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Sample records for alaskan north slope

  1. Thermal Properties of Alaskan North Slope Soils.

    Science.gov (United States)

    Overduin, P. P.; Kane, D. L.

    2002-12-01

    Climatic processes important to permafrost formation, maintenance and degradation have an annual to millennial timescale. The thin active layer, vegetation and snow above the permafrost can exert considerable influence on permafrost stability and react more rapidly than permafrost to climatic shifts. The thermal properties of this layer are thus important for the interpretation of permafrost data. We seek to predict bulk properties of a porous multiphase media based on state variables, bulk material properties and spatial phase densities. In this study, our objectives are: 1) to test thermal diffusivity probes in the field for the assessment of phase density, in particular of volumetric ice content and 2) to corroborate field studies with laboratory determinations of phase density and thermal diffusivity. We measure thermal properties and phase densities of a range of soils from the Alaskan North Slope, including high organic content and fine-grained mineral soils. Liquid water content is measured using time domain reflectometry to constrain the composition of the multiphase soil. Additional measurements of the soil's state are made using thermistors, heat flux plates and radial heat dissipation probes. The latter are thin films with embedded heat pulse wire and thermopiles to measure the radial thermal gradient response to temperature change. We report changes in thermal conductivity and diffusivity during freezing and thawing, and at different moisture contents and temperatures. The results for thermal conductivity and diffusivity as a function of phase density under field conditions are compared to those measured in the lab and to those calculated using empirical models.

  2. Alaskan North Slope Oil & Gas Transportation Support

    Energy Technology Data Exchange (ETDEWEB)

    Lilly, Michael Russell [Geo-Watersheds Scientific LLC, Fairbanks, AK (United States)

    2017-03-31

    North Slope oil and gas resources are a critical part of US energy supplies and their development is facing a period of new growth to meet increasing national energy needs. While this growth is taking place in areas active in development for more than 20 years, there are many increasing environmental challenges facing industry and management agencies. A majority of all exploration and development activities, pipeline maintenance and other field support activities take place in the middle of winter, when the fragile tundra surface is more stable. The window for the critical oil and gas winter operational season has been steadily decreasing over the last 25 years. The number of companies working on the North Slope is increasing. Many of these companies are smaller and working with fewer resources than the current major companies. The winter operations season starts with the tundra-travel opening, which requires 15 cm of snow on the land surface in the coastal management areas and 23 cm in the foothills management areas. All state managed areas require -5°C soil temperatures at a soil depth of 30 cm. Currently there are no methods to forecast this opening date, so field mobilization efforts are dependent on agency personnel visiting field sites to measure snow and soil temperature conditions. Weeks can be easily lost in the winter operating season due to delays in field verification of tundra conditions and the resulting mobilization. After the season is open, a significant percentage of exploration, construction, and maintenance do not proceed until ice roads and pads can be built. This effort is dependent on access to lake ice and under-ice water. Ice chipping is a common ice-road construction technique used to build faster and stronger ice roads. Seasonal variability in water availability and permitting approaches are a constant constraint to industry. At the end of the winter season, projects reliant on ice-road networks are often faced with ending operations

  3. Biocorrosive Thermophilic Microbial Communities in Alaskan North Slope Oil Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, Kathleen E.; Gieg, Lisa M.; Parisi, Victoria A.; Tanner, Ralph S.; Green Tringe, Susannah; Bristow, Jim; Suflita, Joseph M.

    2009-09-16

    Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon, with standard treatment methods targeting mesophilic sulfatereducing bacteria. In assessing biocorrosion potential at an Alaskan North Slope oil field, we identified thermophilic hydrogen-using methanogens, syntrophic bacteria, peptideand amino acid-fermenting bacteria, iron reducers, sulfur/thiosulfate-reducing bacteria and sulfate-reducing archaea. These microbes can stimulate metal corrosion through production of organic acids, CO2, sulfur species, and via hydrogen oxidation and iron reduction, implicating many more types of organisms than are currently targeted. Micromolar quantities of putative anaerobic metabolites of C1-C4 n-alkanes in pipeline fluids were detected, implying that these low molecular weight hydrocarbons, routinely injected into reservoirs for oil recovery purposes, are biodegraded and provide biocorrosive microbial communities with an important source of nutrients.

  4. Exporting Alaskan North Slope crude oil: Benefits and costs

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    The Department of Energy study examines the effects of lifting the current prohibitions against the export of Alaskan North Slope (ANS) crude. The study concludes that permitting exports would benefit the US economy. First, lifting the ban would expand the markets in which ANS oil can be sold, thereby increasing its value. ANS oil producers, the States of California and Alaska, and some of their local governments all would benefit from increased revenues. Permitting exports also would generate new economic activity and employment in California and Alaska. The study concludes that these economic benefits would be achieved without increasing gasoline prices (either in California or in the nation as a whole). Lifting the export ban could have important implications for US maritime interests. The Merchant Marine Act of 1970 (known as the Jones Act) requires all inter-coastal shipments to be carried on vessels that are US-owned, US-crewed, and US-built. By limiting the shipment of ANS crude to US ports only, the export ban creates jobs for the seafarers and the builders of Jones Act vessels. Because the Jones Act does not apply to exports, however, lifting the ban without also changing US maritime law would jeopardize the jobs associated with the current fleet of Jones Act tankers. Therefore the report analyzes selected economic impacts of several maritime policy alternatives, including: Maintaining current law, which allows foreign tankers to carry oil where export is allowed; requiring exports of ANS crude to be carried on Jones Act vessels; and requiring exports of ANS crude to be carried on vessels that are US-owned and US-crewed, but not necessarily US-built. Under each of these options, lifting the export ban would generate economic benefits.

  5. Exporting Alaskan North Slope crude oil: Benefits and costs

    International Nuclear Information System (INIS)

    1994-06-01

    The Department of Energy study examines the effects of lifting the current prohibitions against the export of Alaskan North Slope (ANS) crude. The study concludes that permitting exports would benefit the US economy. First, lifting the ban would expand the markets in which ANS oil can be sold, thereby increasing its value. ANS oil producers, the States of California and Alaska, and some of their local governments all would benefit from increased revenues. Permitting exports also would generate new economic activity and employment in California and Alaska. The study concludes that these economic benefits would be achieved without increasing gasoline prices (either in California or in the nation as a whole). Lifting the export ban could have important implications for US maritime interests. The Merchant Marine Act of 1970 (known as the Jones Act) requires all inter-coastal shipments to be carried on vessels that are US-owned, US-crewed, and US-built. By limiting the shipment of ANS crude to US ports only, the export ban creates jobs for the seafarers and the builders of Jones Act vessels. Because the Jones Act does not apply to exports, however, lifting the ban without also changing US maritime law would jeopardize the jobs associated with the current fleet of Jones Act tankers. Therefore the report analyzes selected economic impacts of several maritime policy alternatives, including: Maintaining current law, which allows foreign tankers to carry oil where export is allowed; requiring exports of ANS crude to be carried on Jones Act vessels; and requiring exports of ANS crude to be carried on vessels that are US-owned and US-crewed, but not necessarily US-built. Under each of these options, lifting the export ban would generate economic benefits

  6. STUDY OF TRANSPORTATION OF GTL PRODUCTS FROM ALASKAN NORTH SLOPE (ANS) TO MARKETS

    Energy Technology Data Exchange (ETDEWEB)

    Godwin A. Chukwu, Ph.D., P.E.

    2002-09-01

    The Alaskan North Slope is one of the largest hydrocarbon reserves in the US where Gas-to-Liquids (GTL) technology can be successfully implemented. The proven and recoverable reserves of conventional natural gas in the developed and undeveloped fields in the Alaskan North Slope (ANS) are estimated to be 38 trillion standard cubic feet (TCF) and estimates of additional undiscovered gas reserves in the Arctic field range from 64 TCF to 142 TCF. Transportation of the natural gas from the remote ANS is the key issue in effective utilization of this valuable and abundance resource. The throughput of oil through the Trans Alaska Pipeline System (TAPS) has been on decline and is expected to continue to decline in future. It is projected that by the year 2015, ANS crude oil production will decline to such a level that there will be a critical need for pumping additional liquid from GTL process to provide an adequate volume for economic operation of TAPS. The pumping of GTL products through TAPS will significantly increase its economic life. Transporting GTL products from the North Slope of Alaska down to the Marine terminal at Valdez is no doubt the great challenge facing the Gas to Liquids options of utilizing the abundant natural gas resource of the North Slope. The primary purpose of this study was to evaluate and assess the economic feasibility of transporting GTL products through the TAPS. Material testing program for GTL and GTL/Crude oil blends was designed and implemented for measurement of physical properties of GTL products. The measurement and evaluation of the properties of these materials were necessary so as to access the feasibility of transporting such materials through TAPS under cold arctic conditions. Results of the tests indicated a trend of increasing yield strength with increasing wax content. GTL samples exhibited high gel strengths at temperatures as high as 20 F, which makes it difficult for cold restart following winter shutdowns. Simplified

  7. Temperature and injection water source influence microbial community structure in four Alaskan North Slope hydrocarbon reservoirs.

    Directory of Open Access Journals (Sweden)

    Yvette Marisa Piceno

    2014-08-01

    Full Text Available A fundamental knowledge of microbial community structure in petroleum reservoirs can improve predictive modeling of these environments. We used hydrocarbon profiles, stable isotopes, and high-density DNA microarray analysis to characterize microbial communities in produced water from four Alaska North Slope hydrocarbon reservoirs. Produced fluids from Schrader Bluff (24-27°C, Kuparuk (47-70°C, Sag River (80°C, and Ivishak (80-83°C reservoirs were collected, with paired soured/non-soured wells sampled from Kuparuk and Ivishak. Chemical and stable isotope data suggested Schrader Bluff had substantial biogenic methane, whereas methane was mostly thermogenic in deeper reservoirs. Acetoclastic methanogens (Methanosaeta were most prominent in Schrader Bluff samples, and the combined δD and δ13C values of methane also indicated acetoclastic methanogenesis could be a primary route for biogenic methane. Conversely, hydrogenotrophic methanogens (e.g., Methanobacteriaceae and sulfide-producing Archaeoglobus and Thermococcus were more prominent in Kuparuk samples. Sulfide-producing microbes were detected in all reservoirs, uncoupled from souring status (e.g., the non-soured Kuparuk samples had higher relative abundances of many sulfate-reducers compared to the soured sample, suggesting sulfate-reducers may be living fermentatively/syntrophically when sulfate is limited. Sulfate abundance via long-term seawater injection resulted in greater relative abundances of Desulfonauticus, Desulfomicrobium, and Desulfuromonas in the soured Ivishak well compared to the non-soured well. In the non-soured Ivishak sample, several taxa affiliated with Thermoanaerobacter and Halomonas predominated. Archaea were not detected in the deepest reservoirs. Functional group taxa differed in relative abundance among reservoirs, likely reflecting differing thermal and/or geochemical influences.

  8. Wildlife response on the Alaska North Slope

    International Nuclear Information System (INIS)

    Costanzo, D.; McKenzie, B.

    1992-01-01

    Recognizing the need for a comprehensive plan to deal with potentially oiled wildlife on the Alaskan North Slope, a multifaceted wildlife protection strategy was developed and implemented during 1991. The strategy incorporated all aspects of wildlife response including protection of critical habitat, hazing, capture and stabilization, long term rehabilitation, and release. The primary wildlife response strategy emphasizes controlling of the release and spreading of spilled oil at the source to prevent or reduce contamination of potentially affected species and/or their habitat. A secondary response strategy concentrates on keeping potentially affected wildlife away from an oiled area through the use of deterrent techniques. Tertiary response involves the capture and treatment of oiled wildlife. Implementation of the strategy included the development of specialized training, the procurement of equipment, and the construction of a bird stabilization center. The result of this initiative is a comprehensive wildlife response capability on the Alaskan North Slope. 1 ref., 5 figs., 3 tabs

  9. A study of unstable slopes in permafrost areas : Alaskan case studies used as a training tool.

    Science.gov (United States)

    2011-12-01

    This report is the companion to the PowerPoint presentation for the project A Study of Unstable Slopes in Permafrost: Alaskan Case Studies Used as a Training Tool. The objectives of this study are 1) to provide a comprehensive review of literat...

  10. North Slope (Wahluke Slope) expedited response action cleanup plan

    International Nuclear Information System (INIS)

    1994-02-01

    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi 2 (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives

  11. North Slope (Wahluke Slope) expedited response action cleanup plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi{sup 2} (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives.

  12. North Slope, Alaska ESI: BIRDS (Bird Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for diving birds, gulls and terns, seabirds, shorebirds, and waterfowl for the North Slope of Alaska....

  13. North Slope, Alaska ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and freshwater fish species for the North Slope of Alaska. Vector...

  14. Winter chemistry of North Slope lakes

    Science.gov (United States)

    Chambers, M. K.; White, D. M.; Lilly, M. R.; Hinzman, L. D.; Hilton, K. M.; Busey, R.

    2006-12-01

    Lakes are important water resources on the North Slope of Alaska. Oilfield exploration and production requires water for facility use as well as transportation. Ice road construction requires winter extraction of fresh water. Since most North Slope lakes are relatively shallow, the quantity and quality of the water remaining under the ice by the end of the winter are important environmental management issues. Currently permits are based on the presence of overwintering fish populations and their sensitivity to low oxygen. Sampling during the winter of 2004 2005 sheds light on the winter chemistry of several pumped lakes and one unpumped lake on the North Slope. Dissolved oxygen, conductivity, pH, and temperature profiles were taken along with ice thickness and water depth measurements. Water samples were extracted and analyzed for Na, Ca, K, Mg, Fe, DOC, and alkalinity in the laboratory. Lake properties, rather than pumping activities, were the best predictors of oxygen depletion, with the highest levels of dissolved oxygen maintained in the lake with the least dissolved constituents. As would be expected, specific conductance increased with depth in the lake while dissolved oxygen decreased with depth. Dissolved oxygen and specific conductance data suggested that the lakes began to refresh in May. The summarized data provides a view of North Slope lake chemistry trends, while continued studies investigate the chemical impacts of pumping North Slope lakes through continued sampling and modeling efforts.

  15. Economics of Alaska North Slope gas utilization options

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, C.P.; Doughty, T.C.; Hackworth, J.H.; North, W.B.; Robertson, E.P.

    1996-08-01

    The recoverable natural gas available for sale in the developed and known undeveloped fields on the Alaskan North Slope (ANS) total about 26 trillion cubic feet (TCF), including 22 TCF in the Prudhoe Bay Unit (PBU) and 3 TCF in the undeveloped Point Thomson Unit (PTU). No significant commercial use has been made of this large natural gas resource because there are no facilities in place to transport this gas to current markets. To date the economics have not been favorable to support development of a gas transportation system. However, with the declining trend in ANS oil production, interest in development of this huge gas resource is rising, making it important for the U.S. Department of Energy, industry, and the State of Alaska to evaluate and assess the options for development of this vast gas resource. The purpose of this study was to assess whether gas-to-liquids (GTL) conversion technology would be an economic alternative for the development and sale of the large, remote, and currently unmarketable ANS natural gas resource, and to compare the long term economic impact of a GTL conversion option to that of the more frequently discussed natural gas pipeline/liquefied natural gas (LNG) option. The major components of the study are: an assessment of the ANS oil and gas resources; an analysis of conversion and transportation options; a review of natural gas, LNG, and selected oil product markets; and an economic analysis of the LNG and GTL gas sales options based on publicly available input needed for assumptions of the economic variables. Uncertainties in assumptions are evaluated by determining the sensitivity of project economics to changes in baseline economic variables.

  16. Economics of Alaska North Slope gas utilization options

    International Nuclear Information System (INIS)

    Thomas, C.P.; Doughty, T.C.; Hackworth, J.H.; North, W.B.; Robertson, E.P.

    1996-08-01

    The recoverable natural gas available for sale in the developed and known undeveloped fields on the Alaskan North Slope (ANS) total about 26 trillion cubic feet (TCF), including 22 TCF in the Prudhoe Bay Unit (PBU) and 3 TCF in the undeveloped Point Thomson Unit (PTU). No significant commercial use has been made of this large natural gas resource because there are no facilities in place to transport this gas to current markets. To date the economics have not been favorable to support development of a gas transportation system. However, with the declining trend in ANS oil production, interest in development of this huge gas resource is rising, making it important for the U.S. Department of Energy, industry, and the State of Alaska to evaluate and assess the options for development of this vast gas resource. The purpose of this study was to assess whether gas-to-liquids (GTL) conversion technology would be an economic alternative for the development and sale of the large, remote, and currently unmarketable ANS natural gas resource, and to compare the long term economic impact of a GTL conversion option to that of the more frequently discussed natural gas pipeline/liquefied natural gas (LNG) option. The major components of the study are: an assessment of the ANS oil and gas resources; an analysis of conversion and transportation options; a review of natural gas, LNG, and selected oil product markets; and an economic analysis of the LNG and GTL gas sales options based on publicly available input needed for assumptions of the economic variables. Uncertainties in assumptions are evaluated by determining the sensitivity of project economics to changes in baseline economic variables

  17. Dinosaurs on the North Slope, Alaska: High latitude, latest cretaceous environments

    Science.gov (United States)

    Brouwers, E.M.; Clemens, W.A.; Spicer, R.A.; Ager, T.A.; Carter, L.D.; Sliter, W.V.

    1987-01-01

    Abundant skeletal remains demonstrate that lambeosaurine hadrosaurid, tyrannosaurid, and troodontid dinosaurs lived on the Alaskan North Slope during late Campanian-early Maestrichtian time (about 66 to 76 million years ago) in a deltaic environment dominated by herbaceous vegetation. The high ground terrestrial plant community was a mild- to cold-temperate forest composed of coniferous and broad leaf trees. The high paleolatitude (about 70?? to 85?? North) implies extreme seasonal variation in solar insolation, temperature, and herbivore food supply. Great distances of migration to contemporaneous evergreen floras and the presence of both juvenile and adult hadrosaurs suggest that they remained at high latitudes year-round. This challenges the hypothesis that short-term periods of darkness and temperature decrease resulting from a bolide impact caused dinosaurian extinction.

  18. US North Slope gas and Asian LNG markets

    Science.gov (United States)

    Attanasi, E.D.

    1994-01-01

    Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology. ?? 1995.

  19. The North Slope of Alaska and Tourism: Potential Impacts on the Arctic National Wildlife Refuge (ANWR)

    Science.gov (United States)

    Everett, L. R.

    2004-12-01

    The hydrocarbon industry of Alaska is currently the leading producer of revenue for the Alaskan state economy. Second only to hydrocarbons is the tourism industry. Tourism has been a viable industry since the 1890's when cruises touted the beauty of glaciers and icebergs along the Alaskan coastline. This industry has seen a steady growth for the past few decades throughout the state. The North Slope of Alaska, particularly Prudhoe Bay and the National Petroleum Reserve, has long been associated with hydrocarbon development and today displays a landscape dotted with gravel drill pads, gas and oil pipelines and housing for the oil workers. While tourism is not usually considered hand in hand with the hydrocarbon industry, it has mimicked the development of hydrocarbons almost since the beginning. Today one not only sees the effects of the oil industry on the North Slope, but also the tourist industry as planes unload dozens of tourists, or tour buses and private vehicles arrive daily via the Dalton Highway. In Deadhorse, hotels that once only housed the oil workers now welcome the tourist, offering tours of the oil fields and adjacent areas and have become jumping off sites for wilderness trips. Tourism will create jobs as well as revenue. However, at present, there are few restrictions or guidelines in place that will deal with the potential impacts of increased tourism. Because of this there are many concerns about the possible impacts tourism and the infrastructure development will have on the North Slope. To list several concerns: (1) What are the impacts of increased tourism and the infrastructure development? (2) What will the impacts be on the Arctic National Wildlife Refuge (ANWR), which sits a mere 60 miles to the east of Deadhorse? (3) Will hydrocarbon development in ANWR and the associated infrastructure exacerbate potential impact by encouraging greater use of the Refuge by tourists? (4) Will tourism itself have a negative impact on this fragile

  20. North Slope, Alaska ESI: T_MAMMAL (Terrestrial Mammal Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for brown bears, caribou, and muskoxen for the North Slope, Alaska. Vector polygons in this data set...

  1. North Slope, Alaska ESI: M_MAMMAL (Marine Mammal Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for whales, seals, walruses, and polar bears for the North Slope of Alaska. Vector polygons in this data...

  2. The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

    Directory of Open Access Journals (Sweden)

    J. M. Creamean

    2018-01-01

    Full Text Available The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM program's Fifth Airborne Carbon Measurements (ACME-V field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

  3. The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

    Science.gov (United States)

    Creamean, Jessie M.; Maahn, Maximilian; de Boer, Gijs; McComiskey, Allison; Sedlacek, Arthur J.; Feng, Yan

    2018-01-01

    The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

  4. North Slope Decision Support for Water Resource Planning and Management

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, William; Brumbelow, Kelly

    2013-03-31

    The objective of this project was to enhance the water resource decision-making process with respect to oil and gas exploration/production activities on Alaska’s North Slope. To this end, a web-based software tool was developed to allow stakeholders to assemble, evaluate, and communicate relevant information between and amongst themselves. The software, termed North Slope Decision Support System (NSDSS), is a visually-referenced database that provides a platform for running complex natural system, planning, and optimization models. The NSDSS design was based upon community input garnered during a series of stakeholder workshops, and the end product software is freely available to all stakeholders via the project website. The tool now resides on servers hosted by the UAF Water and Environmental Research Center, and will remain accessible and free-of-charge for all interested stakeholders. The development of the tool fostered new advances in the area of data evaluation and decision support technologies, and the finished product is envisioned to enhance water resource planning activities on Alaska’s North Slope.

  5. Constraining seasonal active layer dynamics and chemical weathering reactions occurring in North Slope Alaskan watersheds with major ion and isotope (δ34SSO4, δ13CDIC, 87Sr/86Sr, δ44/40Ca, and δ44/42Ca) measurements

    Science.gov (United States)

    Lehn, Gregory O.; Jacobson, A. D.; Douglas, T. A.; McClelland, J. W.; Barker, A. J.; Khosh, M. S.

    2017-11-01

    Rising air temperatures in the Arctic may destabilize a large pool of organic carbon stored in permafrost, thereby causing a positive feedback to global climate warming. Permafrost thaw could also deepen hydrologic flow paths and expose previously frozen rock and mineral fragments to chemical weathering. Future shifts in the inorganic solute geochemistry of Arctic rivers may signal changes in soil processes that also affect organic carbon storage. Tracing permafrost thaw with dissolved riverine loads requires understanding the spatial and seasonal variation of chemical weathering reactions and other biogeochemical phenomena that affect elemental mass-transport. To help identify connections between mineral weathering and active layer processes, we studied the major ion and isotope (δ34SSO4, δ13CDIC, 87Sr/86Sr, δ44/40Ca, and δ44/42Ca) geochemistry of five streams draining the North Slope of Alaska. Continuous permafrost underlies all streams, but the Atigun River, Roche Moutonnée Creek, and Trevor Creek primarily drain bare bedrock outcrops in the Brooks Range, while the Upper Kuparuk River and Imnavait Creek primarily drain tundra. In total, we collected 546 water samples spanning the spring freshet through fall freeze-up in 2009 and 2010. We also analyzed snow, rock, sediment, soil, and plant samples. Major ion ratios and δ13CDIC values point to the overall dominance of carbonate weathering by carbonic and sulfuric acids, with additional influences from atmospheric deposition, plant decay, sulfate salt dissolution, and silicate weathering by carbonic acid. δ13CDIC values may also reflect partial equilibration with soil and atmospheric CO2. All streams display large seasonal variations in major ion ratios and δ13CDIC values that are consistent with progressive deepening of the seasonally thawed zone over the summer. In the mountain watersheds, carbonate weathering dominates during the spring and summer, while sulfate salt (primarily CaSO4 and MgSO4

  6. Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: south slope versus north slope

    Directory of Open Access Journals (Sweden)

    C. Chen

    2018-01-01

    Full Text Available Nitrogen cycling is tightly associated with environment. The south slope of a given mountain could significantly differ from north slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and Δδ15Nleaf-soil (Δδ15Nleaf-soil =  leaf δ15N − soil δ15N could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and Δδ15Nleaf-soil should differ between the two slopes. However, such a comparative study between two slopes has never been conducted. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from those on a regional scale. This led to our argument that environmental effects on leaf and soil δ15N could depend on local environment. To confirm our hypothesis and argument, we measured leaf and soil δ15N on the south and north slopes of Tian Shan. Remarkable environmental differences between the two slopes provided an ideal opportunity for our test. The study showed that leaf δ15N, soil δ15N and δ15Nleaf-soil on the south slope were greater than those on the north slope, although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the south slope has higher soil N transformation rates and soil N availability than the north slope. In addition, in this study it was observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C ∕ N, soil moisture and silt ∕ clay ratio on the north slope, whereas on the south slope only leaf C ∕ N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation, soil moisture and silt ∕ clay ratio on the north slope, whereas on the south slope, mean annual precipitation and soil moisture exerted significant effects. Precipitation exerted contrary effects on soil

  7. Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: south slope versus north slope

    Science.gov (United States)

    Chen, Chongjuan; Jia, Yufu; Chen, Yuzhen; Mehmood, Imran; Fang, Yunting; Wang, Guoan

    2018-01-01

    Nitrogen cycling is tightly associated with environment. The south slope of a given mountain could significantly differ from north slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and Δδ15Nleaf-soil (Δδ15Nleaf-soil = leaf δ15N - soil δ15N) could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and Δδ15Nleaf-soil should differ between the two slopes. However, such a comparative study between two slopes has never been conducted. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from those on a regional scale. This led to our argument that environmental effects on leaf and soil δ15N could depend on local environment. To confirm our hypothesis and argument, we measured leaf and soil δ15N on the south and north slopes of Tian Shan. Remarkable environmental differences between the two slopes provided an ideal opportunity for our test. The study showed that leaf δ15N, soil δ15N and δ15Nleaf-soil on the south slope were greater than those on the north slope, although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the south slope has higher soil N transformation rates and soil N availability than the north slope. In addition, in this study it was observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C / N, soil moisture and silt / clay ratio on the north slope, whereas on the south slope only leaf C / N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation, soil moisture and silt / clay ratio on the north slope, whereas on the south slope, mean annual precipitation and soil moisture exerted significant effects. Precipitation exerted contrary effects on soil δ15N between the two slopes. Thus, this study

  8. Processes Influencing Ozone Levels in Alaskan Forest Fires Plumes during Long-Range Transport over the North Atlantic

    Science.gov (United States)

    Real, E.; Law, K. S.; Wienzierl, B.; Fiebig, M.; Petzold, A.; Wild, O.; Methven, J.; Arnold, S.; Stohl, A.; Huntrieser, H.; hide

    2006-01-01

    A case of long-range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by 3 different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy, mainly in form of PAN. Observed O3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, is used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data, and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume is investigated using in-situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast-J), run in the model. Significant impacts on photochemistry are found with a decrease of 18 percent in O3 production and 24 percent in O3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O3 increases attributed primarily to PAN decomposition during descent of the plume towards Europe. The predicted O3 changes are very dependent on temperature changes during transport, and also, on water vapor levels in the lower troposphere which can lead to O3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutants level in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales (averaging 6.25 days) were derived from CO changes. Observed and simulated O3/CO correlations in the plume are also compared in order to evaluate the photochemistry in the model. Observed slopes changed from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is

  9. Evaluation of Wax Deposition and Its Control During Production of Alaska North Slope Oils

    Energy Technology Data Exchange (ETDEWEB)

    Tao Zhu; Jack A. Walker; J. Liang

    2008-12-31

    Due to increasing oil demand, oil companies are moving into arctic environments and deep-water areas for oil production. In these regions of lower temperatures, wax deposits begin to form when the temperature in the wellbore falls below wax appearance temperature (WAT). This condition leads to reduced production rates and larger pressure drops. Wax problems in production wells are very costly due to production down time for removal of wax. Therefore, it is necessary to develop a solution to wax deposition. In order to develop a solution to wax deposition, it is essential to characterize the crude oil and study phase behavior properties. The main objective of this project was to characterize Alaskan North Slope crude oil and study the phase behavior, which was further used to develop a dynamic wax deposition model. This report summarizes the results of the various experimental studies. The subtasks completed during this study include measurement of density, molecular weight, viscosity, pour point, wax appearance temperature, wax content, rate of wax deposition using cold finger, compositional characterization of crude oil and wax obtained from wax content, gas-oil ratio, and phase behavior experiments including constant composition expansion and differential liberation. Also, included in this report is the development of a thermodynamic model to predict wax precipitation. From the experimental study of wax appearance temperature, it was found that wax can start to precipitate at temperatures as high as 40.6 C. The WAT obtained from cross-polar microscopy and viscometry was compared, and it was discovered that WAT from viscometry is overestimated. From the pour point experiment it was found that crude oil can cease to flow at a temperature of 12 C. From the experimental results of wax content, it is evident that the wax content in Alaskan North Slope crude oil can be as high as 28.57%. The highest gas-oil ratio for a live oil sample was observed to be 619.26 SCF

  10. CARVE-ARCSS: Methane Loss From Arctic- Fluxes From the Alaskan North Slope, 2012-2014

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the results of (1) year-round measurements of methane (CH4) flux along with soil and air temperatures at five eddy covariance towers at sites...

  11. DEVELOPMENT OF SHALLOW VISCOUS OIL RESERVES IN NORTH SLOPE

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2004-12-01

    North Slope of Alaska has huge oil deposits in heavy oil reservoirs such as Ugnu, West Sak and Shrader Bluff etc. The viscosity of the last two reservoir oils vary from {approx}30 cp to {approx}3000 cp and the amount in the range of 10-20 billion barrels. High oil viscosity and low formation strength impose problems to high recovery and well productivity. Water-alternate-gas injection processes can be effective for the lower viscosity end of these deposits in West Sak and Shrader Bluff. Several gas streams are available in the North Slope containing NGL and CO{sub 2} (a greenhouse gas). The goal of this research is to develop tools to find optimum solvent, injection schedule and well-architecture for a WAG process in North Slope shallow sand viscous oil reservoirs. Coreflood, quarter 5-spot study, compositional simulation, wettability, relative permeability study and streamline-based simulation were conducted in this project. 1D compositional simulation results agree reasonably well with those of the slim tube experiments. Injection of CO{sub 2}-NGL is preferable over that of PBG-NGL. MME is sensitive to pressure (in the range of 1300-1800 psi) for the injection of PBG-NGL, but not for CO{sub 2}-NGL. Three hydrocarbon phases form in this pressure range. As the mean thickness of the adsorbed organic layer on minerals increases, the oil-water contact angle increases. The adsorbed organic films left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion for minerals aged with just the asphaltene fraction is similar to that of the whole oil implying that asphaltenes are responsible for the mixed-wettability in this reservoir. A new relative permeability model for a four-phase, mixed-wet system has been proposed. A streamline module is developed which can be incorporated in an existing finite-difference based

  12. Alaska North Slope regional gas hydrate production modeling forecasts

    Science.gov (United States)

    Wilson, S.J.; Hunter, R.B.; Collett, T.S.; Hancock, S.; Boswell, R.; Anderson, B.J.

    2011-01-01

    A series of gas hydrate development scenarios were created to assess the range of outcomes predicted for the possible development of the "Eileen" gas hydrate accumulation, North Slope, Alaska. Production forecasts for the "reference case" were built using the 2002 Mallik production tests, mechanistic simulation, and geologic studies conducted by the US Geological Survey. Three additional scenarios were considered: A "downside-scenario" which fails to identify viable production, an "upside-scenario" describes results that are better than expected. To capture the full range of possible outcomes and balance the downside case, an "extreme upside scenario" assumes each well is exceptionally productive.Starting with a representative type-well simulation forecasts, field development timing is applied and the sum of individual well forecasts creating the field-wide production forecast. This technique is commonly used to schedule large-scale resource plays where drilling schedules are complex and production forecasts must account for many changing parameters. The complementary forecasts of rig count, capital investment, and cash flow can be used in a pre-appraisal assessment of potential commercial viability.Since no significant gas sales are currently possible on the North Slope of Alaska, typical parameters were used to create downside, reference, and upside case forecasts that predict from 0 to 71??BM3 (2.5??tcf) of gas may be produced in 20 years and nearly 283??BM3 (10??tcf) ultimate recovery after 100 years.Outlining a range of possible outcomes enables decision makers to visualize the pace and milestones that will be required to evaluate gas hydrate resource development in the Eileen accumulation. Critical values of peak production rate, time to meaningful production volumes, and investments required to rule out a downside case are provided. Upside cases identify potential if both depressurization and thermal stimulation yield positive results. An "extreme upside

  13. Estimated prospective tanker rates for Alaska North Slope crude oil

    International Nuclear Information System (INIS)

    Marks, Roger

    1992-01-01

    Within the next ten years, three significant events will affect the structure of tankering costs for the Alaska North Slope (ANS) oil fields. These are: the double hulling requirement of the Oil Spill Pollution Act of 1990 (OPA90); the ageing of the tanker fleet; and the decline in ANS and West Coast oil production, which will eliminate more costly shipments to the Gulf Coast. The purpose of this paper is to estimate how these will affect tankering costs over the next twenty years. As baseline, the existing fleet is described, followed by a detailed discussion of the above factors. Company specific shipping requirements are calculated as compared to ship-by-ship tonnage availability (based on the current fleet) pursuant to these events, and the resultant tonnage deficit. A model is presented that derives a hypothetical reconstruction scheme to eliminate the deficits on a company specific ship-by-ship basis. The resulting costs are then translated into a weighted average per barrel ANS cost. The specific double hull costs are segregated. (author)

  14. Site Scientist for the North Slope of Alaska Site

    Energy Technology Data Exchange (ETDEWEB)

    Verlinde, Johannes [Pennsylvania State Univ., State College, PA (United States)

    2016-03-11

    Under this grant our team contributed scientific support to the Department of Energy Atmospheric Radiation Program’s (DOE-ARM) Infrastructure team to maintain high quality research data at the DOE-ARM North Slope of Alaska with special emphasis on the radars. Under our guidance two major field campaigns focusing on mixed-phase Arctic clouds were conducted that greatly increased the community’s understanding of the many processes working together to control the evolution of single-layer cloud mixed-phase clouds. A series of modeling and observational studies revealed that the longevity of the radiatively important liquid phase is strongly dependent on how the ice phase develops in mixed-phase clouds. A new ice microphysics parameterization was developed to capture better the natural evolution of ice particle growth in evolving environments. An ice particle scattering database was developed for all ARM radar frequencies. This database was used in a radar simulator (Doppler spectrum and polarimetric variables) to aid in the interpretation of the advanced ARM radars. At the conclusion of this project our team was poised to develop a complete radar simulator consistent with the new microphysical parameterization, taking advantage of parameterization’s advanced characterization of the ice shape and ice density.

  15. Commercial possibilities for stranded conventional gas from Alaska's North Slope

    Science.gov (United States)

    Attanasi, E.D.; Freeman, P.A.

    2014-01-01

    Stranded gas resources are defined for this study as gas resources in discrete accumulations that are not currently commercially producible, or producible at full potential, for either physical or economic reasons. Approximately 35 trillion cubic feet (TCF) of stranded gas was identified on Alaska’s North Slope. The commercialization of this resource requires facilities to transport gas to markets where sales revenue will be sufficient to offset the cost of constructing and operating a gas delivery system. With the advent of the shale gas revolution, plans for a gas pipeline to the conterminous US have been shelved (at least temporarily) and the State and resource owners are considering a liquefied natural gas (LNG) export project that targets Asian markets. This paper focuses on competitive conditions for Asian gas import markets by estimating delivered costs of competing supplies from central Asia, Russia, Indonesia, Malaysia, and Australia in the context of a range of import gas demand projections for the period from 2020 to 2040. These suppliers’ costs are based on the cost of developing, producing, and delivering to markets tranches of the nearly 600 TCF of recoverable gas from their own conventional stranded gas fields. The results of these analyses imply that Alaska’s gas exports to Asia will likely encounter substantial competitive challenges. The sustainability of Asia’s oil-indexed LNG pricing is also discussed in light of a potentially intense level of competition.

  16. Potential water yield response following clearcut harvesting on north and south slopes in northern Idaho

    Science.gov (United States)

    Richard G. Cline; Harold F. Haupt; Gaylon S. Campbell

    1977-01-01

    The hydrologic response of small clearcuts on north and south slopes in northern Idaho was investigated. On the north slope, substantial gains (27 to 35 cm) in potential water yield per year resulted from (a) removal of transpiring surfaces associated with plant cover, (b) elimination of snow interception by a closed-canopied forest, and (C) delayed reoccupation of the...

  17. 75 FR 79017 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel

    Science.gov (United States)

    2010-12-17

    .... Update on the project tracking system, database and public Web site. NSSI priority recommendations on... Bureau of Land Management Notice of Public Meeting, North Slope Science Initiative--Science Technical Advisory Panel AGENCY: Bureau of Land Management, Alaska State Office, North Slope Science Initiative...

  18. NACP Woody Vegetation Characteristics of 1,039 Sites across North Slope, Alaska, V2

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the results of (1) field measurements of woody vegetation (shrubs) at 26 diverse sites across the North Slope of Alaska during 2010 and 2011,...

  19. NACP Woody Vegetation Characteristics of 1,039 Sites across the North Slope, Alaska

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the results of (1) field measurements of woody vegetation (shrubs) at 26 diverse sites across the North Slope of Alaska during 2010 and 2011,...

  20. Final Scientific/Technical Report of Gas Hydrate Dynamics on the Alaskan Beaufort Continental Slope: Modeling and Field Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Hornbach, Matthew J [Southern Methodist Univ., Dallas, TX (United States); Colwell, Frederick S [Oregon State Univ., Corvallis, OR (United States); Harris, Robert [Oregon State Univ., Corvallis, OR (United States)

    2017-07-06

    Methane Hydrates, a solid form of methane and water, exist at high pressures and low temperatures, occurs on every continental margin on Earth, represents one of the largest reservoirs of carbon on the planet, and, if destabilized, may play an important role in both slope stability and climate change. For decades, researchers have studied methane hydrates with the hope of determining if methane hydrates are destabilizing, and if so, how this destabilization might impact slope stability and ocean/atmosphere carbon budgets. In the past ~5 years, it has become well established that the upper “feather-edge” of methane hydrate stability (intermediate water depths of ~200-500 meters below sea level) represents an important frontier for methane hydrates stability research, as this zone is most susceptible to destabilization due to minor fluctuations in ocean temperature in space and time. The Arctic Ocean—one of the fastest warming regions on Earth—is perhaps the best place to study possible changes to methane hydrate stability due to ocean warming. To address the stability of methane hydrates at intermediate ocean depths, Southern Methodist University in partnership with Oregon State University and The United State Geological Survey at Woods Hole began investigating methane hydrate stability in intermediate water depths below both the US Beaufort Sea and the Atlantic Margin, from 2012-2017. The work was funded by the Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). The key goal of the SMU component of this study was to collect the first ever heat flow data in the Beaufort Sea and compare measured shallow (probe-based1) heat flow values with deeper (BSR-derived2) heat flow values, and from this, determine whether hydrates were in thermal equilibrium. In September 2016, SMU/OSU collected the first ever heat flow measurements in the US Beaufort Sea. Despite poor weather and rough seas, the cruise was a success, with 116 heat flow

  1. Alaska North Slope Tundra Travel Model and Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Harry R. Bader; Jacynthe Guimond

    2006-03-01

    The Alaska Department of Natural Resources (DNR), Division of Mining, Land, and Water manages cross-country travel, typically associated with hydrocarbon exploration and development, on Alaska's arctic North Slope. This project is intended to provide natural resource managers with objective, quantitative data to assist decision making regarding opening of the tundra to cross-country travel. DNR designed standardized, controlled field trials, with baseline data, to investigate the relationships present between winter exploration vehicle treatments and the independent variables of ground hardness, snow depth, and snow slab thickness, as they relate to the dependent variables of active layer depth, soil moisture, and photosynthetically active radiation (a proxy for plant disturbance). Changes in the dependent variables were used as indicators of tundra disturbance. Two main tundra community types were studied: Coastal Plain (wet graminoid/moist sedge shrub) and Foothills (tussock). DNR constructed four models to address physical soil properties: two models for each main community type, one predicting change in depth of active layer and a second predicting change in soil moisture. DNR also investigated the limited potential management utility in using soil temperature, the amount of photosynthetically active radiation (PAR) absorbed by plants, and changes in microphotography as tools for the identification of disturbance in the field. DNR operated under the assumption that changes in the abiotic factors of active layer depth and soil moisture drive alteration in tundra vegetation structure and composition. Statistically significant differences in depth of active layer, soil moisture at a 15 cm depth, soil temperature at a 15 cm depth, and the absorption of photosynthetically active radiation were found among treatment cells and among treatment types. The models were unable to thoroughly investigate the interacting role between snow depth and disturbance due to a

  2. 78 FR 55754 - Second Call for Nominations: North Slope Science Initiative, Science Technical Advisory Panel

    Science.gov (United States)

    2013-09-11

    ..., marine biology, landscape ecology, and climatology. Duties of the Science Technical Advisory Panel are... Service, National Park Service, Bureau of Ocean Energy Management and National Marine Fisheries Service... needed for the management of resources on the North Slope of Alaska and the adjacent marine environment...

  3. 78 FR 38358 - Call for Nominations: North Slope Science Initiative, Science Technical Advisory Panel, Alaska

    Science.gov (United States)

    2013-06-26

    ..., marine biology, landscape ecology, and climatology. Duties of the Science Technical Advisory Panel are... Energy Management and National Marine Fisheries Service; the Bureau of Land Management Alaska State... needed for the management of resources on the North Slope of Alaska and the adjacent marine environment...

  4. Direct solar radiation on various slopes from 0 to 60 degrees north latitude.

    Science.gov (United States)

    John Buffo; Leo J. Fritschen; James L. Murphy

    1972-01-01

    Direct beam solar radiation is presented in graphical and tabular form for hourly, daily, and yearly values for seven slopes on each of 16 aspects from the Equator to 60 degrees north in 10-degree increments. Theoretical equations necessary for the calculations are given. Solar altitude and azimuth during the day and year are also presented for the same latitude.

  5. Fire behavior, weather, and burn severity of the 2007 Anaktuvuk River tundra fire, North Slope, Alaska

    Science.gov (United States)

    Benjamin M. Jones; Crystal A. Kolden; Randi Jandt; John T. Abatzoglu; Frank Urban; Christopher D. Arp

    2009-01-01

    In 2007, the Anaktuvuk River Fire (ARF) became the largest recorded tundra fire on the North Slope of Alaska. The ARF burned for nearly three months, consuming more than 100,000 ha. At its peak in early September, the ARF burned at a rate of 7000 ha d-1. The conditions potentially responsible for this large tundra fire include modeled record high...

  6. Economics of Undiscovered Oil and Gas in the North Slope of Alaska: Economic Update and Synthesis

    Science.gov (United States)

    Attanasi, E.D.; Freeman, P.A.

    2009-01-01

    The U.S. Geological Survey (USGS) has published assessments by geologists of undiscovered conventional oil and gas accumulations in the North Slope of Alaska; these assessments contain a set of scientifically based estimates of undiscovered, technically recoverable quantities of oil and gas in discrete oil and gas accumulations that can be produced with conventional recovery technology. The assessments do not incorporate economic factors such as recovery costs and product prices. The assessors considered undiscovered conventional oil and gas resources in four areas of the North Slope: (1) the central North Slope, (2) the National Petroleum Reserve in Alaska (NPRA), (3) the 1002 Area of the Arctic National Wildlife Refuge (ANWR), and (4) the area west of the NPRA, called in this report the 'western North Slope'. These analyses were prepared at different times with various minimum assessed oil and gas accumulation sizes and with slightly different assumptions. Results of these past studies were recently supplemented with information by the assessment geologists that allowed adjustments for uniform minimum assessed accumulation sizes and a consistent set of assumptions. The effort permitted the statistical aggregation of the assessments of the four areas composing the study area. This economic analysis is based on undiscovered assessed accumulation distributions represented by the four-area aggregation and incorporates updates of costs and technological and fiscal assumptions used in the initial economic analysis that accompanied the geologic assessment of each study area.

  7. 2000 Yukon North Slope conference : The challenge of change : Summary report

    International Nuclear Information System (INIS)

    2001-01-01

    The proclamation of the Inuvialuit Final Agreement (IFA) took place in 1984, and the protection of the environment of the Yukon North Slope was ensured through new mechanisms provided in the Agreement. The creation of Ivvavik National Park and Herschel Island Territorial Park resulted from section 12 of the Agreement, as well as the Wildlife Management Advisory Council (North Slope). Designated as having a special conservation regime with protection of wildlife, habitat and traditional native use, the entire Yukon North Slope is of paramount importance. Promoting discussion among native organizations, government and the private sector is one of the mandates of the new management regime, under section 12(57) of the IFA. These discussions must deal with management coordination for the North Slope. The sixth Yukon North Slope Conference was held in September 2000, and this document summarizes the proceedings. The document was based on transcripts and reports from workshops held during the conference. In some instances, the material was edited for clarification. Approximately 100 delegates represented various interests ranging from academia to wildlife conservation organizations, from government to native organizations and others. The discussions included topics as varied as oil and gas development, climate change, ecological monitoring, wildlife populations, tourism development, implementation of the IFA, environmental assessment, and protected areas. Some of the recommendations emanating from the conference touched information dissemination on climate change and ecological monitoring, the establishment of a roundtable representing all stakeholders concerning environmental assessments for oil and gas development, and continued support for natives to maintain their cultural values and traditional uses among others. figs., 5 appendices

  8. Impact of Alaskan gas subsidy

    International Nuclear Information System (INIS)

    George, R.R.

    2002-01-01

    This report provides the Government of the Northwest Territories (GNWT) with an assessment of the impact of the Alaska natural gas tax credit proposed and passed in the United States Senate energy bill. In particular, Purvin and Gertz evaluated the impact of the Alaskan gas subsidy on potential Mackenzie Delta/Beaufort Sea production as well as existing and future production from other areas including Western Canada, the Rocky Mountains in the United States, and the Gulf Coast. The mechanisms through which other producing areas are affected were described and the typical volumetric impact is presented using gas models developed by Purvin and Gertz. The GNWT wants to maximize the benefits of Arctic gas development for its constituents but believes that its interests will be negatively impacted by subsidized Alaskan gas which will be applied for the period beginning in 2010. The tax credit sets a floor price of $3.25 (US)/MMBtu. Purvin and Gertz concludes that the Alaskan gas subsidy would produce a misallocation of resources and distort the continental North American natural gas market. It would encourage over investment in Alaskan gas production because the credit works as a false signal to the privileged few that divert resources from higher value activities to lower value activities. The winners of the Alaskan gas subsidy would be Alaskan producers and the Alaskan economy. The losers would be other resource owners, producers, and American taxpayers because they would finance the subsidy through a tax credit mechanism. There would be an overall loss to the economy because of sub-optimal allocation of resources. In addition, producers in existing producing areas such as the Mackenzie Delta/Beaufort Sea region would face lower market prices as a result of the subsidy, thereby reducing their investments. It was concluded that the Alaskan gas subsidy is counterproductive from the perspective of a secure continental supply of natural gas. 1 tab., 2 figs

  9. Identification of unrecognized tundra fire events on the north slope of Alaska

    Science.gov (United States)

    Jones, Benjamin M.; Breen, Amy L.; Gaglioti, Benjamin V.; Mann, Daniel H.; Rocha, Adrian V.; Grosse, Guido; Arp, Christopher D.; Kunz, Michael L.; Walker, Donald A.

    2013-01-01

    Characteristics of the natural fire regime are poorly resolved in the Arctic, even though fire may play an important role cycling carbon stored in tundra vegetation and soils to the atmosphere. In the course of studying vegetation and permafrost-terrain characteristics along a chronosequence of tundra burn sites from AD 1977, 1993, and 2007 on the North Slope of Alaska, we discovered two large, previously unrecognized tundra fires. The Meade River fire burned an estimated 500 km2 and the Ketik River fire burned an estimated 1200 km2. Based on radiocarbon dating of charred twigs, analysis of historic aerial photography, and regional climate proxy data, these fires likely occurred between AD 1880 and 1920. Together, these events double the estimated burn area on the North Slope of Alaska over the last ~100 to 130 years. Assessment of vegetation succession along the century-scale chronosequence of tundra fire disturbances demonstrates for the first time on the North Slope of Alaska that tundra fires can facilitate the invasion of tundra by shrubs. Degradation of ice-rich permafrost was also evident at the fire sites and likely aided in the presumed changes of the tundra vegetation postfire. Other previously unrecognized tundra fire events likely exist in Alaska and other Arctic regions and identification of these sites is important for better understanding disturbance regimes and carbon cycling in Arctic tundra.

  10. Glacially-derived overpressure in the northeastern Alaskan subduction zone: combined tomographic and morphometric analysis of shallow sediments on the Yakutat shelf and slope, Gulf of Alaska

    Science.gov (United States)

    Clary, W. A.; Worthington, L. L.; Scuderi, L. A.; Daigle, H.; Swartz, J. M.

    2017-12-01

    The Pamplona zone fold and thrust belt is the offshore expression of convergence and shallow subduction of the Yakutat microplate beneath North America in the northeastern Alaska subduction zone. The combination of convergent tectonics and glaciomarine sedimentary processes create patterns of deformation and deposition resulting in a shallow sedimentary sequence with varying compaction, fluid pressure, and fault activity. We propose that velocity variations observed in our tomographic analysis represent long-lived fluid overpressure due to loading by ice sheets and sediments. Regions with bathymetric and stratigraphic evidence of recent ice sheets and associated sedimentation should be collocated with evidence of overpressure (seismic low velocity zones) in the shallow sediments. Here, we compare a velocity model with shelf seismic stratigraphic facies and modern seafloor morphology. To document glacially derived morphology we use high resolution bathymetry to identify channel and gully networks on the western Yakutat shelf-slope then analyze cross-channel shape indices across the study area. We use channel shape index measurements as a proxy of recent ice-proximal sedimentation based on previously published results that proposed a close correlation. Profiles taken at many locations were fitted with a power function and assigned a shape - U-shape channels likely formed proximal to recent ice advances. Detailed velocity models were created by a combination of streamer tomography and pre-stack depth migration velocities with seismic data including: a 2008 R/V Langseth dataset from the St. Elias Erosion and Tectonics Project (STEEP); and a 2004 high-resolution R/V Ewing dataset. Velocity-porosity-permeability relationships developed using IODP Expedition 341 drilling data inform interpretation and physical properties analyses of the shallow sediments. Initial results from a 35 km profile extending SE seaward of the Bering glacier and subparallel to the Bering trough

  11. Documenting mudstone heterogeneity by use of principal component analysis of X-ray diffraction and portable X-ray fluorescence data: A case study in the Triassic Shublik Formation, Alaska North Slope

    Science.gov (United States)

    Boehlke, Adam; Whidden, Katherine J.; Benzel, William M.

    2017-01-01

    Determining the chemical and mineralogical variability within fine-grained mudrocks poses analytical challenges but is potentially useful for documenting subtle stratigraphic differences in physicochemical environments that may influence petroleum reservoir properties and behavior. In this study, we investigate the utility of combining principal component analysis (PCA) of X-ray diffraction (XRD) data and portable X-ray fluorescence (pXRF) data to identify simplifying relationships within a large number of samples and subsequently evaluate a subset that encompasses the full spectrum or range of mineral and chemical variability within a vertical section. Samples were collected and analyzed from a vertical core of the Shublik Formation, a heterogeneous, phosphate-rich, calcareous mudstone-to-marl unit deposited in the Arctic Alaska Basin (AAB) during the Middle and Late Triassic. The Shublik is a major petroleum source rock in the Alaskan North Slope, and is considered a prime target for continuous self-sourced resource plays.

  12. Energy intensive industry for Alaska. Volume I: Alaskan cost factors; market factors; survey of energy-intensive industries

    Energy Technology Data Exchange (ETDEWEB)

    Swift, W.H.; Clement, M.; Baker, E.G.; Elliot, D.C.; Jacobsen, J.J.; Powers, T.B.; Rohrmann, C.A.; Schiefelbein, G.L.

    1978-09-01

    The Alaskan and product market factors influencing industry locations in the state are discussed and a survey of the most energy intensive industries was made. Factors external to Alaska that would influence development and the cost of energy and labor in Alaska are analyzed. Industries that are likely to be drawn to Alaska because of its energy resources are analyzed in terms of: the cost of using Alaska energy resources in Alaska as opposed to the Lower 48; skill-adjusted wage and salary differentials between relevant Alaskan areas and the Lower 48; and basic plant and equipment and other operating cost differentials between relevant Alaskan areas and the Lower 48. Screening and evaluation of the aluminum metal industry, cement industry, chlor-alkali industry, lime industry, production of methanol from coal, petroleum refining, and production of petrochemicals and agrichemicals from North Slope natural gas for development are made.

  13. Impact of Expanded North Slope of Alaska Crude Oil Production on Crude Oil Flows in the Contiguous United States

    Energy Technology Data Exchange (ETDEWEB)

    DeRosa, Sean E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flanagan, Tatiana Paz [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    The National Transportation Fuels Model was used to simulate a hypothetical increase in North Slope of Alaska crude oil production. The results show that the magnitude of production utilized depends in part on the ability of crude oil and refined products infrastructure in the contiguous United States to absorb and adjust to the additional supply. Decisions about expanding North Slope production can use the National Transportation Fuels Model take into account the effects on crude oil flows in the contiguous United States.

  14. Participatory Selection of Tree Species for Agroforestry on Sloping Land in North Korea

    Directory of Open Access Journals (Sweden)

    Jun He

    2015-11-01

    Full Text Available The action research project reported in this article used a participatory approach to select trees for sloping-land agroforestry as a key strategy for forest ecosystem restoration and local livelihood development. It was the first such project in the Democratic People’s Republic of Korea (North Korea to use a participatory approach, empowering local user groups to develop their preferences for agroforestry species. Local knowledge of the multiple functions of agroforestry species ensured that the tree selection criteria included the value of timber, fruit, fodder, oil, medicines, fuelwood, and erosion control. Involving 67 farmers from 3 counties, this participatory selection process resulted in Prunus armeniaca, Castanea crenata, and Ziziphus jujuba being selected as the top 3 species for the development of sloping-land agroforestry in North Hwanghae Province. These trees embody what the region’s farmers value most: erosion control, production of fruit, and economic value. The participatory approach in agroforestry could help to meet both local needs for food security and the national objective of environmental conservation and has great potential for wide adaptation in North Korea and beyond.

  15. Slope failures and timing of turbidity flows north of Puerto Rico

    Science.gov (United States)

    ten Brink, Uri S.; Chaytor, Jason D.

    2014-01-01

    The submerged carbonate platform north of Puerto Rico terminates in a high (3,000–4,000 m) and in places steep (>45°) slope characterized by numerous landslide scarps including two 30–50 km-wide amphitheater-shaped features. The origin of the steep platform edge and the amphitheaters has been attributed to: (1) catastrophic failure, or (2) localized failures and progressive erosion. Determining which of the two mechanisms has shaped the platform edge is critically important in understanding landslide-generated tsunami hazards in the region. Multibeam bathymetry, seismic reflection profiles, and a suite sediment cores from the Puerto Rico Trench and the slope between the trench and the platform edge were used to test these two hypotheses. Deposits within trench axis and at the base of the slope are predominantly composed of sandy carbonate turbidites and pelagic sediment with inter-fingering of chaotic debris units. Regionally-correlated turbidites within the upper 10 m of the trench sediments were dated between ∼25 and 22 kyrs and ∼18–19 kyrs for the penultimate and most recent events, respectively. Deposits on the slope are laterally discontinuous and vary from thin layers of fragmented carbonate platform material to thick pelagic layers. Large debris blocks or lobes are absent within the near-surface deposits at the trench axis and the base of slope basins. Progressive small-scale scalloping and self-erosion of the carbonate platform and underlying stratigraphy appears to be the most likely mechanism for recent development of the amphitheaters. These smaller scale failures may lead to the generation of tsunamis with local, rather than regional, impact.

  16. Co-movements of Alaska North Slope and UK Brent crude oil prices

    International Nuclear Information System (INIS)

    Ewing, B.T.; Harter, C.L.

    2000-01-01

    In order to study the inter-relationships of international crude oil markets, empirical analyses are used to investigate univariate and multivariate relationships between Alaska North Slope and UK Brent oil prices. Using monthly data from the period 1974-1996, the results show that both price series follow a random walk and that these oil markets share a long-run common trend. The empirical results suggest that the two markets are 'unified'. That is, they are competitive, and there is price convergence in the markets. (author)

  17. The Upper 1000-m Slope Currents North of the South Shetland Islands and Elephant Island Based on Ship Cruise Observations

    Science.gov (United States)

    Du, Guangqian; Zhang, Zhaoru; Zhou, Meng; Zhu, Yiwu; Zhong, Yisen

    2018-04-01

    While the Antarctic Slope Current (ASC) has been intensively studied for the East Antarctica slope area and the Weddell Sea, its fate in the western Antarctic Peninsula (WAP) region remains much less known. Data from two cruises conducted near the South Shetland Islands (SSIs) and the Elephant Island (EI), one in austral summer of 2004 and one in austral winter of 2006, were analyzed to provide a broad picture of the circulation pattern over the continental slope of the surveyed area, and an insight into the dynamical balance of the circulation. The results indicate that southwestward currents are present over the upper slope in the study area, indicating the ASC in the WAP region. Near the Shackleton Gap (SG) north of the EI, the southwestward slope currents near the shelf break are characterized by a water mass colder and fresher than the ambient water, which produces cross-slope density gradients and then vertical shear of the along-slope (or along-isobath) velocity. The vertical shear is associated with a reversal of the along-slope current from northeastward at surface to southwestward in deeper layers, or a depth-intensification of the southwestward slope currents. The water mass with temperature and salinity characteristics similar to the observed cold and fresh water is also revealed on the southern slope of the Scotia Sea, suggesting that this cold and fresh water is originated from the Scotia Sea slope and flows southwestward through the SG. Over the shelf north of the SSIs, the cold and fresh water mass is also observed and originates mainly from the Bransfield Strait. In this area, vertical structure of the southwestward slope currents is associated with the onshore intrusion of the upper Circumpolar Deep Water that creates cross-slope density gradients.

  18. Submarine landslides on the north continental slope of the South China Sea

    Science.gov (United States)

    Wang, Weiwei; Wang, Dawei; Wu, Shiguo; Völker, David; Zeng, Hongliu; Cai, Guanqiang; Li, Qingping

    2018-02-01

    Recent and paleo-submarine landslides are widely distributed within strata in deep-water areas along continental slopes, uplifts, and carbonate platforms on the north continental margin of the South China Sea (SCS). In this paper, high-resolution 3D seismic data and multibeam data based on seismic sedimentology and geomorphology are employed to assist in identifying submarine landslides. In addition, deposition models are proposed that are based on specific geological structures and features, and which illustrate the local stress field over entire submarine landslides in deep-water areas of the SCS. The SCS is one of the largest fluvial sediment sinks in enclosed or semi-enclosed marginal seas worldwide. It therefore provides a set of preconditions for the formation of submarine landslides, including rapid sediment accumulation, formation of gas hydrates, and fluid overpressure. A new concept involving temporal and spatial analyses is tested to construct a relationship between submarine landslides and different time scale trigger mechanisms, and three mechanisms are discussed in the context of spatial scale and temporal frequency: evolution of slope gradient and overpressure, global environmental changes, and tectonic events. Submarine landslides that are triggered by tectonic events are the largest but occur less frequently, while submarine landslides triggered by the combination of slope gradient and over-pressure evolution are the smallest but most frequently occurring events. In summary, analysis shows that the formation of submarine landslides is a complex process involving the operation of different factors on various time scales.

  19. Collaborative community hazard exposure mapping: Distant Early Warning radar sites in Alaska's North Slope

    Science.gov (United States)

    Brady, M.

    2015-12-01

    A method to produce hazard exposure maps that are developed in collaboration with local coastal communities is the focus of this research. Typically efforts to map community exposure to climate threats over large areas have limited consideration of local perspectives about associated risks, constraining their utility for local management. This problem is especially acute in remote locations such as the Arctic where there are unique vulnerabilities to coastal threats that can be fully understood only through inclusion of community stakeholders. Through collaboration with community members, this study identifies important coastal assets and places and surveys local perspectives of exposure to climate threats along Alaska's vast North Slope coastline spanning multiple municipalities. To model physical exposure, the study adapts the U.S. Geological Survey's (USGS) coastal vulnerability index (CVI) to the Arctic context by incorporating the effects of open water distance determined by sea ice extent, and assigning CVI values to coastal assets and places according to direction and proximity. The study found that in addition to concerns about exposed municipal and industrial assets, North Slope communities viewed exposure of traditional activity sites as presenting a particular risk for communities. Highly exposed legacy Cold War Distant Early Warning Line sites are of particular concern with impacts ranging from financial risk to contamination of sensitive coastal marine environments. This research demonstrates a method to collaboratively map community exposure to coastal climate threats to better understand local risks and produce locally usable exposure maps.

  20. Seasonal electrical resistivity surveys of a coastal bluff, Barter Island, North Slope Alaska

    Science.gov (United States)

    Swarzenski, Peter W.; Johnson, Cordell; Lorenson, Thomas; Conaway, Christopher H.; Gibbs, Ann E.; Erikson, Li; Richmond, Bruce M.; Waldrop, Mark P.

    2016-01-01

    Select coastal regions of the North Slope of Alaska are experiencing high erosion rates that can be attributed in part to recent warming trends and associated increased storm intensity and frequency. The upper sediment column of the coastal North Slope of Alaska can be described as continuous permafrost underlying a thin (typically less than 1–2 m) active layer that responds variably to seasonal thaw cycles. Assessing the temporal and spatial variability of the active layer and underlying permafrost is essential to better constrain how heightened erosion may impact material fluxes to the atmosphere and the coastal ocean, and how enhanced thaw cycles may impact the stability of the coastal bluffs. In this study, multi-channel electrical resistivity tomography (ERT) was used to image shallow subsurface features of a coastal bluff west of Kaktovik, on Barter Island, northeast Alaska. A comparison of a suite of paired resistivity surveys conducted in early and late summer 2014 provided detailed information on how the active layer and permafrost are impacted during the short Arctic summer. Such results are useful in the development of coastal resilience models that tie together fluvial, terrestrial, climatic, geologic, and oceanographic forcings on shoreline stability.

  1. Alaska North Slope crude oil price and the behavior of diesel prices in California

    International Nuclear Information System (INIS)

    Adrangi, B.; Chatrath, A.; Raffiee, K.; Ripple, R.

    2001-01-01

    In this paper we analyze the price dynamics of Alaska North Slope crude oil and L.A. diesel fuel prices. We employ VAR methodology and bivariate GARCH model to show that there is a strong evidence of a uni-directional causal relationship between the two prices. The L.A. diesel market is found to bear the majority of the burden of convergence when there is a price spread. This finding may be seen as being consistent with the general consensus that price discovery emanates from the larger, more liquid market where trading volume is concentrated. The contestability of the West Coast crude oil market tends to cause it to react relatively competitively, while the lack of contestability for the West Coast diesel market tends to limit its competitiveness, causing price adjustment to be slow but to follow the price signals of crude oil. Our findings also suggest that the derived demand theory of input pricing may not hold in this case. The Alaska North Slope crude oil price is the driving force in changes of L.A. diesel price

  2. Local Community Verification of Coastal Erosion Risks in the Arctic: Insights from Alaska's North Slope

    Science.gov (United States)

    Brady, M.

    2016-12-01

    During his historic trip to Alaska in 2015, U.S. President Barack Obama announced a collaborative effort to update maps of the Arctic region in anticipation of increased maritime access and resource development and to support climate resilience. Included in this effort is development of an Arctic-wide satellite-based digital elevation model (DEM) to provide a baseline to monitor landscape change such as coastal erosion. Focusing in Alaska's North Slope, an objective of this study is to transform emerging Arctic environment spatial data products including the new DEM into information that can support local level planning and decision-making in the face of extreme coastal erosion and related environmental threats. In pursuit of this, in 2016, 4 workshops were held in three North Slope villages highly exposed to coastal erosion. The first workshop with approximately 10 managers in Barrow solicited feedback on an erosion risk database developed in a previous research stage and installed onto the North Slope's planning Web portal. The database includes a physical risk indicator based on factors such as historical erosion and effects of sea ice loss summarized at asset locations. After a demonstration of the database, participants discussed usability aspects such as data reliability. The focus of the mapping workshops in Barrow and two smaller villages Wainwright and Kaktovik was to verify and expand the risk database by interactively mapping erosion observations and community asset impacts. Using coded stickers and paper maps of the shoreline showing USGS erosion rates, a total of 50 participants provided feedback on erosion data accuracy. Approximately 25 of the total 50 participants were elders and hunters who also provided in-depth community risk information. The workshop with managers confirmed physical risk factors used in the risk database, and revealed that the information may be relied upon to support some development decisions and better engage developers about

  3. Biogenic and fossil contributions to organic aerosol at two sites on the North Slope of Alaska

    Science.gov (United States)

    Moffett, Claire; Barrett, Tate; Gunsch, Matthew; Pratt, Kerri; Sheesley, Rebecca

    2017-04-01

    Aerosols both directly and indirectly affect the Earth's albedo by scattering or absorbing solar radiation and acting as cloud and ice condensation nuclei. In order to better understand the variability of aerosol sources in the Alaskan Arctic, this study utilizes radiocarbon analysis for the apportionment of total organic carbon to fossil and contemporary carbon sources. Fossil sources include fossil fuel combustion and secondary organic aerosol (SOA) from fossil precursors while contemporary sources include biomass combustion, primary biogenic emissions, and SOA produced from biogenic and biomass combustion-derived precursors. Total suspended particulate (TSP) samples were collected in August/September 2012, 2015, and 2016 at two Department of Energy Atmospheric Radiation Measurement climate research facilities. Barrow, AK, is located on the northern most point of the United States; the site is 7.4 km north of the village of Barrow (population 4,581). Research shows the site receives minimal aerosol contribution from the village with dominant contributions from long range transport. Oliktok Point, AK, is 300 km south east of Barrow in a region of intense petroleum development. It receives contributions from the petroleum industry surrounding it as well as from long range transport. The proximity of the two sites allows for a finer spatial analysis of Arctic carbonaceous aerosol source contributions. Samples were analyzed for organic carbon (OC), elemental carbon (EC), and radiocarbon (14C) abundance. Preliminary results for 2015 show Barrow had OC concentrations from 0.05 to 0.16 μg/m3, while Oliktok had concentrations of OC from 0.11 to 0.27 μg/m3. EC concentrations ranged from 0.002 to 0.013 μg/m3 in Barrow, 0.002 to 0.088 μg/m3 in Oliktok. In Barrow, 14C abundance shows the contribution of fossil sources remained in the range of 21% to 28%. At Oliktok, analysis reveals an increase from 30% contribution from fossil sources in August to a 70% contribution at

  4. Slope aspect influences arbuscular mycorrhizal fungus communities in arid ecosystems of the Daqingshan Mountains, Inner Mongolia, North China.

    Science.gov (United States)

    Liu, Min; Zheng, Rong; Bai, Shulan; Bai, Yv E; Wang, Jugang

    2017-04-01

    Arbuscular mycorrhizal (AM) symbiosis plays an important role in ecosystem functioning, particularly in fragile environments. Little is known, however, about how AM fungus community composition responds to slope aspect. Our objective was to compare the AM fungus communities between sunny and shady slopes and to detect factors that influenced the distributions of AM fungi in arid ecosystems of the Daqingshan Mountains, Inner Mongolia, North China. AM fungus communities were evaluated based on small subunit ribosomal RNA genes (SSUs) using Illumina MiSeq sequencing. AM fungus community composition differed significantly between slope aspects, and sunny slopes had significantly higher AM fungus diversity and richness as well as spore density, total root colonization, arbuscule abundance, vesicle abundance, and hyphal colonization than shady slopes. Structural equation modeling (SEM) illustrated that the effects of slope aspect on AM fungus richness likely were mediated by available phosphorus, soil organic carbon, plant cover, and plant diversity. Available phosphorus was the principal factor that influenced AM fungus species richness, and soil organic carbon was the principal factor influencing spore density and total root colonization, suggesting that these factors especially might be responsible for differences between the AM fungus communities of different slope aspects. These findings elucidate the influence of slope aspect on AM fungus communities and may inform use of AM fungi in protection and restoration of vegetation with different slope aspects in arid ecosystems.

  5. Biodegradation of Alaska North Slope crude oil enhanced by commercial bioremediation agents

    International Nuclear Information System (INIS)

    Aldrett, S.; Bonner, J.S.; Mills, M.A.; McDonald, T.J.; Autenrieth, R.L.

    1996-01-01

    The biodegradation of crude oil was studied. Tests were conducted in which natural unpolluted seawater was collected and then contaminated with Alaska North Slope crude oil. The oil was weathered by heating it to 521 degrees F to remove the light-end hydrocarbons. A total of 13 different bioremediation agents were tested, each one separately. Three samples per treatment were destructively analysed for petroleum chemistry. The thirteen treatments were analyzed for oil and grease. It was found that microbial degradation of petroleum hydrocarbons was enhanced by the addition of bioremediation agents, but it was not possible to identify the intermediate products responsible for the increase of resolved petroleum hydrocarbons through time. It was suggested that caution be used when interpreting results since the protocols used to test the products were prone to uncontrollable variations. 11 refs., 5 tabs., 6 figs

  6. Physical and Chemical Implications of Mid-Winter Pumping of Trunda Lakes - North Slope, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Hinzman, Larry D. (University of Alaska Fairbanks, Water and Environmental Research Center); Lilly, Michael R. (Geo-Watersheds Scientific); Kane, Douglas L. (University of Alaska Fairbanks, Water and Environmental Research Center); Miller, D. Dan (University of Alaska Fairbanks, Water and Environmental Research Center); Galloway, Braden K. (University of Alaska Fairbanks, Water and Environmental Research Center); Hilton, Kristie M. (Geo-Watersheds Scientific); White, Daniel M. (University of Alaska Fairbanks, Water and Environmental Research Center)

    2005-09-30

    Tundra lakes on the North Slope, Alaska, are an important resource for energy development and petroleum field operations. A majority of exploration activities, pipeline maintenance, and restoration activities take place on winter ice roads that depend on water availability at key times of the winter operating season. These same lakes provide important fisheries and ecosystem functions. In particular, overwintering habitat for fish is one important management concern. This study focused on the evaluation of winter water use in the current field operating areas to provide a better understanding of the current water use practices. It found that under the current water use practices, there were no measurable negative effects of winter pumping on the lakes studied and current water use management practices were appropriately conservative. The study did find many areas where improvements in the understanding of tundra lake hydrology and water usage would benefit industry, management agencies, and the protection of fisheries and ecosystems.

  7. Alaska North Slope National Energy Strategy initiative: Analysis of five undeveloped fields

    International Nuclear Information System (INIS)

    Thomas, C.P.; Allaire, R.B.; Doughty, T.C.; Faulder, D.D.; Irving, J.S.; Jamison, H.C.; White, G.J.

    1993-05-01

    The US Department of Energy was directed in the National Energy Strategy to establish a federal interagency task force to identify specific technical and regulatory barriers to the development of five undeveloped North Slope Alaska fields and make recommendations for their resolution. The five fields are West Sak, Point Thomson, Gwydyr Bay, Seal Island/Northstar, and Sandpiper Island. Analysis of environmental, regulatory, technical, and economic information, and data relating to the development potential of the five fields leads to the following conclusions: Development of the five fields would result in an estimated total of 1,055 million barrels of oil and 4.4 trillion cubic feet of natural gas and total investment of $9.4 billion in 1992 dollars. It appears that all five of the fields will remain economically marginal developments unless there is significant improvement in world oil prices. Costs of regulatory compliance and mitigation, and costs to reduce or maintain environmental impacts at acceptable levels influence project investments and operating costs and must be considered in the development decision making process. The development of three of the fields (West Sak, Point Thomson, and Gwydyr Bay) that are marginally feasible would have an impact on North Slope production over the period from about 2000 to 2014 but cannot replace the decline in Prudhoe Bay Unit production or maintain the operation of the Trans-Alaska Pipeline System (TAPS) beyond about 2014 with the assumption that the TAPS will shut down when production declines to the range of 400 to 200 thousand barrels of oil/day. Recoverable reserves left in the ground in the currently producing fields and soon to be developed fields, Niakuk and Point McIntyre, would range from 1 billion to 500 million barrels of oil corresponding to the time period of 2008 to 2014 based on the TAPS shutdown assumption

  8. Alaska North Slope National Energy Strategy initiative: Analysis of five undeveloped fields

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, C.P.; Allaire, R.B.; Doughty, T.C.; Faulder, D.D.; Irving, J.S.; Jamison, H.C.; White, G.J.

    1993-05-01

    The US Department of Energy was directed in the National Energy Strategy to establish a federal interagency task force to identify specific technical and regulatory barriers to the development of five undeveloped North Slope Alaska fields and make recommendations for their resolution. The five fields are West Sak, Point Thomson, Gwydyr Bay, Seal Island/Northstar, and Sandpiper Island. Analysis of environmental, regulatory, technical, and economic information, and data relating to the development potential of the five fields leads to the following conclusions: Development of the five fields would result in an estimated total of 1,055 million barrels of oil and 4.4 trillion cubic feet of natural gas and total investment of $9.4 billion in 1992 dollars. It appears that all five of the fields will remain economically marginal developments unless there is significant improvement in world oil prices. Costs of regulatory compliance and mitigation, and costs to reduce or maintain environmental impacts at acceptable levels influence project investments and operating costs and must be considered in the development decision making process. The development of three of the fields (West Sak, Point Thomson, and Gwydyr Bay) that are marginally feasible would have an impact on North Slope production over the period from about 2000 to 2014 but cannot replace the decline in Prudhoe Bay Unit production or maintain the operation of the Trans-Alaska Pipeline System (TAPS) beyond about 2014 with the assumption that the TAPS will shut down when production declines to the range of 400 to 200 thousand barrels of oil/day. Recoverable reserves left in the ground in the currently producing fields and soon to be developed fields, Niakuk and Point McIntyre, would range from 1 billion to 500 million barrels of oil corresponding to the time period of 2008 to 2014 based on the TAPS shutdown assumption.

  9. Engaging Stakeholders through Participatory Mapping and Spatial Analysis in a Scenarios Process for Alaska's North Slope

    Science.gov (United States)

    Fradkin, B.; Vargas, J. C.; Lee, O. A.; Emperador, S.

    2016-12-01

    A scenarios process was conducted for Alaska's North Slope to consider the wide range of drivers of change and uncertainties that could contribute to shifts in research and monitoring needs over the next 25 years. The project team, consisting of specialists in participatory scenarios and academic researchers, developed an interactive approach that helped facilitate the exploration of a range of plausible changes in the region. Over two years, the team designed and executed a series of workshops to capitalize on the collective expertise of researchers, resource managers, industry representatives, and traditional and local knowledge holders on the North Slope. The goal of this process was to evaluate three energy and resource development scenarios, which incorporated biophysical and socioeconomic drivers, to assess the implications of development on high-priority biophysical resources and the subsistence lifestyle and well-being of its Inupiat residents. Due to the diversity of the stakeholders engaged in the process, the workshop materials and activities had to be carefully designed and executed, in order to provide an adequate platform for discussion of each scenario component, as well as generating products that would provide management-relevant information to the NSSI and its member entities. Each workshop implemented a participatory mapping component, which relied on the best available geospatial datasets to generate informational maps that enabled participants to effectively consider a wide range of variables and outcomes for each of the selected scenarios. In addition, the map sketches produced in each workshop were digitized and incorporated into a spatial analysis that evaluated the level of agreement between stakeholder groups, as well as evaluating the geographic overlap of development features and anticipated implications with terrestrial and marine habitats, subsistence hunting zones, and sensitive landscape elements such as permafrost. This presentation

  10. Impact of Expanded North Slope of Alaska Crude Oil Production on Oil Flows in the Contiguous United States (Summary)

    Energy Technology Data Exchange (ETDEWEB)

    DeRosa, Sean e. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flanagan, Tatiana Paz [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Crude oil produced on the North Slope of Alaska (NSA) is primarily transported on the Trans-Alaska Pipeline System (TAPS) to in-state refineries and the Valdez Marine Terminal in southern Alaska. From the Terminal, crude oil is loaded onto tankers and is transported to export markets or to three major locations along the U.S. West Coast: Anacortes-Ferndale area (Washington), San Francisco Bay area, and Los Angeles area. North Slope of Alaska production has decreased about 75% since the 1980s, which has reduced utilization of TAPS.

  11. The Wahluke (North) Slope of the Hanford Site: History and present challenges

    International Nuclear Information System (INIS)

    Gerber, M.S.

    1996-01-01

    The Hanford Site was founded in early 1943 for the top secret government mission of producing plutonium for the world's first atomic weapons. A great deal of land was needed, both to separate various Site facilities from each other, and to provide buffer zones for safety and security purposes. In total, 640 square miles were occupied by the original Hanford Site and its buffer zones. Much of this land had been earmarked for inclusion in the Columbia Basin Irrigation Project (CBP). After World War II ended, a series of national decisions led to a long-term mission for the Hanford Site, and area residents learned that the Site lands they had hoped to farm would be withheld from agricultural production for the foreseeable future. A long set of negotiations commenced between the federal management agency responsible for Hanford (the Atomic Energy Commission -- AEC), and the Bureau of Reclamation (BOR), Department of the Interior that managed the CBP. Some lands were turned back to agriculture, and other compromises made, in the Site's far northern buffer lands known as the Wahluke Slope, during the 1950s. In the mid-1960s, further negotiations were about to allow farming on lands just north of the Columbia River, opposite Hanford's reactors, when studies conducted by the BOR found drainage barriers to irrigation. As a result of these findings, two wildlife refuges were created on that land in 1971. Today, after the Hanford Site plutonium production mission has ended and as Site cleanup goes forward, the possibility of total release of Wahluke Slope lands from the control of the Department of Energy (DOE -- a successor agency to the AEC) is under discussion. Such discussion encompasses not just objective and clearly visible criteria, but it resurrects historical debates about the roles of farming and government presence in the Columbia Basin

  12. North Slope of Alaska Snow Intensive Operational Period Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Verlinde, Johannes [Pennsylvania State Univ., University Park, PA (United States); Bartholomew, Mary Jane [Brookhaven National Lab. (BNL), Upton, NY (United States); Cherry, Jessica [Univ. of Alaska, Fairbanks, AK (United States); Ritsche, Michael [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-05-15

    The campaign was motivated by the need to improve the quantification of measurements of ice-phase precipitation in the Arctic and was by the acquisition and deployment of the new X- and Ka/W-band radars. These radars opened up an opportunity for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility to obtain spatial estimates of snowfall rates using the polarimetric X-band measurements and dual-frequency measurements (using different combinations of the three wavelengths). However, calculations of X- and Ka-band radar back-scattering of ice crystal aggregates with their complex structure suggest that the commonly used T-matrix approach (Matrosov et al. 2007) for modeling the radar back-scattering underestimates the reflectivity by several decibels, with errors increasing with increasing radar frequency (Botta et al. 2010, 2011). Moreover, the X-band polarimetric measurements and the Ka/W-band measurements are sensitive to the assumed shape of the snow (Botta et al. 2011). One of the five ARM two-dimensional video disdrometers (manufactured by Joanneum Research) were deployed in Barrow at the ARM North Slope of Alaska (NSA) site from 1 October, 2011 to 31 May, 2012 in an attempt to use the instrument in a novel way. The instrument was originally designed to measure the drop size distribution of rain but it seemed worthwhile to explore its capability to quantify ice precipitation particle size and shape distributions in the cold north for scattering calculations and precipitation estimations. Furthermore, this deployment gave us an opportunity to see how reliable it could be in arctic conditions.

  13. Tundra plant above-ground biomass and shrub dominance mapped across the North Slope of Alaska

    Science.gov (United States)

    Berner, Logan T.; Jantz, Patrick; Tape, Ken D.; Goetz, Scott J.

    2018-03-01

    Arctic tundra is becoming greener and shrubbier due to recent warming. This is impacting climate feedbacks and wildlife, yet the spatial distribution of plant biomass in tundra ecosystems is uncertain. In this study, we mapped plant and shrub above-ground biomass (AGB; kg m-2) and shrub dominance (%; shrub AGB/plant AGB) across the North Slope of Alaska by linking biomass harvests at 28 field sites with 30 m resolution Landsat satellite imagery. We first developed regression models (p accounting for ~43% of regional plant AGB. The new maps capture landscape variation in plant AGB visible in high resolution satellite and aerial imagery, notably shrubby riparian corridors. Modeled shrub AGB was strongly correlated with field measurements of shrub canopy height at 25 sites (rs  = 0.88) and with a regional map of shrub cover (rs  = 0.76). Modeled plant AGB and shrub dominance were higher in shrub tundra than graminoid tundra and increased between areas with the coldest and warmest summer air temperatures, underscoring the fact that future warming has the potential to greatly increase plant AGB and shrub dominance in this region. These new biomass maps provide a unique source of ecological information for a region undergoing rapid environmental change.

  14. Carbon and geochemical properties of cryosols on the North Slope of Alaska

    Science.gov (United States)

    Mu, Cuicui; Zhang, Tingjun; Schuster, Paul F.; Schaefer, Kevin; Wickland, Kimberly P.; Repert, Deborah A.; Liu, Lin; Schaefer, Tim; Cheng, Guodong

    2014-01-01

    Cryosols contain roughly 1700 Gt of Soil organic carbon (SOC) roughly double the carbon content of the atmosphere. As global temperature rises and permafrost thaws, this carbon reservoir becomes vulnerable to microbial decomposition, resulting in greenhouse gas emissions that will amplify anthropogenic warming. Improving our understanding of carbon dynamics in thawing permafrost requires more data on carbon and nitrogen content, soil physical and chemical properties and substrate quality in cryosols. We analyzed five permafrost cores obtained from the North Slope of Alaska during the summer of 2009. The relationship between SOC and soil bulk density can be adequately represented by a logarithmic function. Gas fluxes at − 5 °C and 5 °C were measured to calculate the temperature response quotient (Q10). Q10 and the respiration per unit soil C were higher in permafrost-affected soils than that in the active layer, suggesting that decomposition and heterotrophic respiration in cryosols may contribute more to global warming.

  15. The freshwater biodegradation potential of nine Alaskan oils

    International Nuclear Information System (INIS)

    Blenkinsopp, S.; Segy, G.

    1997-01-01

    Nine Alaskan representative crude oils and oil products with freshwater spill potential were collected, aged, and incubated in the presence of the standard freshwater inoculum for 28 days at 10 degrees C. Detailed analytical chemistry was performed on all samples to quantify compositional changes. All of the samples tested exhibited measurable hydrocarbon loss as a result of incubation with the freshwater inoculum. Total saturate and total n-alkane biodegradation were greatly enhanced when nutrients were present. The oil products Jet B Fuel and Diesel No. 2 appear to be more biodegradable than the Alaska North Slope and Cook Inlet crude oils tested, while the Bunker C/Diesel mixture appears to be less biodegradable than these crude oils. These results suggest that the screening procedures described here can provide useful information when applying bioremediation technology to the cleanup of selected oiled freshwater environments. 10 refs., 5 tabs., 13 figs

  16. Uniform shrub growth response to June temperature across the North Slope of Alaska

    Science.gov (United States)

    Ackerman, Daniel E.; Griffin, Daniel; Hobbie, Sarah E.; Popham, Kelly; Jones, Erin; Finlay, Jacques C.

    2018-04-01

    The expansion of woody shrubs in arctic tundra alters many aspects of high-latitude ecosystems, including carbon cycling and wildlife habitat. Dendroecology, the study of annual growth increments in woody plants, has shown promise in revealing how climate and environmental conditions interact with shrub growth to affect these key ecosystem properties. However, a predictive understanding of how shrub growth response to climate varies across the heterogeneous landscape remains elusive. Here we use individual-based mixed effects modeling to analyze 19 624 annual growth ring measurements in the stems of Salix pulchra (Cham.), a rapidly expanding deciduous shrub. Stem samples were collected at six sites throughout the North Slope of Alaska. Sites spanned four landscapes that varied in time since glaciation and hence in soil properties, such as nutrient availability, that we expected would modulate shrub growth response to climate. Ring growth was remarkably coherent among sites and responded positively to mean June temperature. The strength of this climate response varied slightly among glacial landscapes, but in contrast to expectations, this variability was not systematically correlated with landscape age. Additionally, shrubs at all sites exhibited diminishing marginal growth gains in response to increasing temperatures, indicative of alternative growth limiting mechanisms in particularly warm years, such as temperature-induced moisture limitation. Our results reveal a regionally-coherent and robust shrub growth response to early season growing temperature, with local soil properties contributing only a minor influence on shrub growth. Our conclusions strengthen predictions of changes to wildlife habitat and improve the representation of tundra vegetation dynamics in earth systems models in response to future arctic warming.

  17. A comprehensive climatology of Arctic aerosol properties on the North Slope of Alaska

    Science.gov (United States)

    Creamean, Jessie; de Boer, Gijs; Shupe, Matthew; McComiskey, Allison

    2016-04-01

    Evaluating aerosol properties has implications for the formation of Arctic clouds, resulting in impacts on cloud lifetime, precipitation processes, and radiative forcing. There are many remaining uncertainties and large discrepancies regarding modeled and observed Arctic aerosol properties, illustrating the need for more detailed observations to improve simulations of Arctic aerosol and more generally, projections of the components of the aerosol-driven processes that impact sea ice loss/gain. In particular, the sources and climatic effects of Arctic aerosol particles are severely understudied. Here, we present a comprehensive, long-term record of aerosol observations from the North Slope of Alaska baseline site at Barrow. These measurements include sub- and supermicron (up to 10 μm) total mass and number concentrations, sub- and supermicron soluble inorganic and organic ion concentrations, submicron metal concentrations, submicron particle size distributions, and sub- and supermicron absorption and scattering properties. Aerosol extinction and number concentration measurements extend back to 1976, while the remaining measurements were implemented since. Corroboration between the chemical, physical, and optical property measurements is evident during periods of overlapping observations, demonstrating the reliability of the measurements. During the Arctic Haze in the winter/spring, high concentrations of long-range transported submicron sea salt, mineral dust, industrial metals, pollution (non-sea salt sulfate, nitrate, ammonium), and biomass burning species are observed concurrent with higher concentrations of particles with sizes that span the submicron range, enhanced absorption and scattering coefficients, and largest Ångström exponents. The summer is characterized by high concentrations of small biogenic aerosols (sea salt representing the dominant aerosol type supporting the highest single scattering albedos. This complete set of aerosol properties can be

  18. ARM-ACME V: ARM Airborne Carbon Measurements V on the North Slope of Alaska Science and Implementation Plan

    Energy Technology Data Exchange (ETDEWEB)

    Biraud, S [Lawrence Berkeley National Laboratory

    2015-05-01

    Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO₂ and/or CH₄) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols, and cloud properties at the North Slope of Alaska are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections.

  19. Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Overview of scientific and technical program

    Science.gov (United States)

    Hunter, R.B.; Collett, T.S.; Boswell, R.; Anderson, B.J.; Digert, S.A.; Pospisil, G.; Baker, R.; Weeks, M.

    2011-01-01

    The Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled within the Alaska North Slope (ANS) Milne Point Unit (MPU) from February 3 to 19, 2007. The well was conducted as part of a Cooperative Research Agreement (CRA) project co-sponsored since 2001 by BP Exploration (Alaska), Inc. (BPXA) and the U.S. Department of Energy (DOE) in collaboration with the U.S. Geological Survey (USGS) to help determine whether ANS gas hydrate can become a technically and commercially viable gas resource. Early in the effort, regional reservoir characterization and reservoir simulation modeling studies indicated that up to 0.34 trillion cubic meters (tcm; 12 trillion cubic feet, tcf) gas may be technically recoverable from 0.92 tcm (33 tcf) gas-in-place within the Eileen gas hydrate accumulation near industry infrastructure within ANS MPU, Prudhoe Bay Unit (PBU), and Kuparuk River Unit (KRU) areas. To further constrain these estimates and to enable the selection of a test site for further data acquisition, the USGS reprocessed and interpreted MPU 3D seismic data provided by BPXA to delineate 14 prospects containing significant highly-saturated gas hydrate-bearing sand reservoirs. The "Mount Elbert" site was selected to drill a stratigraphic test well to acquire a full suite of wireline log, core, and formation pressure test data. Drilling results and data interpretation confirmed pre-drill predictions and thus increased confidence in both the prospect interpretation methods and in the wider ANS gas hydrate resource estimates. The interpreted data from the Mount Elbert well provide insight into and reduce uncertainty of key gas hydrate-bearing reservoir properties, enable further refinement and validation of the numerical simulation of the production potential of both MPU and broader ANS gas hydrate resources, and help determine viability of potential field sites for future extended term production testing. Drilling and data acquisition operations demonstrated that gas hydrate

  20. Chemical and Microbial Characterization of North Slope Viscous Oils to Assess Viscosity Reduction and Enhanced Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Shirish Patil; Abhijit Dandekar; Mary Beth Leigh

    2008-12-31

    A large proportion of Alaska North Slope (ANS) oil exists in the form of viscous deposits, which cannot be produced entirely using conventional methods. Microbially enhanced oil recovery (MEOR) is a promising approach for improving oil recovery for viscous deposits. MEOR can be achieved using either ex situ approaches such as flooding with microbial biosurfactants or injection of exogenous surfactant-producing microbes into the reservoir, or by in situ approaches such as biostimulation of indigenous surfactant-producing microbes in the oil. Experimental work was performed to analyze the potential application of MEOR to the ANS oil fields through both ex situ and in situ approaches. A microbial formulation containing a known biosurfactant-producing strain of Bacillus licheniformis was developed in order to simulate MEOR. Coreflooding experiments were performed to simulate MEOR and quantify the incremental oil recovery. Properties like viscosity, density, and chemical composition of oil were monitored to propose a mechanism for oil recovery. The microbial formulation significantly increased incremental oil recovery, and molecular biological analyses indicated that the strain survived during the shut-in period. The indigenous microflora of ANS heavy oils was investigated to characterize the microbial communities and test for surfactant producers that are potentially useful for biostimulation. Bacteria that reduce the surface tension of aqueous media were isolated from one of the five ANS oils (Milne Point) and from rock oiled by the Exxon Valdez oil spill (EVOS), and may prove valuable for ex situ MEOR strategies. The total bacterial community composition of the six different oils was evaluated using molecular genetic tools, which revealed that each oil tested possessed a unique fingerprint indicating a diverse bacterial community and varied assemblages. Collectively we have demonstrated that there is potential for in situ and ex situ MEOR of ANS oils. Future work

  1. POTENTIALLY UNSTABLE SLOPE ABOVE ORE PROCESSING PLANT IN THE "OČURA" DOLOMITE QUARRY (LEPOGLAVA, NORTH CROATIA

    Directory of Open Access Journals (Sweden)

    Karlo Braun

    1993-12-01

    Full Text Available The complex engineering investigation, in the nearest surroun-dig of the conditionally stable high slope, close to ore processing facilities in the dolomite quarry »Očura« near Lepoglava (North Croatia, was carried out. Studying the tectonic features of the rock mass, discontinuities referent to the slope stability, was found out. Rock fragment size was measured and data processed using statistical design. According to rock fragment mean values, velocity of the longitudinal seismic waves was predicted. This values was compared with velocities of the longitudinal seismic waves, determined using gcophisical refraction seismic method. Physical and mechanical properties of the dolomite rock mass, considering longitudinal and transversal seismic wave velocities, and »RMR«-classification was assesed. All the results indicate, that the slope above the ore processing facilities should be consider as conditionally stable, with real probability to get unstable under the vibrations caused by blasting, during the exploitation in the field, close behind the investigated slope (the paper is published in Croatian.

  2. Ship Track for Islands in the Stream 2002 - Exploration of Outer Shelf and Slope Habitats off the Coast of North Carolina - Office of Ocean Exploration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ship track of the R/V Seward Johnson during the 2002 "Islands in the Stream - Exploration of Outer Shelf and Slope Habitats off the Coast of North Carolina"...

  3. PAH data in tissues of subsistence harvested marine mammal - Determination of PAH baseline values in tissues from subsistence-harvested marine mammals on the North Slope

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Over the past 15 years, high quality marine mammal tissue and fluid samples collected by subsistence hunters in the North Slope region of Alaska have been archived...

  4. Environmental Sensitivity Index (ESI) Atlas: Alaska - 2, Northwest Arctic - 2002, North Slope - 2005, Western - 2003, maps and geographic systems data (NODC Accession 0049913)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) data for Northwest Arctic, North Slope, and Western Alaska. ESI data characterize estuarine...

  5. SOLVENT-BASED ENHANCED OIL RECOVERY PROCESSES TO DEVELOP WEST SAK ALASKA NORTH SLOPE HEAVY OIL RESOURCES

    Energy Technology Data Exchange (ETDEWEB)

    David O. Ogbe; Tao Zhu

    2004-01-01

    A one-year research program is conducted to evaluate the feasibility of applying solvent-based enhanced oil recovery processes to develop West Sak and Ugnu heavy oil resources found on the Alaska North Slope (ANS). The project objective is to conduct research to develop technology to produce and market the 300-3000 cp oil in the West Sak and Ugnu sands. During the first phase of the research, background information was collected, and experimental and numerical studies of vapor extraction process (VAPEX) in West Sak and Ugnu are conducted. The experimental study is designed to foster understanding of the processes governing vapor chamber formation and growth, and to optimize oil recovery. A specially designed core-holder and a computed tomography (CT) scanner was used to measure the in-situ distribution of phases. Numerical simulation study of VAPEX was initiated during the first year. The numerical work completed during this period includes setting up a numerical model and using the analog data to simulate lab experiments of the VAPEX process. The goal was to understand the mechanisms governing the VAPEX process. Additional work is recommended to expand the VAPEX numerical study using actual field data obtained from Alaska North Slope.

  6. ARM-ACME V: ARM Airborne Carbon Measurements V on the North Slope of Alaska Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Biraud, Sebastien C [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-05-01

    Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO2 and/or CH4) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols and cloud properties in North Slopes of Alaska (NSA) are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections. From June 1 through September 15, 2015, AAF deployed the G1 research aircraft and flew over the North Slope of Alaska (38 flights, 140 science flight hours), with occasional vertical profiling over Prudhoe Bay, Oliktok point, Barrow, Atqasuk, Ivotuk, and Toolik Lake. The aircraft payload included Picarro and Los Gatos Research (LGR) analyzers for continuous measurements of CO2, CH4, H2O, and CO and N2O mixing ratios, and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2, and trace hydrocarbon species). The aircraft payload also include measurements of aerosol properties (number size distribution, total number concentration, absorption, and scattering), cloud properties (droplet and ice size information), atmospheric thermodynamic state, and solar/infrared radiation.

  7. Changes in floral diversities, floral turnover rates, and climates in Campanian and Maastrichtian time, North Slope of Alaska

    Science.gov (United States)

    Frederiksen, N.O.

    1989-01-01

    One-hundred-and-ten angiosperm pollen taxa have been found in upper Campanian to Masstrichtian rocks of the Colville River region, North Slope of Alaska. These are the highest paleolatitude Campanian and Maastrichtian floras known from North America. Total angiosperm pollen diversity rose during the Campanian and declined toward the end of the Maastrichtian. However, anemophilous porate pollen of the Betulaceae-Myricaceae-Ulmaceae complex increased gradually in diversity during the late Campanian and Maastrichtian and into the Paleocene. Turnover of angiosperm taxa was active throughout most of late Campanian and Maastrichtian time; rapid turnover affected mainly the taxa of zoophilous herbs, representing an bundant but ecologically subordinate element of the vegetation. Last appearances of pollen taxa during the late Campanian and Maastrichtian probably represented mainly extinctions rather than emigrations; end- Cretaceous angiosperm extinctions in the North American Arctic began well before the Cretaceous-Tertiary boundary event. The last appearances in the late Maastrichtian took place in bursts; they appear to represent stepwise rather than gradual events, which may indicate the existence of pulses of climatic change particularly in late Maastrichtian time. ?? 1989.

  8. Morphology and lithology of the continental slope north of the Demerara marginal plateau: results from the DRADEM cruise

    Science.gov (United States)

    Basile, Christophe; Girault, Igor; Heuret, Arnauld; Loncke, Lies; Poetisi, Ewald; Graindorge, David; Deverchère, Jacques; Klingelhoefer, Frauke; Frédéric Lebrun, Jean; Perrot, Julie; Roest, Walter

    2017-04-01

    The DRADEM scientific cruise was carried out from July 9th to 21th 2016 on board the R/V Pourquoi Pas?, in the Exclusive Economic Zones of Suriname and French Guiana. This cruise is part of a program dedicated to geological investigations of the continental margin, including the Demerara plateau, following the GUYAPLAC (2003) and IGUANES (2013) cruises, and before the MARGATS cruise (2016). The aims of DRADEM were to map the continental slope of the transform margin north of the Demerara plateau, and to dredge the rocks outcropping on the slope. We completed the bathymetric mapping of the continental slope, including part of the edge of the Demerara plateau. These new bathymetric data confirm the segmentation of the transform margin in three parts with very different morphologies. In addition, two circular structures were interpreted as mud volcanoes, one on the northern edge of the plateau, the other one in the distal part of the Orinoco deep sea fan. Twelve dredges were performed between 4700 and 3500 m water depths. Four from these twelve did not recovered rocks. The eight others recovered variable amounts of rocks, often encrusted, but of various nature: sediments (breccia, coarse sandstones, sandstones with plants debris, sandstones with shells, clayey ooze), micro-granular rocks and metamorphic rocks (including mylonite). The nature of the rocks was determined from macroscopic observation of the altered rocks. Of course, these determinations need to be validated and refined by further studies onshore. In any case, most of these rocks were previously unknown in this area, and they will strongly influence our understanding of the structure and evolution of this margin. They provide evidence for large vertical displacements that brought to the surface some of these rocks, that were formed in a deep setting.

  9. Visitor’s Guide to Oliktok Point Atmospheric Radiation Measurement Climate Research Facility, North Slope of Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Desilets, Darin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Helsel, Fred M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bendure, Al O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lucero, Daniel A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ivey, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dexheimer, Danielle N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-04-01

    The importance of Oliktok Point, Alaska, as a focal point for climate research in the Arctic continues to grow with the addition of a U.S. Department of Energy (DOE) Atmospheric Radiation Monitoring (ARM) Climate Research Facility Mobile Facility (AMF) and the expansion of infrastructure to support airborne measurements. The site hosts a suite of instruments for making multi-year, high-fidelity atmospheric measurements; serves as a base of operations for field campaigns; and contains the only Restricted Airspace and Warning Area in the U.S. Arctic, which enables the use of unmanned aircraft systems. The use of this site by climate researchers involves several considerations, including its remoteness, harsh climate, and location amid the North Slope oilfields. This guide is intended to help visitors to Oliktok Point navigate this unique physical and administrative environment, and thereby facilitate safe and productive operations.

  10. The biogeochemistry of carbon in continental slope sediments: The North Carolina margin

    Energy Technology Data Exchange (ETDEWEB)

    Blair, N.; Levin, L.; DeMaster, D.; Plaia, G.; Martin, C.; Fornes, W.; Thomas, C.; Pope, R.

    1999-12-01

    The responses of the continental slope benthos to organic detritus deposition were studied with a multiple trace approach. Study sites were offshore of Cape Fear (I) and Cape Hatteras (III), N.C. (both 850 m water depth) and were characterized by different organic C deposition rates, macrofaunal densities (III>I in both cases) and taxa. Natural abundances of {sup 13}C and {sup 12}C in particulate organic carbon (POC), dissolved inorganic carbon (DIC) and macrofauna indicate that the reactive organic detritus is marine in origin. Natural abundance levels of {sup 14}C and uptake of {sup 13}C-labeled diatoms by benthic animals indicate that they incorporate a relatively young component of carbon into their biomass. {sup 13}C-labeled diatoms (Thalassiorsira pseudonana) tagged with {sup 210}Pb, slope sediment tagged with {sup 113}Sn and {sup 228}Th-labeled glass beads were emplaced in plots on the seafloor at both locations and the plots were sampled after 30 min., 1-1.5 d and 14 mo. At Site I, tracer diatom was intercepted at the surface primarily by protozoans and surface-feeding annelids. Little of the diatom C penetrated below 2 cm even after 14 months. Oxidation of organic carbon appeared to be largely aerobic. At Site III, annelids were primarily responsible for the initial uptake of tracer. On the time scale of days, diatom C was transported to a depth of 12 cm and was found in animals collected between 5-10 cm. The hoeing of tracer from the surface by the maldanid Praxillela sp. may have been responsible for some of the rapid nonlocal transport. Oxidation of the diatom organic carbon was evident to at least 10 cm depth. Anaerobic breakdown of organic matter is more important at Site III. Horizontal transport, which was probably biologically mediated, was an order of magnitude more rapid than vertical displacement over a year time scale. If the horizontal transport was associated with biochemical transformations of the organic matter, it may represent an

  11. Pore water geochemistry along continental slopes north of the East Siberian Sea: inference of low methane concentrations

    Science.gov (United States)

    Miller, Clint M.; Dickens, Gerald R.; Jakobsson, Martin; Johansson, Carina; Koshurnikov, Andrey; O'Regan, Matt; Muschitiello, Francesco; Stranne, Christian; Mörth, Carl-Magnus

    2017-06-01

    Continental slopes north of the East Siberian Sea potentially hold large amounts of methane (CH4) in sediments as gas hydrate and free gas. Although release of this CH4 to the ocean and atmosphere has become a topic of discussion, the region remains sparingly explored. Here we present pore water chemistry results from 32 sediment cores taken during Leg 2 of the 2014 joint Swedish-Russian-US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions (SWERUS-C3) expedition. The cores come from depth transects across the slope and rise extending between the Mendeleev and the Lomonosov ridges, north of Wrangel Island and the New Siberian Islands, respectively. Upward CH4 flux towards the seafloor, as inferred from profiles of dissolved sulfate (SO42-), alkalinity, and the δ13C of dissolved inorganic carbon (DIC), is negligible at all stations east of 143° E longitude. In the upper 8 m of these cores, downward SO42- flux never exceeds 6.2 mol m-2 kyr-1, the upward alkalinity flux never exceeds 6.8 mol m-2 kyr-1, and δ13C composition of DIC (δ13C-DIC) only moderately decreases with depth (-3.6 ‰ m-1 on average). Moreover, upon addition of Zn acetate to pore water samples, ZnS did not precipitate, indicating a lack of dissolved H2S. Phosphate, ammonium, and metal profiles reveal that metal oxide reduction by organic carbon dominates the geochemical environment and supports very low organic carbon turnover rates. A single core on the Lomonosov Ridge differs, as diffusive fluxes for SO42- and alkalinity were 13.9 and 11.3 mol m-2 kyr-1, respectively, the δ13C-DIC gradient was 5.6 ‰ m-1, and Mn2+ reduction terminated within 1.3 m of the seafloor. These are among the first pore water results generated from this vast climatically sensitive region, and they imply that abundant CH4, including gas hydrates, do not characterize the East Siberian Sea slope or rise along the investigated depth transects. This contradicts previous modeling and discussions, which

  12. The North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) cart site begins operation: Collaboration with SHEBA and FIRE

    Energy Technology Data Exchange (ETDEWEB)

    Zak, D. B.; Church, H.; Ivey, M.; Yellowhorse, L.; Zirzow, J.; Widener, K. B.; Rhodes, P.; Turney, C.; Koontz, A.; Stamnes, K.; Storvold, R.; Eide, H. A.; Utley, P.; Eagan, R.; Cook, D.; Hart, D.; Wesely, M.

    2000-04-04

    Since the 1997 Atmospheric Radiation Measurement (ARM) Science Team Meeting, the North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) Cloud and Radiation Testbed (CART) site has come into being. Much has happened even since the 1998 Science Team Meeting at which this paper was presented. To maximize its usefulness, this paper has been updated to include developments through July 1998.

  13. Traditional Ecological Knowledge of Stem Concepts in Informal and Place-Based Western Educational Systems: Lessons from the North Slope, Alaska

    Science.gov (United States)

    Nicholas-Figueroa, Linda

    2017-01-01

    Upon regaining the right to direct education at the local level, the North Slope Borough (NSB) of Alaska incorporated Inupiat educational philosophies into the educational system. The NSB in partnership with the University of Alaska Fairbanks established Ilisagvik College, the only tribal college in Alaska. Ilisagvik College seeks to broaden…

  14. North-south comparison of springtime dark slope structures on Mars, and the possibility of liquid water

    Science.gov (United States)

    Kereszturi, A.; Berczi, Sz.; Horvath, A.; Ganti, T.; Kuti, A.; Pocs, T.; Sik, A.; Szathmary, E.

    2008-09-01

    Introduction Various polar seasonal surface albedo structures were analyzed by several authors in the past [1, 2, 3, 4, 5, 6, 7, 8, 8, 9], partly in connection with the possibility of liquid water. In our previous work [10] we identified two groups of slope streaks emanating form Dark Dune Spots of polar dunes, which grow in size and number during spring with the advancement of the season. The diffuse shaped group appears earlier and formed probably by CO2 geysers [8]. The confine shaped group appears in a later seasonal phase, when the temperature is higher. They are probably connected with exposed water-ice on the surface, and may formed by the seepage of undercooled interfacial water on microscopic scale [11]. Methods For the analysis of northern slope structures we used MGS MOC, MRO HiRISE images, and MRG TES data [12] using the "vanilla" software. Temperature data show annual trend, and were derived for daytime. Note that the surface temperature values have spatial resolution around 3 km, and they can be taken only as a rough approach of the surface temperature of the whole dune complex, and not different parts of it. Discussion The target area of the analysis was (84N 233E) in the northern circumpolar sand sea, with 300-500 m diameter overlapping dunes. We searched for springtime confined and elongated dark slope streaks, similar to those, which we observed at south. Basic similarities between northern and southern structures are: 1. streaks always emanate from Dark Dune Spots in downward direction, 2. streaks are present in local spring, when the temperature is above the CO2 buffered level, suggesting there are parts of the surface without CO2 ice, where possibly H2O ice is exposed (Fig. 1.), 4. the streaks show branching pattern (Fig. 2.). Basic differences between the northern and southern structures: 1. at north there is a dark annulus around the Dark Dune Spots, which is absent at south, 2. there are fewer and fainter diffuse streaks of gas jet activity

  15. Experimental study of solvent-based emulsion injection to enhance heavy oil recovery in Alaska North Slope area

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, F.; Mamora, D. [Texas A and M Univ., College Station, TX (United States)

    2010-07-01

    This study examined the feasibility of using a chemical enhanced oil recovery method to overcome some of the technical challenges associated with thermal recovery in the Alaska North Slope (ANS). This paper described the second stage research of an experimental study on nano-particle and surfactant-stabilized solvent-based emulsions for the ANS area. Four successful core flood experiments were performed using heavy ANS oil. The runs included water flooding followed by emulsion flooding; and pure emulsion injection core flooding. The injection rate and core flooding temperature remained constant and only 1 PV micro-emulsion was injected after breakthrough under water flooding or emulsion flooding. Oil recovery increased by 26.4 percent from 56.2 percent original oil in place (OOIP) with waterflooding to 82.6 percent OOIP with injection of emulsion following water flooding. Oil recovery was slightly higher with pure emulsion flooding, at 85.8 percent OOIP. The study showed that low permeability generally resulted in a higher shear rate, which is favourable for in-situ emulsification and higher displacement efficiency. 11 refs., 4 tabs., 20 figs.

  16. Lagrangian circulation of the North Atlantic Central Water over the abyssal plain and continental slopes of the Bay of Biscay: description of selected mesoscale features

    Directory of Open Access Journals (Sweden)

    Alain Serpette

    2006-06-01

    Full Text Available Between 1994 and 2001, several experiments (ARCANE, SEFOS, INTERAFOS were conducted to directly measure the general and mesoscale Lagrangian circulations over the Bay of Biscay abyssal plain and slopes. Two levels (~100 m and ~450 m were selected to cover the North Atlantic Central Water range. Two types of Lagrangian instruments, drogued surface drifters tracked by satellite (Surdrift and acoustically tracked subsurface floats (Rafos and Marvor, were used. Overall, more than 36 instrument-years were collected in the Bay of Biscay region (43-49°N, 01-12°W. The weak general circulation in the Bay of Biscay is seen to be highly influenced by the occurrence of several mesoscale coherent features, notably slope currents and eddies, and these affect the exchanges between the abyssal plain and the slopes. The objective of this paper is to depict some specific examples of the observed mesoscale field. Selected float trajectories are shown and used to discuss observations of slope currents and of both anticyclonic and cyclonic eddies. Slope currents exhibit alternation of poleward and equatorward directions, depending on both the period and the geographic area considered. Although the generation process of mesoscale eddies is difficult to observe unambiguously from Lagrangian instruments, eddies are nevertheless ubiquitous over the abyssal plain. Some characteristics of the observed cyclonic and anticyclonic eddies are presented. Smaller anticyclones, localised over the outer shelf and interpreted in terms of ajustment of slope water intrusions, are also depicted.

  17. Alaskan Commodities Irradiation Project

    International Nuclear Information System (INIS)

    Zarling, J.P.; Swanson, R.B.; Logan, R.R.

    1988-01-01

    The ninety-ninth US Congress commissioned a six-state food irradiation research and development program to evaluate the commercial potential of this technology. Hawaii, Washington, Iowa, Oklahoma and Florida as well as Alaska have participated in the national program; various food products including fishery products, red meats, tropical and citrus fruits and vegetables have been studied. The purpose of the Alaskan study was to review and evaluate those factors related to the technical and economic feasibility of an irradiator in Alaska. This options analysis study will serve as a basis for determining the state's further involvement in the development of food irradiation technology. 40 refs., 50 figs., 53 tabs

  18. The relationship between organic carbon and methanesulfonic acid at two sites on the North Slope of Alaska over four summers

    Science.gov (United States)

    Moffett, C. E.; Barrett, T. E.; Gunsch, M.; Pratt, K.; Sheesley, R. J.

    2017-12-01

    Aerosols in the Arctic have large potential impacts on the radiative balance via direct and indirect effect such as scattering solar radiation and acting as cloud condensation nuclei (CCN). Marine aerosols, consisting of both inorganic particles and organic carbon (OC) contribute to these effects greatly. There are many sources of OC in the atmosphere such as oil and gas emissions, fossil fuel combustion, biomass burning, and biogenic sources, which includes marine aerosols. Dimethyl sulfide (DMS), a gas produced by phytoplankton, is photo oxidized in the atmosphere to form methanesulfonic acid (MSA). MSA can be important in forming cloud condensation nuclei, especially in remote regions such as the Arctic. While MSA has been studied in the Arctic, its relationship to particulate OC is not well understood. Total suspended particulate matter samples were collected at two sites, Utqiaġvik, AK, and Oliktok Point, AK, during the summers of 2012, 2015, 2016, and 2017. Utqiaġvik, AK, is located on the northern most point of the United States with a population of 4,581. The site is 7.4 km north of the village of Utqiaġvik. Oliktok Point, AK, is 300 km south east of Utqiaġvik in a region of intense petroleum development. Potential marine biogenic inputs to gas and particle phase organics include phytoplankton and algae in the Arctic Ocean. Terrestrial sources may also impact biogenic OC for these North Slope sites. For this study our primary focus is the relationship between MSA and OC. In addition we are investigating the variability in summertime organic acid concentrations and relationship with OC and MSA. Samples were analyzed for OC and organic and inorganic ions including MSA. MSA may exist primarily in the smaller size fraction so the method was modified to measure it in the presence of high chloride. Measurements of MSA were also completed using an aerosol time-of-flight mass spectrometer (ATOFMS). Preliminary results show that MSA concentrations follow

  19. Late Quaternary environmental changes inferred from stable carbon, nitrogen and oxygen isotope values at Teshekpuk Lake, North Slope, Alaska

    Science.gov (United States)

    Randall, J. J.; Booth, A. L.; Wooller, M. J.; Jones, B. M.; Gaglioti, B.

    2012-12-01

    Global surface air temperatures increased by ~0.74°C between 1906-2005, with average temperatures in the Arctic increasing at almost twice the rate as the rest of the planet. The Arctic Coastal Plain of Alaska is particularly susceptible and responsive to these fluctuations in climate. Better understanding both short- and long-term climate variability is important as this ecosystem provides food and habitat for hundreds of thousands of migratory birds and caribou. Despite the ecological importance of the Arctic Coastal Plain, relatively few studies exist that provide multi-proxy paleoclimatic data for the region and thus the rate at which climate and ecosystems have changed during the past century lack a longer term context. Here we present stable carbon and nitrogen isotope values from the analysis of bulk organic matter in samples from a ~6 m sediment core from Teshekpuk Lake, 80 miles southeast of Barrow, Alaska. AMS 14C dates on a nearby core indicate a basal age of ~15 kyr. The relatively low C/N values (mean base of the core to peaks of ~-23‰ between ~10 and 8 kyr, inferring highs in lake production during this time. We also present stable oxygen isotope values from analyses of chironomid and aquatic invertebrate chitin preserved in the core. Non-biting midges in the family Chironomidae begin their lifecycles in freshwater. During their larval stages chironomids synthesize and molt chitinous head capsules. These head capsules record the oxygen isotopic composition of the lake water present at the time of synthesis, and are well preserved in lake sediments. These isotopic results are interpreted in terms of other recent isotope data from the north slope of Alaska in addition to a pollen reconstruction from the same core and their implications in terms of past environmental changes.

  20. The 2015 Spring Freshet and Its Effects on the Alaskan Beaufort Sea

    Science.gov (United States)

    Kasper, J.; Trefry, J. H.; Fox, A. L.; Savoie, M.; Fox, S. L.; Lawley, G.; Trocine, R. P.; Shipton, P.

    2016-02-01

    In 2015, a unique set of measurements were collected from the landfast ice of the Alaskan Beaufort Sea, as the buoyant plume resulting from the spring freshet of the largest Arctic Alaska river, the Colville, spread beneath the sea ice covering Harrison Bay. Velocities of both the plume and the ambient shelf water beneath the plume were measured as well as salinity and temperature, particle size and concentration. A suite of geochemical measurements including dissolved oxygen, pH, total suspended solids, dissolved and particulate metals N, P, C and δ18O were made at the same time. In addition, the Colville as well as the nearby Sagavanirktok and Kuparak Rivers were sampled for many of these same parameters. This comprehensive set of measurements allows us to describe in detail the dynamics of the spring 2015 under ice freshet. The 2015 freshet on the North Slope of Alaska was marked by the rapid onset of melt simultaneously across the entire slope resulting in melt water rapidly spreading both over and under the sea ice north from the coast. Consistent with simple numerical models, the thickness of the buoyant under ice plume increased rapidly with time as well.

  1. C-N-P interactions control climate driven changes in regional patterns of C storage on the North Slope of Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yueyang; Rocha, Adrian; Rastetter, Edward; Shaver, Gaius; Mishra, U.; Zhuang, Qianlai; Kwiatkowski, Bonnie

    2016-01-01

    As climate warms, changes in the carbon (C) balance of arctic tundra will play an important role in the global C balance. The C balance of tundra is tightly coupled to the nitrogen (N) and phosphorus (P) cycles because soil organic matter is the principal source of plant-available nutrients and determines the spatial variation of vegetation biomass across the North Slope of Alaska. Warming will accelerate these nutrient cycles, which should stimulate plant growth.

  2. A coupled approach to spatially derived parameters necessary for ecosystem modeling on the North Slope of Alaska: Appendix A. Final report, March 1, 1989--February 28, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, G.W.; Day, R.L.; Pollack, J. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Agronomy

    1993-12-01

    This study concerned an investigation of ecosystem dynamics in several small study sites in the North Slope region of Alaska. The scope of the proposed research is to quantitatively determine spatial interrelationships between landform geometry within these study areas and such ecologically important factors as vegetation type, depth-to-permafrost, hydraulic conductivity and incoming solar radiation. Extrapolation techniques developed and terrain-related data generated as a result of this research will augment R4D Phase II goals which relate to running the General Arctic Simulac (GAS) model (and associated ecosystem models) at different locations on the North Slope. In particular, Penn State has contributed significantly to extrapolation efforts by developing techniques which can be used to initialize conditions for model input either through direct measurement (e.g., slope and aspect) and GIS-based simulation models (e.g., drainage basin characterization). As stated in the R4D Phase II Research Plan, the long-term objectives of this program are: (1) to determine effects and to develop models based on ecosystem disturbances commonly created by energy development so that appropriate, cost-effective measures can be utilized to minimize deleterious disturbances; and (2) to extend the results to other arctic and alpine areas which are important because of likely impact from energy development. It is this second long-term objective which relates most directly to Penn State`s work.

  3. A regional assessment of potential environmental hazards to and limitations on petroleum development of the Southeastern United States Atlantic continental shelf, slope, and rise, offshore North Carolina

    Science.gov (United States)

    Popenoe, Peter; Coward, E.L.; Cashman, K.V.

    1982-01-01

    More than 11,000 km of high-resolution seismic-reflection data, 325 km of mid-range sidescan-sonar data, and 500 km of long-range sidescan-sonar data were examined and used to construct an environmental geology map of the Continental Shelf, Slope, and Rise for the area of the U.S. Atlantic margin between lats. 32?N. and 37?N. Hardgrounds and two faults described in previous literature also are shown on the map. On the Continental Shelf, at least two faults, the Helena Banks fault and the White Oak lineament, appear to be tectonic in origin. However, a lack of historical seismicity associated with these faults indicates that they are probably not active at the present time. Hardgrounds are widely scattered but are most abundant in Onslow Bay. Although paleostream channels are common nearshore, they do not appear to be common on the central and outer shelf except off Albemarle Sound where extensive Pleistocene, Pliocene, and late Miocene channels extend across the shelf. Mobile bottom sediments are confined mainly to the shoals off Cape Romain, Cape Fear, Cape Lookout, and Cape Hatteras. Elsewhere the sand cover is thin, and older more indurated rocks are present in subcrop. No slope-instability features were noted on the Florida-Hatteras slope off North Carolina. The lack of features indicates that this slope is relatively stable. Evidence for scour by strong currents is ubiquitous on the northern Blake Plateau although deep-water reefs are sparse. The outer edge of the plateau is dominated by a major growth fault and numerous splay and antithetic faults. These faults are the product of salt tectonism in the Carolina trough and thus are not associated with seismicity. Displacements observed near the sea floor and breached diapirs offshore indicate that the main fault is still moving. Associated with the faults are collapse features that are interpreted to be caused by karst solution and cavernous porosity in Eocene and Oligocene limestones at depth. Major slumps

  4. The Characteristic and Genesis of Volcanic Ash Soil in the North Slope Toposequence of Kawi Mountain in Malang Regency

    Directory of Open Access Journals (Sweden)

    A.N. Putra

    2015-07-01

    Full Text Available The volcanic ash soil in Kawi Mountain is composed by the amorphous materials consist of allophane, imogolite and ferrihydrite. Results of previous study showed that the phosphate retention in all soil profiles of northern slope toposequence of Kawimountain was less than 85%, yet the phosphate retention of volcanic ash soils is usually > 85 %. This raised a question that there is a different characteristics of soil in the northern slope tosequence of the Kawi Mountain compared to the other places. This research was conducted to study soil characteristics, mineral contents, and genesis processessoccuring in soil on the northern slope toposequence of Kawi Mountain. 5 pedons between high elevation and low elevation (P1, P2, P3, P4 and P5 to identified the soil characteristics. The Al, Fe, and Si extracted by acid oxalate, natrium pyrophosphate, and dithionite citrate to calculate the amorphous mineral content. The results show that. The results showed that there is a different in terms of the thickness of the A horizon, the C organic content and the soil acidity level that mainly found in P3 and P4 profiles. The most important soil genesis processess in the formation of the volcanic ash soils were likely clay illuviation (P5, melanization and braunification (P3, littering (P1 and the reduction of andic soil properties from the upper slope (P1 profile up to the lower slope (P5 profile.

  5. The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing

    Science.gov (United States)

    Rocha, Adrian V.; Loranty, Michael M.; Higuera, Phil E.; Mack, Michelle C.; Hu, Feng Sheng; Jones, Benjamin M.; Breen, Amy L.; Rastetter, Edward B.; Goetz, Scott J.; Shaver, Gus R.

    2012-12-01

    Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required.

  6. The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing

    International Nuclear Information System (INIS)

    Rocha, Adrian V; Loranty, Michael M; Higuera, Phil E; Mack, Michelle C; Hu Fengsheng; Jones, Benjamin M; Breen, Amy L; Rastetter, Edward B; Shaver, Gus R; Goetz, Scott J

    2012-01-01

    Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required. (letter)

  7. The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing

    Science.gov (United States)

    Rocha, Adrian V.; Loranty, Michael M.; Higuera, Phil E.; Mack, Michelle C.; Hu, Feng Sheng; Jones, Benjamin M.; Breen, Amy L.; Rastetter, Edward B.; Goetz, Scott J.; Shaver, Gus R.

    2012-01-01

    Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required.

  8. Assessment of primary production and optical variability in shelf and slope waters near Cape Hatteras, North Carolina. Final project report

    Energy Technology Data Exchange (ETDEWEB)

    Redalje, Donald G.; Lohrenz, Stevern E.

    2001-02-12

    In this project we determined primary production and optical variability in the shelf and slope waters off of Cape Hatteras, N.C. These processes were addressed in conjunction with other Ocean Margins Program investigators, during the Spring Transition period and during Summer. We found that there were significant differences in measured parameters between Spring and Summer, enabling us to develop seasonally specific carbon production and ecosystem models as well as seasonal and regional algorithm improvements for use in remote sensing applications.

  9. Benthic Community Structure and Sediment Geochemical Properties at Hydrocarbon Seeps Along the Continental Slope of the Western North Atlantic

    Science.gov (United States)

    Demopoulos, A. W.; Bourque, J. R.; Brooke, S.

    2015-12-01

    Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410-450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared

  10. Traditional Ecological Knowledge of Stem Concepts in Informal and Place-Based Western Educational Systems: Lessons from the North Slope, Alaska

    Science.gov (United States)

    Nicholas-Figueroa, Linda

    Upon regaining the right to direct education at the local level, the North Slope Borough (NSB) of Alaska incorporated Inupiat educational philosophies into the educational system. The NSB in partnership with the University of Alaska Fairbanks established Ilisagvik College, the only tribal college in Alaska. Ilisagvik College seeks to broaden science, technology, engineering, and mathematical education on the North Slope. Incorporation of place-based and informal lessons with traditional ecological knowledge engages students in education. Ilisagvik hosted a 2-week climate change program from 2012 - 2015 for high school and middle school students that examined climate science and the effects of a warming climate on the local environment from a multitude of perspectives from scientists, Inupiat Elders, and instructor-led field trips. Pre-assessments and post-assessments using the Student Assessment of Learning Gains tool measured students' interests and conceptual understanding. Students developed and enhanced their understanding of science concepts and, at the end of the program, could articulate the impact of climatic changes on their local environment. Similarly, methods to incorporate Indigenous knowledge into research practices have been achieved, such as incorporating field trips and discussion with Elders on the importance of animal migration, whale feeding patterns, and the significance of sea-ice conditions, which are important community concerns.

  11. Modified method for estimating petroleum source-rock potential using wireline logs, with application to the Kingak Shale, Alaska North Slope

    Science.gov (United States)

    Rouse, William A.; Houseknecht, David W.

    2016-02-11

    In 2012, the U.S. Geological Survey completed an assessment of undiscovered, technically recoverable oil and gas resources in three source rocks of the Alaska North Slope, including the lower part of the Jurassic to Lower Cretaceous Kingak Shale. In order to identify organic shale potential in the absence of a robust geochemical dataset from the lower Kingak Shale, we introduce two quantitative parameters, $\\Delta DT_\\bar{x}$ and $\\Delta DT_z$, estimated from wireline logs from exploration wells and based in part on the commonly used delta-log resistivity ($\\Delta \\text{ }log\\text{ }R$) technique. Calculation of $\\Delta DT_\\bar{x}$ and $\\Delta DT_z$ is intended to produce objective parameters that may be proportional to the quality and volume, respectively, of potential source rocks penetrated by a well and can be used as mapping parameters to convey the spatial distribution of source-rock potential. Both the $\\Delta DT_\\bar{x}$ and $\\Delta DT_z$ mapping parameters show increased source-rock potential from north to south across the North Slope, with the largest values at the toe of clinoforms in the lower Kingak Shale. Because thermal maturity is not considered in the calculation of $\\Delta DT_\\bar{x}$ or $\\Delta DT_z$, total organic carbon values for individual wells cannot be calculated on the basis of $\\Delta DT_\\bar{x}$ or $\\Delta DT_z$ alone. Therefore, the $\\Delta DT_\\bar{x}$ and $\\Delta DT_z$ mapping parameters should be viewed as first-step reconnaissance tools for identifying source-rock potential.

  12. GeoFORCE Alaska: Four-Year Field Program Brings Rural Alaskan High School Students into the STEM Pipeline

    Science.gov (United States)

    Fowell, S. J.; Rittgers, A.; Stephens, L.; Hutchinson, S.; Peters, H.; Snow, E.; Wartes, D.

    2016-12-01

    GeoFORCE Alaska is a four-year, field-based, summer geoscience program designed to raise graduation rates in rural Alaskan high schools, encourage participants to pursue college degrees, and increase the diversity of Alaska's technical workforce. Residents of predominantly Alaska Native villages holding degrees in science, technology, engineering, or math (STEM) bring valuable perspectives to decisions regarding management of cultural and natural resources. However, between 2010 and 2015 the average dropout rate for students in grades 7-12 was 8.5% per year in the North Slope School District and 7% per year in the Northwest Arctic School District. 2015 graduation rates were 70% and 75%, respectively. Statewide statistics highlight the challenge for Alaska Native students. During the 2014-2015 school year alone 37.6% of Alaska Native students dropped out of Alaskan public schools. At the college level, Alaska Native students are underrepresented in University of Alaska Fairbanks (UAF) science departments. Launched in 2012 by UAF in partnership with the longstanding University of Texas at Austin program, GeoFORCE applies the cohort model, leading the same group of high school students on geological field academies during four consecutive summers. Through a combination of active learning, teamwork, and hands-on projects at spectacular geological locations, students gain academic skills and confidence that facilitate high school and college success. To date, GeoFORCE Alaska has recruited two cohorts. 78% of these students identify as Alaska Native, reflecting community demographics. The inaugural cohort of 18 students from the North Slope Borough completed the Fourth-Year Academy in summer 2015. 94% of these students graduated from high school, at least 72% plan to attend college, and 33% will major in geoscience. A second cohort of 34 rising 9th and 10th graders entered the program in 2016. At the request of corporate sponsors, this cohort was recruited from both the

  13. Phase Behavior, Solid Organic Precipitation, and Mobility Characterization Studies in Support of Enhanced Heavy Oil Recovery on the Alaska North Slope

    Energy Technology Data Exchange (ETDEWEB)

    Shirish Patil; Abhijit Dandekar; Santanu Khataniar

    2008-12-31

    The medium-heavy oil (viscous oil) resources in the Alaska North Slope are estimated at 20 to 25 billion barrels. These oils are viscous, flow sluggishly in the formations, and are difficult to recover. Recovery of this viscous oil requires carefully designed enhanced oil recovery processes. Success of these recovery processes is critically dependent on accurate knowledge of the phase behavior and fluid properties, especially viscosity, of these oils under variety of pressure and temperature conditions. This project focused on predicting phase behavior and viscosity of viscous oils using equations of state and semi-empirical correlations. An experimental study was conducted to quantify the phase behavior and physical properties of viscous oils from the Alaska North Slope oil field. The oil samples were compositionally characterized by the simulated distillation technique. Constant composition expansion and differential liberation tests were conducted on viscous oil samples. Experiment results for phase behavior and reservoir fluid properties were used to tune the Peng-Robinson equation of state and predict the phase behavior accurately. A comprehensive literature search was carried out to compile available compositional viscosity models and their modifications, for application to heavy or viscous oils. With the help of meticulously amassed new medium-heavy oil viscosity data from experiments, a comparative study was conducted to evaluate the potential of various models. The widely used corresponding state viscosity model predictions deteriorate when applied to heavy oil systems. Hence, a semi-empirical approach (the Lindeloff model) was adopted for modeling the viscosity behavior. Based on the analysis, appropriate adjustments have been suggested: the major one is the division of the pressure-viscosity profile into three distinct regions. New modifications have improved the overall fit, including the saturated viscosities at low pressures. However, with the limited

  14. Variability of slope current positioning from space: Application to the Northern Current in the North Western Mediterranean Sea

    Science.gov (United States)

    Bouffard, Jerome; Marmain, Julien; Bosse, Anthony; Petrenko, Anne; Forget, Philippe; Doglioli, Andrea; Testor, Pierre; Mortier, Laurent

    The space-time variability of slope currents plays a key role on the across-shore transport of natural and anthropogenic elements. It is therefore of critical importance to monitor the front positioning associated with these hydrodynamical features in a synoptic way, in particular along densely populated coasts such as the littoral zone of the Mediterranean Sea. Our paper proposes to address this issue by developing a new multi-satellite altimetric-based approach aiming at monitoring the long-term behaviour of the Northern Current, from 2002 to 2012. Our method is assessed by direct comparisons with observations from glider transects of the current, coastal HF radar and a moored current-meter. Despite important limitations due to the current altimetric sampling and a lower accuracy in the 50 km coastal band, we demonstrate the ability of our new method to characterize the variability of the front positioning from intra-seasonal to annual scales. We particularly focus the analysis on the Gulf of Lion, where the distance between the mean geostrophic flow and the coast allows a good detection of high frequency signals associated with slope current intrusions over the continental shelf. We show that such abrupt events generally occur in autumn and are forced by heterogeneous, strong and rapidly evolving south-easterly wind events. This work is based on an original exploitation of the existing along-track altimetry data and paves the way for new applications within the prospect of the next satellite generation whose technology is more suitable for coastal studies.

  15. Use of summer habitat by caribou on the north slope of a mountain near the Macmillan Pass, N.W.T.

    Directory of Open Access Journals (Sweden)

    James F. Quayle

    1996-01-01

    Full Text Available Habitat use by woodland caribou was investigated by counting pellet-groups, sampling phytomass, and evaluating topography in nine habitat-types on the north slope of an unnamed mountain near Macmillan Pass, N.W.T. Caribou pellets were most abundant in high elevation habitat-types, and pellet density was greatest in an alpine Lichen-Grass habitat-type with a slope of <1°. The high density of pellets in alpine areas may have resulted from of the use of cool, windy, alpine habitats by caribou seeking relief from insect harassment. There were no apparent relationships between pellet abundance, and phytomass of mosses, lichens, or graminoids, possibly as a result of caribou feeding and defecating in different habitats. The occurrence of pellets with a coalesced morphology in the barren Lichen-Grass habitat-type provided indirect evidence in support of a feeding cycle, whereby caribou visit lush habitats to feed, and return to open, alpine habitats to rest and ruminate.

  16. InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

    Science.gov (United States)

    Rykhus, Russell P.; Lu, Zhong

    2008-01-01

    Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

  17. Trophic ecology of Lampanyctus crocodilus on north-west Mediterranean Sea slopes in relation to reproductive cycle and environmental variables.

    Science.gov (United States)

    Fanelli, E; Papiol, V; Cartes, J E; Rodriguez-Romeu, O

    2014-06-01

    This study examined the population structure, reproductive cycle and feeding pattern of the lanternfish Lampanyctus crocodilus in the Balearic Basin (north-west Mediterranean Sea) from a depth of 450 to 1800 m and at a seasonal scale. Juveniles were mainly located at shallower depths, but also at deepest stations in autumn, while adults mostly inhabited intermediate depths with their centre of population density (CPD) located at 800-1000 m of depth. The migration of adults to deeper depths was detected in late summer to autumn, probably linked to the occurrence of nepheloid layers at c. 1200 m, which in turn enhances the biomass of the zooplankton prey. The diet was mainly based on euphausiids and mysids, with marked seasonal variations both on the upper (450-800 m) and lower (1000-1800 m), where suprabenthic gammariids and pelagic decapods were also dominant. Stomach fullness increased from winter to autumn on the US, while it had a maximum in spring on the LS, in parallel with high consumption of gelatinous zooplankton, which is probably more available after the phytoplankton bloom in late winter. Reproduction occurred in winter, confirmed by the higher percentage of mature females and high gonadosomatic indices (I(G)) at both depth ranges. Hepatosomatic indices (I(H)) showed an inverse trend to I(G) on the US, except in autumn, and was almost parallel on the LS, probably attributable to the migration of adults, which determined different temporal schemes in energy use and storage for reproduction on the US v. LS. Consistent with the different patterns observed at the two depth ranges, environmental drivers of fullness (i.e. feeding intensity) and I(G) (as a proxy of reproductive cycle) differed on the US and LS. The biomass of mysids and euphausiids was the greatest explanatory variables of fullness on the US and LS, pointing to the increasing feeding intensity when a resource was more available. I(H) also explained fullness, suggesting that greater

  18. Integrating GIS-based geologic mapping, LiDAR-based lineament analysis and site specific rock slope data to delineate a zone of existing and potential rock slope instability located along the grandfather mountain window-Linville Falls shear zone contact, Southern Appalachian Mountains, Watauga County, North Carolina

    Science.gov (United States)

    Gillon, K.A.; Wooten, R.M.; Latham, R.L.; Witt, A.W.; Douglas, T.J.; Bauer, J.B.; Fuemmeler, S.J.

    2009-01-01

    Landslide hazard maps of Watauga County identify >2200 landslides, model debris flow susceptibility, and evaluate a 14km x 0.5km zone of existing and potential rock slope instability (ZEPRSI) near the Town of Boone. The ZEPRSI encompasses west-northwest trending (WNWT) topographic ridges where 14 active/past-active rock/weathered rock slides occur mainly in rocks of the Grandfather Mountain Window (GMW). The north side of this ridgeline is the GMW / Linville Falls Fault (LFF) contact. Sheared rocks of the Linville Falls Shear Zone (LFSZ) occur along the ridge and locally in the valley north of the contact. The valley is underlain principally by layered granitic gneiss comprising the Linville Falls/Beech Mountain/Stone Mountain Thrust Sheet. The integration of ArcGIS??? - format digital geologic and lineament mapping on a 6m LiDAR (Light Detecting and Ranging) digital elevation model (DEM) base, and kinematic analyses of site specific rock slope data (e.g., presence and degree of ductile and brittle deformation fabrics, rock type, rock weathering state) indicate: WNWT lineaments are expressions of a regionally extensive zone of fractures and faults; and ZEPRSI rock slope failures concentrate along excavated, north-facing LFF/LFSZ slopes where brittle fabrics overprint older metamorphic foliations, and other fractures create side and back release surfaces. Copyright 2009 ARMA, American Rock Mechanics Association.

  19. Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Stern, Laura A.; Lorenson, T.D.; Pinkston, John C.

    2011-01-01

    Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA–DOE–USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5 m to 760.1 m depth, and sections investigated here were retrieved from 619.9 m and 661.0 m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70–75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20–120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas.

  20. Provenance of Holocene sediment on the Chukchi-Alaskan margin based on combined diffuse spectral reflectance and quantitative X-Ray Diffraction analysis

    Science.gov (United States)

    Ortiz, J.D.; Polyak, L.; Grebmeier, J.M.; Darby, D.; Eberl, D.D.; Naidu, S.; Nof, D.

    2009-01-01

    Sediment clay and silt mineral assemblages provide an excellent means of assessing the provenance of fine-grained Arctic sediment especially when a unique mineral assemblage can be tied to specific source areas. The diffuse spectral reflectance (DSR) first derivative measurements and quantitative X-Ray Diffraction (qXRD) on a high-resolution sediment core from the continental slope north of Alaska constrain the sediment mineralogy. DSR results are augmented by measurements on several adjacent cores and compared to surface sediment samples from the northern Alaskan shelf and slope. Using Principal Component Analysis (PCA), we infer that the three leading DSR modes relate to mixtures of smectite + dolomite, illite + goethite, and chlorite + muscovite. This interpretation is consistent with the down core qXRD results. While the smectite + dolomite, and illite + goethite factors show increased variability down core, the chlorite + muscovite factor had highest positive loadings in the middle Holocene, between ca. 6.0 and 3.6??ka. Because the most likely source of the chlorite + muscovite suite in this vicinity lies in the North Pacific, we argue that the oscillations in chlorite + muscovite values likely reflect an increase in the inflow of Pacific water to the Arctic through the Bering Strait. The time interval of this event is associated in other parts of the globe with a non-linear response of the climate system to the decrease in insolation, which may be related to changes in water exchange between the Pacific and Arctic Ocean. ?? 2009 Elsevier B.V.

  1. Assessing the Utility of Temporally Dynamic Terrain Indices in Alaskan Moose Resource Selection

    Science.gov (United States)

    Jennewein, J. S.; Hebblewhite, M.; Meddens, A. J.; Gilbert, S.; Vierling, L. A.; Boelman, N.; Eitel, J.

    2017-12-01

    The accelerated warming in arctic and boreal regions impacts ecosystem structure and plant species distribution, which have secondary effects on wildlife. In summer months, moose (Alces alces) are especially vulnerable to changes in the availability and quality of forage and foliage cover due to their thermoregulatory needs and high energetic demands post calving. Resource selection functions (RSFs) have been used with great success to model such tradeoffs in habitat selection. Recently, RSFs have expanded to include more dynamic representations of habitat selection through the use of time-varying covariates such as dynamic habitat indices. However, to date few studies have investigated dynamic terrain indices, which incorporate long-term, highly-dynamic meteorological data (e.g., albedo, air temperature) and their utility in modeling habitat selection. The purpose of this study is to compare two dynamic terrain indices (i.e., solar insolation and topographic wetness) to their static counterparts in Alaskan moose resource selection over a ten-year period (2008-2017). Additionally, the utility of a dynamic wind-shelter index is assessed. Three moose datasets (n=130 total), spanning a north-to-south gradient in Alaska, are analyzed independently to assess location-specific resource selection. The newly-released, high-resolution Arctic Digital Elevation Model (5m2) is used as the terrain input into both dynamic and static indices. Dynamic indices are programmed with meteorological data from the North American Regional Analysis (NARR) and NASA's Goddard Earth Sciences Data and Information Services Center (GES-DISC) databases. Static wetness and solar insolation indices are estimated using only topographic parameters (e.g., slope, aspect). Preliminary results from pilot analyses suggest that dynamic terrain indices may provide novel insights into resource selection of moose that could not be gained when using static counterparts. Future applications of such dynamic

  2. Source Characterization and Temporal Variation of Methane Seepage from Thermokarst Lakes on the Alaska North Slope in Response to Arctic Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2012-09-30

    The goals of this research were to characterize the source, magnitude and temporal variability of methane seepage from thermokarst lakes (TKL) within the Alaska North Slope gas hydrate province, assess the vulnerability of these areas to ongoing and future arctic climate change and determine if gas hydrate dissociation resulting from permafrost melting is contributing to the current lake emissions. Analyses were focused on four main lake locations referred to in this report: Lake Qalluuraq (referred to as Lake Q) and Lake Teshekpuk (both on Alaska's North Slope) and Lake Killarney and Goldstream Bill Lake (both in Alaska's interior). From analyses of gases coming from lakes in Alaska, we showed that ecological seeps are common in Alaska and they account for a larger source of atmospheric methane today than geologic subcap seeps. Emissions from the geologic source could increase with potential implications for climate warming feedbacks. Our analyses of TKL sites showing gas ebullition were complemented with geophysical surveys, providing important insight about the distribution of shallow gas in the sediments and the lake bottom manifestation of seepage (e.g., pockmarks). In Lake Q, Chirp data were limited in their capacity to image deeper sediments and did not capture the thaw bulb. The failure to capture the thaw bulb at Lake Q may in part be related to the fact that the present day lake is a remnant of an older, larger, and now-partially drained lake. These suggestions are consistent with our analyses of a dated core of sediment from the lake that shows that a wetland has been present at the site of Lake Q since approximately 12,000 thousand years ago. Chemical analyses of the core indicate that the availability of methane at the site has changed during the past and is correlated with past environmental changes (i.e. temperature and hydrology) in the Arctic. Discovery of methane seeps in Lake Teshekpuk in the northernmost part of the lake during 2009

  3. Sensitivity Studies on Productivity Performance from 3D Heterogeneous Reservoir Model Based on the L-Pad Gas Hydrate Accumulation in Prudhoe Bay Unit, North Slope Alaska

    Science.gov (United States)

    Myshakin, E. M.; Ajayi, T.; Seol, Y.; Boswell, R.

    2016-12-01

    Three-dimensional reservoir model of the "L-Pad" hydrate deposit located in the Prudhoe Bay region of the Alaska's North Slope was created including four stratigraphic units; silty shale overburden, hydrate-bearing D sand, inter-reservoir silty shale, hydrate-bearing C sand, and silty shale underburden. The model incorporates the actual geological settings, accounts for the presence of faults, reservoir dip, the hydrate-water contact in the C sand. Geostatistical porosity distributions in D and C sands conditioned to log data from 78 wells drilled in the vicinity of the Prudhoe Bay "L-pad" were developed providing vertical and lateral 3D heterogeneity in porosity and porosity-dependent hydrate saturation and intrinsic permeability. Gas production potential was estimated using a conventional vertical wellbore completion and a deviated toe-down wellbore perforated through both sand units to induce hydrate depressurization at a constant bottom-hole pressure. The results have shown the greater performance of the deviated well design over the vertical one. The scenarios involving simultaneous and sequential hydrate dissociation in sand units were explored and the effect of the underlying aquifer in the C sand was estimated. Sensitivity analysis has demonstrated that hydraulic communication with over- and underlying shale units affects production in the beginning of depressurization due to competitive water influx into producing mobile flow and could suppress efficient hydrate decomposition resulting in production lag. Another important factor greatly influencing the productivity performance is the effective permeability of hydrate-bearing sediment controlled by the relative permeability function. The results call for the necessity of thorough fundamental studies to understand multi-phase flow in hydrate-bearing sediments with different hydrate precipitation habits.

  4. Illumina-based analysis of endophytic bacterial diversity and space-time dynamics in sugar beet on the north slope of Tianshan mountain.

    Science.gov (United States)

    Shi, YingWu; Yang, Hongmei; Zhang, Tao; Sun, Jian; Lou, Kai

    2014-01-01

    Plants harbors complex and variable microbial communities. Endophytic bacteria play an important function and potential role more effectively in developing sustainable systems of crop production. To examine how endophytic bacteria in sugar beet (Beta vulgaris L.) vary across both host growth period and location, PCR-based Illumina was applied to revealed the diversity and stability of endophytic bacteria in sugar beet on the north slope of Tianshan mountain, China. A total of 60.84 M effective sequences of 16S rRNA gene V3 region were obtained from sugar beet samples. These sequences revealed huge amount of operational taxonomic units (OTUs) in sugar beet, that is, 19-121 OTUs in a beet sample, at 3 % cutoff level and sequencing depth of 30,000 sequences. We identified 13 classes from the resulting 449,585 sequences. Alphaproteobacteria were the dominant class in all sugar beets, followed by Acidobacteria, Gemmatimonadetes and Actinobacteria. A marked difference in the diversity of endophytic bacteria in sugar beet for different growth periods was evident. The greatest number of OTUs was detected during rossette formation (109 OTUs) and tuber growth (146 OTUs). Endophytic bacteria diversity was reduced during seedling growth (66 OTUs) and sucrose accumulation (95 OTUs). Forty-three OTUs were common to all four periods. There were more tags of Alphaproteobacteria and Gammaproteobacteria in Shihezi than in Changji. The dynamics of endophytic bacteria communities were influenced by plant genotype and plant growth stage. To the best of our knowledge, this study is the first application of PCR-based Illumina pyrosequencing to characterize and compare multiple sugar beet samples.

  5. RESOURCE CHARACTERIZATION AND QUANTIFICATION OF NATURAL GAS-HYDRATE AND ASSOCIATED FREE-GAS ACCUMULATIONS IN THE PRUDHOE BAY - KUPARUK RIVER AREA ON THE NORTH SLOPE OF ALASKA

    Energy Technology Data Exchange (ETDEWEB)

    Robert Hunter; Shirish Patil; Robert Casavant; Tim Collett

    2003-06-02

    Interim results are presented from the project designed to characterize, quantify, and determine the commercial feasibility of Alaska North Slope (ANS) gas-hydrate and associated free-gas resources in the Prudhoe Bay Unit (PBU), Kuparuk River Unit (KRU), and Milne Point Unit (MPU) areas. This collaborative research will provide practical input to reservoir and economic models, determine the technical feasibility of gas hydrate production, and influence future exploration and field extension of this potential ANS resource. The large magnitude of unconventional in-place gas (40-100 TCF) and conventional ANS gas commercialization evaluation creates industry-DOE alignment to assess this potential resource. This region uniquely combines known gas hydrate presence and existing production infrastructure. Many technical, economical, environmental, and safety issues require resolution before enabling gas hydrate commercial production. Gas hydrate energy resource potential has been studied for nearly three decades. However, this knowledge has not been applied to practical ANS gas hydrate resource development. ANS gas hydrate and associated free gas reservoirs are being studied to determine reservoir extent, stratigraphy, structure, continuity, quality, variability, and geophysical and petrophysical property distribution. Phase 1 will characterize reservoirs, lead to recoverable reserve and commercial potential estimates, and define procedures for gas hydrate drilling, data acquisition, completion, and production. Phases 2 and 3 will integrate well, core, log, and long-term production test data from additional wells, if justified by results from prior phases. The project could lead to future ANS gas hydrate pilot development. This project will help solve technical and economic issues to enable government and industry to make informed decisions regarding future commercialization of unconventional gas-hydrate resources.

  6. High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

    2011-01-01

    A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

  7. Paleoenvironmental interpretation of an ancient Arctic coastal plain: Integrated paleopedology and palynology from the Late Cretaceous (Maastrichtian) Prince Creek Formation, North Slope, Alaska, USA

    Science.gov (United States)

    McCarthy, P. J.; Flaig, P. P.; Fiorillo, A. R.

    2010-12-01

    The Cretaceous (Early Maastrichtian), dinosaur-bearing Prince Creek Formation, North Slope, Alaska, records high-latitude, alluvial sedimentation and soil formation on a low-lying, coastal plain during a greenhouse phase in Earth history. This study combines outcrop observations, micromorphology, geochemistry, and palynological analyses of paleosols in order to reconstruct local paleoenvironments of weakly developed, high-latitude coastal plain soils. Sediments of the Prince Creek Fm. include quartz- and chert-rich sandstone channels, and floodplains containing organic-rich siltstone and mudstone, carbonaceous shale, coal and ashfall deposits. Vertically stacked horizons of blocky-to-platy, drab-colored mudstone and siltstone with carbonaceous root-traces and mottled aggregates alternating with sandy units indicate that the development of compound and cumulative, weakly-developed soils on floodplains alternated with overbank alluviation and deposition on crevasse splay complexes on floodplains . Soil formation occurred on levees, point bars, crevasse splays and along the margins of floodplain lakes, ponds, and swamps. Soil-forming processes were interrupted by repeated deposition of sediment on top of soil profiles by flooding of nearby channels. Alluviation is evidenced by thin (coatings, and zoned peds suggest periodic waterlogging, anoxia and gleying. In contrast, Fe-oxide mottles, ferruginous and manganiferous segregations, burrows, and rare illuvial clay coatings suggest recurring oxidation and periodic drying out of some soils. Jarosite mottles and halos, and rare pyrite and gypsum found in some distal paleosols implies a marine influence at the distal margins of the coastal plain. Biota including Peridinioid dinocysts, brackish and freshwater algae, fungal hyphae, fern and moss spores, projectates, age-diagnostic Wodehouseia edmontonicola, hinterland bisaccate pollen and pollen from lowland trees, shrubs, and herbs indicate an Early Maastrichtian age for

  8. The Iġnik Sikumi Field Experiment, Alaska North Slope: Design, operations, and implications for CO2−CH4 exchange in gas hydrate reservoirs

    Science.gov (United States)

    Boswell, Ray; Schoderbek, David; Collett, Timothy S.; Ohtsuki, Satoshi; White, Mark; Anderson, Brian J.

    2017-01-01

    The Iġnik Sikumi Gas Hydrate Exchange Field Experiment was conducted by ConocoPhillips in partnership with the U.S. Department of Energy, the Japan Oil, Gas and Metals National Corporation, and the U.S. Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope during 2011 and 2012. The primary goals of the program were to (1) determine the feasibility of gas injection into hydrate-bearing sand reservoirs and (2) observe reservoir response upon subsequent flowback in order to assess the potential for CO2 exchange for CH4 in naturally occurring gas hydrate reservoirs. Initial modeling determined that no feasible means of injection of pure CO2 was likely, given the presence of free water in the reservoir. Laboratory and numerical modeling studies indicated that the injection of a mixture of CO2 and N2 offered the best potential for gas injection and exchange. The test featured the following primary operational phases: (1) injection of a gaseous phase mixture of CO2, N2, and chemical tracers; (2) flowback conducted at downhole pressures above the stability threshold for native CH4 hydrate; and (3) an extended (30-days) flowback at pressures near, and then below, the stability threshold of native CH4 hydrate. The test findings indicate that the formation of a range of mixed-gas hydrates resulted in a net exchange of CO2 for CH4 in the reservoir, although the complexity of the subsurface environment renders the nature, extent, and efficiency of the exchange reaction uncertain. The next steps in the evaluation of exchange technology should feature multiple well applications; however, such field test programs will require extensive preparatory experimental and numerical modeling studies and will likely be a secondary priority to further field testing of production through depressurization. Additional insights gained from the field program include the following: (1) gas hydrate destabilization is self-limiting, dispelling any notion of the potential for

  9. Ship Sensor Observations for Islands in the Stream 2002 - Exploration of Outer Shelf and Slope Habitats off the Coast of North Carolina - Office of Ocean Exploration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly measurements made by selected ship sensors on the R/V Seward Johnson during the 2002 "Islands in the Stream - Exploration of Outer Shelf and Slope Habitats...

  10. Combustion of mixtures of weathered Alaskan crude oils and water under external heat flux

    International Nuclear Information System (INIS)

    Walavalkar, A.Y.; Kulkarni, A.K.

    2001-01-01

    Two Alaskan oils, Milne Point crude and Alaska North Slope (ANS) crude oil were subjected to laboratory scale burn tests. These tests were conducted for weathered crude oil-water mixture layers floating on water. The oils were subjected to external radiation heat flux to determine threshold values of the heat flux required for ignition and sustained burning. It was determined that there is a threshold heat flux value for each type of mixture. Ignition and sustained combustion cannot be achieved when a layer of the mixture floating on top of the water surface is subjected to a heat flux that is lower than this threshold value. However, the mixture can be burned successfully when the external incident heat flux value is greater than or equal to the threshold value. The value of the threshold heat flux was found to be dependent on the oil type, the amount of water in the mixture, and the extent of weathering by the crude oil prior to ignition. The threshold heat flux value increased with increased amounts of water and increased level of weathering. The data for threshold heat flux correlates well with the density of crude oil at all water contents and weathering levels for all types of oil. This paper included simple charts to illustrate heat flux values for a given mixture. It was concluded that it is feasible to provide external heat flux greater than the threshold heat flux to a spill on an open body of water if an appropriately sized pool fire is started near the spill. 8 refs., 1 tab., 8 figs

  11. Slippery Slopes

    Science.gov (United States)

    2004-01-01

    The wheel tracks in this image are an artifact of the difficult terrain faced recently by NASA's Mars Exploration Rover Opportunity deep inside 'Endurance Crater.' Opportunity took the picture with its navigation camera on the rover's 205th martian day, or sol (Aug. 21, 2004). On the preceding sol, to avoid a potentially hazardous rock target, the rover team changed routes. Steep slopes and lack of traction when driving in this terrain caused the rover to experience up to 50 percent slip during parts of its traverse. Opportunity ended up more than 50 centimeters (about 20 inches) downslope from the planned final position. Another shift in objective on sol 205 had Opportunity on the move again toward safer terrain. Analysis of the final drive showed the rover's traction increasing during its latest moves.

  12. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  13. Geochemical Monitoring Of The Gas Hydrate Production By CO2/CH4 Exchange In The Ignik Sikumi Gas Hydrate Production Test Well, Alaska North Slope

    Science.gov (United States)

    Lorenson, T. D.; Collett, T. S.; Ignik Sikumi, S.

    2012-12-01

    Hydrocarbon gases, nitrogen, carbon dioxide and water were collected from production streams at the Ignik Sikumi gas hydrate production test well (TD, 791.6 m), drilled on the Alaska North Slope. The well was drilled to test the feasibility of producing methane by carbon dioxide injection that replaces methane in the solid gas hydrate. The Ignik Sikumi well penetrated a stratigraphically-bounded prospect within the Eileen gas hydrate accumulation. Regionally, the Eileen gas hydrate accumulation overlies the more deeply buried Prudhoe Bay, Milne Point, and Kuparuk River oil fields and is restricted to the up-dip portion of a series of nearshore deltaic sandstone reservoirs in the Sagavanirktok Formation. Hydrate-bearing sandstones penetrated by Ignik Sikumi well occur in three primary horizons; an upper zone, ("E" sand, 579.7 - 597.4 m) containing 17.7 meters of gas hydrate-bearing sands, a middle zone ("D" sand, 628.2 - 648.6 m) with 20.4 m of gas hydrate-bearing sands and a lower zone ("C" sand, 678.8 - 710.8 m), containing 32 m of gas hydrate-bearing sands with neutron porosity log-interpreted average gas hydrate saturations of 58, 76 and 81% respectively. A known volume mixture of 77% nitrogen and 23% carbon dioxide was injected into an isolated section of the upper part of the "C" sand to start the test. Production flow-back part of the test occurred in three stages each followed by a period of shut-in: (1) unassisted flowback; (2) pumping above native methane gas hydrate stability conditions; and (3) pumping below the native methane gas hydrate stability conditions. Methane production occurred immediately after commencing unassisted flowback. Methane concentration increased from 0 to 40% while nitrogen and carbon dioxide concentrations decreased to 48 and 12% respectively. Pumping above the hydrate stability phase boundary produced gas with a methane concentration climbing above 80% while the carbon dioxide and nitrogen concentrations fell to 2 and 18

  14. Joblessness in the Arctic: The Alaskan Paradox.

    Science.gov (United States)

    Bland, Laurel L.

    Alaska is in the paradoxical position of having more jobs available than people, and at the same time maintaining one of the highest unemployment rates in the nation. This report discusses the nature and skills of the unemployed and underemployed, and presents tables of demographic information. While a fair percentage of Alaskan native youth…

  15. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

  16. Holocene Paleoceanographic Environments at the Chukchi-Alaskan Margin: Implications for Future Changes

    Science.gov (United States)

    Polyak, L.; Nam, S. I.; Dipre, G.; Kim, S. Y.; Ortiz, J. D.; Darby, D. A.

    2017-12-01

    The impacts of the North Pacific oceanic and atmospheric system on the Arctic Ocean result in accelerated sea-ice retreat and related changes in hydrography and biota in the western Arctic. Paleoclimatic records from the Pacific sector of the Arctic are key for understanding the long-term history of these interactions. As opposed to stratigraphically long but strongly compressed sediment cores recovered from the deep Arctic Ocean, sediment depocenters on the Chukchi-Alaskan margin yield continuous, medium to high resolution records formed since the last deglaciation. While early Holocene conditions were non-analogous to modern environments due to the effects of prolonged deglaciation and insufficiently high sea levels, mid to late Holocene sediments are more relevant for recent and modern climate variability. Notably, a large depocenter at the Alaskan margin has sedimentation rates estimated as high as a few millimeters per year, thus providing a decadal to near-annual resolution. This high accumulation can be explained by sediment delivery via the Alaskan Coastal Current originating from the Bering Sea and supposedly controlled by the Aleutian Low pressure center. Preliminary results from sediment cores recovering the last several centuries, along with a comparison with other paleoclimatic proxy records from the Arctic-North Pacific region, indicate a persistent role of the Aleutian Low in the Bering Strait inflow and attendant deposition. More proxy studies are underway to reconstruct the history of this circulation system and its relationship with sea ice extent. The expected results will improve our understanding of natural variability in oceanic and atmospheric conditions at the Chukchi-Alaskan margin, a critical area for modulating the Arctic climate change.

  17. Aerobic Methane Oxidation in Alaskan Lakes Along a Latitudinal Transect

    Science.gov (United States)

    Martinez-Cruz, K. C.; Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Anthony, P.; Thalasso, F.

    2013-12-01

    Karla Martinez-Cruz* **, Armando Sepulveda-Jauregui*, Katey M. Walter Anthony*, Peter Anthony*, and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Methane (CH4) is the third most important greenhouse gas in the atmosphere, after carbon dioxide and water vapor. Boreal lakes play an important role in the current global warming by contributing as much as 6% of global atmospheric CH4 sources annually. On the other hand, aerobic methane oxidation (methanotrophy) in lake water is a fundamental process in global methane cycling that reduces the amount of CH4 emissions to the atmosphere. Several environmental factors affect aerobic methane oxidation in the water column both directly and indirectly, including concentration of CH4 and O2, temperature and carbon budgets of lakes. We analyzed the potential of aerobic methane oxidation (PMO) rates in incubations of water collected from 30 Alaskan lakes along a north-south transect during winter and summer 2011. Our findings showed an effect of CH4 and O2 concentrations, temperature and yedoma thawing permafrost on PMO activity in the lake water. The highest PMO rates were observed in summer by lakes situated on thawing yedoma permafrost, most of them located in the interior of Alaska. We also estimated that 60-80% of all CH4 produced in Alaskan lakes could be taken up by methanotrophs in the lake water column, showing the significant influence of aerobic methane oxidation of boreal lakes to the global CH4 budget.

  18. Mechanisms influencing changes in lake area in Alaskan boreal forest

    Science.gov (United States)

    Roach, Jennifer K.; Griffith, Brad; Verbyla, David; Jones, Jeremy B.

    2011-01-01

    During the past ∼50 years, the number and area of lakes have declined in several regions in boreal forests. However, there has been substantial finer-scale heterogeneity; some lakes decreased in area, some showed no trend, and others increased. The objective of this study was to identify the primary mechanisms underlying heterogeneous trends in closed-basin lake area. Eight lake characteristics (δ18O, electrical conductivity, surface : volume index, bank slope, floating mat width, peat depth, thaw depth at shoreline, and thaw depth at the forest boundary) were compared for 15 lake pairs in Alaskan boreal forest where one lake had decreased in area since ∼1950, and the other had not. Mean differences in characteristics between paired lakes were used to identify the most likely of nine mechanistic scenarios that combined three potential mechanisms for decreasing lake area (talik drainage, surface water evaporation, and terrestrialization) with three potential mechanisms for nondecreasing lake area (subpermafrost groundwater recharge through an open talik, stable permafrost, and thermokarst). A priori expectations of the direction of mean differences between decreasing and nondecreasing paired lakes were generated for each scenario. Decreasing lakes had significantly greater electrical conductivity, greater surface : volume indices, shallower bank slopes, wider floating mats, greater peat depths, and shallower thaw depths at the forest boundary. These results indicated that the most likely scenario was terrestrialization as the mechanism for lake area reduction combined with thermokarst as the mechanism for nondecreasing lake area. Terrestrialization and thermokarst may have been enhanced by recent warming which has both accelerated permafrost thawing and lengthened the growing season, thereby increasing plant growth, floating mat encroachment, transpiration rates, and the accumulation of organic matter in lake basins. The transition to peatlands associated

  19. Keeping Alaskan Tradition Alive: Building Relationships in the Curriculum

    Science.gov (United States)

    Hughes, Eileen; Forbes, Sue

    2005-01-01

    This article reviews varied types of relationships that were formed when a kindergarten class embarked on a study of the Native Alaskan art of carving. The public school kindergarten classroom, located in Anchorage, Alaska, drew from a community with a high population of Hispanic, African American, and Native Alaskan families with different…

  20. 7 CFR 1780.49 - Rural or Native Alaskan villages.

    Science.gov (United States)

    2010-01-01

    ..., processed, and serviced in accordance with this subpart. (b) Definitions—(1) Dire sanitation condition. For the purpose of this section a dire sanitation condition exists where: (i) Recurring instances of a...) Rural or Native Alaskan village. A rural or Native Alaskan community which meets the definition of a...

  1. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Ali Kadaster; Bill Liddell; Tommy Thompson; Thomas Williams; Michael Niedermayr

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and implemented for determining physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. Final efforts of the project are to correlate geology, geophysics, logs, and drilling and

  2. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Steve Runyon; Mike Globe; Kent Newsham; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling

  3. Evaluation of TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis)'s predictive skill for hurricane-triggered landslides: A case study in Macon County, North Carolina

    Science.gov (United States)

    Liao, Z.; Hong, Y.; Kirschbaum, D.; Adler, R.F.; Gourley, J.J.; Wooten, R.

    2011-01-01

    The key to advancing the predictability of rainfall-triggered landslides is to use physically based slope-stability models that simulate the transient dynamical response of the subsurface moisture to spatiotemporal variability of rainfall in complex terrains. TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis) is a USGS landslide prediction model, coded in Fortran, that accounts for the influences of hydrology, topography, and soil physics on slope stability. In this study, we quantitatively evaluate the spatiotemporal predictability of a Matlab version of TRIGRS (MaTRIGRS) in the Blue Ridge Mountains of Macon County, North Carolina where Hurricanes Ivan triggered widespread landslides in the 2004 hurricane season. High resolution digital elevation model (DEM) data (6-m LiDAR), USGS STATSGO soil database, and NOAA/NWS combined radar and gauge precipitation are used as inputs to the model. A local landslide inventory database from North Carolina Geological Survey is used to evaluate the MaTRIGRS' predictive skill for the landslide locations and timing, identifying predictions within a 120-m radius of observed landslides over the 30-h period of Hurricane Ivan's passage in September 2004. Results show that within a radius of 24 m from the landslide location about 67% of the landslide, observations could be successfully predicted but with a high false alarm ratio (90%). If the radius of observation is extended to 120 m, 98% of the landslides are detected with an 18% false alarm ratio. This study shows that MaTRIGRS demonstrates acceptable spatiotemporal predictive skill for landslide occurrences within a 120-m radius in space and a hurricane-event-duration (h) in time, offering the potential to serve as a landslide warning system in areas where accurate rainfall forecasts and detailed field data are available. The validation can be further improved with additional landslide information including the exact time of failure for each

  4. UV-continuum slopes of >4000 z ∼ 4-8 galaxies from the HUDF/XDF, HUDF09, ERS, CANDELS-SOUTH, and CANDELS-NORTH fields

    Energy Technology Data Exchange (ETDEWEB)

    Bouwens, R. J.; Labbé, I.; Franx, M.; Smit, R. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Illingworth, G. D.; Oesch, P. A.; Gonzalez, V.; Magee, D. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Van Dokkum, P. G. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Trenti, M. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2014-10-01

    We measure the UV-continuum slope β for over 4000 high-redshift galaxies over a wide range of redshifts z ∼ 4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new β results reach very faint levels at z ∼ 4 (–15.5 mag: 0.006 L{sub z=3}{sup ∗}), z ∼ 5 (–16.5 mag: 0.014 L{sub z=3}{sup ∗}), and z ∼ 6 and z ∼ 7 (–17 mag: 0.025 L{sub z=3}{sup ∗}). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring β that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in β. We find that after correcting for the systematic errors (typically Δβ ∼ 0.1-0.2) all β results at z ∼ 7 from different groups are in excellent agreement. The mean β we measure for faint (–18 mag: 0.1 L{sub z=3}{sup ∗}) z ∼ 4, z ∼ 5, z ∼ 6, and z ∼ 7 galaxies is –2.03 ± 0.03 ± 0.06 (random and systematic errors), –2.14 ± 0.06 ± 0.06, –2.24 ± 0.11 ± 0.08, and –2.30 ± 0.18 ± 0.13, respectively. Our new β values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer β's at lower luminosities is confirmed, as is the evolution to bluer β's at high redshifts. β appears to show only a mild luminosity dependence faintward of M {sub UV,AB} ∼ –19 mag, suggesting that the mean β asymptotes to ∼–2.2 to –2.4 for faint z ≥ 4 galaxies. At z ∼ 7, the observed β's suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations.

  5. Quantifying the impact of anthropogenic pollution on cloud properties derived from ground based remote sensors at the North Slope of Alaska

    Science.gov (United States)

    Maahn, M.; Acquistapace, C.; de Boer, G.; Cox, C.; Feingold, G.; Marke, T.; Williams, C. R.

    2017-12-01

    When acting as cloud condensation nuclei (CCN) or ice nucleating particles (INPs), aerosols have a strong potential to influence cloud properties. In particular, they can impact the number, size, and phase of cloud particles and potentially cloud lifetime through aerosol indirect and semi-direct effects. In polar regions, these effects are of great importance for the radiation budget due to the shortwave albedo and longwave emissivity of mixed-phase clouds. The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program operates two super sites equipped with state of the art ground-based remote sensing instruments in northern Alaska. The sites are both coastal and are highly correlated with respect to large scale synoptic patterns. While the site at Utqiaġvik (formerly known as Barrow) generally represents a relatively pristine Arctic environment lacking significant anthropogenic sources, the site at Oliktok Point, approximately 250 km to the east, is surrounded by the Prudhoe Bay Oil Field, which is the largest oil field in North America. Based on aircraft measurement, the authors recently showed that differences in the properties of liquid clouds properties between the sites can be attributed to local emissions associated with the industrial activities in the Prudhoe Bay region (Maahn et al. 2017, ACPD). However, aircraft measurements do not provide a representative sample of cloud properties due to temporal limitations in the amount of data. In order to investigate how frequently and to what extent liquid cloud properties and processes are modified, we use ground based remote sensing observations such as e.g., cloud radar, Doppler lidar, and microwave radiometer obtained continuously at the two sites. In this way, we are able to quantify inter-site differences with respect to cloud drizzle production, liquid water path, frequency of cloud occurrence, and cloud radiative properties. Turbulence and the coupling of clouds to the boundary layer is

  6. Recent increased warming of the Alaskan marine Arctic due to midlatitude linkages

    Science.gov (United States)

    Overland, James E.; Wang, Muyin; Ballinger, Thomas J.

    2018-01-01

    Alaskan Arctic waters have participated in hemispheric-wide Arctic warming over the last two decades at over two times the rate of global warming. During 2008-13, this relative warming occurred only north of the Bering Strait and the atmospheric Arctic front that forms a north-south thermal barrier. This front separates the southeastern Bering Sea temperatures from Arctic air masses. Model projections show that future temperatures in the Chukchi and Beaufort seas continue to warm at a rate greater than the global rate, reaching a change of +4°C by 2040 relative to the 1981-2010 mean. Offshore at 74°N, climate models project the open water duration season to increase from a current average of three months to five months by 2040. These rates are occasionally enhanced by midlatitude connections. Beginning in August 2014, additional Arctic warming was initiated due to increased SST anomalies in the North Pacific and associated shifts to southerly winds over Alaska, especially in winter 2015-16. While global warming and equatorial teleconnections are implicated in North Pacific SSTs, the ending of the 2014-16 North Pacific warm event demonstrates the importance of internal, chaotic atmospheric natural variability on weather conditions in any given year. Impacts from global warming on Alaskan Arctic temperature increases and sea-ice and snow loss, with occasional North Pacific support, are projected to continue to propagate through the marine ecosystem in the foreseeable future. The ecological and societal consequences of such changes show a radical departure from the current Arctic environment.

  7. Currents, attenuation, temperature, conductivity, and pressure in the North Atlantic Ocean on the New England Continental Slope from the RV OCEANUS from November 10th, 1982 through November 18th, 1984 (NODC Accession 0066097)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A study of currents on the Continental Slope designed to describe the currents and to investigate the transport of sediment from the shelf to the slope. This work...

  8. Using smooth sheets to describe groundfish habitat in Alaskan waters, with specific application to two flatfishes

    Science.gov (United States)

    Zimmermann, Mark; Reid, Jane A.; Golden, Nadine

    2016-01-01

    In this analysis we demonstrate how preferred fish habitat can be predicted and mapped for juveniles of two Alaskan groundfish species – Pacific halibut (Hippoglossus stenolepis) and flathead sole (Hippoglossoides elassodon) – at five sites (Kiliuda Bay, Izhut Bay, Port Dick, Aialik Bay, and the Barren Islands) in the central Gulf of Alaska. The method involves using geographic information system (GIS) software to extract appropriate information from National Ocean Service (NOS) smooth sheets that are available from NGDC (the National Geophysical Data Center). These smooth sheets are highly detailed charts that include more soundings, substrates, shoreline and feature information than the more commonly-known navigational charts. By bringing the information from smooth sheets into a GIS, a variety of surfaces, such as depth, slope, rugosity and mean grain size were interpolated into raster surfaces. Other measurements such as site openness, shoreline length, proportion of bay that is near shore, areas of rocky reefs and kelp beds, water volumes, surface areas and vertical cross-sections were also made in order to quantify differences between the study sites. Proper GIS processing also allows linking the smooth sheets to other data sets, such as orthographic satellite photographs, topographic maps and precipitation estimates from which watersheds and runoff can be derived. This same methodology can be applied to larger areas, taking advantage of these free data sets to describe predicted groundfish essential fish habitat (EFH) in Alaskan waters.

  9. Characterization of Alaskan HMA mixtures with the simple performance tester.

    Science.gov (United States)

    2014-05-01

    Material characterization provides basic and essential information for pavement design and the evaluation of hot mix asphalt (HMA). : This study focused on the accurate characterization of an Alaskan HMA mixture using an asphalt mixture performance t...

  10. Salt water-acclimated pink salmon fry (Oncorhynchus gorbuscha) develop stress-related visceral lesions after 10-day exposure to sublethal concentrations of the water-soluble fraction of North Slope crude oil.

    Science.gov (United States)

    Brand, D G; Fink, R; Bengeyfield, W; Birtwell, I K; McAllister, C D

    2001-01-01

    Pink salmon fry. Oncorhynchus gorbuscha, after a 10-day exposure to one of two sublethal concentrations (25-54 microg x L(-1) or 178-348 microg x L(-1)) of the water-soluble fractions from Alaska North Slope crude oil, possessed morphologic and stress induced lesions in their hepatic, head kidney and gill tissues. Analysis of livers from oil-exposed fry revealed a variety of hepatocellular changes, including steatosis, nuclear pleomorphism. megalocytosis and necrosis. Epithelial proliferation of the bile ducts also occurred. An increase in the head kidney's interrenal cell nuclear diameter, a biomarker for stress responses, was correlated with hydrocarbon exposure. Gill abnormalities such as eqithelial lifting. fusion, mucous cell hyperplasia and vascular constriction were found in all test groups, but were more severe in fry given the high water soluble fraction of crude oil. The study demonstrated that sublethal exposure to the water-soluble fraction of crude oil results in multiple microscopic lesions (in several viscera) that are consistent with a pronounced response to environmental stress.

  11. Regional comparison of tundra carbon budget response over the Alaska North Slope to varying environmental conditions as informed by in situ and flux tower measurements, remote sensing and biophysical modeling

    Science.gov (United States)

    Shirley, S.; Watts, J. D.; Kimball, J. S.; Zhang, Z.; Poulter, B.; Klene, A. E.; Jones, L. A.; Kim, Y.; Oechel, W. C.; Zona, D.; Euskirchen, E. S.

    2017-12-01

    A warming Arctic climate is contributing to shifts in landscape moisture and temperature regimes, a shortening of the non-frozen season, and increases in the depth of annual active layer. The changing environmental conditions make it difficult to determine whether tundra ecosystems are a carbon sink or source. At present, eddy covariance flux towers and biophysical measurements within the tower footprint provide the most direct assessment of change to the tundra carbon balance. However, these measurements have a limited spatial footprint and exist over relatively short timescales. Thus, terrestrial ecosystem models are needed to provide an improved understanding of how changes in landscape environmental conditions impact regional carbon fluxes. This study examines the primary drivers thought to affect the magnitude and variability of tundra-atmosphere CO2 and CH4 fluxes over the Alaska North Slope. Also investigated is the ability of biophysical models to capture seasonal flux characteristics over the 9 tundra tower sites examined. First, we apply a regression tree approach to ascertain which remotely sensed environmental variables best explain observed variability in the tower fluxes. Next, we compare flux estimates obtained from multiple process models including Terrestrial Carbon Flux (TCF) and the Lund-Potsdam-Jena Wald Schnee und Landschaft (LPJ-wsl), and Soil Moisture Active Passive Level 4 Carbon (SMAP L4_C) products. Our results indicate that out of 7 variables examined vegetation greenness, temperature, and moisture are more significant predictors of carbon flux magnitude over the tundra tower sites. This study found that satellite data-driven models, due to the ability of remote sensing instruments to capture the physical principles and processes driving tundra carbon flux, are more effective at estimating the magnitude and spatiotemporal variability of CO2 and CH4 fluxes in northern high latitude ecosystems.

  12. Microphysical Properties of Alaskan Volcanic Ash

    Science.gov (United States)

    Puthukkudy, A.; Espinosa, R.; Rocha Lima, A.; Remer, L.; Colarco, P. R.; Whelley, P.; Krotkov, N. A.; Young, K.; Dubovik, O.; Wallace, K.; Martins, J. V.

    2017-12-01

    Volcanic ash has the potential to cause a variety of severe problems for human health and the environment. Therefore, effective monitoring of the dispersion and fallout from volcanic ash clouds and characterization of the aerosol particle properties are essential. One way to acquire information from volcanic clouds is through satellite remote sensing: such images have greater coverage than ground-based observations and can present a "big picture" perspective. A challenge of remote sensing is that assumptions of certain properties of the target are often a pre-requisite for making accurate and quantitative retrievals. For example, detailed information about size distribution, sphericity, and optical properties of the constituent matter is needed or must be assumed. The same kind of information is also needed for atmospheric transport models to properly simulate the dispersion and fallout of volcanic ash. Presented here is a laboratory method to determine the microphysical and optical properties of volcanic ash samples collected from two Alaskan volcanoes with markedly different compositions. Our method uses a Polarized Imaging Nephelometer (PI-Neph) and a system that re-suspends the particles in an air flow. The PI-Neph measures angular light scattering and polarization of the re-suspended particles from 3o to 175o in scattering angle, with an angular resolution of 1o . Primary measurements include phase function and polarized phase function at three wavelengths (445nm, 532nm, and 661nm). Size distribution, sphericity, and complex refractive index are retrieved indirectly from the PI-Neph measurements using the GRASP (Generalized Retrieval of Aerosol and Surface Properties) inversion algorithm. We report the results of this method applied to samples from the Mt. Okmok (2008) and Mt. Katmai (1912) volcanic eruptions. To our knowledge, this is the first time direct measurements of phase matrix elements of ash from Mt. Okmok and Mt. Katmai have been reported. Retrieved

  13. Preliminary Slope Stability Study Using Slope/ W

    International Nuclear Information System (INIS)

    Nazran Harun; Mohd Abd Wahab Yusof; Kamarudin Samuding; Mohd Muzamil Mohd Hashim; Nurul Fairuz Diyana Bahrudin

    2014-01-01

    Analyzing the stability of earth structures is the oldest type of numerical analysis in geotechnical engineering. Limit equilibrium types of analyses for assessing the stability of earth slopes have been in use in geotechnical engineering for many decades. Modern limit equilibrium software is making it possible to handle ever-increasing complexity within an analysis. It is being considered as the potential method in dealing with complex stratigraphy, highly irregular pore-water pressure conditions, various linear and nonlinear shear strength models and almost any kind of slip surface shape. It allows rapid decision making by providing an early indication of the potential suitability of sites based on slope stability analysis. Hence, a preliminary slope stability study has been developed to improve the capacity of Malaysian Nuclear Agency (Nuclear Malaysia) in assessing potential sites for Borehole Disposal for Disused Sealed Radioactive Sources. The results showed that geometry of cross section A-A ' , B-B ' , C-C ' and D-D ' achieved the factor of safety not less than 1.4 and these are deemed acceptable. (author)

  14. Rock Slope Design Criteria

    Science.gov (United States)

    2010-06-01

    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary : rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, : and siltstones ...

  15. Dark Slope Streaks

    Science.gov (United States)

    2004-01-01

    13 March 2004 Martian slope streaks occur in the regions most heavily mantled by fine, dry dust, particularly Tharsis, Arabia, and the knobby areas between Amazonis and Cerberus. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some examples of dark slope streaks off of buttes, mesas, and massifs in a dust-mantled crater in central Arabia Terra. New slope streaks form from time to time in the modern martian environment; the streaks in this image probably formed within the past decade. To create them, dust slid or avalanched down the slopes in an almost liquid-like manner. The image is located near 6.8oN, 321.7oW. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  16. Unstable slope management program.

    Science.gov (United States)

    2009-08-01

    This Rapid Response Project gathered information on existing unstable slope management programs, with a : focus on asset management practices in the United States and overseas. On the basis of this study, the research : team summarized and recommende...

  17. Rock slope design guide.

    Science.gov (United States)

    2011-04-01

    This Manual is intended to provide guidance for the design of rock cut slopes, rockfall catchment, and : rockfall controls. Recommendations presented in this manual are based on research presented in Shakoor : and Admassu (2010) entitled Rock Slop...

  18. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  19. Late Pleistocene shallow water sand transported to the slope at IODP Sites U1484 and U1485 off the north coast of Papua New Guinea: how, when and why?

    Science.gov (United States)

    Mountain, G. S.; Browning, J. V.; Bova, S. C.

    2017-12-01

    IODP Exp 363 drilled two sites on a gently seaward-dipping terrace 18 and 21 km north of Papua New Guinea, enabling the study of mechanisms that bring shallow water sediment to the deep sea. We expect past changes in sea level and precipitation / fluvial run-off dominated this record, but additional processes may have been important. We examined Hole U1484B (1031 m water depth; 223 m drilled; 99.8% recovered) and detected 339 sharp-based sand layers 0.5 cm or more thick. In contrast to the background hemipelagic nanno-bearing silty clay, sand layers are graded or massive turbidites containing detrital grains, shallow-water benthic foraminifera, shell fragments and/or wood. δ18O values of Globigerinoides ruber tied to the isotopic curve of Lisiecki and Raymo (2004) show the densest concentration of sand layers in the last 310 ka occurred during the cooling trend of MIS stage 6. Stage 2 contains significantly fewer discrete sand beds, even during the coldest part of the LGM. Other times of glacial intensification show a similarly modest correlation to peak sand deposition. Sand layers strongly correlate with high values of magnetic susceptibility (MS) measured on unsplit cores, and when mapped to the MIS time scale, MS increases match times of ice growth / falling sea level more consistently than does the density of sand layers. We attribute this to reworking of discrete sand layers by bioturbation, indicating the need for caution tying the absence of sharp-based sands to times of transgression or low precipitation / fluvial run-off. Packages of especially thick and closely-spaced sharp-based sands match seismic reflections at Site U1484. Tracing these reflections throughout the grid of hi-res MCS site survey profiles reveals the areal distribution and transport path of sand as well as a direct tie to similar sharp-based sands in the more distal Hole U1485A (1145 m water depth; 301 m drilled; 103.8% recovered.) The distribution of sands through time might be

  20. Change in the Nd isotopic composition of the bottom water and detrital sediments on the Bering Slope over the last 500 kyrs with implications for the formation of the North Pacific Intermediate Water

    Science.gov (United States)

    Jang, K.; Huh, Y.; Han, Y.

    2015-12-01

    The Bering Sea is a potential location for the formation of the North Pacific Intermediate/Deep Water (NPIW/NPDW) and may play an important role in the global heat distribution. We reconstructed the neodymium isotopic ratio (ɛNd) of authigenic Fe-Mn oxide coatings and detrital sediments on the Bering Slope (IODP Expedition 323 site U1345; water depth 1008 m) over the last 500 kyrs. The ɛNd is a quasi-conservative water mass tracer. We compared three different leaching techniques to assure that authigenic signals are captured without contamination from terrigenous sources: (1) leaching (3 hours) with 0.02 M hydroxylamine hydrochloride (HH) in 25% buffered acetic acid after decarbonation; sediment/solution (v/v) > 10, (2) leaching (1 hour) with 0.02 M HH in 25% buffered acetic acid without decarbonation; sediment/solution ~ 1, and (3) leaching (1 hour) with 0.005 M HH in 1.5% buffered acetic acid-0.003 M Na-EDTA without decarbonation; sediment/solution > 40. The low Al concentrations and less radiogenic ɛNdvalues indicated that method (2) is the most appropriate leaching process. The average ɛNd of the authigenic fraction over the last 500 kyrs is -3.3 ± 0.9 (1σ, n=38), with large temporal fluctuations. The ɛNd of authigenic and detrital fractions are well correlated (r2 ~ 0.66), suggesting that the bottom water composition in the Bering Sea was governed by terrigenous inflow from surrounding areas. Radiogenic ɛNd peaks (up to -1.9) seem to be influenced by radiogenic water inflow from the the Kamchatka or Aluetian arcs. The high bulk density and low b* values imply higher terrigenous versus biological contribution and enhanced sea ice formation. Subsequent brine formation would have triggered sinking of radiogenic surface water, forming the NPIW. On the other hand, non-radiogenic ɛNd troughs (down to -5.3) are observed at times of low bulk density and high b* values. We presume higher biological productivity which is supported by the high opal content at

  1. Radon in homes: The Alaskan experience

    International Nuclear Information System (INIS)

    Seifert, R.D.

    1990-01-01

    For the past four years, since radon was first found to be a concern in Alaska in 1986, the interest and awareness of radon as a special housing and health concern has continued to grow. This paper will discuss the features of a house in Alaska which would characterize it as at risk for radon, and also those efforts at mitigation which have been most effective in reducing radon under Alaskan conditions. Clearly radon must be able to enter a home in order to be a problem. Riefenstuhl and Kline (personal communication, 1988) have analyzed the conditions for radon transport from soils to home interiors very lucidly through the following scheme: four factors must exist in a house locale for it to be a radon at risk house. Two of the factors are geological in nature: (1) there must be adequate uranium and therefore ample radon to provide a source for transport; (2) there must be enough permeability in the soil to allow rapid soil gas movement to carry radon from its origin to the interior of the home within two half-lives of time (six days) or so. The other two factors are determined by the structure of the house itself and the way in which it is operated: (3) the house must have soil contact and imperfections, holes, cracks, intentional perforations which allow movement of soil gas with radon through the envelope of the basement or crawlspace; (4) there must be a lower pressure inside the house than in the soil so that soil gas flows into the house. All four of these characteristics are required to have radon be a problem. The absence of any single characteristic will eliminate radon (in general). This presents a series of options for mitigation of radon then, since elimination of any of the four characteristics will mitigate radon

  2. Seismic array processing and computational infrastructure for improved monitoring of Alaskan and Aleutian seismicity and volcanoes

    Science.gov (United States)

    Lindquist, Kent Gordon

    We constructed a near-real-time system, called Iceworm, to automate seismic data collection, processing, storage, and distribution at the Alaska Earthquake Information Center (AEIC). Phase-picking, phase association, and interprocess communication components come from Earthworm (U.S. Geological Survey). A new generic, internal format for digital data supports unified handling of data from diverse sources. A new infrastructure for applying processing algorithms to near-real-time data streams supports automated information extraction from seismic wavefields. Integration of Datascope (U. of Colorado) provides relational database management of all automated measurements, parametric information for located hypocenters, and waveform data from Iceworm. Data from 1997 yield 329 earthquakes located by both Iceworm and the AEIC. Of these, 203 have location residuals under 22 km, sufficient for hazard response. Regionalized inversions for local magnitude in Alaska yield Msb{L} calibration curves (logAsb0) that differ from the Californian Richter magnitude. The new curve is 0.2\\ Msb{L} units more attenuative than the Californian curve at 400 km for earthquakes north of the Denali fault. South of the fault, and for a region north of Cook Inlet, the difference is 0.4\\ Msb{L}. A curve for deep events differs by 0.6\\ Msb{L} at 650 km. We expand geographic coverage of Alaskan regional seismic monitoring to the Aleutians, the Bering Sea, and the entire Arctic by initiating the processing of four short-period, Alaskan seismic arrays. To show the array stations' sensitivity, we detect and locate two microearthquakes that were missed by the AEIC. An empirical study of the location sensitivity of the arrays predicts improvements over the Alaskan regional network that are shown as map-view contour plots. We verify these predictions by detecting an Msb{L} 3.2 event near Unimak Island with one array. The detection and location of four representative earthquakes illustrates the expansion

  3. Standard Implications: Alaskans Reflect on a Movement To Change Teaching.

    Science.gov (United States)

    Calkins, Annie, Ed.; Christian, Scott, Ed.

    In this anthology, rural Alaskan English teachers in the Bread Loaf Rural Teacher Network describe their experiences implementing new state education standards while continuing their commitment to learner-centered and place-based practice. The book presents narratives about teaching grounded in knowledge and understanding of students and…

  4. Slope earthquake stability

    CERN Document Server

    Changwei, Yang; Jing, Lian; Wenying, Yu; Jianjing, Zhang

    2017-01-01

    This book begins with the dynamic characteristics of the covering layerbedrock type slope, containing monitoring data of the seismic array, shaking table tests, numerical analysis and theoretical derivation. Then it focuses on the landslide mechanism and assessment method. It also proposes a model that assessing the hazard area based on the field investigations. Many questions, exercises and solutions are given. Researchers and engineers in the field of Geotechnical Engineering and Anti-seismic Engineering can benefit from it.

  5. Lithospheric Structure across the Alaskan Cordillera from Surface Waves and Receiver Functions

    Science.gov (United States)

    Ward, K. M.; Lin, F. C.

    2017-12-01

    The long awaited Transportable Array (TA) deployment in Alaska and western Canada is nearing its final deployment stage. With only one more deployment season, most of the TA station locations have been occupied and begun providing data. These TA stations combined with upgraded existing locations have provided enough high-quality data to begin investigating the crustal and upper mantle structure across the entire Alaskan Cordillera. From a tectonic standpoint, many interesting questions remain unanswered. For example, how does the transition from oceanic-oceanic subduction to continental-oceanic normal subduction to continental-oceanic "flat-slab" subduction to strike-slip conservative plate motion affect the deformation/uplift of the overriding plate and mantle geodynamic characteristics? How does the long and completed terrene accretion process partition stress/strain in the crust? On more local scales, are there any significant mid-crustal magmatic systems as observed in other sections of the American Cordillera, and if so, what is there role in uplift and crustal deformation? Our approach to investigating these questions is though surface wave imaging from ambient noise and earthquake generated sources along with Rayleigh wave ellipticity paired with Ps receiver functions. Our preliminary tomography results agree with previous studies but expand the spatial coverage showing additional detail. Our ellipticity results show a heterogeneous but spatially consistent anisotropic shallow crust. Although the complete TA data set has not yet been collected, we have jointly inverted surface waves with receiver functions for a 3-D shear-wave velocity model across the entire Alaskan Cordillera. Key features of our velocity model include a high-velocity feature in the upper mantle associated with the subducting Pacific plate that extends north of the seismicity used to contour the geometry of the slab and mid-crustal low-velocity zones associated with the active volcanics in

  6. The Q-Slope Method for Rock Slope Engineering

    Science.gov (United States)

    Bar, Neil; Barton, Nick

    2017-12-01

    Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in opencast mines, Q-slope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction. Through case studies across Asia, Australia, Central America, and Europe, a simple correlation between Q-slope and long-term stable slopes was established. Q-slope is designed such that it suggests stable, maintenance-free bench-face slope angles of, for instance, 40°-45°, 60°-65°, and 80°-85° with respective Q-slope values of approximately 0.1, 1.0, and 10. Q-slope was developed by supplementing the Q-system which has been extensively used for characterizing rock exposures, drill-core, and tunnels under construction for the last 40 years. The Q' parameters (RQD, J n, J a, and J r) remain unchanged in Q-slope. However, a new method for applying J r/ J a ratios to both sides of potential wedges is used, with relative orientation weightings for each side. The term J w, which is now termed J wice, takes into account long-term exposure to various climatic and environmental conditions such as intense erosive rainfall and ice-wedging effects. Slope-relevant SRF categories for slope surface conditions, stress-strength ratios, and major discontinuities such as faults, weakness zones, or joint swarms have also been incorporated. This paper discusses the applicability of the Q-slope method to slopes ranging from less than 5 m to more than 250 m in height in both civil and mining engineering projects.

  7. Revegetation of Alaskan coal mine spoils. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, W W; Mitchell, G A; McKendrick, J D

    1980-05-23

    Activities initiated after the start of the revegetation project on Alaskan coal mine spoils on September 1, 1979 have consisted mainly of some fall plantings (dormant seedings) and soil and coal spoil samplings and analyses. Because of the late summer start for the project, only a limited amount of field work could be initiated in plant material studies. This consisted of a fall planting at the Usibelli mine site at Healy in interior Alaska. The planting was intended to test the efficacy of seeding in the frost period following the growing season, requiring the seed to remain dormant over winter and to germinate when conditions become favorable in late spring. It also was intended as a comparison of a number of different grasses. Thirty entries were seeded in three replications. Fifteen species of grasses and a clover were included in the trial. The site provided for the trial was on overburden material along a streambed. Among the entries were eight cultivars of introduced grasses, five cultivars of native Alaskan germplasm, one introduced clover cultivar, and sixteen experimental grasses mainly of Alaskan origin.

  8. A Different Pitch to Slope

    Science.gov (United States)

    Wolbert, William

    2017-01-01

    The query "When are we ever going to use this?" is easily answered when discussing the slope of a line. The pitch of a roof, the grade of a road, and stair stringers are three applications of slope that are used extensively. The concept of slope, which is introduced fairly early in the mathematics curriculum has hands-on applications…

  9. Two Oil Types on the North Slope of Alaska. Implications for Future Exploration Les deux types d'huile du versant septentrional de l'Alaska. Implications pour l'exploration future

    Directory of Open Access Journals (Sweden)

    Magoon L. B.

    2006-10-01

    Full Text Available Forty oil samples from across the North Slope of Alaska have been analyzed by the US Bureau of Mines and the Us Geological Survey. Results of these analyses suggest two separate genetic oil types. The first type, the Simpson-Umiat oil type, occurs in reservoir rocks of Cretaceous and Quaternary age and includes oils from seeps in the Skull Cliff, Cape Simpson, Manning Point, and Ungoon Point areas; the Wolf Creek test well 3, and the Umiat oil field. These are higher gravity, low-sulfur oils with no, or slight, odd-numbered n-alkane predominance and pristane to phytane ratios greater than 1. 5. The second type, the Barrow-Prudhoe oil type, occurs in reservoir rocks of Carboniferous to Cretataceous age and includes ails from South Barrow gas field, Prudhoe Bay oil field, and the Fish Creek test well 1. Physical properties of Barrow-Prudhoe oils are variable, but in general the oils are medium-gravity, high-sulfur oils with a slight even-numbered n-alkane predominance and pristane to phytane ratio of less thon 1. 5. The two types are believed to originated from different source rocks; the Barrow-Prudhoe type may have originated from a carbonate or other iron-deficient source rock, and the Simpson-Umiat type from asiliciclastic source rock. Occurrences of fine two oil types, when outlined on a map, indicate atleast two exploration fairways. The fairway for the Barrow-Prudhoe type is along the Barrow arch, and the fairway, for the Simpson-Umiat type is the area of the best reservoir development for the Nanushuk Group. Quarante échantillons d'huile prélevés à travers le versant septentrional de l'Alaska ont été analysés par l'US Bureau of Mines et l'US Geological Survey. Les résultats de ces analyses suggèrent deux types séparés d'huile. Le premier, le type d'huile Simpson-Umiat, se trouve dans des roches magasins du Crétacé au Quaternaire et comprend des huiles des suintements des régions de la falaise Skull, du cap Simpson, de Point

  10. On Front Slope Stability of Berm Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    2013-01-01

    The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison with the r......The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison...... with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model...... test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height...

  11. [Alaskan commodities irradiation project: An options analysis study

    International Nuclear Information System (INIS)

    Zarling, J.P.; Swanson, R.B.; Logan, R.R.

    1989-09-01

    The ninety-ninth US Congress commissioned a six-state food irradiation research and development program to evaluate the commercial potential of this technology. Hawaii, Washington, Iowa, Oklahoma and Florida as well as Alaska have participated in the national program; various food products including fishery products, red meats, tropical and citrus fruits and vegetables have been studied. The purpose of the Alaskan study was to review and evaluate those factors related to the technical and economic feasibility of an irradiator in Alaska. This options analysis study will serve as a basis for determining the state's further involvement in the development of food irradiation technology

  12. Slope failure simulations with MPM

    NARCIS (Netherlands)

    Vardon, P.J.; Wang, B.; Hicks, M.A.

    2017-01-01

    The simulation of slope failures, including both failure initiation and development, has been modelled using the material point method (MPM). Numerical case studies involving various slope angles, heterogeneity and rainfall infiltration are presented. It is demonstrated that, by utilising a

  13. Slope Failure Simulations with MPM

    NARCIS (Netherlands)

    Vardon, P.J.; Wang, B.; Hicks, M.A.

    2017-01-01

    The simulation of slope failures, including both failure initiation and development, has been modelled using the material point method. By utilising a constitutive model which encompasses, in a simplified manner, both pre- and post-failure behaviour, the majority of types of geotechnical slope

  14. Case Study on Ancestry Estimation in an Alaskan Native Family: Identity and Safeguards Against Reductionism.

    Science.gov (United States)

    Bader, Alyssa C; Malhi, Ripan S

    2015-10-01

    Understanding the complexities of ancestry-related identity is a necessary component of ethically sound research related to the genetic ancestry of modern-day communities. This is especially true when working with indigenous populations, given the legal and social implications that genetic ancestry interpretations may have in these communities. This study employs a multicomponent approach to explore the intricacies of ancestry-related identity within one extended family with members who identify as Alaskan Native. The seven participants were interviewed about their own self-identity, perceptions regarding genetic ancestry estimation, and their knowledge of oral family history. Additionally, each participant consented to having his or her genetic ancestry estimated. The researchers also surveyed ancestry-related documents, such as census records, birth certificates, and Certificates of Indian Blood. These three different perspectives-oral family history and self-identity, genetic ancestry estimation, historical and legal documentation-illustrate the complex nature of ancestry-related identity within the context of indigenous and colonial interactions in North America. While estimates of genetic ancestry broadly reflected each individual's self-reported biogeographic ancestry and supported all described and historically reported biological relationships, the estimates did not always match federally recorded blood quantum values, nor did they provide any information on relationships at the tribe or clan level. Employing a multicomponent approach and engaging study participants may help to safeguard against genetic essentialism and provide a more nuanced understanding of ancestry-related identity within a larger political, legal, and historical context.

  15. Attitudes toward harm reduction and abstinence-only approaches to alcohol misuse among Alaskan college students

    Directory of Open Access Journals (Sweden)

    Monica C. Skewes

    2013-08-01

    Full Text Available Background. Harm reduction is a public health approach that aims to guide hazardous drinkers to change unsafe drinking and minimize alcohol-related consequences without requiring abstinence. In contrast, abstinence-based interventions are designed for people with more severe alcohol problems and they aim to eliminate consequences via complete abstinence from alcohol. Current best practices for treating college student alcohol misuse involve harm reduction strategies, but no research has been conducted examining students’ perceptions of these strategies. Objective. Understanding attitudes is critical prior to the implementation of an intervention in a new setting, particularly when attitudes may serve as barriers to treatment enrolment and retention. For this reason, we sought to examine attitudes toward contrasting alcohol misuse interventions among college students in two large public universities in the circumpolar north. Design. A web-based survey was conducted with 461 students from two public universities in Alaska. Participants completed questionnaires assessing attitudes toward alcohol treatment, current drinking behaviour, and demographic information. Results. Findings indicated that emerging adult (18–25 years old students who would be targets of future interventions (hazardous drinkers evidenced more positive attitudes toward harm reduction than abstinence-only approaches. Conclusion. This research provides support for the implementation of harm reduction intervention strategies for Alaskan college students who misuse alcohol. It is likely that harm reduction will be acceptable in this population.

  16. Phlorotannins from Alaskan Seaweed Inhibit Carbolytic Enzyme Activity

    Directory of Open Access Journals (Sweden)

    Joshua Kellogg

    2014-10-01

    Full Text Available Global incidence of type 2 diabetes has escalated over the past few decades, necessitating a continued search for natural sources of enzyme inhibitors to offset postprandial hyperglycemia. The objective of this study was to evaluate coastal Alaskan seaweed inhibition of α-glucosidase and α-amylase, two carbolytic enzymes involved in serum glucose regulation. Of the six species initially screened, the brown seaweeds Fucus distichus and Alaria marginata possessed the strongest inhibitory effects. F. distichus fractions were potent mixed-mode inhibitors of α-glucosidase and α-amylase, with IC50 values of 0.89 and 13.9 μg/mL, respectively; significantly more efficacious than the pharmaceutical acarbose (IC50 of 112.0 and 137.8 μg/mL, respectively. The activity of F. distichus fractions was associated with phlorotannin oligomers. Normal-phase liquid chromatography-mass spectrometry (NPLC-MS was employed to characterize individual oligomers. Accurate masses and fragmentation patterns confirmed the presence of fucophloroethol structures with degrees of polymerization from 3 to 18 monomer units. These findings suggest that coastal Alaskan seaweeds are sources of α-glucosidase and α-amylase inhibitory phlorotannins, and thus have potential to limit the release of sugar from carbohydrates and thus alleviate postprandial hyperglycemia.

  17. Analysis of Alaskan burn severity patterns using remotely sensed data

    Science.gov (United States)

    Duffy, P.A.; Epting, J.; Graham, J.M.; Rupp, T.S.; McGuire, A.D.

    2007-01-01

    Wildland fire is the dominant large-scale disturbance mechanism in the Alaskan boreal forest, and it strongly influences forest structure and function. In this research, patterns of burn severity in the Alaskan boreal forest are characterised using 24 fires. First, the relationship between burn severity and area burned is quantified using a linear regression. Second, the spatial correlation of burn severity as a function of topography is modelled using a variogram analysis. Finally, the relationship between vegetation type and spatial patterns of burn severity is quantified using linear models where variograms account for spatial correlation. These results show that: 1) average burn severity increases with the natural logarithm of the area of the wildfire, 2) burn severity is more variable in topographically complex landscapes than in flat landscapes, and 3) there is a significant relationship between burn severity and vegetation type in flat landscapes but not in topographically complex landscapes. These results strengthen the argument that differential flammability of vegetation exists in some boreal landscapes of Alaska. Additionally, these results suggest that through feedbacks between vegetation and burn severity, the distribution of forest vegetation through time is likely more stable in flat terrain than it is in areas with more complex topography. ?? IAWF 2007.

  18. Investigating Alaskan methane and carbon dioxide fluxes using measurements from the CARVE tower

    Directory of Open Access Journals (Sweden)

    A. Karion

    2016-04-01

    Full Text Available Northern high-latitude carbon sources and sinks, including those resulting from degrading permafrost, are thought to be sensitive to the rapidly warming climate. Because the near-surface atmosphere integrates surface fluxes over large ( ∼  500–1000 km scales, atmospheric monitoring of carbon dioxide (CO2 and methane (CH4 mole fractions in the daytime mixed layer is a promising method for detecting change in the carbon cycle throughout boreal Alaska. Here we use CO2 and CH4 measurements from a NOAA tower 17 km north of Fairbanks, AK, established as part of NASA's Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE, to investigate regional fluxes of CO2 and CH4 for 2012–2014. CARVE was designed to use aircraft and surface observations to better understand and quantify the sensitivity of Alaskan carbon fluxes to climate variability. We use high-resolution meteorological fields from the Polar Weather Research and Forecasting (WRF model coupled with the Stochastic Time-Inverted Lagrangian Transport model (hereafter, WRF-STILT, along with the Polar Vegetation Photosynthesis and Respiration Model (PolarVPRM, to investigate fluxes of CO2 in boreal Alaska using the tower observations, which are sensitive to large areas of central Alaska. We show that simulated PolarVPRM–WRF-STILT CO2 mole fractions show remarkably good agreement with tower observations, suggesting that the WRF-STILT model represents the meteorology of the region quite well, and that the PolarVPRM flux magnitudes and spatial distribution are generally consistent with CO2 mole fractions observed at the CARVE tower. One exception to this good agreement is that during the fall of all 3 years, PolarVPRM cannot reproduce the observed CO2 respiration. Using the WRF-STILT model, we find that average CH4 fluxes in boreal Alaska are somewhat lower than flux estimates by Chang et al. (2014 over all of Alaska for May–September 2012; we also find that enhancements appear

  19. Performance of the Bowen ratio systems on a 22 deg slope

    Science.gov (United States)

    Nie, D.; Flitcroft, I.; Kanemasu, E. T.

    1990-01-01

    The Bowen ratio energy balance technique was used to assess the energy fluxes on inclined surfaces during the First ISLSCP Field Experiment (FIFE). Since air flow over sloping surface may differ from that over flat terrain, it is important to examine whether Bowen ratio measurements taken on sloping surfaces are valid. In this study, the suitability of using the Bowen ratio technique on sloping surfaces was tested by examining the assumptions that the technique requires for valid measurements. This was accomplished by studying the variation of Bowen ratio measurements along a selected slope at the FIFE site. In September 1988, four Bowen ratio systems were set up in a line along the 22 degree north-facing slope with northerly air flow (wind went up the slope). In July of 1989, six Bowen ratio systems were similarly installed with southerly air flow (the wind went down slope). Results indicated that, at distances between 10 to 40 meters from the top of the slope, no temperature or vapor pressure gradient parallel to the slope was detected. Uniform Bowen ratio values were obtained on the slope, and thus the sensible or latent heat flux should be similar along the slope. This indicates that the assumptions for valid flux measurements are reasonably met at the slope. The Bowen ratio technique should give the best estimates of the energy fluxes on slopes similar to that in this study.

  20. Do limiting factors at Alaskan treelines shift with climatic regimes?

    International Nuclear Information System (INIS)

    Ohse, B; Jansen, F; Wilmking, M

    2012-01-01

    Trees at Alaskan treelines are assumed to be limited by temperature and to expand upslope and/or to higher latitudes with global warming. However, recent studies describe negative temperature responses and drought stress of Alaskan treeline trees in recent decades. In this study, we have analyzed the responses of treeline white spruce to temperature and precipitation according to different climatic regimes in Alaska, described as negative (cool) and positive (warm) phases of the Pacific Decadal Oscillation (PDO). We found that in three consecutive phases (positive from 1925–46, negative from 1947–76, and positive again from 1977–98), the growth responses to temperature and precipitation differed markedly. Before 1947, in a phase of warm winters and with summer temperatures being close to the century mean, the trees at most sites responded positively to summer temperature, as one would expect from treeline trees at northern high latitudes. Between 1947 and 1976, a phase of cold winters and average summers, the trees showed similar responses, but a new pattern of negative responses to the summer temperature of the year prior to growth coupled with positive responses to the precipitation in the same year emerged at some sites. As the precipitation was relatively low at those sites, we assume that drought stress might have played a role. However, the climate responses were not uniform but were modified by regional gradients (trees at northern sites responded more often to temperature than trees at southern sites) and local site conditions (forest trees responded more often to precipitation than treeline trees), possibly reflecting differences in energy and water balance across regions and sites, respectively. However, since the shift in the PDO in 1976 from a negative to a positive phase, the trees’ climate–growth responses are much less pronounced and climate seems to have lost its importance as a limiting factor for the growth of treeline white spruce. If

  1. Slope failure investigation management system.

    Science.gov (United States)

    2013-03-01

    Highway slopes are exposed to a variety of environmental and climatic conditions, such as deforestation, cycles of : freezing and thawing weather, and heavy storms. Over time, these climatic conditions, in combination with other : factors such as geo...

  2. Light and Dark Slope Streaks

    Science.gov (United States)

    2004-01-01

    21 July 2004 Dark slope streaks are a common feature on slopes thickly-mantled by dust, especially in the Tharsis, Arabia, and western Amazonis regions of Mars. Less common are light-toned slope streaks, which often occur in the same area as dark streaks. They are most common in Arabia Terra, and some are shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Slope streaks are probably the result of sudden avalanches of extremely dry dust. The behavior of the avalanching dust is somewhat fluid-like, and new streaks have been observed to form over intervals of a few months to a Mars year. This image is located near 13.4oN, 340.3oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  3. Compost for steep slope erosion.

    Science.gov (United States)

    2008-06-01

    This study was initiated to develop guidelines for maintenance erosion control measures for steep slopes. The study focused on evaluating and monitoring KY-31 fescue germination rates using two media treatments 1) 100 percent by weight compost and 2)...

  4. Applications of remote sensing data to the Alaskan environment

    Science.gov (United States)

    Belon, A. E.; Iller, J. M.

    1973-01-01

    The ERTS program provides a means to overcome the formidable logistic and economic costs of preparing environmental surveys of the vast and relatively unexplored regions of Alaska. There is an excellent potential in satellite remote sensing to benefit Federal, state, local, and private agencies, by providing a new synoptic data base which is necessary for the preparation of the needed surveys and the search for solutions to environmental management problems. One approach in coupling satellite data to Alaskan problems is a major program initiated by the University of Alaska and funded by NASA's Goddard Space Flight Center. This included 12 projects whose aims were to study the feasibility of applying ERTS data to the disciplines of ecology, agriculture, hydrology, wildlife management, oceanography, geology, glaciology, volcanology, and archaeology.

  5. Lessons learned in managing crowdsourced data in the Alaskan Arctic.

    Science.gov (United States)

    Mastracci, Diana

    2017-04-01

    There is perhaps no place in which the consequences of global climate change can be felt more acutely than the Arctic. However, due to lack of measurements at the high latitudes, validation processes are often problematic. Citizen science projects, co-designed together with Native communities at the interface of traditional knowledge and scientific research, could play a major role in climate change adaptation strategies by advancing knowledge of the Arctic system, strengthening inter-generational bonds and facilitating improved knowledge transfer. This presentation will present lessons learned from a pilot project in the Alaskan Arctic, in which innovative approaches were used to design climate change adaptation strategies to support young subsistence hunters in taking in-situ measurements whilst out on the sea-ice. Both the socio-cultural and hardware/software challenges presented in this presentation, could provide useful guidance for future programs that aim to integrate citizens' with scientific data in Arctic communities.

  6. Haemosporidian parasite infections in grouse and ptarmigan: Prevalence and genetic diversity of blood parasites in resident Alaskan birds

    Science.gov (United States)

    Smith, Matthew M.; Van Hemert, Caroline R.; Merizon, Richard

    2016-01-01

    Projections related to future climate warming indicate the potential for an increase in the distribution and prevalence of blood parasites in northern regions. However, baseline data are lacking for resident avian host species in Alaska. Grouse and ptarmigan occupy a diverse range of habitat types throughout the northern hemisphere and are among the most well-known and important native game birds in North America. Information regarding the prevalence and diversity of haemosporidian parasites in tetraonid species is limited, with few recent studies and an almost complete lack of genetic data. To better understand the genetic diversity of haemosporidian parasites in Alaskan tetraonids and to determine current patterns of geographic range and host specificity, we used molecular methods to screen 459 tissue samples collected from grouse and ptarmigan species across multiple regions of Alaska for infection by Leucocytozoon, Haemoproteus, and Plasmodium blood parasites. Infections were detected in 342 individuals, with overall apparent prevalence of 53% for Leucocytozoon, 21% for Haemoproteus, and 9% for Plasmodium. Parasite prevalence varied by region, with different patterns observed between species groups (grouse versus ptarmigan). Leucocytozoon was more common in ptarmigan, whereas Haemoproteus was more common in grouse. We detected Plasmodium infections in grouse only. Analysis of haemosporidian mitochondrial DNA cytochrome b sequences revealed 23 unique parasite haplotypes, several of which were identical to lineages previously detected in other avian hosts. Phylogenetic analysis showed close relationships between haplotypes from our study and those identified in Alaskan waterfowl for Haemoproteus and Plasmodium parasites. In contrast, Leucocytozoon lineages were structured strongly by host family. Our results provide some of the first genetic data for haemosporidians in grouse and ptarmigan species, and provide an initial baseline on the prevalence and diversity

  7. 16 determination of posterior tibia slope and slope deterioration with ...

    African Journals Online (AJOL)

    Orth (SA), FCS (ECSA), Consultant Orthopaedic Surgeon, P.O. Box. 84074, Mombasa, Kenya. Email: michenimuthuuri@yahoo.com. ABSTRACT. Background: The posterior inclination of the tibia plateaux relative to the longitudinal axis of the tibia is referred to as the Posterior Tibia Slope (PTS). Fore knowledge of the mean ...

  8. Evolution of steep Martian slopes

    Science.gov (United States)

    Sullivan, Robert John, Jr.

    1992-01-01

    The physical properties and evolution of steep slopes on the planet Mars are examined. Where martian slopes are steepest and of greatest relief, the slope morphology is distinctive and characterized by regular, alternating spurs and gullies. Previous workers identified these martian gullies as dry debris avalanche chutes, partially because a nonspecific 'dry mass-wasting' explanation seemed compatible, initially, with current surface conditions. An evacuated avalanche chute provides the opportunity to back analyze the stability of the mobile layer of the chute at the time of its failure. For the martian slope problem a new stability back-analysis technique was developed which incorporates the third dimension (chute width) into the back-analysis calculation, allowing unambiguous determination of the average cohesion and angle of internal friction of the mobile layer. A series of trials was performed to investigate the effects of gravitational acceleration, average slope angle, and average mobile layer density, cohesion, and angle of internal friction on the size and shape of the transverse chute cross-section. Results indicate that: (1) variations in density, gravitational acceleration, and cohesion affect the overall size of the cross-section but not its width:depth ratio, and (2) the contrast between average slope angle and angle of internal friction is most influential on the width:depth ratio of the cross-section. The difference between these two parameters is inversely proportional to the width:depth ratio. Application of the three-dimensional back-analysis technique to proposed martian avalanche chutes yields values of cohesion and angle of internal friction of the mobile layers that are similar mechanically (without genetic implications) to those of terrestrial glacial till, a poorly sorted material with moderate inter-grain cohesion, or lunar soils under normal stresses representative of (lunar) depths of between ten and twenty meters. Material of these

  9. Holocene Paleoceanography of the Chukchi Sea / Alaskan Margin, Western Arctic Ocean

    Science.gov (United States)

    McKay, J. L.; Hillaire-Marcel, C.; de Vernal, A.; Polyak, L.; Darby, D.

    2006-12-01

    A multi-proxy approach to the analysis of deep-sea sediment cores has been used to investigate paleoceanographical changes in the western Arctic. This approach includes stable isotopic analysis of{ \\it Neogloboquadrina pachyderma} (Np), the dominant planktonic foraminifera in the Arctic, which lives along the pycnocline that separates the cold, low salinity surface water from the underlying warmer water mass of North Atlantic origin. Palynological analyses focus on dinocyst assemblages that are usually well preserved in Arctic seas and include several species, thus allowing treatment of data (modern analogue technique) for quantitative reconstruction of sea-surface parameters, including maximum summer temperature and seasonal extent of sea-ice cover (cf. de Vernal et al., Paleoceanography, 2005). Work in the Chukchi Sea has shown that larger (i.e., heavier, possibly mature) specimens of Np are characterized by a lower oxygen isotopic composition relative to smaller (i.e., possibly juvenile) specimens that live at shallower depths, reflecting calcification of larger Np shells on top of the warmer North Atlantic Water mass (cf. Hillaire-Marcel et al., Quat. Sci. Rev., 2004). These results suggest that a reverse thermocline (warmer water underlying colder water) persisted throughout the Holocene, and that the gradients between surface and subsurface waters were stronger during the early Holocene, which may indicate greater influx of North Atlantic Water at this time. It is also possible that the isotopic composition of the planktonic foraminifera was influenced by enhanced sea-ice formation and sinking of isotopically-light brines during the early Holocene. This second hypothesis is compatible with reconstructions from dinocysts that suggest maximum sea-ice extent during the early Holocene. Preliminary results from core HLY0501-05 collected in the Beaufort Sea off the Alaskan Margin during Leg 1 of the HOTRAX 2005 Expedition show results consistent with those of the

  10. Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR/Normal Incidence Multifilter Radiometer (NIMFR Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM North Slope of Alaska (NSA and Southern Great Plains (SGP Sites

    Directory of Open Access Journals (Sweden)

    James Barnard

    2013-09-01

    Full Text Available Well-known cloud-screening algorithms, which are designed to remove cloud-contaminated aerosol optical depths (AOD from Multifilter Rotating Shadowband Radiometer (MFRSR and Normal Incidence Multifilter Radiometer (NIMFR measurements, have exhibited excellent performance at many middle-to-low latitude sites around world. However, they may occasionally fail under challenging observational conditions, such as when the sun is low (near the horizon and when optically thin clouds with small spatial inhomogeneity occur. Such conditions have been observed quite frequently at the high-latitude Atmospheric Radiation Measurement (ARM North Slope of Alaska (NSA sites. A slightly modified cloud-screening version of the standard algorithm is proposed here with a focus on the ARM-supported MFRSR and NIMFR data. The modified version uses approximately the same techniques as the standard algorithm, but it additionally examines the magnitude of the slant-path line of sight transmittance and eliminates points when the observed magnitude is below a specified threshold. Substantial improvement of the multi-year (1999–2012 aerosol product (AOD and its Angstrom exponent is shown for the NSA sites when the modified version is applied. Moreover, this version reproduces the AOD product at the ARM Southern Great Plains (SGP site, which was originally generated by the standard cloud-screening algorithms. The proposed minor modification is easy to implement and its application to existing and future cloud-screening algorithms can be particularly beneficial for challenging observational conditions.

  11. 40 CFR 408.40 - Applicability; description of the non-remote Alaskan crab meat processing subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the non-remote Alaskan crab meat processing subcategory. 408.40 Section 408.40 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Crab Meat Processing Subcategory § 408.40 Applicability...

  12. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Science.gov (United States)

    2010-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  13. Morphologic and sedimentologic characteristics of continental slope box slides offshore Fraser Island, Queensland, Australia

    Science.gov (United States)

    Fletcher, Melissa; Hubble, Thomas; Clarke, Samantha; Airey, David; Yu, Phyllis; Southern Surveyor V01-2013, Scientific Party RV

    2014-05-01

    The Fraser Island Slide complex is located on eastern Australia's continental slope offshore Fraser Island in southern Queensland. Morphologic, sedimentologic and geomechanical properties data for two submarine landslides, the 'North Fraser Island Upper Slope Slide' (upper slope slide) and the 'Fraser Island Middle Slope Slide' (middle slope slide) are described. Both of these features are box-shaped, slide scars from which rectangular slabs of material have been shed. The upper slope slide is situated at a water depth of approximately 750 m at the northern end of the Fraser Canyon. The head of this slide has apparently detached from a structural surface comprised of a Miocene reef complex located beneath the continental shelf edge; this slide is estimated to be 25 square kilometres in area and an average of 100m thick. The middle slope slide is situated in 1500 m of water at the southern end of the Fraser Canyon. It estimated to be 12 square kilometres in area and 50 m thick. Cores taken in the continental slope within both slides are long (upper slope 5.65 m, middle slope 3.64 m) and are dominantly comprised of hemipelagic mud. Cores taken adjacent to both slides are short (upper slope 1.33m, middle slope 0.43m) and terminate in stiff muds of suspected Miocene or Pliocene age. Additionally, the 1.33 m core on the slope adjacent to the upper slide presents a near surface layer of upper-fining of coarse to fine shelly sand which we interpret to be a turbidite deposit, this layer was deposited within hemipelagic muds which are ubiquitously present on the upper eastern Australian Continental Slope in New South Wales and Southern Queensland.

  14. Ecology of invasive Melilotus albus on Alaskan glacial river floodplains

    Science.gov (United States)

    Conn, Jeff S.; Werdin-Pfisterer, Nancy R.; Beattie, Katherine L.; Densmore, Roseann V.

    2011-01-01

    Melilotus albus (white sweetclover) has invaded Alaskan glacial river floodplains. We measured cover and density of plant species and environmental variables along transects perpendicular to the Nenana, Matanuska, and Stikine Rivers to study interactions between M. albus and other plant species and to characterize the environment where it establishes. Melilotus albus was a pioneer species on recently disturbed sites and did not persist into closed canopy forests. The relationships between M. albus cover and density and other species were site-specific.Melilotus albus was negatively correlated with native species Elaeagnus commutata at the Nenana River, but not at the Matanuska River. Melilotus albus was positively correlated with the exotic species Crepis tectorumand Taraxacum officinale at the Matanuska River and T. officinale on the upper Stikine River. However, the high density of M. albus at a lower Stikine River site was negatively correlated with T. officinale and several native species including Lathyrus japonicus var. maritimus and Salix alaxensis. Glacial river floodplains in Alaska are highly disturbed and are corridors for exotic plant species movement. Melilotus albus at moderate to low densities may facilitate establishment of exotic species, but at high densities can reduce the cover and density of both exotic and native species.

  15. Symptoms of Alcohol Dependence Predict Suicide Ideation Among Alaskan Undergraduates.

    Science.gov (United States)

    DeCou, Christopher R; Skewes, Monica C

    2016-05-01

    Previous research has demonstrated an association between alcohol-related problems and suicidal ideation (SI). The present study evaluated, simultaneously, alcohol consequences and symptoms of alcohol dependence as predictors of SI after adjusting for depressive symptoms and alcohol consumption. A sample of 298 Alaskan undergraduates completed survey measures, including the Young Adult Alcohol Consequences Questionnaire, the Short Alcohol Dependence Data Questionnaire, and the Beck Depression Inventory - II. The association between alcohol problems and SI status was evaluated using sequential logistic regression. Symptoms of alcohol dependence (OR = 1.88, p alcohol-related consequences (OR = 1.01, p = .95), emerged as an independent predictor of SI status above and beyond depressive symptoms (OR = 2.39, p alcohol consumption (OR = 1.08, p = .39). Alcohol dependence symptoms represented a unique risk for SI relative to alcohol-related consequences and alcohol consumption. Future research should examine the causal mechanism behind the relationship between alcohol dependence and suicidality among university students. Assessing the presence of dependence symptoms may improve the accuracy of identifying students at risk of SI.

  16. Interannual variability in lower trophic levels on the Alaskan Shelf

    Science.gov (United States)

    Batten, Sonia D.; Raitsos, Dionysios E.; Danielson, Seth; Hopcroft, Russell; Coyle, Kenneth; McQuatters-Gollop, Abigail

    2018-01-01

    This study describes results from the first 16 years of the Continuous Plankton Recorder (CPR) program that has sampled the lower trophic levels (restricted to larger, hard-shelled phytoplankton and robust zooplankton taxa) on the Alaskan shelf. Sampling took place along transects from the open ocean across the shelf (to the entrance to Prince William Sound from 2000 to 2003 and into Cook Inlet from 2004 to 2015) to provide plankton abundance data, spring through autumn of each year. We document interannual variability in concentration and composition of the plankton community of the region over this time period. At least in part and through correlative relationships, this can be attributed to changes in the physical environment, particularly direct and indirect effects of temperature. For example; spring mixed layer depth is shown to influence the timing of the spring diatom peak and warmer years are biased towards smaller copepod species. A significant positive relationship between temperature, diatom abundance and zooplankton biomass existed from 2000 to 2013 but was not present in the warm years of 2014 and 2015. These results suggest that anomalous warming events, such as the "heat wave" of 2014-2015, could fundamentally influence typical lower trophic level patterns, possibly altering trophic interactions.

  17. Contaminants in arctic snow collected over northwest Alaskan sea ice

    Science.gov (United States)

    Garbarino, J.R.; Snyder-Conn, E.; Leiker, T.J.; Hoffman, G.L.

    2002-01-01

    Snow cores were collected over sea ice from four northwest Alaskan Arctic estuaries that represented the annual snowfall from the 1995-1996 season. Dissolved trace metals, major cations and anions, total mercury, and organochlorine compounds were determined and compared to concentrations in previous arctic studies. Traces (marine snow (n = 15) in relation to snow from arctic terrestrial studies, whereas cations associated with terrigenous sources, such as aluminum, frequently were lower over the sea ice. One Kasegaluk Lagoon site (Chukchi Sea) had especially high concentrations of total mercury (mean = 214 ng L-1, standard deviation = 5 ng L-1), but no methyl mercury was detected above the method detection limit (0.036 ng L-1) at any of the sites. Elevated concentrations of sulfate, mercury, and certain heavy metals might indicate mechanisms of contaminant loss from the arctic atmosphere over marine water not previously reported over land areas. Scavenging by snow, fog, or riming processes and the high content of deposited halides might facilitate the loss of such contaminants from the atmosphere. Both the mercury and chlorpyrifos concentrations merit further investigation in view of their toxicity to aquatic organisms at low concentrations.

  18. A Formal Messaging Notation for Alaskan Aviation Data

    Science.gov (United States)

    Rios, Joseph L.

    2015-01-01

    Data exchange is an increasingly important aspect of the National Airspace System. While many data communication channels have become more capable of sending and receiving data at higher throughput rates, there is still a need to use communication channels efficiently with limited throughput. The limitation can be based on technological issues, financial considerations, or both. This paper provides a complete description of several important aviation weather data in Abstract Syntax Notation format. By doing so, data providers can take advantage of Abstract Syntax Notation's ability to encode data in a highly compressed format. When data such as pilot weather reports, surface weather observations, and various weather predictions are compressed in such a manner, it allows for the efficient use of throughput-limited communication channels. This paper provides details on the Abstract Syntax Notation One (ASN.1) implementation for Alaskan aviation data, and demonstrates its use on real-world aviation weather data samples as Alaska has sparse terrestrial data infrastructure and data are often sent via relatively costly satellite channels.

  19. Emissions of biogenic sulfur gases from Alaskan tundra

    Science.gov (United States)

    Hines, Mark E.; Morrison, Michael C.

    1992-01-01

    Results of sulfur emission measurements made in freshwater and marine wetlands in Alaskan tundra during the Arctic Boundary Layer Expedition 2A (ABLE 3A) in July 1988 are presented. The data indicate that this type of tundra emits very small amounts of gaseous sulfur and, when extrapolated globally, accounts for a very small percentage of the global flux of biogenic sulfur to the atmosphere. Sulfur emissions from marine sites are up to 20-fold greater than fluxes from freshwater habitats and are dominated by dimethyl sulfide (DMS). Highest emissions, with a mean of 6.0 nmol/sq m/h, occurred in water-saturated wet meadow areas. In drier upland tundra sites, highest fluxes occurred in areas inhabited by mixed vegetation and labrador tea at 3.0 nmol/sq m/h and lowest fluxes were from lichen-dominated areas at 0.9 nmol/sq m/h. DMS was the dominant gas emitted from all these sites. Emissions of DMS were highest from intertidal soils inhabited by Carex subspathacea.

  20. Impact of slope inclination on salt accumulation

    Science.gov (United States)

    Nachshon, Uri

    2017-04-01

    Field measurements indicated on high variability in salt accumulation along natural and cultivated slopes, even for relatively homogeneous soil conditions. It was hypothesised that slope inclination has an impact on the location of salt accumulation along the slope. A set of laboratory experiments and numerical models were used to explore the impact of slope inclination on salt accumulation. It was shown, experimentally, that for conditions of saline water source at the lower boundary of the slope - salt accumulates in low concentrations and homogeneously along the entire slope, for moderate slopes. However, as inclination increases high salt concentrations were observed at the upper parts of the slope, leaving the lower parts of the slope relatively free of salt. The traditional flow and transport models did not predict the experimental observations as they indicated also for the moderate slopes on salt accumulation in the elevated parts of the slope, away of the saline water source. Consequently - a conceptual model was raised to explain the laboratory observations. It was suggested that the interactions between slope angle, evaporation rates, hydraulic conductivity of the medium and distribution of wetness along the slope affect the saline water flow path through the medium. This lead to preferential flow path close to the soil-atmosphere interface for the steep slopes, which leads to constant wash of the salts from the evaporation front upward towards the slope upper parts, whereas for the moderate slopes, flow path is below the soil-atmosphere interface, therefore salt that accumulates at the evaporation front is not being transported upward. Understanding of salt dynamics along slopes is important for agricultural and natural environments, as well as for civil engineering purposes. Better understanding of the salt transport processes along slopes will improve our ability to minimize and to cope with soil salinization processes. The laboratory experiments and

  1. Do Spawning Salmon Contribute Marine-Derived Contaminants to Southeast Alaskan Streams?

    Science.gov (United States)

    Nagorski, S. A.; Hudson, J. P.; Fellman, J.; Hood, E. W.; Vermilyea, A.; Krabbenhoft, D. P.; Ylitalo, G.

    2016-12-01

    Pacific salmon are well known contributors of marine-derived nutrients and carbon to freshwater systems where they spawn and die. A potentially negative side effect of their freshwater spawning legacy is their additional contribution of pollutants accumulated during the marine phase of their life cycle. Alaskan salmon, which undergo the majority of their bodily growth in the North Pacific, are being exposed to rising concentrations of pollutants in the waters and foodwebs of the north Pacific. In this study we investigated the contribution of mercury and persistent organic pollutants (POPs) by spawning Pacific salmon to five streams in the vicinity of Juneau, Alaska. Using a nested experimental design inherent in streams with natural migration barriers or steep density gradients, we collected samples from stream reaches with and without spawning salmon. We measured total and methyl mercury in filtered water, suspended particulates, streambed sediment, biofilm on incubated leaf packs, two taxa of benthic macroinvertebrate larvae, and rearing and/or resident fishes. The benthic macroinvertebrates and fishes were also analyzed for a suite of POPs, consisting of historic and current use pesticides and historic and urban use chemicals. For most parameters, contaminant concentrations were higher in the lower reaches where salmon spawners were present, with stronger effects in the streams with higher spawner densities. For example, in the two streams with the highest spawner densities, filtered methylmercury was an order of magnitude higher in the lower stream reach and comprised up to 33% of the total mercury. Alder leaf packs resulted in particularly consistent spatial patterns, while benthic macroinvertebrate larvae results were the least spatially consistent for both mercury and POPs. Although fish tissue mercury concentrations were not uniformly higher in lower stream reaches across our 5 study streams due to upstream sources of mercury and different fish species and

  2. Clouds and snowmelt on the north slope of Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Stamnes, K.; Bowling, S.A. [Univ. of Alaska, Fairbanks, AK (United States)

    1996-04-01

    Clouds have a large effect on the radiation field. Consequently, possible changes in cloud properties may have a very substantial impact on climate. Of all natural surfaces, seasonal snow cover has the highest surface albedo, which is one of the most important components of the climatic system. Interactions between clouds and seasonal snow cover are expected to have a significant effect on climate and its change at high latitudes. The purpose of this paper is to investigate the sensitivity of the surface cloud-radiative forcing during the period of snowmelt at high latitudes. The primary variables investigated are cloud liquid path (LWP) and droplet equivalent radius (r{sub e}). We will also examine the sensitivity of the surface radiative fluxes to cloud base height and cloud base temperature.

  3. North Slope mobile technology and its application to spill response

    International Nuclear Information System (INIS)

    Mabile, N.J.; Helinski, R.

    1992-01-01

    At ARCO Alaska's Prudhoe Bay operation, improved preparedness for oil spill response has been achieved by applying mobile technology according to an innovative concept. To ensure safe and efficient deployment of resources during a spill response, a rapid deployment equipment delivery system was developed. This multi-functional, modularized system was based on a previously developed chemical delivery system consisting of a primary transport truck equipped with a Dempsey Dumpster Dinosaur skid. This same modularized concept was used for spill response with the substitution of function-specific spill response vans in place of chemical transport tanks. Within this concept, skid-mounted mission-specific vans are rapidly deployed to multiple sites in a fire brigade type of response. Skid-mounted units include land and water containment, recovery, boom deployment, command center, generator skid, restroom facility, and skimmer units. 4 figs

  4. A genetic dissection of breed composition and performance enhancement in the Alaskan sled dog

    Directory of Open Access Journals (Sweden)

    Runstadler Jonathan

    2010-07-01

    Full Text Available Abstract Background The Alaskan sled dog offers a rare opportunity to investigate the development of a dog breed based solely on performance, rather than appearance, thus setting the breed apart from most others. Several established breeds, many of which are recognized by the American Kennel Club (AKC, have been introduced into the sled dog population to enhance racing performance. We have used molecular methods to ascertain the constitutive breeds used to develop successful sled dog lines, and in doing so, determined the breed origins of specific performance-related behaviors. One hundred and ninety-nine Alaskan sled dogs were genotyped using 96 microsatellite markers that span the canine genome. These data were compared to that from 141 similarly genotyped purebred dog breeds. Sled dogs were evaluated for breed composition based on a variety of performance phenotypes including speed, endurance and work ethic, and the data stratified based on population structure. Results We observe that the Alaskan sled dog has a unique molecular signature and that the genetic profile is sufficient for identifying dogs bred for sprint versus distance. When evaluating contributions of existing breeds we find that the Alaskan Malamute and Siberian Husky contributions are associated with enhanced endurance; Pointer and Saluki are associated with enhanced speed and the Anatolian Shepherd demonstrates a positive influence on work ethic. Conclusion We have established a genetic breed profile for the Alaskan sled dog, identified profile variance between sprint and distance dogs, and established breeds associated with enhanced performance attributes. These data set the stage for mapping studies aimed at finding genes that are associated with athletic attributes integral to the high performing Alaskan sled dog.

  5. VT Lidar Slope (1 meter) - 2005 - Essex

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Essex County 2005 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command...

  6. Gravity-induced stresses in finite slopes

    Science.gov (United States)

    Savage, W.Z.

    1994-01-01

    An exact solution for gravity-induced stresses in finite elastic slopes is presented. This solution, which is applied for gravity-induced stresses in 15, 30, 45 and 90?? finite slopes, has application in pit-slope design, compares favorably with published finite element results for this problem and satisfies the conditions that shear and normal stresses vanish on the ground surface. The solution predicts that horizontal stresses are compressive along the top of the slopes (zero in the case of the 90?? slope) and tensile away from the bottom of the slopes, effects which are caused by downward movement and near-surface horizontal extension in front of the slope in response to gravity loading caused by the additional material associated with the finite slope. ?? 1994.

  7. Carbonate slope morphology revealing bank-to-slope sediment transfer in Little Bahama Bank, Bahamas

    Science.gov (United States)

    Mulder, Thierry; Gillet, Hervé; Hanquiez, Vincent; Ducassou, Emmanuelle; Fauquembergue, Kelly; Conesa, Gilles; Principaud, Mélanie; Le Goff, Johan; Ragusa, Jérémy; Bujan, Stephane; Bashah, Sara

    2017-04-01

    New high-quality multibeam data depict the area located between Little Bahama Bank (LBB, Bahamas) and Blake Plateau. The survey details the morphology of a giant 135-km-long canyon, the Great Abaco Canyon (GAC) and its main characteristics. The canyon main axis runs parallel to the margin. The pathway shows several knickpoints and plunge pools. The most important knickpoint is underlined by an abrupt change in slope of the canyon thalweg. The last one leads to the opening towards the Blake Basin. Its morphologic head forms a vast receptacle but does not represent the main source of material at present. The material supplied through the LBB canyon systems does not reach this area which only shows lineaments related to the pathway of the Antilles current and restricted failure scars. Most of the supply comes from the canyon flanks. In the north, tributary canyons drain the contourite deposits forming large flat plateaus above the drowned carbonate platform of the Blake Plateau. In addition, these contourite plateaus are subjected to translational slides moving towards the northern edge of the canyon forming a dissymmetric debris accumulation along the toe of the north canyon edge. Another source of sediment are two large tributaries connecting the GAC directly to the LBB upper slope. Sub bottom profiles suggest the presence of a turbiditic levee on the tributary canyon sides and inferred turbiditic activity. Little Abaco Canyon (LAC) shows morphologic similarities with GAC but at a smaller size. However, the canyon seems more active in terms of sediment transport. Canyons draining the eastern part of LBB show fresh sedimentary structures (sediment waves) suggesting active sedimentary processes. These structures are made of clean sand with shallow water organisms suggesting a direct supply from the carbonate platform edge. In term of size and morphology, the GAC compares to the largest canyons in siliciclastic environments. Its originality comes from the fact it is

  8. Slope protection for artificial island

    Energy Technology Data Exchange (ETDEWEB)

    Czerniak, M.T.; Collins, J.I.; Shak, A.T.

    1981-08-01

    The technology under development to protect artificial-island production platforms from Arctic sea and ice damage involves three major considerations: (1) sea conditions during the ice-free season, (2) ice conditions during winter, and (3) construction constraints imposed by material availability, transportation problems, and length of the construction season. So far, researchers have evaluated 15 different slope-protection systems on the basis of reliability, construction-cost, and maintenance-cost factors, choosing 8 candidates for wave and ice model testing. The cases of interest involve exploration and production islands in shallow and deeper water applications.

  9. Aerial surveys of endangered whales in the Alaskan Chukchi and western Beaufort Seas, 1990. Final report, Oct-Nov 90

    International Nuclear Information System (INIS)

    Moore, S.E.; Clarke, J.T.

    1991-06-01

    In keeping with the National Environmental Policy Act (1969), the Marine Mammal Protection Act (1972) and the Endangered Species Act (1973), the OCS Lands Act Amendments (1978) established a management policy that included studies in OCS lease sale areas to ascertain potential environmental impacts of oil and gas development on OCS marine coastal environments. The Minerals Management Service (MMS) is the agency responsible for these studies and for the leasing of submerged Federal lands. The report summarizes the 1990 investigations of the distribution, abundance, migration, behavior and habitat relationships of endangered whales in the Alaskan Chukchi and western Beaufort Seas (hereafter, study area); 1990 was the second of a three year (1989-91) study. The Bering Sea stock of bowhead whales (Balaena mysticetus) was the principal species studied, with incidental sightings of all other marine mammals routinely recorded. The 1990 season was compromised by circumstances that restricted the availability of the survey aircraft (Grumman Goose, model G21G) to the period 26 October - 7 November; opportunistic surveys were flown in the study area from 3-25 October. In 1990, there were 14 sightings of 19 bowheads from 9-29 October; 5 whales, including 2 calves, were seen north of the study area. One gray whale, 110 belukhas and 53 polar bears were also seen. Over nine survey seasons (1982-90), there were 240 sightings of 520 bowhead whales and 148 sightings of 398 gray whales

  10. Mycorrhizal aspects in slope stabilisation

    Science.gov (United States)

    Graf, Frank

    2016-04-01

    In order to re-colonise and stabilise slopes affected by superficial soil failure with plants essential requirements have to be met: the plants must grow the plants must survive sustainably plant succession must start and continuously develop These requirements, however, are anything but easy given, particularly under the often hostile environmental conditions dominating on bare and steep slopes. Mycorrhizal fungi, the symbiotic partners of almost all plants used in eco-engineering, are said to improve the plants' ability to overcome periods governed by strongly (growth) limiting factors. Subsequently, results of investigations are presented of mycorrhizal effects on different plant and soil functions related to eco-engineering in general and soil and slope stabilisation in particular. Generally, inoculation yielded higher biomass of the host plants above as well as below ground. Furthermore, the survival rate was higher for mycorrhized compared to non-mycorrhized plants, particularly under extreme environmental conditions. However, the scale of the mycorrhizal impact may be species specific of both the plant host as well as the fungal partner(s) and often becomes evident only after a certain time lag. Depending on the plant-fungus combination the root length per soil volume was found to be between 0 and 2.5 times higher for inoculated compared to non-inoculated specimens. On an alpine graded ski slope the survival of inoculated compared to non-treated Salix herbacea cuttings was significant after one vegetation period only for one of the three added mycorrhizal fungus species. However, after three years all of the inoculated plantlets performed significantly better than the non-inoculated controls. The analysis of the potential for producing and stabilising soil aggregates of five different ectomycorrhizal fungi showed high variation and, for the species Inocybe lacera, no significant difference compared to untreated soil. Furthermore, inoculation of Salix

  11. Novel Florfenicol and Chloramphenicol Resistance Gene Discovered in Alaskan Soil by Using Functional Metagenomics▿

    Science.gov (United States)

    Lang, Kevin S.; Anderson, Janet M.; Schwarz, Stefan; Williamson, Lynn; Handelsman, Jo; Singer, Randall S.

    2010-01-01

    Functional metagenomics was used to search for florfenicol resistance genes in libraries of cloned DNA isolated from Alaskan soil. A gene that mediated reduced susceptibility to florfenicol was identified and designated pexA. The predicted PexA protein showed a structure similar to that of efflux pumps of the major facilitator superfamily. PMID:20543056

  12. Utilization of geothermal energy resources in rural Alaskan communities. Final report, June 1-December 31, 1974

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, R.B.; Leonard, L.; Dinkel, D.H.

    1974-12-01

    Three potential geothermal sites in Alaska are discovered. The history of previous use of the hot springs, the socio-economic factors, energy needs, and total energy utilization plans of selected Alaskan thermal springs are presented. Proposed research programs for the sites and environmental hazards and protection are described. (MHR)

  13. Novel florfenicol and chloramphenicol resistance gene discovered in Alaskan soil by using functional metagenomics.

    Science.gov (United States)

    Lang, Kevin S; Anderson, Janet M; Schwarz, Stefan; Williamson, Lynn; Handelsman, Jo; Singer, Randall S

    2010-08-01

    Functional metagenomics was used to search for florfenicol resistance genes in libraries of cloned DNA isolated from Alaskan soil. A gene that mediated reduced susceptibility to florfenicol was identified and designated pexA. The predicted PexA protein showed a structure similar to that of efflux pumps of the major facilitator superfamily.

  14. EXAMINATION OF THE FEASIBILITY FOR DEMONSTRATION AND USE OF RADIOLUMINESCENT LIGHTS FOR ALASKAN REMOTE RUNWAY LIGHTING

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, G.; Perrigo, L.; Leonard, L.; Hegdal, L

    1984-01-01

    This report examines the feasibility of radioluminescent light applications for rural Alaskan airports. The work presented in this report covers four tasks: State of the Art Evaluation of Radioluminescent Lights, Environmental, Radiological, and Regulatory Evaluations, Engineering Evaluations, and Demonstration Plan Development.

  15. Understanding the Complex Dimensions of the Digital Divide: Lessons Learned in the Alaskan Arctic

    Science.gov (United States)

    Subramony, Deepak Prem

    2007-01-01

    An ethnographic case study of Inupiat Eskimo in the Alaskan Arctic has provided insights into the complex nature of the sociological issues surrounding equitable access to technology tools and skills, which are referred to as the digital divide. These people can overcome the digital divide if they get the basic ready access to hardware and…

  16. An assessment of educational needs in the Alaskan forest products industry.

    Science.gov (United States)

    Jon Thomas; Eric Hansen; Allen M. Brackley

    2005-01-01

    Major changes in federal forest policy in Alaska have resulted in a dramatic downsizing of the state's forest industry. These changes have driven efforts for economic restructuring and improved support for Alaskan communities. The University of Alaska Sitka Forest Products program at the University of Alaska Southeast is one example of efforts to better support...

  17. Alaskan permafrost groundwater storage changes derived from GRACE and ground measurements

    Science.gov (United States)

    Reginald R. Muskett; Vladimir E. Romanovsky

    2011-01-01

    The Arctic is in transition from climate-driven thawing of permafrost. We investigate satellite-derived water equivalent mass changes, snow water equivalent with in situ measurements of runoff and ground-survey derived geoid models from 1999 through 2009. The Alaskan Arctic coastal plain groundwater storage (including wetland bog, thaw pond and lake) is increasing by 1...

  18. Sarcocystis arctica (Apicomplexa: Sarcocystidae): ultrastructural description and its new host record, the Alaskan wolf (Canis lupus

    Science.gov (United States)

    Sarcocystis sarcocysts are common in muscles of herbivores but are rare in muscles of carnivores. Here, we report sarcocysts in muscle of an Alaskan wolf (Canis lupus) from Alaska, USA for the first time. Sarcocysts extracted from tongue of the wolf were up to 900 µm long, slender, and appeared to h...

  19. The Influence of Shales on Slope Instability

    Science.gov (United States)

    Stead, Doug

    2016-02-01

    Shales play a major role in the stability of slopes, both natural and engineered. This paper attempts to provide a review of the state-of-the-art in shale slope stability. The complexities of shale terminology and classification are first reviewed followed by a brief discussion of the important physical and mechanical properties of relevance to shale slope stability. The varied mechanisms of shale slope stability are outlined and their importance highlighted by reference to international shale slope failures. Stability analysis and modelling of anisotropic rock slope masses are briefly discussed and the potential role of brittle rock fracture and damage highlighted. A short review of shale slopes in open pits is presented.

  20. The impacts of the export ban on Alaskan crude oil trade

    International Nuclear Information System (INIS)

    Farah, P.G.; Bausell, C.W.; Vogelsang, A.

    1990-01-01

    The authors investigated the petroleum markets impacts of lifting the ban on Alaska North Slope (ANS) crude oil exports. This paper reports on some aspects of this investigation. The economic analysis relied heavily on the modeling of the ANS crude trade conducted on behalf of GAO by the Energy Information Administration (EIA) using the Transportation and Refining of International Petroleum model (TRIP). In contrast to previous studies, this one suggests that transportation costs may not be the only major factor in the realignment of ANS crude trade in response to lifting the ban. The differences in the yields of ANS crude and various crudes used by refiners in Pacific Rim countries on the one hand, and the product demand slates of the US West Coast and the potential buyers of ANS crude in Pacific Rim may also figure prominently in determining the reallocation of ANS crude if exports are permitted

  1. Potential effects of ocean acidification on Alaskan corals based on calcium carbonate mineralogy composition analysis (NCEI Accession 0157223)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains potential effects of ocean acidification on Alaskan corals based on calcium carbonate mineralogy composition analysis. Effects of...

  2. National Airspace System: Incomplete Transition Back to National Maintenance and Certification Standards in the Federal Aviation Administration's Alaskan Region

    National Research Council Canada - National Science Library

    Dillingham, Gerald

    2001-01-01

    .... Early in 2001, the Federal Labor Relations Authority ruled that FAA must revert back to the national maintenance and certification standards in the Alaskan Region because FAA had not negotiated...

  3. The establishment of Atlantic Water transport as a topographically trapped slope current off Scotland

    Directory of Open Access Journals (Sweden)

    Qin Zhou

    2013-05-01

    Full Text Available Atlantic Water, with its origin in the western Atlantic, enters the Nordic Seas partly as a barotropic current following the continental slope. This water mass is carried across the Atlantic by the baroclinic North Atlantic Current (NAC. When the NAC meets the continental slope at the east side of the Atlantic, some of the transport is converted to barotropic transport over the slope before continuing northward. Here, we show that this baroclinic to barotropic conversion is in agreement with geostrophic theory. Historical observations show that the transport of the slope current increases significantly from the Rockall Channel (RC to the Faroe–Shetland Channel (FSC. Geostrophy predicts that with a northward decreasing buoyancy, baroclinic currents from the west will be transferred into northward topographically steered barotropic flow. We use hydrographic data from two sections crossing the continental slope, one located in the RC and another in the FSC, to estimate baroclinic and barotropic transport changes over the slope, within the framework of geostrophic dynamics. Our results indicate that ~1 Sv of the cross-slope baroclinic flow is mainly converted to northward barotropic transport above the 200–500m isobaths, which is consistent with observed transport changes between the RC and the FSC. Similar processes are also likely to occur further south, along the eastern Atlantic margin. This shows that AW within the slope current in the FSC is derived from both the eastern and the western Atlantic, in agreement with earlier studies of AW inflow to the Nordic Seas.

  4. The Hydromechanics of Vegetation for Slope Stabilization

    Science.gov (United States)

    Mulyono, A.; Subardja, A.; Ekasari, I.; Lailati, M.; Sudirja, R.; Ningrum, W.

    2018-02-01

    Vegetation is one of the alternative technologies in the prevention of shallow landslide prevention that occurs mostly during the rainy season. The application of plant for slope stabilization is known as bioengineering. Knowledge of the vegetative contribution that can be considered in bioengineering was the hydrological and mechanical aspects (hydromechanical). Hydrological effect of the plant on slope stability is to reduce soil water content through transpiration, interception, and evapotranspiration. The mechanical impact of vegetation on slope stability is to stabilize the slope with mechanical reinforcement of soils through roots. Vegetation water consumption varies depending on the age and density, rainfall factors and soil types. Vegetation with high ability to absorb water from the soil and release into the atmosphere through a transpiration process will reduce the pore water stress and increase slope stability, and vegetation with deep root anchoring and strong root binding was potentially more significant to maintain the stability of the slope.

  5. Slope Estimation from ICESat/GLAS

    Directory of Open Access Journals (Sweden)

    Craig Mahoney

    2014-10-01

    Full Text Available We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM. The technique is applied to large footprint waveforms (\\(\\sim\\ mean diameter from the Ice, Cloud and Land Elevation Satellite (ICESat Geoscience Laser Altimeter System (GLAS to produce a slope dataset of near-global coverage at \\(0.5^{\\circ} \\times 0.5^{\\circ}\\ resolution. ISM slope estimates are compared against high resolution airborne LiDAR slope measurements for nine sites across three continents. ISM slope estimates compare better with the aircraft data (R\\(^{2}=0.87\\ and RMSE\\(=5.16^{\\circ}\\ than the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM inferred slopes (R\\(^{2}=0.71\\ and RMSE\\(=8.69^{\\circ}\\ ISM slope estimates are concurrent with GLAS waveforms and can be used to correct biophysical parameters, such as tree height and biomass. They can also be fused with other DEMs, such as SRTM, to improve slope estimates.

  6. Influence of Different Slope Aspects on Some Soil Properties and Forest Soils Evolution (Case Study: Rostam Abad Region, Guilan Province

    Directory of Open Access Journals (Sweden)

    M. Zarinibahador

    2016-02-01

    Full Text Available Introduction: Spatial variation of soil properties is significantly influenced by numerous environmental factors such as landscape features, including position, topography, slope gradient and aspect, parent material, climate and vegetation. Soil properties vary spatially in south- and north-facing hill slopes. This factor (different slope aspects can affect the distribution of soil organic matter, the presence or absence of a layer, pH, nutrient levels, soil mineralogical and micromorphological properties. Topographic factors such as the orientation of the hill slope and the steepness of the slope affect microclimate, vegetation establishment, water movement and erosion. Aspect and slope control the movement of water and materials in a hill slope and contribute to differences in soil properties. Temperature, precipitation and climate vary with elevation and influence pedogenic processes. Accelerated rates of weathering and soil development were found to occur in soils on south-facing slopes. Slopes with a south aspect are dominated by stone and bare soil patches, while slopes with a north aspect are dominated by biotic components. Northern slopes have higher productivity and species diversity compared to Southern slopes. Slope aspect has a significant effect on the composition, species richness, structure and density of plant communities, differed significantly between North- and South- facing slopes. Materials and Methods: In the present study, the effects of two slope aspects on some soil properties and soil evolution was investigated in Northern Rostam Abad region in the Guilan Province. Five profiles in Southern hill slope(South-facing hill slopes and five profiles in Northern hill slopes(North-facing hill slopes with 40% slope and same parent material (basaltic andesite and same plant cover were dug. The elevation of two slope aspects was 240 meters from the sea level. Average annual temperatures and precipitation are16 degrees centigrade

  7. Slope of the Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope of slope was calculated from the bathymetry surface for each raster cell by applying the ArcGIS Spatial Analyst 'Slope' Tool to a previously created slope...

  8. Impact of disability and other physical health issues on academic outcomes among American Indian and Alaskan Native college students: an exploratory analysis.

    Science.gov (United States)

    Patterson Silver Wolf Adelv Unegv Waya, David A; Vanzile-Tamsen, Carol; Black, Jessica; Billiot, Shanondora M; Tovar, Molly

    2015-01-01

    This study investigated whether self-identified disabilities among American Indian and Alaskan Native college students impact academic performance and persistence to graduation and explored the differences in health and academic grades between American Indian and Alaskan Native students and students of other racial and ethnic identities using the National College Health Assessment. Findings indicate that American Indian or Alaskan Native students have significantly lower grades than White and Asian students, and American Indian and Alaskan Native women report the highest incidence of health problems of any demographic group. Exploratory results point to future research to determine the full impact of disabilities and poor health on academic success.

  9. Repertoire and classification of non-song calls in Southeast Alaskan humpback whales (Megaptera novaeangliae).

    Science.gov (United States)

    Fournet, Michelle E; Szabo, Andy; Mellinger, David K

    2015-01-01

    On low-latitude breeding grounds, humpback whales produce complex and highly stereotyped songs as well as a range of non-song sounds associated with breeding behaviors. While on their Southeast Alaskan foraging grounds, humpback whales produce a range of previously unclassified non-song vocalizations. This study investigates the vocal repertoire of Southeast Alaskan humpback whales from a sample of 299 non-song vocalizations collected over a 3-month period on foraging grounds in Frederick Sound, Southeast Alaska. Three classification systems were used, including aural spectrogram analysis, statistical cluster analysis, and discriminant function analysis, to describe and classify vocalizations. A hierarchical acoustic structure was identified; vocalizations were classified into 16 individual call types nested within four vocal classes. The combined classification method shows promise for identifying variability in call stereotypy between vocal groupings and is recommended for future classification of broad vocal repertoires.

  10. Water availability for winter wheat affected by summer fallow tillage practices in sloping dryland

    NARCIS (Netherlands)

    Wang, X.B.; Cai, D.X.; Jin, K.; Wu, H.J.; Bai, Z.G.; Zhang, C.J.; Yao, Y.Q.; Lu, J.J.; Wang, Y.H.; Yang, B.; Hartman, R.; Gabriels, D.

    2003-01-01

    The tillage experiments for winter wheat were conducted on the slope farmland in Luoyang,Henan Province in the semihumid to arid loess plateau areas of North China. Different tillage methods inclu-ding reduced tillage (RT), no-till (NT), 2 crops/year (2C), subsoiling(SS), and conventional tillage

  11. @iGlobigerina pachyderma@@ (Ehrenberg) in the shelf-slope sediments of northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A

    The occurrence of specimens of @iGlobigerina pachyderma@@ (Ehrenberg) which is considered to be a typical bipolar, cooler water species, in the Recent shelf-slope sediments of the northern Indian Ocean as far north as 9, 12, 14, 19 and 23...

  12. The Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    By overcoming the barriers that limit access to financial liquidity and human resource, the Sloping Land Conversion Program (SLCP) can promote rural livelihood diversification. This paper examines this effect using a household survey data set spanning the 1999 implementation of the Sloping land c...

  13. Lattice calculus of the morphological slope transform

    NARCIS (Netherlands)

    H.J.A.M. Heijmans (Henk); P. Maragos

    1995-01-01

    textabstractThis paper presents a study of the morphological slope transform in the complete lattice framework. It discusses in detail the interrelationships between the slope transform at one hand and the (Young-Fenchel) conjugate and Legendre transform, two well-known concepts from convex

  14. Internal waves and temperature fronts on slopes

    Directory of Open Access Journals (Sweden)

    S. A. Thorpe

    Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

    Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

  15. On the Pleistocene extinctions of Alaskan mammoths and horses

    OpenAIRE

    Solow, Andrew R.; Roberts, David L.; Robbirt, Karen M.

    2006-01-01

    The fossil record has been used to shed light on the late Pleistocene megafaunal extinctions in North America and elsewhere. It is therefore important to account for variability due to the incompleteness of the fossil record and error in dating fossil remains. Here, a joint confidence region for the extinction times of horses and mammoths in Alaska is constructed. The results suggest that a prior claim that the extinction of horses preceded the arrival of humans cannot be made with confidence.

  16. Clinical pathology and assessment of pathogen exposure in southern and Alaskan sea otters

    Science.gov (United States)

    Hanni, K.D.; Mazet, J.A.K.; Gulland, F.M.D.; Estes, James A.; Staedler, M.; Murray, M.J.; Miller, M.; Jessup, David A.

    2003-01-01

    The southern sea otter (Enhydra lutris nereis) population in California (USA) and the Alaskan sea otter (E. lutris kenyoni) population in the Aleutian Islands (USA) chain have recently declined. In order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 through 2000. Samples from 72 free-ranging Alaskan, 78 free-ranging southern, and (for pathogen exposure only) 41 debilitated southern sea otters in rehabilitation facilities were evaluated and compared to investigate regional differences. Serum chemistry and hematology values did not indicate a specific disease process as a cause for the declines. Statistically significant differences were found between free-ranging adult southern and Alaskan population mean serum levels of creatinine kinase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, calcium, cholesterol, creatinine, glucose, phosphorous, total bilirubin, blood urea nitrogen, and sodium. These were likely due to varying parasite loads, contaminant exposures, and physiologic or nutrition statuses. No free-ranging sea otters had signs of disease at capture, and prevalences of exposure to calicivirus, Brucella spp., and Leptospira spp. were low. The high prevalence (35%) of antibodies to Toxoplasma gondii in free-ranging southern sea otters, lack of antibodies to this parasite in Alaskan sea otters, and the pathogen's propensity to cause mortality in southern sea otters suggests that this parasite may be important to sea otter population dynamics in California but not in Alaska. The evidence for exposure to pathogens of public health importance (e.g., Leptospira spp., T. gondii) in the southern sea otter population, and the naïveté of both populations to other pathogens (e.g., morbillivirus

  17. Population decline in the Delta caribou herd with reference to other Alaskan herds

    Directory of Open Access Journals (Sweden)

    Patrick Valkenburg et al.

    1996-01-01

    Full Text Available After growing continuously for nearly 15 years, the Delta caribou herd began to decline in 1989. Most other Interior Alaskan herds also began declining. In the Delta herd, and in other herds, the declines were caused primarily by high summer mortality of calves and increased natural mortality of adult females. Other minor causes included increased winter mortality of calves, and reduced parturition rates of 3-year-old and older females. The decline in the Delta herd also coincided with increased wolf (Canis lupus numbers, winters with deeper than normal snow, and warm summers. Mean body weight of annual samples of 10-month-old female calves was consistently low during the decline. Except in some of the smallest Interior Alaskan herds, we conclude that evidence for population regulation in Alaskan caribou is weak, and that herds are likely to fluctuate within a wide range of densities due to complex interactions of predation and weather. Unless wolf numbers are influenced by man, the size of a caribou herd in a given year is likely to be largely a function of its size during the previous population low and the number of years of favorable weather in the interim.

  18. Trophic dynamics in marine nearshore systems of the Alaskan high arctic

    International Nuclear Information System (INIS)

    Dunton, K.H.

    1985-01-01

    This dissertation describes two ecological studies in the arctic Alaskan nearshore zone: the productivity and growth strategies of arctic kelp and the use of natural carbon isotope abundances to examine food web structure and energy flow in the marine ecosystem. Linear growth of the kelp, Laminaria solidungula is greatest in winter and early spring when nutrients are available for new tissue growth. Since over 90% of this growth occurs in complete darkness beneath a turbid ice canopy, the plant draws on stored food reserves and is in a carbon deficit during the ice covered period. Annual productivity of L. solidungula under these conditions is about 6 g C m -2 compared to about 10 g c m -2 if light penetrates the ice canopy. Carbon isotope abundances were used to assess food web structure and energy flow in the Boulder Patch, an isolated kelp bed community, and in the Alaskan Beaufort Sea fauna. Isotopic analyses of the resident fauna of the Boulder Patch revealed that kelp carbon contributes significantly to the diet of many benthic animals, including suspension feeders. Across the shelf of the Alaskan Beaufort Sea, a distinct gradient in the isotopic composition of marine zooplankton and benthic fauna was related to the intrusion of the Bering Sea water and upwelling in the eastern Beaufort Sea near Barter Island. The 13 C depletion in fauna of the eastern Beaufort Sea is presumed due to the cycling of 13 C depleted inorganic carbon into the euphotic zone

  19. Collapse of the northern Jalisco continental slope:Subduction erosion, forearc slivering, or subduction beneath the Tres Marias escarpment?

    Science.gov (United States)

    Bandy, W. L.; Mortera-Gutierrez, C. A.; Ortiz-Zamora, G.; Ortega-Ramirez, J.; Galindo Dominguez, R. E.; Ponce-Núñez, F.; Pérez-Calderón, D.; Rufino-Contreras, I.; Valle-Hernández, S.; Pérez-González, E.

    2010-12-01

    The Jalisco subduction zone exhibits several interesting characteristics. Among these is that convergence between the Rivera and North American plate is highly oblique, especially north of 20N, the obliquity progressively increasing to the NW. By analogy to other better studied subduction zones, this distribution of forces should produce a NW-SE extension in the overriding plate, especially north of 20N. This has led to the proposal that the trench perpendicular Bahia de Banderas is an expression of this extension [Kostoglodov and Bandy, JGR, vol. 100, 1995]. To further investigate this proposal, multibeam bathymetric data and seafloor backscatter images, seismic reflection sub-bottom profiles and marine magnetic data were collected during the MORTIC08 campaign of the B.O. EL PUMA in March 2009. The bathymetric data provides for 100% coverage (20 to 200 meter spacing of the actual measured depth value depending on the water depth) of the continental slope and trench areas north of 20N. These data indicate that a marked change occurs in the morphology of the continental slope at 20N. To the north the slope consists of a broad, fairly flat plain lying between a steep lower inner trench slope to the west and a steep, concave seaward, escarpment to the east. In contrast, to the south the continental slope exhibits a more gradual deepening until the steep lower inner trench slope. A prominent submarine canyon deeply incises the continental slope between these two morphotectonic domains. This canyon appears to represent the boundary between two NW-SE diverging forearc blocks or slivers, consistent with the presence of oblique convergence. In contrast, the broad, fairly flat plain is better explained by subsidence induced by subduction erosion (i.e. erosion of the base of the overriding plate underneath the continental slope area). The shoaling of the trench axis northward towards the Puerto Vallarta Graben and subsequent deepening may be related to subduction of the

  20. Evaluating the impacts of slope aspect on forest dynamic succession in Northwest China based on FAREAST model

    Science.gov (United States)

    Hu, Shanshan; Ma, Jianyong; Shugart, Herman H.; Yan, Xiaodong

    2018-03-01

    Mountain forests provide the main water resources and lumber for Northwest China. The understanding of the differences in forests growing among individual slope aspects in mountainous regions is of great significance to the wise management and planning of these natural systems. The aim of this study was to investigate the impacts of slope aspect on forest dynamic succession in Northwest China by using the dynamic forest succession model (FAREAST). First, the simulated forest composition and vertical forest zonation produced by the model were compared against recorded data in three sub-regions of the Altai Mountains. The FAREAST model accurately reproduced the vertical zonation, forest composition, growth curves of the dominant species (Larix sibirica), and forest biomass in the Altai Mountains. Transitions along the forest zones of the Altai Mountains averaged about a 400 m difference between the northern and southern sites. Biomass for forests on north-facing slopes were 11.0, 15.3 and 55.9 t C ha-1 higher than for south-facing slopes in the Northeast, Central and Southeast sub-regions, respectively. Second, our analyses showed that the FAREAST model can be used to predict dynamic forest succession in Northwest China under the influence of slope and aspect. In the Altai Mountains, the north-facing slopes supported the best forest growth, followed by the west- and east-facing slopes. South-facing slopes consistently exhibited the lowest growth, biomass storage and forest diversity.

  1. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic

    Science.gov (United States)

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  2. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic.

    Science.gov (United States)

    Gustine, David D; Brinkman, Todd J; Lindgren, Michael A; Schmidt, Jennifer I; Rupp, T Scott; Adams, Layne G

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (-21%) than the Central Arctic herd that wintered primarily in the arctic tundra (-11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  3. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic.

    Directory of Open Access Journals (Sweden)

    David D Gustine

    Full Text Available Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs, and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (-21% than the Central Arctic herd that wintered primarily in the arctic tundra (-11%. Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  4. Factors affecting seismic response of submarine slopes

    Directory of Open Access Journals (Sweden)

    G. Biscontin

    2006-01-01

    Full Text Available The response of submerged slopes on the continental shelf to seismic or storm loading has become an important element in the risk assessment for offshore structures and 'local' tsunami hazards worldwide. The geological profile of these slopes typically includes normally consolidated to lightly overconsolidated soft cohesive soils with layer thickness ranging from a few meters to hundreds of meters. The factor of safety obtained from pseudo-static analyses is not always a useful measure for evaluating the slope response, since values less than one do not necessarily imply slope failure with large movements of the soil mass. This paper addresses the relative importance of different factors affecting the response of submerged slopes during seismic loading. The analyses use a dynamic finite element code which includes a constitutive law describing the anisotropic stress-strain-strength behavior of normally consolidated to lightly overconsolidated clays. The model also incorporates anisotropic hardening to describe the effect of different shear strain and stress histories as well as bounding surface principles to provide realistic descriptions of the accumulation of the plastic strains and excess pore pressure during successive loading cycles. The paper presents results from parametric site response analyses on slope geometry and layering, soil material parameters, and input ground motion characteristics. The predicted maximum shear strains, permanent deformations, displacement time histories and maximum excess pore pressure development provide insight of slope performance during a seismic event.

  5. Wave run-up on sandbag slopes

    Directory of Open Access Journals (Sweden)

    Thamnoon Rasmeemasmuang

    2014-03-01

    Full Text Available On occasions, sandbag revetments are temporarily applied to armour sandy beaches from erosion. Nevertheless, an empirical formula to determine the wave run -up height on sandbag slopes has not been available heretofore. In this study a wave run-up formula which considers the roughness of slope surfaces is proposed for the case of sandbag slopes. A series of laboratory experiments on the wave run -up on smooth slopes and sandbag slopes were conducted in a regular-wave flume, leading to the finding of empirical parameters for the formula. The proposed empirical formula is applicable to wave steepness ranging from 0.01 to 0.14 and to the thickness of placed sandbags relative to the wave height ranging from 0.17 to 3.0. The study shows that the wave run-up height computed by the formula for the sandbag slopes is 26-40% lower than that computed by the formula for the smooth slopes.

  6. MECHANICAL HARVESTING OF COFFEE IN HIGH SLOPE

    Directory of Open Access Journals (Sweden)

    FELIPE SANTINATO

    2016-01-01

    Full Text Available Brazilian coffee farming is carried out both on flat and steep lands. In flat areas, mechanized operations are intensive; however, in steep slope areas, certain mechanized operations cannot be performed, such as harvesting. Based on this, the industry has developed machinery to harvest coffee in areas with up to 30% slope. However, harvesters have their efficiency and operational performance influenced by land slope. Thus, this study aimed to evaluate the operational performance and harvesting efficiency of a steep-slope harvester under different situations, using different speed settings. The experiment was carried out in the county of Santo Antônio do Amparo, state of Minas Gerais, Brazil, using five coffee stands with 10, 15, 20, 25 and 30% slope. Evaluations were performed with a self-propelled harvester (Electron, TDI®, Araguari, MG, Brazil at three rotation speeds (600, 800 and 1.000 rpm and two ground speeds (800 and 1.000 m h-1. The results showed the lower speed (800 m h-1 was suitable for 10% slope areas since the amount of fallen coffee berries. For areas of 20% slope, harvesting time was 21.6% longer than in flatter areas. Downtime varied from 10.66 to 29.18% total harvest due to a higher number of maneuvers.

  7. Contributions to knowledge of the continental margin of Uruguay. Uruguayan continental margin: morphology, geology and identification of the base of the slope

    International Nuclear Information System (INIS)

    Preciozzi, F.

    2014-01-01

    This work is about the morphology, geology and the identification of the base of the slope in the The Uruguayan continental margin which corresponds to the the type of divergent, volcanic and segmented margins. Morphologically is constituted by a clearly defined continental shelf, as well as a continental slope that presents configuration changes from north to south and passes directly to the abyssal plain

  8. Rock Slope Design Criteria : Executive Summary Report

    Science.gov (United States)

    2010-06-01

    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, and siltstones that...

  9. Slope activity in Gale crater, Mars

    Science.gov (United States)

    Dundas, Colin M.; McEwen, Alfred S.

    2015-01-01

    High-resolution repeat imaging of Aeolis Mons, the central mound in Gale crater, reveals active slope processes within tens of kilometers of the Curiosity rover. At one location near the base of northeastern Aeolis Mons, dozens of transient narrow lineae were observed, resembling features (Recurring Slope Lineae) that are potentially due to liquid water. However, the lineae faded and have not recurred in subsequent Mars years. Other small-scale slope activity is common, but has different spatial and temporal characteristics. We have not identified confirmed RSL, which Rummel et al. (Rummel, J.D. et al. [2014]. Astrobiology 14, 887–968) recommended be treated as potential special regions for planetary protection. Repeat images acquired as Curiosity approaches the base of Aeolis Mons could detect changes due to active slope processes, which could enable the rover to examine recently exposed material.

  10. Slope failure investigation management system : [research summary].

    Science.gov (United States)

    2013-03-01

    Highway slopes are exposed to a variety of environmental and climatic conditions, : such as deforestation, cycles of freezing and thawing weather, and heavy storms. : Over time, these climatic conditions, in combination with other factors such as : g...

  11. Percent Agricultural Land Cover on Steep Slopes

    Data.gov (United States)

    U.S. Environmental Protection Agency — Clearing land for agriculture tends to increase soil erosion. The amount of erosion is related to the steepness of the slope, farming methods used and soil type....

  12. Green technologies for reducing slope erosion.

    Science.gov (United States)

    2010-01-01

    As climate change alters precipitation patterns, departments of transportation will increasingly face the problem of : slope failures, which already cost California millions of dollars in repair work annually. Caltrans hopes to prevent : these failur...

  13. 3D geodetic monitoring slope deformations

    Directory of Open Access Journals (Sweden)

    Weiss Gabriel

    1996-06-01

    Full Text Available For plenty of slope failures that can be found in Slovakia is necessary and very important their geodetic monitoring (because of their activity, reactivisations, checks. The paper gives new methodologies for these works, using 3D terrestrial survey technologies for measurements in convenient deformation networks. The design of an optimal type of deformation model for various kinds of landslides and their exact processing with an efficient testing procedure to determine the kinematics of the slope deformations are presented too.

  14. Model slope infiltration experiments for shallow landslides early warning

    Science.gov (United States)

    Damiano, E.; Greco, R.; Guida, A.; Olivares, L.; Picarelli, L.

    2009-04-01

    simple empirical models [Versace et al., 2003] based on correlation between some features of rainfall records (cumulated height, duration, season etc.) and the correspondent observed landslides. Laboratory experiments on instrumented small scale slope models represent an effective way to provide data sets [Eckersley, 1990; Wang and Sassa, 2001] useful for building up more complex models of landslide triggering prediction. At the Geotechnical Laboratory of C.I.R.I.AM. an instrumented flume to investigate on the mechanics of landslides in unsaturated deposits of granular soils is available [Olivares et al. 2003; Damiano, 2004; Olivares et al., 2007]. In the flume a model slope is reconstituted by a moist-tamping technique and subjected to an artificial uniform rainfall since failure happens. The state of stress and strain of the slope is monitored during the entire test starting from the infiltration process since the early post-failure stage: the monitoring system is constituted by several mini-tensiometers placed at different locations and depths, to measure suction, mini-transducers to measure positive pore pressures, laser sensors, to measure settlements of the ground surface, and high definition video-cameras to obtain, through a software (PIV) appositely dedicated, the overall horizontal displacement field. Besides, TDR sensors, used with an innovative technique [Greco, 2006], allow to reconstruct the water content profile of soil along the entire thickness of the investigated deposit and to monitor its continuous changes during infiltration. In this paper a series of laboratory tests carried out on model slopes in granular pyroclastic soils taken in the mountainous area north-eastern of Napoli, are presented. The experimental results demonstrate the completeness of information provided by the various sensors installed. In particular, very useful information is given by the coupled measurements of soil water content by TDR and suction by tensiometers. Knowledge of

  15. Numerical Computation of Homogeneous Slope Stability

    Directory of Open Access Journals (Sweden)

    Shuangshuang Xiao

    2015-01-01

    Full Text Available To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM and particle swarm optimization algorithm (PSO to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759 were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS.

  16. Seasonal slope surface deformation measured with TLS

    International Nuclear Information System (INIS)

    Fan, L; Smethurst, J; Powrie, W; Sellaiya, A

    2014-01-01

    In temperate European climates, soil water removal due to vegetation transpiration peaks in summer and soil rewetting from higher levels of precipitation occurs in winter. In clays of high plasticity, the seasonal cycles of drying and wetting cause the soil to experience a volumetric change, resulting in seasonal shrinking and swelling. For a clay slope exhibiting volume change, such behaviour can lead to excessive deformation and could contribute to strain-softening and progressive slope failure. This can in turn cause traffic disruption and loss of life if roads and railways are founded on or surrounded by such slopes. This paper discusses the driving forces of seasonal surface movement, in particular the role of vegetation, and presents the use of Terrestrial Laser Scanning (TLS) to measure the surface movement of a lightly vegetated London Clay slope near Newbury, UK. Two TLS scans were carried out in early and late summer respectively, representing relative wet and dry conditions of the slope. Continuous field measurements of soil water content in upper layers of the slope were obtained from TDR ThetaProbes already installed at the site. The water content data are used to support the results obtained from TLS by indicating the likely volumetric change in the soil due to loss of water

  17. Automatic approach to deriving fuzzy slope positions

    Science.gov (United States)

    Zhu, Liang-Jun; Zhu, A.-Xing; Qin, Cheng-Zhi; Liu, Jun-Zhi

    2018-03-01

    Fuzzy characterization of slope positions is important for geographic modeling. Most of the existing fuzzy classification-based methods for fuzzy characterization require extensive user intervention in data preparation and parameter setting, which is tedious and time-consuming. This paper presents an automatic approach to overcoming these limitations in the prototype-based inference method for deriving fuzzy membership value (or similarity) to slope positions. The key contribution is a procedure for finding the typical locations and setting the fuzzy inference parameters for each slope position type. Instead of being determined totally by users in the prototype-based inference method, in the proposed approach the typical locations and fuzzy inference parameters for each slope position type are automatically determined by a rule set based on prior domain knowledge and the frequency distributions of topographic attributes. Furthermore, the preparation of topographic attributes (e.g., slope gradient, curvature, and relative position index) is automated, so the proposed automatic approach has only one necessary input, i.e., the gridded digital elevation model of the study area. All compute-intensive algorithms in the proposed approach were speeded up by parallel computing. Two study cases were provided to demonstrate that this approach can properly, conveniently and quickly derive the fuzzy slope positions.

  18. The oceanic base of slope record of the Permian-Triassic crisis: view from Tethys (Oman)

    OpenAIRE

    Marcoux, J.; Baud, A.; Richoz, S.

    2006-01-01

    The Oman Mountains provide some of the best sections of Permian and Triassic sediments from ocean sea floor to base-of-slope environments related to the distal South Tethyan margin. The central part of the range exposes the Buday'ah section of oceanic sediments in the so-called "Hawasina allochtons". The locality of Wadi Maqam in the north-western part of the Oman Mountains is among places where the thick Permian-Triassic base-of-slope sediments is exposed (Baud et al., 2001). Overlying 400 m...

  19. Drifter observations in the summer time Bay of Biscay slope current

    Science.gov (United States)

    Porter, M.; Inall, M. E.; Green, J. A. M.; Simpson, J. H.; Dale, A. C.; Miller, P. I.

    2016-05-01

    During the summer of 2012, 20 surface drifters drogued at 50 m depth were deployed on the continental slope to the north of the Bay of Biscay. Initially after release the drifters all crossed the slope, with 14 continuing equatorward, parallel to the slope following an absolute dynamic topography feature and 6 returning to the slope, in an eddy, visible in chlorophyll-a maps. Lagrangian statistics show an anisotropic flow field that becomes less tied to the absolute dynamic topography and increasingly dominated by diffusion and eddy processes. A weaker tie to the absolute dynamic topography allowed for total of 8 of the drifters crossed from the deep water onto the shelf, showing pathways for flow across the slope. A combination of drifter trajectories, absolute dynamic topography and chlorophyll-a concentration maps has been used to show that small anticyclonic eddies, tied to the complex slope topography provide a mechanism for on shelf transport. During the summer, the presence of these eddies can be seen in surface chlorophyll-a maps.

  20. Sloping fan travertine, Belen, New Mexico, USA

    Science.gov (United States)

    Cook, Megan; Chafetz, Henry S.

    2017-05-01

    Pliocene to Quaternary age travertines are very well-exposed in quarries near Belen, New Mexico, U.S.A., on the western edge of the Rio Grande Rift system. A series of hillside springs produced travertine tongues tens of meters thick and hundreds of meters long. The accumulations represent deposits from individual springs as well as the amalgamation of deposits. The overall architecture is predominantly composed of sloping fans with a smaller component of terrace mounds. The sloping fan deposits commonly have a dip of step morphology. As a consequence of vertical accretion in the pools, terrace mounds morphed into sloping fans. The travertine is composed of a variety of commonly reported constituents, i.e., centimeter thick laminae of bacterial shrubs and oncoids, foam rock, sheets and rafts, and finely crystalline crusts that occur throughout the sloping fan and terrace mound accumulations. Sheets and rafts formed as precipitates in pools on the surfaces of the fans and terraces as well as spelean deposits on the water surfaces of pools within cavities in the overall accumulation. Thus, the spelean rafts provide valuable indicators of original horizontality in the sloping fan strata. In addition, intraformational breccias, composed of locally torn-up travertine intraclastic boulders and deposited in with other travertine, and extraformational breccias, composed of torn-up travertine intraclasts mixed with siliciclastic fines and sand and Paleozoic limestone clasts transported downslope from higher on the hillside, are a common constituent in the sloping fan accumulation. The Belen travertines provide a very well-exposed example of sloping fan travertines and may provide relevant data with regard to the subsurface Aptian Pre-Salt deposits, offshore Brazil.

  1. The observed influence of local anthropogenic pollution on northern Alaskan cloud properties

    Science.gov (United States)

    Maahn, Maximilian; de Boer, Gijs; Creamean, Jessie M.; Feingold, Graham; McFarquhar, Greg M.; Wu, Wei; Mei, Fan

    2017-12-01

    Due to their importance for the radiation budget, liquid-containing clouds are a key component of the Arctic climate system. Depending on season, they can cool or warm the near-surface air. The radiative properties of these clouds depend strongly on cloud drop sizes, which are governed in part by the availability of cloud condensation nuclei. Here, we investigate how cloud drop sizes are modified in the presence of local emissions from industrial facilities at the North Slope of Alaska. For this, we use aircraft in situ observations of clouds and aerosols from the 5th Department of Energy Atmospheric Radiation Measurement (DOE ARM) Program's Airborne Carbon Measurements (ACME-V) campaign obtained in summer 2015. Comparison of observations from an area with petroleum extraction facilities (Oliktok Point) with data from a reference area relatively free of anthropogenic sources (Utqiaġvik/Barrow) represents an opportunity to quantify the impact of local industrial emissions on cloud properties. In the presence of local industrial emissions, the mean effective radii of cloud droplets are reduced from 12.2 to 9.4 µm, which leads to suppressed drizzle production and precipitation. At the same time, concentrations of refractory black carbon and condensation nuclei are enhanced below the clouds. These results demonstrate that the effects of anthropogenic pollution on local climate need to be considered when planning Arctic industrial infrastructure in a warming environment.

  2. NifH- Harboring Bacterial Community Composition Across an Alaskan Permafrost Thaw Gradient

    Directory of Open Access Journals (Sweden)

    Christopher Ryan Penton

    2016-11-01

    Full Text Available Since nitrogen (N is often limiting in permafrost soils, we investigated the N2-fixing genetic potential and the inferred taxa harboring those genes by sequencing nifH gene fragments in samples taken along a permafrost thaw gradient in an Alaskan boreal soil. Samples from minimally, moderately and extensively thawed sites were taken to a depth of 79 cm to encompass zones above and below the depth of the water table. NifH reads were translated with frameshift correction and 112,476 sequences were clustered at 5% amino acid dissimilarity resulting in 1,631 OTUs. Sample depth in relation to water table depth was correlated to differences in the NifH sequence classes. NifH sequences most closely related to group I nifH-harboring Alpha- and Beta Proteobacteria were in higher abundance above water table depth while those related to group III nifH-harboring Delta and Gamma Proteobacteria were more abundant below. The most dominant below water table depth NifH sequences, comprising 1/3 of the total, were distantly related to Verrucomicrobia-Opitutaceae. Overall, these results suggest that permafrost thaw alters the class-level composition of N2-fixing communities in the thawed soil layers and that this distinction corresponds to the depth of the water table. These nifH data were also compared to nifH sequences obtained from a study at an Alaskan taiga site, and to those of other geographically distant, non-permafrost sites. The two Alaska sites were differentiated largely by changes in relative abundances of the same OTUs, whereas the non-Alaska sites were differentiated by the lack of many Alaskan OTUs, and the presence of unique halophilic, sulfate- and iron-reducing taxa in the Alaska sites.

  3. Levoglucosan Levels in Alaskan Ice Cores as a Record of Past Wildfires

    Science.gov (United States)

    Dunham, M. E.; Osterberg, E. C.; Kehrwald, N. M.; Kennedy, J.; Ferris, D. G.

    2017-12-01

    Glaciers in southeast Alaska are significant contributors to global sea-level rise, and therefore understanding the mechanisms driving their recent mass loss is crucial for predicting future sea-level change. Fire activity in Alaska has increased dramatically during the last decade, adding a potential new source of light-absorbing organic material (soot) to the Juneau Icefield that can reduce albedo and enhance surface melt rates. The goal of this project is to create an accurate record of Alaskan wildfires to understand how Alaskan glacial mass balance is affected by the deposition of organic aerosols from wildfires. Previously, oxalate, ammonia, and potassium ion levels have been used as proxies for past wildfire activity, but these ions all have broader emission sources in addition to wildfires. Here we develop a record of past Alaskan fire events and climate from: (1) levels of a biomass burning indicator, levoglucosan, which only forms when cellulose is burned over 300 °C, (2) major ions including oxalate, ammonia, and potassium; (3) the number and size distribution of particles to quantify trace amounts of soot from wildfires; and (4) stable water isotope ratios as a proxy for past temperature in ice cores. We utilize a total of four shallow ice cores, ranging from 7 to 9 m in length, that were collected by a biogeochemistry team during the Juneau Icefield Research Program (JIRP) in 2016. Complications include our limited understanding of the conservation and degradation of levoglucosan over time or during the firnification process. We hypothesize that particle counts will be correlated with levoglucosan peaks, co-varying with wildfire frequency and temperatures over time. Based on previous work, we also expect to find correlations between levoglucosan and oxalate ion concentrations, even though oxalate ions have sources in addition to wildfire activity.

  4. Enhanced removal of Exxon Valdez spilled oil from Alaskan gravel by a microbial surfactant.

    Science.gov (United States)

    Harvey, S; Elashvili, I; Valdes, J J; Kamely, D; Chakrabarty, A M

    1990-03-01

    Remediation efforts for the oil spill from the Exxon Valdez tanker in Alaska have focused on the use of pressurized water at high temperature to remove oil from the beaches. We have tested a biological surfactant from Pseudomonas aeruginosa for its ability to remove oil from contaminated Alaskan gravel samples under various conditions, including concentration of the surfactant, time of contact, temperature of the wash, and presence or absence of xanthan gum. The results demonstrate the ability of the microbial surfactant to release oil to a significantly greater extent (2 to 3 times) than water alone, particularly at temperatures of 30 degrees C and above.

  5. Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)

    Energy Technology Data Exchange (ETDEWEB)

    Abhijit Dandekar; Shirish Patil; Santanu Khataniar

    2008-12-31

    Numerous early reports on experimental works relating to the role of wettability in various aspects of oil recovery have been published. Early examples of laboratory waterfloods show oil recovery increasing with increasing water-wetness. This result is consistent with the intuitive notion that strong wetting preference of the rock for water and associated strong capillary-imbibition forces gives the most efficient oil displacement. This report examines the effect of wettability on waterflooding and gasflooding processes respectively. Waterflood oil recoveries were examined for the dual cases of uniform and non-uniform wetting conditions. Based on the results of the literature review on effect of wettability and oil recovery, coreflooding experiments were designed to examine the effect of changing water chemistry (salinity) on residual oil saturation. Numerous corefloods were conducted on reservoir rock material from representative formations on the Alaska North Slope (ANS). The corefloods consisted of injecting water (reservoir water and ultra low-salinity ANS lake water) of different salinities in secondary as well as tertiary mode. Additionally, complete reservoir condition corefloods were also conducted using live oil. In all the tests, wettability indices, residual oil saturation, and oil recovery were measured. All results consistently lead to one conclusion; that is, a decrease in injection water salinity causes a reduction in residual oil saturation and a slight increase in water-wetness, both of which are comparable with literature observations. These observations have an intuitive appeal in that water easily imbibes into the core and displaces oil. Therefore, low-salinity waterfloods have the potential for improved oil recovery in the secondary recovery process, and ultra low-salinity ANS lake water is an attractive source of injection water or a source for diluting the high-salinity reservoir water. As part of the within-scope expansion of this project

  6. Decision Guide for Roof Slope Selection

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, T.R.

    1988-01-01

    This decision guide has been written for personnel who are responsible for the design, construction, and replacement of Air Force roofs. It provides the necessary information and analytical tools for making prudent and cost-effective decisions regarding the amount of slope to provide in various roofing situations. Because the expertise and experience of the decision makers will vary, the guide contains both basic slope-related concepts as well as more sophisticated technical data. This breadth of information enables the less experienced user to develop an understanding of roof slope issues before applying the more sophisticated analytical tools, while the experienced user can proceed directly to the technical sections. Although much of this guide is devoted to the analysis of costs, it is not a cost-estimating document. It does, however, provide the reader with the relative costs of a variety of roof slope options; and it shows how to determine the relative cost-effectiveness of different options. The selection of the proper roof slope coupled with good roof design, a quality installation, periodic inspection, and appropriate maintenance and repair will achieve the Air Force's objective of obtaining the best possible roofing value for its buildings.

  7. Role of slope on infiltration: A review

    Science.gov (United States)

    Morbidelli, Renato; Saltalippi, Carla; Flammini, Alessia; Govindaraju, Rao S.

    2018-02-01

    Partitioning of rainfall at the soil-atmosphere interface is important for both surface and subsurface hydrology, and influences many events of major hydrologic interest such as runoff generation, aquifer recharge, and transport of pollutants in surface waters as well as the vadose zone. This partitioning is achieved through the process of infiltration that has been widely investigated at the local scale, and more recently also at the field scale, by models that were designed for horizontal surfaces. However, infiltration, overland flows, and deep flows in most real situations are generated by rainfall over sloping surfaces that bring in additional effects. Therefore, existing models for local infiltration into homogeneous and layered soils and those as for field-scale infiltration, have to be adapted to account for the effects of surface slope. Various studies have investigated the role of surface slope on infiltration based on a theoretical formulations for the dynamics of infiltration, extensions of the Green-Ampt approach, and from laboratory and field experiments. However, conflicting results have been reported in the scientific literature on the role of surface slope on infiltration. We summarize the salient points from previous studies and provide plausible reasons for discrepancies in conclusions of previous authors, thus leading to a critical assessment of the current state of our understanding on this subject. We offer suggestions for future efforts to advance our knowledge of infiltration over sloping surfaces.

  8. Submarine Landslide Morphology of Box Slides Present on the Continental Slope Offshore Fraser Island, Queensland, Australia

    Science.gov (United States)

    Fletcher, M. J. A.; Hubble, T.; Clarke, S. L.; Airey, D.; Yu, P. W. C.

    2014-12-01

    The Fraser Island slide complex is located on eastern Australia's continental slope. Two potentially tsunamigenic submarine landslides identified here as the 'North Fraser Island Upper Slope Slide' (25km2 in area, 100m thick) and the 'Middle Fraser Island Middle Slope Slide' (12km2 in area, 50m thick) are described. Morphologic, sedimentologic and geomechanical properties for these slides are compared to data reported for existing submarine landslides located to the south in New South Wales (NSW). The two Fraser Island slides are translational, box-shaped, slab slides. We suspect that the slabs remained intact during downslope transport. The upper slope slide is situated at a water depth of approximately 750m at the northern end of the Fraser Canyon complex. The head of this slide has apparently detached from a structural surface comprised of a Miocene reef complex located beneath the continental shelf edge. The middle slope slide is situated on a large plateau to the south of the Fraser Canyon complex in 1500m of water. Cores taken in the continental slope within both slides are long and present hemipelagic muds. Cores taken adjacent to both slides are short and terminate in stiff muds of suspected Miocene or Pliocene age. Additionally, the core adjacent to the upper slope slide presents a near surface layer of upper-fining of coarse to fine shelly sand which we interpret to be a turbidite deposit. This layer was deposited above hemipelagic muds which are ubiquitously present on the upper eastern Australian continental slope in NSW and Southern Queensland.

  9. Stable Isotope Mapping of Alaskan Grasses and Marijuana

    Science.gov (United States)

    Booth, A. L.; Wooller, M. J.

    2008-12-01

    The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. δ13C, δ15N and δ18O values exhibit geographic patterns similar to the modern grasses, but carbon and nitrogen isotopes of some marijuana plants appear to be influenced by additional factors related to indoor growing conditions (supplementary CO2 sources and the application of organic fertilizer). As well as providing a potential forensic resource, our Poaceae isotope maps could serve additional value by providing resources for studying ecosystem nutrient cycling, for tracing natural ecological processes (i.e., animal migration and food web dynamics) and providing

  10. Centrifuge model test of rock slope failure caused by seismic excitation. Plane failure of dip slope

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Kawai, Tadashi

    2008-01-01

    Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is essential to evaluate more accurately the possibilities of rock slope failure and the potential failure boundary, which are triggered by earthquake ground motions. The purpose of this study is to analyze dynamic failure characteristics of rock slopes by centrifuge model tests for verification and improvement of the analytical methods. We conducted a centrifuge model test using a dip slope model with discontinuities limitated by Teflon sheets. The centrifugal acceleration was 50G, and the acceleration amplitude of input sin waves increased gradually at every step. The test results were compared with safety factors of the stability analysis based on the limit equilibrium concept. Resultant conclusions are mainly as follows: (1) The slope model collapsed when it was excited by the sine wave of 400gal, which was converted to real field scale, (2) Artificial discontinuities were considerably concerned in the collapse, and the type of collapse was plane failure, (3) From response acceleration records observed at the slope model, we can say that tension cracks were generated near the top of the slope model during excitation, and that might be cause of the collapse, (4) By considering generation of the tension cracks in the stability analysis, correspondence of the analytical results and the experimental results improved. From the obtained results, we need to consider progressive failure in evaluating earthquake induced rock slope failure. (author)

  11. Enzyme activity and microbial biomass availability in artificial soils on rock-cut slopes restored with outside soil spray seeding (OSSS): Influence of topography and season.

    Science.gov (United States)

    Zhang, Wenjuan; Ruirui, Li; Ai, Xiaoyan; Chen, Jiao; Xu, Wennian; Li, Wei; Ai, Yingwei

    2018-04-01

    Large-scale railway construction has resulted in large areas of bare-cut-slope, and outside soil spray seeding (OSSS), a frequently used technique, has been adopted for slope restoration for many years. However, compared with natural slope soils, the quality of artificial soils on rock-cut slopes is low. Enzyme activity and microbial biomass are the main indices used for estimating soil quality; thus, our objective was to explore the influence of slope position, slope aspect, and season on two important factors that positively influence the plant growth capability in artificial soil. Further, we suggest modifications of the proportions of OSSS ingredients, not only to manage cut slopes more economically but also to provide a new framework for managing desertification. We chose a bare-cut-slope that had been restored five years ago near the Suiyu Railway (Chongqing-Suining), in Sichuan Province, China, as our study plot. Soil samples were collected at a depth of 10 cm. We conclude that natural slopes exhibited higher urease, sucrase, and catalase activity and higher microbial biomass than cut slopes. The protease and polyphenoloxidase enzyme activities and the microbial biomass were higher on the cut slopes in the months of October and January, with the highest protease activity in October, and the highest polyphenoloxidase activity in January. The enzyme activity and microbial biomass were always lower on lower slopes, with the exception of polyphenoloxidase activity. The slope aspect influenced soil enzyme activity, resulting in higher activity on north-facing slopes than on south-facing slopes. These results provided scientific support for artificial revegetation methods in an ecological context. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Slope processes and related risk appearance within the Icelandic Westfjords during the twentieth century

    Directory of Open Access Journals (Sweden)

    A. Decaulne

    2005-01-01

    Full Text Available In North-western Iceland, records of slope processes were increasing during the twentieth century. Few dramatic events during the last decades highlighted the danger due to slope dynamics, leaving local populations in a risk situation that was merely unknown before 1970. The recent snow-avalanche, debris-flow and rock-fall activity underlined that the most frequent processes are not these with the largest human impact. In fact, the most catastrophic events were the extreme ones, following directly from a low frequency and a high magnitude. The purpose of this paper is to draw a parallel history of natural hazard and residence spatial extension, for an accurate understanding of the present-day risk situation, as the population growth markedly increased during the same time. Different quantitative and qualitative methods are applied. Geomorphological investigations locate the main threaten areas, in the path of slope processes release evidences, i.e. suitable slope morphology and/or inherited/actual forms. By a collection of dating data, as historic records and lichenometrical analysis, the frequency of given magnitude events is known. Climatic analysis clarifies the triggering meteorological conditions of slope processes and offers an overview of climate fluctuation during the investigated period; wind speed and direction is critical to hazardous snow-avalanche departure and snowmelt is crucial for debris-flow release. The findings clearly indicate that a combination of spatial expansion of inhabited areas and a lack of slope processes knowledge at the expansion time led to a recent and progressive risk appearance due to snow avalanches (including slush flows, debris flows and rock fall in most towns and villages of North-western Iceland.

  13. Establishing an Alaskan birch syrup industry: Birch Syrup—It’s the Un-maple!TM

    Science.gov (United States)

    Marlene. Cameron

    2001-01-01

    Ten years ago a small group of Alaskans began commercial production of birch syrup from the sap of the paper birch, Betula papyrifera, and established an industry that is expanding in response to demand and has the potential to make a significant contribution to Alaska's economy. There are still many problems to be solved; research and...

  14. Urban American Indian/Alaskan Natives Compared to Non-Indians in Out-of-Home Care

    Science.gov (United States)

    Carter, Vernon B.

    2011-01-01

    Historically, American Indian/Alaskan Native (AI/AN) children have been disproportionately represented in the foster care system. In this study, nationally representative child welfare data from October 1999 was used to compare urban AI/AN children to non-Indian children placed into out-of-home care. Compared to non-Indian children, urban AI/AN…

  15. Social Disruption and Psychological Stress in an Alaskan Fishing Community: The Impact of the Exxon Valdez Oil Spill.

    Science.gov (United States)

    Picou, J. Steven; And Others

    Technological accidents such as the Exxon Valdez oil spill in 1989 create man-made disaster situations that threaten community survival and the well-being and quality of life of community residents. This paper focuses on the social and psychological impact of the 1989 oil spill on Cordova, an isolated Alaskan community with high economic…

  16. Long-Term Effects of Otitis Media a Ten-Year Cohort Study of Alaskan Eskimo Children

    Science.gov (United States)

    Kaplan, Gary J.; And Others

    1973-01-01

    Histories of ear disease, otoscopic examinations, and audiologic, intelligence, and achievement tests were obtained from a cohort of 489 Alaskan Eskimo children, followed through the first 10 years of life, to determine whether otitis media (middle ear inflammation) deleteriously affected intellectual functioning and achievement in school.…

  17. Re-emergence of hereditary polyneuropathy in scandinavian alaskan malamute dogs-old enemy or new entity? A case series

    DEFF Research Database (Denmark)

    Jäderlund, Karin Hultin; Rohdin, Cecilia; Berendt, Mette

    2017-01-01

    A homozygous mutation has been identified in the N-myc downstream-regulated gene 1 (NDRG1) in recent cases of polyneuropathy in Alaskan malamute dogs from the Nordic countries and USA. The objective of the present study was to determine if cases diagnosed 30-40 years ago with polyneuropathy...

  18. TISSUE DISTRIBUTION OF PCBS AND ORGANOCHLORINE PESTICIDES IN ALASKAN NORTHERN FUR SEALS: COMPARISON OF VARIOUS CONGENER CLASSIFICATION SCHEMES

    Science.gov (United States)

    Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are believed to adversely affect reproduction and cause health problems in Pinnipeds 1-4. In this study, 145 PCB congeners and OCPs were analyzed in 10 juvenile male northern fur seals, Callorhinus ursinus, collected from Alaskan...

  19. Modern Slope Processes on the Moon

    Science.gov (United States)

    Shevchenko, V. V.; Pine, P. K.; Shevrel, S. D.; Dadu, I.; Lu, Y.; Skobeleva, T. P.; Kvaratskhelia, O.; Rosemberg, K.

    2012-01-01

    Slope movements of material in lunar craters are investigated based on remote spectral studies carried out on board the Clementine spacecraft, and data obtained during the large-scale survey on board the LRO (Lunar Reconnaissance Orbit) spacecraft. The morphological analysis of crater forms based on large-scale images and spectral and spectropolarized assessments of the exposition age (or maturity) of the slope material has led to the conclusion that the formation process of observed outcrops probably is a modern feature. The lower age limit of these structures is estimated at 40-80 years. Thus, slope movements of surface materials can continue at the present time, regardless of the age of the crater studied. Slope movements of crushed granular material lead to fresh outcrops of subsurface layers of marine or continental landscapes and, therefore, extend our capabilities to research the deep material of the Moon. To analyze this phenomenon, craters of 16 and 30 km have been selected. The length of fresh outcrops, while depending strongly on the dimensions of the craters, can be up to several kilometers. In connection with this, the prospect appears of remote analysis of rocks that came to the surface from depths of at least several hundred meters. In this case, there are openings for the contact analysis of subsurface material without the use of labor-intensive operations associated with the delivery of equipment for deep drilling to the lunar surface.

  20. Interrill soil erosion processes on steep slopes

    Science.gov (United States)

    To date interrill erosion processes and regimes are not fully understood. The objectives are to 1) identify the erosion regimes and limiting processes between detachment and transport on steep slopes, 2) characterize the interactive effects between rainfall intensity and flow depth on sediment trans...

  1. Mathematics, Physics and Computer Sciences Dual slope ...

    African Journals Online (AJOL)

    Mathematics, Physics and Computer Sciences Dual slope integration technique to design a digital thermometer. S. F. AKANDE, E. D. DADOEM. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/gjpas.v7i2.16256 · AJOL African Journals Online.

  2. VT USGS NED Slope (10 meter) - statewide

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Used ElevationDEM_DEM10M and the Arc/Info SLOPE command with the "PERCENT_RISE" and ".3048" Z_unit options to create this data layer. Input source...

  3. A Worthwhile Task to Teach Slope

    Science.gov (United States)

    Wagener, Lauren L.

    2009-01-01

    Since mathematics is found in every aspect of life, it is important for teachers to provide experiences that help students find connections and develop an appreciation for math and its use in their lives outside school. Slope is an excellent example of a math concept that is usually taught without context or connection. In this article, the…

  4. Fractal Rock Slope Dynamics Anticipating a Collapse

    Czech Academy of Sciences Publication Activity Database

    Paluš, Milan; Novotná, Dagmar; Zvelebil, Jiří

    2004-01-01

    Roč. 70 (2004), 036212 ISSN 1063-651X R&D Projects: GA ČR GA205/00/1055 Institutional research plan: CEZ:AV0Z1030915 Keywords : fractal * scaling * unstable rock slope * collapse prediction * engineering geology Subject RIV: BA - General Mathematics Impact factor: 2.352, year: 2004

  5. A Novel Way To Practice Slope.

    Science.gov (United States)

    Kennedy, Jane B.

    1997-01-01

    Presents examples of using a tic-tac-toe format to practice finding the slope and identifying parallel and perpendicular lines from various equation formats. Reports the successful use of this format as a review in both precalculus and calculus classes before students work with applications of analytic geometry. (JRH)

  6. Hill slope unsaturated flowpaths and soil moisture variability in a Forested Catchment in Southwest China

    OpenAIRE

    Sørbotten, Lars-Erik

    2011-01-01

    Forested catchments in subtropical southwest China are important sites for nitrogen, primarily due to denitrification. Denitrification depends strongly on soil moisture content and the residence time of soil water. Both depend on the hydrological properties of the soils. In this study we investigated the soil hydrological properties and water flow paths on a hill slope in the TieShanPing catchment around 25 kilometres north-east of Chongqing. Soils were sampled for analyses of water retention...

  7. Advance in prediction of soil slope instabilities

    Science.gov (United States)

    Sigarán-Loría, C.; Hack, R.; Nieuwenhuis, J. D.

    2012-04-01

    Six generic soils (clays and sands) were systematically modeled with plane-strain finite elements (FE) at varying heights and inclinations. A dataset was generated in order to develop predictive relations of soil slope instabilities, in terms of co-seismic displacements (u), under strong motions with a linear multiple regression. For simplicity, the seismic loads are monochromatic artificial sinusoidal functions at four frequencies: 1, 2, 4, and 6 Hz, and the slope failure criterion used corresponds to near 10% Cartesian shear strains along a continuous region comparable to a slip surface. The generated dataset comprises variables from the slope geometry and site conditions: height, H, inclination, i, shear wave velocity from the upper 30 m, vs30, site period, Ts; as well as the input strong motion: yield acceleration, ay (equal to peak ground acceleration, PGA in this research), frequency, f; and in some cases moment magnitude, M, and Arias intensity, Ia, assumed from empirical correlations. Different datasets or scenarios were created: "Magnitude-independent", "Magnitude-dependent", and "Soil-dependent", and the data was statistically explored and analyzed with varying mathematical forms. Qualitative relations show that the permanent deformations are highly related to the soil class for the clay slopes, but not for the sand slopes. Furthermore, the slope height does not constrain the variability in the co-seismic displacements. The input frequency decreases the variability of the co-seismic displacements for the "Magnitude-dependent" and "Soil-dependent" datasets. The empirical models were developed with two and three predictors. For the sands it was not possible because they could not satisfy the constrains from the statistical method. For the clays, the best models with the smallest errors coincided with the simple general form of multiple regression with three predictors (e.g. near 0.16 and 0.21 standard error, S.E. and 0.75 and 0.55 R2 for the "M

  8. Late nineteenth to early twenty-first century behavior of Alaskan glaciers as indicators of changing regional climate

    Science.gov (United States)

    Molnia, B.F.

    2007-01-01

    Alaska's climate is changing and one of the most significant indications of this change has been the late 19th to early 21st century behavior of Alaskan glaciers. Weather station temperature data document that air temperatures throughout Alaska have been increasing for many decades. Since the mid-20th century, the average change is an increase of ?????2.0????C. In order to determine the magnitude and pattern of response of glaciers to this regional climate change, a comprehensive analysis was made of the recent behavior of hundreds of glaciers located in the eleven Alaskan mountain ranges and three island areas that currently support glaciers. Data analyzed included maps, historical observations, thousands of ground-and-aerial photographs and satellite images, and vegetation proxy data. Results were synthesized to determine changes in length and area of individual glaciers. Alaskan ground photography dates from 1883, aerial photography dates from 1926, and satellite photography and imagery dates from the early 1960s. Unfortunately, very few Alaskan glaciers have any mass balance observations. In most areas analyzed, every glacier that descends below an elevation of ?????1500??m is currently thinning and/or retreating. Many glaciers have an uninterrupted history of continuous post-Little-Ice-Age retreat that spans more than 250??years. Others are characterized by multiple late 19th to early 21st century fluctuations. Today, retreating and/or thinning glaciers represent more than 98% of the glaciers examined. However, in the Coast Mountains, St. Elias Mountains, Chugach Mountains, and the Aleutian Range more than a dozen glaciers are currently advancing and thickening. Many currently advancing glaciers are or were formerly tidewater glaciers. Some of these glaciers have been expanding for more than two centuries. This presentation documents the post-Little-Ice-Age behavior and variability of the response of many Alaskan glaciers to changing regional climate. ?? 2006.

  9. Skate assemblage on the eastern Patagonian Shelf and Slope: structure, diversity and abundance.

    Science.gov (United States)

    Arkhipkin, A; Brickle, P; Laptikhovsky, V; Pompert, J; Winter, A

    2012-04-01

    The eastern Patagonian Shelf and continental slope of the south-west Atlantic Ocean support a high biodiversity and abundance of skates. In this study, meso-scale differences in the assemblages, spatial and seasonal distributions of skates are revealed among six habitat zones of the eastern Patagonian Shelf characterized by distinctive oceanographic conditions. Most skates belonged to temperate fauna, and their abundance was much greater in habitats occupied by temperate waters (north-western outer shelf) or mixed waters (northern slope) than in habitats occupied by sub-Antarctic waters (SASW) (south-eastern outer shelf and southern slope). Sub-Antarctic skates were not abundant on the shelf even in habitats occupied by SASW, occurring mainly in deep areas of the lower continental slope. The majority of temperate skates migrated seasonally, shifting northward in winter and spreading southward with warming waters in summer. Most temperate species had two peaks in female maturity (mainly spring and autumn) and spawned in the same habitats where they fed. It is hypothesized that the high biodiversity and abundance of skates on the Patagonian Shelf and Slope are due to the practical absence of their natural competitors, flatfishes, which occupy similar eco-niches elsewhere. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

  10. Sexual reproduction and seasonality of the Alaskan red tree coral, Primnoa pacifica.

    Science.gov (United States)

    Waller, Rhian G; Stone, Robert P; Johnstone, Julia; Mondragon, Jennifer

    2014-01-01

    The red tree coral Primnoa pacifica is an important habitat forming octocoral in North Pacific waters. Given the prominence of this species in shelf and upper slope areas of the Gulf of Alaska where fishing disturbance can be high, it may be able to sustain healthy populations through adaptive reproductive processes. This study was designed to test this hypothesis, examining reproductive mode, seasonality and fecundity in both undamaged and simulated damaged colonies over the course of 16 months using a deepwater-emerged population in Tracy Arm Fjord. Females within the population developed asynchronously, though males showed trends of synchronicity, with production of immature spermatocysts heightened in December/January and maturation of gametes in the fall months. Periodicity of individuals varied from a single year reproductive event to some individuals taking more than the 16 months sampled to produce viable gametes. Multiple stages of gametes occurred in polyps of the same colony during most sampling periods. Mean oocyte size ranged from 50 to 200 µm in any season, and maximum oocyte size (802 µm) suggests a lecithotrophic larva. No brooding larvae were found during this study, though unfertilized oocytes were found adhered to the outside of polyps, where they are presumably fertilized. This species demonstrated size-dependent reproduction, with gametes first forming in colonies over 42-cm length, and steady oocyte sizes being achieved after reaching 80-cm in length. The average fecundity was 86 (± 12) total oocytes per polyp, and 17 (± 12) potential per polyp fecundity. Sub-lethal injury by removing 21-40% of colony tissue had no significant reproductive response in males or females over the course of this study, except for a corresponding loss in overall colony fecundity. The reproductive patterns and long gamete generation times observed in this study indicate that recruitment events are likely to be highly sporadic in this species increasing its

  11. Sexual reproduction and seasonality of the Alaskan red tree coral, Primnoa pacifica.

    Directory of Open Access Journals (Sweden)

    Rhian G Waller

    Full Text Available The red tree coral Primnoa pacifica is an important habitat forming octocoral in North Pacific waters. Given the prominence of this species in shelf and upper slope areas of the Gulf of Alaska where fishing disturbance can be high, it may be able to sustain healthy populations through adaptive reproductive processes. This study was designed to test this hypothesis, examining reproductive mode, seasonality and fecundity in both undamaged and simulated damaged colonies over the course of 16 months using a deepwater-emerged population in Tracy Arm Fjord. Females within the population developed asynchronously, though males showed trends of synchronicity, with production of immature spermatocysts heightened in December/January and maturation of gametes in the fall months. Periodicity of individuals varied from a single year reproductive event to some individuals taking more than the 16 months sampled to produce viable gametes. Multiple stages of gametes occurred in polyps of the same colony during most sampling periods. Mean oocyte size ranged from 50 to 200 µm in any season, and maximum oocyte size (802 µm suggests a lecithotrophic larva. No brooding larvae were found during this study, though unfertilized oocytes were found adhered to the outside of polyps, where they are presumably fertilized. This species demonstrated size-dependent reproduction, with gametes first forming in colonies over 42-cm length, and steady oocyte sizes being achieved after reaching 80-cm in length. The average fecundity was 86 (± 12 total oocytes per polyp, and 17 (± 12 potential per polyp fecundity. Sub-lethal injury by removing 21-40% of colony tissue had no significant reproductive response in males or females over the course of this study, except for a corresponding loss in overall colony fecundity. The reproductive patterns and long gamete generation times observed in this study indicate that recruitment events are likely to be highly sporadic in this species

  12. Blood lead concentrations in Alaskan tundra swans: linking breeding and wintering areas with satellite telemetry

    Science.gov (United States)

    Ely, Craig R.; Franson, Christian

    2014-01-01

    Tundra swans (Cygnus columbianus) like many waterfowl species are susceptible to lead (Pb) poisoning, and Pb-induced mortality has been reported from many areas of their wintering range. Little is known however about Pb levels throughout the annual cycle of tundra swans, especially during summer when birds are on remote northern breeding areas where they are less likely to be exposed to anthropogenic sources of Pb. Our objective was to document summer Pb levels in tundra swans throughout their breeding range in Alaska to determine if there were population-specific differences in blood Pb concentrations that might pose a threat to swans and to humans that may consume them. We measured blood Pb concentrations in tundra swans at five locations in Alaska, representing birds that winter in both the Pacific Flyway and Atlantic Flyway. We also marked swans at each location with satellite transmitters and coded neck bands, to identify staging and wintering sites and determine if winter site use correlated with summer Pb concentrations. Blood Pb levels were generally low ( < 0.2 μg/ml) in swans across all breeding areas. Pb levels were lower in cygnets than adults, suggesting that swans were likely exposed to Pb on wintering areas or on return migration to Alaska, rather than on the summer breeding grounds. Blood Pb levels varied significantly across the five breeding areas, with highest concentrations in birds on the North Slope of Alaska (wintering in the Atlantic Flyway), and lowest in birds from the lower Alaska Peninsula that rarely migrate south for winter.

  13. The importance of inherited structures in slope evolution: the Ridnaun Valley case, Italy

    Science.gov (United States)

    Zorzi, L.; Flaim, L.; Massironi, M.; Genevois, R.; Stead, D.

    2013-12-01

    The south facing slope of the Ridnaun Valley (South Tyrol, Italy) comprises the crystalline units belonging to the Austoalpine Nappe of the Alpine orogenic wedge and shows evidence of quaternary gravitational evolution which is highly dependent on the interaction between the slope trend and the brittle/ductile structural setting. The slope valley is incised within the paragneiss rocks of the Oetztal - Stubei Unit and the micaschists of the Schneeberg Unit. These two units are separated by a NNW gentle dipping tectonic contact, which obliquely intersects the E-W slope, and is characterized by multiple ultracataclasitic layers that follow the regional low angle north-dipping schistosity. Folds with sub-horizontal E-trending axes induce a change in the dip direction of the regional schistosity from N dipping (unfavorable to the slip) to SE dipping (favorable to the slip). NNE-SSW and N-S trending faults, having a mean thickness of incoherent fault breccias of 1 m, affect the entire slope. These along with the folds and the ultracataclastic layers, have significant influence on rock mass mechanical properties and on mechanisms and timing of the observed gravitational phenomena. Field work and ALS-HRDEM analysis has revealed different gravitational movements along the slope. A fully evolved gravitational collapse, having the features of a Rock Avalanche (RA), characterizes the central part covering an area of about 2.4 km2; whereas to the east and west of the RA, deep seated gravitational slope deformations (DSGSDs) still affect the slope. An ongoing gravitational deformation is apparent in the uphill sections of the slope, next to the crown area of the RA. PS and DS - SAR interferometry data (provided by the Geological Survey of the Autonomous Province of Bolzano, Italy), testify an ongoing movement on both the DSGSDs bordering the RA, highlighting a most unstable area at the western sector. The heterogeneous behavior of the slope is most likely controlled by the

  14. The effects of slope length and slope gradient on the size distributions of loess slides: Field observations and simulations

    Science.gov (United States)

    Qiu, Haijun; Cui, Peng; Regmi, Amar Deep; Hu, Sheng; Wang, Xingang; Zhang, Yuzhu

    2018-01-01

    In this study, we characterize and consider the effects of slope length and slope gradient on the size distributions of loess slides. To carry out this study, we employ data on 275 loess slides within Zhidan County, Central Loess Plateau, China. These data were collected in the field and supplemented by the interpretation of remote sensing images. Both the field observations and slope stability analysis show that loess slide size increases with the slope length. Slide sizes is significantly correlated with slope length, showing a power law relationship in both cases. However, the simulation results show that slope gradient is not associated with loess slide size. The main part of the link between slope gradient and slide size seen in the observations is only apparent, as indicated by the strong connection between slope gradient and length. Statistical analysis of the field observations reveals that slope gradient decreases with increasing slope length, and this correlation interferes with the potential relationship between landslide sizes and slope gradient seen in the field observations. In addition, the probability densities of the areas of loess slides occurring on slopes of different slope lengths are determined using kernel density estimation. This analysis shows that slope length controls the rollover of the frequency-size distribution of loess slides. The scaling exponent increases with slope length.

  15. Slope parameters of ππ-system

    International Nuclear Information System (INIS)

    Isaev, P.S.; Osipov, A.A.

    1984-01-01

    The slope parameters of the ππ-system are calculated in the framework of the superconductor-tupe quark model. The analogous calculations are made for πK-system. The amplitudes are obtained by using the box quark diagrams and tree diagrams with the intermediate scalar epsilon(700), Ssup(x)(975), K tilde (1350) mesons and vector rho(770), K* (892) mesons

  16. Interrill soil erosion processes on steep slopes

    Science.gov (United States)

    Zhang, X. C. (John); Wang, Z. L.

    2017-05-01

    To date interrill erosion processes are not fully understood under different rainfall and soil conditions. The objectives are to 1) identify the interrill erosion regime and limiting process under the study condition, 2) characterize the interactive effects of rainfall intensity and flow depth on sediment transport competency and mode, and 3) develop a lumped interrill erosion model. A loess loam soil with 39% sand and 45% silt was packed to flumes and exposed to simulated rainfall. A complete factorial design with three factors was used, which included rainfall intensity (48, 62, 102, 149, and 170 mm h-1), slope gradient (17.6, 26.8, 36.4, 46.6, and 57.7%), and slope length (0.4, 0.8, 1.2, 1.6, and 2 m). Rain splash, sediment discharge in runoff, and flow velocity were measured. Results showed that rainfall intensity played a dual role not only in detaching soil materials but also in enhancing sediment transport. Sediment transport was the process limiting interrill erosion rate under the study condition. Two major sediment transport modes were identified: rainfall-driven rolling/creeping and flow-driven rolling/sliding. The relative importance of each mode was largely determined by flow depth. The competence of the flow in transporting sediment decreased downslope as flow depth increased due to increased dissipation of raindrop energy. The optimal mean flow depth for the maximal interrill erosion rates was erosion rate. The negative correlation seemed stronger for heavier rains, indicating the cushioning effects of flow depth. Lumped interrill erosion models, developed from short slopes, are likely to overestimate erosion rates. Given transport as the limiting process, the so called erodibility value, estimated with those models, is indeed sediment transportability under the study condition. The effects of slope length on interrill erosion regimes need to be studied further under a wider range of conditions.

  17. The sloping land conversion program in China

    DEFF Research Database (Denmark)

    Liu, Zhen; Lan, Jing

    2015-01-01

    Through addressing the motivations behind rural households’ livelihood diversification, this paper examines the effect of the Sloping Land Conversion Program (SLCP) on livelihood diversification using a longitudinal household survey data set spanning the overall implementation of the SLCP. Our...... results show that the SLCP works as a valid external policy intervention to increase rural livelihood diversification. In addition, the findings demonstrate that the implementation of the SLCP has had heterogeneous effects on livelihood diversification across different rural income groups. The lower...

  18. Ocean processes at the Antarctic continental slope.

    Science.gov (United States)

    Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker

    2014-07-13

    The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system.

  19. Slope and curvature of microbreaking wind waves

    Science.gov (United States)

    Caulliez, G.

    2009-04-01

    Microscale breaking is commonly observed at sea for steep waves less than 30 cm in wavelength. This phenomenon generates high surface slope and curvature roughness at the water surface, which has numerous implications for air-sea exchange and remote-sensing studies. In particular, microbreaking affects momentum transfer from wind to waves, leads to formation of vortices in water, and plays a key role in scattering of electromagnetic and acoustic waves by the air-sea interface. The geometric properties of the parasitic capillaries generated upon steep steady gravity-capillary waves have been well studied over the last decades, both experimentally and numerically. However, owing to their variability, the basic features of naturally occurring wind wave breakers as observed at sea or even in laboratory are far from being identified up to now. To this end, an experimental investigation of microbreaking wind waves was made in a large wind wave tank which combined visualizations of wave breaker profiles with single-point wave elevation and slope measurements. We show that microscale breakers exhibit a characteristic signature in slope and curvature suggesting formation of a bulge on the forward face of the wave crest. Parasitic ripples however are not necessarily generated ahead the bulge. Such breakers are observed for a wide range of wave steepness and wave slope skewness, their structure being only weakly dependent on wavelength and wind forcing. The geometric properties of microbreakers are analysed statistically and compared with the results of the recent numerical simulations by Hung and Tsai (J. Phys. Oceanogr., 2009).

  20. Transhumanism, medical technology and slippery slopes

    OpenAIRE

    McNamee, M J; Edwards, S D

    2006-01-01

    In this article, transhumanism is considered to be a quasi‐medical ideology that seeks to promote a variety of therapeutic and human‐enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed and on...

  1. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a...

  2. Modelling Progressive Failure in Rock-slopes

    Science.gov (United States)

    Pons, M. Güell I.; Jaboyedoff, M.

    2009-04-01

    Rock failures are common in Alpine mountain chains and pose a threat to life and infrastructures. In general, rock slope stability is an interplay between existing discontinuities and development of new ones in intact material. In this work, we study progressive failure by means of numerical methods at multiple scales and using distinct element methods (DEM). Distinct element methods are of advantage because they account for discontinuities and are able to simulate the development of failure in time. The use of micro-parameters instead of constitutive laws allows studying the influence of heterogeneities present in the rock mass. In the first case, the code PFC-2D is used at the slope scale to test the influence of the slope geometry, the joint sets distribution and the joint set persistence in the case of toppling failures under various triggering mechanisms. Heterogeneity properties (cohesion and friction angle) are distributed randomly to simulate natural rock variability. In the second case, a cellular automata model, which is based on concepts of progressive failure in disordered systems, is used to explain the role of heterogeneities in the fracture process at a small scale. The results provide a link to time-to-failure predictions observed in some field cases. This study aims to be a base for the development of a model which permits to understand why some rock masses accelerate until global failure while other are capable to stabilize under the same conditions.

  3. Progress in Predicting Rock-Slope Failures

    Science.gov (United States)

    Korup, O.

    2015-12-01

    Recent research on predicting landslides has seen a massive increase in statistical and computational methods that are largely adapted from the fields of machine learning and data mining. Judging from a sample of some 150 recent scientific papers, the gross majority of the reported success rates of these statistical methods are overwhelmingly high and promising at between 71% and 98%. Perhaps surprisingly, though, the death toll and damage from landslides has remained elevated in the early 21st century, so that reliably predicting the occurrence of rock-slope failures without overfitting our models remains challenging. Here I review some of the recent advances in this field, and show how novel results from landslide seismology and landslide sedimentology have promoted our ability of detecting large rock-slope failures in mountainous terrain. Several new detailed investigations of the internal nature of large rockslide deposits, for example, help to reduce the confusion potential with macroscopically similar moraine debris, or microscopically similar fault breccia. I further outline some of the limitations of empirical models that use rainfall intensity-duration thresholds for landslide early warning, and of multivariate methods concerned with mapping landslide susceptibility at the regional scale. I conclude by discussing the occurrence of 'black swans' such as long-runout rock-ice avalanches in size distributions of rock-slope failures, and their implications for quantitative hazard appraisals.

  4. Statistics of the slope-method estimator.

    Science.gov (United States)

    Rocadenbosch, F; Comerón, A; Albiol, L

    2000-11-20

    The slope method has customarily been used and is still used for inversion of atmospheric optical parameters, extinction, and backscatter in homogeneous atmospheres from lidar returns. Our aim is to study the underlying statistics of the old slope method and ultimately to compare its inversion performance with that of the present-day nonlinear least-squares solution (the so-called exponential-curve fitting). The contents are twofold: First, an analytical study is conducted to characterize the bias and the mean-square-estimation error of the regression operator, which permits estimation of the optical parameters from the logarithm of the range-compensated lidar return. Second, universal plots for most short- and far-range tropospheric backscatter lidars are presented as a rule of thumb for obtaining the optimum regression interval length that yields unbiased estimates. As a result, the simple graphic basis of the slope method is still maintained, and its inversion performance improves up to that of the present-day computer-oriented exponential-curve fitting, which ends the controversy between these two algorithms.

  5. Exercise-associated hyponatremia in Alaskan sled dogs: urinary and hormonal responses.

    Science.gov (United States)

    Hinchcliff, K W; Reinhart, G A; Burr, J R; Swenson, R A

    1997-09-01

    Exercise-associated hyponatremia occurs in horses and humans, both species that sweat, and in sled dogs, which do not sweat. To investigate the mechanism of exercise-associated hyponatremia in sled dogs, we measured water turnover, serum electrolyte concentrations and osmolality, plasma renal hormone concentrations, and urine composition of 12 fit Alaskan sled dogs before, during, and after a 490-km sled dog race (Ex group). Water turnover and serum electrolyte concentrations were measured in six similarly fit dogs that did not run (Sed group). Water turnover was significantly larger (P dogs (51 +/- 13 ml . kg-1 . day-1). There were significant (P dogs during the race. Plasma concentrations of arginine vasopressin decreased, whereas aldosterone and plasma renin activity increased significantly (P dogs.

  6. Identification of a haptoglobin-hemoglobin complex in the Alaskan Least Cisco (Coregonus sardinella).

    Science.gov (United States)

    Wahl, S M; Boger, J K; Michael, V; Duffy, L K

    1992-01-01

    The hemoglobin and a hemoglobin binding protein have been characterized in the Arctic fish (Coregonus sardinella). The evolutionary significance of the hemoglobin and plasma protein differences between fish and mammals is still unresolved. Blood samples from the Alaskan Least Cisco were separated into plasma and hemoglobin fractions and the proteins in these fractions were analyzed both by alkaline agarose gel electrophoresis, by isolelectric focusing, and by capillary electrophoresis. Staining the plasma proteins gels with o-dianisidine revealed hemoglobin containing protein complexes. A hemoglobin-containing band was observed in hemolyzed plasma which did not migrate with free hemoglobin, and is believed to be hemoglobin-haptoglobin complex. Size exclusion chromatography further characterized the hemoglobin as disassociating freely into dimers, and hemoglobin-haptoglobin complex having a molecular weight greater then 200,000 daltons.

  7. Google's Geo Education Outreach: Results and Discussion of Outreach Trip to Alaskan High Schools.

    Science.gov (United States)

    Kolb, E. J.; Bailey, J.; Bishop, A.; Cain, J.; Goddard, M.; Hurowitz, K.; Kennedy, K.; Ornduff, T.; Sfraga, M.; Wernecke, J.

    2008-12-01

    The focus of Google's Geo Education outreach efforts (http://www.google.com/educators/geo.html) is on helping primary, secondary, and post-secondary educators incorporate Google Earth and Sky, Google Maps, and SketchUp into their classroom lessons. In partnership with the University of Alaska, our Geo Education team members visited several remote Alaskan high schools during a one-week period in September. At each school, we led several 40-minute hands-on learning sessions in which Google products were used by the students to investigate local geologic and environmental processes. For the teachers, we provided several resources including follow-on lesson plans, example KML-based lessons, useful URL's, and website resources that multiple users can contribute to. This talk will highlight results of the trip and discuss how educators can access and use Google's Geo Education resources.

  8. Temporal pattern of skeletal muscle gene expression following endurance exercise in Alaskan sled dogs.

    Science.gov (United States)

    Brass, Eric P; Peters, Mette A; Hinchcliff, Kenneth W; He, Yudong D; Ulrich, Roger G

    2009-08-01

    Muscle responses to exercise are complex and include acute responses to exercise-induced injury, as well as longer term adaptive training responses. Using Alaskan sled dogs as an experimental model, changes in muscle gene expression were analyzed to test the hypotheses that important regulatory elements of the muscle's adaptation to exercise could be identified based on the temporal pattern of gene expression. Dogs were randomly assigned to undertake a 160-km run (n=9), or to remain at rest (n=4). Biceps femoris muscle was obtained from the unexercised dogs and two dogs at each of 2, 6, and 12 h after the exercise, and from three dogs 24 h after exercise. RNA was extracted and microarray analysis used to define gene transcriptional changes. The changes in gene expression after exercise occurred in a temporal pattern. Overall, 569, 469, 316, and 223 transcripts were differentially expressed at 2, 6, 12, and 24 h postexercise, respectively, compared with unexercised dogs (based on Por=1.5). Increases in a number of known transcriptional regulators, including peroxisome proliferator-activated receptor-alpha, cAMP-responsive element modulator, and CCAAT enhancer binding protein-delta, and potential signaling molecules, including brain-derived neurotrophic factor, dermokine, and suprabasin, were observed 2 h after exercise. Biological functional analysis suggested changes in expression of genes with known functional relationships, including genes involved in muscle remodeling and growth, intermediary metabolism, and immune regulation. Sustained endurance exercise by Alaskan sled dogs induces coordinated changes in gene expression with a clear temporal pattern. RNA expression profiling has the potential to identify novel regulatory mechanisms and responses to exercise stimuli.

  9. Impact of T1 slope on surgical and adjacent segment degeneration after Bryan cervical disc arthroplasty

    Directory of Open Access Journals (Sweden)

    Yang P

    2017-08-01

    Full Text Available Peng Yang,1 Yongqian Li,2,3 Jia Li,2,3,* Yong Shen2,3,* 1Department of Neurosurgery, Affiliated Hospital of North China University of Science and Technology, Tangshan, 2Department of Orthopedic Surgery, 3Key Laboratory of Orthopedic Biomechanics of Hebei Province, the Third Hospital of Hebei Medical University, Shijiazhuang, People’s Republic of China *These authors contributed equally to this work Background: This retrospective study investigated an association between preoperative T1 slope and surgical and adjacent segment degeneration (SASD after Bryan cervical disc arthroplasty (BCDA in patients with cervical degenerative disc disease.Methods: Based on preoperative standing lateral radiographs, 90 patients were classified according to T1 slope that was higher or lower than the 50th percentile (high T1 or low T1, 28 and 62 patients, respectively. Patients were also classified as SASD or non-SASD (38 and 52 patients, respectively determined by radiographs at final follow-up. Visual analog scale (VAS and Neck Disability Index (NDI scores for neck and arm pain were noted, and changes in the sagittal alignment of the cervical spine (SACS, functional spinal unit (FSU angle, and FSU range of motion (ROM were also noted. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for SASD.Results: The overall rate of SASD was 42.2% (38/90. The SACS, FSU angle, FSU ROM, and SASD rates of the high T1 and low T1 slope groups were significantly different at the last follow-up. The NDI and VAS scores of the high T1 slope group were significantly greater than those of the low T1 slope. The multivariate logistic regression analysis showed that high T1 slope and endplate coverage discrepancy (ie, residual space behind the prosthesis were significant risk factors for SASD after BCDA.Conclusion: High T1 slope and endplate coverage discrepancy were associated with SASD after BCDA. Patients with a high preoperative T1

  10. Slope stabilization guide for Minnesota local government engineers.

    Science.gov (United States)

    2017-06-01

    This user guide provides simple, costeffective methods for stabilizing locally maintained slopes along roadways in Minnesota. Eight slope stabilization techniques are presented that local government engineers can undertake using locally available ...

  11. Stabilization of erodible slopes with geofibers and nontraditional liquid additives.

    Science.gov (United States)

    2013-05-01

    Instability of erodible slopes due to extreme climate events and of permafrost slopes due degradation and thawing is a significant : engineering problem for northern transportation infrastructure. Engineers continually look for mitigation alternative...

  12. Wintertime slope winds and its turbulent characteristics in the Yeongdong region of Korea

    Science.gov (United States)

    Jeon, H. R.; Eun, S. H.; Kim, B. G.; Lee, Y. H.

    2015-12-01

    The Yeongdong region has various meteorological phenomenons by virtue of complicated geographical characteristics with high Taebaek Mountains running from the north to the south and an adjacent East Sea to the east. There are few studies on the slope winds and its turbulent characteristics over the complex terrain, which are critical information in mountain climbing, hiking, paragliding, even winter sports such as alpine skiing and ski jump etc. For the understanding of diverse mountain winds in the complex terrain in Yeongdong, hot-wire anemometers (Campbell Scientific) have been installed at a couple of sites since October 2014 and several automatic weather stations at several sites around the mountainous region in Yeongdong since November 2012.WRF model simulations have been also done with an ultra-fine horizontal resolution of 300 m for 10 years. Generally, model and observation show that the dominant wind is westerly, approximately more than 75%. It is quite consistent that wind fields from both model and observation agree with each other in the valley region and at the top of the mountain, but there is a significant disagreement in wind direction specifically in the slide slope. Probably this implies model's performance with even an ultra-fine resolution is still not enough for the slide slope domain of complex terrains. Despite that, the observation clearly showed up- and down slope winds for the weak synoptic conditions carefully selected such as strong insolation and a synoptic wind less than 5m/s in the 850 hPa. The up- and down slope flows are also demonstrated in the snow-covered condition as well as grass ground. Further, planar fit transformation algorithm against the coordinate tilt has been applied to raw wind data (10Hz) of the slope site for the analysis of turbulence properties. Turbulence also increases with synoptic wind strength. Detailed analysis of mechanical turbulence and buoyance will be discussed for different surface properties (grass

  13. Thermomechanical forcing of deep rock slope deformation: 1. Conceptual study of a simplified slope

    Science.gov (United States)

    Gischig, Valentin S.; Moore, Jeffrey R.; Evans, Keith F.; Amann, Florian; Loew, Simon

    2011-12-01

    Thermo-elastic rock slope deformation is often considered to be of relatively minor importance and limited to shallow depths subject to seasonal warming and cooling. In this study, we demonstrate how thermomechanical (TM) effects can drive rock slope deformation at greater depths below the annual thermal active layer. Here in Part 1 of two companion papers, we present 2D numerical models of a simplified slope subject to annual surface temperature cycles. The slope geometry and discontinuity sets are loosely based on the Randa instability considered in detail in Part 2. Results show that near-surface thermo-elastic stresses can propagate to depths of 100 m and more as a result of topography and elasticity of the rock mass. Shear dislocation along discontinuities can have both a reversible component controlled by discontinuity compliance and, provided that the stress state is sufficiently close to the strength limit, an irreversible component (i.e., slip). Induced slip increments are followed by stress redistribution resulting in the propagation of slip fronts. Thus, deformation and progressive rock slope failure can be driven solely by thermomechanical forcing. The influence of TM-induced stress changes becomes stronger for increasing numbers of critically stressed discontinuities and is enhanced if failure of discontinuities involves slip-weakening. The net TM effect acts as a meso-scale fatigue process, involving incremental discontinuity slip and hysteresis driven by periodic loading.

  14. Understanding slope behavior through microseismic monitoring

    Science.gov (United States)

    Arosio, Diego; Boccolari, Mauro; Longoni, Laura; Papini, Monica; Zanzi, Luigi

    2017-04-01

    It is well known that microseismic activity originates as an elastic stress wave at locations where the material is mechanically unstable. Monitoring techniques focusing on this phenomenon have been studied for over seventy years and are now employed in a wide range of applications. As far as the study of unstable slope is concerned, microseismic monitoring can provide real-time information about fracture formation, propagation and coalescence and may be an appropriate solution to reduce the risk for human settlements when structural mitigation interventions (e.g., rock fall nets and ditches) cannot cope with large rock volumes and high kinetic energies. In this work we present the datasets collected in a 4-year period with a microseismic monitoring network deployed on an unstable rock face in Northern Italy. We mainly focus on the classification and the interpretation of collected signals with the final aim of identifying microseismic events related to the kinematic and dynamic behavior of the slope. We have analyzed signal parameters both in time and frequency domains, spectrograms, polarization of 3-component recordings supported by principal component analysis. Clustering methodologies have been tested in order to develop an automatic classification routine capable to isolate a cluster with most of the events related to slope behavior and to discard all disturbances. The network features both geophones and meteorological sensors so that we could also explore the correlation between microseismic events and meteorological datasets, although no significant relationships emerged. On the contrary, it was found that the majority of the events collected by the network are short-time high-frequency signals generated by electromagnetic activity caused by near and far thunderstorms. Finally, we attempted a preliminary localization of the most promising events according to an oversimplified homogeneous velocity model to get a rough indication about the regions of the

  15. Western Ross Sea continental slope gravity currents

    Science.gov (United States)

    Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin

    2009-06-01

    Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ˜100 to ˜400 m on proceeding downslope from ˜600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ˜35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (-1.9 °C; 34.79) and approaching 1.5 m s -1 at descent angles as large as ˜60° relative to the isobaths. Such events were most common during November-May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real

  16. Transhumanism, medical technology and slippery slopes.

    Science.gov (United States)

    McNamee, M J; Edwards, S D

    2006-09-01

    In this article, transhumanism is considered to be a quasi-medical ideology that seeks to promote a variety of therapeutic and human-enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed and one particular criticism, moral arbitrariness, that undermines both weak and strong transhumanism is highlighted.

  17. Clustering Moving Objects Using Segments Slopes

    OpenAIRE

    Mohamed E. El-Sharkawi; Hoda M. O. Mokhtar; Omnia Ossama

    2011-01-01

    Given a set of moving object trajectories, we show how to cluster them using k-meansclustering approach. Our proposed clustering algorithm is competitive with the k-means clusteringbecause it specifies the value of “k” based on the segment’s slope of the moving object trajectories. Theadvantage of this approach is that it overcomes the known drawbacks of the k-means algorithm, namely,the dependence on the number of clusters (k), and the dependence on the initial choice of the clusters’centroi...

  18. Intertidal beach slope predictions compared to field data

    NARCIS (Netherlands)

    Madsen, A.J.; Plant, N.G.

    2001-01-01

    This paper presents a test of a very simple model for predicting beach slope changes. The model assumes that these changes are a function of both the incident wave conditions and the beach slope itself. Following other studies, we hypothesized that the beach slope evolves towards an equilibrium

  19. The continental slope current system between Cape Verde and the Canary Islands

    Directory of Open Access Journals (Sweden)

    Jesús Peña-Izquierdo

    2012-08-01

    Full Text Available We use hydrographic, velocity and drifter data from a cruise carried out in November 2008 to describe the continental slope current system in the upper thermocline (down to 600 m between Cape Verde and the Canary Islands. The major feature in the region is the Cape Verde Frontal Zone (CVFZ, separating waters from tropical (southern and subtropical (northern origin. The CVFZ is found to intersect the slope north of Cape Blanc, between 22°N and 23°N, but we find that southern waters are predominant over the slope as far north as 24°N. South of Cape Blanc (21.25°N the Poleward Undercurrent (PUC is a prominent northward jet (50 km wide, reaching down to 300 m and indistinguishable from the surface Mauritanian Current. North of Cape Blanc the upwelling front is found far offshore, opening a near-slope northward path to the PUC. Nevertheless, the northward PUC transport decreases from 2.8 Sv at 18°N to 1.7 Sv at 24°N, with about 1 Sv recirculating ofshore just south of Cape Blanc, in agreement with the trajectory of subsurface drifters. South of the CVFZ there is an abrupt thermohaline transition at σϴ=26.85 kg m–3, which indicates the lower limit of the relatively pure (low salt and high oxygen content South Atlantic Central Water (SACW variety that coexists with the dominant locally-diluted (salinity increases through mixing with North Atlantic Central Water but oxygen diminishes because of enhanced remineralization Cape Verde (SACWcv variety. At 16°N about 70% of the PUC transport corresponds to the SACW variety but but this is transformed into 40% SACWcv at 24°N. However, between Cape Verde and Cape Blanc and in the 26.85 < σϴ < 27.1 layer, we measure up to 0.8 Sv of SACWcv being transported south. The results strongly endorse the idea that the slope current system plays a major role in tropical-subtropical water-mass exchange.

  20. Utility of a Work Process Classification System for characterizing non-fatal injuries in the Alaskan commercial fishing industry

    Directory of Open Access Journals (Sweden)

    Laura N. Syron

    2016-01-01

    Full Text Available Background: The US commercial fishing industry is hazardous, as measured by mortality data. However, research on non-fatal injuries is limited. Non-fatal injuries constitute the majority of occupational injuries and can result in workers’ lowered productivity and wages, lost quality of life, and disability. In the United States, a Work Process Classification System (WPCS has previously been applied in Alaskan freezer-trawl and freezer-longline fleets to identify causes of injuries and specific hazards, but not to other fishing fleets. Objectives: This descriptive epidemiologic study aimed to explore the application and modification of the WPCS in multiple Alaskan fleets, characterize non-fatal occupational injuries in these fleets, and identify work processes that could be targeted for further investigation and future injury prevention efforts. Design: Traumatic, non-fatal injuries on-board Alaskan commercial fishing vessels were identified through United States Coast Guard investigative reports. Characteristics of injuries, as well as worker characteristics, were analysed. Injuries were coded using the WPCS. Results: We successfully utilized the WPCS to code non-fatal injury cases (n = 136. The most frequent main work processes associated with non-fatal injuries included: on-board trawlers, handling frozen fish and processing the catch; on-board vessels using pot/trap gear, handling the gear and shooting/setting the gear; on-board longliners, traffic on board and hauling the gear; and on-board processor vessels, processing the catch, other work with the catch, and handling frozen fish. Conclusions: The study confirmed that a WPCS can be applied to multiple Alaskan fleets to identify hazardous tasks. Hazards were unique for each vessel gear type. Future injury prevention efforts should target work processes associated with the most frequent and most severe injuries. Future studies should establish time estimates for work processes in order to

  1. Utility of a Work Process Classification System for characterizing non-fatal injuries in the Alaskan commercial fishing industry.

    Science.gov (United States)

    Syron, Laura N; Lucas, Devin L; Bovbjerg, Viktor E; Bethel, Jeffrey W; Kincl, Laurel D

    2016-01-01

    The US commercial fishing industry is hazardous, as measured by mortality data. However, research on non-fatal injuries is limited. Non-fatal injuries constitute the majority of occupational injuries and can result in workers' lowered productivity and wages, lost quality of life, and disability. In the United States, a Work Process Classification System (WPCS) has previously been applied in Alaskan freezer-trawl and freezer-longline fleets to identify causes of injuries and specific hazards, but not to other fishing fleets. This descriptive epidemiologic study aimed to explore the application and modification of the WPCS in multiple Alaskan fleets, characterize non-fatal occupational injuries in these fleets, and identify work processes that could be targeted for further investigation and future injury prevention efforts. Traumatic, non-fatal injuries on-board Alaskan commercial fishing vessels were identified through United States Coast Guard investigative reports. Characteristics of injuries, as well as worker characteristics, were analysed. Injuries were coded using the WPCS. We successfully utilized the WPCS to code non-fatal injury cases (n = 136). The most frequent main work processes associated with non-fatal injuries included: on-board trawlers, handling frozen fish and processing the catch; on-board vessels using pot/trap gear, handling the gear and shooting/setting the gear; on-board longliners, traffic on board and hauling the gear; and on-board processor vessels, processing the catch, other work with the catch, and handling frozen fish. The study confirmed that a WPCS can be applied to multiple Alaskan fleets to identify hazardous tasks. Hazards were unique for each vessel gear type. Future injury prevention efforts should target work processes associated with the most frequent and most severe injuries. Future studies should establish time estimates for work processes in order to determine risk estimates. Efforts to improve non-fatal injury reporting

  2. Isolation of a complete circular virus genome sequence from an Alaskan black-capped chickadee (Poecile atricapillus) gastrointestinal tract sample.

    Science.gov (United States)

    Hanna, Zachary R.; Runckel, Charles; Fuchs, Jerome; DeRisi, Joseph L.; Mindell, David P.; Van Hemert, Caroline R.; Handel, Colleen M.; Dumbacher, John P.

    2015-01-01

    We report here the genome sequence of a circular virus isolated from samples of an Alaskan black-capped chickadee (Poecile atricapillus) gastrointestinal tract. The genome is 2,152 bp in length and is most similar (30 to 44.5% amino acid identity) to the genome sequences of other single-stranded DNA (ssDNA) circular viruses belonging to the gemycircularvirus group.

  3. Seasonal changes in the major ion and δ13CDIC geochemistry of Arctic Alaskan rivers

    Science.gov (United States)

    Lehn, G. O.; Jacobson, A. D.; Douglas, T. A.; McClelland, J. W.; Khosh, M. S.; Barker, A.

    2010-12-01

    Model predications indicate anthropogenic greenhouse warming will be most severe at high latitudes where permafrost stores large quantities of organic carbon. Permafrost thaw could reintroduce this carbon into the carbon cycle and transform the Arctic into a source of CO2 and possibly, CH4. Thus, tracking the rate and extent of permafrost thaw bears on understanding feedbacks between Arctic climate change and global warming. Downward movement of the seasonally thawed “active” layer into previously frozen soils may yield unique mineral weathering signatures that relate to changes in carbon storage. We present two potential tracking methods, namely seasonal changes in dissolved major ion concentrations and the carbon isotope composition of dissolved inorganic carbon (δ13CDIC). We also present a novel method for measuring carbonate alkalinity in organic-rich rivers. Water samples were collected from six watersheds on the North Slope of Alaska. All rivers drain continuous permafrost but three drain tussock tundra-dominated watersheds and three drain bare bedrock catchments with minor tundra influences. Water samples were collected from April until October in 2009 and 2010. In organic-rich rivers, carbonate alkalinity and alkalinity associated with dissolved organic matter may contribute to total alkalinity. Carbonate alkalinity is difficult to measure at the low pH conditions common in organic-rich rivers. Moreover, conventional methods for measuring alkalinity, such as Gran titration, tend to overestimate total alkalinity, presumably because organic matter absorbs more protons than its functional charge equivalent. Thus, we measured dissolved CO2 in-situ using a customized NDIR sensor, and we calculated carbonate alkalinity using carbonate equilibria equations. Initial results suggest this method accurately characterizes the carbonate geochemistry of organic-rich rivers. Major ion and δ13CDIC trends suggest that silicate weathering dominates during the spring

  4. Characterizing organic matter lability in Alaskan tundra soils using mid-infrared spectroscopy

    Science.gov (United States)

    Fan, Z.; Matamala, R.; Jastrow, J. D.; Liang, C.; Calderon, F.; Michaelson, G. J.; Ping, C. L.; Mishra, U.; Hofmann, S. M.

    2015-12-01

    Soils in permafrost regions contain large amounts of soil organic carbon (SOC) that is preserved in a relatively undecomposed state due to cold and often wet conditions, yet the potential lability of these SOC stocks is still largely unknown. Traditional methods of assessing SOC lability (e.g., laboratory incubation studies) are labor intensive and time consuming. Fourier-transform mid-infrared spectroscopy (MidIR) provides a means to quickly estimate SOC quantity and quality based on the wealth of spectral information. In this study, we explored the possibility of linking MidIR spectra with SOC lability in Arctic tundra soils. Soils from four sites on the North Slope of Alaska were used in this study: a wet non-acidic tundra site in the coastal plain (CP), two moist acidic tundra sites between the northern foothills and the coastal plain (HC and SH), and another moist acidic tundra site in the northern foothills (HV). Active-layer organic and mineral soils and upper permafrost soils from the four sites were incubated for 60 days at -1, 1, 4, 8 and 16 °C. Thawed soils were allowed to drain to field capacity. Carbon dioxide (CO2) production was measured throughout the study. The chemical composition (e.g., total organic carbon and nitrogen) and MidIR spectra of soil samples were obtained before and after the incubations. CO2 production varied among soils and temperatures. CO2 production was greatest at 16 °C for CP and SH organic layers and for HC and HV permafrost layers. These trends among soil layers and sites remained similar at all temperatures. We found a good correlation between MidIR and cumulative 60-day CO2 production across different soils and temperatures. Characteristic MidIR bands and band ratios previously identified in the literature were also correlated with total CO2 production. For example, several band ratios (such as the ratio of aliphatics to clay or the ratio of lignin or phenolics to minerals) in the mineral active layer were highly

  5. Impact of underground mining to slope deformation genesis at Doubrava Ujala

    Directory of Open Access Journals (Sweden)

    Marian Marschalko

    2009-12-01

    Full Text Available The study deals with the evaluation of possible impact of undermining on a slope deformation Doubrava Ujala nearby the cityof Karviná in the north-east of the Czech Republic. Undermining is a phenomenon caused by underground mining of black coalin the active Karviná part of the Ostrava-Karviná District. It is on the boundary of the working districts Karviná – Mines I and Poruba,which are operated by the Karviná Mine. In order to assess the possible impact, isocatabase maps in different time sections were useddocumenting the chronology of the subsidence trough formation and next, ground deformation parameters. The activity of slopemovement was registered by means of zone extensometry on the surface and in the depth by means of precise inclinometry measuring.Apart from the impact of undermining, the effects of climatic conditions were taken into consideration, correlating the movement sizewith precipitation depth in the nearest rainfall gauging stations. As for the mechanism of undermining impact there is an apparentinfluence of additional stress from undermining caused by elongation of the ground surface, which is evidenced by the positionof the slope deformation in the convex part of the subsidence trough slope. All the above mentioned factors influence the stabilityconditions of the slope deformation.

  6. Frozen debris lobes, permafrost slope instability, and a potential infrastructure hazard in the south-central Brooks Range of Alaska

    Science.gov (United States)

    Daanen, R. P.; Darrow, M.; Grosse, G.; Jones, B. M.

    2012-12-01

    Dalton highway, through contact or aluviation and as a result will affect maintenance of the Trans Alaskan Pipeline. Current research aims to better understand frozen debris lobes, but future climate change may also affect slopes that are currently stable, but also contain warming permafrost sediments.;

  7. Age of the Mars Global Northerly Slope: Evidence From Utopia Planitia

    Science.gov (United States)

    McGill, George E.

    2002-01-01

    Recent results from the Mars Orbiter Laser Altimeter (MOLA) experiment on Mars Global Surveyor (MGS) indicate that most of Mars is characterized by a very gentle, roughly northerly slope. Detailed mapping in north-central Arabia Terra combined with superposition relations and crater counts indicate that, in that region at least, this northerly slope must have been formed no later than Late Hesperian, with the most likely time of formation being Late Hesperian. Current research in Utopia Planitia intended as a test of extant models for the formation of giant polygons has turned up good evidence for a Late Hesperian age for the northerly tilt in this region as well, as will be discussed.

  8. Multi-year Current Observations on the Shelf Slope off Cape Hatteras, NC

    Science.gov (United States)

    Muglia, M.

    2017-12-01

    As part of an observing and modeling effort by the North Carolina Renewable Ocean Energy Program to determine if the Gulf Stream is a viable marine hydrokinetic energy resource for the state, upper continental slope current measurements were made over a period of nearly four years off of Cape Hatteras, NC. Velocity profiles were measured by a near-bottom, upward-looking, 150-kHz Acoustic Doppler Current Profiler deployed at a depth of 230-260 m. The mooring was sited at the location where water from the Gulf Stream, Middle Atlantic Bight, South Atlantic Bight, and Slope Sea all converge. Measured tidal amplitudes here are 2 m. These observations are used to consider the temporal variability and vertical structure of the currents at this location at tidal to interannual periods at this complex location. Concurrent near-bottom water mass properties are considered.

  9. Assessment and mapping of slope stability based on slope units: A ...

    Indian Academy of Sciences (India)

    4) 1153–1171. Muntohar A S and Liao H J 2010 Rainfall infiltration: Infi- nite slope model for landslides triggering by rainstorm;. Nat. Hazards 54(3) 967–984. Muthu K, Petrou M, Tarantino C and Blonda P 2008 Land- slide possibility mapping ...

  10. Effects of slope gradient on hydro-erosional processes on an aeolian sand-covered loess slope under simulated rainfall

    Science.gov (United States)

    Zhang, F. B.; Yang, M. Y.; Li, B. B.; Li, Z. B.; Shi, W. Y.

    2017-10-01

    The aeolian sand-covered loess slope of the Wind-Water Erosion Crisscross Region of the Loess Plateau in China may play a key role in contributing excessive sediment to the Yellow River. Understanding its hydro-erosional processes is crucial to assessing, controlling and predicting soil and water losses in this region and maintaining the ecological sustainability of the Yellow River. Simulated rainfall (intensity 90 mm h-1) was used to investigate the runoff and soil loss from loess slopes with different slope gradients (18%, 27%, 36%, 47%, and 58%) and overlying sand layer thicknesses (0, 5 and 10 cm). As compared with uncovered loess slopes, an overlying sand layer delayed runoff production, reduced cumulative runoff and increased cumulative soil loss, as well as enhancing variations among slope gradients. Cumulative runoff and soil loss from the sand-covered loess slopes increased with increasing slope gradients and then slightly decreased, with a peak at about 47% gradient; they both were greater from the 10-cm sand-covered loess slope than from the 5-cm except for with 18% slope gradient. In general, differences in cumulative runoff between sand layer thicknesses became smaller, while those in cumulative soil loss became larger, with increasing slope gradient. Runoff and soil loss rates on the sand-covered loess slopes exhibited unimodal distributions during the rainstorms. Maximum values tended to occur at the same rain duration, and increased considerably with increasing slope gradient and sand layer thickness on slopes that were less than 47%. Liquefaction process might occur on the lower loess slopes covered with thinner sand layers but failures similar to shallow landslides might occur when the sand layer was thicker on steeper slopes. The presence of an overlying sand layer changed the relationship between runoff and soil loss rates during intense rainstorms and this change varied with different slope gradients. Our results demonstrated that the effects

  11. The gas century: worldwide LNG developments may deal death blow to Alaskan pipeline dream

    International Nuclear Information System (INIS)

    Lorenz, A.

    2004-01-01

    The growing interest in liquefied natural gas (LNG), which casts doubt on the viability of the Alaska gas pipeline, and the potential impacts on Canadian gas exports to the United States are discussed. There is currently a proposal before Congress for an Alaskan LNG project, and consensus appears to be building among American energy experts and law-makers that building a multitude of LNG facilities would be more flexible and cheaper than building the proposed Alaska pipeline. As further proof of the growing popularity of LNG, U.S. industry lobbyists are said to be rapidly gaining congressional support for the idea of building eight to ten billion cubic feet per day of LNG capacity along the U. S. coast. Either development, -- LNG facilities or the Alaska pipeline -- have the potential to seriously impact Canadian natural gas exports. If the Alaska pipeline is built, the addition of five billion cubic feet per day of new gas on the market would cause gas prices to fall; if the U.S. decides to subsidize its gas industry, Canadian gas would be put at a serious disadvantage. Conversely, if the Alaskan LNG proposal were to succeed, the potential demise of the Alaska pipeline would mean the loss of about 12,000 jobs that would be created during the Canadian construction phase of the pipeline, as well as the loss of tariffs. Industry experts predict that by 2005 LNG terminals will dot the periphery of the U. S. coast line; to prepare for these eventualities, Canadian companies, such as Irving Oil, TransCanada Pipelines and EnCana are taking note, and are scrambling not to be left out of the game. As proof of the seriousness of their concern, Irving Oil is adding a Can$500 million LNG facility to its Canaport terminal on the Scotian shelf; TCPL is working to supply an LNG terminal offshore Massachusetts, and EnCana is refurbishing a Louisiana salt cavern to prepare for storage of gas delivered to the Gulf Coast

  12. On the Frontline: Tracking Ocean Acidification in an Alaskan Shellfish Hatchery

    Science.gov (United States)

    Evans, Wiley; Mathis, Jeremy T.; Ramsay, Jacqueline; Hetrick, Jeff

    2015-01-01

    The invasion of anthropogenic carbon dioxide (CO2) into the ocean is shifting the marine carbonate system such that saturation states of calcium carbonate (CaCO3) minerals are decreasing, and this is having a detrimental impact on early life stages of select shellfish species. The global, secular decrease in CaCO3 saturation states is occurring on top of a backdrop of large natural variability in coastal settings; progressively shifting the envelope of variability and leading to longer and more frequent exposure to adverse conditions. This is a great concern in the State of Alaska, a high-latitude setting vulnerable to rapid changes in the marine carbonate system, where an emerging shellfish industry plans major growth over the coming decades. Currently, the Alutiiq Pride Shellfish Hatchery (APSH) in Seward, Alaska is the only hatchery in the state, and produces many shellfish species with early life stages known to be sensitive to low CaCO3 saturation states. Here we present the first land-based OA measurements made in an Alaskan shellfish hatchery, and detail the trends in the saturation state of aragonite (Ωarag), the more soluble form of CaCO3, over a 10-month period in the APSH seawater supply. These data indicate the largest changes are on the seasonal time scale, with extended periods of sub-optimal Ωarag levels (Ωarag < 1.5) in winter and autumn associated with elevated water column respiration and short-lived runoff events, respectively. The data pinpoint a 5-month window of reprieve with favorable Ωarag conditions above the sub-optimal Ωarag threshold, which under predicted upper-bound CO2 emissions trajectories is estimated to close by 2040. To date, many species in production at APSH remain untested in their response to OA, and the data presented here establish the current conditions at APSH as well as provide a framework for hatchery-based measurements in Alaska. The current and expected conditions seen at APSH are essential to consider for this

  13. On the Frontline: Tracking Ocean Acidification in an Alaskan Shellfish Hatchery.

    Directory of Open Access Journals (Sweden)

    Wiley Evans

    Full Text Available The invasion of anthropogenic carbon dioxide (CO2 into the ocean is shifting the marine carbonate system such that saturation states of calcium carbonate (CaCO3 minerals are decreasing, and this is having a detrimental impact on early life stages of select shellfish species. The global, secular decrease in CaCO3 saturation states is occurring on top of a backdrop of large natural variability in coastal settings; progressively shifting the envelope of variability and leading to longer and more frequent exposure to adverse conditions. This is a great concern in the State of Alaska, a high-latitude setting vulnerable to rapid changes in the marine carbonate system, where an emerging shellfish industry plans major growth over the coming decades. Currently, the Alutiiq Pride Shellfish Hatchery (APSH in Seward, Alaska is the only hatchery in the state, and produces many shellfish species with early life stages known to be sensitive to low CaCO3 saturation states. Here we present the first land-based OA measurements made in an Alaskan shellfish hatchery, and detail the trends in the saturation state of aragonite (Ωarag, the more soluble form of CaCO3, over a 10-month period in the APSH seawater supply. These data indicate the largest changes are on the seasonal time scale, with extended periods of sub-optimal Ωarag levels (Ωarag < 1.5 in winter and autumn associated with elevated water column respiration and short-lived runoff events, respectively. The data pinpoint a 5-month window of reprieve with favorable Ωarag conditions above the sub-optimal Ωarag threshold, which under predicted upper-bound CO2 emissions trajectories is estimated to close by 2040. To date, many species in production at APSH remain untested in their response to OA, and the data presented here establish the current conditions at APSH as well as provide a framework for hatchery-based measurements in Alaska. The current and expected conditions seen at APSH are essential to

  14. Methodologies for risk analysis in slope instability

    International Nuclear Information System (INIS)

    Bernabeu Garcia, M.; Diaz Torres, J. A.

    2014-01-01

    This paper is an approach to the different methodologies used in conducting landslide risk maps so that the reader can get a basic knowledge about how to proceed in its development. The landslide hazard maps are increasingly demanded by governments. This is because due to climate change, deforestation and the pressure exerted by the growth of urban centers, damage caused by natural phenomena is increasing each year, making this area of work a field of study with increasing importance. To explain the process of mapping a journey through each of the phases of which it is composed is made: from the study of the types of slope movements and the necessary management of geographic information systems (GIS) inventories and landslide susceptibility analysis, threat, vulnerability and risk. (Author)

  15. Positive Surge Propagation in Sloping Channels

    Directory of Open Access Journals (Sweden)

    Daniele Pietro Viero

    2017-07-01

    Full Text Available A simplified model for the upstream propagation of a positive surge in a sloping, rectangular channel is presented. The model is based on the assumptions of a flat water surface and negligible energy dissipation downstream of the surge, which is generated by the instantaneous closure of a downstream gate. Under these hypotheses, a set of equations that depends only on time accurately describes the surge wave propagation. When the Froude number of the incoming flow is relatively small, an approximate analytical solution is also proposed. The predictive ability of the model is validated by comparing the model results with the results of an experimental investigation and with the results of a numerical model that solves the full shallow water equations.

  16. Development of kenaf mat for slope stabilization

    Science.gov (United States)

    Ahmad, M. M.; Manaf, M. B. H. Ab; Zainol, N. Z.

    2017-09-01

    This study focusing on the ability of kenaf mat to act as reinforcement to laterite compared to the conventional geosynthetic in term of stabilizing the slope. Kenaf mat specimens studied in this paper are made up from natural kenaf fiber with 3mm thickness, 150mm length and 20mm width. With the same size of specimens, geosynthetic that obtain from the industry are being tested for both direct shear and tensile tests. Plasticity index of the soil sample used is equal to 13 which indicate that the soil is slightly plastic. Result shows that the friction angle of kenaf mat is higher compared to friction between soil particles itself. In term of resistance to tensile load, the tensile strength of kenaf mat is 0.033N/mm2 which is lower than the tensile strength of geosynthetic.

  17. ASPECTS OF DRIP IRRIGATION ON SLOPES

    Directory of Open Access Journals (Sweden)

    Oprea Radu

    2010-01-01

    Full Text Available Nowadays, water and its supply raise problems of strategic importance, of great complexity, being considered one of the keys to sustainable human development. Drip irrigation consists in the slow and controlled administration of water in the area of the root system of the plants for the purposes of fulfilling their physiological needs and is considered to be one of the variants of localized irrigation. Water is distributed in a uniform and slow manner, drop by drop, in a quantity and with a frequency that depend on the needs of the plant, thanks to the exact regulation of the water flow rate and pressure, as well as to the activation of the irrigation based on the information recorded by the tensiometer with regard to soil humidity. This method enables the exact dosage of the water quantity necessary in the various evolution stages of the plant, thus eliminating losses. By applying the irrigation with 5 liters of water per linear meter, at a 7 days interval, in the month of august, for a vine cultivated on a slope, in layers covered with black film and irrigated via dropping, soil humidity immediately after irrigation reaches its highest level, but within the limits of active humidity, on the line of the irrigation band. Three days later, the water content of the soil in the layer is relatively uniform, and, after this interval, it is higher in the points situated at the basis of the film. This technology of cultivation on slopes favors the accumulation, in the soil, of the water resulted from heavy rains and reduces soil losses as a result of erosion.

  18. An alternative soil nailing system for slope stabilization: Akarpiles

    Science.gov (United States)

    Lim, Chun-Lan; Chan, Chee-Ming

    2017-11-01

    This research proposes an innovative solution for slope stabilization with less environmental footprint: AKARPILES. In Malaysia, landslide has become common civil and environmental problems that cause impacts to the economy, safety and environment. Therefore, effective slope stabilization method helps to improve the safety of public and protect the environment. This study focused on stabilizing surfacial slope failure. The idea of AKARPILES was generated from the tree roots system in slope stabilization. After the piles are installed in the slope and intercepting the slip plane, grout was pumped in and discharged through holes on the piles. The grout then filled the pores in the soil with random flow within the slip zone. SKW mixture was used to simulate the soil slope. There were two designs being proposed in this study and the prototypes were produced by a 3D printer. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. A series of tests were conducted on the single-pile-reinforced slope under vertical slope crest loading condition considering different slope gradients and nail designs. Parameters such as ultimate load, failure time and failure strain were recorded and compared. As comparison with the unreinforced slope, both designs of AKARPILES showed better but different performances in the model tests.

  19. Middle slope contourite deposits and associated sedimentary facies off NE Argentina

    Science.gov (United States)

    Bozzano, Graziella; Violante, Roberto A.; Cerredo, Maria Elena

    2011-12-01

    The Argentine continental margin is characterised by a large contourite depositional system driven by southern-sourced water masses flowing at different water depths. Interest in contourite deposits is increasing in geoscience and related fields, though knowledge of the Argentine contourite system is still limited. In particular, studies based on core data providing detailed descriptions of sedimentary facies are lacking, as are investigations of principal sediment source areas and of key factors controlling sedimentary processes. This study combines visual core description and downcore grain-size analyses as well as petrographic thin-section and magnetic susceptibility analyses of 14 cores from intermediate water depths of 616-1,208 m to characterise contourite deposits on the north-eastern Argentinean slope. Gravel-rich, sandy-silty and muddy contourites as well as hemipelagic facies were identified. The deposition of these contourites was presumably controlled by sea level, the depth range of the Antarctic water mass, climate conditions and windborne terrigenous supply. It is proposed that, during glacial lowstands, muddy contourites were deposited at depths sandy-silty sequences dominated at deeper depths. During the late Pleistocene-Holocene transition, sandy-silty contourites covered the entire middle slope. Hemipelagic facies draped limited sectors of the middle slope when the sea level reached the present-day position and gravel-rich contourites became restricted to contouritic channels and moats. Northern Patagonia and the southern Pampa are the most plausible sources for sediments deposited via along-slope processes, whereas the Tandilia Range is the best candidate for sediments deposited via down-slope processes.

  20. Model tests of geosynthetic reinforced slopes in a geotechnical centrifuge

    International Nuclear Information System (INIS)

    Aklik, P.

    2012-01-01

    Geosynthetic-reinforced slopes and walls became very popular in recent years because of their financial, technical, and ecological advantages. Centrifuge modelling is a powerful tool for physical modelling of reinforced slopes and offers the advantage to observe the failure mechanisms of the slopes. In order to replicate the gravity induced stresses of a prototype structure in a geometrically 1/N reduced model, it is necessary to test the model in a gravitational field N times larger than that of the prototype structure. In this dissertation, geotextile-reinforced slope models were tested in a geotechnical centrifuge to identify the possible failure mechanisms. Slope models were tested by varying slope inclination, tensile strengths of the geotextiles, and overlapping lengths. Photographs of the geotextile reinforced slope models in flight were taken with a digital camera and the soil deformations of geotextile reinforced slopes were evaluated with Particle Image Velocimetry (PIV). The experimental results showed that failure of the centrifuge models initiated at midheight of the slope, and occurred due to geotextile breakage instead of pullout. The location of the shear surface is independent of the tensile strength of the geotextile; it is dependent on the shear strength of the soil. It is logical to see that the required acceleration of the centrifuge at slope failure was decreased with increasing slope inclination. An important contribution to the stability of the slope models was provided by the overlapping of the geotextile layers. It has a secondary reinforcement effect when it was prolonged and passed through the shear surface. Moreover, the location of the shear surface observed with PIV analysis exactly matches the tears of the retrieved geotextiles measured carefully after the centrifuge testing. It is concluded that PIV is an efficient tool to instrument the slope failures in a geotechnical centrifuge.(author) [de

  1. Continuously amplified warming in the Alaskan Arctic: Implications for estimating global warming hiatus

    Science.gov (United States)

    Wang, Kang; Zhang, Tingjun; Zhang, Xiangdong; Clow, Gary D.; Jafarov, Elchin E.; Overeem, Irina; Romanovsky, Vladimir; Peng, Xiaoqing; Cao, Bin

    2017-09-01

    Historically, in situ measurements have been notoriously sparse over the Arctic. As a consequence, the existing gridded data of surface air temperature (SAT) may have large biases in estimating the warming trend in this region. Using data from an expanded monitoring network with 31 stations in the Alaskan Arctic, we demonstrate that the SAT has increased by 2.19°C in this region, or at a rate of 0.23°C/decade during 1921-2015. Meanwhile, we found that the SAT warmed at 0.71°C/decade over 1998-2015, which is 2 to 3 times faster than the rate established from the gridded data sets. Focusing on the "hiatus" period 1998-2012 as identified by the Intergovernmental Panel on Climate Change (IPCC) report, the SAT has increased at 0.45°C/decade, which captures more than 90% of the regional trend for 1951-2012. We suggest that sparse in situ measurements are responsible for underestimation of the SAT change in the gridded data sets. It is likely that enhanced climate warming may also have happened in the other regions of the Arctic since the late 1990s but left undetected because of incomplete observational coverage.

  2. Continuously amplified warming in the Alaskan Arctic: Implications for estimating global warming hiatus

    Science.gov (United States)

    Wang, Kang; Zhang, Tingjun; Zhang, Xiangdong; Clow, Gary D.; Jafarov, Elchin E.; Overeem, Irina; Romanovsky, Vladimir; Peng, Xiaoqing; Cao, Bin

    2017-01-01

    Historically, in situ measurements have been notoriously sparse over the Arctic. As a consequence, the existing gridded data of surface air temperature (SAT) may have large biases in estimating the warming trend in this region. Using data from an expanded monitoring network with 31 stations in the Alaskan Arctic, we demonstrate that the SAT has increased by 2.19°C in this region, or at a rate of 0.23°C/decade during 1921–2015. Meanwhile, we found that the SAT warmed at 0.71°C/decade over 1998–2015, which is 2 to 3 times faster than the rate established from the gridded data sets. Focusing on the “hiatus” period 1998–2012 as identified by the Intergovernmental Panel on Climate Change (IPCC) report, the SAT has increased at 0.45°C/decade, which captures more than 90% of the regional trend for 1951–2012. We suggest that sparse in situ measurements are responsible for underestimation of the SAT change in the gridded data sets. It is likely that enhanced climate warming may also have happened in the other regions of the Arctic since the late 1990s but left undetected because of incomplete observational coverage.

  3. Spatial distribution of mercury in southeastern Alaskan streams influenced by glaciers, wetlands, and salmon

    International Nuclear Information System (INIS)

    Nagorski, Sonia A.; Engstrom, Daniel R.; Hudson, John P.; Krabbenhoft, David P.; Hood, Eran; DeWild, John F.; Aiken, George R.

    2014-01-01

    Southeastern Alaska is a remote coastal-maritime ecosystem that is experiencing increased deposition of mercury (Hg) as well as rapid glacier loss. Here we present the results of the first reported survey of total and methyl Hg (MeHg) concentrations in regional streams and biota. Overall, streams draining large wetland areas had higher Hg concentrations in water, mayflies, and juvenile salmon than those from glacially-influenced or recently deglaciated watersheds. Filtered MeHg was positively correlated with wetland abundance. Aqueous Hg occurred predominantly in the particulate fraction of glacier streams but in the filtered fraction of wetland-rich streams. Colonization by anadromous salmon in both glacier and wetland-rich streams may be contributing additional marine-derived Hg. The spatial distribution of Hg in the range of streams presented here shows that watersheds are variably, yet fairly predictably, sensitive to atmospheric and marine inputs of Hg. -- Highlights: • We sampled 21 streams in southeastern Alaska for water, sediments, and biota. • Aqueous Hg showed significant relationships with wetlands and DOC. • Biota had higher mercury in wetland-rich streams than in glacier-fed streams. • Spawning salmon appear to contribute methylmercury to stream foodwebs. -- This original survey of mercury concentration and form in southeastern Alaskan streamwater and biota shows substantial spatial variation linked to landscape factors and salmon influence

  4. Increases in body weight and nutritional status of transplanted Alaskan caribou

    Directory of Open Access Journals (Sweden)

    Patrick Valkenburg

    2000-04-01

    Full Text Available Body weight and natality rate in ungulates can be useful indices to nutririon, bur they may also be influenced by genetic and climatic factors. Because caribou {Rangifer tarandus granti are distributed as discrete populations of metapopulations (i.e., herds that are usually reproductively isolated from each other for unknown periods, it is difficult to separate the influence of genetics and nutrition on body weight, especially where historical data are lacking. To help elucidate the influence of nutrition on potential variation in body weight and natality of caribou in Alaska, we reviewed data for body weight and natality in 5 populations which resulted from Transplants to previously ungrazed ranges, or to areas where reindeer and caribou had been absent for many decades. In 2 of 5 populations body weight increased significantly, and likely increased in the other 3 populations, but data were insufficient. Natality rate increased in all 5 populations, proportion of fecund yearlings was high and 3 of the 5 newly established herds increased at about the maximum biological potential for the species (lambda=1.35. In the Adak transplant, a lactating yearling was documented. These 5 transplanted populations provide additional evidence that body weight and natality rate in Alaskan caribou are sensitive to changes in population density and relatively short-term (i.e., 10 years increases in grazing pressure independenr of climate and genetics.

  5. Cost-Optimal Pathways to 75% Fuel Reduction in Remote Alaskan Villages: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Simpkins, Travis; Cutler, Dylan; Hirsch, Brian; Olis, Dan; Anderson, Kate

    2015-10-28

    There are thousands of isolated, diesel-powered microgrids that deliver energy to remote communities around the world at very high energy costs. The Remote Communities Renewable Energy program aims to help these communities reduce their fuel consumption and lower their energy costs through the use of high penetration renewable energy. As part of this program, the REopt modeling platform for energy system integration and optimization was used to analyze cost-optimal pathways toward achieving a combined 75% reduction in diesel fuel and fuel oil consumption in a select Alaskan village. In addition to the existing diesel generator and fuel oil heating technologies, the model was able to select from among wind, battery storage, and dispatchable electric heaters to meet the electrical and thermal loads. The model results indicate that while 75% fuel reduction appears to be technically feasible it may not be economically viable at this time. When the fuel reduction target was relaxed, the results indicate that by installing high-penetration renewable energy, the community could lower their energy costs by 21% while still reducing their fuel consumption by 54%.

  6. Alaskan wild berry resources and human health under the cloud of climate change.

    Science.gov (United States)

    Kellogg, Joshua; Wang, Jinzhi; Flint, Courtney; Ribnicky, David; Kuhn, Peter; De Mejia, Elvira González; Raskin, Ilya; Lila, Mary Ann

    2010-04-14

    Wild berries are integral dietary components for Alaska Native people and a rich source of polyphenolic metabolites that can ameliorate metabolic disorders such as obesity and diabetes. In this study, five species of wild Alaskan berries (Vaccinium ovalifolium , Vaccinium uliginosum , Rubus chamaemorus , Rubus spectabilis , and Empetrum nigrum) were screened for bioactivity through a community-participatory research method involving three geographically distinct tribal communities. Compositional analysis by HPLC and LC-MS(2) revealed substantial site-specific variation in anthocyanins (0.01-4.39 mg/g of FW) and proanthocyanidins (0.74-6.25 mg/g of FW) and identified A-type proanthocyanidin polymers. R. spectabilis increased expression levels of preadipocyte factor 1 (182%), and proanthocyanidin-enriched fractions from other species reduced lipid accumulation in 3T3-L1 adipocytes. Selected extracts reduced serum glucose levels in C57BL/6J mice by up to 45%. Local observations provided robust insights into effects of climatic fluctuations on berry abundance and quality, and preliminary site-specific compositional and bioactivity differences were noted, suggesting the need to monitor this Alaska Native resource as climate shifts affect the region.

  7. Alaskan Permafrost Groundwater Storage Changes Derived from GRACE and Ground Measurements

    Directory of Open Access Journals (Sweden)

    Vladimir E. Romanovsky

    2011-02-01

    Full Text Available The Arctic is in transition from climate-driven thawing of permafrost. We investigate satellite-derived water equivalent mass changes, snow water equivalent with in situ measurements of runoff and ground-survey derived geoid models from 1999 through 2009. The Alaskan Arctic coastal plain groundwater storage (including wetland bog, thaw pond and lake is increasing by 1.15 ± 0.65 km3/a (area-average 1.10 ± 0.62 cm/a, and Yukon River watershed groundwater storage is decreasing by 7.44 ± 3.76 km3/a (area‑average 0.79 ± 0.40 cm/a. Geoid changes show increases within the Arctic coastal region and decreases within the Yukon River watershed. We hypothesize these changes are linked to the development of new predominately closed- and possibly open-talik in the continuous permafrost zone under large thaw lakes with increases of lakes and new predominately open-talik and reduction of permafrost extent in the discontinuous and sporadic zones with decreases of thaw lakes.

  8. Extent of endocrine disruption in fish of western and Alaskan National Parks

    Science.gov (United States)

    Schreck, Carl B.; Kent, Michael

    2013-01-01

    In 2008 2009, 998 fish were collected from 43 water bodies across 11 western Alaskan national parks and analyzed for reproductive abnormalities. Exposure to estrogenic substances such as pesticides can induce abnormalities like intersex. Results suggest there is a greater propensity for male intersex fish collected from parks located in the Rocky Mountains, and specifically in Rocky Mountain NP. Individual male intersex fish were also identified at Lassen Volcanic, Yosemite, and WrangellSt. Elias NPs. The preliminary finding of female intersex was determined to be a false positive. The overall goal of this project was to assess the general health of fish from eleven western national parks to infer whether health impacts may be linked to contaminant health thresholds for animal andor human health. This was accomplished by evaluating the presence of intersex fish with eggs developing in male gonads or sperm developing in female gonads using histology. In addition, endocrine disrupting compounds and other contaminants were quantified in select specimens. General histologic appearance of the gonadal tissue and spleen were observed to assess health.

  9. Microbial activity in Alaskan taiga soils contaminated by crude oil in 1976

    International Nuclear Information System (INIS)

    Monroe, E.M.; Lindstrom, J.E.; Brown, E.J.; Raddock, J.F.

    1995-01-01

    Biodegradation, often measured via microbial activity, includes destruction of environmental pollutants by living microorganisms and is dependent upon many physical and chemical factors. Effects of mineral nutrients and organic matter on biodegradation of Prudhoe Bay crude oil were investigated at a nineteen-year-old oil spill site in Alaskan taiga. Microcosms of two different soil types from the spill site; one undeveloped soil with forest litter and detritus (O horizon) and one more developed with lower organic content (A horizon), were treated with various nitrogen and phosphorus amendments, and incubated for up to six weeks. Each microcosm was sampled periodically and assayed for hydrocarbon mineralization potential using radiorespirometry, for total carbon dioxide respired using gas chromatography, and for numbers of hydrocarbon-degrading bacteria and heterotrophic bacteria using most probable number counting techniques. Organic matter in the O horizon soil along with combinations of mineral nutrients were found to stimulate microbial activity. No combination of mineral nutrient additions to the A horizon soil stimulated any of the parameters above those measured in control microcosms. The results of this study indicate that adding mineral nutrients and tilling the O horizon into the A horizon of subarctic soils contaminated with crude oil, would stimulate microbial activity, and therefore the biodegradation potential, ultimately increasing the rate of destruction of crude oil in these soils

  10. Seabirds as a subsistence and cultural resource in two remote Alaskan communities

    Directory of Open Access Journals (Sweden)

    Rebecca C. Young

    2014-12-01

    Full Text Available Small rural Alaskan communities face many challenges surrounding rapid social and ecological change. The role of local subsistence resources may change over time because of changes in social perception, economic need, and cultural patterns of use. We look at the Bering Sea's Pribilof Islands, comprising two very small communities, and investigate the relationship between the local residents and seabirds as a natural resource. Seabirds may strengthen ties to older ways of life and have potential for future economic opportunities, or modernization may direct interest away from seabirds as a cultural and economic resource. We conducted a survey and interviews of residents of the two Pribilof Island communities, St. Paul and St. George, to assess opinions toward seabirds and harvest levels. Seabirds were generally regarded as important both to individuals and the wider community. However, current levels of subsistence harvest are low, and few people continue to actively harvest or visit seabird colonies. Respondents expressed desire for greater knowledge about seabirds and also concerns about the current economy of the islands and a lack of future development prospects. Despite the challenging economic conditions, the villages retain a strong sense of community and place value on their environment and on seabirds. Surveys indicated an interest in developing eco-tourism based around local resources, including seabirds, as a way to improve the economy.

  11. [North] Korea.

    Science.gov (United States)

    1986-05-01

    In 1985, the population of the Democratic People's Republic of Korea (North Korea) stood at 20 million, with an annual growth rate of 2.3%. The infant mortality rate was 30/1000 live births and life expectancy was 66 years. The gross national product (GNP) was US$23 billion in 1984, with a per capita GNP of $1175. Both North Korea's labor force and natural resources have been concentrated in recent years on an effort to achieve rapid economic development. During the early 1970s, a large-scale modernization program involving the importation of Western technology, primarily in the heavy industiral sectors of the economy, was attempted and resulted in a massive foreign debt. North Korea has a strongly centralized government under the control of the communist Korean Workers' Party. Literacy in the country is at the 99% level. Medical treatment is free. There is 1 physician/600 population and 1 hospital bed/350 inhabitants.

  12. From incipient slope instability through slope deformation to catastrophic failure - Different stages of failure development on the Ivasnasen and Vollan rock slopes (western Norway)

    Science.gov (United States)

    Oppikofer, T.; Saintot, A.; Hermanns, R. L.; Böhme, M.; Scheiber, T.; Gosse, J.; Dreiås, G. M.

    2017-07-01

    The long-term evolution of rock slope failures involves different stages, from incipience of slope instability to catastrophic failure, through a more or less long-lasting slope deformation phase that also involves creeping or sliding. Topography, lithology, and structural inheritance are the main intrinsic factors that influence this evolution. Here, we investigate the role of these intrinsic factors on the rock slope failure development of the Ivasnasen and Vollan rock slopes (Sunndal Valley, western Norway) using a multitechnique approach that includes geomorphologic and structural field mapping, kinematic analysis, terrestrial cosmogenic nuclide exposure dating, topographic reconstruction, and deformation quantification. Ivasnasen is a rock slope failure complex with several past rock slope failures and a present unstable rock slope, located on a cataclinal NW-facing slope and developed in augen gneiss. Vollan on the opposite valley side is a deep-seated gravitational slope deformation (DSGSD) affecting the whole mountainside, developed in quartzite in the upper part and micaschist in the lower part. These different lithologies belong to different nappe complexes that were emplaced and folded into a series of syn- and anticlines during the Caledonian orogeny. These folds lead to different lithologies being exposed in different structural orientations on the opposite valley flanks, which in turn leads to different types and evolution of rock slope failures. At Ivasnasen the 45°-55° NW-dipping ductile foliation allowed for a fairly simple planar sliding mechanism for the 1.2 million m3 post-glacial rock slope failure. Failure occurred ca. 3.3 ka ago after a short period of prefailure deformation. For the present 2.2 million m3 unstable rock slope at Ivasnasen, a steepening of the foliation at the toe impedes such a mechanism and up to 10 m of displacement has not lead to a catastrophic failure yet. The Vollan DSGSD is characterized by a steep major back scarp

  13. Simulating the seismic behaviour of soil slopes and embankments

    DEFF Research Database (Denmark)

    Zania, Varvara; Tsompanakis, Yiannis; Psarropoulos, Prodromos

    2010-01-01

    In the current study the clarification of the main assumptions, related to the two most commonly used methods of seismic slope stability analysis (pseudostatic and permanent deformation) is attempted. The seismic permanent displacements and the corresponding seismic coefficients were determined via...... parametric dynamic numerical analyses taking into account not only the main parameters dominating the seismic slope stability, but also the inherent assumptions of the applied approaches that affect the obtained results. The investigation conclude to a realistic procedure for seismic slope stability...

  14. Overpressure, Flow Focusing, Compaction and Slope Stability on the continental slope: Insights from IODP Expedition 308

    Science.gov (United States)

    Flemings, P. B.

    2010-12-01

    Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have pre-conditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the large-scale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

  15. A Hybrid FEM-ANN Approach for Slope Instability Prediction

    Science.gov (United States)

    Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.

    2016-09-01

    Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.

  16. Analysis of Rainfall Infiltration Law in Unsaturated Soil Slope

    Science.gov (United States)

    Zhang, Gui-rong; Qian, Ya-jun; Wang, Zhang-chun; Zhao, Bo

    2014-01-01

    In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering the characteristics of slope and rainfall, the key factors affecting rainfall infiltration of slope, including hydraulic properties, water storage capacity (θ s - θ r), soil types, rainfall intensities, and antecedent and subsequent infiltration rates on unsaturated soil slope, are discussed by using theory analysis and numerical simulation technology. Based on critical factors changing, this paper presents three calculation models of rainfall infiltrability for unsaturated slope, including (1) infiltration model considering rainfall intensity; (2) effective rainfall model considering antecedent rainfall; (3) infiltration model considering comprehensive factors. Based on the technology of system response, the relationship of rainfall and infiltration is described, and the prototype of regression model of rainfall infiltration is given, in order to determine the amount of rain penetration during a rain process. PMID:24672332

  17. [Analysis of related factors of slope plant hyperspectral remote sensing].

    Science.gov (United States)

    Sun, Wei-Qi; Zhao, Yun-Sheng; Tu, Lin-Ling

    2014-09-01

    In the present paper, the slope gradient, aspect, detection zenith angle and plant types were analyzed. In order to strengthen the theoretical discussion, the research was under laboratory condition, and modeled uniform slope for slope plant. Through experiments we found that these factors indeed have influence on plant hyperspectral remote sensing. When choosing slope gradient as the variate, the blade reflection first increases and then decreases as the slope gradient changes from 0° to 36°; When keeping other factors constant, and only detection zenith angle increasing from 0° to 60°, the spectral characteristic of slope plants do not change significantly in visible light band, but decreases gradually in near infrared band; With only slope aspect changing, when the dome meets the light direction, the blade reflectance gets maximum, and when the dome meets the backlit direction, the blade reflectance gets minimum, furthermore, setting the line of vertical intersection of incidence plane and the dome as an axis, the reflectance on the axis's both sides shows symmetric distribution; In addition, spectral curves of different plant types have a lot differences between each other, which means that the plant types also affect hyperspectral remote sensing results of slope plants. This research breaks through the limitations of the traditional vertical remote sensing data collection and uses the multi-angle and hyperspectral information to analyze spectral characteristics of slope plants. So this research has theoretical significance to the development of quantitative remote sensing, and has application value to the plant remote sensing monitoring.

  18. Risk assessment of debris flow hazards in natural slope

    Science.gov (United States)

    Choi, Junghae; Chae, Byung-gon; Liu, Kofei; Wu, Yinghsin

    2016-04-01

    The study area is located at north-east part of South Korea. Referring to the map of landslide sus-ceptibility (KIGAM, 2009) from Korea Institute of Geoscience and Mineral Resources (KIGAM for short), there are large areas of potential landslide in high probability on slope land of mountain near the study area. Besides, recently some severe landslide-induced debris flow hazards occurred in this area. So this site is convinced to be prone to debris flow haz-ards. In order to mitigate the influence of hazards, the assessment of potential debris flow hazards is very important and essential. In this assessment, we use Debris-2D, debris flow numerical program, to assess the potential debris flow hazards. The worst scenario is considered for simulation. The input mass sources are determined using landslide susceptibility map. The water input is referred to the daily accumulative rainfall in the past debris flow event in study area. The only one input material property, i.e. yield stress, is obtained using calibration test. The simulation results show that the study area has po-tential to be impacted by debris flow. Therefore, based on simulation results, to mitigate debris flow hazards, we can propose countermeasures, including building check dams, constructing a protection wall in study area, and installing instruments for active monitoring of debris flow hazards. Acknowledgements:This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2012M3A2A1050983)

  19. Repeat Photography of Alaskan Glaciers and Landscapes as Both Art and as a Means of Communicating Climat Change

    Science.gov (United States)

    Molnia, B. F.

    2013-12-01

    For nearly 15 years, I have used repeat photography of Alaskan glaciers and landscapes to communicate to fellow scientists, policymakers, the media, and society that Alaskan glaciers and landscapes have been experiencing significant change in response to post-Little Ice Age climate change. I began this pursuit after being contacted by a U.S. Department of the Interior senior official who requested unequivocal and unambiguous documentation that climate change was real and underway. After considering several options as to how best respond to this challenge, I decided that if a picture is worth a thousand words, then a pair of photographs, both with the same field of view, spanning a century or more, and showing dramatic differences, would speak volumes to documenting that dynamic climate change is occurring over a very broad region of Alaska. To me, understating the obvious with photographic pairs was the best mechanism to present irrefutable, unambiguous, nonjudgmental, as well as unequivocal visual documentation that climate change was both underway and real. To date, more than 150 pairs that meet these criteria have been produced. What has surprised me most is that the many of the photographs contained in the pairs present beautiful images of stark, remote landscapes that convey the majestic nature of this dynamic region with its unique topography and landscapes. Typically, over periods of just several decades, the photographed landscapes change from black and white to blue and green. White ice becomes blue water and dark rock becomes lush vegetation. Repeat photography is a technique in which a historical photograph and a modern photograph, both having the same field of view, are compared and contrasted to quantitatively and qualitatively determine their similarities and differences. I have used this technique from both ground-based photo stations and airborne platforms at Alaskan locations in Kenai Fjords National Park, Glacier Bay National Park and Preserve

  20. Edible North

    DEFF Research Database (Denmark)

    Munk, Anders Kristian

    2012-01-01

    -constitutive role in the formation of publics (Marres 2007) and the ways in which they are themselves reconfigured as ‘matters of concern’ (Latour 2003) in this process. I draw on digital cartographies and fieldwork carried out under the Carlsberg funded project Edible North: Mapping the ’New Nordic Food...

  1. An experimental test of well-described vegetation patterns across slope aspects using woodland herb transplants and manipulated abiotic drivers.

    Science.gov (United States)

    Warren, Robert J

    2010-03-01

    *The ubiquitous transition of plant communities across slope aspects is a well-described, but rarely tested, ecological dynamic. Aspect position is often used as a proxy for microclimate changes in moisture, light and temperature, but these abiotic drivers are seldom decoupled and very rarely manipulated across slope aspects. *To investigate the mechanisms and demographic stages driving the observed distribution patterns of two woodland herbs in the southeastern USA, seeds and adults were transplanted across north- and south-facing slopes, and moisture and light were experimentally manipulated. *Stage- and species-specific abiotic responses resulted in similar landscape-level patterning for Hexastylis arifolia and Hepatica nobilis, but the underlying abiotic drivers were unique. Adult rather than seed survival best explained the natural distributions across slope aspects, and Hexastylis arifolia was limited by higher temperature, whereas Hepatica nobilis was limited by lower soil moisture. *The stage- and species-specific responses indicated that the use of slope aspect to explain plant distributions not only obfuscates explanatory mechanisms, but probably undermines the portability of results. As abiotic drivers, not topographical proxies, are projected to shift with global climate change, distribution research requires direct abiotic data in association with key demographic stages rather than topographical proxies.

  2. Hydrologic behavior of model slopes with synthetic water repellent soils

    Science.gov (United States)

    Zheng, Shuang; Lourenço, Sérgio D. N.; Cleall, Peter J.; Chui, Ting Fong May; Ng, Angel K. Y.; Millis, Stuart W.

    2017-11-01

    In the natural environment, soil water repellency decreases infiltration, increases runoff, and increases erosion in slopes. In the built environment, soil water repellency offers the opportunity to develop granular materials with controllable wettability for slope stabilization. In this paper, the influence of soil water repellency on the hydrological response of slopes is investigated. Twenty-four flume tests were carried out in model slopes under artificial rainfall; soils with various wettability levels were tested, including wettable (Contact Angle, CA 90°). Various rainfall intensities (30 mm/h and 70 mm/h), slope angles (20° and 40°) and relative compactions (70% and 90%) were applied to model the response of natural and man-made slopes to rainfall. To quantitatively assess the hydrological response, a number of measurements were made: runoff rate, effective rainfall rate, time to ponding, time to steady state, runoff acceleration, total water storage and wetting front rate. Overall, an increase in soil water repellency reduces infiltration and shortens the time for runoff generation, with the effects amplified for high rainfall intensity. Comparatively, the slope angle and relative compaction had only a minor contribution to the slope hydrology. The subcritical water repellent soils sustained infiltration for longer than both the wettable and water repellent soils, which presents an added advantage if they are to be used in the built environment as barriers. This study revealed substantial impacts of man-made or synthetically induced soil water repellency on the hydrological behavior of model slopes in controlled conditions. The results shed light on our understanding of hydrological processes in environments where the occurrence of natural soil water repellency is likely, such as slopes subjected to wildfires and in agricultural and forested slopes.

  3. IMPROVED LARGE-SCALE SLOPE ANALYSIS ON MARS BASED ON CORRELATION OF SLOPES DERIVED WITH DIFFERENT BASELINES

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2017-07-01

    Full Text Available The surface slopes of planetary bodies are important factors for exploration missions, such as landing site selection and rover manoeuvre. Generally, high-resolution digital elevation models (DEMs such as those generated from the HiRISE images on Mars are preferred to generate detailed slopes with a better fidelity of terrain features. Unfortunately, high-resolution datasets normally only cover small area and are not always available. While lower resolution datasets, such as MOLA, provide global coverage of the Martian surface. Slopes generated from the low-resolution DEM will be based on a large baseline and be smoothed from the real situation. In order to carry out slope analysis at large scale on Martian surface based low-resolution data such as MOLA data, while alleviating the smoothness problem of slopes due to its low resolution, this paper presents an amplifying function of slopes derived from low-resolution DEMs based on the relationships between DEM resolutions and slopes. First, slope maps are derived from the HiRISE DEM (meter-level resolution DEM generated from HiRISE images and a series of down-sampled HiRISE DEMs. The latter are used to simulate low-resolution DEMs. Then the high-resolution slope map is down- sampled to the same resolution with the slope map from the lower-resolution DEMs. Thus, a comparison can be conducted pixel-wise. For each pixel on the slope map derived from the lower-resolution DEM, it can reach the same value with the down-sampled HiRISE slope by multiplying an amplifying factor. Seven sets of HiRISE images with representative terrain types are used for correlation analysis. It shows that the relationship between the amplifying factors and the original MOLA slopes can be described by the exponential function. Verifications using other datasets show that after applying the proposed amplifying function, the updated slope maps give better representations of slopes on Martian surface compared with the original

  4. USLE, RUSLE and WEPP models used in mining restored hill slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Ubierna, S.; Casermeiro Martinez, M. A.; Nicolay Ibarra, J. M.

    2009-07-01

    One of the main problems affecting mining restoration is erosion, which limits the development of functional soils and plant communities. The eroded sediment pollutes and degrades the natural river systems. the objective of this work is to test some of the most used models: USLE (Wischmeier and Smith, 1965, 1978) and RUSLE 1.06 (Toy and Foster, 1998) and WEPP (Nearing et al., 1989), for the case of slopes derived from mining reclamation. The study area is a dump in El Moral coal mine (Utrillas), 60 km. north of Teruel city. We selected three artificial slopes, one with a topsoil substrate and two overburden covered in order to measure the sediment production during a year. After the comparison between estimated and measured erosion rates two conclusions can be stated: a) RUSLE 1.06 gives the best estimations in most of the cases. However WEPP in its annual option and for the top soiled slope, works better than RUSLE 1.06. (Author) 16 refs.

  5. Degradation of terraced slopes in Mediterranean conditions

    Science.gov (United States)

    Tsermegas, I.; DłuŻewski, M.; Biejat, K.; Szynkiewicz, A.

    2012-04-01

    Agricultural terraces with dry-stone walls take the largest area of all man-made landforms in Mediterranean mountain regions. Despite on that their contemporary morphodynamics have not been the subject of many studies. It is a significant problem both from a scientific and a practical point of view. The aim of the study was to estimate the influence of relief, lithology, climatic conditions, methods of wall construction and actual agricultural practice on the degradation of agricultural terraces. A field study was conducted in Greece on 7 plots with the overall area of over 42 000 m2 - on the east Crete and on two Aegean islands - Ikaria and Thera. The analysis was conducted on terraced slopes with gradient of 8-23o, built of granitoids, gneisses, crystalline schists, limestones, crystalline dolomites and volcanic tuffs. There was identified the types of terrace walls. Metrical features of terrace systems were ascertained on the basis of GPS RTK measurement. Terrace material petrography and grain size distribution was identified for regolith an soil samples taken from the selected outcrops which were recognized as being representative for 239 georadar profiles of the joint length of over 2500 m. On that basis the volume of each terrace material was defined. The rills cutting the fields and the walls were measured. The infiltration rate was also taken in 130 points. Reasearch showed that regardless of metrical features of terraces, soil grain size distribution and thickness of the terrace material, the most important reason for the destruction of terrace walls is the abandonment of cultivated areas. Changes in cultivation methods and the introduction of pasturage visibly accelerate the degradation processes. On areas unused for 30 years terrace walls are destroyed on over 25% of their length. It concerns both the areas on which filtration coefficient (k) reaches about 10-5m•s-1 as well as the ones where it is a 100 times lower. The least varied values (10-6-10-5m

  6. Rock-slope failure activity and geological crises in western Norway

    Science.gov (United States)

    Hilger, Paula; Hermanns, Reginald L.; Myhra, Kristin S.; Gosse, John C.; Ivy-Ochs, Susan; Etzelmüller, Bernd

    2017-04-01

    In Norway a compilation of terrestrial cosmogenic nuclide (TCN) ages of rock-avalanche deposits suggests a close link of rock-slope failures related to deglaciation. Although ages spread over several thousand years at the end of the Late Pleistocene, 50% of all documented events occurred within 1000 years after deglaciation. It is therefore likely that debuttressing triggered most of the events. The same data set suggests that 25% of the events occurred during a period stretching until the Holocene thermal maximum (HTM). These events might be interpreted as possible reactions to additional factors such as the thawing of high-altitude permafrost. An example of a geological crisis following deglaciation and before the HTM are seven lobate rock-avalanche deposits mapped under the slope of the Vora mountain (1450 m asl.) in the Nordfjord area of western Norway. Three events of this rock-slope failure cluster date within a short time period of 2000 years, where modelling studies indicate that high-altitude permafrost was present. After the HTM rock-slope failures are distributed temporally and spatially rather evenly throughout the Holocene and western Norway. But there are two independent local clusters with frequent rock slides during a short time span. (1) At the active Mannen rock-slope instability several rock-avalanche and rockslide deposits were mapped on the valley bottom. Stratigraphic relations combined with TCN dating suggest that at least one event occurred when the valley bottom was below the marine limit. TCN ages of further four lobes cluster around 5.2 ka BP, which does not coincide with any other rock-avalanche occurrence in the region. The top of the north facing 1295 m high unstable slope concurs with the currently estimated permafrost boundary. Preliminary TCN ages of the sliding surface indicate that larger parts of the mountain did not become active until the climate maximum. It is likely that due to structural complexity not allowing for any easy

  7. Linkages Among Climate, Fire, and Thermoerosion in Alaskan Tundra Over the Past Three Millennia

    Science.gov (United States)

    Chipman, M. L.; Hu, F. S.

    2017-12-01

    Amplified Arctic warming may facilitate novel tundra disturbance regimes, as suggested by recent increases in the rate and extent of thermoerosion and fires in some tundra areas. Thermoerosion and wildfire can exacerbate warming by releasing large permafrost carbon stocks, and interactions between disturbance regimes can lead to complex ecosystem feedbacks. We conducted geochemical and charcoal analyses of lake sediments from an Alaskan lake to identify thermoerosion and fire events over the past 3,000 years. Thermoerosion was inferred from lake sediments in the context of modern soil data from retrogressive thaw slumps (RTS). Magnetic susceptibility (MS), Ca:K, and Ca:Sr increased with depth in modern RTS soils and were higher on recently exposed than older slump surfaces. Peaks in bulk density, % CaCO3, Ca:K, Ca:Sr, and MS values in the sediments suggest at least 18 thermoerosion events in the Loon Lake watershed over the past 3,000 years. Charcoal analysis identifies 22 fires over the same period at this site. Temporal variability in these records suggests climate-driven responses of both thermoerosion and fire disturbance regimes, with fewer RTS episodes and fire events during the Little Ice Age than the Medieval Climate Anomaly. Moreover, RTS activity lagged behind catchment fires by 20-30 years (>90% confidence interval), implying that fires facilitated thermoerosion on decadal time scales, possibly because of prolonged active-layer deepening following fire and postfire proliferation of insulative shrub cover. These results highlight the potential for complex interactions between climate, vegetation, and tundra disturbance in response to ongoing warming.

  8. Connecting Alaskan Youth, Elders, and Scientists in Climate Change Research and Community Resilience

    Science.gov (United States)

    Spellman, K.; Sparrow, E.

    2017-12-01

    Integrated science, technology, engineering and math (STEM) solutions and effective, relevant learning processes are required to address the challenges that a changing climate presents to many Arctic communities. Learning that can both enhance a community's understanding and generate new knowledge about climate change impacts at both local and continental scales are needed to efficiently build the capacity to navigate these changes. The Arctic and Earth STEM Integrating GLOBE and NASA (SIGNs) program is developing a learning model to engage Alaskan rural and indigenous communities in climate change learning, research and action. Youth, elders, educators, community leaders and scientists collaborate to address a pressing local climate change concern. The program trains teams of educators and long-time community members on climate change concepts and environmental observing protocols in face-to-face or online workshops together with Arctic and NASA subject matter experts. Community teams return to their community to identify local data or information needs that align with their student's interests and the observations of local elders. They deepen their understanding of the subject through culturally responsive curriculum materials, and collaborate with a scientist to develop an investigation with their students to address the identified need. Youth make observations using GLOBE (Global Learning and Observations to Benefit the Environment) protocols that best fit the issue, analyze the data they have collected, and utilize indigenous or knowledge, and NASA data to address the issue. The use of GLOBE protocols allow for communities to engage in climate change research at both local and global scales, as over 110 nations worldwide are using these standardized protocols. Teams work to communicate their investigation results back to their community and other scientists, and apply their results to local stewardship action or climate adaptation projects. In this

  9. Greater shrub dominance alters breeding habitat and food resources for migratory songbirds in Alaskan arctic tundra.

    Science.gov (United States)

    Boelman, Natalie T; Gough, Laura; Wingfield, John; Goetz, Scott; Asmus, Ashley; Chmura, Helen E; Krause, Jesse S; Perez, Jonathan H; Sweet, Shannan K; Guay, Kevin C

    2015-04-01

    Climate warming is affecting the Arctic in multiple ways, including via increased dominance of deciduous shrubs. Although many studies have focused on how this vegetation shift is altering nutrient cycling and energy balance, few have explicitly considered effects on tundra fauna, such as the millions of migratory songbirds that breed in northern regions every year. To understand how increasing deciduous shrub dominance may alter breeding songbird habitat, we quantified vegetation and arthropod community characteristics in both graminoid and shrub dominated tundra. We combined measurements of preferred nest site characteristics for Lapland longspurs (Calcarius lapponicus) and Gambel's White-crowned sparrows (Zonotrichia leucophrys gambelii) with modeled predictions for the distribution of plant community types in the Alaskan arctic foothills region for the year 2050. Lapland longspur nests were found in sedge-dominated tussock tundra where shrub height does not exceed 20 cm, whereas White-crowned sparrows nested only under shrubs between 20 cm and 1 m in height, with no preference for shrub species. Shrub canopies had higher canopy-dwelling arthropod availability (i.e. small flies and spiders) but lower ground-dwelling arthropod availability (i.e. large spiders and beetles). Since flies are the birds' preferred prey, increasing shrubs may result in a net enhancement in preferred prey availability. Acknowledging the coarse resolution of existing tundra vegetation models, we predict that by 2050 there will be a northward shift in current White-crowned sparrow habitat range and a 20-60% increase in their preferred habitat extent, while Lapland longspur habitat extent will be equivalently reduced. Our findings can be used to make first approximations of future habitat change for species with similar nesting requirements. However, we contend that as exemplified by this study's findings, existing tundra modeling tools cannot yet simulate the fine-scale habitat

  10. "A Comparison of Several Methods in a Rock Slope Stability ...

    African Journals Online (AJOL)

    This researchuses the mentioned methods and principles in the stability analysis of some rock slopes in an open pit mine in Syria, that is Khneifees phosphate mine. The importance of this researchis that it shows the role of kinematical analysis in minimizing efforts when verifying the safety of rock slopes in site, and when ...

  11. After the Slippery Slope: Dutch Experiences on Regulating Active Euthanasia

    NARCIS (Netherlands)

    Boer, Th.A.

    2003-01-01

    “When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward.” If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery-slope argument, however, is by

  12. assessment of slope stability around gilgel gibe-ii hydroelectric

    African Journals Online (AJOL)

    preferred customer

    ... are steep and valleys are deep with low vegetation cover. Along the road from Fofa town to powerhouse II, the slope cuts are steep, which overhang at places. Thus, an attempt has been made to analyze the stability condition of potential unstable slopes along the road between Fofa town and Gilgel-Gibe Hydro- power II.

  13. Preliminary Analysis of Slope Stability in Kuok and Surrounding Areas

    Directory of Open Access Journals (Sweden)

    Dewandra Bagus Eka Putra

    2016-12-01

    Full Text Available The level of slope influenced by the condition of the rocks beneath the surface. On high level of slopes, amount of surface runoff and water transport energy is also enlarged. This caused by greater gravity, in line with the surface tilt from the horizontal plane. In other words, topsoil eroded more and more. When the slope becomes twice as steep, then the amount of erosion per unit area be 2.0 - 2.5 times more. Kuok and surrounding area is the road access between the West Sumatra and Riau which plays an important role economies of both provinces. The purpose of this study is to map the locations that have fairly steep slopes and potential mode of landslides. Based on SRTM data obtained,  the roads in Kuok area has a minimum elevation of + 33 m and a maximum  + 217.329 m. Rugged road conditions with slope ranging from 24.08 ° to 44.68 ° causing this area having frequent landslides. The result of slope stability analysis in a slope near the Water Power Plant Koto Panjang, indicated that mode of active failure is toppling failure or rock fall and the potential zone of failure is in the center part of the slope.

  14. RMS slope of exponentially correlated surface roughness for radar applications

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    2000-01-01

    In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum...

  15. Slope Monitoring using Total Station: What are the Challenges and ...

    African Journals Online (AJOL)

    ... survey perspective on the typical problems that can be expected during slope monitoring using total station (also known as prism monitoring) and second, to suggest ways of mitigating such problems. The aim is to create awareness of the implications of incorrect use or negligence during slope monitoring surveys utilising ...

  16. Effects of slope position and fertilization on the performance of ...

    African Journals Online (AJOL)

    FARO 45 (ITA 257) early maturing upland variety of rice was used as the test crop at each slope level. The experiment was a 3 x 2 factorial combination of three slopes (upper, middle and hydromorphic fringe) and two fertilizations (without fertilizer and with fertilizer) in a Randomized Complete Block Design (RCBD), ...

  17. Assessment of slope stability and remedial measures around Gilgel ...

    African Journals Online (AJOL)

    (1995) technique, whereas the slope having wedge mode of failure was analyzed by 'SASW' computer program. The stability analysis was carried out for the existing and anticipated worst conditions. The results indicate that all critical slopes in the study area are stable for the existing conditions, represented by dry static ...

  18. Assessment of rock mass decay in artificial slopes

    NARCIS (Netherlands)

    Huisman, M.

    2006-01-01

    This research investigates the decay of rock masses underlying slopes, and seeks to quantify the relations of such decay with time and geotechnical parameters of the slope and rock mass. Decay can greatly affect the geotechnical properties of rocks within engineering timescales, and may induce a

  19. Analysis of Covariance and Randomized Block Design with Heterogeneous Slopes.

    Science.gov (United States)

    Klockars, Alan J.; Beretvas, S. Natasha

    2001-01-01

    Compared the Type I error rate and the power to detect differences in slopes and additive treatment effects of analysis of covariance (ANCOVA) and randomized block designs through a Monte Carlo simulation. Results show that the more powerful option in almost all simulations for tests of both slope and means was ANCOVA. (SLD)

  20. Slope Monitoring using Total Station: What are the Challenges and ...

    African Journals Online (AJOL)

    Afeni

    implications of incorrect use or negligence during slope monitoring surveys utilising a total station. 1. Introduction ... monitoring frequency depends on the nature of the rock type, operations around the slope and the objectives of ... to do with correct design, legal compliance, monitoring requirements and systems design that.

  1. Circum-North Pacific tectonostratigraphic terrane map

    Science.gov (United States)

    Nokleberg, Warren J.; Parfenov, Leonid M.; Monger, James W.H.; Baranov, Boris B.; Byalobzhesky, Stanislav G.; Bundtzen, Thomas K.; Feeney, Tracey D.; Fujita, Kazuya; Gordey, Steven P.; Grantz, Arthur; Khanchuk, Alexander I.; Natal'in, Boris A.; Natapov, Lev M.; Norton, Ian O.; Patton, William W.; Plafker, George; Scholl, David W.; Sokolov, Sergei D.; Sosunov, Gleb M.; Stone, David B.; Tabor, Rowland W.; Tsukanov, Nickolai V.; Vallier, Tracy L.; Wakita, Koji

    1994-01-01

    The companion tectonostratigraphic terrane and overlap assemblage of map the Circum-North Pacific presents a modern description of the major geologic and tectonic units of the region. The map illustrates both the onshore terranes and overlap volcanic assemblages of the region, and the major offshore geologic features. The map is the first collaborative compilation of the geology of the region at a scale of 1:5,000,000 by geologists of the Russian Far East, Japanese, Alaskan, Canadian, and U.S.A. Pacific Northwest. The map is designed to be a source of geologic information for all scientists interested in the region, and is designed to be used for several purposes, including regional tectonic analyses, mineral resource and metallogenic analyses (Nokleberg and others, 1993, 1994a), petroleum analyses, neotectonic analyses, and analyses of seismic hazards and volcanic hazards. This text contains an introduction, tectonic definitions, acknowledgments, descriptions of postaccretion stratified rock units, descriptions and stratigraphic columns for tectonostratigraphic terranes in onshore areas, and references for the companion map (Sheets 1 to 5). This map is the result of extensive geologic mapping and associated tectonic studies in the Russian Far East, Hokkaido Island of Japan, Alaska, the Canadian Cordillera, and the U.S.A. Pacific Northwest in the last few decades. Geologic mapping suggests that most of this region can be interpreted as a collage of fault-bounded tectonostratigraphic terranes that were accreted onto continental margins around the Circum-

  2. Morphologic, Topographic, and Thermal Analysis of Slope Streaks on Mars

    Science.gov (United States)

    Aharonson, O.; Schorghofer, N.; Khatiwala, S.; Richardson, M. I.

    2002-12-01

    Surfaces containing features known as slope streaks are common on Mars in regions where thermal-inertia is low and steep slopes are frequent. We have recently compiled a catalog of slope streak images and identified previously unrecognized correlations with surface properties. Building on this work, we analyze data from Mars Orbiter Camera, from Mars Orbiter Laser Altimeter, and from the Thermal Emission Imaging System instrument on board Mars Odyssey, to constrain the physical properties and thermal conditions at the specific sites where slope streaks are forming. A number of proposed theories explaining the formation mechanism of slope streaks can be tested using new data, including an exciting possibility of the potential role of a water phase-transition.

  3. Determination Of Slope Instability Using Spatially Integrated Mapping Framework

    Science.gov (United States)

    Baharuddin, I. N. Z.; Omar, R. C.; Roslan, R.; Khalid, N. H. N.; Hanifah, M. I. M.

    2016-11-01

    The determination and identification of slope instability are often rely on data obtained from in-situ soil investigation work where it involves the logistic of machineries and manpower, thus these aspects may increase the cost especially for remote locations. Therefore a method, which is able to identify possible slope instability without frequent ground walkabout survey, is needed. This paper presents the method used in prediction of slope instability using spatial integrated mapping framework which applicable for remote areas such as tropical forest and natural hilly terrain. Spatial data such as geology, topography, land use map, slope angle and elevation were used in regional analysis during desktop study. Through this framework, the occurrence of slope instability was able to be identified and was validate using a confirmatory site- specific analysis.

  4. Changes Over a Martian Year -- New Dark Slope Streaks in Lycus Sucli

    Science.gov (United States)

    2001-01-01

    Now in its Extended Mission, Mars Global Surveyor (MGS) is into its second Mars year of systematic observations of the red planet. With the Extended Mission slated to run through April 2002, the Mars Orbiter Camera (MOC) is being used, among other things, to look for changes that have occurred in the past martian year. Because Mars is farther from the Sun than Earth, its year is longer--about 687 Earth days.The two pictures shown here cover the same portion of Lycus Sulci, a rugged, ridged terrain north of the giant Olympus Mons volcano. The interval between the pictures span 92% of a martian year (August 2, 1999 to April 27, 2001). Dark streaks considered to result from the avalanching of dry, fine, bright dust are seen in both images. The disruption of the surface by the avalanching materials is thought to cause them to appear darker than their surroundings, just as the 1997 bouncing of Mars Pathfinder's airbags and the tire tracks made by the Sojourner rover left darkened markings indicating where the martian soil had been disrupted and disturbed. The arrows in the April 2001 picture indicate eight new streaks that formed on these slopes in Lycus Sulci since August 1999. These observations suggest that a new streak forms approximately once per martian year per kilometer (about 0.62 miles) along a slope.In both images, north is toward the top/upper right and sunlight illuminates each from the left. Dark (as well bright) slope streaks are most common in the dust-covered martian regions of Tharsis, Arabia, and Elysium.

  5. Effect of Slope Positions on Physicochemical Properties of Soils Located on a Toposequence in Deilaman Area of Guilan Province

    Directory of Open Access Journals (Sweden)

    P. Mohajeri

    2016-10-01

    Full Text Available Introduction: Topography is one of the most important factors of soil formation and evolution. Soil properties vary spatially and are influenced by some environmental factors such as landscape features, including topography, slope aspect and position, elevation, climate, parent material and vegetation. Variations in landscape features can influence many phenomena and ecological processes including soil nutrients and water interactions. This factor affects soil properties by changing the altitude, steepness and slope direction of lands. In spite of the importance of understanding the variability of soils for better management, few studies have been done to assess the quality of soils located on a toposequence and most of these studies include just pedological properties. The aim of this study was to investigate physical and chemical properties of soils located on different slope positions and different depths of a toposequence in Deilaman area of Gilan province, that located in north of Iran. Materials and Methods: The lands on toposequence that were same in climate, parent material, vegetation and time factors but topographical factor was different, were divided into five sections including steep peak, shoulder slope, back slope, foot slope and toe slope. In order to topsoil sampling, transverse sections of this toposequence were divided into three parts lengthways, each forming one replicate or block. 10*10 square was selected and after removing a layer of undecomposed organic residues such as leaf litter, three depths of 0 to 20, 20 to 40 and 40 to60 cm soil samples were collected. physical and chemical characteristics such as soil texture, bulk density, aggregate stability, percent of organic matter, cation exchange capacity, available phosphorous and total nitrogen were measured. Results and Discussion: The results showed that, because of high organic matter content and fine textured soils on the lower slope positions including foot slope

  6. Fargo, North Dakota, USA

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Annotated version Click on the image for high resolution TIFF file Why does Fargo flood? The Red River of the North, which forms the border between North Dakota and Minnesota, has a long history of severe floods. Major floods include those of 1826, 1897, 1950, 1997, and now 2009. The 1997 flood caused billions of dollars of damage, with greatest impact to the city of Grand Forks, north of and downstream from Fargo. The 2009 flood, which has primarily impacted Fargo, appears to have peaked early on March 28. Several factors combine to cause floods. Obviously, rainfall and snowmelt rates (and their geographic distribution) are the fundamental variables that create flooding in some years and not others. But the repetition of flooding in Fargo (and areas downstream), rather than in adjacent regions, can be attributed largely to its topographic setting and geologic history. The formation of landforms in the geologic past is often interpretable from digital topographic data, such as that supplied by the Shuttle Radar Topography Mission (SRTM). This image, covering parts of North Dakota, Minnesota, and South Dakota, displays ground elevation as brightness (higher is brighter) plus has simulated shading (with illumination from the north) to enhance topographic detail such as stream channels, ridges, and cliffs. The Red River of the North is the only major river that flows northward from the United States into Canada. In this scene it flows almost straight north from Fargo. North of this image it continues past the city of Winnipeg, Manitoba, and into Lake Winnipeg, which in turn drains to Hudson Bay. In the United States, the river lies in a trough that was shaped by continental glaciers that pushed south from Canada during the Pleistocene epoch, up to about 10,000 years ago. This trough is about 70 km (45 miles) wide and tens of meters (very generally about 100 feet) deep. Here near Fargo it lies on the east side of a much

  7. Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk, Rishikesh, India

    Directory of Open Access Journals (Sweden)

    Tariq Siddique

    2015-10-01

    Full Text Available The road network in the Himalayan terrain, connecting remote areas either in the valleys or on the hill slopes, plays a pivotal role in socio-economic development of India. The planning, development and even maintenance of road and rail networks in such precarious terrains are always a challenging task because of complexities posed by topography, geological structures, varied lithology and neotectonics. Increasing population and construction of roads have led to destabilisation of slopes, thus leading to mass wasting and movement, further aggravation due to recent events of cloud bursts and unprecedented flash floods. Vulnerability analysis of slopes is an important component for the “Landslide Hazard Assessment” and “Slope Mass Characterisation” guide planners to predict and choose suitable ways for construction of roads and other engineering structures. The problem of landslides along the national highway-58 (NH-58 from Rishikesh to Devprayag is a common scene. The slopes along the NH-58 between Jonk and Rishikesh were investigated, which experienced very heavy traffic especially from March to August due to pilgrimage to Kedarnath shrine. On the basis of slope mass rating (SMR investigation, the area falls in stable class, and landslide susceptibility score (LSS values also indicate that the slopes under investigation fall in low to moderate vulnerability to landslide. More attentions should be paid to the slopes to achieve greater safe and economic benefits along the highway.

  8. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    The problem of determining the bearing capacity of a strip foundation located near a slope of infinite height has been dealt with by several authors. Very often in practical problems the slope is of limited height, and furthermore the resulting load may be inclined at an angle to the horizontal, ...

  9. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

    Science.gov (United States)

    Török, Ákos; Barsi, Árpád; Bögöly, Gyula; Lovas, Tamás; Somogyi, Árpád; Görög, Péter

    2018-02-01

    Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE-WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).

  10. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

    Directory of Open Access Journals (Sweden)

    Á. Török

    2018-02-01

    Full Text Available Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System was used to collect images which were processed by Pix4D mapper (structure from motion technology to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS with the use of seven ground control points. The obtained digital surface model (DSM was processed (vegetation removal and the derived digital terrain model (DTM allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method. Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE–WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS.

  11. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  12. Study on the response of unsaturated soil slope based on the effects of rainfall intensity and slope angle

    Science.gov (United States)

    Ismail, Mohd Ashraf Mohamad; Hamzah, Nur Hasliza

    2017-07-01

    Rainfall has been considered as the major cause of the slope failure. The mechanism leading to slope failures included the infiltration process, surface runoff, volumetric water content and pore-water pressure of the soil. This paper describes a study in which simulated rainfall events were used with 2-dimensional soil column to study the response of unsaturated soil behavior based on different slope angle. The 2-dimensional soil column is used in order to demonstrate the mechanism of the slope failure. These unsaturated soil were tested with four different slope (15°, 25°, 35° and 45°) and subjected to three different rainfall intensities (maximum, mean and minimum). The following key results were obtained: (1) the stability of unsaturated soil decrease as the rainwater infiltrates into the soil. Soil that initially in unsaturated state will start to reach saturated state when rainwater seeps into the soil. Infiltration of rainwater will reduce the matric suction in the soil. Matric suction acts in controlling soil shear strength. Reduction in matric suction affects the decrease in effective normal stress, which in turn diminishes the available shear strength to a point where equilibrium can no longer be sustained in the slope. (2) The infiltration rate of rainwater decreases while surface runoff increase when the soil nearly achieve saturated state. These situations cause the soil erosion and lead to slope failure. (3) The steepness of the soil is not a major factor but also contribute to slope failures. For steep slopes, rainwater that fall on the soil surface will become surface runoff within a short time compare to the water that infiltrate into the soil. While for gentle slopes, water that becomes surface runoff will move slowly and these increase the water that infiltrate into the soil.

  13. Tissue Distribution of Polychlorinated Biphenyls and Organochlorine Pesticides and Potential Toxicity to Alaskan Northern Fur Seals Assessed Using PCBs Congener Specific Mode of Action Schemes

    Science.gov (United States)

    The concentrations of 145 polychlorinated biphenyl (PCB) congeners were measured using gas chromatography-ion trap mass spectrometry in 8 different tissues (blubber, brain, heart, kidney, liver, lung, muscle, and reproductive tissues) of 10 Alaskan northern fur seals. The mean concentrations of bot...

  14. Martian slope streaks as plausible indicators of transient water activity.

    Science.gov (United States)

    Bhardwaj, Anshuman; Sam, Lydia; Martín-Torres, F Javier; Zorzano, María-Paz; Fonseca, Ricardo M

    2017-08-01

    Slope streaks have been frequently observed in the equatorial, low thermal inertia and dusty regions of Mars. The reason behind their formation remains unclear with proposed hypotheses for both dry and wet mechanisms. Here, we report an up-to-date distribution and morphometric investigation of Martian slope streaks. We find: (i) a remarkable coexistence of the slope streak distribution with the regions on Mars with high abundances of water-equivalent hydrogen, chlorine, and iron; (ii) favourable thermodynamic conditions for transient deliquescence and brine development in the slope streak regions; (iii) a significant concurrence of slope streak distribution with the regions of enhanced atmospheric water vapour concentration, thus suggestive of a present-day regolith-atmosphere water cycle; and (iv) terrain preferences and flow patterns supporting a wet mechanism for slope streaks. These results suggest a strong local regolith-atmosphere water coupling in the slope streak regions that leads to the formation of these fluidised features. Our conclusions can have profound astrobiological, habitability, environmental, and planetary protection implications.

  15. Soil erosion processes on sloping land using REE tracer

    International Nuclear Information System (INIS)

    Shen Zhenzhou; Liu Puling; Yang Mingyi; Lian Zhenlong; Ju Tongjun; Yao Wenyi; Li Mian

    2007-01-01

    Sheet erosion is the main performance in the slope soil erosion process at the primary stage of natural rainfall. For three times of rainfall during experiment, the ratios of sheet erosion to total erosion account for 71%, 48% and 49% respectively, which showed that the sloping erosion was still at the primary stage from sheet erosion to rill erosion. With the rainfall going, the rill erosion amount increase. It showed that soil erosion was changing from sheet erosion to rill erosion. The sources of sediment from different sections of the plot were analyzed, and the results indicated that whatever the sheet erosion changed, the ratio erosion of upper part of surface soil was always lower than 10%. Sheet erosion came mainly from the lower section of surface soil. With the ratios to the amount of total rill erosion changes, the rill erosion amount of each section regularly changes too. The general conclusion is that when the rainfall ends, relative erosion of different slope element to the foot of slope is: 1 meter away accounts for 16%, 2-4 meters away is 6% and 5-9 meters away is 3%. The ratio of rill erosion amount of these three slope element is 5:2:1, which shows the rill erosion amount are mainly from the slope element of 4 meters from the foot of slope. (authors)

  16. Intraspecific evolutionary relationships among peregrine falcons in western North American high latitudes.

    Directory of Open Access Journals (Sweden)

    Sandra L Talbot

    Full Text Available Subspecies relationships within the peregrine falcon (Falco peregrinus have been long debated because of the polytypic nature of melanin-based plumage characteristics used in subspecies designations and potential differentiation of local subpopulations due to philopatry. In North America, understanding the evolutionary relationships among subspecies may have been further complicated by the introduction of captive bred peregrines originating from non-native stock, as part of recovery efforts associated with mid 20th century population declines resulting from organochloride pollution. Alaska hosts all three nominal subspecies of North American peregrine falcons-F. p. tundrius, anatum, and pealei-for which distributions in Alaska are broadly associated with nesting locales within Arctic, boreal, and south coastal maritime habitats, respectively. Unlike elsewhere, populations of peregrine falcon in Alaska were not augmented by captive-bred birds during the late 20th century recovery efforts. Population genetic differentiation analyses of peregrine populations in Alaska, based on sequence data from the mitochondrial DNA control region and fragment data from microsatellite loci, failed to uncover genetic distinction between populations of peregrines occupying Arctic and boreal Alaskan locales. However, the maritime subspecies, pealei, was genetically differentiated from Arctic and boreal populations, and substructured into eastern and western populations. Levels of interpopulational gene flow between anatum and tundrius were generally higher than between pealei and either anatum or tundrius. Estimates based on both marker types revealed gene flow between augmented Canadian populations and unaugmented Alaskan populations. While we make no attempt at formal taxonomic revision, our data suggest that peregrine falcons occupying habitats in Alaska and the North Pacific coast of North America belong to two distinct regional groupings-a coastal grouping

  17. Intraspecific evolutionary relationships among peregrine falcons in western North American high latitudes

    Science.gov (United States)

    Talbot, Sandra L.; Sage, Kevin; Sonsthagen, Sarah A.; Gravley, Meg C.; Swem, Ted; Williams, Jeffrey C.; Longmire, Jonathan L.; Ambrose, Skip; Flamme, Melanie J; Lewis, Stephen B.; Phillips, Laura M.; Anderson, Clifford; White, Clayton M

    2017-01-01

    Subspecies relationships within the peregrine falcon (Falco peregrinus) have been long debated because of the polytypic nature of melanin-based plumage characteristics used in subspecies designations and potential differentiation of local subpopulations due to philopatry. In North America, understanding the evolutionary relationships among subspecies may have been further complicated by the introduction of captive bred peregrines originating from non-native stock, as part of recovery efforts associated with mid 20th century population declines resulting from organochloride pollution. Alaska hosts all three nominal subspecies of North American peregrine falcons–F. p. tundrius, anatum, and pealei–for which distributions in Alaska are broadly associated with nesting locales within Arctic, boreal, and south coastal maritime habitats, respectively. Unlike elsewhere, populations of peregrine falcon in Alaska were not augmented by captive-bred birds during the late 20th century recovery efforts. Population genetic differentiation analyses of peregrine populations in Alaska, based on sequence data from the mitochondrial DNA control region and fragment data from microsatellite loci, failed to uncover genetic distinction between populations of peregrines occupying Arctic and boreal Alaskan locales. However, the maritime subspecies, pealei, was genetically differentiated from Arctic and boreal populations, and substructured into eastern and western populations. Levels of interpopulational gene flow between anatum and tundrius were generally higher than between pealei and either anatum or tundrius. Estimates based on both marker types revealed gene flow between augmented Canadian populations and unaugmented Alaskan populations. While we make no attempt at formal taxonomic revision, our data suggest that peregrine falcons occupying habitats in Alaska and the North Pacific coast of North America belong to two distinct regional groupings–a coastal grouping

  18. Slope Deformation Prediction Based on Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Lei JIA

    2013-07-01

    Full Text Available This paper principally studies the prediction of slope deformation based on Support Vector Machine (SVM. In the prediction process,explore how to reconstruct the phase space. The geological body’s displacement data obtained from chaotic time series are used as SVM’s training samples. Slope displacement caused by multivariable coupling is predicted by means of single variable. Results show that this model is of high fitting accuracy and generalization, and provides reference for deformation prediction in slope engineering.

  19. 76 FR 56789 - Call for Nominations: North Slope Science Initiative, Science Technical Advisory Panel, Alaska

    Science.gov (United States)

    2011-09-14

    ... Ocean Energy, Management, Regulations, and Enforcement, and National Marine Fisheries Service; the... engineering, geology, botany, hydrology, limnology, habitat biology, wildlife biology, biometrics, sociology, cultural anthropology, economics, ornithology, oceanography, fisheries biology, and climatology. The duties...

  20. Cosmic-Ray Moisture Probe on North Slope of Alaska Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Desilets, Darin [Hydroinnova LLC

    2016-06-15

    In September of 2014 a wide-area snow monitoring device was installed at the U.S. Department of Energy (DOE)’s Barrow, Alaska Atmospheric Radiation Measurement (ARM) Climate Research Facility site. The device is special in that it uses measurements of cosmic-ray neutrons as a proxy for snow water equivalent (SWE) depth. A unique characteristic of the technology is that it integrates over a wide area (as much as 40 ha), in contrast to conventional ground-based technologies, which essentially give point samples. Conventional point-scale technologies are problematic in the Arctic, both because extreme weather conditions are taxing on equipment, and because point measurements can fail to accurately characterize the average SWE over a larger area, even when excellent precision is obtained. The sensor installed in Barrow is, by far, the northernmost of a constellation of sites that makeup the U.S. COsmic ray Soil Moisture Observing System (COSMOS). The sensor is used for SWE measurements in winter and soil moisture measurements in summer. The ability of this type of sensor to operate in the Arctic had not been verified until now. The cosmic-ray sensor was installed on a tripod located approximately 150 m south of the ARM User Facility (Figure 1), and within boundaries of land managed by the ARM Facility. The sensor consists of both “bare” and “moderated” channels, where the moderated channel is the primary output used to calculate SWE. A QDL2100 data logger with pressure sensor was located inside of the User Facility, and a Campbell CS215 temperature and humidity sensor was attached to a rail on the upper deck of the User Facility, to enable near-real-time absolute humidity corrections to the data. The cosmic-ray sensors are connected to the data logger using an armored Cat5e cable that lies on top of the tundra. Data are retrieved hourly via Iridium satellite link.

  1. Pre-ABoVE: Arctic Vegetation Plots in Flux Tower Footprints, North Slope Alaska, 2014

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides vegetation, environmental, and soil data collected from plots located in the footprints of eddy covariance flux towers along a 300 km...

  2. Pre-ABoVE: Ground-penetrating Radar Measurements of ALT on the Alaska North Slope

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes estimates of permafrost Active Layer Thickness (ALT; cm), and calculated uncertainties, derived using a ground-penetrating radar (GPR) system...

  3. Hybrid image classification technique for land-cover mapping in the Arctic tundra, North Slope, Alaska

    Science.gov (United States)

    Chaudhuri, Debasish

    Remotely sensed image classification techniques are very useful to understand vegetation patterns and species combination in the vast and mostly inaccessible arctic region. Previous researches that were done for mapping of land cover and vegetation in the remote areas of northern Alaska have considerably low accuracies compared to other biomes. The unique arctic tundra environment with short growing season length, cloud cover, low sun angles, snow and ice cover hinders the effectiveness of remote sensing studies. The majority of image classification research done in this area as reported in the literature used traditional unsupervised clustering technique with Landsat MSS data. It was also emphasized by previous researchers that SPOT/HRV-XS data lacked the spectral resolution to identify the small arctic tundra vegetation parcels. Thus, there is a motivation and research need to apply a new classification technique to develop an updated, detailed and accurate vegetation map at a higher spatial resolution i.e. SPOT-5 data. Traditional classification techniques in remotely sensed image interpretation are based on spectral reflectance values with an assumption of the training data being normally distributed. Hence it is difficult to add ancillary data in classification procedures to improve accuracy. The purpose of this dissertation was to develop a hybrid image classification approach that effectively integrates ancillary information into the classification process and combines ISODATA clustering, rule-based classifier and the Multilayer Perceptron (MLP) classifier which uses artificial neural network (ANN). The main goal was to find out the best possible combination or sequence of classifiers for typically classifying tundra type vegetation that yields higher accuracy than the existing classified vegetation map from SPOT data. Unsupervised ISODATA clustering and rule-based classification techniques were combined to produce an intermediate classified map which was used as an input to a Multilayer Perceptron (MLP) classifier. The result from the MLP classifier was compared to the previous classified map and for the pixels where there was a disagreement for the class allocations, the class having a higher kappa value was assigned to the pixel in the final classified map. The results were compared to standard classification techniques: simple unsupervised clustering technique and supervised classification with Feature Analyst. The results indicated higher classification accuracy (75.6%, with kappa value of .6840) for the proposed hybrid classification method than the standard classification techniques: unsupervised clustering technique (68.3%, with kappa value of 0.5904) and supervised classification with Feature Analyst (62.44%, with kappa value of 0.5418). The results were statistically significant at 95% confidence level. Keywords: Arctic tundra, hybrid classification, artificial neural network

  4. Pre-ABoVE: Arctic Vegetation Plots, Willow Communities, North Slope, Alaska, 1997

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides environmental, soil, and vegetation data collected in July and August 1997 from 85 study plots in willow shrub communities located along a...

  5. Evaluation of the biodegradation of Alaska North Slope oil in microcosms using the biodegradation model BIOB

    Directory of Open Access Journals (Sweden)

    Jagadish eTorlapati

    2014-05-01

    Full Text Available We present the details of a numerical model, BIOB that is capable of simulating the biodegradation of oil entrapped in the sediment. The model uses Monod kinetics to simulate the growth of bacteria in the presence of nutrients and the subsequent consumption of hydrocarbons. The model was used to simulate experimental results of Exxon Valdez oil biodegradation in laboratory columns (Venosa et al. (2010. In that study, samples were collected from three different islands: Eleanor Island (EL107, Knight Island (KN114A, and Smith Island (SM006B, and placed in laboratory microcosms for a duration of 168 days to investigate oil bioremediation through natural attenuation and nutrient amendment. The kinetic parameters of the BIOB model were estimated by fitting to the experimental data using a parameter estimation tool based on Genetic Algorithms (GA. The parameter values of EL107 and KN114A were similar whereas those of SM006B were different from the two other sites; in particular biomass growth at SM006B was four times slower than at the other two islands. Grain size analysis from each site revealed that the specific surface area per unit mass of sediment was considerably lower at SM006B, which suggest that the surface area of sediments is a key control parameter for microbial growth in sediments. Comparison of the BIOB results with exponential decay curves fitted to the data indicated that BIOB provided better fit for KN114A and SM006B in nutrient amended treatments, and for EL107 and KN114A in natural attenuation. In particular, BIOB was able to capture the initial slow biodegradation due to the lag phase in microbial growth. Sensitivity analyses revealed that oil biodegradation at all three locations were sensitive to nutrient concentration whereas SM006B was sensitive to initial biomass concentration due to its slow growth rate. Analyses were also performed to compare the half-lives of individual compounds with the decay rate of the overall PAH.

  6. Pre-ABoVE: Arctic Vegetation Plots, Frost Boil Sites, North Slope, Alaska, 2000-2006

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set describes the environment, soil, and vegetation on nonsorted circles and earth hummocks at seven study sites along a N-S-transect from the Arctic Ocean...

  7. ABoVE: Gridded 30-m Aboveground Biomass, Shrub Dominance, North Slope, AK, 2007-2016

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset includes 30-m gridded estimates of total plant aboveground biomass (AGB), the shrub AGB, and the shrub dominance (shrub/plant AGB) for non-water...

  8. 2009 Aero-Metric Inc. Topographic LiDAR: North Slope Coastal Alaska

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This delivery contains point cloud data in LAS 1.2 format, with Absolute GPS Timestamps. No classification has been completed on these data. The nominal point...

  9. Assessment of the Phototoxicity of Weathered Alaska North Slope Crude Oil to Juvenile Pink Salmon

    Science.gov (United States)

    Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assesse...

  10. Volcanic Ash on Slopes of Karymsky

    Science.gov (United States)

    2007-01-01

    A volcanic eruption can produce gases, lava, bombs of rock, volcanic ash, or any combination of these elements. Of the volcanic products that linger on the land, most of us think of hardened lava flows, but volcanic ash can also persist on the landscape. One example of that persistence appeared on Siberia's Kamchatka Peninsula in spring 2007. On March 25, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the area around the Karymsky Volcano. In this image, volcanic ash from earlier eruptions has settled onto the snowy landscape, leaving dark gray swaths. The ash stains are confined to the south of the volcano's summit, one large stain fanning out toward the southwest, and another toward the east. At first glance, the ash stain toward the east appears to form a semicircle north of the volcano and sweep back east. Only part of this dark shape, however, is actually volcanic ash. Near the coast, the darker color may result from thicker vegetation. Similar darker coloring appears to the south. Volcanic ash is not really ash at all, but tiny, jagged bits of rock and glass. These jagged particles pose serious health risks to humans and animals who might inhale them. Likewise, the ash poses hazards to animals eating plants that have been coated with ash. Because wind can carry volcanic ash thousands of kilometers, it poses a more far-reaching hazard than other volcanic ejecta. Substantial amounts of ash can even affect climate by blocking sunlight. Karymsky is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. It is one of many active volcanoes on Russia's Kamchatka Peninsula, which is part of the 'Ring of Fire' around the Pacific Rim. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  11. Neogene molluscan stages of the West Coast of North America

    Science.gov (United States)

    Marincovich, L.

    1984-01-01

    Neogene marine sediments of the West Coast of North America were deposited in a series of widely spaced basins that extended geographically from the western and northern Gulf of Alaska (60??N) to southern California (33??N). Rich molluscan faunas occur extensively throughout these deposits and form the basis for biostratigraphic schemes that are useful for correlating within and between individual basins. Early biostratigraphic work was concerned with faunas from particular horizons and with the stratigraphic range of diverse taxa, such as Pecten and Turritella, without reference to other fossil groups. Succeeding work increasingly dealt with the relationships of molluscan zones to benthic and, later, planktonic foraminiferal stages. In recent years the age limits of Neogene molluscan stages have become better documented by reference to planktonic microfossils from dated DSDP cores and onshore faunas. Neogene molluscan faunas from California, the Pacific Northwest states (Oregon and Washington), and southern Alaska have been treated separately due to differences in faunal composition and geographic isolation. As a result, a different biostratigraphic sequence has been described for each region. Pacific Northwest stages have been formally named and defined, and their names are also used informally for Alaskan faunas. California Neogene stages were proposed early in this century, are in need of redescription, and their usage is informal. Precise correlations between the three regional sequences have not yet been achieved, due to the low number of co-occurring species and the general lack of planktonic microfossils in these largely shallow-water faunas. The objectives of ongoing research include: fuller documentation of the faunas of California and Pacific Northwest stages; formal description of California stages; improved correlation between regional stage sequences; refinement of age estimates for stage boundaries; and, establishment of Neogene stages for Alaskan

  12. Increasing fire severity, alternate successional trajectories, and the carbon balance of Alaskan boreal forests

    Science.gov (United States)

    Mack, M. C.; Alexander, H. D.; Jean, M.; Melvin, A. M.; Johnstone, J. F.

    2016-12-01

    Climate-sensitive disturbances, such as wildfire, can feed back positively to climate warming via the carbon (C) cycle if C released by disturbance is not replaced over post-fire succession. In boreal forests, burning of carbon in deep organic soils is not only an important determinate of ecosystem element balance over the disturbance cycle, but also sets the conditions that control plant recruitment, species dominance and successional trajectory. Species dominance, in turn, has the potential to exert strong control over the plant-soil-microbial feedbacks that determine C and nutrient coupling, C storage, and ultimately, replacement of combusted C. We examined the consequences of increasing fire severity for C balance and C and nitrogen (N) coupling in Alaskan boreal forests. We estimated combustion losses in 90 black spruce (conifer) stands that burned in 2004. Over the next decade, we followed natural tree seedling establishment in these stands and used seedling species dominance identify conifer versus deciduous successional trajectories. We assembled data from 120 stands that varied in time after fire and successional trajectory, and estimated C and N dynamics across 150 years of post-fire succession for each trajectory. Conifer stands that burned with high severity transitioned to deciduous tree dominance after fire. These stands had smaller ecosystem pools of C and N before fire, lost a larger proportion of these pools during the fire, and began succession with smaller residual pools than stands that returned to conifer dominance after fire. Over secondary succession, deciduous stands accumulated about 10 times more carbon in aboveground biomass than conifer stands. Belowground biomass and soil carbon accumulation, by contrast, was about three times higher in the black spruce stands than in deciduous stands. As a result, net ecosystem C accumulation over the 100 year inter-fire interval was three times higher in deciduous stands than in coniferous stands

  13. Brucella Antibodies in Alaskan True Seals and Eared Seals—Two Different Stories

    Directory of Open Access Journals (Sweden)

    Ingebjørg H. Nymo

    2018-01-01

    Full Text Available Brucella pinnipedialis was first isolated from true seals in 1994 and from eared seals in 2008. Although few pathological findings have been associated with infection in true seals, reproductive pathology including abortions, and the isolation of the zoonotic strain type 27 have been documented in eared seals. In this study, a Brucella enzyme-linked immunosorbent assay (ELISA and the Rose Bengal test (RBT were initially compared for 206 serum samples and a discrepancy between the tests was found. Following removal of lipids from the serum samples, ELISA results were unaltered while the agreement between the tests was improved, indicating that serum lipids affected the initial RBT outcome. For the remaining screening, we used ELISA to investigate the presence of Brucella antibodies in sera of 231 eared and 1,412 true seals from Alaskan waters sampled between 1975 and 2011. In eared seals, Brucella antibodies were found in two Steller sea lions (Eumetopias jubatus (2% and none of the 107 Northern fur seals (Callorhinus ursinus. The low seroprevalence in eared seals indicate a low level of exposure or lack of susceptibility to infection. Alternatively, mortality due to the Brucella infection may remove seropositive animals from the population. Brucella antibodies were detected in all true seal species investigated; harbor seals (Phoca vitulina (25%, spotted seals (Phoca largha (19%, ribbon seals (Histriophoca fasciata (16%, and ringed seals (Pusa hispida hispida (14%. There was a low seroprevalence among pups, a higher seroprevalence among juveniles, and a subsequent decreasing probability of seropositivity with age in harbor seals. Similar patterns were present for the other true seal species; however, solid conclusions could not be made due to sample size. This pattern is in accordance with previous reports on B. pinnipedialis infections in true seals and may suggest environmental exposure to B. pinnipedialis at the juvenile stage, with a

  14. Site-Specific Bluff Recession Rates Measured on the Alaskan Beaufort Sea Coast

    Science.gov (United States)

    Richmond, B.; Gadd, P.; Crowell, W.

    2017-12-01

    OverviewThe effects of climate change are being studied globally with coastal erosion in Arctic regions of particular concern. In support of Hilcorp Alaska's Northstar Development, short- and long-term bluff recession rates have been documented at a pipeline shore crossing located in Gwydyr Bay on the Alaskan Beaufort Sea coast. These data are presented, along with the predominant forcing mechanisms, and compared to local and regional recession rates recently published by the U.S. Geological Survey (USGS). Arctic Bluff RecessionCoastal retreat along the northern coast of Alaska occurs at two different rates: infrequent, but rapid erosion induced by strong westerly storms, and seasonal retreat related to thawing and sediment removal under more moderate wave conditions. Variability in the rate of bluff retreat is related to a number of factors, including bluff composition (ice content and sediment type), existence of a fronting beach, and wave exposure. Measured Bluff Recession at the Northstar Pipeline Shore CrossingThe location of the Northstar Development pipeline shore crossing was chosen based on analysis of historical aerial photos acquired between 1949 and 1996. Over this 47-year period, the average annualized rate of bluff retreat in the study area ranged from 1.6 to 3.0 ft/yr. Beginning in 1996, ground-based shoreline monitoring surveys have been conducted along the bluff and ten shore-perpendicular transects at the site. The rates of bluff retreat derived from the survey data have been modest, ranging from no change to 5.8 ft/yr. The monitoring surveys indicate that waves and currents erode the bluffs by direct impact only during infrequent, but strong westerly storms that promote a short-term rise in sea level (storm surge). The more prevalent easterly storms can cause set-down, or reduction in the sea level which limits direct wave impact on the bluff, thereby decreasing the potential for wave induced erosion. Comparative StudiesRecent studies conducted

  15. Canyon-confined pockmarks on the western Niger Delta slope

    Science.gov (United States)

    Benjamin, Uzochukwu; Huuse, Mads; Hodgetts, David

    2015-07-01

    Fluid flow phenomena in the deepwater Niger Delta are important for the safe and efficient exploration, development and production of hydrocarbons in the area. Utilizing 3D seismic data from the western Niger Delta slope, we have identified pockmarks that are confined within a NE-SW oriented submarine canyon system that has been active since the early Quaternary. The pockmarks, subdivided into 'canyon-margin' pockmarks and 'intra-canyon' pockmarks, on the basis of their plan-form distribution patterns, are found to be spatially and stratigraphically related to stratigraphic discontinuities created by erosion cuts associated with the submarine canyon system. We infer that stratigraphic discontinuities provided pathways for fluid migration within the buried canyon system, allowing fluids from deeper parts of the basin to reach the seafloor as indicated by abundant pockmarks above the partly buried canyon. The transportation of fluids from deeper parts of the basin into the buried segment of the canyon system was facilitated by carrier beds expressed as high amplitude reflection packages and by extensional normal faults. The prevalence of the 'canyon margin' pockmarks over the 'intra-canyon' pockmarks is attributed to the direct connection of the buried canyon margins with truncated reservoir facies in hydraulic connection with deeper reservoir facies. The formation of the 'intra-canyon' pockmarks is interpreted to have been limited by fluid flow disconnection often caused by stratigraphic alternation of sand-rich and shale-rich channel deposits that constitute the canyon fill. Muddy canyon fill units act as baffles to fluid flow, while connected sandy infill units constitute pathways for fluid migration. Occurrence of pockmarks throughout the length of the submarine canyon system is an indication of shallow fluid flow within buried reservoir facies. Systematic alignment of seafloor pockmarks are clues to buried reservoirs and provide insights into reservoir

  16. Thermomechanical forcing of deep rock slope deformation: 2. The Randa rock slope instability

    Science.gov (United States)

    Gischig, Valentin S.; Moore, Jeffrey R.; Evans, Keith F.; Amann, Florian; Loew, Simon

    2011-12-01

    Deformation monitoring between 2004 and 2011 at the rock slope instability above Randa (Switzerland) has revealed an intriguing seasonal trend. Relative dislocation rates across active fractures increase when near-surface rock temperatures drop in the fall and decrease after snowmelt as temperatures rise. This temporal pattern was observed with different monitoring systems at the ground surface and at depths up to 68 m, and represents the behavior of the entire instability. In this paper, the second of two companion pieces, we interpret this seasonal deformation trend as being controlled by thermomechanical (TM) effects driven by near-surface temperature cycles. While Part 1 of this work demonstrated in a conceptual manner how TM effects can drive deep rock slope deformation and progressive failure, we present here in Part 2 a case study where temperature-controlled deformation trends were observed in a natural setting. A 2D discrete-element numerical model is employed, which allows failure along discontinuities and successfully reproduces the observed kinematics of the Randa instability. By implementing simplified ground surface temperature forcing, model results were able to reproduce the observed deformation pattern, and TM-induced displacement rates and seasonal amplitudes in the model are of the same order of magnitude as measured values. Model results, however, exhibit spatial variation in displacement onset times while field measurements show more synchronous change. Additional heat transfer mechanisms, such as fracture ventilation, likely create deviations from the purely transient-conductive temperature field modeled. We suggest that TM effects are especially important at Randa due to the absence of significant groundwater within the unstable rock mass.

  17. Short-Term Impacts of the Air Temperature on Greening and Senescence in Alaskan Arctic Plant Tundra Habitats

    Directory of Open Access Journals (Sweden)

    Jeremy L. May

    2017-12-01

    Full Text Available Climate change is warming the temperatures and lengthening the Arctic growing season with potentially important effects on plant phenology. The ability of plant species to acclimate to changing climatic conditions will dictate the level to which their spatial coverage and habitat-type dominance is different in the future. While the effect of changes in temperature on phenology and species composition have been observed at the plot and at the regional scale, a systematic assessment at medium spatial scales using new noninvasive sensor techniques has not been performed yet. At four sites across the North Slope of Alaska, changes in the Normalized Difference Vegetation Index (NDVI signal were observed by Mobile Instrumented Sensor Platforms (MISP that are suspended over 50 m transects spanning local moisture gradients. The rates of greening (measured in June and senescence (measured in August in response to the air temperature was estimated by changes in NDVI measured as the difference between the NDVI on a specific date and three days later. In June, graminoid- and shrub-dominated habitats showed the greatest rates of NDVI increase in response to the high air temperatures, while forb- and lichen-dominated habitats were less responsive. In August, the NDVI was more responsive to variations in the daily average temperature than spring greening at all sites. For graminoid- and shrub-dominated habitats, we observed a delayed decrease of the NDVI, reflecting a prolonged growing season, in response to high August temperatures. Consequently, the annual C assimilation capacity of these habitats is increased, which in turn may be partially responsible for shrub expansion and further increases in net summer CO2 fixation. Strong interannual differences highlight that long-term and noninvasive measurements of such complex feedback mechanisms in arctic ecosystems are critical to fully articulate the net effects of climate variability and climate change on

  18. Submarine slope failures due to pipe structure formation.

    Science.gov (United States)

    Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H

    2018-02-19

    There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

  19. Percent Agricultural Land Cover on Steep Slopes (Future)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Clearing land for agriculture tends to increase soil erosion. The amount of erosion is related to the steepness of the slope, farming methods used and soil type....

  20. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter....... The experimental results of measured loop-gain at different operating points are presented to validate the theoretical performance of the controller....

  1. Slope movements in Callejón de Huyalas, Peru

    Czech Academy of Sciences Publication Activity Database

    Vilímek, V.; Zapata, M. L.; Stemberk, Josef

    2003-01-01

    Roč. 35, supplementum (2003), s. 39-51 ISSN 0300-5402 Institutional research plan: CEZ:AV0Z3046908 Keywords : slope movements * natural hazards * Cordillera Blanca Subject RIV: DB - Geology ; Mineralogy

  2. Clay mineral distribution on the Kerala continental shelf and slope

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Nair, R.R.; Hashimi, N.H.

    minerals are quartz and feldspar. Kaolinite and gibbsite have low values on the outer shelf and high values on the inner shelf and slope, while illite increases in the offshore direction. However, montmorillonite behaves differently from others in having...

  3. Slope Stabilization Using Recycled Plastic Pins, Phase III.

    Science.gov (United States)

    2007-01-01

    A new technique for stabilizing surficial slope failures using recycled plastic reinforcing members has been developed. The : objective of the project described in this report has been to develop, evaluate, and document a technique for stabilization ...

  4. Probabilistic analysis algorithm for UA slope software program.

    Science.gov (United States)

    2013-12-01

    A reliability-based computational algorithm for using a single row and equally spaced drilled shafts to : stabilize an unstable slope has been developed in this research. The Monte-Carlo simulation (MCS) : technique was used in the previously develop...

  5. Landslide hazard on the slopes of Dabicho Ridge, Wondo Genet ...

    African Journals Online (AJOL)

    1996-06-18

    Landslide hazard on the slopes of Dabicho Ridge, Wondo Genet area: the case of June 18, 1996 event. Berhanu Temesgen, Mohammed Umer, Asfawossen Asrat, Ogbaghebriel Berakhi, Abayneh Ayele, Dramis Francesco, Metasebia Demissie ...

  6. Systems of pillarless working of adjacent, sloped and inclined seams

    Energy Technology Data Exchange (ETDEWEB)

    Batmanov, Yu.K.; Bakhtin, A.F.; Bulavka, E.I.

    1979-01-01

    An analysis is made (advantages and disadvantages) of existing and recommended (pillarless) systems of working adjacent, sloped, and inclined seams. The economic benefits, area and extent of those systems are indicated. 8 references, 4 figures.

  7. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    The problem of determining the bearing capacity of a strip foundation located near a slope of infinite height has been dealt with by several authors. Very often in practical problems the slope is of limited height, and furthermore the resulting load may be inclined at an angle to the horizontal......, and in such cases the bearing capacity of the footing cannot be found using the existing methods. The present work comprises finite element based upper- and lower-bound calculations, using the geotechnical software OptumG2 to investigate the effect of the slope height and horizontal forces on the total bearing...

  8. Slope Impacts on Concentrated Flow Hydraulics in Rangeland

    Science.gov (United States)

    Al-Hamdan, O. Z.; Pierson, F. B.; Williams, C. J.; Kormos, P. R.; Nearing, M. A.; Boll, J.

    2009-12-01

    Several studies have been conducted to describe rill or concentrated flow hydraulics. However, most of these studies used data obtained from either laboratory experiments or field sites located on gently sloping crop lands. The data sets in the few rangeland field studies conducted did not cover a variety of hillslope angles and generally focused on slope gradients less than 20%. The lack of studies with steeper slopes resulted in misinterpreting the slope gradient impact on concentrated flow hydraulics, as sites with different slopes have different soil and vegetation cover characteristics. This study examines the characteristics of rangeland concentrated flow hydraulics as a function of vegetation and ground cover using field experimental data from diverse vegetated rangeland sites of the western United States. These data span a wide range of slope angles (5.6%-65.8%), soil types, and vegetative cover. Many of the sites exhibit some degree of disturbance, such as wild fire, prescribed fire, tree mastication, and/or tree cutting. The data were divided into two sets, gently sloping (20%). Analyses were performed on each data set separately as well as on the combined data set. For the complete data set, concentrated flow occurred on less than 26% of the gently sloping plots and on more than 70% of the steep plots. The results showed that the Darcy-Weisbach roughness coefficient (f) had no significant correlation with vegetation and ground cover variables on the gently sloping sites. However, roughness coefficient f was positively correlated with vegetation and ground cover on steep rangelands (R2=0.53, n=439). The power relation relating the flow width (w) to the discharge (Q) was statistically different on the gentle and the steep sites. A multi regression equation for estimating the width of the concentrated flow as a function of flow discharge, slope, and vegetation cover was developed (R2=0.62, n=360), where the variation of slope alone explained 39% of the

  9. Mass movement hazard assessment model in the slope profile

    Science.gov (United States)

    Colangelo, A. C.

    2003-04-01

    The central aim of this work is to assess the spatial behaviour of critical depths for slope stability and the behaviour of their correlated variables in the soil-regolith transition along slope profiles over granite, migmatite and mica-schist parent materials in an humid tropical environment. In this way, we had making measures of shear strength for residual soils and regolith materials with soil "Cohron Sheargraph" apparatus and evaluated the shear stress tension behaviour at soil-regolith boundary along slope profiles, in each referred lithology. In the limit equilibrium approach applied here we adapt the infinite slope model for slope analysis in whole slope profile by means of finite element solution like in Fellenius or Bishop methods. In our case, we assume that the potential rupture surface occurs at soil-regolith or soil-rock boundary in slope material. For each slice, the factor of safety was calculated considering the value of shear strength (cohesion and friction) of material, soil-regolith boundary depth, soil moisture level content, slope gradient, top of subsurface flow gradient, apparent soil bulk density. The correlations showed the relative weight of cohesion, internal friction angle, apparent bulk density of soil materials and slope gradient variables with respect to the evaluation of critical depth behaviour for different simulated soil moisture content levels at slope profile scale. Some important results refer to the central role of behaviour of soil bulk-density variable along slope profile during soil evolution and in present day, because the intense clay production, mainly Kaolinite and Gibbsite at B and C-horizons, in the humid tropical environment. A increase in soil clay content produce a fall of friction angle and bulk density of material, specially when some montmorillonite or illite clay are present. We have observed too at threshold conditions, that a slight change in soil bulk-density value may disturb drastically the equilibrium of

  10. Effect of cement injection on sandy soil slope stability, case study: slope in Petang district, Badung regency

    Science.gov (United States)

    Arya, I. W.; Wiraga, I. W.; GAG Suryanegara, I.

    2018-01-01

    Slope is a part of soil topography formed due to elevation difference from two soil surface. Landslides is frequently occur in natural slope, it is because shear force is greater than shear strength in the soil. There are some factor that influence slope stability such as: rain dissipation, vibration from earthquake, construction and crack in the soil. Slope instability can cause risk in human activity or even threaten human lives. Every years in rainy season, landslides always occur in Indonesia. In 2016, there was some landslide occurred in Bali. One of the most damaging is landslide in Petang district, Badung regency. This landslide caused main road closed entirely. In order to overcome and prevent landslide, a lot of method have been practiced and still looking for more sophisticated method for forecasting slope stability. One of the method to strengthen soil stability is filling the soil pores with some certain material. Cement is one of the material that can be used to fill the soil pores because when it is in liquid form, it can infiltrate into soil pores and fill the gap between soil particles. And after it dry, it can formed a bond with soil particle so that soil become stronger and the slope as well. In this study, it will use experimental method, slope model in laboratory to simulate a real slope behavior in the field. The first model is the slope without any addition of cement. This model will be become a benchmark for the other models. The second model is a slope with improved soil that injects the slope with cement. Injection of cement is done with varying interval distance of injection point is 5 cm and 10 cm. Each slope model will be given a load until the slope collapses. The slope model will also be analyzed with slope stability program. The test results on the improved slope models will be compared with unimproved slope. In the initial test will consist of 3 model. First model is soil without improvement or cement injection, second model is soil

  11. NRL Glider Data Report for the Shelf-Slope Experiment

    Science.gov (United States)

    2017-09-12

    Transformation and Transport in the Northern Gulf of Mexico: Platform Proof of Concept for the Ocean Observing System in the Northern Gulf of Mexico...glider SL083 was deployed for the Shelf-Slope experiment: “Shelf-Slope Interactions and Carbon Transformation and Transport in the Northern Gulf of... Digital Environmental Model (GDEM) climatology profiles. Optics QC generates flags to indicate that manual examination of profiles is required. Both

  12. Digital analysis of the slopes of Rab Island

    OpenAIRE

    Mladen Pahernik

    2007-01-01

    The paper analyzes morphometric features of the slopes of Rab Island. Based on the digital elevation model, raster layers were calculated for the values of slope angle, aspect and curvature, as well as valley network, which was grouped using the Strahler method. A comparative analysis of the calculated values of morphometric parameters was conducted in the GIS environment. Spatial distribution of the values of each of the morphometric parameters was correlated to the structural and morphogene...

  13. Modelling the influence of tree removal on embankment slope hydrology

    OpenAIRE

    Briggs, Kevin; Smethurst, Joel; Powrie, William

    2014-01-01

    Trees cover the slopes of many railway earthworks supporting the UK’s transport network. Root water uptake by trees can cause seasonal shrinkage and swelling of the embankment soil, affecting the line and level of the railway track. This requires continual maintenance to maintain the serviceability of the track and reduce train speed restrictions. However, the removal of trees from railway embankment slopes and the loss of soil suctions generated by root water uptake may negatively impact emb...

  14. Effects of surface slope on erosion rates of quartz particles

    OpenAIRE

    Lodge, Phillip.

    2006-01-01

    Modeling sediment erosion is important in a wide range of environmental problems. The effects of various environmental factors on erosion rates have been studied, but the effects of surface slope on erosion rates of a wide range of sediments have not been quantified. The effects of surface slope, both in the direction of flow (pitch) and perpendicular to the flow (roll), on erosion rates of quartz particles were investigated using the Sediment Erosion at Depth Flume (Sedflume). US Navy (US...

  15. Spatial position influences perception of slope from graphs.

    Science.gov (United States)

    Parrott, Stacey; Guzman-Martinez, Emmanuel; Ortega, Laura; Grabowecky, Marcia; Huntington, Mark D; Suzuki, Satoru

    2014-01-01

    We routinely examine linear trends from bar graphs and scatterplots while taking a science class, attending a business presentation, or reading a magazine article. Graphs are placed in different positions on a page or a presentation slide for aesthetic considerations. However, because left and right positions tend to be associated with lower and higher values in the conventional depiction of numerical values, we hypothesized that the perception of positive and negative slopes may be influenced by the placement of a graph. Using a visual search task, with each display containing four bar graphs or scatterplots (one per quadrant), we have demonstrated that the detection of a negative slope is selectively slowed in the upper-right quadrant (for both bar graphs and scatterplots), whereas the detection of a positive slope is selectively slowed in the upper-left quadrant (for bar graphs only). These results suggest that an upper-right position is incompatible with perceiving negative slopes and an upper-left position is incompatible with perceiving positive slopes. Although the origin of these specific associations is unclear, our results have implications for where to place a graph depending on the slope it displays.

  16. Sound velocity profiles from underway sound velocimeter casts from NOAA Ship FAIRWEATHER in coastal Alaskan waters from 2006-05-02 to 2006-10-28 (NODC Accession 0013954)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sound velocity profiles were collected from underway sound velocimeter casts from NOAA Ship FAIRWEATHER in coastal Alaskan waters. The National Ocean Service (NOS)...

  17. Putative adaptive inter-slope divergence of transposon frequency in fruit flies (Drosophila melanogaster) at "Evolution Canyon", Mount Carmel, Israel.

    Science.gov (United States)

    Beiles, Avigdor; Raz, Shmuel; Ben-Abu, Yuval; Nevo, Eviatar

    2015-10-14

    The current analysis of transposon elements (TE) in Drosophila melanogaster at Evolution Canyon, (EC), Israel, is based on data and analysis done by our collaborators (Drs. J. Gonzalez, J. Martinez and W. Makalowski, this issue). They estimated the frequencies of 28 TEs (transposon elements) in fruit flies (D. melanogaster) from the ecologically tropic, hot, and dry south-facing slope (SFS) or "African" slope (AS) of EC and compared it with the TE frequencies on the temperate-cool and humid north-facing slope (NFS) or "European" slope (ES), separated, on average, by 250 m. The flies were sampled from two stations on each slope. We received their results, including the frequencies of each TE on each slope, and the probabilities of the statistical analyses (G-tests) of each TE separately. We continued the analysis of the inter-slope differences of the frequencies of the TEs, and based our different conclusions on that analysis and on the difference between micro (=EC) and macro (2000 km.) comparisons [Gonzalez et al. 2015 doi: 10.1186/s13062-015-0075-4 ]. Our collaborators based all their conclusions on the non-significant results of each of the individual tests of the 28 TEs. We analysed also the distribution of the TE differences between the slopes, based on their results. Thirteen TEs were more frequent on the SFS, 11 were more frequent on the NFS, and four had equal frequencies. Because of the equalizing effect of the ongoing migration, only small and temporary differences between the slopes (0 - 0.06) were regarded by us as random fluctuations (drift). Three TEs were intermediate (0.08-0.09) and await additional research. The 11 TEs with large frequency differences (0.12 - 0.22) were regarded by us as putative adaptive TEs, because the equalizing power of ongoing migration will eliminate random large differences. Five of them were higher on the SFS and six were higher on the NFS. Gaps in the distribution of the differences distinguished between the large and

  18. Soil properties in high-elevation ski slopes

    Science.gov (United States)

    Filippa, Gianluca; Freppaz, Michele; Letey, Stéphanie; Corti, Giuseppe; Cocco, Stefania; Zanini, Ermanno

    2010-05-01

    The development of winter sports determines an increasing impact on the high altitude ecosystems, as a consequence of increased participation and an increasing demand of high quality standards for skiable areas. The construction of a ski slope is associated with a certain impact on soil, which varies as a function of the degree of human-induced disturbance to the native substrata. In this work, we provide a description of the characteristics of alpine tundra ski-slope soils and their nutrient status, contrasted with undisturbed areas. The study site is located in the Monterosaski Resort, Aosta Valley, NW Italy (45°51' N; 7°48' E). We chose 5 sites along an altitudinal gradient between 2700 and 2200 m a.s.l.. Per each site, one plot was established on the ski slope, while a control plot was chosen under comparable topographic conditions a few meters apart. Soils were described and samples were collected and analysed for main chemical-physical properties. In addition an evaluation of N forms, organic matter fractionation and microbial biomass was carried out. Soil depth ranged between 10 to more than 70 cm, both on the ski slope and in the undisturbed areas. A true organo-mineral (A) horizon was firstly identified at 2500 m a.s.l., while a weathering horizon (Bw) was detected at 2400 m a.s.l.. However, a Bw horizon thick enough to be recognised as diagnostic for shifting soil classification order from Entisols to Inceptisols (USDA-Soil Taxonomy) was detected only below 2400 m a.s.l.. Lithic Cryorthents were predominant in the upper part of the sequence (above 2500 m a.s.l.), both in the ski slope and the undisturbed areas; Typic Cryorthents were identified between 2500 and 2400 m a.s.l., while Inceptisols were predominant between 2400 and 2200 m a.s.l.. Chemical-physical properties will be discussed focusing on the main differences between ski slope and undisturbed soils, as determined by the ski slope construction. Pedogenetic processes at high altitude are

  19. Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope was calculated from the bathymetry surface for each raster cell using ArcGIS's Spatial Analyst 'Slope' Tool. Slope describes the maximum steepness of a terrain...

  20. Effects of slope smoothing in river channel modeling

    Science.gov (United States)

    Kim, Kyungmin; Liu, Frank; Hodges, Ben R.

    2017-04-01

    In extending dynamic river modeling with the 1D Saint-Venant equations from a single reach to a large watershed there are critical questions as to how much bathymetric knowledge is necessary and how it should be represented parsimoniously. The ideal model will include the detail necessary to provide realism, but not include extraneous detail that should not exert a control on a 1D (cross-section averaged) solution. In a Saint-Venant model, the overall complexity of the river channel morphometry is typically abstracted into metrics for the channel slope, cross-sectional area, hydraulic radius, and roughness. In stream segments where cross-section surveys are closely spaced, it is not uncommon to have sharp changes in slope or even negative values (where a positive slope is the downstream direction). However, solving river flow with the Saint-Venant equations requires a degree of smoothness in the equation parameters or the equation set with the directly measured channel slopes may not be Lipschitz continuous. The results of non-smoothness are typically extended computational time to converge solutions (or complete failure to converge) and/or numerical instabilities under transient conditions. We have investigated using cubic splines to smooth the bottom slope and ensure always positive reference slopes within a 1D model. This method has been implemented in the Simulation Program for River Networks (SPRNT) and is compared to the standard HEC-RAS river solver. It is shown that the reformulation of the reference slope is both in keeping with the underlying derivation of the Saint-Venant equations and provides practical numerical stability without altering the realism of the simulation. This research was supported in part by the National Science Foundation under grant number CCF-1331610.

  1. Integration of two-phase solid fluid equations in a catchment model for flashfloods, debris flows and shallow slope failures

    KAUST Repository

    Bout, B.

    2018-04-09

    An integrated, modeling method for shallow landslides, debris flows and catchment hydrology is developed and presented in this paper. Existing two-phase debris flow equations and an adaptation on the infinite slope method are coupled with a full hydrological catchment model. We test the approach on the 4 km2 Scaletta catchment, North-Eastern Sicily, where the 1-10-2009 convective storm caused debris flooding after 395 shallow landslides. Validation is done based on the landslide inventory and photographic evidence from the days after the event. Results show that the model can recreate the impact of both shallow landslides, debris flow runout, and debris floods with acceptable accuracy (91 percent inventory overlap with a 0.22 Cohens Kappa). General patterns in slope failure and runout are well-predicted, leading to a fully physically based prediction of rainfall induced debris flood behavior in the downstream areas, such as the creation of a debris fan at the coastal outlet.

  2. A newly described group of thermal springs and solfatar fields on the western slope of Dokuchaev's ridge, Kunashir Island

    Directory of Open Access Journals (Sweden)

    Yuri N. Sundukov

    2017-08-01

    Full Text Available As a result of field research in a remote and poorly studied area in the north-west of Kunashir Island, an unknown group of hydrothermal-solfataric post-volcanic activity was discovered on the western slope of the volcano Ruruy, named by the authors – Dal'nie springs. In total eight objects were examined: 1 two small solfataric fields, 2 a small lake and a small stream with «acid springs» and gas outlets, 3 two small glades with mofettes among the bamboo, on which a warm or fairly hot steam flows from small holes in the ground, 4 and two mountain lakes – Lake Vodopadnoe and Lake Khmuroe. Perhaps, the cup-like hollow in which the discovered objects are located is an ancient explosive crater formed on the western slope of volcano Ruruy as a result of a strong eruption.

  3. Communicating Risk and Cultivating Resilience in Rural Alaskan Communities: A Multi-Disciplinary Approach to Flood Mitigation

    Science.gov (United States)

    Kontar, Y. Y.

    2014-12-01

    The increasing extent and vulnerability of technologically advanced society together with aspects of global climate change intensifies the frequency and severity of natural disasters. Every year, communities around the world face the devastating consequences of hazardous events, including loss of life, property and infrastructure damage, and environmental decline. Environmentally sound strategies have to be developed to minimize these consequences. However, hazard-prone areas differ geographically, climatically, and culturally. There is no a one-size-fits-all solution. Thus, it is crucial that future decision-makers not only know the conditions that make some natural Earth processes hazardous to people, but also understand how people perceive and adjust to potential natural hazards in their regions. In May 2013, an ice jam caused major flooding in Galena, a remote village in interior Alaska. Within two days, flooding destroyed nearly the entire region's infrastructure, and displaced over 400 residents. Almost a year later, a significant part of Galena's population was still evacuated in Fairbanks and other neighboring towns. The rebuilding holdup reflected the federal government's reluctance to spend millions of dollars an the area that may be destroyed again by the next flood. Massive floods inundated towns along the Yukon River before (e.g., Eagle in 2009 and Holycross in 1975), but people return to refurbish and again inhabit the same territories. Rivers have a significant importance to Alaskan rural communities. Not only do rivers provide food, drink, transportation, and in some cases arable land and irrigation, but they also carry cultural significance for the Native Alaskan people. The Galena case study provides a revealing example of challenges of communicating with and educating the public and policy makers about natural hazards.

  4. Direct Strain and Slope and Slope Measurement Using 2D DSPSI

    International Nuclear Information System (INIS)

    Dandach, W.; Molimard, J.; Picart, P.

    2011-01-01

    Large variety of optical full-field measurement techniques are being developed and applied to solve mechanical problems. Since each technique possesses its own merits, it is important to know the capabilities and limitations of such techniques. Among these optical full-field methods, interferometry techniques take an important place. They are based on illumination with coherent light (laser). In shearing interferometry the difference of the out of-plane displacement in two neighboring object points is directly measured. Since object displacement does not result in interferometry fringes, the method is suited for localization of strain concentrations and is indeed used in industry for this purpose. DSPSI possesses the advantage over conventional out-of-plane displacement-sensitive interferometry, that only a single difference of the unwrapped phase map is required to obtain flexural strains, thereby relieving problems with noise and reduction in the field of view. A first work in this domain (DSPSI) [1] was made in 1973, later recent studies emerged to provide a quantitative system of measurements [2]. This work aims to present the results of strain and slope measurements using digital speckle pattern shearing interferometry (DSPSI). (author)

  5. Microbial community response to permafrost thaw after wildfire in an Alaskan upland boreal forest

    Science.gov (United States)

    Tas, N.; Jorgenson, M. T.; Wang, S.; Berhe, A. A.; Wickland, K. P.; Waldrop, M. P.; Jansson, J. K.

    2012-12-01

    Fire is a major factor controlling the long-term dynamics of soil carbon in Alaskan boreal forests. Wildfire not only contributes to a significant global emission of greenhouse gasses but also can indirectly result in the deepening of the active layer and thawing of near-surface permafrost due to reductions in organic layer depth and increases in heat flux through soil. Although boreal ecosystems are fire-adapted, increased fire frequency and rising global temperatures may result in warmer soils and therefore increase the metabolic rates of decomposer microbes and result in accelerated permafrost decomposition and greenhouse gas fluxes. In addition to fire-mediated changes in soil and vegetation structure, changes in the soil microbial community structure are likely to have consequences for rates of soil carbon cycling. In this study we aimed to define the impact of fire on soil microbial communities in an upland black spruce forest and to assess microbial metabolic potential for soil respiration, methanogenesis, and nitrous oxide (N2O) flux. Soil samples from two fire impacted and three control (unburned) locations were collected near Nome Creek, AK, an upland moderately drained black spruce forest. This location was within the Boundary fire that burned between mid-June and the end of August 2004. Soil temperature measurements from before and after the fire showed that soils were warmer after the fire event and the permafrost thawed below 1m. At each sampling location, soil and permafrost samples were collected every 10 cm to a depth of 1 m. Besides biochemical characterization, CO2, CH4, N2O fluxes and potential activities of enzymes involved in extracellular decomposition of complex organic molecules (hemicellulose, chitin and lignin) were measured. The microbial community composition in the samples was determined by sequencing of 16S rRNA genes and microbial metabolic potential was assessed via sequencing of total genomic DNA (metagenomics) in selected active

  6. Slope Instability Risk Analysys of the Municipality of Comala, Colima , Mexico

    Science.gov (United States)

    Ramirez-Ruiz, J. J.

    2017-12-01

    Every year during the rainy season occur the problem of mass landslide in some areas of the community of Comala, Colima Mexico. Slope instability is studied in this volcanic region which is located in the southern part of the Volcan de Fuego de Colima. It occurs due to the combination of different factors existing in this area as: Precipitation, topography contrast, type and mechanical properties of deposits that constitute the rocks and soils of the region and the erosion due to the elimination of vegetation deck to develop and grow urban areas. To these geological factors we can extend the tectonic activity of the Western part of Mexico that originate high seismicity by the interaction of Cocos plate and North America plate forming the region of Graben de Colima, were is located this area. Here we will present a Zonification and determination of Slope Instability Risk Maps due to the rain and seismicity accelerators factors. This Study is parto of a proyect to reduce the risk of this phenomenon, it was carried out as part of the National Risk Map of Mexico analized using the CENAPRED methodology to zonificate the risk areas. The instability of slopes is determined both in its origin and in its development, by different mechanisms. In such a way that this process of instability can be grouped into four main categories: Falls or landslides, Flows, Slips and expansions or lateral landslides. Here it is presented the Risk analisis to this volcanic area that cover the municipality of Comala in the State of Colima, Mexico using the Susceptibility map, Risk Map and Risk analisis of the Municipality.

  7. Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands

    Science.gov (United States)

    Merritt R. Turetsky; Evan S. Kane; Jennifer W. Harden; Roger D. Ottmar; Kristen L. Maines; Elizabeth Hoy; Eric S. Kasischke

    2010-01-01

    Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult...

  8. Paired serologic and polymerase chain reaction analyses of avian influenza prevalence in Alaskan shorebirds

    Science.gov (United States)

    Pearce, John M.; Ruthrauff, Daniel R.; Hall, Jeffrey S.

    2012-01-01

    Surveillance has revealed low prevalence of avian influenza viruses (AIV) in shorebirds except Ruddy Turnstones (Arenaria interpres) on the North American Atlantic coast. Similarly, of five species of shorebirds surveyed in Alaska in 2010, Ruddy Turnstones had the highest AIV antibody prevalence; prevalence of AIV RNA was low or zero.

  9. Modeling impacts of fire severity on successional trajectories and future fire behavior in Alaskan boreal forests

    Science.gov (United States)

    Jill F. Johnstone; T. Scott Rupp; Mark Olson; David. Verbyla

    2011-01-01

    Much of the boreal forest in western North America and Alaska experiences frequent, stand-replacing wildfires. Secondary succession after fire initiates most forest stands and variations in fire characteristics can have strong effects on pathways of succession. Variations in surface fire severity that influence whether regenerating forests are dominated by coniferous...

  10. Analysis of bubble plume distributions to evaluate methane hydrate decomposition on the continental slope

    Science.gov (United States)

    Johnson, H. Paul; Miller, Una K.; Salmi, Marie S.; Solomon, Evan A.

    2015-11-01

    Cascadia margin sediments contain a rich reservoir of carbon derived both from terrestrial input and sea surface productivity. A portion of this carbon exists as solid gas hydrate within sediment pore spaces which previous studies have shown to be a methane reservoir of substantial size on both the Vancouver Island and Oregon portions of the Cascadia margin. Multichannel seismic reflection profiles on the Cascadia margin show the widespread presence of Bottom Simulating Reflectors (BSRs) within the sediment column, indicating the gas hydrate reservoir extends from the deformation front at 3000 m depth to the upper limit of gas hydrate stability near 500 m water depth. In this study, we compile an inventory of methane bubble plume sites on the Cascadia margin identified in investigations carried out for a range of interdisciplinary goals that also include sites volunteered by commercial fishermen. High plume density anomalies are associated with both the continental shelf (<180 m) and the depth of the upper limit of methane hydrate stability depth (MHSD) that occurs near 500 m in the NE Pacific. The observed anomalies on the Cascadia slope may be due to the warming of seawater at intermediate depths, suggesting that modern climate change has begun to destabilize the climate-sensitive hydrate reservoir within the Cascadia margin sediments. Reanalysis of similar plume images on the North American Atlantic slope suggests a lack of correlation between observed plume depths and the MHSD for much of the latitudinal range.

  11. Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stynes, J. K.; Ihas, B.

    2012-04-01

    The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

  12. Physical Analysis Work for Slope Stability at Shah Alam, Selangor

    Science.gov (United States)

    Ishak, M. F.; Zaini, M. S. I.

    2018-04-01

    Slope stability analysis is performed to assess the equilibrium conditions and the safe design of a human-made or natural slope to find the endangered areas. Investigation of potential failure and determination of the slope sensitivity with regard to safety, reliability and economics were parts of this study. Ground anchor is designed to support a structure in this study. Ground anchor were implemented at the Mechanically Stabilized Earth (MSE) wall along Anak Persiaran Jubli Perak to overcome the further cracking of pavement parking, concrete deck and building of the Apartments. A result from the laboratory testing of soil sample such as index test and shear strength test were applied to the Slope/W software with regard to the ground anchors that were implemented. The ground anchors were implemented to increase the value of the factor of safety (FOS) of the MSE Wall. The value of the factor of safety (FOS) before implementing the ground anchor was 0.800 and after the ground anchor was implemented the value increase to 1.555. The increase percentage of factor of safety by implementing on stability of slope was 94.38%.

  13. Landform Degradation and Slope Processes on Io: The Galileo View

    Science.gov (United States)

    Moore, Jeffrey M.; Sullivan, Robert J.; Chuang, Frank C.; Head, James W., III; McEwen, Alfred S.; Milazzo, Moses P.; Nixon, Brian E.; Pappalardo, Robert T.; Schenk, Paul M.; Turtle, Elizabeth P.; hide

    2001-01-01

    The Galileo mission has revealed remarkable evidence of mass movement and landform degradation on Io. We recognize four major slope types observed on a number of intermediate resolution (250 m/pixel) images and several additional textures on very high resolution (10 m/pixel) images. Slopes and scarps on Io often show evidence of erosion, seen in the simplest form as alcove-carving slumps and slides at all scales. Many of the mass movement deposits on Io are probably mostly the consequence of block release and brittle slope failure. Sputtering plays no significant role. Sapping as envisioned by McCauley et al. remains viable. We speculate that alcove-lined canyons seen in one observation and lobed deposits seen along the bases of scarps in several locations may reflect the plastic deformation and 'glacial' flow of interstitial volatiles (e.g., SO2) heated by locally high geothermal energy to mobilize the volatile. The appearance of some slopes and near-slope surface textures seen in very high resolution images is consistent with erosion from sublimation-degradation. However, a suitable volatile (e.g., H2S) that can sublimate fast enough to alter Io's youthful surface has not been identified. Disaggregation from chemical decomposition of solid S2O and other polysulfur oxides may conceivably operate on Io. This mechanism could degrade landforms in a manner that resembles degradation from sublimation, and at a rate that can compete with resurfacing.

  14. Surface drainage in leveled land: Implication of slope

    Directory of Open Access Journals (Sweden)

    Antoniony S. Winkler

    Full Text Available ABSTRACT In the lowlands of Rio Grande do Sul, land leveling is mostly carried out with no slope for the purpose of rice production. In this environment, soils with a low hydraulic conductivity are predominant owing to the presence of a practically impermeable B-horizon near the surface. Land leveling leads to soil accommodation resulting in the formation of depressions where water accumulates after heavy rainfalls, subsequently leading to problems with crops implanted in succession to rice, such as soybeans. The objective of this research was to quantify the areas and volumes of water accumulation in soil as a function of the slope of land leveling. Five typical leveled lowland areas were studied as a part of this research. The original areas presented slopes of 0, 0.20, 0.25, 0.28 and 0.40%, which were used to generate new digital elevation models with slopes between 0 and 0.5%. These newly generated digital models were used to map the depressions with surface water storage. In conclusion, land leveling with slopes higher than 0.1% is recommended to minimize problems with superficial water storage in rice fields.

  15. Characterization of Unstable Rock Slopes Through Passive Seismic Measurements

    Science.gov (United States)

    Kleinbrod, U.; Burjanek, J.; Fäh, D.

    2014-12-01

    Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. An analysis of ambient vibrations of unstable rock slopes might be a new alternative to the already existing methods, e.g. geotechnical displacement measurements. Systematic measurements have been performed recently in Switzerland to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. Each measurement setup included a reference station, which was installed on a stable part close to the instability. Recorded ground motion is highly directional in the unstable parts of the rock slope, and significantly amplified with respect to stable areas. These effects are strongest at certain frequencies, which were identified as eigenfrequencies of the unstable rock mass. In most cases the directions of maximum amplification are perpendicular to open cracks and in good agreement with the deformation directions obtained by geodetic measurements. Such unique signatures might improve our understanding of slope structure and stability. Thus we link observed vibration characteristics with available results of detailed geological characterization. This is supported by numerical modeling of seismic wave propagation in fractured media with complex topography.For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

  16. Control and perception of balance at elevated and sloped surfaces.

    Science.gov (United States)

    Simeonov, Peter I; Hsiao, Hongwei; Dotson, Brian W; Ammons, Douglas E

    2003-01-01

    Understanding roof-work-related risk of falls and developing low-cost, practical engineering controls for reducing this risk remain in high demand in the construction industry. This study investigated the effects of the roof work environment characteristics of surface slope, height, and visual reference on standing balance in construction workers. The 24 participants were tested in a laboratory setting at 4 slopes (0 degrees, 18 degrees, 26 degrees, and 34 degrees), 2 heights (0, 3 m), and 2 visual conditions (with and without visual references). Postural sway characteristics were calculated using center of pressure recordings from a force platform. Workers' perceptions of postural sway and instability were also evaluated. The results indicated that slope and height synergistically increased workers' standing postural instability. Workers recognized the individual destabilizing effects of slope and height but did not recognize the synergistic effect of the two. Visual references significantly reduced the destabilizing effects of height and slope. Actual and potential applications of this research include the use of temporary level work surfaces and proximal vertical reference structures as postural instability control measures during roofing work.

  17. The Influence of Slope Breaks on Lava Flow Surface Disruption

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Stephen M.; Fagents, Sarah A.; Wright, Robert

    2014-01-01

    Changes in the underlying slope of a lava flow impart a significant fraction of rotational energy beyond the slope break. The eddies, circulation and vortices caused by this rotational energy can disrupt the flow surface, having a significant impact on heat loss and thus the distance the flow can travel. A basic mechanics model is used to compute the rotational energy caused by a slope change. The gain in rotational energy is deposited into an eddy of radius R whose energy is dissipated as it travels downstream. A model of eddy friction with the ambient lava is used to compute the time-rate of energy dissipation. The key parameter of the dissipation rate is shown to be rho R(sup 2/)mu, where ? is the lava density and mu is the viscosity, which can vary by orders of magnitude for different flows. The potential spatial disruption of the lava flow surface is investigated by introducing steady-state models for the main flow beyond the steepening slope break. One model applies to slow-moving flows with both gravity and pressure as the driving forces. The other model applies to fast-moving, low-viscosity, turbulent flows. These models provide the flow velocity that establishes the downstream transport distance of disrupting eddies before they dissipate. The potential influence of slope breaks is discussed in connection with field studies of lava flows from the 1801 Hualalai and 1823 Keaiwa Kilauea, Hawaii, and 2004 Etna eruptions.

  18. Hyperstereopsis in helmet-mounted NVDs: slope perception

    Science.gov (United States)

    Stuart, Geoffrey W.; Flanagan, Patrick; Gibbs, Peter

    2007-04-01

    Modern helmet-mounted night vision devices, such as the Thales TopOwl helmet, project imagery from intensifiers mounted on the sides of the helmet onto the helmet faceplate. This produces a situation of hyperstereopsis in which binocular disparities are magnified. This has the potential to distort the perception of slope in depth (an important cue to landing), because the slope cue provided by binocular disparity conflicts with veridical cues to slope, such as texture gradients and motion parallax. In the experiments, eight observers viewed sparse and dense textured surfaces tilted in depth under three viewing conditions: normal stereo hyper-stereo (4 times magnification), and hypostereo (1/4 magnification). The surfaces were either stationary, or rotated slowly around a central vertical axis. Stimuli were projected at 6 metres to minimise conflict between accommodation and convergence, and stereo viewing was provided by a Z-screen and passive polarised glasses. Observers matched perceived visual slope using a small tilt table set by hand. We found that slope estimates were distorted by hyperstereopsis, but to a much lesser degree than predicted by disparity magnification. The distortion was almost completely eliminated when motion parallax was present.

  19. Deep currents in the Gulf of Guinea: along slope propagation of intraseasonal waves

    Directory of Open Access Journals (Sweden)

    C. Guiavarc'h

    2009-05-01

    Full Text Available In the Gulf of Guinea, intraseasonal variability is large at the equator and along the coast. Current data on the continental slope near 7.5° S show very energetic biweekly oscillations at 1300 m depth. A high resolution primitive equation numerical model demonstrates that this deep variability is forced by equatorial winds, through the generation of equatorial Yanai waves that propagate eastward and at depth, and then poleward as coastally-trapped waves upon reaching the coast of Africa. Intraseasonal variability is intensified along the coast of the Gulf of Guinea, especially in the 10–20 day period range and at depths between 500 and 1500 m. The kinetic energy distribution is well explained at first order by linear theory. Along the equator, eastward intensification of energy and bottom intensification are in qualitative agreement with vertically propagating Yanai waves, although the signal is influenced by the details of the bathymetry. Along the coast, baroclinic modes 3 to 5 are important close to the equator, and the signal is dominated by lower vertical modes farther south. Additional current meter data on the continental slope near 3° N display an energy profile in the 10–20 day period band that is strikingly different from the one at 7.5° S, with surface intensification rather than bottom intensification and a secondary maximum near 800 m. The model reproduces these features and explains them: the surface intensification in the north is due to the regional wind forcing, and the north-south asymmetry of the deep signal is due to the presence of the zonal African coast near 5° N. A 4 years time series of current measurements at 7.5° S shows that the biweekly oscillations are intermittent and vary from year to year. This intermittency is not well correlated with fluctuations of the equatorial winds and does not seem to be a simple linear response to the wind forcing.

  20. Key indicator tools for shallow slope failure assessment using soil chemical property signatures and soil colour variables.

    Science.gov (United States)

    Othman, Rashidi; Hasni, Shah Irani; Baharuddin, Zainul Mukrim; Hashim, Khairusy Syakirin Has-Yun; Mahamod, Lukman Hakim

    2017-10-01

    Slope failure has become a major concern in Malaysia due to the rapid development and urbanisation in the country. It poses severe threats to any highway construction industry, residential areas, natural resources and tourism activities. The extent of damages that resulted from this catastrophe can be lessened if a long-term early warning system to predict landslide prone areas is implemented. Thus, this study aims to characterise the relationship between Oxisols properties and soil colour variables to be manipulated as key indicators to forecast shallow slope failure. The concentration of each soil property in slope soil was evaluated from two different localities that consist of 120 soil samples from stable and unstable slopes located along the North-South Highway (PLUS) and East-West Highway (LPT). Analysis of variance established highly significant difference (P < 0.0001) between the locations, the total organic carbon (TOC), soil pH, cation exchange capacity (CEC), soil texture, soil chromaticity and all combinations of interactions. The overall CIELAB analysis leads to the conclusion that the CIELAB variables lightness L*, c* (Chroma) and h* (Hue) provide the most information about soil colour and other related soil properties. With regard to the relationship between colour variables and soil properties, the analysis detected that soil texture, organic carbon, iron oxide and aluminium concentration were the key factors that strongly correlate with soil colour variables at the studied area. Indicators that could be used to predict shallow slope failure were high value of L*(62), low values of c* (20) and h* (66), low concentration of iron (53 mg kg -1 ) and aluminium oxide (37 mg kg -1 ), low soil TOC (0.5%), low CEC (3.6 cmol/kg), slightly acidic soil pH (4.9), high amount of sand fraction (68%) and low amount of clay fraction (20%).

  1. Probabilistic approaches for geotechnical site characterization and slope stability analysis

    CERN Document Server

    Cao, Zijun; Li, Dianqing

    2017-01-01

    This is the first book to revisit geotechnical site characterization from a probabilistic point of view and provide rational tools to probabilistically characterize geotechnical properties and underground stratigraphy using limited information obtained from a specific site. This book not only provides new probabilistic approaches for geotechnical site characterization and slope stability analysis, but also tackles the difficulties in practical implementation of these approaches. In addition, this book also develops efficient Monte Carlo simulation approaches for slope stability analysis and implements these approaches in a commonly available spreadsheet environment. These approaches and the software package are readily available to geotechnical practitioners and alleviate them from reliability computational algorithms. The readers will find useful information for a non-specialist to determine project-specific statistics of geotechnical properties and to perform probabilistic analysis of slope stability.

  2. Rock mass characterisation and stability analyses of excavated slopes

    Science.gov (United States)

    Zangerl, Christian; Lechner, Heidrun

    2016-04-01

    Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deep-seated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stress-strain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about in-situ stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, large-scale in-situ testing is difficult and costly, back-calculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning back-calculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on

  3. Some Limits Using Random Slope Models to Measure Academic Growth

    Directory of Open Access Journals (Sweden)

    Daniel B. Wright

    2017-11-01

    Full Text Available Academic growth is often estimated using a random slope multilevel model with several years of data. However, if there are few time points, the estimates can be unreliable. While using random slope multilevel models can lower the variance of the estimates, these procedures can produce more highly erroneous estimates—zero and negative correlations with the true underlying growth—than using ordinary least squares estimates calculated for each student or school individually. An example is provided where schools with increasing graduation rates are estimated to have negative growth and vice versa. The estimation is worse when the underlying data are skewed. It is recommended that there are at least six time points for estimating growth if using a random slope model. A combination of methods can be used to avoid some of the aberrant results if it is not possible to have six or more time points.

  4. Mars Climate History: Insights From Impact Crater Wall Slope Statistics

    Science.gov (United States)

    Kreslavsky, Mikhail A.; Head, James W.

    2018-02-01

    We use the global distribution of the steepest slopes on crater walls derived from Mars Orbiter Laser Altimeter profile data to assess the magnitudes of degradational processes with latitude, altitude, and time. We independently confirm that Amazonian polar/high-latitude crater slope modification is substantial, but that craters in the low latitudes have essentially escaped significant slope modification since the Early Hesperian. We find that the total amount of crater wall degradation in the Late Noachian is very small in comparison to the circumpolar regions in the Late Amazonian, an observation that we interpret to mean that the Late Noachian climate was not characterized by persistent and continuous warm and wet conditions. A confirmed elevational zonality in degradation in the Early Hesperian is interpreted to mean that the atmosphere was denser than today.

  5. Development of a new generation of optical slope measuring profiler

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V.; Takacs, Peter Z.; McKinney, Wayne R.; Assoufid, Lahsen; Siewert, Frank; Zeschke, Thomas

    2010-09-16

    A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler -- the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be<50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).

  6. The Socioeconomic Assessment of Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    with the aim to combat deforestation, ecological degradation, over cultivation of sloping land and soil erosion. However, we also believe it brings changes to the rural economic structure and household livelihood strategy. Applying and developing some empirical and theoretical methods with a large amount......Abstract This thesis mainly focuses on the socioeconomic impact of the largest Ecological Recovery Program ― the Sloping Land Conversion Program (SLCP), also called Grain for Green Program (GFG) in China. The central government initiated this program in 1999 and it was launched nationwide in 2002...... that there exist heterogeneous effects of SLCP implementation on livelihood diversification across different rural income groups. The lower income group was more affected by the program in terms of income diversification. The Second paper ― The Effects of Sloping Land Conversion Program on Agricultural Households...

  7. Development of a GIS-based failure investigation system for highway soil slopes

    Science.gov (United States)

    Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.

    2015-06-01

    A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation ( P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

  8. Determination of slope failure using 2-D resistivity method

    Science.gov (United States)

    Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson

    2017-07-01

    Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

  9. Evidence of slope instability in the Southwestern Adriatic Margin

    Directory of Open Access Journals (Sweden)

    D. Minisini

    2006-01-01

    Full Text Available The Southwestern Adriatic Margin (SAM shows evidence of widespread failure events that generated slide scars up to 10 km wide and extensive slide deposits with run out distances greater than 50 km. Chirp-sonar profiles, side-scan sonar mosaics, multibeam bathymetry and sediment cores document that the entire slope area underwent repeated failures along a stretch of 150 km and that mass-transport deposits, covering an area of 3320 km2, are highly variable ranging from blocky slides to turbidites, and lay on the lower slope and in the basin. The SAM slope between 300–700 m is impacted by southward bottom currents shaping sediment drifts (partly affected by failure and areas of dominant erosion of the seafloor. When slide deposits occur in areas swept by bottom currents their fresh appearence and their location at seafloor may give the misleading impression of a very young age. Seismic-stratigraphic correlation of these deposits to the basin floor, however, allow a more reliable age estimate through sediment coring of the post-slide unit. Multiple buried failed masses overlap each other in the lower slope and below the basin floor; the most widespread of these mass-transport deposits occurred during the MIS 2-glacial interval on a combined area of 2670 km2. Displacements affecting Holocene deposits suggest recent failure events during or after the last phases of the last post-glacial eustatic rise. Differences in sediment accumulation rates at the base or within the sediment drifts and presence of downlap surfaces along the slope and further in the basin may provide one or multiple potential weak layers above which widespread collapses take place. Neotectonic activity and seismicity, together with the presence of a steep slope, represent additional elements conducive to sediment instability and failure along the SAM. Evidence of large areas still prone to failure provides elements of tsunamogenic hazard.

  10. Non-electric applications of geothermal energy in six Alaskan towns. Final report, October 1976--November 1977. [Barrow, Huslia, Kiana, Nikolski, Nome, and Wrangell

    Energy Technology Data Exchange (ETDEWEB)

    Farquhar, J.; Grijalva, R.; Kirkwood, P.

    1977-11-01

    The potential for direct (non-electric) utilization of local-gradient geothermal energy in six Alaskan towns is summarized. A major objective of this study was to stimulate development and use of the geothermal resource provided by the earth's average thermal gradient, as opposed to the few anomalies that are typically chosen for geothermal development. Hence, six towns for study were selected as being representative of remote Alaskan conditions, rather than for their proximity to known geothermal resources. The moderate-temperature heat available almost everywhere at depths of two to four kilometers into the earth's mantle could satisfy a major portion of the nation's heating requirements--but the cost must be reduced. It is concluded that a geothermal demonstration in Nome would probably be successful and would promote this objective.

  11. Measurement of the π0 electromagnetic transition form factor slope

    Science.gov (United States)

    Lazzeroni, C.; Lurkin, N.; Romano, A.; Blazek, T.; Koval, M.; Ceccucci, A.; Danielsson, H.; Falaleev, V.; Gatignon, L.; Goy Lopez, S.; Hallgren, B.; Maier, A.; Peters, A.; Piccini, M.; Riedler, P.; Frabetti, P. L.; Gersabeck, E.; Kekelidze, V.; Madigozhin, D.; Misheva, M.; Molokanova, N.; Movchan, S.; Potrebenikov, Yu.; Shkarovskiy, S.; Zinchenko, A.; Rubin, P.; Baldini, W.; Cotta Ramusino, A.; Dalpiaz, P.; Fiorini, M.; Gianoli, A.; Norton, A.; Petrucci, F.; Savrié, M.; Wahl, H.; Bizzeti, A.; Bucci, F.; Iacopini, E.; Lenti, M.; Veltri, M.; Antonelli, A.; Moulson, M.; Raggi, M.; Spadaro, T.; Eppard, K.; Hita-Hochgesand, M.; Kleinknecht, K.; Renk, B.; Wanke, R.; Winhart, A.; Winston, R.; Bolotov, V.; Duk, V.; Gushchin, E.; Ambrosino, F.; Di Filippo, D.; Massarotti, P.; Napolitano, M.; Palladino, V.; Saracino, G.; Anzivino, G.; Imbergamo, E.; Piandani, R.; Sergi, A.; Cenci, P.; Pepe, M.; Costantini, F.; Doble, N.; Giudici, S.; Pierazzini, G.; Sozzi, M.; Venditti, S.; Balev, S.; Collazuol, G.; DiLella, L.; Gallorini, S.; Goudzovski, E.; Lamanna, G.; Mannelli, I.; Ruggiero, G.; Cerri, C.; Fantechi, R.; Kholodenko, S.; Kurshetsov, V.; Obraztsov, V.; Semenov, V.; Yushchenko, O.; D'Agostini, G.; Leonardi, E.; Serra, M.; Valente, P.; Fucci, A.; Salamon, A.; Bloch-Devaux, B.; Peyaud, B.; Engelfried, J.; Coward, D.; Kozhuharov, V.; Litov, L.; Arcidiacono, R.; Bifani, S.; Biino, C.; Dellacasa, G.; Marchetto, F.; Numao, T.; Retière, F.; NA62 Collaboration

    2017-05-01

    The NA62 experiment collected a large sample of charged kaon decays in 2007 with a highly efficient trigger for decays into electrons. A measurement of the π0 electromagnetic transition form factor slope parameter from 1.11 ×106 fully reconstructed K± →π± πD0, πD0 →e+e- γ events is reported. The measured value a = (3.68 ± 0.57) ×10-2 is in good agreement with theoretical expectations and previous measurements, and represents the most precise experimental determination of the slope in the time-like momentum transfer region.

  12. Wave Run-Up on Sloping Coastal Structures

    DEFF Research Database (Denmark)

    Rouck, J. De; Troch, P.; Ronde, J. De

    2001-01-01

    Wave run-up is one of the main physical processes which are taken into account in the design of the crest level of sloping coastal structures. The crest level design of these structures is mainly based on physical scale model results.......Wave run-up is one of the main physical processes which are taken into account in the design of the crest level of sloping coastal structures. The crest level design of these structures is mainly based on physical scale model results....

  13. After the Slippery Slope: Dutch Experiences on Regulating Active Euthanasia

    OpenAIRE

    Boer, Th.A.

    2003-01-01

    “When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward.” If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery-slope argument, however, is by definition limited by its reference to future developments which cannot empirically be sustained. Experience in the Netherlands—where a law regulating active euthanasia was accepted in April 2001—may shed...

  14. Newton slopes for Artin-Schreier-Witt towers

    DEFF Research Database (Denmark)

    Davis, Christopher; Wan, Daqing; Xiao, Liang

    2016-01-01

    We fix a monic polynomial f(x)∈Fq[x] over a finite field and consider the Artin-Schreier-Witt tower defined by f(x); this is a tower of curves ⋯→Cm→Cm−1→⋯→C0=A1, with total Galois group Zp. We study the Newton slopes of zeta functions of this tower of curves. This reduces to the study of the Newton...... a result on the behavior of the slopes of the eigencurve associated to the Artin-Schreier-Witt tower, analogous to the result of Buzzard and Kilford....

  15. First evidence and predictions of Plasmodium transmission in Alaskan bird populations.

    Directory of Open Access Journals (Sweden)

    Claire Loiseau

    Full Text Available The unprecedented rate of change in the Arctic climate is expected to have major impacts on the emergence of infectious diseases and host susceptibility to these diseases. It is predicted that malaria parasites will spread to both higher altitudes and latitudes with global warming. Here we show for the first time that avian Plasmodium transmission occurs in the North American Arctic. Over a latitudinal gradient in Alaska, from 61°N to 67°N, we collected blood samples of resident and migratory bird species. We found both residents and hatch year birds infected with Plasmodium as far north as 64°N, providing clear evidence that malaria transmission occurs in these climates. Based on our empirical data, we make the first projections of the habitat suitability for Plasmodium under a future-warming scenario in Alaska. These findings raise new concerns about the spread of malaria to naïve host populations.

  16. Breed-Specific Ancestry Studies and Genome-Wide Association Analysis Highlight an Association Between the MYH9 Gene and Heat Tolerance in Alaskan Sprint Racing Sled Dogs

    OpenAIRE

    Huson, Heather J.; vonHoldt, Bridgett M.; Rimbault, Maud; Byers, Alexandra M.; Runstadler, Jonathan A.; Parker, Heidi G.; Ostrander, Elaine A.

    2011-01-01

    Alaskan sled dogs are a genetically distinct population shaped by generations of selective interbreeding with purebred dogs to create a group of high performance athletes. As a result of selective breeding strategies, sled dogs present a unique opportunity to employ admixture-mapping techniques to investigate how breed composition and trait selection impact genomic structure. We used admixture mapping to investigate genetic ancestry across the genomes of two classes of sled dogs, sprint and l...

  17. Spatial variability and its main controlling factors of the permafrost soil-moisture on the northern-slope of Bayan Har Mountains in Qinghai-Tibet Plateau

    Science.gov (United States)

    Cao, W.; Sheng, Y.

    2017-12-01

    The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions. It is very critical to protect the alpine ecology and hydrologic cycle in Qinghai-Tibet Plateau. Especially, it becomes one of the key problems to reveal the spatial-temporal variability of soil moisture movement and its main influence factors in earth system science. Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study. The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree (CART) is adopted to identify the main controlling factors influencing the soil moisture movement. And the relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis (CCA). The results show that: 1) the change of the soil moisture on the permafrost slope is divided into 4 stages, including the freezing stability phase, the rapid thawing phase, the thawing stability phase and the fast freezing phase; 2) this greatly enhances the horizontal flow in the freezing period due to the terrain slope and the freezing-thawing process. Vertical migration is the mainly form of the soil moisture movement. It leads to that the soil-moisture content in the up-slope is higher than that in the down-slope. On the contrary, the soil-moisture content in the up-slope is lower than that in the down-slope during the melting period; 3) the main environmental factors which affect the slope-permafrost soil-moisture are elevation, soil texture, soil temperature and vegetation coverage. But there are differences in the impact factors of the soil moisture in different

  18. A RAB3GAP1 SINE Insertion in Alaskan Huskies with Polyneuropathy, Ocular Abnormalities, and Neuronal Vacuolation (POANV Resembling Human Warburg Micro Syndrome 1 (WARBM1

    Directory of Open Access Journals (Sweden)

    Michaela Wiedmer

    2016-02-01

    Full Text Available We observed a hereditary phenotype in Alaskan Huskies that was characterized by polyneuropathy with ocular abnormalities and neuronal vacuolation (POANV. The affected dogs developed a progressive severe ataxia, which led to euthanasia between 8 and 16 months of age. The pedigrees were consistent with a monogenic autosomal recessive inheritance. We localized the causative genetic defect to a 4 Mb interval on chromosome 19 by a combined linkage and homozygosity mapping approach. Whole genome sequencing of one affected dog, an obligate carrier, and an unrelated control revealed a 218-bp SINE insertion into exon 7 of the RAB3GAP1 gene. The SINE insertion was perfectly associated with the disease phenotype in a cohort of 43 Alaskan Huskies, and it was absent from 541 control dogs of diverse other breeds. The SINE insertion induced aberrant splicing and led to a transcript with a greatly altered exon 7. RAB3GAP1 loss-of-function variants in humans cause Warburg Micro Syndrome 1 (WARBM1, which is characterized by additional developmental defects compared to canine POANV, whereas Rab3gap1-deficient mice have a much milder phenotype than either humans or dogs. Thus, the RAB3GAP1 mutant Alaskan Huskies provide an interesting intermediate phenotype that may help to better understand the function of RAB3GAP1 in development. Furthermore, the identification of the presumed causative genetic variant will enable genetic testing to avoid the nonintentional breeding of affected dogs.

  19. BENTHIC SPECIES and Other Data from FIXED STATIONS From North Atlantic Ocean and Others from 19830501 to 19860731 (NODC Accession 8700358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The three files contain trace metal data from North, Central and South Atlantic observed in bottom sediment samples along the East Coast Continental Slope and Rise...

  20. Notes on eel larvae (Anguilla anguilla Linnaeus, 1758) from the central and eastern North Atlantic and on glass eels from the European continental shelf

    NARCIS (Netherlands)

    Utrecht, van W.L.; Holleboom, M.A.

    1985-01-01

    Eel larvae caught in the mid North Atlantic and along the continental slope off the Portuguese coast are studied together with samples of glass eels caught just before entering fresh water along the Dutch and French coasts. During their migration from the mid Atlantic towards the continental slope

  1. Development of the springbok skin - colour pattern, hair slope and ...

    African Journals Online (AJOL)

    S.-Afr. Tydskr. Dierk. 1989,24(1). Development of the springbok skin - colour pattern, hair slope and horn rudiments in Antidorcas marsupialis. G.H. Findlay. Department of Dermatology, Faculty of Medicine, University of Pretoria, Pretoria, 0001 Republic of South Africa·. Received 19 May 1988; accepted 8 September 1988.

  2. Stability analysis of sandy slope considering anisotropy effect in ...

    Indian Academy of Sciences (India)

    This paper aims to investigate the effect of anisotropy of shear strength parameter on the stability of a sandy slope by performing the limit equilibrium analysis. Because of scarcity of mathematical equation for anisotropic friction angle of sand, at first, all results of principal stress rotation tests are processed by artificial neural ...

  3. Experimental research on stability of covering blocks for sloping banks

    International Nuclear Information System (INIS)

    Okuno, Toshihiko

    1988-01-01

    In the case of constructing thermal and nuclear power stations facing open seas, usually the harbors for unloading fuel and others are constructed. In Japan, breakwaters are installed in the places of relatively shallow depth less than 20 m, and in such case, the sloping banks having the covering material of wave-controlling blocks made of concrete are mostly adopted as those are excellent in their function and economical efficiency, and are advantageous in the maintenance and management. Sloping banks are of such type that wave-controlling blocks cover the vertical front face of nonpermeating caissons, and the same type was adopted for breakwaters and others in Onagawa Nuclear Power Station, Tohoku Electric Power Co., Inc. As for the wave-controlling blocks, tetrapods and shake blocks were used. One of the most important problems in the design of sloping banks is how to estimate the stability of wave controlling blocks. In this paper, the results of the examination by hydraulic model experiment on the stability of covering blocks are reported, which are useful as the basic data for the rational and economical design of sloping banks. The experimental setup and a model bank, the generation of experimental waves and their characteristics, the experimental conditions and experimental method, and the results are reported. (Kako, I.)

  4. Wave Run-Up on Sloping Coastal Structures

    DEFF Research Database (Denmark)

    Rouck, J. De; Troch, P.; Ronde, J. De

    Wave run-up is one of the main physical processes which is taken into account in the design of the crest level of sloping coastal structures. Until recently, solely physical model results were used for the crest level design. However, prototype measurements have indicated that scale models...

  5. Nonlinear assessment of time series from rock slope monitoring

    Czech Academy of Sciences Publication Activity Database

    Zvelebil, J.; Paluš, Milan

    2007-01-01

    Roč. 9 (2007), A-05649 ISSN 1029-7006. [General Asembly of the European Geophysical Society. 15.04.2007-20.04.2007, Vienna] Institutional research plan: CEZ:AV0Z10300504 Keywords : fractal * scaling * unstable rock slope * collapse prediction * engineering geology Subject RIV: DG - Athmosphere Sciences, Meteorology

  6. the Modeling of Hydraulic Jump Generated Partially on Sloping Apron

    Directory of Open Access Journals (Sweden)

    Shaker Abdulatif Jalil

    2017-12-01

    Full Text Available Modeling aims to characterize system behavior and achieve simulation close as possible of the reality. The rapid energy exchange in supercritical flow to generate quiet or subcritical flow in hydraulic jump phenomenon is important in design of hydraulic structures. Experimental and numerical modeling is done on type B hydraulic jump which starts first on sloping bed and its end on horizontal bed.  Four different apron slopes are used, for each one of these slopes the jump is generated on different locations by controlling the tail water depth.  Modelling validation is based on 120 experimental runs which they show that there is reliability. The air volume fraction which creates in through hydraulic jump varied between 0.18 and 0.28. While the energy exchanges process take place within 6.6, 6.1, 5.8, 5.5 of the average relative jump height for apron slopes of 0.18, 0.14, 0.10, 0.07 respectively. Within the limitations of this study, mathematical prediction model for relative hydraulic jump height is suggested.The model having an acceptable coefficient of determination.

  7. Soil erosion and management activities on forested slopes

    Science.gov (United States)

    Robert R. Ziemer

    1986-01-01

    Some of the most productive forests in the Western United States grow on marginally stable mountainous slopes, where disturbance increases the likelihood of erosion. Much of the public's concern about, and, consequently, most of the research on, erosion from these forested areas is related more to the degradation of stream resources by eroded material than to the...

  8. Erosion protection for soil slopes along Virginia's highways.

    Science.gov (United States)

    2000-01-01

    A survey of the state of practice for designing slope erosion control measures within VDOT's nine districts has been conducted. On the basis of the survey, it is clear that there are no specific design procedures currently in use within VDOT for deal...

  9. Effect of Angle of Attack on Slope Climbing Performance

    Science.gov (United States)

    Creager, Colin M.; Jones, Lucas; Smith, Lauren M.

    2017-01-01

    Ascending steep slopes is often a very difficult challenge for off-road vehicles, whether on Earth or on extraterrestrial bodies. This challenge is even greater if the surface consists of loose granular soil that does not provide much shear strength. This study investigated how the path at which a vehicle traverses a slope, specifically the angle that it is commanded to drive relative to the base of the hill (the angle of attack), can affect its performance. A vehicle was driven in loose sand at slope angles up to 15 degrees and angles of attack ranging from 10 to 90 degrees. A novel photogrammetry technique was implemented to both track vehicle motion and create a three-dimensional profile of the terrain. This allowed for true wheel sinkage measurements. The study showed that though low angles of attack result in lower wheel slip and sinkage, the efficiency of the vehicles uphill motion increased at higher angles of attack. For slopes up to 15 degrees, a 90 degree angle of attack provided the greatest likelihood of successful ascent.

  10. End depth in steeply sloping rough rectangular channels

    Indian Academy of Sciences (India)

    Conte S D, de Boor C 1987 Elementary numerical analysis: An algorithmic approach (New York: McGraw-Hill). Davis A C, Ellett B G S, Jacob R P 1998 Flow measurement in sloping channels with rectangular free overfall. J. Hydraul. Eng., Am. Soc. Civ. Eng. 124: 760±763. Davis A C, Jacob R P, Ellett B G S 1999 Estimating ...

  11. Title Qualitative stability assessment of cut slopes along the national ...

    Indian Academy of Sciences (India)

    64

    Monitoring: ISRM Suggested Methods. Pergamon Press, London. Kundu J, Sarkar K, Singh AK (2016) Integrating structural and numerical solutions for road cut slope stability analysis-A case study, India. Rock Dynamics: From Research to. Engineering: Proceedings of the 2nd International Conference on Rock Dynamics ...

  12. Spider (Araneae) communities of scree slopes in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Klimeš, Leoš

    2005-01-01

    Roč. 33, č. 2 (2005), s. 280-289 ISSN 0161-8202 R&D Projects: GA AV ČR(CZ) IAA6007401 Institutional research plan: CEZ:AV0Z50070508; CEZ:AV0Z6005908 Keywords : scree slopes * environmental factors * ice formation Subject RIV: EG - Zoology Impact factor: 0.557, year: 2005

  13. Data compression by a decreasing slope-threshold test

    Science.gov (United States)

    Kleinrock, L.

    1973-01-01

    Resolution can be obtained at large compression ratios with method for selecting data points for transmission by telemetry in television compressed-data system. Test slope of raw data stream and compare it to symmetric pair of decreasing thresholds. When either threshold is exceeded, data are sampled and transmitted; thresholds are reset, and test begins again.

  14. Oscillating Nocturnal Slope Flow in a Coastal Valley

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Larsen, Søren Ejling; Mahrt, Larry

    1985-01-01

    Observations of slope flows in a coastal valley are analyzed. The diurnal variation of upslope and downslope flows depends on season in a systematic way which appears to be related to the high latitude of the observational site and the presence of a nearby layer of marine air. Summer nocturnal flow...

  15. Air quality in bedded mono-slope beef barns

    Science.gov (United States)

    Bedded mono-slope barns are becoming more common in the upper Midwest. Because these are new facilities, little research has been published regarding environmental quality, building management and animal performance in these facilities. A team of researchers from South Dakota State University, USDA ...

  16. How the spatial variation of tree roots affects slope stability

    Science.gov (United States)

    Mao, Zhun; Stokes, A.; Jourdan, C.; Rey, H.; Courbaud, B.; Saint-André, L.

    2010-05-01

    It is now widely recognized that plant roots can reinforce soil against shallow mass movement. Although studies on the interactions between vegetation and slope stability have significantly augmented in recent years, a clear understanding of the spatial dynamics of root reinforcement (through additional cohesion by roots) in subalpine forest is still limited, especially with regard to the roles of different forest management strategies or ecological landscapes. The architecture of root systems is important for soil cohesion, but in reality it is not possible to measure the orientation of each root in a system. Therefore, knowledge on the effect of root orientation and anisotropy on root cohesion on the basis of in situ data is scanty. To determine the effect of root orientation in root cohesion models, we investigated root anisotropy in two mixed, mature, naturally regenerated, subalpine forests of Norway spruce (Picea abies), and Silver fir (Abies alba). Trees were clustered into islands, with open spaces between each group, resulting in strong mosaic heterogeneity within the forest stand. Trenches within and between clusters of trees were dug and root distribution was measured in three dimensions. We then simulated the influence of different values for a root anisotropy correction factor in forests with different ecological structures and soil depths. Using these data, we have carried out simulations of slope stability by calculating the slope factor of safety depending on stand structure. Results should enable us to better estimate the risk of shallow slope failure depending on the type of forest and species.

  17. Slope Stability Analysis Using Slice-Wise Factor of Safety

    Directory of Open Access Journals (Sweden)

    Yu Zhao

    2014-01-01

    Full Text Available The concept of slice-wise factor of safety is introduced to investigate the state of both the whole slope and each slice. The assumption that the interslice force ratio is the same between any two slices is made and the eccentric moment of slice weight is also taken into account. Then four variables equations are formulated based on the equilibrium of forces and moment and the assumption of interslice forces, and then the slice-wise factor of safety along the slip surface can be obtained. The active and passive sections of the slope can be determined based on the distribution of factor of safety. The factor of safety of the whole slope is also defined as the ratio of the sum of antisliding force to the sum of sliding force on the slip surface. Two examples with different slip surface shapes are analysed to demonstrate the usage of the proposed method. The slice-wise factor of safety enables us to determine the sliding mechanism and pattern of a slope. The reliability is verified by comparing the overall factor of safety with that calculated by conventional methods.

  18. Slope histogram distribution-based parametrisation of Martian geomorphic features

    Science.gov (United States)

    Balint, Zita; Székely, Balázs; Kovács, Gábor

    2014-05-01

    The application of geomorphometric methods on the large Martian digital topographic datasets paves the way to analyse the Martian areomorphic processes in more detail. One of the numerous methods is the analysis is to analyse local slope distributions. To this implementation a visualization program code was developed that allows to calculate the local slope histograms and to compare them based on Kolmogorov distance criterion. As input data we used the digital elevation models (DTMs) derived from HRSC high-resolution stereo camera image from various Martian regions. The Kolmogorov-criterion based discrimination produces classes of slope histograms that displayed using coloration obtaining an image map. In this image map the distribution can be visualized by their different colours representing the various classes. Our goal is to create a local slope histogram based classification for large Martian areas in order to obtain information about general morphological characteristics of the region. This is a contribution of the TMIS.ascrea project, financed by the Austrian Research Promotion Agency (FFG). The present research is partly realized in the frames of TÁMOP 4.2.4.A/2-11-1-2012-0001 high priority "National Excellence Program - Elaborating and Operating an Inland Student and Researcher Personal Support System convergence program" project's scholarship support, using Hungarian state and European Union funds and cofinances from the European Social Fund.

  19. Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B

    2008-08-15

    Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

  20. 30 CFR 716.2 - Steep-slope mining.

    Science.gov (United States)

    2010-07-01

    ... original contour restoration requirements. (1) This section applies to surface coal mining operations on... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Steep-slope mining. 716.2 Section 716.2 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR INITIAL PROGRAM...