Edible and medicinal macrofungi used in human diet represent not only important sources of nutritive elements but toxic substances as well (heavy metals and radionuclides). Radioactivity levels of four radionuclides ((40)K, (137)Cs, (226)Ra, (228)Ra) were determined in the basidiomata (fruiting bodies of a Basidiomycetes) of six lignicolous (Fomitopsis pinicola, Ganoderma applanatum, Hericium clathroides, Megacollybia platyphylla, Pluteus cervinus, Trametes gibbosa) and three mycorrhizal (Boletus luridus, Boletus sp. 1, Boletus sp. 2) species as well as their soil (wood) substrates by gamma spectrometry (high-resolution high-purity germanium (HPGe) detector). The aim was to investigate their ability for radionuclide absorption according to transfer factors (from soil and wood), to predict potential bioindicator species as well as species with potential risk for human use. Samples were taken during years 2011 and 2012, at two sites in forest ecosystem of Tara Mountain (Serbia). Observed concentration ranges per dry weight were as follows: 29-3,020 Bq/kg ((40)K), 21.9-735 Bq/kg ((137)Cs), 3-39 Bq/kg ((226)Ra), and 2.0-18 Bq/kg ((228)Ra). Obtained results indicate that the type of basidiome (fleshy/tough), most likely due to a different metabolic rate, has a very important role in radionuclide accumulation. The highest activity concentrations of all analyzed radionuclides were found in species with fleshy basidiomata--P. cervinus, H. clathroides, M. platyphylla, and Boletus species. A species-specific influence on radionuclide uptake was more prominent comparing to habitat differences and the role of fungal trophic mode. No significant variations were observed regarding radionuclide activity among the same fungal species from different sampling sites.
Abstract:The analyses of radioactive isotopes 14 C, 137 Cs and 210 Pb, and stable isotope 13 C were performed in the sediment cores, top 40 cm, taken in 2011 from karst lakes Prošće and Kozjak in the Plitvice Lakes National Park, central Croatia. Frozen sediment cores were cut into 1 cm thick layers and dried. 14 C activity in both carbonate and organic fractions was measured using accelerator mass spectrometry technique with graphite synthesis. 137 Cs, 210 Pb, 214 Pb and 214 Bi were measured by low level gamma spectrometry method on ORTECHPGe detector with the efficiency of 32%. Distribution of 14 C activity from both lakes showed increase of the 14 C activity in the top 10 − 12 cm in both carbonate and organic fractions as a response to thermonuclear bomb-produced 14 C in the atmosphere in the sixties of the 20th century. Anthropogenically produced 137 Cs was also observed in sediment profiles. Sedimentation rates for both lake sediments were estimated based on the unsupported 210 Pb activity. Different 14 C activity of the carbonate fraction (63−80 pMC, percent of modern carbon) and organic fraction (82 − 93 pMC) is the result of geochemical and biological processes of the sediment precipitation in the lake waters. This is also confirmed by the δ 13 C values of both fractions. Carbon isotope composition, 14 C and δ 13 C , was compared with the lake sediments from the same lakes collected in 1989 and 2003. 29.30 Kv, 91.65.Dt, 91.67.Qr, 91.67.Rx, 92.20.Td, 92.20.Xy PACS (2008):
More than 120 years after Roentgen's first X-ray image, the first cosmic-ray muon images of bone and soft tissue are created. The pictures, shown in the present paper, represent the first radiographies of structures of organic origin ever recorded by cosmic rays. This result is achieved by a uniquely designed, simple and versatile cosmic-ray muon-imaging system, which consists of four plastic scintillation detectors and a muon tracker. This system does not use scattering or absorption of muons in order to deduct image information, but takes advantage of the production rate of secondaries in the target materials, detected in coincidence with muons. The 2D image slices of cow femur bone are obtained at several depths along the bone axis, together with the corresponding 3D image. Real organic soft tissue, polymethyl methacrylate and water, never seen before by any other muon imaging techniques, are also registered in the images. Thus, similar imaging systems, placed around structures of organic or inorganic origin, can be used for tomographic imaging using only the omnipresent cosmic radiation.
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