Effects of physical-chemical properties of soils on 60Co and 65Zn bioavailability

Abstract

The purposes of the paper are to estimate the inactivating power of soils in relation to radiologically important long-lived radionuclides 65Zn and 60Co and to develop methodological approaches for assessing effects of edaphic factors on the radionuclides mobility in the soil-plant system. For the experimental studies, different soil samples were collected (16 soil types, classes, and subclasses). A model experiment was carried out in a greenhouse where barley plants were grown under controlled conditions for 2 weeks on soils artificially contaminated by 65ZnCl2 and 60CoCl2. The biological availability of stable “natural” Zn, which is an aggregate of stable nuclides, radionuclides 65Zn and 60Co, was determined using the concentration ratio (CR). The physical and chemical parameters of soil (pH, the sum of silt, and clay particles (<0.01 mm) content, Fe mobile, P mobile, humus content, a ratio of humic and fulvic acid carbon (CHA/CFA), contents of mobile forms of elements (Co, Zn)) were determined. Experimental data were subjected to statistical analysis. An effort has been made to quantify the relationships between the parameters describing physical-chemical properties of soils and those that characterize 65Zn and 60Co bioavailability. A methodological approach has been used, which employs natural diversity of physical-chemical properties of different types and kinds of noncarbonate and carbonate soils in the European part of Russia, to find relevant relationships. The use of radioactive isotopes of trace elements provides an opportunity to predict the behavior of the technogenous origin metals in the soil-plant system. Methodological approach for estimation of soil characteristic contribution to common inactivating capacity in relation to radionuclide migration in the soil-plant system was suggested. On its basis, a scale of soil inactivating capacity can be developed. The derived results allow ranking of the selected physical-chemical parameters of soils by their influence on CR (65Zn or 60Co) value in barley.