Dispersion and Mass Transfer in Groundwater Near-Surface Geologic Formations

2010 ◽  
pp. 413-451 ◽  
Author(s):  
Tissa Illangasekare ◽  
Christophe Frippiat ◽  
Radek Fuˇcík
Keyword(s):  
Mass Transfer ◽  
Near Surface

Kinetic Studies of Adsorption-Desorption of Cd and Zn Onto Al2O3/Solution Interfaces

1993 ◽  
Vol 28 (7) ◽  
pp. 39-45 ◽  
Author(s):  
K. S. L. Lo ◽  
J. O. Leckie
Keyword(s):  
Mass Transfer ◽  
Mass Transport ◽  
Metal Ion ◽  
Internal Diffusion ◽  
Internal Mass ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Near Surface ◽  
Film Diffusion ◽  
Slow Stage

The effects of external and internal mass transport limitations on zinc and cadmium adsorption onto the porous amorphous aluminium oxide/solution interfaces were studied. A modified two-stage rate model was used to interpret the experimental results. The rapid stage results from external surface film diffusion and internal diffusion into the near surface pores. The slow stage results from internal mass transport and extends over several days. The mass transfer-adsorption coefficients of the rapid stage are almost two orders of magnitude larger than those of the slow stage. The external mass transfer coefficients show an increasing trend with increasing pH, and appear to be affected by the charge/potential condition of the oxide/solution interface. The internal mass transfer coefficients indicate a uniform trend for both the zinc and cadmium results. The desorption rates and final metal ion solution concentrations are affected by the bulk solution pH. Film diffusion and internal diffusion are affected by the higher relative ratio of metal ion concentration to adsorbent concentration.

Mass Transfer and Concentration Contours around Surfaces Buried in Granular Beds and Exposed to Fluid Flow

2006 ◽  
Vol 258-260 ◽  
pp. 592-599
Author(s):  
João M.P.Q. Delgado ◽  
M.A. Alves ◽  
J.R.F.G Carvalho
Keyword(s):  
Mass Transfer ◽  
Fluid Flow ◽  
Numerical Solution ◽  
Cross Flow ◽  
Surface Concentration ◽  
Packed Bed ◽  
Soluble Solids ◽  
Spherical Particles ◽  
Near Surface ◽  
Flow Past

This work describes the process of mass transfer which takes place when a fluid flows past a soluble surface buried in a packed bed of small inert spherical particles of uniform voidage. The fluid is assumed to have uniform velocity far from the buried surface and different surface geometries are considered; namely, cylinder in cross flow and in flow aligned with the axis, flat surface aligned with the flow and sphere. The differential equations describing fluid flow and mass transfer by advection and diffusion in the interstices of the bed are presented and the method for obtaining their numerical solution is indicated. From the near surface concentration fields, given by the numerical solution, rates of mass transfer from the surface are computed and expressed in the form of a Sherwood number (Sh). The dependence between Sh and the Peclet number for flow past the surface is then established for each of the flow geometries. Finally, equations are derived for the concentration contour surfaces at a large distance from the soluble solids, by substituting the information obtained on mass transfer rates in the equation describing solute spreading in uniform flow past a point (or line) source.

scholarly journals Dynamics of Bubble Motion and Gas-Liquid Interfacial Phenomena

2003 ◽  
Author(s):  
Katsumi Tsuchiya
Keyword(s):  
Mass Transfer ◽  
Surface Wave ◽  
High Speed ◽  
Bubble Surface ◽  
Liquid Interface ◽  
Oscillatory Motion ◽  
Wave Formation ◽  
High Speed Imaging ◽  
Vertical Projection ◽  
Near Surface

Two aspects of the dynamics associated with oscillating bubbles are discussed in this paper: oscillatory motion of bubble itself and bubble-surface wave. The primary issue here is whether it is the case that the surface wave occurs in sychronization with the bubble’s oscillatory motion. The dynamic process of wave formation and propagation along the surface of an oscillating bubble is studied based on high-speed imaging, through which the wave characteristics such as wavelength and phase/propagation speed are evaluated as mostly the vertical projection of rather regularly generated bubble-surface ripples. The bubble oscillating motion is characterized quantitatively by the bubble-gyration (or edge-rotation) frequency, diameter and velocity. In addition, dynamics of mass transfer across gas–liquid interface in a gas-dispersed (continuous liquid) system are examined via high-sensitivity, high-speed imaging. The dispersive dynamics of the dissolved component from the gas into the liquid phase are visualized using laser-induced fluorescence (LIF) with pH-sensitive pyrene (HPTS) for both a single and multi-bubble systems. The coupling between these dynamics of surface/interfacial flow and mass transfer is attempted towards better understanding of such complex phenomena prevailing in the vicinity of the fluctuating gas–liquid interface. Enhancement of the mass transfer is found to be associated with the (nonlinear) wave formation, influence of which could be included in modeling the mass-transfer coefficient, apart from an physical account of the near-surface concentration gradient. Due to significant bubble–bubble interactions in a multi-bubble system, the dispersive pattern of low-pH region arising from gas dissolution becomes extremely complex; the visual estimate of time variation in fluorescence level is then mainly made over a fixed space in the gas–liquid flow system.

How did the Archean crust evolve? Insights from the structure and petrology of the Lewisian of Scotland

2021 ◽  
Author(s):  
Sophie Miocevich ◽  
Alex Copley ◽  
Owen Weller
Keyword(s):  
Mass Transfer ◽  
Central Region ◽  
Vertical Motion ◽  
Granulite Facies ◽  
High Grade ◽  
Near Surface ◽  
Granulite Facies Metamorphism ◽  
Dry Conditions ◽  
Archean Crust ◽  
Metamorphic Terranes

<p>High-grade Archean gneiss terranes expose mid to lower crustal rocks and are generally dominated by tonalite-trondhjemite-granodiorite (TTG) gneisses. Occurrences of mafic-ultramafic bodies and garnet-bearing felsic gneisses within these environments have been interpreted as supracrustal or near-surface rocks requiring a tectonic process involving mass transfer from the near-surface to the mid-crust. However, there is significant uncertainty regarding the nature of this mass transfer, with suggestions including a range of uniformitarian and non-uniformitarian scenarios.  One non-uniformitarian scenario, ‘sagduction’, has been proposed as a possible mechanism (Johnson <em>et al.,</em> 2016, and references therein), although the dynamics of sagduction are still relatively unexplored.</p><p>This study focuses on mafic, ultramafic and garnet-bearing felsic gneiss bodies in the central region in the Lewisian Gneiss Complex of northwest Scotland as test cases to investigate the behaviour of possibly supracrustal rocks in a mid-crustal environment. Existing datasets of TTGs (Johnson <em>et al.,</em> 2016), mafic gneisses (Feisel <em>et al.,</em> 2018) and ultramafic gneisses (Guice <em>et al.,</em> 2018) from across the central region were utilised in addition to felsic and mafic gneiss samples obtained in this study from the ~10 km<sup>2</sup> Cnoc an t-Sidhean (CAS) suite. The CAS suite is the largest reported supracrustal in the Lewisian, and dominantly comprises garnet-biotite felsic gneiss assemblages and an associated two-pyroxene mafic gneiss. Field mapping was undertaken to collect samples representative of the observed heterogeneity of the suite, and to assess field associations between possible supracrustals and surrounding TTGs. Phase equilibria modelling was conducted on all lithologies to ascertain peak pressure-temperature (<em>P-T</em>) conditions, and to calculate the density of the modelled rocks at peak conditions.</p><p>The results obtained in this study indicate peak metamorphic conditions of 950 ± 50 °C and 9 ± 1 kbar for the CAS suite, consistent with the central region of the Lewisian Complex (Feisel <em>et al.,</em> 2018). Density contrasts at mid-crustal conditions of 0.12–0.56 gcm<sup>-3</sup> were calculated between TTGs and the other lithologies and used to estimate the buoyancy force that drives density-driven segregation. This allowed us to investigate the rates of vertical motion that result from density contrasts, as a function of the effective viscosity during metamorphism. Independent viscosity estimates were attained using mineral flow-laws and our estimated <em>P-T</em> conditions, and from examination of modern-day regions of crustal flow. We were therefore able to estimate the conditions under which sagduction could have been a viable mechanism for crustal evolution in the Lewisian and similar high-grade metamorphic terranes. We conclude that sagduction was unlikely to have operated in the Lewisian under the dry conditions implied by preserved mineral assemblages.</p><p> </p><p> </p><p>Feisel, Y., et al. 2018. New constraints on granulite facies metamorphism and melt production in the Lewisian Complex, northwest Scotland. Journal of Metamorphic Geology. <strong>36</strong>, 799-819</p><p>Guice, G.L., et al. 2018. Assessing the Validity of Negative High Field Strength-Element Anomalies as a Proxy for Archaean Subduction: Evidence from the Ben Strome Complex, NW Scotland. Geosciences, <strong>8, </strong>338.</p><p>Johnson, T.E., et al. 2016. Subduction or sagduction? Ambiguity in constraining the origin of ultramafic–mafic bodies in the Archean crust of NW Scotland. Precambrian Research, <strong>283</strong>, 89-105.</p>

Determination of a Mass Transfer Area during Metal Melting in a Vacuum Induction Furnace

2014 ◽  
Vol 59 (1) ◽  
pp. 287-292 ◽  
Author(s):  
S. Golak ◽  
R. Przylucki ◽  
J. Barglik
Keyword(s):  
Mass Transfer ◽  
Liquid Steel ◽  
Induction Furnace ◽  
Surface Velocity ◽  
Vacuum Induction Furnace ◽  
Near Surface ◽  
Actual Surface ◽  
Calculation Results ◽  
Metal Melting

Abstract In the paper, a simulation model that allows for determination of the actual surface area of inductively stirred liquid metal and the value of metal near-surface velocity during its melting is presented. Also, the effects of induction furnace working frequency on both parameters are demonstrated. The simulation was performed for copper and liquid steel that were melted in two different induction furnaces. The calculation results were also used for determination of coefficients of copper mass transfer in liquid steel and of antimony mass transfer in liquid copper during their stirring in the discussed furnace.

Fundamental Study on Transport Model for Radionuclides under Unsaturated Condition around Near-Surface Underground

MRS Advances ◽  
2020 ◽  
Vol 5 (5-6) ◽  
pp. 223-232
Author(s):  
Takenori Ozutsumi ◽  
Masayuki Kogure ◽  
Yuichi Niibori ◽  
Taiji Chida
Keyword(s):  
Mass Transfer ◽  
Unsaturated Zone ◽  
Transport Model ◽  
Path Model ◽  
Local Flow ◽  
Near Surface ◽  
One Dimensional ◽  
Retardation Coefficient ◽  
The One ◽  
Unsaturated Condition

ABSTRACTThe low-level nuclear wastes such as decontamination waste from Fukushima are disposed in near-surface underground, where the intermittent recharge of rain and groundwater causes spatial distribution of water content. Therefore, pores of soils are not filled with water, that is, an unsaturated zone will be formed. In such a condition, since the water flow path are detoured by clogged gas in pores of soil in the unsaturated zone, the migration path of radionuclide would be different from the saturated zone. So far, the one-dimensional advection-dispersion equation (ADE) model has been widely used in order to explain experimental results under an unsaturated condition. However, the detouring of local flow-paths remarkably affects the mass transfer. The one-dimensional ADE evaluates such a detouring effect by using Peclet number and retardation coefficient as fitting parameters. In other words, the one-dimensional ADE model is difficult to explain mass transfer under an unsaturated condition. Therefore, the purpose of this study is explaining such complicated transport of radionuclides using a multi-path model based on phenomena in underground. The proposed multi-path model considering both water saturation and permeability distributions showed good agreement with the experimental data under an unsaturated condition.

scholarly journals Influence of climate variability on water partitioning and effective energy and mass transfer in a semi-arid critical zone

2016 ◽  
Vol 20 (3) ◽  
pp. 1103-1115 ◽  
Author(s):  
Xavier Zapata-Rios ◽  
Paul D. Brooks ◽  
Peter A. Troch ◽  
Jennifer McIntosh ◽  
Craig Rasmussen
Keyword(s):  
Mass Transfer ◽  
Climate Variability ◽  
Water Availability ◽  
Temporal Trends ◽  
Critical Zone ◽  
Ecosystem Structure ◽  
Effective Energy ◽  
Upward Migration ◽  
Near Surface ◽  
Decadal Scale

Abstract. The critical zone (CZ) is the heterogeneous, near-surface layer of the planet that regulates life-sustaining resources. Previous research has demonstrated that a quantification of the influxes of effective energy and mass transfer (EEMT) to the CZ can predict its structure and function. In this study, we quantify how climate variability in the last 3 decades (1984–2012) has affected water availability and the temporal trends in EEMT. This study takes place in the 1200 km2 upper Jemez River basin in northern New Mexico. The analysis of climate, water availability, and EEMT was based on records from two high-elevation SNOTEL stations, PRISM data, catchment-scale discharge, and satellite-derived net primary productivity (MODIS). Results from this study indicated a decreasing trend in water availability, a reduction in forest productivity (4 g C m−2 per 10 mm of reduction in precipitation), and decreasing EEMT (1.2–1.3 MJ m2 decade−1). Although we do not know the timescales of CZ change, these results suggest an upward migration of CZ/ecosystem structure on the order of 100 m decade−1, and that decadal-scale differences in EEMT are similar to the differences between convergent/hydrologically subsidized and planar/divergent landscapes, which have been shown to be very different in vegetation and CZ structure.

Optical Doppler tomography of near-surface mass transfer processes induced by femtosecond laser

2001 ◽  
Author(s):  
Kirill P. Bestemyanov ◽  
Vyacheslav M. Gordienko ◽  
Alexei Konovalov ◽  
S. A. Magnitskii ◽  
J. S. Toursunov
Keyword(s):  
Mass Transfer ◽  
Femtosecond Laser ◽  
Doppler Tomography ◽  
Near Surface ◽  
Surface Mass ◽  
Transfer Processes ◽  
Surface Mass Transfer ◽  
Mass Transfer Processes ◽  
Optical Doppler Tomography

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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