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91.
P. Purushothaman M. Someshwar Rao Y. S. Rawat C. P. Kumar Gopal Krishan T. Parveen 《Environmental Earth Sciences》2014,72(3):693-706
Agricultural activities act as dominant polluter of groundwater due to increased fertilizers and pesticides usage. Bist-Doab region, Punjab, India, is one such region facing deterioration of groundwater quality due to usage of fertilizers. This study aims in delineating and evaluating the groundwater quality in the region. Water samples are collected from canals, reservoir, and shallow and deep groundwater. Water types in canal and reservoir in Kandi region are Mg2+HCO3 ? and Mg2+Ca2+Na+HCO3 ?, respectively. While water types of shallow and deep groundwaters are found to be of two types: Na+Mg2+Ca2+HCO3 ? and Ca2+Mg2+Na+HCO3 ?. Presence of Mg2+ in groundwater at locations adjoining canals indicates recharge due to canal. The major ion (Na+, Mg2+, Ca2+, HCO3 ?) chemistry of the region is due to weathering of rocks that are rich in sodic minerals and kankar. Deep groundwater quality in the region meets BIS and WHO standards for drinking purpose, unlike shallow groundwater which is of poor quality at many locations. Both shallow and deep groundwater with high sodium concentration (>1.5 meq/l) affect cropping yield and permeability of soil matrix. High concentration of SO4 2? and NO3 2? (>1 meq/l) in shallow groundwater at few locations indicates influence of anthropogenic (fertilizer) activity. Factor analysis indicates that the major cations, bicarbonate and chloride are derived from weathering/dissolution of source rocks. Higher concentration of nitrate and presence of sulphate in shallow groundwater at few locations is due to usage of fertilizers and pesticides. 相似文献
92.
Twenty private wells and ten stream locations were sampled to assess the source and fate of dissolved nitrate in the Cedar
River watershed of Iowa, USA. The average levels of nitrate in groundwater decreased from 39.5 mg/L in May, to 38 mg/L in
July, to 30 mg/L in September. Although several surface water samples exceeded MCL in May, most values dropped to below 20 mg/L
by July and September. The decreasing N levels were attributed to the gradual uptake of nitrate by growing crops as well as
the cyanobacterial growth in the aquatic systems. The δ15N values of dissolved nitrate in groundwater ranged from +0.45 to +5.35‰, whereas those in surface water ranged from +1.48
to +5.16‰. The results suggested that commercial fertilizers and soil organic nitrogen were probably mixed up in their transport
pathways. A fertilizer-only source would provide much lower delta values, whereas soil nitrogen would provide higher than
observed delta values. Denitrification was considered unlikely because of the low δ15N values, high nitrate concentrations, and moderately high DO content in groundwater. Animal wastes were not found as a possible
source of nitrate in the water. This is supported by the low chloride concentrations and lower than 10‰ delta values in the
water samples. The study demonstrates that nitrogen isotope data in coordination with the dissolved nitrate levels and land
use can be effectively used in nitrogen source identification and its transformation studies. 相似文献
93.
Anomalous land surface temperature and outgoing long-wave radiation observations prior to earthquakes in India and Romania 总被引:2,自引:1,他引:1
Vineeta Rawat Arun K. Saraf Josodhir Das Kanika Sharma Yazdana Shujat 《Natural Hazards》2011,59(1):33-46
Cumulative stress energy in an earthquake preparation zone under operating tectonic force manifests various observable signs
of the impending earthquake, i.e., earthquake precursors. This energy transformation may result in enhanced transient thermal
infrared (TIR) emission, which can be detected through satellites equipped with thermal sensors like AVHRR (NOAA), MODIS (Terra/Aqua).
This paper presents observations made using NOAA-AVHRR data–derived land surface temperature (LST) and outgoing long-wave
radiation (OLR) values in case of two moderate earthquakes (22 July 2007, Yamnotri earthquake, India and 27 October 2004,
Vrancea earthquake, Romania) using anomalous TIR signals as reflected in LST rise and high OLR values can be seen conspicuously
and following similar growth pattern spatially and temporally. In both the cases, data analysis revealed a transient thermal
infrared rise in LST ranging 5–10°C around epicentral areas. The thermal anomalies started developing about 7–8 days prior
to the main event depending upon the magnitude and focal depth and disappeared after the main shock. Similarly, the OLR values
~30–45 W/m2 higher than the normal were observed 7–8 days prior to the main event. The rise in LST can be attributed to enhanced greenhouse
gas emission from the squeezed rock pore spaces and/or to the activation of p-holes in stressed rock volume and their further
recombination at rock-air interface. OLR is temperature and humidity dependent, and any change in these variables may be responsible
for anomalous OLR values. 相似文献
94.
Net primary productivity and species diversity of herbaceous vegetation of banj-oak (Quercus leucotrichophora A.Camus) forest in Kumaun Himalaya,India were analyzed.Across different growth forms (tall forbs,short forbs,cushion and spreading forbs,grasses),short forbs were most dominant component during rainy season (IVI=152) and winter season (IVI=167) and grasses during the winter season (IVI=148).Maximum above-ground production occurred during rainy season (132.5 g m-2) and minimum during winter season (2.8 g m-2).Below-ground production was maximum (85.9 g m-2) during winter season and minimum (14.9 g m-2) during summer season.Annual net shoot production was 150 g m-2 and below-ground production was 138 g m-2.Of the total input 61 % was channeled to above-ground parts and 39% to below-ground parts. 相似文献
95.
J. D. Das Yazdana Shujat A. K. Saraf V. Rawat K. Sharma 《Journal of the Indian Society of Remote Sensing》2011,39(1):73-81
Present topography of Bhuban Hills, lying in the Indo-Burman frontal fold belt of Northeastern part of India, is an aberration
from a normal anticlinal morphology and exhibits several transverse and longitudinal fault affected segments resulting into
distinct morphotectonic units. Six different morphotectonic units could be delineated along N-S stretch of the hill ridge.
The western side of the northern most part of the hill ridge forms steep escarpment as this portion has been affected by the
longitudinal faulting representing a case of fault propagation folding. The northernmost segment comprising three morphotectonic
units (MU1 to MU3) is unique in the sense that this part exhibits effect of both the longitudinal and transverse faulting,
uplifted narrow ridge with downthrown eastern side (MU2). Northern part of the Bhuban Hills has become curved westward due
to the right lateral movement along the transverse fault TF1. The fifth morphotectonic unit (MU5) has undergone subsidence
whereas, the sixth unit (MU6) exhibit bulging effect as this part experienced differential fault movements. Stream profiles,
longitudinal and transverse topographic profiles extracted from contour map and Digital Elevation Model corroborated with
the topographical anomalies developed over the Bhuban Hills. 相似文献
96.
The present paper evaluates the temporal and spatial impact of heavy metal containing (Cr, Zn, Cu, Ni, Cd and Fe) effluents of brass, electroplating and tannery industries on chemical and microbiological characteristics of affected soil and groundwater. Therefore, samples were drawn from three sites, S1, S2 and S3, with a longitudinally distant from effluent drain of 20, 200 and 700 m, respectively. In general, the metals concentration exceeded the standard limits not only in the discharged effluents but also in the soil and groundwater. The significant reduction of microbial biomass C and N, soil respiration and microbial coefficient with increasing metal content from S3 to S1 was recorded, the effect being more pronounced in summer. However, the Cmic/Nmic ratio decreased whilst the metabolic quotient ($q_{{\rm CO}_{{\rm 2}} } $ ) increased with increasing metal concentration in soil. The content of Zn (11.5 mg/L) and Bacillus sp. was at maximum in groundwater of brass and electroplating industry site, whereas that of tannery site contained maximum Cr (2.34 mg/L) and Enterobacter sp. The toxic metals adversely polluted the groundwater which made it to harbours Escherichia coli beyond the prescribed limit. To check the soil and groundwater pollution, eco‐friendly measures involving improved effluent treatment technology and site‐specific application of treated effluent are recommended. 相似文献
97.
Sankar Narayan Patra Gautam Bhattacharya Koushik Ghosh Probhas Raychaudhuri 《Astrophysics and Space Science》2009,324(1):47-53
The solar irradiance data plays a very important role for understanding of Solar internal Structure and the solar terrestrial
relationships. The Total Solar Irradiance (TSI) is integrated solar energy flux over the entire spectrum which arrives at
the top of the atmosphere at the mean sun earth distance. TSI has been monitored from several satellites, e.g. Nimbus 7, Solar
Maximum Mission (SMM), The NASA, Earth Radiation Budget Satellite (ERBS), NOAA9, NOAA10, Eureca and the Upper Atmospheric
Research Satellite (UARS) etc. From these observations it reveals that the total solar irradiance varies about a small fraction
of 0.1 over solar cycle being higher during maximum solar activity condition. In the present paper we have analysed the solar
irradiance data from ERBS during the time period from October 15, 1984 to October 15, 2003. First filtering the data by Simple
Exponential Smoothing we have applied the Rayleigh Power Spectrum Analysis on the processed data in order to search for its
time variation. Study exhibits multi-periodicities on these data around 7, 11, 42, 80, 104, 130, 160, 254, 536, 752, 1142,
1388, 2474 and 4951 days with very high confidence levels (more than 95%). Apart from these strong periods there are some
other weak periods around 22, 47, 53, 67, 69, 149, 167, 365, 489 and 683 days. These periods are significantly similar with
the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities. 相似文献
98.
Neelam Chauhan A. K. Pandey K. Ogura D. K. Ojha B. C. Bhatt S. K. Ghosh P. S. Rawat 《Monthly notices of the Royal Astronomical Society》2009,396(2):964-983
The aim of this paper is to quantitatively testify the ' small-scale sequential star formation ' hypothesis in and around bright-rimmed clouds (BRCs). As a continuation of the recent attempt by Ogura et al., we have carried out BVIc photometry of four more BRC aggregates along with deeper re-observations of two previously observed BRCs. Again, quantitative age gradients are found in almost all the BRCs studied in the present work. Archival Spitzer /Infrared Array Camera data also support this result. The global distribution of near-infrared excess stars in each H ii region studied here clearly shows evidence that a series of radiation-driven implosion processes proceeded in the past from near the central O star(s) towards the peripheries of the H ii region. We found that in general weak-line T-Tauri stars (WTTSs) are somewhat older than classical T-Tauri stars (CTTSs). Also the fraction of CTTSs among the T-Tauri stars (TTSs) associated with the BRCs is found to decrease with age. These facts are in accordance with the recent conclusion by Bertout, Siess & Cabrit that CTTSs evolve into WTTSs. It seems that in general the equivalent width of Hα emission in TTSs associated with the BRCs decreases with age. The mass function (MF) of the aggregates associated with the BRCs of the morphological type 'A' seems to follow that found in young open clusters, whereas 'B/C'-type BRCs show significantly steeper MF. 相似文献
99.
Sr–Nd isotope data are reported for the early Precambrian sub-alkaline mafic igneous rocks of the southern Bastar craton, central India. These mafic rocks are mostly dykes but there are a few volcanic exposures. Field relationships together with the petrological and geochemical characteristics of these mafic dykes divide them into two groups; Meso-Neoarchaean sub-alkaline mafic dykes (BD1) and Paleoproterozoic (1.88 Ga) sub-alkaline mafic dykes (BD2). The mafic volcanics are Neoarchaean in age and have very close geochemical relationships with the BD1 type. The two groups have distinctly different concentrations of high-field strength (HFSE) and rare earth elements (REE). The BD2 dykes have higher concentrations of HFSE and REE than the BD1 dykes and associated volcanics and both groups have very distinctive petrogenetic histories. These rocks display a limited range of initial 143Nd/144Nd but a wide range of apparent initial 87Sr/86Sr. Initial 143Nd/144Nd values in the BD1 dykes and associated volcanics vary between 0.509149 and 0.509466 and in the BD2 dykes the variation is between 0.510303 and 0.510511. All samples have positive ? Nd values; the BD1 dykes and associated volcanics have ? Nd values between +0.3 and +6.5 and the BD2 dykes between +1.9 to +6.0. Trace element and Nd isotope data do not suggest severe crustal contamination during the emplacement of the studied rocks. The positive ? Nd values suggest their derivation from a depleted mantle source. Overlapping positive ? Nd values suggest that a similar mantle source tapped by variable melt fractions at different times was responsible for the genesis of BD1 (and associated volcanics) and BD2 mafic dykes. The Rb–Sr system is susceptible to alteration and resetting during post-magmatic alteration and metamorphism. Many of the samples studied have anomalous apparent initial 87Sr/86Sr suggesting post-magmatic changes of the Rb–Sr system which severely restricts the use of Rb–Sr for petrogenetic interpretation. 相似文献
100.
N. C. Gautam 《Journal of the Indian Society of Remote Sensing》1979,7(1):41-47
In this paper house density has been calculated on medium scale photographs and efforts have been made to recognize the physical characteristics of houses on aerial photographs for the purpose of house density mapping. Although the aerial photographs reveal wealth of information regarding the houses, only the residential plots as house units have been taken into account for the present study. 相似文献