DETERMINATION OF THE VERTICAL DISTRIBUTION OF^ 226Ra, ^232Th, ^40К AND ^137Cs IN SAMPLES OF CULTIVATED SOIL TAKEN IN THE VICINITY OF CERTAIN CITIES IN REPUBLIC OF MACEDONIA

The purpose of this research was focused on determination of the concentrations of activity of ^226Ra, ^232Th, ^40К and ^137Cs in the soil samples collected from cultivated soil close to several larger cities in the Republic of Macedonia (Tetovo, Veles, Bitola) by using gamma spectrometry. Data show that the average value of activity of ^226Ra and ^232Th are within the range of (25.58- 36.48) and (36.55-50.45) Bq kg^-1, respectively. While, the concentrations of activity of 40К in comparison to those obtained for ^232Th and ^226Ra are higher in all analyzed soils samples, showing values within the range of (611.59-781.23) Bq kg^-1, the activities of ^137Cs are generally lower and are within the range of (9.33-18.90) Bq kg^-1, with the highest activity at a depth of 5 cm, which is well in accordance with the data from the literature. However, ^40К is the only radionuclide which was determined with a significant quantity in the soil samples, and for which one can tell that in all locations at a depth to 5 cm it shows highest level of activity. It is considered that all other determined radionuclides which occur naturally, have nominal concentrations. On the basis of the obtained results so far, we can conclude that the soil samples which have been collected in the environment of the observed cities, do not indicate increased radioactivity, which could impose a threat for the food production that might have negative influence on human’s health. The concentrations of these radionuclides are comparable to the available data from the other countries.