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431.
A parameter called ΔO2? is defined as the difference between the Gibbs energy of formation from the elements of a crystalline oxide and the Gibbs energy of formation from the elements of its cation in aqueous solution (per O2? in the oxide). Another parameter called Δ hydroxide is defined as the difference between the Gibbs energies of formation of an hydroxide and its constituent oxides, H2O oxide being considered as ice. A linear equation for 32 hydroxides, using these two parameters is: Δhydroxide = ?0.210 (ΔO2? cation ? ΔO2? H+). This relation can also be expressed in terms of solution energies. The solution energy of an hydroxide is a linear function of the solution energy of the corresponding oxide. The equation above can be used to predict values for Gibbs energies of formation of hydroxides, oxides or aqueous cations and to test the consistency of existing Gibbs energy values. 相似文献
432.
433.
434.
Stability constants of hydroxocomplexes of Al(III):Al(OH)2+ and A1(OH)4? have been measured in the 20–70°C temperature range by reactions involving only dissolved species. The stability constant of the first complex ion is studied by measuring pH of solutions of aluminium salts at several concentrations. of aluminate ion is deduced from equilibrium constants of the reaction between the trioxalato aluminium (III) complex ion and Al3+ in acid medium, and between the same complex ion and A1(OH)4? in alkaline medium. The K values and the associated ΔH are and ΔH1 = 11.8 Kcal; and ΔH4 = 42.45 Kcal. These last results are not in agreement with the values of recent tables for and of Al3+ and Al(OH)4?. We suggest a consistent set of data for dissolved and solid Al species and for some aluminosilicates. 相似文献
435.
Pierre Mechler Raouf Mseddi Emile Okal Jean-Louis Plantet Yves Rocard 《Physics of the Earth and Planetary Interiors》1974,8(3):269-276
In this paper, we give a model of the 600-km discontinuity under France, which explains large travel-time and amplitude anomalies on teleseisms as recorded in the French network. It features a large descent from the Ardennes to the Pyrénées, of which tectonic implications are discussed. 相似文献
436.
Yves Gallet Jean Besse Leopold Krystyn Jean Marcoux 《Earth and Planetary Science Letters》1996,140(1-4):113-122
Late Triassic magnetostratigraphic investigations in southwestern Turkey have suggested that parts of the Antalya Nappes are constituted of a melange of blocks originally deposited either in the vicinity of the northern tip of Arabia or, more surprisingly, directly north of India, in the southern hemisphere. In order to ascertain this result more clearly, we have correlated the Turkish series with Austrian sections of corresponding age from the Northern Calcareous Alps, for which the hemisphere of deposition is beyond doubt. The new magnetostratigraphic results obtained from the Scheiblkogel section (Austria) confirm the previously suggested middle to late Norian magnetic polarity sequence and support the heterogeneous character of the Antalya Nappes. 相似文献
437.
Jean. M. Dasch Abdul S. Abdul Devi N. Rai Thomas L. Gibson Noel Grosvenor 《Ground Water Monitoring & Remediation》1997,17(3):194-209
The soil and ground water at a General Motors plant site were contaminated with petroleum products from leaking underground storage tanks. Based on the initial assessment, the site was complex from the standpoint of geology (clay layers), hydrology (a recharge zone with a perched water table), and contaminant (approximately 4800 gallons of mixed gasoline and oil). After a thorough study of remedial alternatives, a synergistic remedial approach was adopted including pump and treat, product removal, vapor extraction, and bioventing. The system was designed and implemented at the site through 22 dual-extraction wells. Over a 21-month period, 4400 gallons of gasoline and oil were removed from the system, including 59 percent by vapor extraction, 28 percent by bioventing, and 13 percent by pump and treat. Synergism between the various remedial methods was demonstrated clearly. Ground water pump and treat lowered the water table, allowing air to flow for vapor extraction. The vacuum applied for vapor extraction increased the ground water removal rate and the efficiency of pump and treat. The vapor extraction system also added oxygen to the soil to stimulate aerobic biodegradation. 相似文献
438.
Anthony C. Harris W. James Dunlap Peter W. Reiners Charlotte M. Allen David R. Cooke Noel C. White Ian H. Campbell Suzanne D. Golding 《Mineralium Deposita》2008,43(3):295-314
Application of multiple chronometers (including U–Pb and 40Ar/39Ar geochronology and zircon and apatite (U–Th)/He thermochronology) to porphyry intrusions at the Bajo de la Alumbrera porphyry
copper–gold deposit, Argentina, reveals a complex history of reheating that spans millions of years. Previous U–Pb geochronology,
combined with our new 40Ar/39Ar data, shows that the multiple porphyritic intrusions at Bajo de la Alumbrera were emplaced during two episodes, the first
at about 8.0 Ma (P2 and associated porphyries) and the second about a million years later (Early and Late P3 porphyries).
Complex overprinting alteration events have obscured the earliest hydrothermal history of the deposit. By contrast, 40Ar/39Ar data reveal the close temporal relationship of ore-bearing potassic alteration assemblages (7.12 ± 0.13 Ma; biotite) to
the emplacement of the P3 intrusions. Consistent with low closure temperatures, younger ages have been determined for associated
hydrothermal alkali feldspar (6.82 ± 0.05 Ma and 6.64 ± 0.09 Ma). The temperature-sensitive Ar data also record an unexpected
prolonged cooling history (to below 200°C) extending to 5.9 Ma. Our data suggest that the Bajo de la Alumbrera system underwent
protracted cooling, after the collapse of the main hydrothermal system, or that one or more low-temperature (~100–200°C) reheating
events occurred after emplacement of the porphyritic intrusions at Bajo de la Alumbrera. These have been constrained in part
by our new 40Ar/39Ar data (including multidomain diffusion modeling) and (U–Th)/He ages. Single-grain (U–Th)/He ages (n = 5) for phenocrystic zircon from P2 and P3 intrusive phases bracket these thermal events to between 6.9 (youngest crystallization
of intrusion) and 5.1 Ma. Multidomain modeling of alkali feldspar data (from both igneous and hydrothermal crystals) is consistent
with the deposit cooling rapidly from magmatic temperatures to below about 300°C, with a more protracted history down to 150°C.
We conclude that the late-stage low-temperature (150 to 200°C) thermal anomaly localized at Bajo de la Alumbrera resulted
from radiation of heat and/or fluids sourced from deeper-seated magma bodies, emplaced beneath the deposit. To produce the
observed thermal longevity of the porphyry system, magma bodies underlying the Bajo de la Alumbrera deposit must have been
repeatedly replenished by new magma batches. Without replenishment, crystallization of the source magma will occur, and heat
release will stop, leading to rapid cooling (in less than ten thousand years). The influx of deep-seated magma may have caused
the development of late low-temperature hydrothermal alteration assemblages at Bajo de la Alumbrera, at the same time that
mineralization formed at Agua Rica, some 25 km away. All available chronologic data for the Bajo de la Alumbrera deposit suggest
that the hydrothermal system was active episodically over at least a three-million and possibly up to a four-million-year
period.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
439.
Groundwater origin and flow along selected transects in Ethiopian rift volcanic aquifers 总被引:1,自引:1,他引:0
Seifu Kebede Yves Travi Asfawossen Asrat Tamiru Alemayehu Tenalem Ayenew Zenaw Tessema 《Hydrogeology Journal》2008,16(1):55-73
The disruption of lithologies by cross-cutting faults and the variability in volcanic structures make the hydrogeology of the rifted volcanic terrain in Ethiopia very complex. Along two transects, selected due to their hydrogeologic characteristics, groundwater flow, depth of circulation and geochemical evolution have been conceptualized. The groundwater flow continuity between the high rainfall plateau bounding the rift and the rift valley aquifers depends principally on the nature of the bounding faults. Up to 50% of recharge to the rift aquifers comes from the plateau as groundwater inflow where the rift is cross cut by transverse fault zones. Recharge from the mountains is found to be insignificant where the rift is bounded by marginal grabens; channel loss and local precipitation are the principal sources of recharge to the rift aquifers in such cases. At a regional scale, there is a clear zonation in the geochemical compositions of groundwaters, the result of aquifer matrix composition differences. The environmental isotope results show that the majority of the aquifers contain modern groundwaters. In a few localities, particularly in thermal groundwaters representing deeper circulation, palaeo-groundwaters have been identified. Deeper groundwaters in the rift floor have a uniform 14C age ranging between 2,300 and 3,000 years. 相似文献
440.
A. Thamilselvan A. S. Nesaraj M. Noel 《International Journal of Environmental Science and Technology》2016,13(12):2961-2976
Most of the electrochemical studies related to porous carbon electrodes are those which can be used for either electrostatic energy storage or for energy conversion [using electrical double layer capacitor (EDLC)]. The techniques, such as electrodialysis, membrane filtration, advanced oxidation process, thermal evaporation, can be used now-a-days to treat salty water. Among which, capacitive deionization (CDI) has emerged as a novel cost effective and environment friendly desalination technology. CDI process involves the removal of inorganic ions from the salty water by applying an electrical potential between two porous carbon electrodes. Because of the passage of electrical potentials in the system, the unwanted ions present in the water sample will be adsorbed on the electrode surfaces. Hence, the electrodes which are having high surface area can exhibit higher desalination capacity. In this article, the application of various carbon-based composite electrode materials such as activated carbon and PVDF composite, carbon–metal oxide composite, carbon–CNT composite, carbon–polymer composite and carbon sheet (carbon aerogel, activated carbon cloth) in CDI process is systematically reviewed and presented. CDI process is being developed now-a-days especially toward commercialization in treating the brackish water. 相似文献