2 0 0 0 EXAFSを用いた土壌中における6価クロムの還元反応機構解明
土壌中の有機物や2価鉄などによって、有害な6価クロムが無害な3価クロムへ還元される反応は、環境化学的に重要である。演者らは、人工汚染土壌標準試料であるJSO-2(現在配布停止)中の6価クロムが、作成後5年以内に全て3価に還元されたことに着目し(Tsuno et al., 2006)、土壌中での有害元素の反応機構の解明に取り組んでいる。平成18年度の地球化学会年会(太田・津野・鍵・福良・野村・今井)では、状態分析法を用いて汚染土壌中のクロムの化学形態特定を行い、6価クロムが還元され3価の水酸化クロムとして存在していることを報告した。今回は、X線吸収端微細構造(EXAFS)解析を用いて詳細な構造解析を行うことで、その反応過程について新たに知見を得たので報告する。
- 著者
- 太田 充恒 南 雅代
- 出版者
- 一般社団法人日本地球化学会
- 雑誌
- 地球化学 (ISSN:03864073)
- 巻号頁・発行日
- vol.53, no.2, pp.59-70, 2019-06-25 (Released:2019-06-25)
- 参考文献数
- 31
We have elucidated retention of primary Sr isotopic ratios in source rocks to sediments and sedimentary rocks during repeated sedimentation recycling. Twenty-three fine stream sediments (<180 μm) in Awajishima Island were used for the study. The 87Rb/86Sr and 87Sr/86Sr of stream sediments originated from Cretaceous Ryoke granitic rocks and Cretaceous sedimentary rocks (Izumi Group) were similar to those of the respective source rocks. Incidentally, the 87Rb/86Sr-87Sr/86Sr of stream sediments in Awajishima Island suggests that Cretaceous felsic igneous rocks are the dominant source of clastics in Izumi Group. Stream sediments derived from Neogene and Quaternary sediments, which are originated from granitic rocks and Izumi Group, had comparable isotopic ratios to those of the respective primitive source rocks. Accordingly, 87Rb/86Sr and 87Sr/86Sr can be retained during the repeated recycling process of sediments and sedimentary rocks. Stream sediment is presumed to consist of clastics supplied from respective lithologies according to their exposed areas. However, 87Sr/86Sr of stream sediment is not comparable to the values calculated from exposed areas of lithologies and isotopic data of parent rocks. The result suggests that amount of sedimentation denudation and production differs among different lithologies and is not simply proportional to their exposed areas.