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91.
Narendra Kumar Meena M. Prakasam Ravi Bhushan Sudipta Sarkar Pranaya Diwate Upasana Banerji 《Environmental Earth Sciences》2017,76(1):39
The lakes of the Himalaya are degrading due to increase in toxic heavy metal loading. This study reports the last 50-year heavy metal pollution loading in the Rewalsar Lake, Himachal Pradesh, India. Sediment cores were recovered to study the pollution loading in the lake sediments. The 137Cs and 210Pb isotope-based sedimentation rate suggest rapid sedimentation in the lake during the last ~50 years. The concentrations of Mn, Cu, Zn, Cd, Pb, Co, Ni, Cr metals in the lake sediments owe its contributions both to the natural and anthropogenic sources. Prior to ca 1990 AD, metal loading was dominated by the lithogenic input, whereas post ca 1990 AD the metal loading was controlled by the anthropogenic factors. The Pb concentration in the lake gradually increased during 1990–2004 and then decreased significantly till present. The higher concentration of Pb seems to be derived from the fossil fuel burning, while the Cr concentration in the lake indicates the use of fertilizer in the catchment area. The lowest concentrations of elements around ca 1990 AD seem to have occurred due to channelization of the lake feeding system. 相似文献
92.
K. P. Singh G. C. Stewart N. J. Westergaard S. Bhattacharayya S. Chandra V. R. Chitnis G. C. Dewangan A. T. Kothare I. M. Mirza K. Mukerjee V. Navalkar H. Shah A. F. Abbey A. P. Beardmore S. Kotak N. Kamble S. Vishwakarama D. P. Pathare V. M. Risbud J. P. Koyande T. Stevenson C. Bicknell T. Crawford G. Hansford G. Peters J. Sykes P. Agarwal M. Sebastian A. Rajarajan G. Nagesh S. Narendra M. Ramesh R. Rai K. H. Navalgund K. S. Sarma R. Pandiyan K. Subbarao T. Gupta N. Thakkar A. K. Singh A. Bajpai 《Journal of Astrophysics and Astronomy》2017,38(2):29
The Soft X-ray focusing Telescope (SXT), India’s first X-ray telescope based on the principle of grazing incidence, was launched aboard the AstroSat and made operational on October 26, 2015. X-rays in the energy band of 0.3–8.0 keV are focussed on to a cooled charge coupled device thus providing medium resolution X-ray spectroscopy of cosmic X-ray sources of various types. It is the most sensitive X-ray instrument aboard the AstroSat. In its first year of operation, SXT has been used to observe objects ranging from active stars, compact binaries, supernova remnants, active galactic nuclei and clusters of galaxies in order to study its performance and quantify its characteriztics. Here, we present an overview of its design, mechanical hardware, electronics, data modes, observational constraints, pipeline processing and its in-orbit performance based on preliminary results from its characterization during the performance verification phase. 相似文献
93.
Pramod K. Rajak Vijay K. Singh Prakash K. Singh Asha Lata Singh Narendra Kumar Om Prakash Kumar Vishvajeet Singh Aniruddha Kumar 《Environmental Earth Sciences》2018,77(19):698
The Barmer Basin of Rajasthan is significant for its Paleogene lignite sequences. The lignite seam occurs in Akli Formation of Barmer Basin at the depth of 06–241 m. A total of 57 lignite samples were collected from the working faces of lignite mine and were subjected to proximate analysis (moisture, ash yield, volatile matter, and fixed carbon), ultimate analysis (carbon, hydrogen, nitrogen, oxygen and sulfur), elemental analysis (Fe, Ca, Mg, Cd, Mn, K, Na, Cu, Co, Ni, Cr, Zn, and Pb) and rock-eval pyrolysis for mineral carbon (MINC). Some elements like Cu, Cd, Co, Ni, Zn, Pb, Na, and K occur in high concentration, while Mg and Ca have their concentrations lower than World Clarke average. In addition, various minerals and functional groups present in the lignite samples were analyzed through X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy. The mineral (weight and atomic) percentage has also been analyzed through scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS). 相似文献
94.
K. N. Rao K. Narendra P. S. Latha 《Journal of the Indian Society of Remote Sensing》2010,38(2):255-267
Runoff is one of the important hydrologic variables used in most of the water resources applications. The Soil Conservation
Service-Curve Number (SCS-CN) method is adopted for the estimation of surface runoff in the Mehadrigedda watershed area, Visakhapatnam
district, India using multispectral remote sensing data, curve number approach and normal rainfall data. The main source of
water in the Mehadrigedda watershed area is by rain, most of it drains off and only a little percolates into ground. The weighted
curve number is determined based on antecedent moisture condition (AMC)-II with an integration of hydrologic soil groups (HSGs)
and land use/land cover LULC categories. An integrated approach is applied to delineate the land use/land cover information
as adopted from NRSA classification. The recording of daily rainfall data during the years 1997–2006 is collected from Indian
Meteorological Department (IMD) rainguage center at Kottavalasa. It is observed that the annual rainfall-runoff relationship
during 1997–2006, which is indicating that the overall increase in runoff with the rainfall of the watershed area. Integration
of remote sensing (RS) and geographical infomation system (GIS) techniques provide reliable, accurate and up-to-date information
on land and water resources. 相似文献
95.
城市扩张是反映经济增长的重要指标,但随意的城市扩张也带来了严重的社会经济问题、环境问题以及城市土地管理问题。在这个背景下,理解城市扩张的过程对于指导城市的可持续增长具有重要意义。本研究采用基于遥感影像的监督分类方法,分析了甘达基流域内的两个大城市—博卡拉和巴拉普尔1990–2018年的城市用地变化。结果表明:在过去的28年,博卡拉和巴拉普尔的城市面积分别显著扩张了300%和近500%。人口增长、城市基础设施和便利的生活方式引起周边地区向城市的人口迁移,是造成本研究区城市扩张的主要原因。除此之外,不断变化的城市定义和城市边界的扩张是造成城市快速扩张的关键因素。由于上述两个城市拥有高水平的商业活动以及现代化的设施,未来城市规模可能继续扩大。应当通过城市规划和政策减少随意的城市扩张,从而实现城市的可持续发展。 相似文献
96.
We have studied the Mukundpura CM2 meteorite for magnetic properties as a function of temperature and magnetic field, as well as its Mössbauer spectrum, at room and low temperatures (up to 5 K). We find that the high temperature paramagnetic phase is followed by two magnetic transitions: a weak transition near 125 K and a strong transition at 8 K. The weak (125 K) magnetic phase can be attributed to complex Fe2+–Fe3+ constituents present in the meteorite. The absence of the characteristic sextet corresponding to magnetite in Mossbauer spectrum indicates that this magnetic phase is not magnetite, which, if present, must be in insignificant amount. The 8 K magnetic ordering is superimposed with weak ferromagnetic ordering, showing spin‐glass transition. The Mössbauer spectrum taken at 5 K substantiates the observed spin‐glassy nature, as very large hyperfine field ~32 T is recorded, causing localized subordering leading to spin‐glass behavior. The Mössbauer spectra also confirm that iron is mainly present in serpentine‐group minerals, both in ferrous and ferric states. The complete serpentinization of basic silicates indicates aggressive hydrous alteration. These results show that the observed spin‐glass signature is a characteristic feature of the cronstedtite phase in CM meteorites. This feature is unique to carbonaceous CM chondrites and could be used for nondestructive, quick, and independent classification of this rare class of meteorites. Furthermore, the absence of olivine and the presence of cronstedtite in Mossbauer spectra show that the degree of aqueous alteration observed is the most severe in Mukundpura CM2 meteorite, as compared to many other CM2 meteorites. The degree of aqueous alteration in CM2 carbonaceous chondrites increases in the sequence: Paris, Murchison, Murray, Mighei, Nogoya, Cold Bokkeveld, and Mukundpura. 相似文献
97.
98.
99.
Investigations related to scientific deep drilling to study reservoir-triggered earthquakes at Koyna,India 总被引:1,自引:0,他引:1
Harsh Gupta N. Purnachandra Rao Sukanta Roy Kusumita Arora V. M. Tiwari Prasanta K. Patro H. V. S. Satyanarayana D. Shashidhar K. Mallika Vyasulu V. Akkiraju Deepjyoti Goswami Digant Vyas G. Ravi K. N. S. S. S. Srinivas M. Srihari S. Mishra C. P. Dubey D. Ch. V. Raju Ujjal Borah K. Chinna Reddy Narendra Babu Sunil Rohilla Upasana Dhar Mrinal Sen Y. J. Bhaskar Rao B. K. Bansal Shailesh Nayak 《International Journal of Earth Sciences》2015,104(6):1511-1522
100.
Narendra Kumar Gontia Kamlesh N. Tiwari 《Journal of the Indian Society of Remote Sensing》2011,39(1):27-37
Crop yield estimation has an important role on economy development and its accuracy and speed influence yield price and helps
in deciding the excess or deficit production conditions. The water productivity evaluates the irrigation command through water
use efficiency (WUE). Remote sensing (RS) and geographical information system (GIS) techniques were used for crop yield and
water productivity estimation of wheat crop (Triticum aestivum) grown in Tarafeni South Main Canal (TSMC) irrigation command of West Bengal State in India. One IRS P6 image and four wide field sensor (WiFS) images for different
months of winter season were used to determine the Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation
Index (SAVI) for area under wheat crop. The temporally and spatially distributed spectral growth profile and AREASUM of NDVI
(ANDVI) and SAVI (ASAVI) with time after sowing of wheat crop were developed and correlated with actual crop yield of wheat (Yact). The developed relationships between ASAVI and Yact resulted high correlation in comparison to that of ANDVI. Using the developed model the RS based wheat yield (YRS) predicted from ASAVI varied on entire TSMC irrigation command from 22.67 to 33.13 q ha−1 respectively, which gave an average yield of 26.50 q ha−1. The RS generated yield based water use efficiency (WUEYRS) for water supplied from canal of TSMC irrigation command was found to be 6.69 kg ha−1 mm−1. 相似文献