Competitive adsorption behavior of selected heavy metals in three soil types of India amended with fly ash and sewage sludge   总被引：3，自引：0，他引：3  

H.?Veeresh  S.?TripathyEmail author  D.?Chaudhuri  B.?R.?Hart  M.?A.?Powell 《Environmental Geology》2003,44(3):363-370

Laboratory batch experiments were carried out to study the competitive sorption behavior of metals in three types of Indian soils, differing in their physicochemical properties: acid laterite (SL1), red alfisol (SL2) and black vertisol (SL3) treated with different proportions of fly ash and sewage sludge mixture. Representative samples were equilibrated with 10 to 200 µM L ^-1 concentrations of metals simultaneously containing Cd, Cu, Ni, Pb and Zn in 5 mM of Ca(NO ₃) ₂ solution. In most of the cases the affinity sequence of metals was Pb>Cu>Zn>Ni>Cd based on their amount of sorption, which varied little with either metal equilibrating concentrations or the soil/mixture type. The observed metal affinity sequences in different soils amended with mixtures were compared to the predicted affinity sequences based on metal properties and a good match was found with those predicted by metal hydrolysis constants. This indicated that formation and subsequent sorption of metal hydrolysis products on soil surface is the predominant mechanism for sorption. In all the cases, Pb and Cu showed higher affinity followed by Zn, Ni or Cd. The increase in the metal additions further enhanced the competition among metals for exchange sites. Adsorption isotherms showed that metal sorption was linearly related to its concentration in the equilibrium solution. The distribution coefficients (K _D) computed from the slopes of linear regression for different metals were higher in SL3 than in both SL2 and SL1. All the mixture amended soils produced higher K _D values than their respective controls. Selectivity between metals resulted in the following affinities based on their K _D values—Pb>Cu>Zn>Ni or Cd—which was in line with the value of the hydrolysis constant of the metals under study.  相似文献   

Small Amplitude Nonlinear Dust Acoustic Wave Propagation in Saturn's F, G and E Rings     

Samiran Ghosh  Tushar K. Chaudhuri  S. Sarkar  Manoranjan Khan  M.R. Gupta 《Astrophysics and Space Science》2001,278(4):465-477

Nonlinear properties of small amplitude dust acoustic waves, incorporatingboth the ion inertial effect and dust drift effect have been studied.The effect of dust charge variation is also incorporated. It is seen thatdue to the dust charge variation, a Korteweg-de Vries (KdV) equationwith positive or negative damping term depending on the wave velocityand the ring parameters governes the nonlinear dust acoustic wave. It isseen that the damping or growth arises due to the assumption that dusthydrodynamical time scale is much smaller than that of the dust chargingscale. This assumption is valid only for planetary rings such as Saturn'sF, G and E rings. Numerical investigations reveal thatall the three rings in F, G and E, dust acoustic solitary wave admits both negative and positive potentials. Instability arises from the available freeenergy of drift motion of dust grains only for the wave with wave velocity 0, the drift velocity of the dust.  相似文献   

Climbing ripple structure and associated storm-lamination from a Proterozoic carbonate platform succession: Their environmental and petrogenetic significance     

Asru K Chaudhuri 《Journal of Earth System Science》2005,114(3):199-209

The Mesoproterozoic Pandikunta Limestone, a shallow water carbonate platform succession in the Pranhita-Godavari Valley, south India, displays well developed climbing ripple lamination and storm deposited structures, such as HCS, wave ripple-lamination, combined-flow ripple-lamination and low angle trough cross-stratification. Different types of stratification developed in calcisiltite with minor amounts of very fine quartz sand and silt. The climbing ripple structures exhibit a complex pattern of superposition of different types (type A, B and S) within cosets pointing to a fluctuating rate of suspension depositionversus bedform migration, and an unsteady character of the flow. Close association of climbing ripple structures, HCS with anisotropic geometry, wavy lamination and combined-flow ripple-lamination suggest that the structures were formed by storm generated combined-flow in a mid-shelf area above the storm wave base. The combined-flow that deposited the climbing ripple structures had a strong unidirectional flow component of variable magnitude. The climbing ripple structure occurs as a constituent of graded stratified beds with an ordered vertical sequence of different types of lamination, reflecting flow deceleration and increased rate of suspension deposition. It is inferred that the beds were deposited from high-density waning flows in the relatively deeper part of the ancient shelf. The structures indicate that the Pandikunta platform was subjected to open marine circulation and intense storm activities. The storm deposited beds, intercalated with beds of lime-mudstone, consist primarily of fine sand and silt size carbonate particles that were hydrodynamically similar to quartz silt. Detrital carbonate particles are structureless and are of variable roundness. The particles were generated as primary carbonate clasts in coastal areas by mechanical disintegration of rapidly lithified beds, stromatolites or laminites, and the finest grade was transported to the offshore areas by storm-generated currents.  相似文献   

Mode‐acceleration approach to seismic response of multiply‐supported secondary systems     

V. Surya Chandra Rao  Samit Ray Chaudhuri  Vinay K. Gupta 《地震工程与结构动力学》2002,31(8):1603-1621

A mode‐acceleration approach has been proposed for estimating the seismic response of a linear, classically‐damped, multiply‐supported secondary system within the framework of a power spectral density function (PSDF)‐based stochastic approach, while the primary system is linear and classically‐damped. Response transfer functions have been formulated in terms of chosen numbers of fixed‐base modes of the primary and secondary systems. The proposed approach does not involve the determination of combined system properties, and is applicable to the secondary systems with high mass ratios also. Through a few example primary–secondary systems and an example band‐limited white noise excitation, it has been shown that this approach leads to reasonably accurate results when only a few primary and secondary modes are to be considered. The proposed formulation has been used to obtain input data for a decoupled response spectrum analysis of secondary systems. This data accurately accounts for the effects of interaction between the primary and secondary systems. It is shown to lead to substantial reductions in the errors associated with the envelope spectrum method in the case of moderately heavy to heavy secondary systems and when the spatial coupling does not play a major role. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

A Context-Sensitive Clustering Technique Based on Graph-Cut Initialization and Expectation-Maximization Algorithm     

Tyagi  M. Bovolo  F. Mehra  A.K. Chaudhuri  S. Bruzzone  L. 《Geoscience and Remote Sensing Letters, IEEE》2008,5(1):21-25

This letter presents a multistage clustering technique for unsupervised classification that is based on the following: 1) a graph-cut procedure to produce initial segments that are made up of pixels with similar spatial and spectral properties; 2) a fuzzy c-means algorithm to group these segments into a fixed number of classes; 3) a proper implementation of the expectation-maximization (EM) algorithm to estimate the statistical parameters of classes on the basis of the initial seeds that are achieved at convergence by the fuzzy c-means algorithm; and 4) the Bayes rule for minimum error to perform the final classification on the basis of the distributions that are estimated with the EM algorithm. Experimental results confirm the effectiveness of the proposed technique.  相似文献   

Impact of termite activity on soil environment: A perspective from their soluble chemical components     

K. Semhi Ph.D.  S. Chaudhuri Ph.D.  N. Clauer Ph.D.  J. L. Boeglin Ph.D. 《International Journal of Environmental Science and Technology》2008,5(4):431-444

An investigation on varied types of termite mounds relative to the nearby soils that are not inhabited by the termites in different places of Cameroon show that the activity of the termites is increasing the contents of most major and some trace elements in the termite mounds, except for Si and sometimes Fe, Mn, Na and K. These released elements are relocated into newly formed mineral phases that are dissolved by either H₂O or dilute HCl leachings. The Ca and Mn released by the termite activity testify for crystallization of Ca-Mg carbonates and phosphates as well as of Fe oxy-hydroxides and/or Mn hydroxides. Termite activity also induces an increase in the lanthanide contents, the mound materials being especially enriched in light lanthanides relative to the corresponding soils without termite activity. The shapes of the patterns support precipitation of Mn-Fe oxy-hydroxides and Ca carbonates-phosphates. The increased amounts of Eu and Ce linked to termite activity seem to relate to the occurrence of reducing agents that are released by the termites, modifying Eu⁺³ into Eu⁺² and Ce⁺⁴ into Ce⁺³, favoring in turn selective incorporation of Eu⁺² and Ce³⁺ in the new phases of the termite mounds. Another consequence of the termite activity is the precipitation of H₂O and HCl extractable phases having low Sr/Ca ratios. Even if the K/Rb values of the termite mounds are typical for common soil-forming silicate minerals, their relocation by an inorganic process alone does not explain an abnormally high ratio in the H₂O leachable mineral phases. It was also shown that the main source for K and Rb of the dissolved phases is not only the interlayer site of clay particles, but also nutrients immobilized in and by the termites.  相似文献   

Rare earth elements in Silurian pelitic schists from N.W. Maine     

Robert L Cullers  Long-Tsu Yeh  Sambhudas Chaudhuri  Charles V Guidotti 《Geochimica et cosmochimica acta》1974,38(3):389-400

Thirty-two samples of a series of metamorphosed Silurian (?) pelitic schists in the greenschist and amphibolite facies from N.W. Maine have been analyzed for their rare-earth element (REE) content. The REE contents of these samples do not change as a function of metamorphic grade. Two different metasedimentary formations have been sampled, and they differ significantly in their light REE content. The absolute and relative distribution of the REE in the Bangeley Formation are quite similar to the composites of N. American, European and Russian shales that have been determined thus far (e.g. median La/Lu ratio of the Bangeley Formation normalized to chondrites = 8.7 ± 3.0). Samples from the Perry Mt. Formation show large depletions in the light REE compared to the Bangeley Formation and previously analyzed shale and metamorphosed shale samples, but heavy REE concentrations that are quite similar to the other samples (e.g. median La/Lu ratio of the Perry Mt. normalized to chondrites = 1.2 ± 0.6). These differences in light REE content between the Perry Mt. Formation and other sedimentary rocks are probably due to differences in the original clay mineral compositions as modified by weathering and/or depositional environments.  相似文献   

Temporal variability in the withdrawal phase of southwest monsoon over India and related consequences in northeast monsoon: a climatological perspective     

Mondal  Paramita  Chaudhuri  Sutapa 《Theoretical and Applied Climatology》2022,148(3-4):1021-1034

Theoretical and Applied Climatology - The variability in duration of withdrawal phase of southwest monsoon over India is often witnessed to influence the northeast monsoon rainfall of India as...  相似文献   

Joint Pattern in Precambrian Rocks Around Galudih (India): Implications for Fold Mechanism     

Manish A. Mamtani  A. Ghosh  A.K. Chaudhuri  D. Sengupta 《Gondwana Research》2004,7(2):579-583

In this paper, analysis of joints developed in folded quartzites of Galudih area, Jharkhand State (India) is presented. The joint pattern indicates that NE–SW joints are the dominant set. These have developed perpendicular to the NW–SE trending axial planes and hinges of the folds in quartzites implying that they are cross-joints. Plumose structures are observed on NE–SW joint surfaces that indicate their formation by extension perpendicular to the joint face. It is inferred that this extension in NW-SE direction is related to NE–SW compressional stresses that resulted in folding of the quartzite by flexural-slip mechanism.  相似文献   

Torsion of a non-homogeneous solid of revolution     

Pranay Kumar Chaudhuri 《Pure and Applied Geophysics》1973,104(1):467-472

Summary Solution has been obtained in the case of torsion of a solid of revolution of non-homogeneous material. The problem of a twisted sphere has been deduced from the general solution. The effect of non-homogeneity has been illustrated graphically.  相似文献