Radioecological observations on plants of the lower Buller Gorge region of New Zealand and their significance for biogeochemical prospecting.
In a radioecological study of several common species of the Buller Gorge uraniferous area (South Island), the trees Nothofagus fusca and Weinmannia racemosa, and shrubs Coprosma australis and Quintinia acutifolia, were found to have both an alpha activity and U content well correlated with those of the soil. Uneven accumulation of U and alpha activity by the vegetation examined, however, confirmed the findings of other workers that much of the alpha count of plants is not attributable to U but to such daughter products as Ra, Pb, Th and Po, which may be more readily assimilable than U by some plants; the presence of these nuclides was confirmed by gamma-spectrometry. Analysis of successive annual rings of a 90-year-old N. fusca showed a marked lack of consistency between alpha activity and U content of the wood at different ages. KEYWORDS: plant composition \ plant composition \ chemical composition \ inorganic \ plant composition \ plant composition \ chemical composition \ inorganic trace elements \ Nothofagus fusca \ Radioactive substances \ plants \ Radioactivity \ trees, natural \ Weinmannia racemosa