Geochemical processes regulating groundwater chemistry with special reference to nitrate and fluoride enrichment in Chhatarpur area, Madhya Pradesh, India   总被引：1，自引：1，他引：0  

Ram Avtar  Pankaj Kumar  Akhilesh Surjan  L. N. Gupta  Koel Roychowdhury 《Environmental Earth Sciences》2013,70(4):1699-1708

The present study focuses on the hydrogeochemical composition of groundwater in Chhatarpur area with special focus on nitrate and fluoride contamination, considering the fact that groundwater is the only major source of drinking water here. Carbonate and silicate mineral weathering followed by ground water–surface water interactions, ion exchange and anthropogenic activities are mainly responsible for high concentrations of cations and anions in the groundwater in the region. The average concentration of nitrate and fluoride found in 27 samples is 1.08 and 61.4 mg/L, respectively. Nitrate enrichment mainly occurs in areas occupied with intense fertilizer practice in agricultural fields. Since the area is not dominated by industrialization, the possibility of anthropogenic input of fluoride is almost negligible, thus the enrichment of fluoride in groundwater is only possible due to rock–water interaction. The highly alkaline conditions, which favor the fluorite dissolution, are the main process responsible for high concentration of fluoride.  相似文献   

Response to comment by Keith Beven on “Equifinality of formal (DREAM) and informal (GLUE) Bayesian approaches in hydrologic modeling?”     

Jasper A. Vrugt  Cajo J. F. ter Braak  Hoshin V. Gupta  Bruce A. Robinson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(7):1061-1062

In recent years, a strong debate has emerged in the hydrologic literature regarding what constitutes an appropriate framework for uncertainty estimation. Particularly, there is strong disagreement whether an uncertainty framework should have its roots within a proper statistical (Bayesian) context, or whether such a framework should be based on a different philosophy and implement informal measures and weaker inference to summarize parameter and predictive distributions. In this paper, we compare a formal Bayesian approach using Markov Chain Monte Carlo (MCMC) with generalized likelihood uncertainty estimation (GLUE) for assessing uncertainty in conceptual watershed modeling. Our formal Bayesian approach is implemented using the recently developed differential evolution adaptive metropolis (DREAM) MCMC scheme with a likelihood function that explicitly considers model structural, input and parameter uncertainty. Our results demonstrate that DREAM and GLUE can generate very similar estimates of total streamflow uncertainty. This suggests that formal and informal Bayesian approaches have more common ground than the hydrologic literature and ongoing debate might suggest. The main advantage of formal approaches is, however, that they attempt to disentangle the effect of forcing, parameter and model structural error on total predictive uncertainty. This is key to improving hydrologic theory and to better understand and predict the flow of water through catchments.  相似文献   

Guest editorial     

Harsh Gupta  N. Purnachandra Rao  Robert Yeats 《Journal of Seismology》2009,13(3):313-314

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Implications of fault array evolution for synrift depocentre development: insights from a numerical fault growth model   总被引：7，自引：1，他引：6  

P. A. Cowie  S. Gupta  & N. H. Dawers 《Basin Research》2000,12(3-4):241-261

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Io/U ages of corals from Saurashtra coast: A reply     

S.K. Gupta  B.S. Amin 《Marine Geology》1975,19(4):276

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Utilisation of integrated remote sensing technique for coastal geomorphic and geologic data extraction—A case study for Coondapur,south Kanara district (Karnataka)     

P. K. Gupta 《Journal of the Indian Society of Remote Sensing》1988,16(1):41-46

Coastal zone is associated with several geomorphic features of erosional and depositional nature, be sides the broad geologic information. The area around Coondapur of south Kanara district, Karnataka, possesses all the major characteristics of coastal zone and these are extractable through intergated remotely sensed data namely Landsat-1 MSS imagery, Salyut-7 KATE space photograph and aerial photographs. The visual interpretation is carried out with developing remote sensing keys to decipher major geomorphic-geologic information like: spit, double spit, beach deposit, alluvium, levee deposit, la|terite and other rock types. It is concluded that the major geomorphic-geologic characteristics as well as subdeltaic drainage, soil erosoin are obtained through space borne data. The aerial photographs provide the detailed geomorphic and geologic information.  相似文献   

Spectroscopic diagnostics for N III ion     

B. N. Dwivedi  Anita Mohan  A. K. Gupta 《Astrophysics and Space Science》1996,243(1):163-163

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Exact solution of the transport equation in finite media with a plane and uniform point source and flux normally incident at the faces from outside     

S. Bishnu  S. R. Das Gupta 《Astrophysics and Space Science》1991,176(2):217-262

In this paper we apply the Wiener-Hopf technique combined with the method of the Laplace transform, to derive an exact solution of the transport equation for neutron diffusion in an isotropically scattering plane-parallel medium of finite thickness in which are situated a plane source at the middle and a uniformly distributed point source, there being flux of beams normally incident from outside on the two extreme parallel surfaces of the medium.  相似文献   

Timing and mechanisms of Central Himalayan exhumation: discriminating between tectonic and erosion processes     

Ana-Voica Bojar  Harald Fritz  Stefan Nicolescu  Martin Bregar  Ravi P. Gupta 《地学学报》2005,17(5):427-433

The ability to deduce exhumation mechanisms from thermochronological data is hampered by the fact that assumptions on the thermal state of the lithosphere have to be made. Additional argumentation is generally required to discriminate between erosion-controlled and tectonically induced exhumation. This problem can be overcome by studying the spatial distribution of zircon and apatite (U-Th)/He and fission track data. In this work the variation of four different low temperature isotopic systems generating age trends along a sampling line is used to infer mechanisms of Quaternary exhumation in the Central High Himalayan Metamorphic Belt. Observed zircon age trends with southwards increasing cooling ages (from 0.5 to 1.7 Ma) are attributed to tectonically induced exhumation. The uniform apatite cooling ages clustered c. 0.5 Ma are attributed to erosion.  相似文献   

A design study of atmospheric Cerenkov radiation telescope for very high energy gamma-ray astronomy     

S. K. Gupta  P. V. Ramana Murthy  S. C. Tonwar  P. R. Vishwanath 《Astrophysics and Space Science》1985,115(1):163-183

Detection of cosmic sources of very high energy gamma rays based on the atmospheric Cerenkov technique is discussed. Very high energy gamma-rays initiate, on entering the terrestrial atmosphere, electron-photon cascade showers with in turn produce Cerenkov photons in the air. Parabolic reflectors are used to focus these photons onto fast photomultipliers. Two methods of deployment of parabolic reflectors are in vogue: one in which all the reflectors are located close to each other in a compact array and the other in which the reflectors are spread out farther apart forming a distributed array. In the latter mode, the arrival direction of individual showers can be determined accurately by using the measured relative arrival times between different detectors. Detailed studies with the distributed array helped us to understand the various parameters in the two designs and evaluate their relative merits in reaching the ultimate goals of lowering the energy threshold and improving the signal to background ratio for the detection of gamma-ray sources. It is found that the relative superiority among the two types of arrays is a function of the exponent assumed for the differential power law energy spectrum for the gamma ray source. It is also seen that with the type of reflectors commonly used in atmospheric Cerenkov work, lower energy thresholds can be achieved with use of larger aperture.  相似文献