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141.
U. C. Kulshrestha A. Saxena N. Kumar K. M. Kumari S. S. Srivastava 《Journal of Atmospheric Chemistry》1998,29(2):109-118
Size-differentiated concentrations of SPM, F, Cl, NO3, SO4, Na, K, Ca, Mg and NH4 in atmospheric aerosols were measured in a suburban area of Agra city during December 1992 to March 1993. Except for NH4, Cl and Na, all components were found to have a bimodal distribution. The fine fraction was dominated by NH4, K, NO3 and SO4, while Na, Ca, Mg, F and Cl contributed to the coarse fraction. Fifty-eight percent of SO4 and 67% of NO3 were found in the fine mode and the coarse mode comprised 42 and 33% of SO4 and NO3, respectively. SO4 was found to have a peak above the submicron range at 1.1 µm which has been attributed to secondary sulphate formation by heterogeneous oxidation of SO2 on alkaline particles of Ca and Mg. The total aerosol was basic in nature and dominated by the soil-derived acid neutralising components (Ca, Mg and Na). 相似文献
142.
Appraisal of highly fluoride zones in groundwater of Kurmapalli watershed,Nalgonda district,Andhra Pradesh (India) 总被引:2,自引:0,他引:2
N. C. Mondal R. K. Prasad V. K. Saxena Y. Singh V. S. Singh 《Environmental Earth Sciences》2009,59(1):63-73
Fluoride (F) contamination study had been carried out to see its allocation in Kurmapalli watershed, Nalgonda district, Andhra
Pradesh, India. The study area is located about 60 km SE of Hyderabad city. The groundwater is the main source of water for
their living. The groundwater in villages and its surrounding are affected by fluoride contamination and consequently the
majority of the people living in these villages has health hazards and is facing fluorosis. The purpose of this study is to
identify the wells with high F, raise awareness in people, study the water chemistry, and also find out the source of F in
groundwater. A total of 32 groundwater samples were collected from different wells in both shallow aquifers and deeper fractures
zones during October 2004. The chemical analysis of groundwater has been done. Fluoride values vary from 0.7 to 19.0 mg/l.
It is noted that the maximum value (19.0 mg/l) is one of the highest values found in groundwater in India and 78% of the total
samples show F concentrations that exceeds the permissible limit value (1.5 mg/l). The highest value of F is found at Madanapur
bore well which is located at central part of the watershed. The F value of this bore well was monitored from October 2004
to October 2006. During this period the F concentration varies from 17.8 to 21.0 mg/l with mean 19.3 mg/l. There is no correlation
of F with chemical parameters except calcium. The Ca has shown inverse proportional with F. Water–rock interaction studies
were also carried out to understand the behavior of F in groundwater at prominent F affected areas. Rock samples were collected
and analyzed, and found their enrichment of F. The anthropogenic possibility of F is almost negligible. The rocks of this
area are enriched in F from 460 to 1,706 mg/kg. It is indicated that the rock–water interaction is the main source of F in
groundwater. The highest values of F are found in middle part of the region and are related to the occurrence of fluoride
rich rocks and their chemical kinetic behavior with groundwater. 相似文献
143.
A combined boundary-element–finite-element method is presented for the analysis of distresses in pavements subjected to mechanical and environmental effects. Owing to the spatial dimensions of the problem, the non-homogeneity and the irregular geometry at the pavement joints, a combination of the two methods proves to offer a more realistic solution technique. The advantage of the finite element method (FEM) is in its capabilities of modelling near-field regions at or around the vicinity of the joint, whereas the boundary element method (BEM) is more suitable to model the far-field region at infinity. The three major distresses affecting the serviceability of the pavement system are the temperature, moisture and the applied mechanical loads. The model analyses the stresses and strains resulting from both mechanical and environmental factors in the analysis of a pavement system. Moreover, the infiltration of water through pavement joints, which causes weakening of the subgrade soil, is also analysed. Secondly the curling of the pavement concrete slab under the mechanical and thermal loads and induced friction may cause separation of the pavement structure from its supporting subgrade. Both are treated and modelled in this study. A detailed analysis of the pavement joint with its load transfer device is also performed for the proper assessment of the separation and further extension of the loss of support in the pavement system. 相似文献
144.
For the delineation of water-bearing fractures in hard rock areas, a new hydro-chemical technique has been developed which
is based on electrical conductivity (EC) logs. The EC logs were carried out in experimental shallow bore wells (≈50 m) in
three different parts of India. A sharp variation in EC was observed near water-bearing fractures in hard rock areas. To access
applications of this technique, different locations in India were selected and experimental bore wells (≈50 m) were drilled.
These were:
Observations on EC logs were made at short intervals of 1.0 m from the water table (narrow spacing wherever required) until
reaching the bottom of the wells. EC showed remarkable changes in value, which was attributed to the presence of water-bearing
fractures in the hard rock areas. The results of this study are in good agreement with geophysical and geological findings.
In addition to identifying the water-bearing fractures, the EC logs also provide various other hydrological and hydrochemical
information, i.e., water table, total depth of the bore well, total dissolved solids (TDS), behavior of water–rock interaction,
water quality, information about the chemistry of aquifers, etc. 相似文献
(1) | Maheswaram (30 km South of Hyderabad): nine shallow bore wells in a watershed of 60 km2 in granitic aquifers, |
(2) | Wailpally (60 km East of Hyderabad): four shallow bore wells in a watershed of 50 km2 in granitic terrain. |
(3) | Sadras (60 km SSW of Chennai): four shallow bore wells in a watershed 12 km2 in a charnokite aquifers. |
145.
146.
Deficiencies of different existing models on ‘Reservoir Induced Seismicity’ have been discussed and a new mathematical model, which enhances a better understanding of triggering mechanism in terms of changes in effective stresses, in situ stresses and water level variations, has been discussed in this paper. In the model fractured rock is simulated by a fluid-filled elastic material subject to Mohr–Coulomb failure criterion. The model has been found to be capable of responding effectively to site specific attributes. It can recognize and explain the phenomenon of time lag observed in several actual cases. It is also capable of simulating stabilization of rock–reservoir system after a period of activities that follow the initial stage of filling. One dimensional and two dimensional, isotropic and anisotropic cases have been analysed and the model predictions have been found to agree qualitatively with the field observations. 相似文献
147.
In this paper we present a method for computint the equilibrium structures of rotationally distorted stars as well as rotationally and tidally distorted primary components of the stars in binary systems. The method is based on the averaging technique of Kippenhahn and Thomas (1970) and utilizes the concepts of Roche equipotentials (Kopal, 1972). The method takes into account terms up to second-order of smallness in the rotational and tidal distortion parameters. The use of the method in obtaining the equilibrium structures of certain rotationally and (or) tidally distorted models of Main-Sequence stars is also illustrated. 相似文献
148.
Rationale for the measurement of open-ocean tsunami signatures are presented, and available pertinent data are reviewed. Models for tsunami signature and background noise are proposed in order to synthesize an optimum tsunami receiver. Using these models, the minimum tsunami amplitude (in cm) to yield the probability of correct tsunami detectionP_{D} = 0.999 and probability of false alarmP_{F} = 10^{-3} is found to be0.718/sqrt{f_{0}} , wheref_{0} is the tsunami dominant frequency (in cycles/h). A realizable receiver is proposed and its performance is evaluated using actual tsunami signatures. It is demonstrated that the detection of a tsunami with an average amplitude as small as 0.7 cm is possible for theP_{D} andP_{F} as above. Simulation results using synthesized background noise are shown. Tidal effects on the receiver performance also are considered and are found negligible for a certain range of the receiver parameters, resulting in a considerable reduction of the signal processing required. 相似文献
149.
Anil Kumar Misra Anju Saxena Manish Yaduvanshi Ajai Mishra Yogendra Bhadauriya Alok Thakur 《Environmental Geology》2007,51(8):1361-1376
India is a vast country and is highly diversified in terms of natural resources and socio-economic setup. Moreover, its water
resources are unevenly distributed in space and time. With increasing population and increasing aspiration for improved standard
of living, there is an acute pressure on the demand and availability of water. Though the idea of interlinking of rivers is
not a new concept in India, it had rather persisted long back as much as in other countries of ancient civilization. National
Water Development Agency (NWDA) has given the real shape to the proposal of the interlinking of rivers of the country. In
India the river-linking project in a sensible and scientific manner will not only allow the prevention of the colossal wastage
of a vitally important natural resource, mitigate the flood and inundation by detaining flowing surface water of rainy seasons,
but also ensure availability of water to drier areas; combating both flood and drought simultaneously. Moreover, this project
will generate 34,000 MW of hydropower and irrigation of an additional 35 million hectares (135,135 square miles) of land.
Though linking of rivers may initially appear to be a costly proposition in ecological, geological, hydrological and economical
terms, in the long run the net benefits coming from it will far outweigh these costs or losses. However, in the absence of
any definite international legal framework, Bangladesh has raised objections against the project. This paper aims at looking
at this long-term plan, the project proposal, its involvement and impact not only on the states of India, India as a whole,
but also on its neighbouring nations which are linked with India through the waterways, and share the common climatic conditions
and economic status. 相似文献
150.
Four different solution models, the two-parameter Margules, the quasi-chemical (QC), the Wilson and the non-random two-liquid (NRTL) model, have been used for fitting the calorimetric excess enthalpy of solution for the following four binary silicate systems: anorthite-albite, pyrope-grossular, diopside-enstatite and diopside-Ca-Tschermak. All models except the Wilson model yield a satisfactory fit to the data but the NRTL model generally results in the lowest residuals. The use of NRTL and QC facilitates the study of the configurational and non-configurational parts of the excess entropy of mixing.Three different methods, namely those of Kohler, Wohl, and Hillert, have been used to combine binary solution properties to predict ternary solution properties. Comparison of computed excess free energy of mixing in a hypothetical solution shows that all the three methods are viable but the Kohler and Wohl methods are similar to each other and are significantly different from the Hillert method. The Kohler method with one or a combination of different binary models is recommended for predicting multicomponent solution properties.Abbreviations
G
ex
excess free energy of mixing
-
H
ex
excess enthalpy of mixing
-
S
ex
total excess entropy of mixing
-
S
ex
c
configurational excess entropy of mixing
-
W
ij
interaction energy parameter between speciesi andj
-
X
i
mole fraction of speciesi
- QC
quasi-chemical
- NRTL
non-random two-liquid
- M
Margules formulation
- W
Wohl's formulation
- RK
Redlich-Kister
- K
Bertrand-Kohler
- H
Hillert
- Di
diopside (CaMgSi2O6)
- En
enstatite (Mg2Si2O6)
- Py
pyrope (MgAl2/3SiO4)
- Gr
grossular (CaAl2/3SiO4)
- CaTs
Ca-Tschermak (CaAl2SiO6)
- Ab
albite (NaAlSi3O8)
- An
anorthite (CaAl2Si2O8) 相似文献