Depth profiling general equation

Equation (9) is quite generalized and allows for variations in the mixing rate, K, and in situ density, p, with depth in determining the activity-time relationship of radionuclide profiles. However, in all commonly used models, equation (9) is further simplified using assumptions such as K, p and S to be... 

From a more general standpoint, if we consider a polyphase sample with a concentration gradient that extends over a depth of a few tens of micrometers, then X-ray diffraction at a fixed incidence can be used for producing concentration profiles based on measnrements of diffracted intensities. Quantitatively determining concentrations leqnires accurately taking into account the irradiated volumes. Relations inferred from the equations given in section 2.3.1.2 have been laid out and are nowadays relatively often used [SCA 93]. 

It is not to be expected that the straight-line Equation 21 would apply to the thermocline layers of other lakes. Both N and K were calculated from temperature profiles the shape of which depends in a complex manner on the climate of the area, thermal regime, depth, and volume of the lake. It seems, however, that by arguments presented earlier in this section, an inverse relationship between the stability frequency and eddy diffusion coefficient would, in general, hold in the pycnocline layers of lakes. If such a relationship is established, it would be possible to obtain estimates of K from the values of the stability frequency N, which are much easier to compute. 

The two stations located approximately on the equator also contain the same water masses as the southern station. Unfortunately, the distribution of samples was not suflBcient to have a complete collection of representative samples. Only one depth of the Antarctic intermediate water was sampled and the Antarctic bottom water was not sampled at all at these stations and a comparison between Antarctic bottom water at these stations and that at the southern station, unfortunately is not possible. The data that are available, nevertheless, show that at 00°08 N 32°32 W, the observed variation is much larger than at corresponding depths in the southern station at 05°01 S 32°34 W and generally indicates a lower value for the ratio in the upper 75 meters. There is no agreement observed between the two profiles at a depth of about 300 meters, a depth where an increasing oxygen concentration with depth occurs. However, the value of the ratio for the northerly flowing Antarctic intermediate water at 450 meters is comparable with that at the southerly... 

An equation for the mixing of a tracer associated with the solid phase in a sediment profile is derived from the general diagenic equation (Berner, 1980). For a radioactive tracer with steady-state conditions and where bed porosity changes with depth can be considered negligible, the defining equation is the familiar equation of advective-diffusive transport ... 

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