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41.
Dawn A. Zemo 《Ground Water Monitoring & Remediation》2009,29(3):77-83
This article provides actual site data that confirm that turbid ground water samples collected from within the smear zone at petroleum release sites can be significantly biased high by the inclusion of a nondissolved component that is an artifact of the sampling process. Side-by-side comparisons show that reducing sample turbidity can result in significant reductions of reported concentrations for the ground water samples and that the lower turbidity results are more representative of the petroleum actually dissolved in the ground water. Depending on site-specific factors, ground water sample turbidity can be reduced by four field-based and two laboratory-based methods. These methods should be used routinely at sites where turbid samples with a nondissolved component are being collected. 相似文献
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Lenz Dawn D. DeLuca Edward E. Golub Leon Rosner Robert Bookbinder Jay A. Litwin Christof Reale Fabio Peres Giovanni 《Solar physics》1999,190(1-2):131-138
An initial study of long-lived loops observed with TRACE (Lenz et al., 1999) shows that they have no significant temperature stratification and that they are denser than the classic loop model
predicts. Models that agree better with the observations include a loop consisting of a bundle of filaments at different temperatures
and a loop with momentum input by MHD waves. Some implications for coronal heating models and mechanisms are discussed. 相似文献
45.
Geotechnical properties of carbonate sediments result from several factors such as the particular constituents comprising
the sediment, the mineralogy, fabric, and effective stress. Investigating the effects of increasing effective stress by mechanical
consolidation using permeability, porosity, and porometry determinations reveals fabric changes that could not be determined
in scanning electron micrographs. Porometry changes, determined using an image analyzer, are a function of matrix composition
and grain support. Samples that were predominantly matrix-supported exhibited an increase in pore numbers per unit area and
a pore size decrease resulting from consolidation. Samples composed predominantly of aragonite needle matrices displayed opposite
behavior. 相似文献
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Kevin P. Stephens Peter Fleischer Dawn Lavoie Charlotte Brunner 《Geo-Marine Letters》1997,17(4):299-305
Spatial variability of shallow-water carbonate sediments near Dry Tortugas, Florida, is scale-dependent. Wet bulk density,
grain density, porosity, compressional wave velocity, and grain size variability generally increase down to 2.4 m vertically
and 850 m laterally. Grain size is most variable, followed by porosity, wet bulk density, compressional wave velocity, and
grain density bothvertically and laterally, consistent with Walther’s Law. Variability was empirically modeled by linear regression
analysis to predict variability based on scale, characterize sediment property variability, and quantify sedimentisotropy. 相似文献
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Marine environments, key life-support systems for the earth, are under severe threat. Issues associated with managing these common property resources are complex and interrelated. Networks of marine reserves can be valuable for mitigating threats to marine systems, yet the successful design and implementation of such networks has been limited. Efficient ways to conserve marine environments are urgently needed. This Focus Section of The Professional Geographer explores the development of marine reserve networks based on geomorphology, fish biology, ecological connectivity, and appropriate governance. The articles in this Focus Section offer examples of the following: (1) distinctive reef geomorphology dictating the spawning locations of reef fishes, which in turn serve as critical source sites for the replenishment of distant reefs by means of larval transport; (2) an example of a simplified oceanographic model that predicts larval transport from fish breeding sites to important nursery areas; and (3) a case study of the development of a marine reserve network that illustrates key elements of a successful strategy. In sum, this Focus Section offers case studies that show the value of marine geomorphology, oceanographic connectivity, and stakeholder involvement as key elements of multidisciplinary geographic studies applied to the design of marine reserve networks. Geographers can further contribute to the conservation and management of coastal and marine ecosystems in many ways that involve subdisciplines of remote sensing and geographic information systems, political and economic geography, political ecology, and ethnography. 相似文献
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