Chemical and structural control of the partitioning of Co, Ce, and Pb in marine ferromanganese oxides

Geochimica et Cosmochimica Acta 71 巻 4 号 984-1008 頁 2007-02-15 発行
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タイトル ( eng )
Chemical and structural control of the partitioning of Co, Ce, and Pb in marine ferromanganese oxides
作成者
Manceau Alain
Geoffroy Nicolas
Marcus Matthew A.
Usui Akira
収録物名
Geochimica et Cosmochimica Acta
71
4
開始ページ 984
終了ページ 1008
抄録
The oxidation state and mineral phase association of Co, Ce, and Pb in hydrogenetic, diagenetic, and hydrothermal marine ferromanganese oxides were characterized by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy and chemical extraction. Cobalt is trivalent and associated exclusively with the Mn oxide component (vernadite). Cerium is tetravalent in all genetic-type oxides (detection limit for Ce(III) ~ 5 at. %), including Fe-rich areas (ferrihydrite) of hydrogenetic oxides, and is associated primarily with vernadite. Thus, the extent of a Ce anomaly does not result from variations in redox conditions, but appears to be kinetically controlled, decreasing when the growth rate increases from hydrogenetic to diagenetic to hydrothermal oxides. Lead is divalent and associated with Mn and Fe oxides in variable proportions. According to EXAFS data, Pb is mostly sorbed on edge sites at chain terminations in Fe oxide and at layer edges in Mn oxide (ES complex), and also on interlayer vacancy sites in Mn oxide (TCS complex). Sequential leaching experiments, spectroscopic data, and electrochemical considerations suggest that the geochemical partitioning in favor of the Mn oxide component decreases from Co to Ce to Pb, and depends on their oxidative scavenging by Mn and Fe oxides.
NDC分類
化学 [ 430 ]
言語
英語
資源タイプ 学術雑誌論文
出版者
Pergamon-Elsevier Science Ltd.
発行日 2007-02-15
権利情報
Copyright (c) 2006 Elsevier Inc.
出版タイプ Author’s Original(十分な品質であるとして、著者から正式な査読に提出される版)
アクセス権 オープンアクセス
収録物識別子
[ISSN] 0016-7037
[DOI] 10.1016/j.gca.2006.11.016
[NCID] AA00655038
[DOI] http://dx.doi.org/10.1016/j.gca.2006.11.016