Characteristics on Natural Radioactivity of Loess and Eolian Dust Origin Soils in East Asia

In order to investigate the characteristics on natural radioactivity of loess, desert sand and eolian dust origin soil distributed in East Asia, analyses for ^U, ^Th and ^K concentrations by ICP-MS and ICP-AES, and for major chemical composition, SiO_2, Al_2O_3, K_2O, etc., by XRF have been performed on 48 samples collected from the wide area of China and three prefectures of Japan. The results for loess samples indicated that the concentrations of natural radioactive elements and major chemical composition are almost homogeneous over Chinese Loess Plateau. Also the results suggested that the basic material of the red soils developed on Quaternary limestone in Okinawa prefecture, southwestern part of Japan, is not weathering residual from the base rock, but the eolian dust from the high background radiation area in the southeastern part of China. These observations could give important keys to understand the origin place of the eolian dust in East Asia during the Quaternary.
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