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Kawamoto, Keisuke*; Ochiai, Asumi*; Takeda, Ayaka*; Nakano, Yuriko*; Yokoo, Hiroki*; Oki, Takumi*; Onuki, Toshihiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Utsunomiya, Satoshi*
no journal, ,
In the Ningyo-toge uranium mine, Okayama, Japan, various toxic elements such as U, As, and Ra are present in the mine wastewaters, of which the concentration except for Ra in the wastewater decrease below the regulatory limit by transport to the slag dumping pond. The mechanisms of decreasing their concentrations in the wastewaters are not fully understood. In order to understand the fundamental processes of natural attenuation at this site, we have investigated the wastewaters and solids from upstream to the pond at the downstream. Wastewater was contacted with oxygenated water and the amount of dissolved oxygen increased. Simultaneously dissolved ferrous iron was oxidized to form ferrihydrite nanoparticles, which are associated with silica colloids, As and U. The ferrihydrite nanoparticles as suspended colloids were transported to the pond in downstream, where the waste stream is completely oxidized. In the slag dumping pond, Mn dioxide, birnessite, dominantly occurs forming a mixture with ferrihydrite + silica colloid, which has a potential to adsorb Ra
. Consequently, Fe hydroxides nanoparticles and Mn dioxides in Ningyo-toge play a key role on removing U, As and Ra from the wastewater.
Kitagaki, Toru
no journal, ,
Zircon dissolution rates under flowing aqueous solutions of pH 0 (HCl), 7 (H
O), 14 (NaOH aq) were in-situ measured from the zircon surface change by Phase-shift interferometric microscope.
Ogita, Yasuhiro; Yuguchi, Takashi*; Kato, Takenori*; Yokota, Rintaro*; Sasao, Eiji; Nishiyama, Tadao*
no journal, ,
no abstracts in English