The importance of second order activation in the determination of trace elements in geological samples by instrumental neutron activation analysis

This paper deals with the disturbance of INAA trace element determinations in rocks by second order activation. The degree of error in the determination of Gd by Eu in rocks is checked by experiments and compared with results of computer evaluations. The consequence of the Dy-interference for the determination of Ho was also calculated. Hints to avoid these interferences are given.     

TRANSFORMATION OF DIPOLE TO SCHLUMBERGER SOUNDING CURVES BY MEANS OF DIGITAL LINEAR FILTERS*

Linear relationship between dipole and Schlumberger sounding resistivities leads to the use of digital filters to transform the former to the latter. This transformation is of importance from the viewpoint that Schlumberger interpretational techniques and know-how could then be applied to the pseudo-Schlumberger field curve. Filters for this transformation are presented for the radial, perpendicular, and parallel (30°) dipole method. The characteristics of these filters are similar to the ones for transforming dipole data to the kernel and are favourable in that they do not amplify noise. A sampling interval of (In 10) /6 has been used in determining the filter yielding good accuracy. Like previous filters the present one is handy and fast in operation.     

Convection in a variable-viscosity fluid: Newtonian versus power-law rheology

A number of finite-element calculations of convection in a variable-viscosity fluid have been carried out to investigate the effects of non-Newtonian flow when rheology is also subject to a strong temperature and pressure influence. A variety of cases has been studied in the range of effective Rayleigh numbers between 10⁴ and 10⁶, including different modes of heating and a range of values for activation energy and activation volume. Power-law creep with a stress exponent of 3 turns out to lead to considerably different flow pattern and heat transfer properties than Newtonian rheology. In general, the effect is to reduce viscosity contrasts imposed by p,T dependence, which can lead in some circumstances to the mobilisation of otherwise stagnant regions within the cell. The properties of non-Newtonian flow can be closely imitated by a Newtonian fluid with a reduced value of the activation enthalpy bH^* with b?0.3–0.5. It appears possible that non-Newtonian rheology plays a key role in determining the convective style in a planetary mantle.     

Zum Zusammenhang von Parametern der Wassermengen und Wasserbeschaffenheit

By means of the quality criteria COD-Mn, NO₃^?, substances which can be filtered off and components of phosphate at two measuring stations at the river Elbe in the section of Dresden as well as an inflow gauge at a drinking water reservoir in the Eastern Ore Mountains there were investigated correlative connections with hydrological and meteorological quantities. Statistically secured connections between matter-balance and water-balance components were recorded on the basis of regression statements. The large number of the factors to be observed in the development of process-describing matter discharge models is determined by the large number of “causing or influencing quantities”. With respect to continuing investigations, it is recommended to take into account the dynamic character of precipitation and the influence of vegetation more exactly, especially in the case of substance components carried away from areas, as substances which can be filtered off, nitrate, o-phosphate.     

Bioindikation zur Verminderung von Stickstoffdüngerverlusten und der Stickstoffbelastung von Gewässern

Prerequisite to the nitrogen leaching from agricultural soils in spring is the ecologically optimum control of the first nitrogen fertilizer application. On the basis of investigations having been carried out for some years, a method for determining the optimum time of fertilization with the aid of phenological data is presented. The blossoming data of Anemone nemorosa proved to be a suitable sensitive indicator, their onset of blossoming is the optimum time for the first nitrogen application. In dependence on the height and variation of weather, in the subdued mountains this time is 90 … 116 d after the beginning of the year and corresponds to a temperaturetotal ≥ 5°C of 80 … 120°C or > 0°C: 160 … 230°C. Possibly, the leaf development of Alchemilla vulgaris or the first development of Poa pratensis are suitable as other bioindicators. The boundary conditions and disturbance variables of the bioindication are discussed. By the phenological date-determination of the beginning of fertilization the nitrogen losses can be reduced by 10 … 20% and the nitrate leaching can be considerably reduced especially in drinking-water protection areas.     

Age dependence of continental heat flow—fantasy and facts

Extensive use of empirical heat flow/age relations in the field of thermal studies indicates that the basic concept of a relation between heat flow and age is deeply entrenched. The idea of a thermal time constant and thermal thickness for the lithosphere depends on the validity of a heat flow/age relation. Several thermal and thermo-mechanical lithospheric models are constrained by a heat flow/age relation, a corrected heat flow/age relation, or a reduced heat flow/age relation. The theory of plate tectonics provides a physical basis for a heat flow/age relation for the oceans. Reliable heat flow measurements from well-sedimented areas of the oceans are known to support it. On the contrary, the theory of plate tectonics does not support an age relation for the continents, which is not well realized. It is pointed out that according to the theory of plate tectonics, a distinct heat flow profile should characterize a Cenozoic/Mesozoic orogenic belt over the continents, and a variety of profiles could be expected on account of several possible interactions at convergent plate boundaries. A specific characteristic heat flow value corresponding to a particular age loses meaning, and therefore a heat flow/age relation (or curve) becomes conceptually invalid. Presently available continental heat flow data, statistically analysed in a proper manner, do not (as they should not) support an age relation. Attempts at correcting age-dependent heat flow means for crustal radiogenic heat to obtain an age relation for mantle heat flow do not yield meaningful results.