http://www.sciencedirect.com/science/article/pii/S1674987113000340     

Suman Kilaru  Bandaru Karunakar  Goud Vijay  Kumar Rao 《地学前缘(英文版)》2013,4(6):717-728

Regional surface gravity data and global satellite magnetic data have been utilized to generate a preliminary model of the crustal structure along a southwest-northeast profile （Gadra-Fatehpur） through western Rajasthan.The study area represents the western part of the Indian continental landmass which has undergone several major episodes of repeated subduction/collision,plume traces and rifting from Archaean to recent times.The temporal and spatial relationship between the various geotectonic provinces is quite complex,thereby limiting the emergence of a suitable crustal structure model for this region.Exposures of the Malani Igneous Suite （MIS）,a product of bimodal volcanism （～780 Ma）,and considered to be the third largest felsic magmatic province of the world,is evident along the profile and also to the southwest of the study area.The easternmost part of the profile is close to the DAFB （Delhi Aravalli Fold Belt）,a Proterozoic orogenic belt.This study probes the geometry of the different crustal units in terms of density and susceptibility variations in order to decipher the imprints of the major tectonic processes the region has undergone.In order to decipher the crustal geometry of the Gadra-Fatehpur profile,two NW-SE gravity and magnetic profile vertical sections （A-A＇ in the south and B-B＇ in the north） are modelled on the basis of the constraints provided from previous seismic models.The crustal model of the Gadra-Fatehpur profile is composed of alluvium,Tertiary sediments,MIS,Marwar Supergroup,low-density layers （LDLs） and the middle-lower crustal layers,with a distinct change in configuration from the southwest to northeast.The Moho dips from SW to NE,the MIS in the SW gives way to the thick pile of the Marwar Supergroup to the NE.The evolution of MIS has been suggested to have occurred as a consequence of delamination of the upper mantle.LDLs are incorporated in Gadra-Fatehpur model.In the SW,LDL （2550 kg/m3） lies below the MIS in the NE,another LDL （2604 kg/m3） is depicted below the mid-crustal layer.  相似文献   

Effect of extracellular polymeric substances on sludge reduction potential of Bacillus licheniformis   总被引：1，自引：0，他引：1  

J. Merrylin  S. Kaliappan  S. Adish Kumar  I. T. Yeom  Banu J. Rajesh 《International Journal of Environmental Science and Technology》2013,10(1):85-92

The disposal of wastewater sludge generated during the treatment of the various municipal and industrial wastewaters is a major environmental problem. In this study the thermophilic bacterium Bacillus licheniformis, which enhances the efficiency of sludge reduction, was isolated from waste activated sludge acclimated to 55 °C. The resulting suspended solids’ degradation was 12 % and chemical oxygen demand solubilization was 18 %. To further enhance the sludge reduction potential, extra polymeric substances, which play a major role in the formation of flocs, were removed. A chemical extractant, ethylenediaminetetraacetate that is also a cation binding agent, was used to remove the extra polymeric substances. After the removal of extra polymeric substances, the suspended solids’ degradation increased from 12 to 23 % and the chemical oxygen demand solubilization increased from 18 to 25 %. These observations confirm that Bacillus licheniformis enhanced sludge reduction in non-flocculated sludge (with the removal of extra polymeric substances) as compared to flocculated sludge (without the removal of extra polymeric substances).  相似文献   

The radius spectrum of solid grains settling in gaseous giant protoplanets     

G. C. Paul  M. M. Rahman  D. Kumar  M. C. Barman 《Earth Science Informatics》2013,6(3):137-144

Growth of grains having different initial sizes (10^?3 cm?≤?r ₀?≤?1 cm) has been investigated by coagulation processes inside gas giant protoplanets, formed by disk instability, in the mass range 0.3 to 10 Jovian masses. In doing so, we have determined distribution of thermodynamic variables inside the protoplanets and using the results we have determined growth of the grains having assumed initial sizes. Regarding the transference of heat inside the protoplanets, we have considered the possible two cases of interest, namely convection and conduction-radiation. The results of our calculation show that growth of the grains depends on protoplanetary masses and on initial states of the protoplanets and eventually all the grains having assumed different initial sizes acquire almost the same distribution in the central regions of respective protoplanets in the respective cases.  相似文献   

Arsenic mobilization in alluvial soils of Punjab, North–West India under flood irrigation practices     

H. S. Hundal  Kuldip Singh  Dhanwinder Singh  Raj Kumar 《Environmental Earth Sciences》2013,69(5):1637-1648

A laboratory investigation was carried out to examine the mechanism of arsenic (As) mobilization under flooded conditions (24 and 240 h) in 18 alluvial soils of Punjab, North–West India. Total dissolved As increased from a range of 3–16 μg L^?1 (mean 9 μg L^?1) to a range of 33–1,761 μg L^?1 (mean 392 μg L^?1) with the increase in flooding period from 24 to 240 h. The amount of As mobilization varied depending upon redox potential (pe) created by flooding conditions. After 24 h of flooded conditions, pe of soil water suspension ranged from ?1.75 to 0.77 (mean ?0.24). Increasing the flooding period to 240 h, pe of soil water suspension decreased in the range of ?4.49 to ?2.74 (mean ?3.29). Pourbaix diagram identified arsenate (HAsO₄ ^2?) as predominant species in most of the alluvial soil–water suspensions under oxidized conditions, after 24 h of equilibration period, which ultimately transformed to arsenite (H₃AsO₃ ⁰) after 240 h of anaerobic condition due to more reduced status. The solid phase identified was orpiment (As₂S₃). Identification of iron and manganese species in alluvial soil water suspension by Pourbaix diagram indicated decline in both soluble Fe²⁺ and SO₄ ^2? concentration due to the formation of iron sulfide mineral phase after 240 h under anaerobic conditions. In these soils, decline in soluble Fe was also due to the precipitation of vivianite [Fe₃(PO₄)₂·8H₂O]. Elevated arsenic content and low pe value were measured in aquifers located in paddy growing fields comparative to aquifers of other sites. Large degree of variability in As concentrations was recorded in aquifers located at same sites. Thus, it is better to analyze each aquifer for their As content rather than to depends on the prediction on As content of neighbouring wells. The present investigation elucidates that flood irrigation practices in Punjab for growing paddy crop could induce the geochemical conditions favorable to mobilize arsenic from surface soils which could eventually elevate its content in the underlying shallow aquifers. Water abstracted from these aquifers by hand pumps or tube wells for drinking purposes could create hazards for local population due to loading with arsenic concentration above the safe limits. Thus, to avoid further contamination of shallow aquifers with arsenic, it is advisable to shift the flooded rice cultivation to other upland crops having lesser water requirement.  相似文献   

Chemometric analysis to infer hydro-geochemical processes in a semi-arid region of India   总被引：1，自引：0，他引：1  

Chander Kumar Singh  Satyanarayan Shashtri  Kumari Rina  Saumitra Mukherjee 《Arabian Journal of Geosciences》2013,6(8):2915-2932

Groundwater exploitation in Punjab has increased in last few decades due to rapid increase in industrialization, population, crop production, and erratic monsoon. In the present study, groundwater samples from 29 locations were collected and analyzed for almost all major anions, cations, and heavy metals. The analyzed parameters formed the attribute database for statistical analysis. The study approach included multivariate statistical analysis of hydro-chemical data to identify hydro-geochemical processes occurring in the study area and its relation to groundwater quality. The principal component analysis produced seven significant factors that explained nearly 77 % of the cumulative variance. Factor 1 explained nearly 22.05 % of dataset with variables loading indicating mineralization of geological component of soil. Trilinear plot and other graphical methods were also used to identify chemical facies of groundwater and geochemical processes occurring in study area. The water type in the study area is of Na/K–Mg–HCO₃ type. It was found that the general hydro-geochemistry of groundwater in the study area dominated is by the processes such as carbonate/silicate weathering, ion-exchange, and dissolution. Thus, statistical methods can prove to be an effective tool understanding hydro-geochemistry of a region along with conventional graphical methods.  相似文献   

Recent benthic foraminifera and their distribution between Tuticorin and Tiruchendur, Gulf of Mannar, south-east coast of India     

A. Solai  M. Suresh Gandhi  N. Rajeshwara Rao 《Arabian Journal of Geosciences》2013,6(7):2409-2417

Foraminifera have been successful inhabitants of every aquatic environment from deep oceans to brackish water lagoons, estuaries and even rarely in freshwater streams, lakes, etc. In order to know their distribution in different offshore habitats, the present study has been undertaken between Tuticorin and Tiruchendur, wherein 31 bottom sediment and water samples were collected. Benthic foraminiferal taxa belonging to four suborders (Textulariina, Miliolina, Lagenina and Rotaliina), 14 superfamilies, 25 families, 45 genera and 66 species have been identified; three planktonic species (suborder Globigerinina) have also been identified. An increase in total foraminiferal distribution with depth has been observed, except off Tiruchendur. Living/dead ratios range from 1.57% to 10.02%, indicating a low to moderate rate of sedimentation in this region. Off Punnaikayal and Tiruchendur, the rate of sedimentation is more at greater depths; at other stations, however, it is higher at relatively shallower depths. Based on this study, it is concluded that fluctuations in the distribution of foraminifera are mainly controlled by coastal morphology, wave dynamics, bathymetry and environmental parameters.  相似文献   

Evaluation of seismogenesis behavior in Himalayan belt using data mining tools for forecasting     

Pushan Kumar Dutta  O. P. Mishra  Mrinal Kanti Naskar 《Central European Journal of Geosciences》2013,5(2):236-253

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Textural and Mineralogical Characteristics of the Beach Sands of Tamil Nadu, Southern India     

C.G. Chandrasekaran  K.V. Muralidharan  K. Joshi Nirmal Kumar 《Gondwana Research》2001,4(4):588

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Observations of intensity oscillations in a prominence-like cool loop system as observed by SDO/AIA: evidence of multiple harmonics of fast magnetoacoustic waves     

A. K. Srivastava  B. N. Dwivedi  Mukul Kumar 《Astrophysics and Space Science》2013,345(1):25-32

Using SDO/AIA 304 Å channel, we study the evolution of weak intensity oscillations in a prominence like cool loop system observed at North-West limb on 7 March 2011. We use the standard wavelet tool to produce statistically significant power spectra of AIA 304 Å normalized fluxes derived respectively near the apex and footpoint of the fluxtube. We find periodicities of ≈667 s and ≈305 s respectively near apex and above footpoint with significance level >98 %. Observed statistically significant periodicities in the tube of projected length ≈170 Mm and width ≈10 Mm, are interpreted as most likely signature of evolution of various harmonics of tubular fast magnetoacoustic waves. Sausage modes are unlikely though they are compressive as they need bulky and highly denser loop system for their evolution for sustaining such large periods. We interpret the observed periodicities as multiple harmonics (fundamental and first) of fast magnetoacoustic kink waves that can generate some weak density perturbations (thus intensity oscillations) in the tube and can be observed pertaining to periodic variation in plasma column depth as tube is oblique in projection with respect to line-of-sight. The period ratio P ₁/P ₂=2.18 is observed in the fluxtube, which is the signature of the magnetic field divergence of the cool loop system. We estimate tube expansion factor as 1.27 which is typical of EUV bipolar loops in the solar atmosphere. We estimate the lower bound average magnetic fields ranging from ≈9 to 90 Gauss depending upon typical densities as 10⁹–10¹¹ cm^?3 in the observed prominence-like cool loop system. We also observe the first signature of lowering fundamental mode period by a factor 0.85 due to cooling of this loop system.  相似文献   

Head-on collisions of ion-acoustic Korteweg-de Vries/modified Korteweg-de Vries solitons in a magnetized quantum electron-positron-ion plasma     

Malay Kumar Ghorui  Utpal Kumar Samanta  Prasanta Chatterjee 《Astrophysics and Space Science》2013,345(2):273-281

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