases in primary production and leaf area index, and an increasing representation of shrubs and trees in vegetation. The main underlying mechanism was a warming-driven increase in growing season length, enhancing the production of shrubs and trees to the detriment of shaded ground-level vegetation. The simulated vegetation changes were estimated to correspond to a 1.75 % decline in snow-season albedo. Implications for modelling future climate impacts on Arctic ecosystems and for the incorporation of biogeophysical feedback mechanisms in Arctic system models are discussed. PMID:22864701

  5. Methylmercury cycling in High Arctic wetland ponds: sources and sinks.

    PubMed

    Lehnherr, Igor; St Louis, Vincent L; Emmerton, Craig A; Barker, Joel D; Kirk, Jane L

    2012-10-01

    The sources of methylmercury (MeHg; the toxic form of mercury that is biomagnified through foodwebs) to Arctic freshwater organisms have not been clearly identified. We used a mass balance approach to quantify MeHg production in two wetland ponds in the Lake Hazen region of northern Ellesmere Island, NU, in the Canadian High Arctic and to evaluate the importance of these systems as sources of MeHg to Arctic foodwebs. We show that internal production (1.8-40 ng MeHg m(-2) d(-1)) is a much larger source of MeHg than external inputs from direct atmospheric deposition (0.029-0.051 ng MeHg m(-2) d(-1)), as expected. Furthermore, MeHg cycling in these systems is dominated by Hg(II) methylation and MeHg photodemethylation (2.0-33 ng MeHg m(-2) d(-1)), which is a sink for a large proportion of the MeHg produced by Hg(II) methylation in these ponds. We also show that MeHg production in the two study ponds is comparable to what has previously been measured in numerous more southerly systems known to be important MeHg sources, such as temperate wetlands and lakes, demonstrating that wetland ponds in the High Arctic are important sources of MeHg to local aquatic foodwebs. PMID:22779785

  6. Moderate-resolution sea surface temperature data for the Arctic Ocean Ecoregions

    EPA Science Inventory

    Sea surface temperature (SST) is an important environmental characteristic in determining the suitability and sustainability of habitats for marine organisms. Of particular interest is the fate of the Arctic Ocean, which provides critical habitat to commercially important fish (M...

  7. The Arctic-Boreal Vulnerability Experiment: a NASA Terrestrial Ecology Field Campaign

    NASA Astrophysics Data System (ADS)

    Griffith, P. C.; Goetz, S. J.; Kasischke, E. S.; Mack, M. C.; Wickland, D. E.

    2012-12-01

    Climate change in the Arctic and Boreal Region (ABR) is unfolding faster than anywhere else on Earth, resulting in receding glaciers, a longer ice-free Arctic Ocean during summer, warming and thawing of permafrost, increases in the frequency and severity of climate-driven disturbances, and widespread changes to surface water extent and vegetation structure and function. To more fully understand the evolving ABR environment and provide the information required to develop options for societal responses to the impacts of ABR climate change, the Arctic-Boreal Vulnerability Experiment (ABoVE) has been proposed as a NASA Terrestrial Ecology Program field campaign. Remotely-sensed data products would be created to address scaling issues that are inherent in linking process-based research conducted at local scales over short time periods to modeling research that addresses a variety of spatial and temporal scales. Research carried out as part of ABoVE would provide the opportunity to not only focus on key process associated with the land surface, but on key interfaces between the land and the coastal ocean and atmospheric boundary layer as they interact with climate-mediated terrestrial processes. Proposed Scientific Scope: 1. What processes, interactions, and feedbacks control the vulnerability of Arctic and boreal ecosystems and landscapes to structural and functional changes in a changing Earth system? 2. How are people at local, regional, national, and global scales being affected by and responding to these changes? 3. How do changes to terrestrial processes in the ABR alter inputs to the adjacent ocean? 4. How do changes to terrestrial processes in the ABR provide feedbacks to regional and global climate through exchanges of energy, water, gases, and particulate matter between the land surface and troposphere? A NASA-sponsored workshop to further develop and evaluate the scientific scope for the Arctic-Boreal Vulnerability Experiment (ABoVE) was held in Boulder, CO

  8. Sea ice forces and the state of technology of offshore arctic platforms

    SciTech Connect

    Utt, M.E.

    1985-01-01

    Hydrocarbon exploration and production operations in offshore arctic regions are in their infancy. The oil industry learned to operate in ice conditions in the relatively mild environment of Cook Inlet in the 1960's and in the Arctic offshore Canada in the 1970's. Presently, there is no production from the offshore Arctic, only a handful of exploration systems with the capability of operating year-round in shallow water; there are no year-round systems for deeper water. As drilling and production activities are extended into deeper water and more hostile ice conditions, the industry will learn more about the Arctic, and some of the opinions expressed in this paper will, no doubt, become of no more than historical interest.

  9. AMSR2 Daily Arctic Sea Ice - 2014

    NASA Video Gallery

    In this animation, the daily Arctic sea ice and seasonal land cover change progress through time, from March 21, 2014 through the 3rd of August, 2014. Over the water, Arctic sea ice changes from da...

  10. Arctic Sea Ice Changes 2011-2012

    NASA Video Gallery

    Animation showing changes in monthly Arctic sea ice volume using data from ESA's CryoSat-2 (red dots) and estimates from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) (solid li...

  11. Time varying arctic climate change amplification

    SciTech Connect

    Chylek, Petr; Dubey, Manvendra K; Lesins, Glen; Wang, Muyin

    2009-01-01

    During the past 130 years the global mean surface air temperature has risen by about 0.75 K. Due to feedbacks -- including the snow/ice albedo feedback -- the warming in the Arctic is expected to proceed at a faster rate than the global average. Climate model simulations suggest that this Arctic amplification produces warming that is two to three times larger than the global mean. Understanding the Arctic amplification is essential for projections of future Arctic climate including sea ice extent and melting of the Greenland ice sheet. We use the temperature records from the Arctic stations to show that (a) the Arctic amplification is larger at latitudes above 700 N compared to those within 64-70oN belt, and that, surprisingly; (b) the ratio of the Arctic to global rate of temperature change is not constant but varies on the decadal timescale. This time dependence will affect future projections of climate changes in the Arctic.

  12. 78 FR 44158 - Notice of Final Determination Revising the List of Products Requiring Federal Contractor...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ...This final determination is the fourth revision of the list required by Executive Order 13126 (``Prohibition of Acquisition of Products Produced by Forced or Indentured Child Labor''), in accordance with the ``Procedural Guidelines for the Maintenance of the List of Products Requiring Federal Contractor Certification as to Forced or Indentured Child Labor Under 48 CFR Subpart 22.15 and E.O.......

  13. 78 FR 77714 - Certain Laundry and Household Cleaning Products and Related Packaging Commission Determination...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-24

    ... The Clorox Company of Oakland, California (``Clorox''). 78 FR 53479 (Aug. 29, 2013). The complaint... COMMISSION Certain Laundry and Household Cleaning Products and Related Packaging Commission Determination Not... importation of certain laundry and household cleaning products and packaging thereof by reason of...

  14. 77 FR 31876 - Certain Consumer Electronics and Display Devices and Products Containing Same Determination Not...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-30

    ... Properties Holdings, Inc. of New Rochelle, New York (``GPH''). 77 FR 21584 (April 10, 2012). The complaint... COMMISSION Certain Consumer Electronics and Display Devices and Products Containing Same Determination Not To... importation of certain consumer electronics and display devices and products containing the same by reason...

  15. 77 FR 27085 - TMI Forest Products, Inc., Crane Creek Division, Morton, WA; Notice of Negative Determination...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-08

    ... Determination was published in the Federal Register on March 6, 2012 (77 FR 13355). Pursuant to 29 CFR 90.18(c... Employment and Training Administration TMI Forest Products, Inc., Crane Creek Division, Morton, WA; Notice of... (TAA), applicable to workers and former workers of TMI Forest Products, Inc., Crane Creek...

  16. Arctic Sea Ice Changes, Interactions, and Feedbacks on the Arctic Climate during the Satellite Era

    NASA Astrophysics Data System (ADS)

    Wang, X.; Key, J. R.; Liu, Y.

    2011-12-01

    the shortcomings of current climate models in the projections of future climate change and feedback mechanisms at high latitudes. Interactions and feedbacks between clouds, sea ice, and various atmospheric circulation patterns in the Arctic are also investigated based on multi-decadal satellite products, including cloud characteristics and radiation fluxes from the MODerate resolution Imaging Spectroradiometer (MODIS) data and the APP-x dataset, sea ice products from Special Sensor Microwave/Imager (SSM/I), and various atmospheric parameters from reanalysis data sets. Results demonstrate that changes in sea ice concentration and cloud cover played major roles in the magnitude of recent Arctic surface temperature trends. Interactions between sea ice and clouds are strong, such that recent shrinking of sea ice extent might influence future cloud cover changes. Not surprisingly, cloud cover is also affected by changes in large-scale atmospheric circulation patterns. Quantitative analyses of the relationships between trends in these parameters provide new insight into polar climates.

  17. Decreased albedo, e-folding depth and photolytic OH radical and NO2 production with increasing black carbon content in Arctic snow

    NASA Astrophysics Data System (ADS)

    Reay, H. J.; France, J. L.; King, M. D.

    2012-07-01

    The contribution of snow photochemistry to snow and atmospheric oxidative capacity is controlled, in part, by snow albedo and e-folding depths in snow. Albedo ande-folding depths (and thus snow photochemistry) are a function of black carbon concentration in snow. The paper presented here demonstrates the complicated response of albedo, e-folding depth (wavelengths 300-600 nm) and depth-integrated production rates of NO2and OH radicals to increasing black carbon concentration in well-characterized snowpacks of the Barrow OASIS campaign, Alaska. All snowpacks were reworked layered windpacks and were found to have similar responses to changes in black carbon concentration. The radiative-transfer calculations demonstrate two light absorption regimes: ice-dominated and black carbon dominated. The ice-dominated and black carbon dominated behavior of albedo,e-folding depth and depth-integrated production rates with increasing black carbon concentrations are presented. For black carbon concentrations greater than 20 ng g-1 (wavelength range of 300-600 nm), e-folding depth and depth-integrated production rate have an inverse power law relationship with black carbon concentration. Doubling the black carbon concentration decreases thee-folding depth to ˜70% of the initial value and for solar zenith angles greater than 60°, doubling the black carbon concentration decreases depth-integrated production rates of NO2 and OH to ˜70% and ˜65% of their original values respectively.

  18. Shifting patterns of life in the Pacific Arctic and sub-Arctic seas.

    PubMed

    Grebmeier, Jacqueline M

    2012-01-01

    Recent changes in the timing of sea ice formation and retreat, along with increasing seawater temperatures, are driving shifts in marine species composition that may signal marine ecosystem reorganization in the Pacific Arctic sector. Interannual variability in seasonal sea ice retreat in the northern Bering Sea has been observed over the past decade; north of the Bering Strait, the Chukchi Sea ecosystem has had consistent earlier spring sea ice retreat and later fall sea ice formation. The latitudinal gradient in sea ice persistence, water column chlorophyll, and carbon export to the sediments has a direct impact on ecosystem structure in this Arctic/sub-Arctic complex. Large-scale decadal patterns in the benthic biological system are driven by sea ice extent, hydrographic forcing, and export production that influences benthic processes. Shifts in species composition and northward faunal range expansions indicate a changing system. The shifting patterns of life and change in key biological processes have the potential for a system-wide reorganization of the marine ecosystem. PMID:22457969

  19. Influence of Sea Ice on Arctic Marine Sulfur Biogeochemistry in the Community Climate System Model

    SciTech Connect

    Deal, Clara; Jin, Meibing

    2013-06-30

    Global climate models (GCMs) have not effectively considered how responses of arctic marine ecosystems to a warming climate will influence the global climate system. A key response of arctic marine ecosystems that may substantially influence energy exchange in the Arctic is a change in dimethylsulfide (DMS) emissions, because DMS emissions influence cloud albedo. This response is closely tied to sea ice through its impacts on marine ecosystem carbon and sulfur cycling, and the ice-albedo feedback implicated in accelerated arctic warming. To reduce the uncertainty in predictions from coupled climate simulations, important model components of the climate system, such as feedbacks between arctic marine biogeochemistry and climate, need to be reasonably and realistically modeled. This research first involved model development to improve the representation of marine sulfur biogeochemistry simulations to understand/diagnose the control of sea-ice-related processes on the variability of DMS dynamics. This study will help build GCM predictions that quantify the relative current and possible future influences of arctic marine ecosystems on the global climate system. Our overall research objective was to improve arctic marine biogeochemistry in the Community Climate System Model (CCSM, now CESM). Working closely with the Climate Ocean Sea Ice Model (COSIM) team at Los Alamos National Laboratory (LANL), we added 1 sea-ice algae and arctic DMS production and related biogeochemistry to the global Parallel Ocean Program model (POP) coupled to the LANL sea ice model (CICE). Both CICE and POP are core components of CESM. Our specific research objectives were: 1) Develop a state-of-the-art ice-ocean DMS model for application in climate models, using observations to constrain the most crucial parameters; 2) Improve the global marine sulfur model used in CESM by including DMS biogeochemistry in the Arctic; and 3) Assess how sea ice influences DMS dynamics in the arctic marine

  20. The role of sustained observations and data co-management in Arctic Ocean governance

    NASA Astrophysics Data System (ADS)

    Eicken, H.; Lee, O. A.; Rupp, S. T.; Trainor, S.; Walsh, J. E.

    2015-12-01

    Rapid environmental change, a rise in maritime activities and resource development, and increasing engagement by non-Arctic nations are key to major shifts underway in Arctic social-environmental systems (SES). These shifts are triggering responses by policy makers, regulators and a range of other actors in the Arctic Ocean region. Arctic science can play an important role in informing such responses, in particular by (i) providing data from sustained observations to serve as indicators of change and major transitions and to inform regulatory and policy response; (ii) identifying linkages across subsystems of Arctic SES and across regions; (iii) providing predictions or scenarios of future states of Arctic SES; and (iv) informing adaptation action in response to rapid change. Policy responses to a changing Arctic are taking a multi-faceted approach by advancing international agreements through the Arctic Council (e.g., Search and Rescue Agreement), global forums (e.g., IMO Polar Code) or private sector instruments (e.g., ISO code for offshore structures). At the regional level, co-management of marine living resources involving local, indigenous stakeholders has proven effective. All of these approaches rely on scientific data and information for planning and decision-making. Examples from the Pacific Arctic sector illustrate how such relevant data is currently collected through a multitude of different government agencies, universities, and private entities. Its effective use in informing policy, planning and emergency response requires coordinated, sustained acquisition, common standards or best practices, and data sharing agreements - best achieved through data co-management approaches. For projections and scenarios of future states of Arctic SES, knowledge co-production that involves all relevant stakeholders and specifically addresses major sources of uncertainty is of particular relevance in an international context.

  1. Carbon cycle uncertainty in the Alaskan Arctic

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Sikka, M.; Oechel, W. C.; Huntzinger, D. N.; Melton, J. R.; Koven, C. D.; Ahlström, A.; Arain, A. M.; Baker, I.; Chen, J. M.; Ciais, P.; Davidson, C.; Dietze, M.; El-Masri, B.; Hayes, D.; Huntingford, C.; Jain, A.; Levy, P. E.; Lomas, M. R.; Poulter, B.; Price, D.; Sahoo, A. K.; Schaefer, K.; Tian, H.; Tomelleri, E.; Verbeeck, H.; Viovy, N.; Wania, R.; Zeng, N.; Miller, C. E.

    2014-02-01

    Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for Alaska, we provide a baseline of terrestrial carbon cycle structural and parametric uncertainty, defined as the multi-model standard deviation (σ) against the mean (x\\bar) for each quantity. Mean annual uncertainty (σ/x\\bar) was largest for net ecosystem exchange (NEE) (-0.01± 0.19 kg C m-2 yr-1), then net primary production (NPP) (0.14 ± 0.33 kg C m-2 yr-1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m-2 yr-1), gross primary production (GPP) (0.22 ± 0.50 kg C m-2 yr-1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m-2 yr-1), CH4 flux (2.52 ± 4.02 g CH4 m-2 yr-1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m-2 yr-1), and soil carbon (14.0± 9.2 kg C m-2). The spatial patterns in regional carbon stocks and fluxes varied widely with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Additionally, a feedback (i.e., sensitivity) analysis was conducted of 20th century NEE to CO2 fertilization (β) and climate (γ), which showed that uncertainty in γ was 2x larger than that of β, with neither indicating that the Alaskan Arctic is shifting towards a certain net carbon sink or source. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic.

  2. 78 FR 38053 - Determination That OPANA ER (Oxymorphone Hydrochloride) Drug Products Covered by New Drug...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-25

    ...The Food and Drug Administration (FDA) has determined that OPANA ER (oxymorphone hydrochloride (HCl)) Extended-Release Tablet products approved under new drug application (NDA) 21-610 were not withdrawn from sale for reasons of safety or effectiveness. This determination means that FDA will not begin procedures to withdraw approval of abbreviated new drug applications (ANDAs) that refer to......

  3. Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River Delta

    NASA Astrophysics Data System (ADS)

    Langer, M.; Westermann, S.; Anthony, K. M. Walter; Wischnewski, K.; Boike, J.

    2014-07-01

    Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO2 and methane CH4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO2 and CH4 emissions of tundra ecosystems. Waterbodies also have a marked effect on the thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition. This study presents net CH4 production rates during the freezing period from ponds within a typical lowland tundra landscape in northern Siberia. Rate estimations were based on CH4 concentrations measured in surface lake ice from a variety of waterbody types. Vertical profiles along ice blocks showed an exponential increase in CH4 concentration with depth. These CH4 profiles were reproduced by a 1-D mass balance model and the net CH4 production rates then inferred through inverse modeling. Results revealed marked differences in early winter net CH4 production among various ponds. Initial state ponds underlain by stable permafrost with little or no signs of degradation yielded low net production rates, of the order of 10-11 to 10-10 mol m-2 s-1 (0.01 to 0.14 mgCH4 m-2 d-1). In contrast, advanced state ponds exhibiting clear signs of thermal erosion yielded net CH4 production rates of the order of 10-7 mol m-2 s-1 (140 mgCH4 m-2 d-1). The net production rate per square meter of advanced state ponds exceeded the maximum summer CH4 emission rates per square meter which was measured for the average tundra landscape at the study site. Our results therefore indicate that, once a particular threshold in

  4. Climate science: A great Arctic ice shelf

    NASA Astrophysics Data System (ADS)

    Domack, Eugene

    2016-02-01

    Newly mapped features on the floor of the Arctic Ocean suggest that the Arctic basin was once covered by a one-kilometre-thick, flowing ice shelf derived from large ice sheets in eastern Siberia, Arctic Canada and the Barents Sea.

  5. The Arctic freshwater cycle during a naturally and an anthropogenically induced warm climate

    NASA Astrophysics Data System (ADS)

    Davies, Frazer J.; Renssen, Hans; Goosse, Hugues

    2014-04-01

    The Arctic freshwater cycle plays an important role in regulating regional and global climate. Current observations suggest that an intensification of the high-northern latitude hydrological cycle has caused a freshening of the Arctic and sub-Arctic seas, increasing the potential of weakening overturning strength in the Nordic seas, and reducing temperatures. It is not known if this freshening is a manifestation of the current anthropogenic warming and if the Arctic freshwater cycle has exhibited similar changes in the past, in particular as a response to naturally induced periods of warming, for example during the mid-Holocene hypsithermal. Thus, we have used an earth model of intermediate complexity, LOVECLIM, to investigate the response of the Arctic freshwater cycle, during two warm periods that evolved under different sets of forcings, the mid-Holocene and the twenty-first century. A combination of proxy reconstructions and modelling studies have shown these two periods to exhibit similar surface temperature anomalies, compared to the pre-industrial period, however, it has yet to be determined if the Arctic freshwater cycle and thus, the transport and redistribution of freshwater to the Arctic and the sub-Arctic seas, during these two warm periods, is comparable. Here we provide an overview that shows that the response of the Arctic freshwater cycle during the first half of the twenty-first century can be interpreted as an `extreme' mid-Holocene hydrological cycle. Whilst for the remainder of the twenty-first century, the Arctic freshwater cycle and the majority of its components will likely transition into what can only be described as truly anthropogenic in nature.

  6. Arctic contamination poses potential danger

    NASA Astrophysics Data System (ADS)

    Bush, Susan

    Following the dissolution of the former Soviet Union, some studies have been focused on the impact of radioactive and hazardous materials released into the Arctic environment, including air, water, and ground. Contamination from radionuclides, trace metals, and hydrocarbons has been examined. Speaking at the 73rd meeting of the National Research Council's Polar Research Board held June 28 in Washington, D.C., Lou Codispoti, Office of Naval Research, said that scientists have found that there is no immediate regional concern relating to this contamination, although the potential for future concern exists.Bruce Molnia, chief of polar programs at the U.S. Geological Survey, reported on a workshop on Arctic contamination that was held in Anchorage, Alaska, from May 2-7. The workshop was organized by the U.S. Interagency Arctic Research Policy Committee (IARPC), which is made up of fourteen federal agencies that conduct research in the Arctic, in response to Frank Murkowski (R-Alaska) asking what federal agencies would do about contamination in the Arctic. IARPC developed an “agenda for action,” which included the Anchorage workshop.

  7. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part II: Liquid freshwater

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Ilicak, Mehmet; Gerdes, Rüdiger; Drange, Helge; Aksenov, Yevgeny; Bailey, David A.; Bentsen, Mats; Biastoch, Arne; Bozec, Alexandra; Böning, Claus; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Curry, Beth; Danabasoglu, Gokhan; Danilov, Sergey; Fernandez, Elodie; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Iovino, Doroteaciro; Jahn, Alexandra; Jung, Thomas; Large, William G.; Lee, Craig; Lique, Camille; Lu, Jianhua; Masina, Simona; Nurser, A. J. George; Rabe, Benjamin; Roth, Christina; Salas y Mélia, David; Samuels, Bonita L.; Spence, Paul; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Xuezhu; Yeager, Steve G.

    2016-03-01

    The Arctic Ocean simulated in 14 global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the gateways where the ocean volume transport determines the FW transport variability. The variation of liquid FWC is induced by both the surface FW flux (associated with sea ice production) and lateral liquid FW transport, which are in phase when averaged on decadal time scales. The liquid FWC shows an increase starting from the mid-1990s, caused by the reduction of both sea ice formation and liquid FW export, with the former being more significant in most of the models. The mean state of the FW budget is less consistently simulated than the temporal variability. The model ensemble means of liquid FW transport through the Arctic gateways compare well with observations. On average, the models have too high mean FWC, weaker upward trends of FWC in the recent decade than the observation, and low consistency in the temporal variation of FWC spatial distribution, which needs to be further explored for the purpose of model development.

  8. Arctic hydrology and meteorology

    SciTech Connect

    Kane, D.L.

    1988-01-01

    The behavior of arctic ecosystems is directly related to the ongoing physical processes of heat and mass transfer. Furthermore, this system undergoes very large fluctuations in the surface energy balance. The buffering effect of both snow and the surface organic soils can be seen by looking at the surface and 40 cm soil temperatures. The active layer, that surface zone above the permafrost table, is either continually freezing or thawing. A large percentage of energy into and out of a watershed must pass through this thin veneer that we call the active layer. Likewise, most water entering and leaving the watershed does so through the active layer. To date, we have been very successful at monitoring the hydrology of Imnavait Creek with special emphasis on the active layer processes. The major contribution of this study is that year-round hydrologic data are being collected. An original objective of our study was to define how the thermal and moisture regimes within the active layer change during an annual cycle under natural conditions, and then to define how the regime will be impacted by some imposed terrain alteration. Our major analysis of the hydrologic data sets for Imnavait Creek have been water balance evaluations for plots during snowmelt, water balance for the watershed during both rainfall and snowmelt, and the application of a hydrologic model to predict the Imnavait Creek runoff events generated by both snowmelt and rainfall.

  9. Arctic hydrology and meteorology

    SciTech Connect

    Kane, D.L.

    1989-01-01

    To date, five years of hydrologic and meteorologic data have been collected at Imnavait Creek near Toolik Lake, Alaska. This is the most complete set of field data of this type collected in the Arctic of North America. These data have been used in process-oriented research to increase our understanding of atmosphere/hydrosphere/biosphere/lithosphere interactions. Basically, we are monitoring heat and mass transfer between various spheres to quantify rates. These could be rates of mass movement such as hillslope flow or rates of heat transfer for active layer thawing or combined heat and mass processes such as evapotranspiration. We have utilized a conceptual model to predict hydrologic processes. To test the success of this model, we are comparing our predicted rates of runoff and snowmelt to measured valves. We have also used a surface energy model to simulate active layer temperatures. The final step in this modeling effort to date was to predict what impact climatic warming would have on active layer thicknesses and how this will influence the hydrology of our research watershed by examining several streambeds.

  10. Arctic Landscape Within Reach

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image, one of the first captured by NASA's Phoenix Mars Lander, shows flat ground strewn with tiny pebbles and marked by small-scale polygonal cracking, a pattern seen widely in Martian high latitudes and also observed in permafrost terrains on Earth. The polygonal cracking is believed to have resulted from seasonal contraction and expansion of surface ice.

    Phoenix touched down on the Red Planet at 4:53 p.m. Pacific Time (7:53 p.m. Eastern Time), May 25, 2008, in an arctic region called Vastitas Borealis, at 68 degrees north latitude, 234 degrees east longitude.

    This image was acquired at the Phoenix landing site by the Surface Stereo Imager on day 1 of the mission on the surface of Mars, or Sol 0, after the May 25, 2008, landing.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  11. Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

    NASA Astrophysics Data System (ADS)

    Langer, M.; Westermann, S.; Anthony, K. Walter; Wischnewski, K.; Boike, J.

    2015-02-01

    Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO2 and methane CH4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO2 and CH4emissions of tundra ecosystems. Waterbodies also have a marked effect on the thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition. This study presents net CH4 production rates during the freezing period from ponds within a typical lowland tundra landscape in northern Siberia. Rate estimations were based on CH4 concentrations measured in surface lake ice from a variety of waterbody types. Vertical profiles along ice blocks showed an exponential increase in CH4 concentration with depth. These CH4 profiles were reproduced by a 1-D mass balance model and the net CH4 production rates were then inferred through inverse modeling. Results revealed marked differences in early winter net CH4 production among various ponds. Ponds situated within intact polygonal ground structures yielded low net production rates, of the order of 10-11 to 10-10 mol m-2 s-1 (0.01 to 0.14 mgCH4 m-2 day-1). In contrast, ponds exhibiting clear signs of erosion yielded net CH4 production rates of the order of 10-7 mol m-2 s-1 (140 mg CH4 m-2 day-1). Our results therefore indicate that once a particular threshold in thermal erosion has been crossed, ponds can develop into major CH4 sources. This implies that any future warming of the climate may result in nonlinear CH4 emission behavior in tundra ecosystems.

  12. Enabling Arctic Research Through Science and Engineering Partnerships

    NASA Astrophysics Data System (ADS)

    Kendall, E. A.; Valentic, T. A.; Stehle, R. H.

    2014-12-01

    Under an Arctic Research Support and Logistics contract from NSF (GEO/PLR), SRI International, as part of the CH2M HILL Polar Services (CPS) program, forms partnerships with Arctic research teams to provide data transfer, remote operations, and safety/operations communications. This teamwork is integral to the success of real-time science results and often allows for unmanned operations which are both cost-effective and safer. The CPS program utilizes a variety of communications networks, services and technologies to support researchers and instruments throughout the Arctic, including Iridium, VSAT, Inmarsat BGAN, HughesNet, TeleGreenland, radios, and personal locator beacons. Program-wide IT and communications limitations are due to the broad categories of bandwidth, availability, and power. At these sites it is essential to conserve bandwidth and power through using efficient software, coding and scheduling techniques. There are interesting new products and services on the horizon that the program may be able to take advantage of in the future such as Iridium NEXT, Inmarsat Xpress, and Omnispace mobile satellite services. Additionally, there are engineering and computer software opportunities to develop more efficient products. We will present an overview of science/engineering partnerships formed by the CPS program, discuss current limitations and identify future technological possibilities that could further advance Arctic science goals.

  13. Archaea in Arctic Thermokarst Lake Sediments

    NASA Astrophysics Data System (ADS)

    Matheus Carnevali, P. B.; Rohrssen, M.; Dodsworth, J. A.; Kuhn, E.; Williams, M.; Adams, H. E.; Berisford, D. F.; Hand, K. P.; Priscu, J. C.; Walter Anthony, K.; Love, G. D.; Hedlund, B. P.; Murray, A. E.

    2011-12-01

    Thermokarst lakes in the Northern Slope of Alaska are known to emit ebullient methane (CH4), some of which is of biogenic origin. Thawing of permafrost in the margins and bottom of these lakes, as a result of climate change, releases sources of carbon that could be used by methanogenic Archaea. However, the composition of Archaea inhabiting these lakes is not known. We have chosen a subset of Thermokarst lakes near Barrow Alaska to determine if there are methanogenic and methane oxidizing Archaea in these lake sediments. To describe the diversity of the archaeal community in the sediments we profiled the variable 3 (v3) region of the 16S rRNA gene of Archaea. The v3 profiles indicated surprisingly high levels of diversity, with 20 to 36 bands in the 10 sample horizons over the upper 100 cm of sediments surveyed in four lakes, at two times of the year. One of v3 rRNA gene bands was common to all lakes, and most phylotypes were grouped by depth (1-40 cm or 41-105 cm) within a lake. Likewise, cluster analysis indicated partitioning of archaeal communities between lakes. To specifically detect methanogens and anaerobic methanotrophs (ANME) in the sediments, DNA was surveyed by PCR to detect the methyl coenzyme M reductase (mcrA) gene, which is specific to the pathways of methanogenesis and anaerobic methane oxidation (AMO). An array of methanogen enrichment cultures was also set up. The expected 464-491 bp amplification product predicted for the mcrA gene was detected in all sediment samples. Assays of enrichment cultures incubated at 2 and 10 °C with substrates used in the main pathways for methanogenesis have produced positive growth and CH4 production results. Most cultures produced CH4 from carbon dioxide (CO2) reduction with hydrogen (H2), although methanol and acetate were also utilized as methanogenic substrates by a few cultures. From the experiments conducted to date we conclude that there is a great diversity of Archaea inhabiting these Thermokarst lakes

  14. Determination of prostaglandin analogs in cosmetic products by high performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Wittenberg, James B; Zhou, Wanlong; Wang, Perry G; Krynitsky, Alexander J

    2014-09-12

    A method was developed and validated for the determination of 16 prostaglandin analogs in cosmetic products. The QuEChERS (Quick, Easy, Cheap, Efficient, Rugged, Safe) liquid-liquid extraction method, typically used for pesticide residue analysis, was utilized as the sample preparation technique. The prostaglandin analogs were chromatographically separated and quantified using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Thirty-one cosmetic products were surveyed, and 13 products were determined to contain a prostaglandin analog with amounts ranging from 27.4 to 297μg/g. The calculated concentrations for the cosmetic products were in a similar range when compared to the concentrations of three different prostaglandin analog-containing prescription products. PMID:25085824

  15. Modeling the Response of Arctic Vegetation to Increasing Atmospheric Carbon Dioxide and Climate Change

    NASA Astrophysics Data System (ADS)

    Cassidy, E. S.; Snyder, P. K.

    2009-12-01

    An increase in atmospheric carbon dioxide is contributing to planetary warming that is strongest over high latitude land areas of the Northern Hemisphere. Elevated levels of atmospheric carbon dioxide and strong warming have led to changes in vegetation distribution, permafrost depth, and snow cover, which significantly affect the interactions between the terrestrial ecosystem and the climate through biophysical and biogeochemical processes. With a continued rise in greenhouse gas emissions and additional warming in the high latitudes, uncertainty exists as to how the Arctic biosphere will respond in the coming decades and whether Arctic ecosystems will remain a carbon sink or instead become a source of carbon to the atmosphere. Elevated carbon dioxide and climate change can affect vegetation growth through changing the assimilation of carbon dioxide and the respiration of carbon from the vegetation and soil. Using a dynamic global vegetation model, the Integrated BIosphere Simulator Model (IBIS), potential changes in both the biophysical and biogeochemical processes of Arctic vegetation were analyzed to determine how future climate change and elevated atmospheric carbon dioxide may alter their functioning and ability to store carbon. High latitude regions were modeled using a variety of temperature, precipitation, and carbon dioxide scenarios. Changes in gross and net primary production, net ecosystem exchange, soil carbon, soil respiration, leaf area index, and biomass content were analyzed. Under high levels of carbon dioxide, net primary production increased at a greater rate than high levels of warming. Soil carbon decreased dramatically with high levels of warming as soil respiration increased, but soil carbon increased with higher levels of atmospheric carbon dioxide as the vegetation fixed more carbon. Net primary production also increased in scenarios with elevated precipitation. The results from the combined scenarios of climate and atmospheric carbon

  16. The Northern Bering Sea: An Arctic Ecosystem in Change

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    Arctic systems can be rich and diverse habitats for marine life in spite of the extreme cold environment. Benthic faunal populations and associated biogeochemical cycling processes are influenced by sea-ice extent, seawater hydrography (nutrients, salinity, temperature, currents), and water column production. Benthic organisms on the Arctic shelves and margins are long-term integrators of overlying water column processes. Because these organisms have adapted to living at cold extremes, it is reasonable to expect that these communities will be among the most susceptible to climate warming. Recent observations show that Arctic sea ice in the North American Arctic is melting and retreating northward earlier in the season and the timing of these events can have dramatic impacts on the biological system. Changes in overlying primary production, pelagic-benthic coupling, and benthic production and community structure can have cascading effects to higher trophic levels, particularly benthic feeders such as walruses, gray whales, and diving seaducks. Recent indicators of contemporary Arctic change in the northern Bering Sea include seawater warming and reduction in ice extent that coincide with our time-series studies of benthic clam population declines in the shallow northern Bering shelf in the 1990's. In addition, declines in benthic amphipod populations have also likely influenced the movement of feeding gray whales to areas north of Bering Strait during this same time period. Finally a potential consequence of seawater warming and reduced ice extent in the northern Bering Sea could be the northward movement of bottom feeding fish currently in the southern Bering Sea that prey on benthic fauna. This would increase the feeding pressure on the benthic prey base and enhance competition for this food source for benthic-feeding marine mammals and seabirds. This presentation will outline recent biological changes observed in the northern Bering Sea ecosystem as documented in

  17. Sea-ice melt CO2-carbonate chemistry in the western Arctic Ocean: meltwater contributions to air-sea CO2 gas exchange, mixed layer properties and rates of net community production under sea ice

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Garley, R.; Frey, K. E.; Shake, K. L.; Mathis, J. T.

    2014-01-01

    The carbon dioxide (CO2)-carbonate chemistry of sea-ice melt and co-located, contemporaneous seawater has rarely been studied in sea ice covered oceans. Here, we describe the CO2-carbonate chemistry of sea-ice melt (both above sea ice as "melt ponds" and below sea ice as "interface waters") and mixed layer properties in the western Arctic Ocean in the early summer of 2010 and 2011. At nineteen stations, the salinity (~ 0.5 to < 6.5), dissolved inorganic carbon (DIC; ~ 20 to < 550 μmol kg-1) and total alkalinity (TA; ~ 30 to < 500 μmol kg-1) of above-ice melt pond water was low compared to water in the underlying mixed layer. The partial pressure of CO2 (pCO2) in these melt ponds was highly variable (~ < 10 to > 1500 μatm) with the majority of melt ponds acting as potentially strong sources of CO2 to the atmosphere. The pH of melt pond waters was also highly variable ranging from mildly acidic (6.1 to 7) to slightly more alkaline than underlying seawater (8 to 10.7). All of observed melt ponds had very low (< 0.1) saturation states (Ω) for calcium carbonate (CaCO3) minerals such as aragonite (Ωaragonite). Our data suggests that sea ice generated "alkaline" or "acidic" melt pond water. This melt-water chemistry dictates whether the ponds are sources of CO2 to the atmosphere or CO2 sinks. Below-ice interface water CO2-carbonate chemistry data also indicated substantial generation of alkalinity, presumably owing to dissolution of calcium CaCO3 in sea ice. The interface waters generally had lower pCO2 and higher pH/Ωaragonite than the co-located mixed layer beneath. Sea-ice melt thus contributed to the suppression of mixed layer pCO2 enhancing the surface ocean's capacity to uptake CO2 from the atmosphere. Meltwater contributions to changes in mixed-layer DIC were also used to estimate net community production rates (mean of 46.9 ±29.8 g C m-2 for the early-season period) under sea-ice cover. Although sea-ice melt is a transient seasonal feature, above-ice melt

  18. Cretaceous Arctic magmatism: Slab vs. plume? Or slab and plume?

    NASA Astrophysics Data System (ADS)

    Gottlieb, E. S.; Miller, E. L.; Andronikov, A. V.; Brumley, K.; Mayer, L. A.; Mukasa, S. B.

    2010-12-01

    Tectonic models for the Cretaceous paleogeographic evolution of the Arctic Ocean and its adjacent landmasses propose that rifting in the Amerasia Basin (AB) began in Jura-Cretaceous time, accompanied by the development of the High Arctic Large Igneous Province (HALIP). During the same timespan, deformation and slab-related magmatism, followed by intra-arc rifting, took place along the Pacific side of what was to become the Arctic Ocean. A compilation and comparison of the ages, characteristics and space-time variation of circum-Arctic magmatism allows for a better understanding of the role of Pacific margin versus Arctic-Atlantic plate tectonics and the role of plume-related magmatism in the origin of the Arctic Ocean. In Jura-Cretaceous time, an arc built upon older terranes overthrust the Arctic continental margins of North America and Eurasia, shedding debris into foreland basins in the Brooks Range, Alaska, across Chukotka, Russia, to the Lena Delta and New Siberian Islands region of the Russian Arctic. These syn-tectonic sediments have some common sources (e.g., ~250-300 Ma magmatic rocks) as determined by U-Pb detrital zircon geochronology. They are as young as Valanginian-Berriasian (~136 Ma, Gradstein et al., 2004) and place a lower limit on the age of formation of the AB. Subsequent intrusions of granitoid plutons, inferred to be ultimately slab-retreat related, form a belt along the far eastern Russian Arctic continental margin onto Seward Peninsula and have yielded a continuous succession of zircon U-Pb ages from ~137-95 Ma (n=28) and a younger suite ~91-82 Ma (n=16). All plutons dated were intruded in an extensional tectonic setting based on their relations to wall-rock deformation. Regional distribution of ages shows a southward migration of the locus of magmatism during Cretaceous time. Basaltic lavas as old as 130 Ma and as young as 80 Ma (40Ar/39Ar)) erupted across the Canadian Arctic Islands, Svalbard and Franz Josef Land and are associated with

  19. Arctic Energy Resources: Energy Research

    NASA Astrophysics Data System (ADS)

    Gryc, George

    1984-04-01

    Arctic Energy Resources is a volume of 26 papers recording the proceedings of the Comite' Arctique International Conference, held at the Veritas Centre, Oslo, Norway, September 22-24, 1982. This was the fourth of a series of meetings on the Arctic organized by the Comite', an organization established in the Principality of Monaco with the active support of H.S.H. Prince Rainer III. The fourth Conference was opened by H.R.H. Crown Prins Harald of Norway, a noble beginning for a noble objective.The North Polar Region has drawn world attention recently because of several large hydrocarbon and other mineral discoveries and because of major political and environmental actions in the North American Arctic. Since 1923 when Naval Petroleum Reserve number 4 (NPR-4) was established, northern Alaska has been considered a major petroleum province. It was first explored systematically with modern techniques from 1943 to 1953. In 1958, Alaska became a state, and both federal and state lands in northern Alaska were available for private exploration. Building on the knowledge base provided by the Pet-4 program and its spinoff research laboratory at Barrow, industry explored the area east of NPR-4 and discovered the largest hydrocarbon accumulation (9.6 bbl crude oil and 26 Tcf (trillion cubic feet) gas) in North America at Prudhoe Bay. Concerns for environmental impacts, including oil spills, led to the passing of the National Environmental Policy Act in 1969. In 1970, over 9 million acres were set aside, now known as the Arctic National Wildlife Range, and in 1971 the Alaska Native Claims Settlement Act was passed by the U.S. Congress. The Arab oil embargo of 1973 heightened the energy crisis and changed the economic basis for further exploration in the Arctic. The convergence of these events dramatically changed the balance of power and the pace of activity in the North American Arctic.

  20. Method for determination of organohalogen pesticide residues in vegetable oil refinery by-products.

    PubMed

    Young, S; Clower, M; Roach, J A

    1984-01-01

    A method using gel permeation and Florisil column chromatographic cleanup techniques is described for determination of residues of nonpolar organohalogen pesticides and pesticide alteration products in vegetable oils and their refinery by-products. Supplemental Florisil separation and alkali cleanup techniques are used to facilitate determinations. Residues are determined with a 63Ni electron capture gas chromatographic detection system used in conjunction with 3 different gas chromatographic columns. Residue identities are confirmed by gas chromatography-mass spectrometry. Recoveries of 7 organohalogen pesticides, ranging from 90 to 103%, were determined by the supplemental Florisil separation technique to augment previously reported recovery data determined for initial GPC and Florisil cleanup steps. Soybean, peanut, and cottonseed deodorizer distillates and crude and refined oil, as well as additional refinery by-products, were analyzed. Nine to 13 organohalogen residues ranging from 0.5 to 6.3 ppm were determined in the 2 soybean deodorizer distillate samples used to develop and test the method. Identities of residues present at greater than or equal to 0.3 ppm were confirmed by gas chromatography-mass spectrometry. An intralaboratory trial of the method provided additional recovery and residue determination data as follows: Recoveries ranging from 102 to 116% were obtained for 4 pesticides added to peanut oil deodorizer distillate. Residues determined in 1 soybean deodorizer distillate sample supported previously obtained data for this sample. PMID:6698936

  1. Evidence of 60 meter deep Arctic pressure-ridge keels

    SciTech Connect

    Reimnitz, E.; Barnes, P.W.; Phillips, R.L.

    1985-11-01

    Numerous efforts have been made during the last two decades to determine the ice thickness distribution in the Arctic Ocean and in particular to learn the keel depth of the largest modern pressure ridges. With the discovery of oil and gas in the arctic offshore and the trend to extend exploration into deeper water and increasing distance from shore, knowledge of the maximum ice thickness in the continental shelf is becoming increasingly important. Various approaches have been used to directly obtain keel depth data in the Arctic, but no satisfactory technique for water depths of less than 100 meters exists. For continental shelves, virtually all public data on ridge keel configuration stems from spot measurements made with horizontally held sonar transducers lowered through the ice adjacent to ridges, and from cores of ridges. Because these techniques are time-consuming, the depths of only a few ridge keels have been determined by such methods. Fixed upward-looking sonar devices have been used with limited success in several applications to record under-ice relief and movement, but any data so obtained is not public. This report is an attempt to interpret the age of deepwater gouges seen on the Alaskan Arctic shelf.

  2. Examining the Mid- Brunhes Event in the Terrestrial Arctic: an Organic Geochemical Record from Lake El'gygytgyn, Russia

    NASA Astrophysics Data System (ADS)

    Habicht, H.; Castañeda, I. S.; Brigham-Grette, J.

    2015-12-01

    The characteristic glacial and interglacial cycles of the Pleistocene underwent a climatic transition at ~430 ka known as the Mid- Brunhes Event (MBE). Numerous studies have noted that after this transition, the amplitude of the climatic cycles increased. Despite the indication of an MBE signal in many globally distributed paleoclimate records, the geographic extent of the climatic transition remains unknown. While the MBE is expressed in a number of southern hemisphere records its presence in northern hemisphere and terrestrial records is debated. Lake El'gygytgyn is located in the far- east Russian Arctic and provides the longest, most continuous record of Arctic climate (3.6 Ma). This study examines organic biomarkers in the Lake El'gygytgyn sediment core to determine if the MBE is expressed in the terrestrial Arctic. The paleoclimate reconstruction spans the interval of 0- 730 ka at a resolution of ~1.5 ka. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are utilized to reconstruct temperature variability and plant leaf wax n-alkanes are used to examine vegetation changes throughout the study interval. Statistical analysis of this, and other existing proxy data, indicates that a signal of the MBE is preserved in the Lake El'gygytgyn sediment record. BrGDGT temperature reconstructions indicate the terrestrial Arctic experienced both the warmest interglacial periods and coldest glacial periods after the MBE climatic transition. Arid glacial intervals and wetter interglacials are recorded by changes in the average chain length of n- alkanes, with wetter interglacials predominating after the MBE. Possibly, changes in Antarctic bottom water production and associated variability in North Pacific upwelling are responsible for transmitting the MBE signal from the southern hemisphere to Lake El'gygytgyn.

  3. Arctic Ocean circulation during the anoxic Eocene Azolla event

    NASA Astrophysics Data System (ADS)

    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

  4. Summer (sub-arctic) versus winter (sub-tropical) production affects on spinach leaf bio-nutrients: Vitamins (C, E, Folate, K1, provitamin A), lutein, phenolics, and antioxidants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparison of spinach (Spinacia oleracea L.) cultivars Lazio and Samish grown during the summer solstice in the sub-arctic versus the winter solstice in the sub-tropics provided insight into interactions between plant environment (day length, light intensity, ambient temperatures), cultivar and leaf...

  5. STANDARD PRACTICE FOR FULL-SCALE CHAMBER DETERMINATION OF VOLATILE ORAGNIC EMISSIONS FROM INDOOR MATERIALS/PRODUCTS

    EPA Science Inventory

    The Practice is intended for determining volatile organic compound (VOC) emissions from materials and products (building materials, material systems, furniture, consumer products, etc.) and equipment (printers, photocopiers, air cleaners, etc.) under environmental and product-usa...

  6. 21 CFR 601.25 - Review procedures to determine that licensed biological products are safe, effective, and not...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested... determine that licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested conditions of use. For purposes of reviewing biological products that have...

  7. 21 CFR 601.25 - Review procedures to determine that licensed biological products are safe, effective, and not...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested... determine that licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested conditions of use. For purposes of reviewing biological products that have...

  8. 21 CFR 601.25 - Review procedures to determine that licensed biological products are safe, effective, and not...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested... determine that licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested conditions of use. For purposes of reviewing biological products that have...

  9. 21 CFR 601.25 - Review procedures to determine that licensed biological products are safe, effective, and not...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested... determine that licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested conditions of use. For purposes of reviewing biological products that have...

  10. 21 CFR 601.25 - Review procedures to determine that licensed biological products are safe, effective, and not...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested... determine that licensed biological products are safe, effective, and not misbranded under prescribed, recommended, or suggested conditions of use. For purposes of reviewing biological products that have...

  11. Arctic Research NASA's Cryospheric Sciences Program

    NASA Technical Reports Server (NTRS)

    Waleed, Abdalati; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Much of NASA's Arctic Research is run through its Cryospheric Sciences Program. Arctic research efforts to date have focused primarily on investigations of the mass balance of the largest Arctic land-ice masses and the mechanisms that control it, interactions among sea ice, polar oceans, and the polar atmosphere, atmospheric processes in the polar regions, energy exchanges in the Arctic. All of these efforts have been focused on characterizing, understanding, and predicting, changes in the Arctic. NASA's unique vantage from space provides an important perspective for the study of these large scale processes, while detailed process information is obtained through targeted in situ field and airborne campaigns and models. An overview of NASA investigations in the Arctic will be presented demonstrating how the synthesis of space-based technology, and these complementary components have advanced our understanding of physical processes in the Arctic.

  12. U.S. Arctic Research Commission

    NASA Astrophysics Data System (ADS)

    “North to the Future” is a well-known slogan in Alaska. This slogan also expresses the spirit with which the U.S. Arctic Research Commission (ARC) has begun its work.The commission was established as a result of Sen. Murkowski's (R-Alaska) Arctic Research and Policy Act of 1984, and its members were appointed by President Reagan last February (Eos, February 26, 1985, p. 91). The ARC has been directed to develop and recommend an integrated Arctic research policy and to work with the concomitantly established Interagency Arctic Research Policy Committee in the formulation of a comprehensive 5-year Arctic research plan (see Figure 1). The Arctic Research and Policy Act designates the National Science Foundation as the lead agency responsible for implementing the policy with other federal agencies; it further requires the preparation of a single, integrated multiagency budget request for Arctic research.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Changing Arctic ecosystems: ecology of loons in a changing Arctic

    USGS Publications Warehouse

    Uher-Koch, Brian; Schmutz, Joel; Whalen, Mary; Pearce, John M.

    2014-01-01

    The U.S. Geological Survey (USGS) Changing Arctic Ecosystems (CAE) initiative informs key resource management decisions for Arctic Alaska by providing scientific information on current and future ecosystem response to a changing climate. From 2010 to 2014, a key study area for the USGS CAE initiative has been the Arctic Coastal Plain of northern Alaska. This region has experienced rapid warming during the past 30 years, leading to the thawing of permafrost and changes to lake and river systems. These changes, and projections of continued change, have raised questions about effects on wildlife populations that rely on northern lake ecosystems, such as loons. Loons rely on freshwater lakes for nesting habitat and the fish and invertebrates inhabiting the lakes for food. Loons live within the National Petroleum Reserve-Alaska (NPR-A) on Alaska’s northern coast, where oil and gas development is expected to increase. Research by the USGS examines how breeding loons use the Arctic lake ecosystem and the capacity of loons to adapt to future landscape change.

  15. 16 CFR 1500.89 - Procedures and requirements for determinations regarding lead content of materials or products...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... review of the staff's final recommendation, determines that a material or product does not and would not... determinations regarding lead content of materials or products under section 101(a) of the Consumer Product Safety Improvement Act. 1500.89 Section 1500.89 Commercial Practices CONSUMER PRODUCT SAFETY...

  16. 16 CFR 1500.89 - Procedures and requirements for determinations regarding lead content of materials or products...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... review of the staff's final recommendation, determines that a material or product does not and would not... determinations regarding lead content of materials or products under section 101(a) of the Consumer Product Safety Improvement Act. 1500.89 Section 1500.89 Commercial Practices CONSUMER PRODUCT SAFETY...

  17. 16 CFR 1500.89 - Procedures and requirements for determinations regarding lead content of materials or products...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... review of the staff's final recommendation, determines that a material or product does not and would not... determinations regarding lead content of materials or products under section 101(a) of the Consumer Product Safety Improvement Act. 1500.89 Section 1500.89 Commercial Practices CONSUMER PRODUCT SAFETY...

  18. Post-glacial variability of sea ice cover, river run-off and biological production in the western Laptev Sea (Arctic Ocean) - A high-resolution biomarker study

    NASA Astrophysics Data System (ADS)

    Hörner, T.; Stein, R.; Fahl, K.; Birgel, D.

    2016-07-01

    Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), biological production (brassicasterol, dinosterol) and river run-off (campesterol, β-sitosterol) in the western Laptev Sea over the last ∼17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted biological production occurred during this cold interval. From ∼16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bølling/Allerød warm period (14.7-12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice-coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9-11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 ± 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level

  19. Determination of seven certified color additives in food products using liquid chromatography.

    PubMed

    Harp, Bhakti Petigara; Miranda-Bermudez, Enio; Barrows, Julie N

    2013-04-17

    This study describes a new method for determining FD&C Blue No. 1, FD&C Blue No. 2, FD&C Green No. 3, FD&C Red No. 3, FD&C Red No. 40, FD&C Yellow No. 5, and FD&C Yellow No. 6 in food products. These seven color additives are water-soluble dyes that are required to be batch certified by the U.S. Food and Drug Administration (FDA) before they may be used in food and other FDA-regulated products. In the new method, the color additives are extracted from a product using one of two procedures developed for various product types, isolated from the noncolored components, and analyzed by liquid chromatography with photodiode array detection. The method was validated by determining linearity, range, precision, recovery from various matrices, limit of detection, limit of quantitation, and relative standard deviation for each color additive. A survey of 44 food products, including beverages, frozen treats, powder mixes, gelatin products, candies, icings, jellies, spices, dressings, sauces, baked goods, and dairy products, found total color additives ranging from 1.9 to 1221 mg/kg. FDA intends to use the new method for conducting a rigorous, comprehensive dietary exposure assessment of certified color additives in products likely to be consumed by children. PMID:23528012

  20. Coupled ecosystem carbon and nutrient cycling in a High Arctic ecosystem are altered by long-term experimental warming and higher rainfall

    NASA Astrophysics Data System (ADS)

    Schaeffer, S. M.; Schimel, J.; Welker, J. M.

    2013-12-01

    The rapid changes in temperature and precipitation in High Arctic tundra ecosystems are altering the biogeochemical cycles of nitrogen (N) and carbon (C), but in ways that are difficult to anticipate. The challenge grows from the complexity of tundra soil organic matter, the uncertainty of N cycle responses and the extent to which shifts in soil N processes are coupled with the C cycle, including leaf-level photosynthesis, gross ecosystem photosynthesis (GEP-productivity) and net CO2 exchange (NEE-C sequestration). Understanding the processes that are leading to changes in High Arctic biogeochemical processes are especially important today as soil organic C pools in the High Arctic are up to 6 times greater than previously estimated, and are sensitive to being oxidized to the atmosphere through changes in microbial decomposition associated with warmer and wetter conditions. We used a long-term (since 2003) experiment of summer warming and supplemental summer water additions to a High Arctic ecosystem in NW Greenland to determine the impact of interactions between temperature, water availability, and microbial metabolism on the cycling of C and plant-available N in High Arctic tundra soil. We have found that water availability plays a critical role in these cycles in High Arctic tundra, over and above that from temperature increases. On seasonal time scales, we observed greater net N mineralization under both global change scenarios, yet water addition also significantly increased net nitrification rates, loss of NO3--N via leaching from surface soil layers, and lowered rates of labile organic C and N production. We also expected the chronic warming and watering would lead to long-term changes in soil N-cycling that would be reflected in soil δ15N values. However, we found that soil δ15N decreased under the different climate change scenarios. Our findings indicate that warmer, wetter High Arctic tundra will be cycling N and C in ways that may transform these

  1. Determination of {sup 140}La fission product interference factor for INAA

    SciTech Connect

    Ribeiro Jr, Iberê S.; Genezini, Frederico A.; Saiki, Mitiko; Zahn, Guilherme S.

    2014-11-11

    Instrumental Neutron Activation Analysis (INAA) is a technique widely used to determine the concentration of several elements in several kinds of matrices. However if the sample of interest has higher relative uranium concentration the obtained results can be interfered by the uranium fission products. One of these cases that is affected by interference due to U fission is the {sup 140}La, because this radioisotope used in INAA for the determination of concentration the La is also produced by the {sup −}β of {sup 140}Ba, an uranium fission product. The {sup 140}La interference factor was studied in this work and a factor to describe its time dependence was obtained.

  2. Formation of distinct soluble microbial products by activated sludge: kinetic analysis and quantitative determination.

    PubMed

    Ni, Bing-Jie; Fang, Fang; Xie, Wen-Ming; Xu, Juan; Yu, Han-Qing

    2012-02-01

    Soluble microbial products (SMP) released by microorganisms in bioreactors are classified into two distinct groups according to their different chemical and degradation kinetics: utilization-associated products (UAP) and biomass-associated products (BAP). SMP are responsible for effluent chemical oxygen demand or for membrane fouling of membrane bioreactor. Here an effective and convenient approach, other than the complicated chemical methods or complex models, is developed to quantify the formation of UAP and BAP together with their kinetics in activated sludge process. In this approach, an integrated substrate utilization equation is developed and used to determine UAP and their production kinetics. On the basis of total SMP measurements, BAP formation is determined with an integrated BAP formation equation. The fraction of substrate electrons diverted to UAP, and the content of BAP derived from biomass can then be calculated. Dynamic quantification data are obtained for UAP and BAP separately and conveniently. The obtained kinetic parameters are found to be reasonable as they are generally bounded and comparable to the literature values. The validity of this approach is confirmed by independent SMP production tests in six different activated sludge systems, which demonstrates its applicability in a wide range of engineered system regarding SMP production. This work provides a widely applied approach to determine the formation of UAP and BAP conveniently, which may offer engineers with basis to optimize bioreactor operation to avoid a high effluent soluble organics from SMP or SMP-based membrane fouling in membrane bioreactors. PMID:22185635

  3. What controls past and present organic carbon fluxes in the Arctic Ocean? - New insights from biomarker records

    NASA Astrophysics Data System (ADS)

    Stein, R. H.; Fahl, K.; Xiao, X.; Meheust, M.; Müller, J.

    2012-12-01

    The past and present Arctic Ocean is characterized by distinct changes in sea-ice cover, sea-surface-temperature, river discharge, and oceanic circulation patterns. All these factors also influence the organic carbon (OC) input, preservation and burial in the continental margin and adjacent deep sea areas (cf., Stein and Macdonald, 2004; Stein, 2008). Thus, records of amount and composition of OC in marine surface sediments and sediment cores yield important information on the spatial and temporal variability of Arctic Ocean (paleo-)environments. Especially, biomarker data allow to distinguish between these different processes controlling/influencing OC accumulation in the Arctic Ocean. In this context, we determined concentrations of the sea-ice diatom-derived biomarker IP25 (highly-branched isoprenoid - HBI - with 25 carbon atom; Belt et al., 2007), phytoplankton-derived biomarkers (brassicasterol and dinosterol) and terrigenous biomarkers (e.g., campesterol and long-chain n-alkanes) to estimate recent sea-ice conditions and related surface-water processes in the study area. A combined phytoplankton-IP25 biomarker approach (PIP25 index) is used to reconstruct the modern sea-ice distribution more quantitatively (Müller et al., 2009, 2011; Fahl and Stein, 2012; Stein et al., 2012). Starting from distribution maps of the different biomarker proxies for terrigenous input, sea-ice and primary production and indicative for modern processes controlling OC accumulation, we continue with biomarker data obtained from selected Arctic Ocean sediment cores. The biomarker records from the sediment cores give insights into the variability in river discharge, primary productivity and sea ice as well as OC fluxes from the Last Glacial Maximum to recent times. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Org. Geochem. 38, 16-27. Fahl, K. and Stein, R., 2012. Modern seasonal

  4. Mercury in Arctic Marine Ecosystems: Sources, Pathways, and Exposure

    PubMed Central

    Kirk, Jane L.; Lehnherr, Igor; Andersson, Maria; Braune, Birgit M.; Chan, Laurie; Dastoor, Ashu P.; Durnford, Dorothy; Gleason, Amber L.; Loseto, Lisa L.; Steffen, Alexandra; St. Louis, Vincent L.

    2014-01-01

    Mercury in the Arctic is an important environmental and human health issue. The reliance of Northern Peoples on traditional foods, such as marine mammals, for subsistence means that they are particularly at risk from mercury exposure. The cycling of mercury in Arctic marine systems is reviewed here, with emphasis placed on the key sources, pathways and processes which regulate mercury levels in marine food webs and ultimately the exposure of human populations to this contaminant. While many knowledge gaps exist limiting our ability to make strong conclusions, it appears that the long range transport of mercury from Asian emissions is an important source of atmospheric Hg to the Arctic and that mercury methylation resulting in monomethylmercury production (an organic form of mercury which is both toxic and bioaccumulated) in Arctic marine waters is the principal source of mercury incorporated into food webs. Mercury concentrations in biological organisms have increased since the onset of the industrial age and are controlled by a combination of abiotic factors (e.g., monomethylmercury supply), food web dynamics and structure, and animal behavior (e.g., habitat selection and feeding behavior). Finally, although some Northern Peoples have high mercury concentrations of mercury in their blood and hair, harvesting and consuming traditional foods has many nutritional, social, cultural and physical health benefits which must be considered in risk management and communication. PMID:23102902

  5. Detecting the Signature of Permafrost Thaw in Arctic Rivers

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Mann, P. J.; Dittmar, T.; Eglinton, T. I.; Stubbins, A.

    2014-12-01

    Arctic permafrost soils contain vast quantities of ancient organic matter. Numerous studies have shown extensive permafrost thaw and degradation in the Arctic, but dissolved organic carbon (DOC) exported from the mouths of large Arctic rivers - which are expected to integrate processes and changes occurring through their watersheds - has been shown to be predominantly modern. This raises the question, where is the ancient DOC that is mobilized from permafrost thaw and the deepening of the active layer? This study examines DOC radiocarbon age, biolability and dissolved organic matter (DOM) composition via FT-ICR-MS in permafrost thaw streams and the Kolyma River mainstem (Northeast Siberia). Ancient permafrost thaw stream DOC is observed to be highly biolabile particularly in comparison to modern Kolyma River mainstem DOC. In conjunction with this high biolability the permafrost thaw stream DOM exhibits large changes in molecular structure, loss of hydrogen rich (energy rich) aliphatic molecules, and production of molecules in the classical area in van Krevelen space associated with riverine DOM. Modern Kolyma River mainstem DOM conversely appears very stable in bioincubations in comparison to ancient permafrost thaw DOM. Thus the apparent offset between mobilization of ancient permafrost derived organic matter and the current predominantly modern age of DOC at the mouth of major Arctic rivers may be explained due to microbial degradation of permafrost derived DOC within the river's hydrologic residence time.

  6. Weaving Arctic Networks of Support and Engaged Accountability

    NASA Astrophysics Data System (ADS)

    Warnick, W. K.

    2003-12-01

    This presentation will provide a preview of a new project which explores the potential of applying emerging educational research in conjunction with the latest polar research through a multifaceted approach designed to weave networks of support and engaged accountability between Arctic researchers, teachers, and learners. This presentation will outline how Sunwood's (2002) WoSEA educational model might be utilized to facilitate and study methods of engaging and supporting teachers and scientists in collaborative Arctic research and pedagogy. The model we are proposing employs action research methodology to provide educators and scientists the opportunity to engage in reflection on their own practice, and enhancement of their own practice through extensive connection and collaboration between education and scientific professionals, thus contributing to the cumulative development of a lifelong learning continuum. Our Weaving the Arctic project will amplify and enhance the voice, knowledge and expertise of Arctic researchers and teachers as each participant explores, shares, and showcases their experience, knowledge, and the products of their practice. Weaving thus holds great promise for addressing science education needs, particularly the critical needs surrounding enhancement and retention of STEM teachers in K-12 (especially rural) schools. This presentation will share the promise of our Weaving model.

  7. Arctic shorebirds in North America: a decade of monitoring

    USGS Publications Warehouse

    Bart, Jonathan R., (Edited By); Johnston, Victoria H.

    2012-01-01

    Each year shorebirds from North and South America migrate thousands of miles to spend the summer in the Arctic. There they feed in shoreline marshes and estuaries along some of the most productive and pristine coasts anywhere. With so much available food they are able to reproduce almost explosively; and as winter approaches, they retreat south along with their offspring, to return to the Arctic the following spring. This remarkable pattern of movement and activity has been the object of intensive study by an international team of ornithologists who have spent a decade counting, surveying, and observing these shorebirds. In this important synthetic work, they address multiple questions about these migratory bird populations. How many birds occupy Arctic ecosystems each summer? How long do visiting shorebirds linger before heading south? How fecund are these birds? Where exactly do they migrate and where exactly do they return? Are their populations growing or shrinking? The results of this study are crucial for better understanding how environmental policies will influence Arctic habitats as well as the far-ranging winter habitats used by migratory shorebirds.

  8. Systematic High-Resolution (30 meter) Inventory of Global Lakes: Pan-Arctic and Beyond

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Wang, J.; Smith, L. C.; Lyons, E. A.; Te, G.; Woods, J.; Garibay, D.; Knox, B.

    2014-12-01

    [Abstract] Lakes play a crucial role in the global water cycle and balance, are sensitive to global warming, and are vital for human water supply. There clearly is a pressing need to understand temporal and spatial variations in lake water storage globally, especially in the lake-rich Arctic/Sub-Arctic regions. An accurate systematic lake inventory, however, is unavailable at global scales. Owing to its broad spatial coverage and repeat-pass monitoring capability, satellite remote sensing is the only feasible approach to inventory global lake dynamics. Global lake mapping at high resolutions is a rather challenging task. Since lakes are abundant in small-size classes and their seasonality varies from region to region, a huge number of high-resolution satellite images need to be acquired in "appropriate" seasons. The appropriate seasons refer to the period in a typical year when lakes are relatively stable, and are determined spatially using precipitation and temperature datasets. Thousands of cloud-free Landsat images at 30 m resolution have been acquired during lake-stable seasons. Satellite lake mapping succeeds at different levels from place to place and from season to season. A set of highly replicable automated lake mapping methods and tools have been developed to tackle various situations across the entire Earth and to handle such a large volume of satellite data. The current goal is to produce a circa 2000 high-resolution global lake database in a systematic way. Millions of lakes larger than 0.5 ha have been inventoried. The product is currently examined in an intensive quality control and quality assurance process. Over six million lakes in pan-Arctic (45 deg N and above) are captured in the database and have been validated for release.

  9. Distribution of dissolved and particulate trace metals in Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Hendy, I. L.; Aciego, S.; Meyer, K.

    2014-12-01

    Iron (Fe) is an essential biolimiting micronutrient, however, the bioavailablility of Fe is dependent on source and speciation. In a high nutrient/low chlorophyll region of the ocean such as the Arctic, sea ice is an important aggregator of dissolved and particulate Fe from aerosol, lithogenic, and biogenic sources. While particulate Fe is less bioavailable than dissolved Fe, it is far more abundant in sea ice. As a result, sea ice directly enhances productivity by ice entrapment of mineral dust particulates containing Fe, which can be released into the surface ocean waters during melting. In seawater underlying sea ice, Fe can be concentrated up to two orders of magnitude higher than in the ice-free open ocean (Lannuzel et al., 2011). A transect of sea ice cores were collected in the spring of 2014 offshore of Barrow, AK, and the Canadian Arctic Archipelago to capture a gradient of sediment contributions from shelf sediments to aeolian sediments. At Barrow, AK, land fast first year ice was sampled. In the Canadian Arctic, both multi-year (pack ice) and first year (land fast) ice cores were retrieved. First year ice cores were between 100-150 cm thick and the multi year core was 195 cm thick. Cores were subsampled by depth and filtered. The resulting ice core sediments were analyzed for elemental composition, and multistep Fe-leaching experiments were conducted to determine the fraction of soluble Fe. Thus we have ascertained the solubility of particulate Fe prior to onset of melt season. Dissolved trace metals were also analyzed to ascertain changes in concentration with ice core depth of lithogenic elements (Mn, Al) and biologically important elements (Si, Mo, Cu, Zn). Preliminary results show some enrichment of lithogenic inputs near surface, indicating dust deposition, and lower portions of the cores, suggesting resuspended sediments from the continental shelf. Concentrations of some biologically important elements decrease with depth, suggesting possible

  10. Diverging Plant and Ecosystem Strategies in Response to Climate Change in the High Arctic

    NASA Astrophysics Data System (ADS)

    Maseyk, K. S.; Welker, J. M.; Czimczik, C. I.; Lupascu, M.; Lett, C.; Seibt, U. H.

    2014-12-01

    Increasing summer precipitation means Arctic growing seasons are becoming wetter as well as warmer, but the effect of these coupled changes on tundra ecosystem functioning remains largely unknown. We have determined how warmer and wetter summers affect coupled carbon-water cycling in a High Arctic polar semi-desert ecosystem in NW Greenland. Measurements of ecosystem CO2 and water fluxes throughout the growing season and leaf ecophysiological traits (gas exchange, morphology, leaf chemistry) were made at a long-term climate change experiment. After 9 years of exposure to warmer (+ 4°C) and / or wetter (+ 50% precipitation) treatments, we found diverging plant strategies between the responses to warming with or without an increase in summer precipitation. Warming alone resulted in an increase in leaf nitrogen, mesophyll conductance and leaf-mass per area and higher rates of leaf-level photosynthesis, but with warming and wetting combined leaf traits remain largely unchanged. However, total leaf area increased with warming plus wetting but was unchanged with warming alone. The combined effect of these leaf trait and canopy adjustments is a decrease in ecosystem water-use efficiency (the ratio of net productivity to evapotranspiration) with warming only, but a substantial increase with combined warming and wetting. We conclude that increasing summer precipitation will alter tundra ecohydrological responses to warming; that leaf-level changes in ecophysiological traits have an upward cascading consequence for ecosystem and land surface-climate interactions; and the current relative resistance of High Arctic ecosystems to warming may mask biochemical and carbon cycling changes already underway.

  11. [Development of Determination Method of Ipfencarbazone in Agricultural Products, Livestock Products and Seafood by LC-MS/MS].

    PubMed

    Imai, Koichi; Onoue, Keiko; Ishii, Rie; Takano, Mariko; Nemoto, Satoru; Teshima, Reiko

    2015-01-01

    A method for the determination of ipfencarbazone in agricultural products, livestock products and seafood by LC-MS/MS was developed. Agricultural samples were extracted with acetone. An aliquot of crude extract was partitioned with n-hexane and sat. sodium chloride solution. Clean-up was performed using GC/PSA and C18 cartridges. In the case of livestock products and seafood, samples were extracted with a mixture of acetone and n-hexane, and the organic layer was collected. After acetonitrile-hexane partitioning, the extract was cleaned up using PAS and C18 cartridges. The gradient LC separation was performed on a C18 column with acetonitrile-water containing acetic acid as a mobile phase, and MS with positive ion electrospray ionization was used for detection. The average recoveries (n=5) of ipfencarbazone from 16 kinds of agricultural products, livestock products and seafood spiked at the MRLs or at the uniform limits (0.01 ppm) were 73-101%, and the relative standard deviations were 1.3-5.1%. The limit of quantitation of the developed method was 0.01 mg/kg for ipfencarbazone. PMID:26537650

  12. Does Arctic sea ice reduction foster shelf-basin exchange?

    PubMed

    Ivanov, Vladimir; Watanabe, Eiji

    2013-12-01

    The recent shift in Arctic ice conditions from prevailing multi-year ice to first-year ice will presumably intensify fall-winter sea ice freezing and the associated salt flux to the underlying water column. Here, we conduct a dual modeling study whose results suggest that the predicted catastrophic consequences for the global thermohaline circulation (THC), as a result of the disappearance of Arctic sea ice, may not necessarily occur. In a warmer climate, the substantial fraction of dense water feeding the Greenland-Scotland overflow may form on Arctic shelves and cascade to the deep basin, thus replenishing dense water, which currently forms through open ocean convection in the sub-Arctic seas. We have used a simplified model for estimating how increased ice production influences shelf-basin exchange associated with dense water cascading. We have carried out case studies in two regions of the Arctic Ocean where cascading was observed in the past. The baseline range of buoyancy-forcing derived from the columnar ice formation was calculated as part of a 30-year experiment of the pan-Arctic coupled ice-ocean general circulation model (GCM). The GCM results indicate that mechanical sea ice divergence associated with lateral advection accounts for a significant part of the interannual variations in sea ice thermal production in the coastal polynya regions. This forcing was then rectified by taking into account sub-grid processes and used in a regional model with analytically prescribed bottom topography and vertical stratification in order to examine specific cascading conditions in the Pacific and Atlantic sectors of the Arctic Ocean. Our results demonstrate that the consequences of enhanced ice formation depend on geographical location and shelf-basin bathymetry. In the Pacific sector, strong density stratification in slope waters impedes noticeable deepening of shelf-origin water, even for the strongest forcing applied. In the Atlantic sector, a 1.5x increase of

  13. Intercomparison of satellite-derived cloud analyses for the Arctic Ocean in spring and summer

    NASA Technical Reports Server (NTRS)

    Mcguffie, K.; Barry, R. G.; Schweiger, A.; Newell, J.; Robinson, D. A.

    1988-01-01

    Several methods of deriving Arctic cloud information, primarily from satellite imagery, have been intercompared. The comparisons help in establishing what cloud information is most readily determined in polar regions from satellite data analysis. The analyses for spring-summer conditions show broad agreement, but subjective errors affecting some geographical areas and cloud types are apparent. The results suggest that visible and thermal infrared data may be insufficient for adequate cloud mapping over some Arctic surfaces.

  14. Clamp for arctic pipeline support

    SciTech Connect

    Morton, A.W.

    1988-11-29

    This patent describes a ring clamp for supporting and anchoring a large diameter metallic arctic pipeline comprising substantially rigid, curved clamp portions adapted to completely encircle the pipeline and fastening means connecting the clamp portions, the clamp portions having inner and outer layers of fiber reinforced rigid polymer material and an intermediate core layer of honeycomb-form aramid paper.

  15. Computational problems in Arctic Research

    NASA Astrophysics Data System (ADS)

    Petrov, I.

    2016-02-01

    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.

  16. Arctic Sea Ice, Summer 2014

    NASA Video Gallery

    An animation of daily Arctic sea ice extent in summer 2014, from March 21, 2014 to Sept. 17, 2014 – when the ice appeared to reach it’s minimum extent for the year. It’s the sixth lowest minimum se...

  17. Endoparasites in the feces of arctic foxes in a terrestrial ecosystem in Canada

    PubMed Central

    Elmore, Stacey A.; Lalonde, Laura F.; Samelius, Gustaf; Alisauskas, Ray T.; Gajadhar, Alvin A.; Jenkins, Emily J.

    2013-01-01

    The parasites of arctic foxes in the central Canadian Arctic have not been well described. Canada’s central Arctic is undergoing dramatic environmental change, which is predicted to cause shifts in parasite and wildlife species distributions, and trophic interactions, requiring that baselines be established to monitor future alterations. This study used conventional, immunological, and molecular fecal analysis techniques to survey the current gastrointestinal endoparasite fauna currently present in arctic foxes in central Nunavut, Canada. Ninety-five arctic fox fecal samples were collected from the terrestrial Karrak Lake ecosystem within the Queen Maud Gulf Migratory Bird Sanctuary. Samples were examined by fecal flotation to detect helminths and protozoa, immunofluorescent assay (IFA) to detect Cryptosporidium and Giardia, and quantitative PCR with melt-curve analysis (qPCR-MCA) to detect coccidia. Positive qPCR-MCA products were sequenced and analyzed phylogenetically. Arctic foxes from Karrak Lake were routinely shedding eggs from Toxascaris leonina (63%). Taeniid (15%), Capillarid (1%), and hookworm eggs (2%), Sarcocystis sp. sporocysts 3%), and Eimeria sp. (6%), and Cystoisospora sp. (5%) oocysts were present at a lower prevalence on fecal flotation. Cryptosporidium sp. (9%) and Giardia sp. (16%) were detected by IFA. PCR analysis detected Sarcocystis (15%), Cystoisospora (5%), Eimeria sp., and either Neospora sp. or Hammondia sp. (1%). Through molecular techniques and phylogenetic analysis, we identified two distinct lineages of Sarcocystis sp. present in arctic foxes, which probably derived from cervid and avian intermediate hosts. Additionally, we detected previously undescribed genotypes of Cystoisospora. Our survey of gastrointestinal endoparasites in arctic foxes from the central Canadian Arctic provides a unique record against which future comparisons can be made. PMID:24533320

  18. Relative fission product yield determination in the USGS TRIGA Mark I reactor

    NASA Astrophysics Data System (ADS)

    Koehl, Michael A.

    Fission product yield data sets are one of the most important and fundamental compilations of basic information in the nuclear industry. This data has a wide range of applications which include nuclear fuel burnup and nonproliferation safeguards. Relative fission yields constitute a major fraction of the reported yield data and reduce the number of required absolute measurements. Radiochemical separations of fission products reduce interferences, facilitate the measurement of low level radionuclides, and are instrumental in the analysis of low-yielding symmetrical fission products. It is especially useful in the measurement of the valley nuclides and those on the extreme wings of the mass yield curve, including lanthanides, where absolute yields have high errors. This overall project was conducted in three stages: characterization of the neutron flux in irradiation positions within the U.S. Geological Survey TRIGA Mark I Reactor (GSTR), determining the mass attenuation coefficients of precipitates used in radiochemical separations, and measuring the relative fission products in the GSTR. Using the Westcott convention, the Westcott flux, modified spectral index, neutron temperature, and gold-based cadmium ratios were determined for various sampling positions in the USGS TRIGA Mark I reactor. The differential neutron energy spectrum measurement was obtained using the computer iterative code SAND-II-SNL. The mass attenuation coefficients for molecular precipitates were determined through experiment and compared to results using the EGS5 Monte Carlo computer code. Difficulties associated with sufficient production of fission product isotopes in research reactors limits the ability to complete a direct, experimental assessment of mass attenuation coefficients for these isotopes. Experimental attenuation coefficients of radioisotopes produced through neutron activation agree well with the EGS5 calculated results. This suggests mass attenuation coefficients of molecular

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

    NASA Astrophysics Data System (ADS)

    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].

  20. MabCent: Arctic marine bioprospecting in Norway.

    PubMed

    Svenson, Johan

    2013-01-01

    The deep waters surrounding the coastline of the northern parts of Norway represent an exciting biotope for marine exploration. Dark and cold Arctic water generates a hostile environment where the ability to adapt is crucial to survival. These waters are nonetheless bountiful and a diverse plethora of marine organisms thrive in these extreme conditions, many with the help of specialised chemical compounds. In comparison to warmer, perhaps more inviting shallower tropical waters, the Arctic region has not been as thoroughly investigated. MabCent is a Norwegian initiative based in Tromsø that aims to change this. Since 2007, scientists within MabCent have focussed their efforts on the study of marine organisms inhabiting the Arctic waters with the long term goal of novel drug discovery and development. The activities of MabCent are diverse and range from sampling the Arctic ice shelf to the chemical synthesis of promising secondary metabolites discovered during the screening process. The current review will present the MabCent pipeline from isolation to identification of new bioactive marine compounds via an extensive screening process. An overview of the main activities will be given with particular focus on isolation strategies, bioactivity screening and structure determination. Pitfalls, hard earned lessons and the results so far are also discussed. PMID:24078803

  1. Determination of the decomposition products of Usal in model systems and determination of dioxopiperazine in soft drinks by HPLC.

    PubMed

    Prudel, M; Davídková, E

    1985-01-01

    A HPLC method for the determination of Usal (Aspartame hydrochloride, L-aspartyl-L-phenylalanine methyl ester hydrochloride) and its decomposition products was elaborated. Aspartic acid, phenylalanine, phenylalanine methyl ester, aspartyl-phenylalanine, phenylalanyl-aspartic acid, 5-benzyl-3,6-dioxo-2-piperazineacetic acid (DOP) and Usal were separated on Separon SI C-18. The mobile phase was: 0.5 M NaH2PO4 (pH 2.1) and methanol (85:15 v/v). The detection was carried out at 200 nm. The method for DOP determination was tested by the analysis of 10 types of soft drinks to which DOP was added. In two newly developed sorts of soft drinks sweetened with Usal the formation of DOP was followed during storage. The DOP increment after 34 days of storage reached 0.7 and 6 mg/l at 7 and 20 degrees C, resp. The method is also suitable for DOP determination in the sweetener itself. PMID:4022104

  2. Interact - Access to the Arctic

    NASA Astrophysics Data System (ADS)

    Johansson, M.; Callaghan, T. V.

    2013-12-01

    INTERACT is currently a network of 50 terrestrial research stations from all Arctic countries, but is still growing. The network was inaugurated in January 2011 when it received an EU 7th Framework award. INTERACT's main objective is to build capacity for identifying, understanding, predicting and responding to diverse environmental changes throughout the wide environmental and land-use envelopes of the Arctic. Implicit in this objective is the task to build capacity for monitoring, research, education and outreach. INTERACT is increasing access to the Arctic: 20 INTERACT research stations in Europe and Russia are offering Transnational Access and so far, 5600 person-days of access have been granted from the total of 10,000 offered. An INTERACT Station Managers' Forum facilitates a dialogue among station managers on subjects such as best practice in station management and standardised monitoring. The Station Managers' Forum has produced a unique 'one-stop-shop' for information from 45 research stations in an informative and attractive Station Catalogue that is available in hard copy and on the INTERACT web site (www.eu-interact.org). INTERACT also includes three joint research activities that are improving monitoring in remote, harsh environments and are making data capture and dissemination more efficient. Already, new equipment for measuring feedbacks from the land surface to the climate system has been installed at several locations, while best practices for sensor networking have been established. INTERACT networks with most of the high-level Arctic organisations: it includes AMAP and WWF as partners, is endorsed by IASC and CBMP, has signed MoUs with ISAC and the University of the Arctic, is a task within SAON, and contributes to the Cold Region community within GEO/GEOSS. INTERACT welcomes other interactions.

  3. Determination of absolute configuration of natural products: theoretical calculation of electronic circular dichroism as a tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of absolute configuration (AC) is one of the most challenging features in the structure elucidation of chiral natural products, especially those with complex structures. With revolutionary advancements in the area of quantum chemical calculations of chiroptical spectroscopy over the pa...

  4. Determinants of Adoption of Improved Fish Production Technologies among Fish Farmers in Delta State, Nigeria

    ERIC Educational Resources Information Center

    Ofuoku, A. U.; Olele, N. F.; Emah, G. N.

    2008-01-01

    This study was conducted to isolate the determinants of improved fish production technologies in Delta State, Nigeria. Data were collected from a sample population of 250 fish farmers from ten randomly selected Local Government Areas of Delta State. The data were elicited from respondents with the use of structured interview schedule while…

  5. Determination of Cooking Yields and Nutrient Retention Factors of Choline in Meat Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    USDA’s recent research shows that meat products are good sources of choline. During cooking, nutrient levels are affected by moisture and fat losses and may be reduced by heating. To determine the impact of cooking on choline retention in meats, four nationwide composite samples of beef, bacon, cure...

  6. 78 FR 17429 - Certain Balloon Dissection Devices and Products Containing Same; Commission Determination Not To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-21

    ..., Massachusetts (``Covidien'') on December 21, 2012. 78 FR 6838 (January 31, 2013). The complaint alleged... COMMISSION Certain Balloon Dissection Devices and Products Containing Same; Commission Determination Not To..., the importation, or sale in the United States after importation of certain balloon dissection...

  7. 76 FR 59141 - Determination That LOXITANE (Loxapine Succinate) Capsules and Three Other Drug Products Were Not...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Determination That LOXITANE (Loxapine Succinate) Capsules and Three Other Drug Products Were Not Withdrawn From Sale for Reasons of Safety or...

  8. 77 FR 77093 - Certain Computer Forensic Devices and Products Containing Same; Commission Determination Not To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-31

    ... Gaithersburg, Maryland. 76 FR 53695 (Aug. 29, 2011). The complaint alleges violations of section 337 of the... COMMISSION Certain Computer Forensic Devices and Products Containing Same; Commission Determination Not To... importation, and the sale within the United States after importation of certain computer forensic devices...

  9. 77 FR 5055 - Certain Liquid Crystal Display Devices and Products Containing the Same; Determination Not To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ... Samsung Electronics Co., Ltd. of Korea. 76 FR 39897 (Jul. 7, 2011). The complaint, as amended, alleges... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Liquid Crystal Display Devices and Products Containing the Same; Determination Not...

  10. 75 FR 71456 - Algonac Cast Products, Inc., Algonac, MI; Notice of Affirmative Determination Regarding...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-23

    ... Department's Notice of Determination was published in the Federal Register on October 8, 2010 (75 FR 62427... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration Algonac Cast Products, Inc., Algonac, MI; Notice of...

  11. 76 FR 69285 - Certain Game Devices, Components Thereof, and Products Containing the Same; Determination Not To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... Redmond, Washington (``Microsoft''). 76 FR 5206 (Jan. 28, 2011). The complaint alleged violations of... COMMISSION Certain Game Devices, Components Thereof, and Products Containing the Same; Determination Not To... for importation, and the sale within the United States after importation of certain game...

  12. 43 CFR 5040.5 - How does BLM determine and declare the annual productive capacity?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false How does BLM determine and declare the annual productive capacity? 5040.5 Section 5040.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR FOREST MANAGEMENT...

  13. 43 CFR 5040.5 - How does BLM determine and declare the annual productive capacity?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false How does BLM determine and declare the annual productive capacity? 5040.5 Section 5040.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR FOREST MANAGEMENT...

  14. 77 FR 39510 - Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Determination Not...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... COMMISSION Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Determination Not... the sale within the United States after importation of certain semiconductor integrated circuit... FR 25747-48 (May 1, 2012). The complaint alleges violations of section 337 of the Tariff Act of...

  15. Enhanced sea-ice export from the Arctic during the Younger Dryas.

    PubMed

    Not, Christelle; Hillaire-Marcel, Claude

    2012-01-01

    The Younger Dryas cold spell of the last deglaciation and related slowing of the Atlantic meridional overturning circulation have been linked to a large array of processes, notably an influx of fresh water into the North Atlantic related to partial drainage of glacial Lake Agassiz. Here we observe a major drainage event, in marine sediment cores raised from the Lomonosov Ridge, in the central Arctic Ocean marked by a pulse in detrital dolomitic-limestones. This points to an Arctic-Canadian sediment source area with about fivefold higher Younger Dryas ice-rafting deposition rate, in comparison with the Holocene. Our findings thus support the hypothesis of a glacial drainage event in the Canadian Arctic area, at the onset of the Younger Dryas, enhancing sea-ice production and drifting through the Arctic, then export through Fram Strait, towards Atlantic meridional overturning circulation sites of the northern North Atlantic. PMID:22337125

  16. Impact of Holocene climate variability on Arctic vegetation

    NASA Astrophysics Data System (ADS)

    Gajewski, K.

    2015-10-01

    This paper summarizes current knowledge about the postglacial history of the vegetation of the Canadian Arctic Archipelago (CAA) and Greenland. Available pollen data were used to understand the initial migration of taxa across the Arctic, how the plant biodiversity responded to Holocene climate variability, and how past climate variability affected primary production of the vegetation. Current evidence suggests that most of the flora arrived in the area during the Holocene from Europe or refugia south or west of the region immediately after local deglaciation, indicating rapid dispersal of propagules to the region from distant sources. There is some evidence of shrub species arriving later in Greenland, but it is not clear if this is dispersal limited or a response to past climates. Subsequent climate variability had little effect on biodiversity across the CAA, with some evidence of local extinctions in areas of Greenland in the late Holocene. The most significant impact of climate changes is on vegetation density and/or plant production.

  17. Stability-indicating spectrofluorometric method for the determination of some cephalosporin drugs via their degradation products.

    PubMed

    Mostafa, Nadia M; Abdel-Fattah, Laila; Weshahy, Soheir A; Hassan, Nagiba Y; Boltia, Shereen A

    2015-01-01

    A stability-indicating spectrofluorometric method was investigated for the determination of three cephalosporin drugs, namely, cefpodoxime proxetil (CPD), cefixime trihydrate (CFX), and cefepime hydrochloride (CPM), via their acid and alkali degradation products. The three drugs were determined via their acid degradation at 432, 422, and 435 nm using an excitation wavelength of 310, 330, and 307 nm for CPD, CFX, and CPM determination, respectively, and via their alkali degradation at 407, 411, and 405 nm using an excitation wavelength of 310, 305, and 297 nm for CPD, CFX, and CPM determination, respectively. Linearity was