岐阜県東濃ウラン鉱床地域における地下水・地表水中のウラン系列核種(^<238>U, ^<234>U, ^<226>Ra, ^<222>Rn)の挙動

概要

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Uranium series nuclides such as ^<238>U, ^<234>U, ^<226>Ra and ^<222>Rn, were measured in the groundwaters and surface waters around the Tono uranium mine and their geochemical behaviors and hydrogeochemical implications were investigated. ^<238>U contents in the groundwaters were low because the groundwater was reducing and its pH was high. ^<226>Ra contents were higher than the equilibrium amounts of ^<238>U, which suggests that radium is easy to move than uranium. ^<222>Rn was abundant in the groundwaters from several hundreds times to several ten thousands times than its precursor ^<226>Ra, which inferred that much amount of radon was supplied by the rocks and ore body through micro paths. ^<234>U /^<238>U activity ratios of some groundwaters were high (about 6). It may be because the water is reducing and uranium is leached from the clay minerals that adsorb uranium relatively weakly. The waters from the Sublevel gallery of the Tono mine were low in radon content and ^<222>Rn /^<226>Ra activity ratios, which suggests that the water originated not in the deep groundwater, but in the shallow groundwater.
日本地球化学会の論文
1991-03-20