Multi-element composition of soil, mosses and mushrooms and assessment of natural and artificial radioactivity of a pristine temperate rainforest system (Slavonia, Croatia)

This study investigates multi-element composition of soil, mosses and mushrooms from a pristine temperate rainforest (Prasnik, Croatia). Additionally, the activity levels of natural (238U, 235U and 232Th decay chains, 40K and 7Be) and anthropogenic (137Cs and 134Cs) radionuclides in the investigated soil samples, obtained by gamma spectrometry, provide baseline of environmental radioactivity levels in this area. The aim of investigation was to explore the uptake of metal(loid)s by bioindicator species (mosses, mushrooms) growing in a pristine environment characterized by naturally elevated concentration of metals. The calculated enrichment and bioaccumulation factors, correlations between different groups of elements and similar multi-element patterns in mosses, mushrooms and soil samples revealed the prevailing influence of the local substrate geochemistry on element concentrations in mosses and mushrooms. The results suggest atmospheric deposition of Bi, Cd and Pb, while radionuclide activities point to atmospheric fall-out (including global contamination by radiocaesium) and influence of the pedological substrate. The confined area of investigation, with limited variations in soil characteristics and geological composition, allowed clearer insight into the origin of metal(loid)s in mosses and mushrooms. On the other hand, using bioindicator species with different element uptake mechanisms enabled distinction between different sources of elements.