Оцінювання вмісту 90Sr у деревині сосни звичайної на основі вимірювання щільності потоку бета-частинок із поверхні кори стовбура

Abstract

This paper presents an approach for indirect measuring of 90Sr activity concentration in stem wood of Scots pine`s live trees within the Chernobyl exclusion zone based on values of beta-particles surface flux density from stem bark at a thee height of 1.3 m above the forest floor that obtained by use STORA-TU RKS-01 radiometer-dosimeter under field condition. The similar express-methods often consider in scientific publications so as they allow to obtain probable levels of radiation contamination without taking samples for laboratory measurements. That in turn can be used to optimize sampling or for example in the case of the need to preserve the intact initial state of the biota during long-term in situ or/and in vivo observations. The empirical data for validation of the method have received on 13 experimental sites of artificial (plantation) even-aged stands which consist only of one woody species: Scots pine. The correlation analysis discovered statistical significant relation at p-value=0.05 between arithmetic averages of beta-particles surface flux density from stem bark of pine trees at the forest sites and 90Sr activity concentration in stem wood elements (sap wood, heartwood and all stem wood), and functional dependencies among these parameters are described by a simple linear equation with only one slope parameters (R2 = 0.90–0.96) whose predicted values for sap wood, heartwood, and all stem wood are (± standard deviation) 23.1±8.5, 42.3±10.3, and 26.8±6.8 Bq·cm2·min·(kg·pcs)-1, respectively. Moreover, the influence of biometric indicators of individual trees (diameter, height, age) on this pattern was not detected. However, the average diameter (DBH) of stands has the strongest influence among forest inventory indicators on the value of the 90Sr activity concentration ratio between sap wood and heartwood (r = 0.93), that is, the radial distribution of the studied radionuclide in stem wood of pine trees. The results of these studies should be confirmed by a larger collection of observations for Scots pine given the small sample size for her in this paper. Also, scientists are necessary to include empirical data for other major forest-forming woody species within the research region due to the importance of using express-methods of radioactive contamination levels estimation for the planning and optimization of forest management.