Variation of 40K, 238U and 232Th specific activities in soil within geological units of Republic of Macedonia

Stojanovska, Zdenka and Boev, Blazo and Ristova, Mimoza and Dimov, Gorgi (2017) Variation of 40K, 238U and 232Th specific activities in soil within geological units of Republic of Macedonia. In: INSINUME 2017 - 7th International Symposium on IN SItu NUclear MEtrology as a tool for radioecology, 24–28 April 2017, Ohrid,Republic of Macedonia. (Unpublished)

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Abstract

Territory of Republic of Macedonia (situated on 25.713 km2) is roughly divisible in four geotectonic units: Western Macedonian Zone (WMZ), Pelagonian Massif (PM), Vardar Zone (VZ) and Serbo-Macedonian Massif (SMM) and one separate volcanic area: Kratovsko-Zletovska Area (KZA). In order to establish relation between terrestrial radioactivity in populated areas and the aforementioned geologically determined regions of the country, a total number of 200 soil samples from 20 cm depth were collected from regions around the major settlements and cities evenly from all the geotectonic units. After their standard preparation, the samples were subjected to high-resolution gamma spectrometry.
The results of the analysis of the variance showed statistically significant differences among the specific activities (A) of 40K, 238U and 232Th measured from soils of different geotectonic units. The following geometric mean (GM) values and geometric standard deviations (GSD) of (40K), A(238U) and A(232Th) were obtained: 627 Bq/kg (1.38), 41 Bq/kg (1.44) and 40 Bq/kg (1.37) for WMZ; 620 Bq/kg (1.33), 52 Bq/kg (1.41) and 55 Bq/kg (1.42) for PM; 464 Bq/kg (1.51), 30 Bq/kg (1.48) and 30 Bq/kg (1.52) for VZ; 635 Bq/kg (1.36), 44 Bq/kg (1.44) and 41 Bq/kg (1.44) for SMM; 621 Bq/kg (1.25), 56 Bq/kg (1.22) and 51 Bq/kg (1.15) for KZA. Further analysis confirmed that these differences are related to the type of the rocks from which soils originate, and hence to the geological composition of each lithological area. Pairwise Comparison activity analysis of the three radionuclides, resulted in grouping of the soils into two major groups: the first one to be soils of volcanic origin, and the second one to be soils of metamorphic and sedimentary origin. It appeared that the GM values of A(40K) = 702 Bq/kg (1.27), A(238U) = 59 Bq/kg (1.32) and A(232Th) = 59 Bq/kg (1.42) in soil with volcanic origin were higher than activities in soils originating from metamorphic: A(40K) = 567 Bq/kg (1.56), A(238U) = 39 Bq/kg (1.47) and A(232Th) = 41 Bq/kg (1.46) and sedimentary A(40K) = 530 Bq/kg (1.45), A(238U) = 36 Bq/kg (1.52) and A(232Th) = 35 Bq/kg (1.52) rocks. Furthermore, the soils results were classified by lithostratigraphic units (23 samples for this study). It also appeared that they show a grouping tendency. According to the differences among A(40K), A(238U) and A(232Th) in the different lithostratigraphic units, the results were grouped into four groups.

Item Type: Conference or Workshop Item (Poster)
Subjects: Natural sciences > Physical sciences
Divisions: Faculty of Medical Science
Depositing User: Zdenka Stojanovska
Date Deposited: 27 Jun 2017 10:12
Last Modified: 27 Jun 2017 10:12
URI: https://eprints.ugd.edu.mk/id/eprint/17943

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