Solutions tracers

For nuclei that are coherent with the surrounding crystal, the lattice is continuous across the a//3 interface. The jumps controlling the /3C frequency factor will then be essentially matrix-crystal jumps and /3C will be equal to the product of the number of solute atoms surrounding the nucleus in the matrix, zcXg, and the solute atom jump rate, T, in the a crystal. The jump frequency can reasonably be approximated by T Di/a2 (see Eq. 7.52, where D is the solute tracer diffusivity and a is the jump distance). Therefore,... 

Groundwater-inflow rates as calculated by the solute and isotope mass-balance methods for several northern Wisconsin lakes are listed in Table I. Dissolved calcium was used as the solute tracer because it is the constituent whose concentration differs the most between groundwater and precipitation, the two input components to be separated by the method. In addition, calcium is nearly conservative in the soft-water, moderately acidic to cir-cum-neutral lakes in northern Wisconsin. Results from the two methods agree relatively well, except for Crystal Lake, where groundwater-flow reversals are frequent. 

The isotope mass-balance method is not as useful for estimating groundwater-flow rates for groundwater-poor lakes as it is for lakes that receive substantial quantities of groundwater. Solute tracers, such as dissolved calcium, may be useful in assessing... 

Tracer Solutions. Tracer solutions were prepared by using aliquots of stock solutions of the tracer and evaporating them... 

Solute (tracer) Material (metal. crystalline form and purity) Temperature range. C Form of analysis Activation energy. Q. Kcal mole Frequency factor. 0(,. cm sec Refercn... 

Solute (tracer) crystalline Temperature Form of energy. Q. factor. Do. Reference... 

In tracer diffusion, however, where the attention is focused upon individual solute molecules that are labeled in some manner, molecular interactions between solvent and tracer, solvent and unlabeled solute, and tracer and unlabeled solute will all contribute to the observed rate of tracer diffusion. Tracer diffusion can be analyzed by considering a ternary system solvent, solute (A), and labeled solute (tracer. A ). The molar fluxes of the individual solute species can be written directly from Equation 4-13 ... 

In concentrated solution, tracer diffusion is a much more complex process which may not provide coefficients identical with those in the binary system. This is illustrated by the data in Fig. 7.5-1. In this figure, we see that the diffusion coefficients using different radioactive isotopes can differ from each other and from the binary diffusion coefficient. On reflection, we realize that this is not surprising the diffusion of radioactively tagged benzene in un tagged benzene is obviously a different process than the diffusion of tagged cyclohexane in benzene. 

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