| Research Abstract |
1. Diagenetic behavior of sulfur and selenium in semimentary organic materials
River waters and river sediments in the dry provinces (Heshi Corridor, Heihe River, ShiyanHe River), lake waters and sediments in a salt lake (Qinhai Province, Qinhai Lake), and a freshwater lake in the temperate zones (Yunnan Province, Erhai Lake) have been sampled. Sulfur and selenium in the various organic fractions of these samples were determined. Also water and sediment samples were collected from urban rivers (Tamagawa R.and its estuary) and water channels (Tatekawa, Kitajyukkenngawa) and analyzed in the same way. These results strongly indicates that selenium in the regions of less human impact tends to be mainly transported with organic materials in the waters and sediments while sulfur has more multiple channels of its transportation. The distribution of sulfur and selenium in the organic sediments occupies their own concentration ranges. Based on this facts, we can estimate ancient sedimentary envi
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ronments by analyzing S and Se in the sediments.
2. Geochemical behavior of sulfur species in hydrothermal environments
Polythionates in active crater lakes in Indonesia (Kawah Ijen, Kawah Putih, Teraga Bodas) have been determined and the present volcanic activity of these volcanoes and the mechanism of hydrothermal reactions proceeding in these lakes were estimated on these data. Furthermore, sulfur isotopic consideration on the disproportionation of sulfur dioxide proceeding under the craterlake has been given to the most active crater lake, Crater Lake at Ruapehu Volcano in New Zealand. We also conducted the international analitical contest for the active crater lake water, pointed out the problems in analysis, and proposed some guidlines for better chemical analysis of this kind of natural waters.The planned characterization of sulfur species in hydrothermal fluids for forming Lapis Lazuri was unsuccessful during the term of this project, because of unexpected low sensitivity of our Raman spectrometer for detection of aimed sulfur species. The monitoring of polonium in molten sulfur in active crater lakes was also under way to the monitoring of polonium by ICP-MS. Less
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