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241.
Santosh Kumar Sarkar Henrique Cabral Mousumi Chatterjee Ines Cardoso Asok Kumar Bhattacharya Kamala Kanta Satpathy Mohammad Aftab Alam 《洁净——土壤、空气、水》2008,36(2):187-194
The suitability of using four bivalve molluscs (Sanguinolaria acuminata, Anadara granosa, Meretrix meretrix, and Pelecyora trigona) in biomonitoring of heavy metals (Cu, Pb, Cd, Zn, and Hg) collected from intertidal regions of the Sunderban mangrove wetland, northeastern part of the Bay of Bengal, were evaluated. Both speciesdependent variability and temporal variations were pronounced. A high degree of organ specificity was evident in the bivalves where gill and mantle exhibited higher metal accumulation due to ion exchange property of the mucous layer covering these organs while shells represent very poor accumulation. Elevated values of Zn and Cu reflect high potential for biomagnification through marine food chain. Metal concentrations in different body size groups of the bivalves do not follow uniform trend. Correlation coefficient between different metal couplings as tested statistically revealed significant coupling for Pb–Zn, Pb–Cu, Zn–Cu, and Hg–Cu. Concentrations of all the metals in specific organs (visceral mass, mantle and gill) of the bivalves exceeded the safe levels according to the international standards for metals compiled by Food and Agricultural Organization of the United Nations and would be of great risk for human consumption. It is concluded that the mussel and clam are suitable biomonitors to employ in programs designed to assess changes in metal pollution in the Sunderban mangrove wetland. 相似文献
242.
B. M. Gaensler † B. W. Stappers D. A. Frail D. A. Moffett ‡ S. Johnston S. Chatterjee 《Monthly notices of the Royal Astronomical Society》2000,318(1):58-66
We report on a sensitive survey for radio pulsar wind nebulae (PWN) towards 27 energetic and/or high-velocity pulsars. Observations were carried out at 1.4 GHz using the Very Large Array and the Australia Telescope Compact Array and utilized pulsar-gating to search for off-pulse emission. These observing parameters resulted in a considerably more sensitive search than previous surveys and could detect PWN over a much wider range of spatial scales (and hence ambient densities and pulsar velocities). However, no emission clearly corresponding to a PWN was discovered. Based on these non-detections we argue that the young and energetic pulsars in our sample have winds which are typical of young pulsars, but produce unobservable PWN because they reside in low-density ( n ∼0.003 cm−3 ) regions of the interstellar medium. However, non-detection of PWN around older and less energetic pulsars can only be explained if the radio luminosity of their winds is less than 10−5 of their spin-down luminosity, implying an efficiency at least an order of magnitude smaller than that seen for young pulsars. 相似文献
243.
S. Chatterjee L. M. Pande S. K. Subramanian S. K. Saha C. J. Thampi 《Journal of the Indian Society of Remote Sensing》1990,18(4):15-23
Visual Interpretation of Landsat Imagery (TM-FCC) on 1∶250,000 scale covering 2410 sq km in a part of Mahandi Delta, Kataka district, Orissa was carried out for delineating the physiographic units. The major physiographic units identified and delineated were ‘Delta plain’ and ‘Coastal plain’. These units were further subdivided on the basis of image elements. The abstraction level attained was ‘Family’ based on Soil Taxonomy. The soils of the beach were classified as Typic Ustipsamments; old coastal plain as fine, Typic Haplaquept and coarse loamy Aquic Ustifluvent; Tidal flat as fine Typic Haplaquept and fine loamy Aquic Ustifluvent; mud flat as fine Typic Haplaquept; Levee-plain complex as Typic Ustipsamment and fine loamy Typic Ustorthent; old Delta plain as fine Udic Ustochrept and Aeric Haplaquept and recent delta plain as fine loamy and coarse loamy Typic Ustorthent. The soils are mixed in mineralogy and Isohyperthermic in temperature regime. 相似文献
244.
Silica and volatile-element metasomatism of Archean mantle: a xenolith-scale example from the Kaapvaal Craton 总被引:5,自引:1,他引:4
D.?R.?BellEmail author M.?Grégoire T.?L.?Grove N.?Chatterjee R.?W.?Carlson P.?R.?Buseck 《Contributions to Mineralogy and Petrology》2005,150(3):251-267
Textural evidence in a composite garnet harzburgite mantle xenolith from Kimberley, South Africa, suggests metasomatism of
a severely melt-depleted substrate by a siliceous, volatile-rich fluid. The fluid reacted with olivine-rich garnet harzburgite,
converting olivine to orthopyroxene, forming additional garnet and introducing phlogopite, and small quantities of sulfide
and probable carbonate. Extensive reaction (>50%) forming orthopyroxenite resulted from channelized flow in a vein, with orthopyroxene
growth in the surrounding matrix from a pervasive grain-boundary fluid. The mineralogy of the reaction assemblage and the
bulk composition of the added component dominated by Si and Al, with lesser quantities of K, Na, H, C and S, are consistent
with experimental studies of hybridization of siliceous melts or fluids with peridotite. However, low Na, Fe and Ca compared
with melts of eclogite suggest a fluid phase that previously evolved by reaction with peridotitic mantle. Garnet and phlogopite
trace element compositions indicate a fluid rich in large-ion lithophile (LIL) elements, but poor in high field-strength elements
(HFSE), qualitatively consistent with subduction zone melts and fluids. An Os isotope (TRD) model age of 2.97 ± 0.04 Ga and lack of compositional zonation in the xenolith indicate an ancient origin, consistent with
proposed 2.9 Ga subduction and continental collision in the Kimberley region. The veined sample reflects the silicic end of
a spectrum of compositions generated in the Kimberley mantle lithosphere by the metasomatizing effects of fluids derived from
oceanic lithosphere. These results provide petrographic and chemical evidence for fluid-mediated Si-, volatile- and trace-element
metasomatism of Archean mantle, and support models advocating large-scale modification of regions of Archean subcontinental
mantle by subduction processes that occurred in the Archean. 相似文献
245.
Niranjan D. Chatterjee 《Contributions to Mineralogy and Petrology》1973,42(3):259-271
The reaction 3 Na-montmorillonite + 2 albite 3 paragonite + 8 quartz has been studied experimentally using starting materials composed of natural low albite, kaolinite and quartz. Rate studies at 2, 4 and 7 kb demonstrate that the reaction takes place at 335–315° C from lower to higher pressures. Attempts to reverse this reaction with runs lasting several months were without success. Comparison with pertinent data from natural mineral assemblages indicate that despite non-reversal, the data presented here may be very near to the true lower thermal compatibility limit of the assemblage quartz-paragonite.The above reaction becomes metastable beyond the upper pressure stability limit of the phase Na-montmorillonite; it is replaced here by another reaction 1 albite + 1 kaolinite 1 paragonite + 2 quartz + 1 H2O, as suggested originally by Zen (1960). A P-T-grid showing possible compatibility relations of the assemblage quartz-paragonite is provided (Fig. 4). Perusal of natural assemblages belonging to the subsystem Na2O-Al2O3-SiO2-H2O lends credence to this grid.In course of the rate studies reported here, various regular paragonite-sodium montmorillonite mixed-layer phases were encountered (Fig. 2); the 11 regular mixed-layer phase represents the synthetic analogue of the mineral rectorite (sometimes called allevardite), widely recorded from deep diagenetic and anchimetamorphic environments. Results of rate-studies (Fig. 3) suggest that the mixed-layer phases are all transient, metastable products obtained during the transformation of the albite-Na-montmorillonite assemblage to paragonite-quartz. As such, rectorite and related mixed-layer phases on the join montmorillonite-paragonite, are always less stable relative to the assemblage Na-montmorillonite-paragonite. 相似文献
246.
Summary Effects of non-homogeneity in respect of rigidity have been computed in the case of a gravitating sphere with a rigid core. For an isotropic spherical shell the effect of variation of rigidity has been calculated when the shell is under pressure or when the shell is subjected to some steady temperature on its internal surface. 相似文献
247.
Shyamal Kumar Chatterjee 《Pure and Applied Geophysics》1969,76(1):107-109
Summary In the present note the author has considered the problem of torsional vibration of a semi-infinite non-homogeneous elastic medium by an exponentially decreasing impulsive twist applied on the plane surface. 相似文献
248.
Dr. A. K. Bhattacharya Mr. B. K. Chatterjee 《International Journal of Earth Sciences》1964,53(2):758-779
Pre-Cambrian Geology of an area of about 14 sq. miles has been investigated in this paper. The oldest rock is a very small patch of serpentinite, tentatively correlated with the huge ultrabasic body at Jojohatu, some 10 miles north. Granite and Newer dolerite are intrusive rocks of the area. Kolhan series, resting unconformably on Granite and showing facies variation from basal sandstone conglomerate to phyllitic shale through sandstone and impersistent limestone in a thickness of only a few tens of metres, is a shallow epicontinental deposit. Kolhan sandstone, rich in hematitic cement, is an argillaceous orthoquartzite practically devoid of feldspar and is very poor in heavy and accessory minerals. It is richly current bedded, immature, bimodal, fine grained, positively skewed and well sorted. Kolhan limestone is recrystallized micrite, its lower horizon is mostly high grade and contains pink calcite and quartz crystals in cavities. Its upper horizon is low grade, phyllitic and argillaceous and is partly metasomatic and exhibits contemporaneous deformation structures like hassock bedding and slickenside (slickolites?). Kolhan phyllitic shale exhibits effects of Singhbhum orogeny in development of cleavage and crumpling of foliation. Dirty green vug quartz contains abundant oriented microscopic chlorite inclusions. Non-metallic and metallic mineralization in Kolhans is represented by limestones, and local hematite-molybdenite and iron-rich manganese ore respectively. 相似文献
249.
Nonlinear dust ion acoustic solitary waves (DIASW) in dusty plasma are studied incorporating kinematic viscosity, using Sagdeev’s pseudopotential approach. The effects of kinematic viscosity and the nonextensive parameter q on the features of DIASW are investigated in some detail. 相似文献
250.
For the critical values of the parameters q and V, the work (Samanta et al. in Phys. Plasma 20:022111, 2013b) is unable to describe the nonlinear wave features in magnetized dusty plasma with superthermal electrons. To describe the nonlinear wave features for critical values of the parameters q and V, we extend the work (Samanta et al. in Phys. Plasma 20:022111, 2013b). To extend the work, we derive the modified Kadomtsev-Petviashvili (MKP) equation for dust ion acoustic waves in a magnetized dusty plasma with q-nonextensive velocity distributed electrons by considering higher order coefficients of ?. By applying the bifurcation theory of planar dynamical systems to this MKP equation, the existence of solitary wave solutions of both types rarefactive and compressive, periodic travelling wave solutions and kink and anti-kink wave solutions is proved. Three exact solutions of these above waves are determined. The present study could be helpful for understanding the nonlinear travelling waves propagating in mercury, solar wind, Saturn and in magnetosphere of the Earth. 相似文献