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1.
Geographically or sociologically defined resource management units, such as buffer zones or community resource management territories, seek to harmonize local land–use practices with protected–area management objectives. The geographically restricted nature of these models often results in simplistic representations of society–nature relations over time and space. Conservation areas are misrepresented as ecologically and socially homogeneous, as well as politically neutral. This study examines the limits of a spatially defined conservation and development project designed around the physical geographical unit of the watershed at Lake Nakuru National Park, Kenya. It argues that politically motivated violence that has plagued the area since the early 1990s has severely undermined the suitability of such narrowly defined conservation territories. Specifically, the case study points to the permeability of the Lake Nakuru watershed to national and regional political forces that ultimately constrain participation in conservation activities. The spaces of conservation and development must be enlarged to include these extralocal arenas and processes if environmental problems are to be effectively addressed. 相似文献
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William A. Bassett John M. Bird Maura S. Weathers D.L. Kohlstedt 《Physics of the Earth and Planetary Interiors》1980,23(4):255-261
Josephinite, a complex, metal-bearing rock from the region of the Josephine Peridotite in southwest Oregon, contains FeNiCo metal alloy phases having exsolution textures. Scanning and transmission electron microscopy have revealed Widmanstaetten patterns in which the lamellae are polysynthetically twinned, ordered, face-centered-cubic FeNi3 surrounded by untwinned, ordered, face-centered-cubic FeNi3 and body-centered-cubic FeCo. These exsolution textures require a temperature in excess of 500°C for their formation. This is consistent with a mantle derivation of josephinite prior to obduction of the peridotite in one of the Klamath ophiolites. 相似文献
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William A. Bassett 《Physics of the Earth and Planetary Interiors》1980,23(4):337-340
The Wilson electron synchrotron at Cornell University has recently undergone modifications which enable it to produce a highly collimated X-ray beam of 1015 photons (s mrad. 10% bandwidth)?1 in the range from 1 to 40 keV (12.4 to 0.31 Å wavelength). It is expected that a monochromatic beam produced from this source will have at least a hundred times the intensity of the X-rays from a rotating anode source. It is hoped that the use of a position-sensitive detector will improve the detection efficiency by another factor of a hundred over photographic film. If these improvements are realized, it should be possible to conduct real-time or nearly real-time diffraction experiments in the diamond anvil cell. The technique will be used to collect data for experiments in which slower data collecting would mean missing transient phenomena. The technique will also be useful for making studies during conditions that cause deterioration of the experimental apparatus such as graphitization of the diamonds or creep of the metal parts. 相似文献
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Ian Shennan Sarah Hamilton Caroline Hillier Amanda Hunter Ruth Woodall Sarah Bradley Glenn Milne Anthony Brooks Sophie Bassett 《第四纪科学杂志》2006,21(6):601-613
Observations of relative sea‐level change and local deglaciation in western Scotland provide critical constraints for modelling glacio‐isostatic rebound in northern Britain over the last 18 000 years. The longest records come from Skye, Arisaig and Knapdale with a shorter, Holocene, record from Kintail. Biostratigraphic (diatom, pollen, dinoflagellate, foraminifera and thecamoebian), lithological and radiocarbon analyses provide age and elevation parameters for each sea‐level index point. All four sites reveal relative sea‐level change that is highly non‐monotonic in time as the local vertical component of glacio‐isostatic rebound and eustasy (or global meltwater influx) dominate at different periods. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Ian Shennan Sarah Bradley Glenn Milne Anthony Brooks Sophie Bassett Sarah Hamilton 《第四纪科学杂志》2006,21(6):585-599
While contributing <1 m equivalent eustatic sea‐level rise the British Isles ice sheet produced glacio‐isostatic rebound in northern Britain of similar magnitude to eustatic sea‐level change, or global meltwater influx, over the last 18 000 years. The resulting spatially variable relative sea‐level changes combine with observations from far‐field locations to produce a rigorous test for quantitative models of glacial isostatic adjustment, local ice‐sheet history and global meltwater influx. After a review of the attributes of relative sea‐level observations significant for constraining large‐scale models of the isostatic adjustment process we summarise long records of relative sea‐level change from the British Isles and far‐field locations. We give an overview of different global theoretical models of the isostatic adjustment process before presenting intercomparisons of observed and predicted relative sea levels at sites in the British Isles and far‐field for a range of Earth and ice model parameters in order to demonstrate model sensitivity and the resolving power available from using evidence from the British Isles. For the first time we show a good degree of fit between relative sea‐level observations and predictions that are based upon global Earth and ice model parameters, independently derived from analysis of far‐field data, with a terrain‐corrected model of the British Isles ice sheet that includes extensive glaciation of the North Sea and western continental shelf, that does not assume isostatic equilibrium at the Last Glacial Maximum and keeps to trimline constraints of ice surface elevation. We do not attempt to identify a unique solution for the model lithosphere thickness parameter or the local‐scale detail of the ice model in order to provide a fit for all sites, but argue that the next stage should be to incorporate an ice‐sheet model that is based on quantitative, glaciological model simulations. We hope that this paper will stimulate this debate and help to integrate research in glacial geomorphology, glaciology, sea‐level change, Earth rheology and quantitative modelling. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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A field study was conducted using a combination of intrinsic and artificial tracers to estimate travel times and dilution during transport of infiltrate from a reclaimed water infiltration basin to nearby monitoring wells. A major study objective was to validate boric acid enriched in (10)B as an artificial tracer. Basin 10E at the Rio Hondo Spreading Grounds in Whittier, California, was the site of the test. The basin normally receives a mixture of treated municipal waste water, purchased State Project water, and local runoff from the San Gabriel River. Approximately 3.5 kg of (10)B-enriched boric acid was dispersed among 2.05 x 10(5) m(3) of basin water to initiate the experiment. The resultant median delta(11)B in the infiltration basin was -71 per thousand. Prior to tracer addition, the basin water had an intrinsic delta(11)B of +2 per thousand. Local monitoring wells that were used to assess travel times had delta(11)B values of +5 per thousand and +8 per thousand at the time of tracer addition. Analytic results supported an assumption that boron is conserved during ground water transport and that boron enriched in (10)B is a useful artificial tracer. Several intrinsic tracers were used to reinforce the boric acid tracer findings. These included stable isotopes of oxygen (delta(18)O) and hydrogen (deltaD), sulfate concentration, and the boron to chloride ratio. Xenon isotopes, (136)Xe and (124)Xe, also supported boron isotope results. Xenon isotopes were added to the recharge basin as dissolved gases by investigators from the Lawrence Livermore National Laboratory. 相似文献
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A critical evaluation of the available measurements for the stable isotopes of boron 总被引:1,自引:0,他引:1
R.L. Bassett 《Applied Geochemistry》1990,5(5-6)
The reported measurements for the stable isotopes of B (11B and 10B) in natural materials are compiled, critically reviewed and evaluated. The selected values along with a discussion of the error, indicate the potential exists for using B isotopes in interpreting geochemical environments. The isotopic values for δ11B range from -31%0 for terrestrial rocks to +40%0 for sea water, relative to NBS SRM-951 which has a reported 11B/10B ratio of 4.04362 ± 0.00137 (2σ). Furtherm the isotope ratios generally form a narrow cluster of values for specific rock types. In some instances the reported δ11B may be shifted substantially from the mean of “unaltered” rock as a result of weathering or reaction such as the progressive enrichment of δ11B in marine sediments over time due to reaction with sea water.An application of widespread interest is the use of B isotopes in environmental studies. Boron is a contaminant derived from numerous sources such as municipal and industrial waste. The δ11B in these wastes or processed waters is often significantly different from the δ11B of the local ground-water, which will likely reflect the δ11B values of the nearby rocks. This modification by contaminated water can be >20%0 different from the δ11B of the unaffected water, providing a useful tool in delineating the source of contamination and the direction of migration. 相似文献