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Solid‐Phase Iron Characterization During Common Selective Sequential Extractions
Author(s) -
La Force Matthew J.,
Fendorf Scott
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.6451608x
Subject(s) - chemistry , nitric acid , hydrochloric acid , nuclear chemistry , inorganic chemistry , solid phase extraction , extraction (chemistry) , chromatography
Selective chemical extractions provide semiquantitative information on elemental partitioning within operationally defined soil fractions. In this study, the efficiency of common extraction steps was determined for a mining‐impacted soil by analyzing Fe transformations in the solid phase using x‐ray diffraction, scanning electron microscopy, and x‐ray absorption near edge structure (XANES) spectroscopy. Extractions involve the isolation of operationally defined double‐deionized water (soluble), magnesium chloride (exchangeable), sodium hypochlorite (organic matter), sodium acetate–acetic acid (carbonate), hydroxylamine‐hydrochloride–nitric acid (Mn‐oxides), ammonium oxalate in the dark (AOD) (noncrystalline material), hydroxylamine‐hydrochloride–acetic acid (Fe oxides), potassium perchlorate–hydrochloric–nitric acid (sulfidic), and hydrochloric–nitric–hydrofluoric acid (residual) fractions of the solid phase. Ferric Fe remained in the solid phase throughout the extraction sequence until its removal by hydrochloric–nitric–hydrofluoric acid (residual fraction). The hydroxylamine‐hydrochloride (1.0 M in 25% [v/v] HOAc) extraction may underestimate Fe associated with crystalline materials. Thus, selective sequential extractions need to be optimized for a given soil prior to implementation and should be used in conjunction with spectroscopic techniques, when possible, to fully ascertain elemental partitioning within the solid phase.