Assessment of Groundwater Quality of the Central Gangetic Plain Area of India Using Geospatial and WQI Techniques     

Dharmendra Kumar Verma  Gouri Sankar Bhunia  Pravat Kumar Shit  Ashwani Kumar Tiwari 《Journal of the Geological Society of India》2018,91(6):743-748

The paper presents results of research to determine the health risk of potentially toxic elements (PTEs) in soils of gold mining area in Ilesha, Southwestern Nigeria. Eighteen top soil samples were collected and analysed for PTEs using ICPMS. The pollution level in soils were assessed using pollution load index (PLI) and potential ecological risk index (PERI). The human health risk was assessed using hazard index (HI), non-carcinogenic risk index and carcinogenic risk index. All the PTEs were higher than crustal average values except Fe and follow the order Mn > Ba > Cr > Zn > Cu > Ni > Pb > Co >Fe > As > Cd. The soil samples can be classified as unpolluted to moderately polluted (0.18-1.23) and low risk (15.28-94.24) based on PLI and PERI respectively. The values of hazard Index (HI) calculated for child and adult population for all the pathways were <1 and pose no obvious non carcinogenic risk to the population except for ingestion pathway where 33% of the samples showed value >1 in child population. As, Co, Cd and Pb constituted high cancer risk in the study area with child at higher risk than adult. The Total Cancer Risk (TCR) in the study area based on all the pathways ranges between 0.19 -3.86 and 0.18-3.58 for child and adult respectively and the ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway.  相似文献   

Hydrochemistry of groundwater of Thiruporur block, Tamil Nadu (India)     

Imran Ahmad Dar  K. Sankar  Syed Tanzeem Shafi  Mithas Ahmad Dar 《Arabian Journal of Geosciences》2012,5(2):259-262

An attempt has been made in this work to evaluate the environmental chemistry of groundwater in Thiruporur block, Kancheepuram District, Tamil Nadu, India. Eleven villages of Thiruporur block were selected; where the people use groundwater for drinking purpose, and the water samples were subjected to systematic analysis with a view to understand the potability of drinking water sources. The depth of the bore wells varied from 100 to 200?feet. The values obtained for different parameters were compared with the standard values given by ISI/ICMR/WHO and the variations were notable for the parameters like nitrate and total hardness for few samples. Therefore, a medical survey was carried out to study the harmful effects on the society due to these two parameters at the villages??Kayar and Melkottaiyar.  相似文献   

Spatial prediction of soil properties in a watershed scale through maximum likelihood approach     

Priyabrata Santra  Bhabani Sankar Das  Debashish Chakravarty 《Environmental Earth Sciences》2012,65(7):2051-2061

Surface map of soil properties plays an important role in various applications in a watershed. Ordinary kriging (OK) and regression kriging (RK) are conventionally used to prepare these surface maps but generally need large number of regularly girded soil samples. In this context, REML-EBLUP (REsidual Maximum Likelihood estimation of semivariogram parameters followed by Empirical Best Linear Unbiased Prediction) shown capable but not fully tested in a watershed scale. In this study, REML-EBLUP approach was applied to prepare surface maps of several soil properties in a hilly watershed of Eastern India and the performance was compared with conventionally used spatial interpolation methods: OK and RK. Evaluation of these three spatial interpolation methods through root-mean-squared residuals (RMSR) and mean squared deviation ratio (MSDR) showed better performance of REML-EBLUP over the other methods. Reduction in sample size through random selection of sampling points from full dataset also resulted in better performance of REML-EBLUP over OK and RK approach. The detailed investigation on effect of sample number on performance of spatial interpolation methods concluded that a minimum sampling density of 4/km² may successfully be adopted for spatial prediction of soil properties in a watershed scale using the REML-EBLUP approach.  相似文献   

The Flight Dynamics of Tapejara,a Pterosaur From the Early Cretaceous of Brazil with a Large Cranial Crest     

Sankar CHATTERJEE  and R. Jack TEMPLIN 《《地质学报》英文版》2012,86(6):1377-1388

Tapejara wellnhoferi, a small azhdarchoid pterodactyloid from the Early Cretaceous Santana Formation of Brazil, provides critical information about the aerodynamic function of its spectacular head crest. The cranial crests in pterodactyloids were sexually dimorphic and are thought to have evolved in adult males in response to female mate choice. However, the location of cranial crests in front of the center of gravity would create instability in the yaw axis during flight and may seem like a handicap. Vertically aligned webbed feet probably suppressed the yawing rotations and instability from the crest. Here we show that the crest functioned as a front rudder to make agile turn and mediate flight control. A computer simulation model suggests that Tapejara had a large excess of muscle power available above the power required for continuous flapping flight. It could easily takeoff from a perch, ground, or water surface and land safely on the ground. It was an excellent glider with a gliding angle close to 4o and a cruising speed of 27 km/h. Tapejara could soar efficiently on the windward side of cliffs or circle on rising thermals over tropical waters for efficient long-distance flight. Various control surfaces in the wings of Tapejara analogous to the slat, aileron, elevator, fin, rudder, and horizontal stabilizer of an aircraft made pterodactyloids versatile flyers.  相似文献   

Ground-motion predictions in Shillong region, northeast India   总被引：1，自引：0，他引：1  

Sankar Kumar Nath  Kiran Kumar Singh Thingbaijam  Soumya Kanti Maiti  Avinash Nayak 《Journal of Seismology》2012,16(3):475-488

We deliver ground-motion prediction equations for Shillong region, northeast India, based on a database generated by finite-fault stochastic simulations. An examination of the regional seismic source characteristics is carried out beforehand. Micro/minor earthquakes (M _W?<?5.0) nucleating at hypocentral depth <21?km in the region recorded at broadband seismic stations are observed to have Brune stress-drop ranging between 2.8 and 99.9?bars. Likewise, macroseismic intensity data for the 1897 Shillong Earthquake that nucleated at a hypocentral depth of ~35?km places the associated stress-drop at 100?200?bars. The apparent variation of the stress-drop parameter with depth is considered with two source zones namely lower-crust and upper-crust. Equations for the lower-crust predict higher ground-motion levels and exhibit affinity to those developed for stable continental region of Eastern North America. The ground-motion levels predicted by the equations for the upper-crust are relatively lower but are still higher compared with those predicted for tectonically active regions, viz., the Himalayas and Western North America.  相似文献   

Diversity and Distribution of Microzooplankton Tintinnid (Ciliata: Protozoa) in the Core Region of Indian Sundarban Wetland          下载免费PDF全文

Dibyendu Rakshit  Santosh K. Sarkar  Kamala K. Satpathy  Palani Sankar Ganesh  Nallamuthu Godhantaraman  Jayanta K. Biswas 《洁净——土壤、空气、水》2016,44(10):1278-1286

  相似文献   

A regularized Wiener–Hopf filter for inverting models with magnetic susceptibility          下载免费PDF全文

Shib Sankar Ganguli  Goutam Kumar Nayak  Nimisha Vedanti  V.P. Dimri 《Geophysical Prospecting》2016,64(2):456-468

For a magnetic target, the spatial magnetic signal can be expressed as a convolutional integral over Green's function of an assumed model with susceptibility as its parameter. A filter can be used to obtain the susceptibility by minimizing the mismatch between observed and the computed magnetic anomalies. In this perspective, we report the development of an advanced digital filter, which is efficient and can be used to map rock susceptibility from the acquired magnetic data. To design the new filter, we modified the space‐domain standard Wiener–Hopf filter by imposing two different constraints: (i) the filter energy constraint; and (ii) normalization of the filter coefficients. These constraints make it capable to characterize source bodies from their produced magnetic anomalies. We assume that the magnetic data are produced by induced magnetization only and interpretation can be as good as the subsurface model. Our technique is less sensitive to the data noise, which makes it efficient in enhancing the interpretation model. The modified filter demonstrates its applicability over the synthetic data with additive white Gaussian noise. In order to check the efficacy and adaptivity of this tool in a more realistic perspective, it is also tested on the real magnetic data acquired over a kimberlitic district adjoining to the western margin of the Cuddapah Basin in India to identify the source bodies from the anomalies. Our result shows that the modified Wiener–Hopf filter with the constraint for the magnetic data is more stable and efficient than the standard Wiener–Hopf filter.  相似文献   

Microtremor survey in Talchir, India to ascertain its basin characteristics in terms of predominant frequency by Nakamura's ratio technique   总被引：2，自引：0，他引：2  

M. Yanger Walling  William K. Mohanty  Sankar K. Nath  Supriyo Mitra  Ajesh John   《Engineering Geology》2009,106(3-4):123-132

The Talchir Basin, one of India's oldest basins, has been a subject of interest because of its rich coal deposits. The maximum thickness of the basin is about 1500 m. Beyond the basin is the hard metamorphic rocks of Precambrian age. The ambient noise survey data have been analyzed for the Talchir Basin using Nakamura's technique of horizontal–vertical-spectral-ratio (HVSR) to ascertain the basin structure in terms of the predominant frequency. The predominant frequency varies from 0.25 Hz to 7.8 Hz but a major portion of the basin comes under the range of 0.3 Hz–2.4 Hz while on the metamorphic rocks it is as high as 7.8 Hz. The variation in predominant frequency shows a good correlation with the sediment thickness of the basin. The results have been compared with the previous studies by other researchers and it shows consistency with the northerly dip of the basin. The present study has also been compared with the results of the synthetic seismogram that was performed for the Talchir Basin. The predominant frequency obtained from HVSR technique complements well with the frequency at which the peak response spectra ratio is observed. The present study of the predominant frequency identifies quite well the characteristics of Talchir Basin and is in good agreement with the synthetic ground motion modeling of the region.  相似文献   

Influence of enzymatic lime on clay mineral behavior     

Greeshma Nizy Eujine  Sreedharan Chandrakaran  Natesan Sankar 《Arabian Journal of Geosciences》2017,10(20):454

Atterberg Limit Tests, unconfined compressive strength tests, and California Bearing Ratio Tests were conducted on the two minerals—kaolinite and bentonite—after subjecting them to stabilization with lime, enzyme, and enzymatic lime. The purpose of the study was to evaluate the effectiveness of enzymatic lime as a stabilizer over lime and enzyme. Results establish that enzymatic lime stabilization is the better stabilizer in terms of strength development. The unconfined compressive strength and California Bearing Ratio values of enzymatic lime stabilized samples have increased up to 5 and 30 times in the case of kaolinite mineral, but to only less than 1.5 times in the case of bentonite mineral. The study thus indicates that enzymatic lime stabilization is predominantly effective for clays containing kaolinite minerals.  相似文献   

Transport and Biological Fate of Toluene in Low-Permeability Soils   总被引：1，自引：0，他引：1  

Sankar N. Venkatraman  David S. Kosson  John R. Schuring 《Ground Water Monitoring & Remediation》1998,18(1):105-113

The effect of simultaneous sorption, diffusion, and biodegradation on the fate and transport of toluene in low-permeability soil formations was examined. A transport model accounting for vapor and liquid sorption, vapor diffusions, and first-order biodegradation was developed to describe the movement of volatile solute in unsaturated soils. Modeling studies were followed with laboratory batch and column studies on fine-grained soil samples obtained from a gasoline-contaminated site. Batch experiments yielded the sorption and diffusion coefficients for generating theoretical solute transport profiles. Column studies were conducted to examine toluene sorption, diffusion, and biodegradation under aerobic and denitrifying conditions. Results from the column studies indicated that vapor sorption onto the soil was minimal due to the high moisture content of the soil. Comparison of model predictions with experimental results indicated that the SASK model, which is based on the resistivity theory, provided a more accurate prediction of the vapor phase tortuosity than the frequently used Millington-Quirk equation. Laboratory results of toluene concentration profiles matched well with the model predictions and yielded degradation rates comparable to those obtained in the field. Column studies, examining toluene biodegradation under aerobic and denitrifying conditions in low-permeability soils, indicated that the presence of excess nitrate in aerobic environments yielded higher solute degradation rates than those observed under exclusively aerobic systems.  相似文献