A Single Step Acid Assisted Microwave Digestion Method for the Complete Dissolution of Bauxite and Quantitation of its Composition (Al2O3, Fe2O3, SiO2, TiO2, Cr2O3, MgO,MnO and V2O5) by ICP-AES     

Ankam Durga Prasad  Lori Rastogi  Shanmugam Thangavel  Kulamani Dash 《Geostandards and Geoanalytical Research》2023,47(2):403-413

An acid assisted microwave-based method for the complete dissolution of bauxite using mixture of H₂SO₄, H₃PO₄ and HF acids in a single step was developed for the determination of various analytes (Al₂O₃, Fe₂O₃, SiO₂, TiO₂, Cr₂O₃, MgO, MnO and V₂O₅) using ICP-AES. The method was validated with respect to ruggedness, linearity, trueness, precision, limit of detection (LOD), limit of quantification (LOQ), working range and measurement uncertainties by analysing a bauxite reference material (Alcan BXT-12) and four certified reference materials (IPT-131, BXBA-4, NIST SRM 600, NIST SRM 697). The expanded uncertainties obtained for Al₂O₃ (40.0%), Fe₂O₃ (17.0%), SiO₂ (20.3%), TiO₂ (1.31%), Cr₂O₃ (0.024%), MgO (0.05), MnO (0.013), and V₂O₅ (0.60%), were 0.80, 0.40, 0.50, 0.033, 0.0008, 0.002, 0.0007 and 0.002 respectively, which are fit for the intended use to characterise bauxite. The developed method was also evaluated through participation in an interlaboratory comparison exercise organised by the Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, India, using bauxite sample (BXT-JNA), with satisfactory z-scores achieved.  相似文献   

Reservoir capacity estimation of Singoor reservoir,India, by per-pixel and sub-pixel processing of multi-date satellite images     

Veeraraghu S. Jeyakanthan  Shanmugam Sanjeevi 《国际地球制图》2013,28(4):305-320

Traditional approaches of image classification, such as maximum likelihood and the band thresholding method, involve the per-pixel approach to delineate the water spread area of a reservoir. One of the limitations of these approaches is that the pixels representing the reservoir border, containing a mixture of water, soil and vegetation, are classified entirely as water, thereby resulting in inaccurate estimates of the water spread area. To compute the water spread area accurately, the sub-pixel approach has been used in this study. The water spread areas extracted using per-pixel and sub-pixel approaches from IRS-1D and P6 satellite image data were in turn used to quantify the capacity of the Singoor reservoir, Andhra Pradesh, India. The estimated capacity of the reservoir using the per-pixel and sub-pixel approaches was 727.75 Mm³ and 716.11 Mm³, respectively. The validation shows that the sub-pixel approach produced much less error (1.08%) than the per-pixel based approach (3.14%).  相似文献   

Spatial and temporal aspects of phytoplankton blooms in complex ecosystems off the korean coast from satellite ocean color observations     

Yu -Hwan Ahn  Palanisamy Shanmugam  Kyung- Il Chang  Jeong -Eon Moon  Joo -Hyung Ryu 《Ocean Science Journal》2005,40(2):67-71

Complex physical, chemical and biological interactions off the Korean coast created several striking patterns in the phytoplankton blooms, which became conspicuous during the measurements of ocean color from space. This study concentrated on analyzing the spatial and temporal aspects of phytoplankton chlorophyll variability in these areas using an integrated dataset from a Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Advanced Very High Resolution (AVHRR) sensor, and Conductivity Temperature Depth (CTD) sensor. The results showed that chlorophyll concentrations were elevated in coastal and open ocean regions, with strong summer and fall blooms, which appeared to spread out in most of the enclosed bays and neighboring waters due to certain oceanographic processes. The chlorophyll concentration was observed to range between 3 and 54 mg m^-3 inside Jin-hae Bay and adjacent coastal bays and 0.5 and 8 mg m^-3 in the southeast sea offshore waters, this gradual decrease towards oceanic waters suggested physical transports of phytoplankton blooms from the shallow shelves to slope waters through the influence of the Tsushima Warm Current (TWC) along the Tsushima Strait. Horizontal distribution of potential temperature (θ) and salinity (S) of water off the southeastern coast exhibited cold and low saline surface water (θ<19°C; S<32.4) and warm and high saline subsurface water (θ>12°C; S>34.4) at 75dBar, corroborating TWC intrusion along the Tsushima Strait. An eastward branch of this current was called the East Korean Warm Current (EKWC), tracked with the help of CTD data and satellite-derived sea surface temperature, which often influenced the dynamics of mesoscale anticyclonic eddy fields off the Korean east coast during the summer season. The process of such mesoscale anticyclonic eddy features might have produced interior upwelling that could have shoaled and steepened the nutricline, enhancing phytoplankton population by advection or diffusion of nutrients in the vicinity of Ulleungdo in the East Sea.  相似文献   

Discussion on Mulder et al. (2001, Geo-Marine Letters 21: 86–93) Inversely graded turbidite sequences in the deep Mediterranean. A record of deposits from flood-generated turbidity currents?     

G. Shanmugam 《Geo-Marine Letters》2002,22(2):108-111

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Embryology of Maldives clownfish, Amphiprion nigripes (Amphiprioninae)     

Swagat Ghosh  Thipramalai Thankappanpillai Ajith Kumar  Thangavel Balasubramanian 《中国海洋大学学报(英文版)》2012,11(2):174-180

This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions.  相似文献   

High energy X-γ ray spectrometer on the Chandrayaan-1 mission to the Moon     

J. N. Goswami  D. Banerjee  N. Bhandari  M. Shanmugam  Y. B. Acharya  D. V. Subhedar  M. R. Sharma  C. N. Umapathy  P. Sreekumar  M. Sudhakar  L. Abraham  P. C. Agrawal 《Journal of Earth System Science》2005,114(6):733-738

The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX) for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the²³⁸U and²³²Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on the lunar surface by detection of the 46.5 keV line from radioactive²¹⁰Pb, a decay product of the gaseous²²²Rn, both of which are members of the²³⁸U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride (CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload configuration and plans for its realization  相似文献   

Anatomy of the middle ordovician sevier shale basin,eastern Tennessee     

Ganapathy Shanmugam  Kenneth R. Walker 《Sedimentary Geology》1983,34(4):315-337

The Sevier Shale basin in eastern Tennessee comprises one of the thickest clastic sequences (nearly 2500 m) of Middle Ordovician age in North America. The lower one-half of the sequence is composed of Lenoir, Whitesburg, Blockhouse and Sevier Formations, in ascending order. The sequence ranges in age from Whiterockian to lower Wilderness in North American stages.The Middle Ordovician sequence exhibits tidal flat (Mosheim Member of Lenoir Fm.), subtidal (main body of Lenoir Fm.), slope (Whitesburg Fm.), anoxic basin (Blockhouse Fm), turbidite and contourite (Sevier Fm.) facies. The Sevier basin evolved in five stages: First, a widespread marine transgression initiated carbonate-shelf deposition in the study area. Second, a major tectonic downwarping event caused the stable shelf to break and subside rapidly at a rate of 60–65 cm 1000 yrs^?1, and areas of shelf facies became areas of slope and basin facies. Third, global transgressions maintained the deep anoxic conditions for nearly 10 Ma. Fourth, turbidites began to fill the basin from a westward-prograding submarine fan system. Fifth, contour currents reworked the turbidites and progressively ventilated the Sevier basin. The basin-filling process terminated with shallow-water/subaerial clastics at the end of Middle Ordovician.  相似文献   

A Natural Gamma Spectrometry approach to derive clay mineral composition and depositional environment of a reservoir facies in Ramnad sub-basin,Cauvery basin,southern India     

D. Srikant  P. Shanmugam 《Journal of the Geological Society of India》2017,89(5):521-531

The Ramnad sub-basin is one of the most explored for hydrocarbons in Cauvery basin. A number of exploratory wells have been drilled to delineate hydrocarbon bearing horizons. Nannilam Formation of Santonian–Campanian age hosts considerable thickness of reservoir facies. The reservoir facies is mainly clastics such as sandstone and siltstone with lot of clay content. In addition to normal logs, the NGS (Natural Gamma Ray Spectrometry) logs are widely employed to estimate sediment composition and broad depositional environment of reservoir facies. The present study employs and analyses NGS logs of four well sections from Kanjirangudi area of Ramnad sub-basin to determine the clay mineral composition and depositional environment of Nannilam Formation. Thorium (Th), potassium (K) and uranium (U) concentrations and their interrelationships reveal that montmorillonite, illite and kaolinite are the dominant clay minerals. The clay mineral composition suggests that the sediments of the Nannilam Formation were derived from a provenance of acid igneous rocks during warm, humid and tropical conditions. Also, the ratios of Th/K indicate a deep open marine condition under which the sediments of the Nannilam Formation were deposited. These results would aid a better understanding and characterization of reservoir facies in the sub-basin.  相似文献