Development of negative Ce anomalies in biogenic Mn oxide; The Role of microorganism on REE mobility during the bio-oxidation of Mn

生物起源マンガン酸化物によるCe吸着の負の異常原因の解明

Yu, Q.; 大貫 敏彦; 田中 万也*  ; 香西 直文   ; 山崎 信哉; 坂本 文徳  ; 谷 幸則*

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Yamasaki, Shinya; Sakamoto, Fuminori; Tani, Yukinori*

Bio-oxidation of Mn is ubiquitously occurring in most aquatic and terrestrial environments, which strongly affected the migration of trace elements as well as radionuclides under environmental condition. In the present work, sorption of REEs during bio-oxidation and precipitation of Mn was investigated using Acremonium sp. strain KR21-2 under neutral pH conditions. The sorption ratio of REE decreased with increasing citrate concentration, but more negative Ce anomaly was observed for the sample without citrate, and in citrate concentration higher than 0.4 mM. In both cases, the oxidation of Mn was suppressed. The analysis of HPLC showed that additional organic molecules were released from hyphae when Mn bio-oxidation was suppressed. This observation suggests that, microbe activity strongly influences oxidation state as well as chemical speciation of Ce, which consequently affect the migration of Ce in waters system.