A method of calculating quartz solubilities in aqueous sodium chloride solutions   总被引：1，自引：0，他引：1  

Robert O. Fournier 《Geochimica et cosmochimica acta》1983,47(3):579-586

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm³ of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, p_e, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na⁺ as water of hydration. Generally, the hydration of water correction is negligible.The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting p_e, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H₂. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water.The average hydration number per molecule of dissolved SiO₂ in liquid water and NaCl solutions decreases from about 2.4 at 200°C to about 2.1 at 350°C. This suggests that H₄SiO₄ may be the dominant aqueous silica species at 350°C, but other polymeric forms become important at lower temperatures.  相似文献   

Field measurements of snow-drift threshold and mass fluxes,and related model simulations   总被引：2，自引：2，他引：0  

Judith?J.?JDoorschot  Michael?LehningEmail author  Anouck?Vrouwe 《Boundary-Layer Meteorology》2004,113(3):347-368

Field measurements were carried out to calculate the threshold friction velocity for snow saltation, and mass fluxes during snow drift. The wind was measured in three components by an ultrasonic anemometer, and the mass fluxes were determined using an optical sensor (snow particle counter), acoustic sensors (Flowcapt) and mechanical traps. The threshold friction velocity was found to be correlated to the grain size (R²=0.75). The mass flux measurements were compared with numerical simulations of snow drift, and it was demonstrated that the maximum snow transport takes place at shear stress values of roughly two times the average shear stress over 20 min. By implementing a probability distribution for the shear stress the mass flux was simulated with only the mean measured value of the shear stress as input. This procedure enables the future use of the numerical model for operational applications.  相似文献   

Aerobic, co-metabolic in situ biodegradation of chlorinated solvents and horizontal biosparge wells--a match made in bioremediation heaven   总被引：1，自引：0，他引：1  

Fournier LB 《Ground water》2003,41(6):727-728

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Application of the spectral-element method to the axisymmetric Navier–Stokes equation     

A. Fournier  H.-P. Bunge  R. Hollerbach  J.-P. Vilotte 《Geophysical Journal International》2004,156(3):682-700

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Assessing the Goodness-of-Fit of Statistical Distributions When Data Are Grouped     

Judith K. Haschenburger  John J. Spinelli 《Mathematical Geology》2005,37(3):261-276

Modeling statistical distributions of phenomena can be compromised by the choice of goodness-of-fit statistics. The Pearson chi-square test is the most commonly used test in the geosciences, but the lesser known empirical distribution function (EDF) statistics should be preferred in many test situations. Using a data set from geomorphology, the Anderson–Darling test for grouped exponential distributions is employed to illustrate ease of use and statistical advantages of this EDF test. Attention to the issues discussed will result in more informed statistic selection and increased rigor in the identification of distribution functions that describe random variables.  相似文献   

Mapping Curvilinear Structures with Local Anisotropy Kriging     

Chris B. M. te Stroet  Judith J. J. C. Snepvangers 《Mathematical Geology》2005,37(6):635-649

Interpolating geo-data with curvilinear structures using geostatistics is often disappointing. Channels, for example, become disconnected sets of lakes when interpolated from point data. In order to improve the interpolation of geological structures (e.g., curvilinear structures), we present a new form of kriging, local anisotropy kriging (LAK). Local anisotropy kriging combines a gradient algorithm from image analysis with kriging in an iterative way. After an initial standard kriging interpolation, the gradient algorithm determines the local anisotropy for each cell in the grid using a search area around the cell. Subsequently, kriging is carried out with the spatially varying anisotropy. The anisotropy calculation and subsequent kriging steps will then succeed until the result is satisfactory in the way of reproducing the curvilinear structures. Depending on the size of the search area more or less detail in the geological structures can be reproduced with LAK. Using test examples we show that LAK interpolates data with curvilinear structures more realistically than standard kriging. In a real world case, using bathymetric data of the Oosterschelde estuary, LAK also proves to be quantitatively superior to standard kriging. Absolute interpolation errors are decreased by 23%. Local anisotropy kriging only uses information from point data, which makes the method very objective, it only presents “what the data can tell.”  相似文献   

15,000 Years of mass-movement history in Lake Lucerne: Implications for seismic and tsunami hazards   总被引：2，自引：0，他引：2  

Michael Schnellmann  Flavio S. Anselmetti  Domenico Giardini  Judith A. Mckenzie 《Eclogae Geologicae Helvetiae》2006,99(3):409-428

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Statement by Incoming Editors     

Peter Homewood  Philip Allen  Judith McKENZIE 《Sedimentology》1987,34(1):1-1

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Effects of tributyltin on activity and burrowing behavior of the fiddler crab,Uca pugilator     

Judith S. Weis  James Perlmutter 《Estuaries and Coasts》1987,10(4):342-346

Fiddler crabs,Uca pugilator, collected from the field showed no avoidance to burrowing in 1 μg g^?1 tributyltin (TBT)-contaminated sand held in laboratory trays. Treatment ofU. pugilator with levels of tributyltin as low as 0.5 μg l^?1 for 1–3 wk resulted in an acceleration of the righting reflex in females, indicative of hyperactivity. Crabs of both sexes exhibited a reduction in burrowing activity, as measured by the number of burrows dug at 15 and 60 min after release into laboratory trays containing sand, and by the number of crabs within burrows at those times. The reduction in burrowing activity was not dose-dependent at concentrations of 0.5 to 50 μg l^?1, and was unchanged between one and three weeks of exposure. Since fiddler crabs are dependent on burrows for many aspects of their lives, the reduction in burrowing behavior, should it occur in nature, would have serious consequences for the species.  相似文献   

Astronomical imaging with InSb arrays     

Judith L. Pipher 《Experimental Astronomy》1994,3(1-4):1-8

Ten years ago, Forrest presented the first astronomical images with an SBRC 32×32 InSb array camera at the first NASA-Ames Infrared Detector Technology Workshop. Soon after, SBRC began development of 58×62 InSb arrays, both for ground-based astronomy and for SIRTF. By the time of the 1987 Hilo workshop Ground-based Astronomical Observations with Infrared Array Detectors astronomical results from cameras based on SBRC 32×32 and 58×62 InSb arrays, a CE linear InSb array, and a French 32×32 InSb CID array were presented. And at the Tucson 1990 meeting Astrophysics with Infrared Arrays, it was clear that this new technology was no longer the province of IR pundits, but provided a tool for all astronomers. At this meeting, the first astronomical observations with SBRC's new, gateless passivation 256×256 InSb arrays will be presented: they perform spectacularly!In this review, I can only broadly brush on the interesting science completed with InSb array cameras. Because of the broad wavelength coverage (1–5.5 m) of InSb, and the extremely high performance levels throughout the band, InSb cameras are used not only in the near IR, but also from 3–5.5 m, where unique science is achieved. For example, the point-like central engines of AGNs are delineated at L and M, and Br and 3.29 m dust emission images of galactic and extragalactic objects yield excitation conditions. Examples of imaging spectroscopy, high spatial resolution imaging, as well as deep, broad-band imaging with InSb cameras at this meeting illustrate the power of InSb array cameras.  相似文献