Local Perceptions of the Sustainability of Alaska’s Highly Contested Cook Inlet Salmon Fisheries     

Philip A. Loring  Hannah L. Harrison  S. Craig Gerlach 《社会与自然资源》2014,27(2):185-199

Using a mixed set of ethnographic methods including interviews and a structured survey, we evaluate local perceptions about the sustainability of salmon fisheries among fishers of the Cook Inlet region of Alaska. A majority of residents report participating in these fisheries, but we find significant disagreement about their sustainability. Household income and the types of fishing practiced both influence people's responses, and many implicated specific user groups for overharvesting and/or for receiving unfair catch allocations. Drawing on the theoretical areas of information theory and political ecology, we argue that these findings reveal a complex interplay among the practical, social, and political aspects of how local resource users, or “local experts,” develop and communicate their assessments of ecological conditions in a context of conflict. We conclude with notes on future research as it relates to the successful design of local-management and co-management solutions, especially in settings where resources are contested by stakeholders.  相似文献   

Evaluating Volumetric Glacier Change Methods Using Airborne Laser Scanning Data     

Philip Claudio Joerg  Michael Zemp 《Geografiska Annaler: Series A, Physical Geography》2014,96(2):135-145

Assessments of geodetic volume change are widely used in glaciology and have a long tradition dating back to the nineteenth century. Over time, the geodetic method and corresponding data storage have been developed further, but the resulting methodological heterogeneity can lead to errors that are difficult to separate from other survey uncertainties. In this study we used high‐resolution airborne laser scanning data from the Findelengletscher in the Swiss Alps to evaluate state‐of‐the‐art volumetric glacier change methods. For the first time we have been able to simulate errors arising from different geodetic methods and spatial resolutions. The evaluation showed that, although the digital elevation models were perfectly co‐registered, systematic and random method‐ and scale‐dependent errors still occurred. These errors have an impact on the resulting volume changes at lower spatial resolutions and may lead to exponentially larger uncertainties. Volume changes from contour methods provided reasonably accurate results, while volumetric change assessments from central profile lines were especially prone to biases at any scale.  相似文献   

Commercial Possibilities for Stranded Conventional Gas from Alaska’s North Slope     

Emil D. Attanasi  Philip A. Freeman 《Natural Resources Research》2014,23(1):175-193

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.  相似文献   

Lithium isotopes as indicators of meteorite parent body alteration     

Mark A. Sephton  Rachael H. James  Manuela A. Fehr  Philip A. Bland  Matthieu Gounelle 《Meteoritics & planetary science》2013,48(5):872-878

Hydrothermal processing on planetesimals in the early solar system produced new mineral phases, including those generated by the transformation of anhydrous silicates into their hydrated counterparts. Carbonaceous chondrites represent tangible remnants of such alteration products. Lithium isotopes are known to be responsive to aqueous alteration, yet previously recognized variability within whole rock samples from the same meteorite appears to complicate the use of these isotopes as indicators of processing by water. We demonstrate a new way to use lithium isotopes that reflects aqueous alteration in carbonaceous chondrites. Temperature appears to exert a control on the production of acetic acid‐soluble phases, such as carbonates and poorly crystalline Fe‐oxyhydroxides. Temperature and degree of water‐rock interaction determines the amount of lithium isotope fractionation expressed as the difference between whole rock and acetic acid‐leachable fractions. Using these features, the type 1 chondrite Orgueil (δ⁷Li_{(whole rock)} = 4.3‰; Δ⁷Li_{(acetic‐whole)} = 1.2‰) can be distinguished from the type 2 chondrites Murchison (δ⁷Li_{(whole rock)} = 3.8; Δ⁷Li_{(acetic‐whole)} = 8.8‰) and carbonate‐poor Tagish Lake (δ⁷Li_{(whole rock)} = 4.3; Δ⁷Li_{(acetic‐whole)} = 9.4‰). This initial study suggests that lithium isotopes have the potential to reveal the role of liquid water in the early solar system.  相似文献   

Models of near-bed dynamics and sediment movement at the Iberian margin     

Alan M. Davies  Jiuxing Xing  John M. Huthnance  Philip Hall  Laurenz Thomsen 《Progress in Oceanography》2002,52(2-4)

A three dimensional time-dependent baroclinic hydrodynamic model, including sediment transport and incorporating a turbulence energy sub-model, is used in cross sectional form to examine sediment movement at the shelf edge off North West Iberia at 42°40.5’N where measurements were made as part of the OMEX-II programme. These calculations are complemented by a simpler, in essence time-independent model, which is used to examine the sensitivity of the sediment distribution over the slope (from a shelf-break source) to changes in the specified values of horizontal and vertical diffusion coefficients. The philosophy of the paper is to use idealized tidal, wind and wind wave forcing to examine changes in sediment distribution resulting from these processes. Calculations with the time-dependent and steady state models give insight into both the role of events and long-term effects. The steady state model focuses on the off-shelf region, whilst the time-dependent model considers on-shelf events.Tidal calculations showed that for the stratification used here the internal tide in the OMEX region was primarily confined to the shelf edge and ocean. A mean on-shelf sediment transport in the surface layer and off-shelf transport at the bed was found. Across-shelf circulations produced by up-welling/down-welling favourable winds gave rise to on-shelf/off-shelf currents in the bottom boundary layer with an opposite flow in the surface layer. In the case of an up-welling favourable wind, sediment suspension was at a maximum in the near coastal region, with sediment being advected off shore in the surface layer. With a down-welling favourable wind, surface sediment was advected towards the shore, but there was offshore transport at the bed. Near the shelf edge any upwelling flow had the tendency to return this sediment to the surface layer from whence it was transported on-shore. So in essence the sediment was trapped within an on-shelf circulation cell. Wind waves effects increased the total bed stress and hence the sediment concentration and its transport, although its pattern was determined by tidal and wind forcing.The time independent model with increased/decreased lateral diffusivity gave an enhanced/reduced horizontal sediment distribution for a given settling velocity. As the settling velocity increases, the down-slope movement of sediment is increased, with a reduction in the thickness of the near-bed sediment layer, but with little change in its horizontal extent.  相似文献   

A derivation of the Isted formula for average mineral grade of a triangular prism     

D. F. Watson  G. M. Philip 《Mathematical Geology》1986,18(3):329-333

The Isted formula, which provides an exact calculation of the spatial average of mineral grade in a triangular prism under the assumption of linear change, is derived, and its limitations outlined. This formula may be used to estimate the mean of any trivariate function whenever variation in the vertical direction can be considered negligible.  相似文献   

An atlas of photospheric magnetic field observations and computed coronal magnetic fields: 1976–1985     

J. Todd Hoeksema  Philip H. Scherrer 《Solar physics》1986,105(1):205-211

Daily magnetogram observations of the large-scale photospheric magnetic field have been made at the John M. Wilcox Solar Observatory at Stanford since May of 1976. These measurements provide a homogeneous record of the changing solar field through most of solar cycle 21.Using the photospheric data, the configuration of the coronal and heliospheric fields can be calculated using a Potential Field - Source Surface model. This provides a three - dimensional picture of the heliospheric field evolution during the solar cycle.In this note we announce the publication of UAG Report No. 94, an Atlas containing the complete set of synoptic charts of the measured photospheric magnetic field, the computed field at the source surface, and the coefficients of the multipole expansion of the coronal field. The general underlying structures of the solar and heliospheric fields, which determine the environment for solar-terrestrial relations and provide the context within which solar activity related events occur, can be approximated from these data.  相似文献   

Biomonitoring of heavy metal availability in the marine environment   总被引：1，自引：0，他引：1  

Philip S. Rainbow 《Marine pollution bulletin》1995,31(4-12)

Biomonitors can be used to establish geographical and/or temporal variations in the bioavailabilities of heavy metals in the marine environment, offering time-integrated measures of those portions of the total ambient metal load that are of direct ecotoxicological relevance. Heavy metal biomonitors need to conform to certain required characteristics, not least being metal accumulators. Use of a suite of biomonitors allows recognition of the presence and relative magnitude of different metal sources. For example, a macrophytic alga responds essentially to dissolved metal sources only, a suspension feeder like a mussel responds to metal sources in dissolved and suspended phases, and a deposit feeder responds to metal available in the sediment. Examples are given of suitable heavy metal biomonitors in the coastal waters of Europe, New Zealand, Hong Kong and China. It is not valid to compare absolute accumulated metal concentrations in biomonitors interspecifically, although interspecific comparisions of rank orders do allow cross correlations of relative bioavailabilities of heavy metals to different biomonitors at the same sites. There is a need to identify widespread cosmopolitan biomonitors to allow intra-specific comparisons of bioavailabilities between geographical areas. Such cosmopolitan biomonitors may include the alga Ulva lactuca, mussels of the genera Mytilus and Perna, the oysters Ostrea and Crassostrea, barnacles like Balanus amphitrite and Tetraclita squamosa, and the talitrid amphipod Platorchestia platensis. A major caveat in the use of such cosmopolitan biomonitors remains the need for reliable, specific taxonomic identification.  相似文献   

Alkali exchange equilibria between a silicate melt and coexisting magmatic volatile phase: an experimental study at 800°C and 100 MPa     

Mark R. Frank  Philip M. Piccoli 《Geochimica et cosmochimica acta》2003,67(7):1415-1427

Many experimental studies have been performed to evaluate the composition of coexisting silicate melts and magmatic volatile phases (MVP). However, few studies have attempted to define the relationship between melt chemistry and the acidity of a chloride-bearing fluid. Here we report data on melt composition as a function of the HCl concentration of coexisting brines. We performed 35 experimental runs with a NaCl-KCl-HCl-H₂O brine (70 wt% NaCl [equivalent])-silicate melt (starting composition of Qtz_0.38Ab_0.33Or_0.29, anhydrous) assemblage at 800°C and 100 MPa. We determined an apparent equilibrium constant