排序方式: 共有16条查询结果,搜索用时 0 毫秒
11.
12.
Riad A. Higazy 《Geochimica et cosmochimica acta》1952,2(3):170-184
The epidioritc and quartzite of the Malin Head district, (Ireland) are considered by Holmes and Reynolds [7] to be metasomatically transformed into skarn-rocks and mica-schist respectively. The trace element contents of these rocks were investigated using semi-quantitative methods in order to study the behaviour of the different trace elements during the metasomatic changes which have taken place. The elements which have been determined are Rb, Ba, Ag and Pb; Sr, Y and La; Li, Cr, Ni, Co, V, Cu, Sc, Sn and Mo; Ga; Zr, Be, Tl, Ge and In. The trace elements follow the major elements for which they can substitute in favourable crystal lattices, the substitution being in accord with Goldschmidts rules. Rb, Ba and probably Pb and Ag follow and substitute for K; Sr and Y for Ca and probably K; Li, Cr, Ni, Co, V, Cu, Sc, Sn and Mo for Mg, Fe2 and Fe3; and Ga for Al. 相似文献
13.
A model of rainfall–runoff relationships is an essential tool in the process of evaluation of water resources projects. In this paper, we applied an artificial neural network (ANN) based model for flow prediction using the data for a catchment in a semi‐arid region in Morocco. Use of this method for non‐linear modelling has been demonstrated in several scientific fields such as biology, geology, chemistry and physics. The performance of the developed neural network‐based model was compared against multiple linear regression‐based model using the same observed data. It was found that the neural network model consistently gives superior predictions. Based on the results of this study, artificial neural network modelling appears to be a promising technique for the prediction of flow for catchments in semi‐arid regions. Accordingly, the neural network method can be applied to various hydrological systems where other models may be inappropriate. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
K. Assami R. Ladji Y. Moussaoui N. Yassaa B. Y. Meklati 《International Journal of Environmental Science and Technology》2018,15(5):1019-1028
This work was carried out in order to study the impact of car body repair activities in Bouzaréah City (suburban area located at the plateau of Algiers) on the air quality. Atmospheric particulate matter was targeted using high-volume sampler. Precisely, the particulate organic matter such as organophosphate esters, especially triphenyl phosphate and tributyl phosphate, was evaluated by the implementation of accelerated solvent extraction. The results of the major extractable organic components revealed that tributyl phosphate and triphenyl phosphate were found at 5.46 and 1.78 ng m?3, respectively. On the other hand, the classical pollutants such as n-alkanes, n-alkanoic monocarboxylic acids and polycyclic aromatic hydrocarbons were also measured, respectively, at average total concentrations of 35.8, 107.4 and 9.8 ng m?3. This work confirms that sanding and painting car bodies may contribute to air pollution, especially after detection of diethylnitrosamine which remains the most surprising compound in the particulate matter due to its volatility and can be considered as emerging contaminant. 相似文献
15.
Numerical modeling of groundwater resource management options in the East Oweinat area,SW Egypt 总被引:1,自引:0,他引:1
A.?M.?EbraheemEmail author H.?K.?Garamoon S.?Riad P.?Wycisk A.?M.?Seif El Nasr 《Environmental Geology》2003,44(4):433-447
Southwest Egypt is an arid area with no surface water and limited resources of useable groundwater in the well-known Nubian Sandstone Aquifer System. These groundwater reserves have been heavily exploited since the 1960s, which has led to substantial decline in the potentiometric surface of the aquifer. A calibrated regional numerical model with refined grids on the pumping centers has been used to investigate the hydrodynamic impacts of different groundwater management options on the potentiometry of the aquifers. The results indicate that there is a real danger of either dewatering the shallow aquifer in some areas (e.g., Kharga Oasis), or increasing the water depth to uneconomic lifting depth. They also indicate that, although the planned extraction rates in Dakhla, Farafra, and Bahariya oases are feasible for at least the coming 100 years, the present rate for Kharga Oasis and the planned rate for the East Oweinat area have to be reduced substantially. 相似文献
16.
Eduardo Salamuni Hans Dirk Ebert Mauricio da Silva Borges Yociteru Hasui Joo Batista Sena Costa Riad Salamuni 《Journal of South American Earth Sciences》2003,15(8):901-910
The Curitiba Basin, Paraná, lies parallel to the west side of the Serra do Mar range and is part of a continental rift near the Atlantic coast of southeastern Brazil. It bears unconsolidated and poorly consolidated sediments divided in two formations: the lower Guabirotuba Formation and the overlying Tinguis Formation, both developed over Precambrian basement. Field observations, water well drill cores, and interpretations of satellite images lead to the inference that regional tectonic processes were responsible for the origin of the Basin in the continental rift context and for morphotecatonic evolution through block tilting, dissection, and erosion. The structural framework of the sediments and the basement is characterized by NE–SW-trending normal faults (extensional tectonic D1 event) reactivated by NE–SW-trending strike–slip and reverse oblique faults (younger transtensional tectonic D2′ to transpressional tectonic D2″ event). This tectonic event, which started in the Paleogene and controlled the basin geometry, began as a halfgraben and was later reactivated as a pull-apart basin. D2 is a neotectonic event that controls the current morphostructures. The Basin is connected to the structural rearrangement of the South American platform, which underwent a generalized extensional or trantensional process and, in late Oligocene, changed to a compressional to transpressional regime. 相似文献