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81.
The river Narmada is a major source of fresh water for the highly populated areas, predominantly the rural populations in Madhya Pradesh (Central India) and Gujarat (Western India). Modernization and industrialization in these areas have become a matter of concern due to changing environment and increasing social activities that influence the quality of water directly or indirectly. This investigation was undertaken to evaluate the quality of water along the banks of the river Narmada at different sampling sites using physico-chemical and bacteriological methods. The samples collected were analyzed per standard method parameters and were measured in situ. The correlation matrix indicated strong mutual dependency between the measured parameters (P < 0.05). Principal components analysis of the data indicates that two components (PC1 and PC2) influence the water quality to the extent of 57.4, 64.5 and 61.0% during rainy, winter and summer seasons, respectively. The mean values of the physico-chemical parameters of the river water samples were consistently higher than the levels certified by the World Health Organization and other regulatory bodies as polluted water. The presence of coliform bacteria in the water samples warrants for proper measures to reduce the pollution at point sources and requires proper remediation strategies to combat contamination in the river water. 相似文献
82.
In this paper we present a new class of nonsingular solutions representing time dependent balls of perfect fluid with matter-radiation
in general relativity. The solution of the class is suitable for interior modeling of a quasar i.e. a massive radiating star.
The interior solution is matched with a zero pressure Vaidya metric. From this solution we constructed a quasar model by assuming
the life time of the quasar of ≈107 year. We obtained a mass of the quasar of ≈109 M
θ
, linear dimension ≈1017 km and a rate of emission L
∞≈1047 erg/s. 相似文献
83.
N. Juyal R.K. Pant N. Basavaiah R. Bhushan M. Jain N.K. Saini M.G. Yadava A.K. Singhvi 《Journal of Asian Earth Sciences》2009,34(3):437-449
Proglacial lake sediments at Goting in the Higher Central Himalaya were analyzed to reconstruct the summer monsoon variability during the Last Glacial to early Holocene. Sedimentary structures, high resolution mineral magnetic and geochemical data suggest that the lacustrine environment experienced fluctuating monsoonal conditions. Optically stimulated luminescence (OSL) dating indicates that the lake sedimentation occurred before 25 ka and continued after 13 ka. During this period, Goting basin witnessed moderate to strengthened monsoon conditions around 25 ka, 23.5 ka–22.5 ka, 22 ka–18 ka, 17 ka–16.5 ka and after14.5–13 ka. The Last Glacial phase ended with the deposition of outwash gravel dated at ~11 ka indicating glacial retreat and the onset of Holocene condition. Additionally, centennial scale fluctuations between 16.5 ka and 12.7 ka in the magnetic and geochemical data are seen.A close correspondence at the millennial scale between our data and that of continental and marine records from the Indian sub-continent suggests that Goting basin responded to periods of strengthened monsoon during the Last Glacial to early Holocene. We attribute the millennial scale monsoon variability to climatic instability in higher northern latitudes. However, centennial scale abrupt changes are attributed to the result of albedo changes on the Himalaya and Tibetan plateau. 相似文献
84.
85.
Summary 25 representative karstic and lateritic bauxite samples from Europe, Asia and Africa were studied by a JEOL-JXA-5 electron-probe X-ray microanalyser. The main directions of the investigation were: determination of the microtextures and the distribution of the main elements in bauxite (Al, Fe, Ti, Si). Conclusions on the genesis of the textural constitution and on bauxitization are given. Further possibilities of using the electron-probe in solving different problems connected with bauxites are enumerated.
With 30 Figures 相似文献
Bauxit-Untersuchungen mit der Elektronstrahl-Mikrosonde
Zusammenfassung Es wurden 25 typische Karst- und Lateritbauxite aus Europa, Asien und Afrika mit Hilfe einer JEOL-JXA-5 Elektronstrahl-Mikrosonde untersucht. Die Hauptrichtungen der Untersuchung waren die Bestimmung der Mikrostruktur und die Verteilung der Hauptelemente in den Bauxiten (Al, Fe, Ti, Si). Es wurden mehrere Schlüsse bezüglich der Entwicklung der Strukturelemente und der Bauxitbildung gezogen. Weitere Anwendungs-möglichkeiten zur Lösung verschiedener Bauxit-Probleme werden angegeben.
With 30 Figures 相似文献
86.
Dr. G. Pantó 《International Journal of Earth Sciences》1967,57(1):141-148
In the Tertiary history of the Pannonian massif — typical example of median masses — the most remarkable features are the considerable thinning out and the increase of accessibility of the crust. Diversities of its behaviour with respect to ascending selective (ionic) currents — which are considered as primary causes of volcanism — are manifest in the distribution and characteristics of igneous products: on the culmination area (core) of the mantle dome Neogene volcanism is represented exclusively by huge ash-flow blankets (in three cycles) totalling 15,000 cu. kms in volume, while famous volcanic mountains of the border area consist of andesitic explosion, effusion and shallow intrusion products of much less (5000 cu. kms) extension. The two distinct trends of composition and petrogenetic features are explained by different conditions of ascent of the igneous material: 1. diffuse and extremely slow rise combined with intense contaminations yields ash-flow outpourings of rhyolitic composition; 2. speedy issue along chimneys controlled by the border fractures of the median mass feed normal andesitic volcanism.
Zusammenfassung Das pannonische Massiv, ein typisches Beispiel für die Zwischenmassive, ist in seiner tertiären Entwicklung neben bedeutender Ausdünnung durch eine erhöhte Penetrierbarkeit der Kruste gekennzeichnet. Ihr verschiedenes Verhalten gegenüber emporsteigenden, selektiven ionischen Strömungen, die als Ursachen der vulkanischen Erscheinungen angenommen werden, kommt in der Verteilung und im Charakter der vulkanischen Produkte klar zum Audruck: das zentrale Kulminationsgebiet der Mantelwölbung wurde in drei Hauptzyklen von riesigen, rhyolithischen Ignimbritdecken überflutet (etwa 15 000 km3), an den Randpartien erhoben sich dagegen andesitische Vulkangebirge, bestehend aus explosiven, effusiven und seichtintrusiven Bildungen (etwa 5000 km3). Abweichungen der Zusammensetzung und Ausbildung werden mit Verschiedenheiten des Aufstiegs erklärt: 1. schwache Wegsamkeit, sehr langsames Emporsteigen, bis zur Oberfläche anhaltende Kontamination Rhyolith-Fluttuffe; 2. rascher Magmenaufstieg, durch Randbrüche gefördert normaler andesitischer Vulkanismus.
Résumé Dans l'évolution tertiaire du massif pannonien — exemple le plus typique des « median mass » — c'est l'atténuation considérable de la croûte et l'augmentation de sa pénétrabilité qui sont les traits les plus remarquables. La résistance différentielle de l'écorce contre les courants ascendants (ioniques) sélectifs sortants des sources infracrustales (auxquels l'initiation du volcanisme est attribuée) vient d'être exprimée tout à fait nettement dans la répartition et faciès des produits ignés: au sommet de la protubérance du manteau (partie centrale) le volcanisme néogène consiste essentiellement en épanchements immenses (à trois reprises) du tuf rhyolithique soudé (ignimbrite) ( 15.000 km3), tandis qu'aux bords ce sont des montagnes « andesitiques » édifiées de produits d'explosion, d'effusion et de ceux d'intrusions peu profondes ( 5.000 km3). Les différences de composition et des caractères pétrogénétiques sont expliquées par les manières différentes de la montée des matériaux ignés: 1. pénétrabilité diffuse, soulèvement extrêmement lent, contaminations s'avançant jusqu'à la surface épanchements ignimbritiques à composition rhyolithique; 2. montée plus rapide par conduits le long des fractures marginales volcanisme habituel andesitique.
. ( ) , , . (15000 3). .相似文献
87.
Bulletin of Volcanology - 相似文献
88.
In this paper, we examine whether till grain size affects the range and occurrence of micromorphological features associated with subglacial shear. Our till samples were collected from two glaciers in Iceland, and varied in texture from a coarse, sandy clast-rich till (Fjallsjökull) to a fine-grained silty-sandy till (Vestari-Hagafellsjökull). We found a wide range of deformational microstructures that included skelsepic plasmic fabric, intraclasts of pre-existing eroded bedrock (basalt) and weathered clay and ‘mini-shear zones’ between clasts. We classified our micromorphological data into three classes; rotational, intermediate and linear. In addition to these observations, we performed extensive microfabric analysis at different scales on all of our samples. We found that the coarse-grained till contained a greater number and variety of microstructures than the fine-grained till. In addition, the fine-grained till showed a distinct lack of rotational structures that we attribute to the lack of significantly sized clasts in the matrix. We argue that the varied texture of the coarse-grained till provides a greater degree of perturbation within the shearing layer and so more distinct microstructures form. In a more fine-grained till, shearing is more homogeneous since there are less perturbations in the matrix and this leads to a more singular kind of microstructure. Our observations suggest that subglacial shear occurs within a multi-layered patchwork of different grain sizes, competence and pore water pressures. It is these factors that are so crucial in determining the occurrence and type of microstructural evidence we see in subglacial tills. 相似文献
89.
90.