No abstract available

No abstract available

[en] More then thirty years long time series of groundwater levels, observed in 140 groundwater monitoring wells constituted the basis of the study in the area between the Danube and Tisza rivers (25000 km²), in Hungary. The changes of groundwater levels-above the first aquitard formation-are the result of different cumulative effects ( water infiltration from precipitation, water extraction etc.). Prior to time series analysis the hydro graphs of the studied area has been classified into six groups by cluster-analysis. Then it was possible to determine typical hydro graph patterns for the Danube-Tisza lnterfluves by taking group averages. On the other way round, regarding the years as variables and the wells as cases and again performing cluster-analysis years with similar groundwater behaviour could be grouped together. Turning to time series methods spectral analysis has been applied first. As the observation of the time series wasn't time-equidistant the Lomb-periodogram had to be used for calculating the length of periods. All time series exhibit an annual period. The five and eleven years period can be found in 90% and 50% of the time series respectively. Spectral analysis uses sinusoid waves to describe the time series in the frequency domain. But these waves extend to the full time scale, so it is essential that the periods prevail throughout the whole time interval of observations. Our conjecture was that this is not the case in our samples. Wavelet analysis had been carried out to approve this conjecture. This analysis showed that the annual period, so characteristic for the groundwater levels couldn't be significantly identified between the years 1971-1977 in 80% of the observed hydro graphs.(Author)

[en] Several researchers have examined and achieved favourable results in connection with the building industry's use of red mud extracted in large quantities from the processing of bauxite. These days more and more precedence is being given to limiting the radiological dose to the population. In this study carried out in Hungary, the use of red mud, bauxite, and clay additives recommended for the production of special cements, were examined from a radiological aspect. ²²⁶Ra and ²³²Th activity concentrations measured in Hungarian bauxite, red mud and clay samples were significantly similar with the levels for such raw materials mentioned in international literature. Taking radiation protection aspects into consideration, none of these products can be directly used for building construction. Taking Hungarian and international values into consideration, a small amount of red mud, not exceeding 15% could be used for brick production, for example as a colouring material. However, beyond this amount the standards for building materials would not be met. For the production of cements an even stricter limit needs to be determined when both bauxite and red mud are used