Vivianite and siderite in lateritic iron crust: an example of bioreduction

Química Nova

Vanda Porpino Lemos²  Marcondes Lima Da Costa²  Ronaldo Lima Lemos²  Mario Sergio Gomes De Faria¹ 

[1] ,Universidade Federal do Pará Centro de Geociências Belém PA ,Brasil

关键词: bioreduction;    siderite;    vivianite;   

DOI  :  10.1590/S0100-40422007000100008

来源: SciELO

【 摘 要 】

Lateritic iron crust (LIC) samples from Padauari (AM) were analysed by XRD, optical microscopy and SEM-EDS. The equilibrium of iron minerals (IM) was studied using Eh-pH diagram. It was shown that the minerals of the LIC are goethite (alpha-FeOOH), vivianite [Fe3(PO4)2.8H2O] and siderite (FeCO3). Carbonate grains are a solid solution of FeCO3-MnCO3. The LIC presents textures and structures of dissolution of IM. The siderite and vivianite are stable from Eh =-0.3 to 0.0 V and pH=5.0-7.5. These results indicate that vivianite and siderite are products of bioreduction through biogenic dissolution of IM, the new conditions of ecosystems of the Amazon region.

【 授权许可】

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