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- Author or Editor: H. Kofuji x
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Abstract
In the usual measurements of radionuclides in the environmental samples by g-ray spectrometry, Compton scattering of 1461 keV g-rays from 40K severely interferes with the detection of artificial radionuclides in marine and agricultural products. In order to eliminate the interference of 40K, we have developed a simple and convenient 
water leaching treatment
method applicable to seaweed (sargasso) samples. By this treatment, over 98% of the potassium in seaweed samples is removed without notable losses of artificial and/or natural radionuclides. In combination with the low-level g-ray counting in the Ogoya underground laboratory, the detection limit could be improved by ~1 order of magnitude.
Summary
In connection with the investigation of acid depositions, a reliable method for the determination of the cosmogenic radionuclide 35S in precipitation was developed, and atmospheric depositions of 35S and SO4 2- have been measured every ten days at Tatsunokuchi,in a heavy-snowfall area facing to the Sea of Japan for two years during 1998-1999. Consistent seasonal cycles were found for the atmospheric depositions of 35S and non-sea salt sulfate (nss-SO4 2-), in which both depositions were high in winter and low in other seasons. A similar wet scavenging mechanism was suggested to be involved in the association of 35S and SO4 2-.
Abstract
The concentration of pore water uranium in six sediments from oligotrophic, mesotrophic, acidotrophic and dystrophic lakes was measured by inductively coupled plasma-mass spectrometry. Profiles of pore water U can be divided into two groups such as low (17±7 ng/l) and high concentration (69±30 ng/l). These values were 1–2 orders of magnitude higher than that of lake waters (6±4 ng/l) due to the release of U from the sediments by decomposition of organic materials. Variations in pore water U concentrations seem to relate to the differences in pore water pH, the association forms, and their contents of U in the lake sediments.
