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11.
P. Krishnakumar C. Lakshumanan M. P. Jonathan M. Sundararajan M. Navarrete-Lopez 《Arabian Journal of Geosciences》2014,7(7):2655-2665
The concentration of trace metals like Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were studied in beach and estuarine sediments of the Velanganni Coast, South East coast of India to understand metal pollution due to urbanization/industrialization. This area was affected by the urbanization activity like untreated effluent discharge, transportation and incineration of solid waste, etc. In this context, quality of the sediments was evaluated based on the enrichment factor, geo-accumulation index (Igeo), pollution load index, and sediment quality guidelines. Furthermore, correlation matrix and principal compound analyses have been performed with SPSS 7.5 statistical software. The result illustrated that the metal enrichment is in the following order: Cd > Cr > Ni > Zn > Pb > Mn > Cu. The level of Igeo suggests that Cd has moderately polluted the sediment class. Similarly, principal component analysis showed that Cd and Pb accounted for the anthropogenic pollution, but Pb inferred as its tracers level. The results strongly indicate anthropogenic sources for moderate input of Cd contamination in to Velanganni coastal sediments. 相似文献
12.
C. Thivya S. Chidambaram R. Thilagavathi M. V. Prasanna C. Singaraja M. Nepolian M. Sundararajan 《Arabian Journal of Geosciences》2014,7(9):3767-3777
A study was carried out in the Madurai district of Tamil Nadu, India to identify the hydrogeochemical processes using factor analysis as a predictive tool. It also focuses on characterizing the samples of these factors with respect to standard geochemical plots. In order to obtain a synoptic view of the statistics and the geochemical processes, a total of 53 groundwater samples are collected representing the entire district. The major ions were analyzed; the order of ion dominance are Ca2+?>?Na+?>?Mg2+?>?K+?=?Cl??>?HCO? 3?>?H4SiO? 4?>?NO? 3?>?SO2? 4?>?P3? 4. The samples are classified according to three factors. Factor 1 shows strong positive loadings of Cl?, Ca2+, Mg2+, and NO? 3 with 36.98 % of the total variance (TV); factor 2 accounts for 13.72 % of TV with high loadings of Na+, K+, and HCO? 3; and factor 3 shows strong positive loadings of PO3? 4 and SO2? 4 with TV of 13.1 %. In the Piper plot, few samples fall in the mix region as evidenced by the mixing proportion of two samples using AQUACHEM software. The results suggest that different hydrogeochemical processes, like weathering, ion exchange processes, and anthropogenic activities (like sewage infiltration and agriculture), has predominant impact in the study area. Thus, the study highlights the factor analysis technique as a predictive and effective tool for groundwater evolution. 相似文献
13.
H. S. Sawant R. Ramesh J. R. Cecatto C. Faria F. C. R. Fernandes R. R. Rosa M. C. Andrade S. Stephany L. B. T. Cividanes C. A. I. Miranda L. C. L. Botti J. W. S. V. Boas J. H. Saito C. E. Moron N. D. Mascarenhas K. R. Subramanian M. S. Sundararajan E. Ebenezer M. R. Sankararaman 《Solar physics》2007,242(1-2):213-220
An East – West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira
Paulista (longitude 45°0′20″ W, latitude 22°41′19″ S) for observations of the Sun and some of the strong sidereal sources
by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array
and can be operated at any frequency in the range 1.2 – 1.7 GHz. The instrument has been in operation since November 2004
onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ∼3′ and 100 ms, respectively. Details of the
array, analog/digital receiver system, and a preliminary East – West one-dimensional solar image at the 1.6 GHz are presented
in this paper. 相似文献
14.
Grain size analysis and characterization of sedimentary environment along Thiruchendur coast, Tamilnadu, India 总被引：1，自引：0，他引：1
V. C. Rajganapathi N. Jitheshkumar M. Sundararajan K. H. Bhat S. Velusamy 《Arabian Journal of Geosciences》2013,6(12):4717-4728
Thiruchendur coast of southern Tamilnadu, India has been studied for grain-size spectrum and textural parameters namely mean, sorting, skewness and kurtosis. The grain-size spectrum shows a marked variation in the berm, high tide line (HTL) and low tide line (LTL) stretches. Variation in energy condition is controlled by geomorphology of the sedimentary beach. Textural pattern shows complicated profile as a result of the fluctuation in the physicochemical conditions due to the sediments and the marine interactions. Abundance of the medium sand to fine sand shows the prevalence of comparatively moderate- to low-energy condition in the Thiruchendur area. Linear discriminate function of the samples indicates an aeolian, shallow marine deposition environment and less influence of fluvial (7 %) process. CM diagram (C = one percentile in microns M = medium in microns) of Thiruchendur coast sediments suggests that deposition takes place by (1) rolling, (2) bottom suspension, (3) graded suspension. This is also supported by the wave energy in different stretches in beach line and also tractive current figure implies the sediments disturbed by the tractive and turbidity currents. The heavy minerals are concentrated in the berm (average, 11.8 %) and high tide line (average, 11.2 %) because of high-energy condition and aeolian action. Quartz microtextures show the mechanical action due to high-energy condition in Manapad and Kuduthalai areas, the chemical action because of to low-energy condition along the Thiruchendur, Kallamozhi areas. 相似文献
15.
The paper describes the application of the finite strip method, a modification of the finite element method, to determine the random response of rectangular plates. An example problem of a rectangular orthotropic plate, simply supported on two opposite edges and clamped on the other two, under acoustic white noise excitation is solved. 相似文献
16.
We present an inversion technique based on the Marquardt algorithm to estimate the depth of a 2.5-D sedimentary basin in addition
to the regional gravity anomaly that is associated with the residual gravity anomaly, wherein the density contrast varies
parabolically with depth. Forward modeling is carried out through a derived analytical gravity expression of a 2.5-D vertical
prism. Inversion of a theoretical gravity anomaly with and without a regional gravity anomaly illustrates the procedure that
it is found to be insensitive to the regional gravity effect. Furthermore, the algorithm is exemplified with the gravity anomalies
of the derived density-depth model of the Godavari subbasin, India with a parabolic density profile resulting in a more consistent
geological model rather than a constant density profile. The main advantage of this method is that it works well even when
the profile of interpretation does not bisect the strike length of the sedimentary basin. 相似文献
17.
A detailed hydrogeological investigations comprising well inventory, water level monitoring, lake bathymetry, infiltration and pump tests were carried out in a few selected observation wells in order to estimate transmissivity (T) and storativity (S) in all major lakes which are highly polluted by the discharge of sewage and other chemical effluents in greater Hyderabad. The salient features of results are presented lake wise which would be of immense use in restoration of all lakes. Also, the outcome of this study along with infiltration rates may be used for modeling in future to simulate the surface water-ground water interaction. 相似文献
18.
Bernhard Pracejus Narasimman Sundararajan Salah Al-Khirbash Talal Al-Hosni A. Ebrahimi Shakil Al-Bulushi Ali Al-Lazki Musadem Al-Maashani 《Chemie der Erde / Geochemistry》2018,78(4):479-489
This paper presents findings from a comprehensive geochemical and geophysical re-examination of known radiogenic anomalies in Tertiary limestones and (sub-)recent calcretes of southwestern Dhofar in the Sultanate of Oman. U-Th-enrichments seem to be associated with deep-rooted fault systems that cross-cut Corg-rich shales at depths of some 800–1000?m, which generally show elevated gamma-ray levels in southern Oman and act as the initial geochemical trap. Metals and radiogenic elements, such as K (max?1945?ppm), U (max?44?ppm), and Th (max?26?ppm) mobilised from these rocks and emplaced higher up in the faults must have constituted radiogenic lineaments at and near the surface (observed in a different but difficult to access location). However, successive weathering partially obscured such anomalies through further re-mobilisation/-mineralisation processes within the calcretes that also enriched Sr and V. In these carbonates, uranium correlates positively with Sr but not very well with V, while thorium shows moderate positive correlations with Sr and V. Both U and Th are also not present (i.e., below the detection limits of a few ppm) in a second sample group that represents background conditions. Being much more immobile than U, Th remained closer to the original western fault positions of the examined site (outlined by magnetics and VLF-EM during the surveys), while uranium moved down-dip over the plateau and through underlying sub-horizontal strata towards the eastern fault system. Here, supergene Sr-enriched calcite preferentially incorporated U, thus reflecting the observed U-Th fractionation. 相似文献
19.
An inversion technique using the Marquardt optimization is developed to interpret the gravity anomalies due to anticlinal and synclinal structures with density contrast varying continuously with depth. The algorithm simultaneously estimates the parameters of the respective models, in addition to the regional gravity background that is invariably associated with the residual gravity anomaly. Forward modelling is realized through analytically derived gravity expressions for the respective models in the space domain. The efficacy of the inversion is demonstrated with the gravity anomaly due to a theoretical model, in each case with and without the regional background. In addition, the applicability is illustrated using the gravity anomalies of the Pays De Bray anticline, situated north‐west of Paris, France. The interpreted depth of the Pays De Bray anticline using the present inversion compares well with the drilling depth. 相似文献
20.
Sundararajan N. Mohan N. L. Raghava M. S. Vijaya Rao S. V. Seshagiri 《Pure and Applied Geophysics》1985,123(4):557-566
The Hilbert transformH(x) applicable to vertical (Z), horizontal (H), and total (T) magnetic anomalies due to a thin dike of infinite depth extent is derived from the generalised expression of magnetic effectF(x). The depth and dip of the dike is extracted by a simple procedure making use ofF(x) andH(x). A modified version of the amplitude of the analytic signal is given to locate the origin. The abscissa of the point of intersection ofF(x) and the discrete Hilbert transformH(1.x) directly yields the depth to the top. An example for each case is considered theoretically to illustrate the process. Applicability of the method is examined on the vertical component of the well-known magnetic anomaly at Kiirunavaara in northern Sweden, originally described by Von Carlheim Gyllenskjold, as well as on total magnetic anomaly of Bensons Mines, U.S.A. 相似文献