[en] The purpose of this project is to determine oil-and water saturations in a core plug, and to make this determination two dimentional. By grouping a series of two dimentional sections together, it would be possible to obtain a primitive three dimentional view of the liquid saturations in the plug. The idea behind the project is to provide a relatively cheap alternative to the existing NMR-and CT scanning methods. This reduction in cost is obtained at the price of a reduced spatial resolution

[en] Significant amounts of fallout ¹³⁷Cs from nuclear weapons tests were introduced to the landscape during the 1950s and 1960s. Once ¹³⁷Cs reaches the soil surface it is strongly and quickly adsorbed by clay particles, and is essentially nonexchangeable in most environments. Thus, ¹³⁷Cs becomes and effective tracer of the movement of soil particles across the landscape. Over the past 30 years, researchers have shown that ¹³⁷Cs can be used to study soil movement. Early work used empirical relationships between soil loss and ¹³⁷Cs loss to estimate erosion. This was followed by the development of proportional and theoretical models to relate ¹³⁷Cs movement and soil redistribution. Most of the problems related to the ¹³⁷Cs technique are the same as those encountered with other techniques (i.e., sampling, measurement). The ¹³⁷Cs technique can make actual measurements of soil loss and redeposition in fields, fostering the formulation of better plans to conserve the quality of the landscape. This paper reviews the development of the ¹³⁷Cs technique to show how it can be used to understand erosion and soil movement on the landscape. (author)

[en] Speciation of minor or trace amount of pollutants, such as heavy metals and radionuclides released from atmospheric precipitation and water streams have been studied in order to elucidate their fates in the environment through 'in situ' observations or laboratory experiments. The authors have investigated sorption of heavy metals on various natural samples radiometrically (⁶⁵Zn as a tracer). A sequential extraction technique was found to be very effective to elucidate possible scavengers (minerals) of heavy metals in some cases. A sediment with low CEC does not sorb Zn (ii) ions to a great extent. It is thus considered that the zinc sorption occurs competitively with protons present in the aqueous media. Divalent copper and cadmium ions also behaved similarly to Zn(II), which was obtained electrochemically with the ion selective electrodes of Cu(II) and Cd(II). This time the authors investigated the competitive sorption of Mn(ii) and Zn(II) to natural soils using a radiotracer technique, which was considered to be useful to evaluate relative importance of the sorption of each metal ion without serious matrix effects. Quite different properties appeared among those metal ions used independently or simultaneously as a tracer. Proton exchange process may be important for the Zn(II) sorption, whereas a solid-solution partition is supposed to control the Mn(ii) uptake, when each of them was examined independently as a sorbate. In contrast, simultaneous use of those tracers to a soil suspension had great effects on the result; the maximum sorption (A_m) of Zn(II) increased, and Mn(II) behaved like a sorbate which tends to occupy specific sites of the soil surfaces. Those results indicate that the sorption of minor and/or trace elements to natural soils would not be evaluated through a series of experiments with a single sorbate

[en] Full text: In the absence of direct evidence for burial and subsequent exposure of the land surface in the interior of Africa, researchers have argued for surface ages of several hundred million years. The proposition that landforms may have persisted at the surface for these extensive periods of time has a number of important implications. It suggests that the processes of tectonics and geomorphic evolution have been essentially absent for a period of up to 500 Ma. As a consequence, the persistence of these landscapes would require extremely low rates of weathering and erosion. Although this view of continental evolution has been widely held for several decades, recent studies suggest that continental interiors in Africa, Australia, Brazil and north America, have been subject to denudation in the order of several kilometres during the last 60 Ma. This study applies the complimentary techniques of apatite fission track and cosmogenic nuclide analysis, in an effort to measure both the long-term crustal-scale denudation and the short-term erosion rates, of which denudation is a function. We present preliminary data from the Zimbabwe Craton that illustrates the utility of such techniques in addressing both local and regional geological questions. The study provides a detailed picture of complex tectonic responses as well as large scale denudation over extended periods of time

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[en] Recent studies have confirmed that CFC's can be used as a tool for dating ground water. The basic assumption is that the concentrations of CFC's in a particular water mass are at equilibrium with the CFCs partial pressures in the atmosphere at the time when the water reaches the ground water table and is further on isolated from the atmosphere. The analysis is easy, inexpensive and rapid; CFCs are a very sensitive indicators to contamination of ground water by modern surface waters