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991.
Pawan Govil Abhijit Mazumder Anoop Tiwari Sandeep Kumar 《Journal of the Geological Society of India》2011,78(1):30-35
A sediment core (L2) from Larsemann Hills, Antarctica was analyzed for Biogenic Silica (BSi), Sand (%) and Total Organic Carbon
(TOC). The 78 cm core length represents the time span of ∼8.3 cal ka BP. The values of BSi from the core show prominent high
productivity from ∼8.3 to ∼6 cal ka BP in comparison to less productivity in mid-late Holocene (∼6 cal ka BP to recent). Moreover,
high sand (%) infers the glacio-fluvial deposition from ∼8.3 to ∼5 cal ka BP TOC shows little variation through out the core,
except in the upper ∼10 cm (∼4 cal ka BP) part wherein it is comparatively high. The increased TOC in the upper part of the
core possibly indicates presence of algal mat due to exposure of the lake to the ice free (glacier free) conditions. 相似文献
992.
M. B. Verma P. S. Dandele G. Nagendra Babu K. Umamaheswar P. B. Maithani 《Journal of the Geological Society of India》2011,78(5):468-476
Relationship of hydro-uranium anomalies (2-649 ppb) vis-à-vis underlying uranium ore body has been attempted based on seventy nine water samples collected from the exploratory boreholes on the northern periphery of Srisailam sub basin, Nalgonda district, A.P. Water table is hosted in the granitoid aquifer which underlies the cover rocks of Srisailam Formation. TDS (total dissolved salt) range from 123 to 1088 ppm (x? = 329 ppm) and analyzed >500 ppm in eight samples. Water samples show a strong positive correlation of TDS with Cl? (r=0.90), Na+ (r=0.82), Mg (r=0.80) and a moderate positive correlation with Sr (r=0.48) and Ca (r=0.70). Low value (<0.4) of Normalised Magnesium (NMg) indicates that host rock aquifer has not undergone chloritisation. Accumulate contour plan of uranium ore body shows NW-SE trend and coincides with the hydro-uranium contour. Correlation sections of ore body display true as well as false hydro-uranium anomalies in N-S and E-W profiles. Hydro-uranium anomalies owe their origin to uranium cations, dissolved from the mineralized horizon in to groundwater. Hydro-geochemical orientation survey carried out at Chitrial plateau may be applied regionally in the Srisailam sub basin as an effective tool to explore the concealed unconformity type uranium mineralization below Srisailam Formation. 相似文献
993.
Sudhir Kumar Subrata Halder D. C. Singhal 《Journal of the Geological Society of India》2011,78(6):587-598
Groundwater utilization in Nadia district, West Bengal has been subjected to rapid exploitation in the wake of increasing
urbanization and production of agricultural commodities. It is, therefore, necessary to evaluate the existing trend and availability
of groundwater in time and space and its movement for proper planning in future. In the present study, an attempt has been
made develop a groundwater management model using Visual MODFLOW software. The groundwater flow model for the study area was
formulated by using input hydrogeological data and appropriate boundary conditions. The groundwater flow pattern of the study
area indicates the occurrence of base flow which feed both the Rivers Bhagirathi and Jalangi throughout the year. The computed hydraulic heads were calibrated by comparing with observed groundwater level data for years
2004 to 2006 and were verified with the data of 2007. The outcome of modeling shows that this model can be used for prediction
purpose in the future by updating input boundary conditions and hydrologic stresses during the preceding year. The model optimized
unit draft for deep tube well as 556.5 m3/day and the same for shallow tube well as 41 m3/day keeping the existing tube well structures in running condition and maintaining the present and recent past trends of
groundwater level. The model can be further improved if more spatial and temporal input parameters are available and can be
incorporated into the model for more realistic characterization of groundwater flow. 相似文献
994.
Chemical weathering of the Indo-Gangetic alluvium with special reference to release of fluoride in the groundwater,Unnao district,Uttar Pradesh 总被引:1,自引:0,他引:1
In the central part of Indo-Gangetic alluvium in the Unnao district, Uttar Pradesh there are many pockets where groundwater
shows high fluoride content. Drinking of fluorinated ground water has effected a large population and in many villages more
than 80% of the population is suffering from fluorosis. The source of this fluoride appears to be the alluvial sediments deposited
in the geological past as no hard rock terrain is present in the nearby areas. The area is dominantly made up of mud with
pockets of sand. The sand fraction is made up of quartz, plagioclase, microcline, muscovite and biotite along with some accessory
minerals like garnet, epidote, chlorite, tourmaline, hornblende, kyanite and a few opaque minerals. Moreover, the fluoride
content in the groundwater varies both spatially and with depth indicating a sporadic occurrence. The surface water is devoid
of high content of fluoride but is reported in hand pumps and in the dug wells. This paper deals with the geochemical study
of the sediments up to a depth of 45m as most of the hand pumps are up to this depth to understand the source of fluoride.
14C dates of calcretes have suggested that the 45 m thick succession must have been formed in about 45000 years. 相似文献
995.
N.?NatarajanEmail author G.?Suresh Kumar 《Geotechnical and Geological Engineering》2011,29(4):477-491
In this study, the behavior of thermal fronts along the fracture is studied in the presence of fracture-skin in a coupled
fracture-matrix system. Cold water is injected into the fracture, which advances gradually towards production well, while
extracting heat from the surrounding reservoir matrix. The heat conduction into the fracture-skin and the rock-matrix from
the high permeability fracture is assumed to be one dimensional perpendicular to the axis of fluid flow along the fracture.
Constant temperature cold water is injected through an injection well at the fracture inlet. The fluid flow takes place along
the horizontal fracture which ensures connectivity between the injection and production wells. Since the rock-matrix is assumed
to be tight, the permeability of fracture-skin as well as the rock-matrix is neglected. The present study focuses on the heat
flux transfer at the fracture-skin interface as against the earlier studies on fracture-matrix interface, and the sensitivity
of additional heterogeneity in the form of fracture skin in a conventional fracture-matrix coupled system is studied. The
behavior of thermal fronts for various thermal conductivity values of the fracture-skin and rock-matrix is analyzed. Spatial
moment analysis is performed on the thermal distribution profiles resulting from numerical studies in order to investigate
the impact on mobility and dispersion behavior of the fluid in the presence of fracture-skin. The presence of fracture skin
affects the heat transfer significantly in the coupled fracture-matrix system. The lower order spatial moments indicate that
the effective thermal velocity increases with increase in skin thermal conductivity and a significant thermal dispersion is
observed at the inlet of the fracture owing to the high thermal conductivity of the fracture-skin at the early stages. Furthermore
the higher spatial moments indicate that the asymmetricity increases with decrease in skin thermal conductivity unlike the
case with half fracture aperture and fluid velocity and the kurtosis is maximum with higher skin thermal conductivity which
implies enhanced heat extraction from the fracture-skin into the fracture. Results suggest that the amount of heat extraction
by the circulating fluid within the fracture from the reservoir not only depends on the rock-matrix module of the reservoir
characteristics but also the fracture-skin characteristics of the system and subsequently influence the reservoir efficiency. 相似文献
996.
Surendra P. Verma Rosalinda González‐Ramírez Rodolfo Rodríguez‐Ríos 《Geostandards and Geoanalytical Research》2011,35(2):183-192
Pressed powder pellets and fused beads or glass disks are routinely used in X‐ray fluorescence spectrometry for the determination of major and trace elements, respectively, in geological materials. In order to evaluate the performance of these two sample preparation methods, we determined Ni and Cr concentrations of fourteen RMs from Japan, France and South Africa, and eighty‐five igneous and three sedimentary rock samples from Mexico in both powder pellets and glass beads. We also computed new values of statistical parameters for RMs from an outlier‐based multiple‐test method and compared them with the literature mean and confidence limit values. The results showed that the multiple‐test method provided more reliable central tendency and dispersion parameters for RMs than those obtained previously from the two or three standard deviation method, or from robust methods. The powder pellet and fused bead sample preparation methods provided consistent results for Ni and Cr at concentration levels > 50 μg g?1 in this application; for lower concentration levels, however, these methods showed somewhat greater differences. For quantitative comparisons, both ordinary and weighted least‐squares linear regression models were used to show that the two sample preparation methods provided generally unbiased results. 相似文献
997.
M. Shakir Khan M. Zubair Deepak Verma A. H. Naqvi Ameer Azam M. K. Bhardwaj 《Environmental Earth Sciences》2011,63(2):279-282
Radon and its progeny have been recognized as one of the major contributors to the natural radiation and health hazards in
the human dwellings. Even lung cancer is expected if it is present in enhanced levels beyond maximum permissible limit. This
paper reports the measurements of indoor radon and its progeny in the urban dwellings of the Etah district of Uttar Pradesh
province in Northern India using the cellulose nitrate (LR-115 type-II) plastic track detectors. It is found that the values
of radon concentration vary from 3.52 to 248.64 Bq m−3 with a standard deviation of 69.19. The values of radon progeny concentration vary from 0.38 to 26.88 mWL with a standard
deviation of 7.48. The effective dose has been calculated and found to vary from 0.05 to 3.76 mSv year−1 with a standard deviation of 1.05. The lifetime fatality risk is found to vary from 0.04 × 10−4 to 2.90 × 10−4. The results have been compared with the results reported in the rural areas of the same district. 相似文献
998.
The role of biofilm proteins in modulating cyprid metamorphosis is not well understood. In the present investigation this possibility was explored by disrupting biofilm proteins using commercially available protease. The influence of natural biofilm and artificial biofilms of Aeromonas salmonicida salmonicida and Bacillus brevis and their culture supernatants and exopolysaccharides obtained under different nutritional conditions was evaluated. Natural biofilm facilitated cyprid metamorphosis in Balanus amphitrite, whereas monospecies biofilms did not. The treatment of biofilms with protease resulted in a decline in metamorphosis, except in B. brevis, where although metamorphosis was negated initially, it increased with the protease concentration and observation days. As the response of cyprids to exopolysaccharides produced by A. salmonicida salmonicida was dependent on protein concentration, protease treatment resulted in a decrease in metamorphosis, whereas in case of B. brevis biofilms, protease hydrolysis products could be important in providing settlement cues. Thus, biofilm bacterial components play an important role in the cyprid metamorphosis of Balanus amphitrite. 相似文献
999.
Rakhee Khandeparker Preeti Verma Ram M. Meena Deepti D. Deobagkar 《Estuarine, Coastal and Shelf Science》2011
Coastal and estuarine waters are highly productive and dynamic ecosystems. The complex carbohydrate composition of the ecosystem would lead to colonisation of microbial communities with abilities to produce an array of complex carbohydrate degrading enzymes. We have examined the abundance and phylogenetic diversity of culturable bacteria with abilities to produce complex carbohydrate degrading enzymes in the Mondovi and Zuari eustauri. It was interesting to note that 65% of isolated bacteria could produce complex carbohydrate degrading enzymes. A majority of these bacteria belonged to Bacillus genera followed by Vibrio, Marinobacter, Exiquinobacterium, Alteromonas, Enterobacter and Aeromonas. Most abundant bacterial genus to degrade hemicellulose and cellulose were Bacillus and Vibrio respectively. Most abundant bacterial genus to degrade hemicellulose and cellulose were Bacillus and Vibrio respectively. It was seen that 46% of Bacillus had ability to degrade both the substrate while only 14% of Vibrio had bifunctionality. 相似文献
1000.
Halder Debjani Kheroar Shyamal Srivastava Rajiv Kumar Panda Rabindra Kumar 《Theoretical and Applied Climatology》2020,140(3):823-838
Theoretical and Applied Climatology - Temperature and CO2 are the two most important climate parameters that affect crop yield directly. In this study, the impact of these two parameters on the... 相似文献