%0 Journal Article
%T Quantitative Estimation of Fougerite Green Rust in Soils and Sediments by Citrate¡ªBicarbonate Kinetic Extractions
%A Fabienne Trolard
%A Fr¨¦d¨¦ric Feder
%A Goestar Klingelh£¿fer
%A Guilhem Bourri¨¦
%J -
%D 2018
%R https://doi.org/10.3390/soilsystems2040054
%X Abstract Fougerite (IMA 203-057), from green rust (GR) group, is difficult to quantify due to its reactivity and its small concentration in soils and sediments. Chemical extractions with citrate-bicarbonate (CB) reagent, in kinetic mode, can be used for a pre-diagnosis. Performed by steps (0, 1, 6, 48, 168 and 504 h), the proposed protocol was applied on samples from Gleysol of Foug¨¨re¡¯s forest with mineralogical controls by M£¿ssbauer and XRD (X-ray diffraction) after each step of extraction. In less than 6 h, the first fraction extracted is composed of 70% Si, 80% Al, 23% Fe and 80% Mg of total element extractable by CB and is ascribed to the ¡°indefinable mineral mixture Si-Al-Fe¡± named by Tamm. Between 6 and 168 h, the second fraction extracted is composed of Fe and Mg with a constant mole ratio Fe/Mg equal to 10 and is ascribed to the fougerite-GR phase. Analysis of XRD pattern and of M£¿ssbauer spectra confirms: (i) all the other mineral phases containing Al, Mg, Si were not dissolved by CB after 6 h; (ii) the CB treatment extracts fougerite-GR completely. The residual fraction is composed of components not dissolved by CB extraction. Thus, the selectivity of CB can be used to quantitatively estimate the presence of fougerite-GRs in soils and sediments. View Full-Tex
%K green rust
%K fougerite
%K citrate-bicarbonate extraction
%K M£¿ssbauer
%K iron
%K Fe
%K gley
%K hydromorphy
%U https://www.mdpi.com/2571-8789/2/4/54