Element partitioning between magnesium silicate perovskite and ferropericlase: New insights into bulk lower-mantle geochemistry     

Anne-Line Auzende  James Badro  Frederick J. Ryerson  Peter K. Weber  Stewart J. Fallon  Ahmed Addad  Julien Siebert  Guillaume Fiquet   《Earth and Planetary Science Letters》2008,269(1-2):164-174

In this study, we investigated iron–magnesium exchange and transition-metal trace-element partitioning between magnesium silicate perovskite (Mg,Fe)SiO₃ and ferropericlase (Mg,Fe)O synthetised under lower-mantle conditions (up to 115 GPa and 2200 K) in a laser-heated diamond anvil cell. Recovered samples were thinned to electron transparency by focused ion beam and characterized by analytical transmission electron microscopy (ATEM) and nanometer-scale secondary ion mass spectroscopy (nanoSIMS). Iron concentrations in both phases were obtained from X-ray energy dispersive spectroscopy measurements and nanoSIMS. Our results are the first to show that recently reported spin-state and phase transitions in the lower mantle directly affect the evolution of Fe–Mg exchange between both phases. Mg-perovskite becomes increasingly iron-depleted above 70–80 GPa possibly due to the high spin–low spin transition of iron in ferropericlase. Conversely, the perovskite to post-perovskite transition is accompanied by a strong iron enrichment of the silicate phase, ferropericlase remaining in the Fe-rich phase though. Nanoparticles of metallic iron were observed in the perovskite-bearing runs, suggesting the disproportionation of ferrous iron oxide, but were not observed when the post-perovskite phase was present. Implications on the oxidation state of the Earth and core segregation will be discussed. Transition trace-element (Ni, Mn) concentrations (determined with the nanoSIMS) show similar trends and could thus be used to trace the origin of diamonds generated at depth. This study provides new results likely to improve the geochemical and geophysical models of the Earth's deep interiors.  相似文献   

Integrating Borehole Logs and Aquifer Tests in Aquifer Characterization   总被引：4，自引：0，他引：4  

Frederick L. Paillet  Ronald S. Reese 《Ground water》2000,38(5):713-725

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Feeding habits of red drum (Sciaenops ocellatus) in Galveston Bay, Texas: Seasonal diet variation and predator-prey size relationships     

Frederick S. Scharf  Kurtis K. Schlicht 《Estuaries and Coasts》2000,23(1):128-139

Feeding habits, seasonal diet variation, and predator size-prey size relationships of red drum (Sciaenops ocellatus) were investigated in Galveston Bay, Texas through stomach contents analysis. A total of 598 red drum ranging from 291–763 mm total length were collected and their stomach contents analyzed during fall 1997 and spring 1998. The diet of red drum showed significant seasonal patterns, and was dominated by white shrimp (Penaeus setiferus) during fall and gulf menhaden (Brevoortia patronus) during spring. Blue crab (Callinectes sapidus) was an important component of red drum diets during both seasons. Significant differences existed between prey types consumed during fall and spring as red drum diet reflected seasonal variation in prey availability. Predictive regression equations were generated to estimate original carapace width of blue crabs from several measurements taken from carapace fragments recovered in red drum stomachs. Regressions were highly significant (r²>0.97) and increased the number of blue crabs with size information nearly three fold. Predator size-prey size relationships were determined for red drum feeding on white shrimp, gulf menhaden, and blue crab. Although regression slopes were statistically significant, prey sizes increased only slightly with increasing red drum size. Comparisons of prey sizes consumed by red drum with sizes occurring in the field indicate that red drum feed in nearshore shallow water habitats, which serve as nursery areas for many juvenile fishes and crustaceans. Our findings demonstrate that red drum feed on several prey species of commercial and recreational value and may have important effects on estuarine community structure.  相似文献   

Reducing the impacts of flood-induced reservoir turbidity on a regional water supply system     

Frederick N.-F. Chou  ChiaWen Wu 《Advances in water resources》2010

This paper proposed an integrated simulation model to incorporate the impact of flood-induced reservoir turbidity into water supply. The integrated model includes a regional water allocation model and a one-dimensional settling model of cohesive particles based on Kynch’s theory. It simulates the settling of sediment flocculation in a turbid reservoir. The restrictions of water supply during floods is mimicked by simulating turbidity profiles for control points and then quantifying the associated treatment capability of raw water in the regional water allocation model for each time step. This framework can simulate shortages caused by flood-induced high turbidity as well as extended droughts, thus provide a basis for comprehensive evaluations of emergent and regular water supply facilities. A case study of evaluating different measures to mitigate the impact of turbid reservoir on water supply in northern Taiwan is presented to demonstrate the efficacy of the proposed approach.  相似文献   

On the Separation of the Spectral Components of Polar Motion   总被引：1，自引：0，他引：1  

Frederick J. Wells  Michael A. Chinnery 《Geophysical Journal International》1973,34(2):179-192

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"Implications of observed and simulated ambient flow in monitoring wells," by Alper Elci, Fred J. Molz III, and W. R. Waldrop, November-December 2001 issue, v. 39, no. 6: 853-862     

Paillet FL 《Ground water》2004,42(1):137-138

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Reply to comment by Kick Hemker on "Evaluation of a pumping test of the Snake River Plain aquifer using an axial-flow numerical model"     

Gary?S.?JohnsonEmail author  Donna?M.?Cosgrove  David?B.?Frederick 《Hydrogeology Journal》2003,11(2):313-313

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REFERENTIAL TREATMENT     

Frederick E. Nelson  Briavel Holcomb 《The Professional geographer》1989,41(1):78-81

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ENHANCING HIGH SCHOOL GEOGRAPHY AT THE LOCAL LEVEL     

Frederick P. Stutz 《The Professional geographer》1985,37(4):391-395

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Rotational locks for near-symmetric satellites     

Frederick H. Lutze Jr.  Matt W. Abbitt Jr. 《Celestial Mechanics and Dynamical Astronomy》1969,1(1):31-35

The results of Chernous'ko are extended numerically in order to investigate the character of locked-in rotational motion for orbits of arbitrary eccentricity. It is found that for certain ranges of eccentricity, the rotational lock for the higher spin rates in stronger than that of a 1/1 rotational lock in a circular orbit. Furthermore the limiting values of the instantaneous spin rate of the satellite are established for any given rotational lock.  相似文献