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61.
Inflation along Kilauea's Southwest Rift Zone in 2006   总被引:1,自引:0,他引:1  
We report on InSAR and GPS results showing the first crustal inflation along the southwest rift zone at Kilauea volcano in over 20 years. Two independent interferograms (May 2–August 2, 2006 and June 22–Nov 7, 2006) from the ALOS PALSAR instrument reveal domal uplift located southwest of the main caldera. The uplift is bounded on the northeast by the caldera and follows the southwest rift zone for about 12 km. It is approximately 8 km wide. We use data derived from permanent GPS stations to calibrate the InSAR displacement data and estimate uplift of 7.7 cm during the first interferogram and 8.9 cm during the second with line-of-sight volumes of 2.8 × 106 m3 and 3.0 × 106 m3 respectively. The earthquake record for the periods before, during, and after inflation shows that a swarm of shallow earthquakes (z < 5 km) signaled the beginning of the uplift and that elevated levels of shallow seismicity along the rift zones occurred throughout the uplift period. GPS data indicate that the inflation occurred steadily over nine months between mid-January and mid-October, 2006 making injection of a sill unlikely. We attribute the inflation to recharge of a shallow ductile area under the SWRZ.  相似文献   
62.
The accurate measurement of suspended sediment (<200 μm) in aquatic environments is essential to understand and effectively manage changes to sediment, nutrient, and contaminant concentrations on both temporal and spatial scales. Commonly used sampling techniques for suspended sediment either lack the ability to accurately measure sediment concentration (e.g., passive sediment samplers) or are too expensive to deploy in sufficient number to provide landscape‐scale information (e.g., automated discrete samplers). Here, we evaluate a time‐integrated suspended sediment sampling technique, the pumped active suspended sediment (PASS) sampler, which collects a sample that can be used for the accurate measurement of time‐weighted average (TWA) suspended sediment concentration and sediment particle size distribution. The sampler was evaluated against an established passive time‐integrated suspended sediment sampling technique (i.e., Phillips sampler) and the standard discrete sampling method (i.e., manual discrete sampling). The PASS sampler collected a sample representative of TWA suspended sediment concentration and particle size distribution of a control sediment under laboratory conditions. Field application of the PASS sampler showed that it collected a representative TWA suspended sediment concentration and particle size distribution during high flow events in an urban stream. The particle size distribution of sediment collected by the PASS and Phillips samplers were comparable and the TWA suspended sediment concentration of the samples collected using the PASS and discrete sampling techniques agreed well, differing by only 4% and 6% for two different high flow events. We should note that the current configuration of the PASS sampler does not provide a flow‐weighted measurement and, therefore, is not suitable for the determination of sediment loads. The PASS sampler is a simple, inexpensive, and robust in situ sampling technique for the accurate measurement of TWA suspended sediment concentration and particle size distribution.  相似文献   
63.
The Budyko framework characterizes landscape water cycles as a function of climate. We used this framework to identify regions with contrasting hydroclimatic change during the past 50 years in Sweden. This analysis revealed three distinct regions: the mountains, the forests, and the areas with agriculture. Each region responded markedly different to recent climate and anthropogenic changes, and within each region, we identified the most sensitive subregions. These results highlight the need for regional differentiation in climate change adaptation strategies to protect vulnerable ecosystems and freshwater resources. Further, the Budyko curve moved systematically towards its water and energy limits, indicating augmentation of the water cycle driven by changing vegetation, climate and human interactions. This finding challenges the steady state assumption of the Budyko curve and therefore its ability to predict future water cycles. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
64.
The H. J. Andrews Experimental Forest (HJA) encompasses the 6400 ha Lookout Creek watershed in western Oregon, USA. Hydrologic, chemistry and precipitation data have been collected, curated, and archived for up to 70 years. The HJA was established in 1948 to study the effects of harvest of old-growth conifer forest and logging-road construction on water quality, quantity and vegetation succession. Over time, research questions have expanded to include terrestrial and aquatic species, communities and ecosystem dynamics. There are nine small experimental watersheds and 10 gaging stations in the HJA, including both reference and experimentally treated watersheds. Gaged watershed areas range from 8.5 to 6242 ha. All gaging stations record stage height, water conductivity, water temperature and above-stream air temperature. At nine of the gage sites, flow-proportional water samples are collected and composited over 3-week intervals for chemical analysis. Analysis of stream and precipitation chemistry began in 1968. Analytes include dissolved and particulate species of nitrogen and phosphorus, dissolved organic carbon, pH, specific conductance, suspended sediment, alkalinity, and major cations and anions. Supporting climate measurements began in the 1950s in association with the first small watershed experiments. Over time, and following the initiation of the Long Term Ecological Research (LTER) grant in 1980, infrastructure expanded to include a set of benchmark and secondary meteorological stations located in clearings spanning the elevation range within the Lookout Creek watershed, as well as a large number of forest understory temperature stations. Extensive metadata on sensor configurations, changes in methods over time, sensor accuracy and precision, and data quality control flags are associated with the HJA data.  相似文献   
65.
A study using multiple techniques provided insight into tectonic influences on ground water systems; the results can help to understand ground water systems in the tectonically active western United States and other parts of the world. Ground water in the San Bernardino Valley (Arizona, United States and Sonora, Mexico) is the main source of water for domestic use, cattle ranching (the primary industry), and the preservation of threatened and endangered species. To improve the understanding of ground water occurrence, movement, and sustainability, an investigation was conducted using a number of complementary methods, including major ion geochemistry, isotope hydrology, analysis of gases dissolved in ground water, aquifer testing, geophysics, and an examination of surface and subsurface geology. By combining information from multiple lines of investigation, a more complete picture of the basin hydrogeology was assembled than would have been possible using fewer methods. The results show that the hydrogeology of the San Bernardino Valley is markedly different than that of its four neighboring basins in the United States. The differences include water quality, chemical evolution, storage, and residence time. The differences result from the locally unique geology of the San Bernardino Valley, which is due to the presence of a magmatically active accommodation zone (a zone separating two regions of normal faults with opposite dips). The geological differences and the resultant hydrological differences between the San Bernardino Valley and its neighboring basins may serve as a model for the distinctive nature of chemical evolution of ground water in other basins with locally distinct tectonic histories.  相似文献   
66.
This study focuses on how the variability of land surface temperature and vegetation density at the SGP ARM-CART site changes over episodic (day to day) and seasonal time scales using AVHRR satellite data. Four drying periods throughout the year are analyzed. Land surface temperature had an erratic relationship with time exhibiting no deterministic pattern from day-to-day or season-to-season. Furthermore, it did not exhibit spatial pattern persistence. On the other hand, vegetation density had a consistent spatial pattern and temporal decay during average length drying periods (less than 7 days) as well as within a season. However, there were distinct differences in the seasonal pattern of variation between winter and growing seasons. In addition, the paper highlights a methodology to quantify the relationships that exist at the land surface between the primary parameter of interest and the controlling variables.  相似文献   
67.
MONITORING SAMPLING PROTOCOL CONSIDERATIONS   总被引:1,自引:0,他引:1  
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68.
An international demonstration (RD&D) project for ocean storage of radioactive wastes should be proposed, to study the feasibility of the concept of ocean storage of nuclear waste. This international project should utilize the scientific, engineering and technical capabilities of selected universities, oceanographic institutions, NGOs and industries. This project would need to be an independent (non-governmental) study, utilizing the capabilities of selected universities, oceanographic institutions, environmental NGOs (Non-Governmental Organizations) and industries. Scientists and engineers first need to conduct an engineering, environmental, and economic feasibility study of the concept. The goal of the project would be to determine if ocean-based storage reduced the risks to the environment and public health to a greater degree than land-based storage. This would require comparing the risks and factors involved and making the data and information available to anyone, anywhere, anytime on the internet. The mere presence of an investigation of the ocean storage option could facilitate scientific and engineering competition between the two options, could subsequently reduce environmental and public risks and provide better protection and cost benefits in the system utilized. One of the primary concerns of the scientific community would be related to the sensitivity and precision of the monitoring of individaul containers on the ocean bottom. An advantage of the land-based option is that if there is a release, its presence could be detected at very low levels and be contained in the storage facility. On the ocean bottom, a release from a container might not be easily detected due to dispersion. Therefore the containment system would have to be a system within a system with monitoring between the two providing greater protection. Ocean storage may have greater technical and political hurdles than land-based options, but it may provide greater protection over time, because it negates the threat of terrorism, it therefore merit further study. In the future if the use of nuclear energy and nuclear wastes increases, the global society could benefit from this international project, because it could reduce environmental and public health risks and promote energy independence.  相似文献   
69.
As the world's climate continues to change there is concern that this may cause malaria to spread to new areas. Here we examine whether past changes in temperature, in addition to social changes, may have affected malaria in England. Our analysis indicates that cold summers experienced during the 1800s may have contributed to the disappearance of this disease from the country. As our summers become progressively warner it is unlikely that malaria will become firmly re-established on these shores, although the possibility of future outbreaks should not be ignored.  相似文献   
70.
PAH exposure was assessed in fish from Arthur Harbor, Antarctica and sites remote from human activities by measuring the concentrations of polycyclic aromatic hydrocarbon (PAH) metabolites in bile and PAH in tissues and stomach contents. The highest concentrations of biliary metabolites and tissue PAH were present in fish captured near an Argentine supply ship (Bahia Paraiso) that ran aground in Arthur Harbor in 1989. The presence of biliary PAH metabolites in fish collected near Palmer Station, a small US scientific station in Arthur Harbor, suggests low level exposure to contaminants. However, PAH tissue concentrations in fish from Palmer Station were similar to those from remote sites. Both tissue PAH and metabolite concentrations were low in fish captured at sites remote from human activities. The confirmation of PAH metabolites in the bile of fish from Arthur Harbor is direct evidence that the presence of humans has resulted in Antarctic fish being exposed to petroleum-derived PAH.  相似文献   
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