TY - JOUR
T1 - Improved methods for selective dissolution of Mn oxides
T2 - Applications for studying trace element associations
AU - Neaman, Alexander
AU - Mouélé, Flore
AU - Trolard, Fabienne
AU - Bourrié, Guilhem
N1 - Funding Information:
We thank Dr. Jean-Claude Germanique (CEREGE) and the staff of SARM-CRPG (Nancy) for chemical analyses, and Dr. Daniel Borschneck (CEREGE) for kind consideration and much helpful advice with X-ray diffraction analyses. We also thank the European Commission (EU Structural Funds, Objective 2) for equipping the INRA laboratory, and INRA for the scholarship awarded to A. Neaman.
PY - 2004/6
Y1 - 2004/6
N2 - The association of rare earth and other trace elements with Fe and Mn oxides was studied in Fe-Mn-nodules from a lateritic soil from Serra do Navio (Northern Brazil). Two improved methods of selective dissolution by hydroxylamine hydrochloride and acidified hydrogen peroxide along with a classical Na-citrate-bicarbonate-dithionite method were used. The two former reagents were used to dissolve Mn oxides without significant dissolution of Fe oxides, and the latter reagent was used to dissolve both Mn and Fe oxides. Soil nodules and matrix were separated by hand. Inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry after fusion with lithium metaborate, and X-ray diffraction were used to determine the elemental and mineralogical composition of the nodules and soil matrix. The latter was composed of kaolinite, gibbsite, goethite, hematite, and quartz. In the nodules, lithiophorite LiAl2(MnIV2Mn III)O6(OH)6 was detected in addition to the above-mentioned minerals. The presence of hollandite (BaMn8O 16) and/or coronadite (PbMn8O16) in the nodules is also possible. In comparison to the matrix, the nodules were enriched in Mn, Fe, K, and P, and relatively poor in Si, Al, and Ti. The nodules were also enriched in all trace elements determined. Phosphorus, As and Cr were associated mainly with Fe oxides; Cu, Ni, and V were associated with both Fe and Mn oxides; and Ba, Co, and Pb were associated mainly with Mn oxides. Distribution of rare earth elements indicated a strong positive Ce-anomaly in the nodules, compared to the absence of any anomaly in the matrix. Some of Ce was associated with Mn oxides. The improved methods achieved almost complete release of Mn from the sample without decreasing the selectivity of dissolution, i.e., without dissolving significant amounts of Fe oxides and other minerals, and provided reliable information on associations of trace elements with Mn oxides. These methods are thus proposed to be included in sequential extraction schemes for fractionation of trace elements in soils and sediments.
AB - The association of rare earth and other trace elements with Fe and Mn oxides was studied in Fe-Mn-nodules from a lateritic soil from Serra do Navio (Northern Brazil). Two improved methods of selective dissolution by hydroxylamine hydrochloride and acidified hydrogen peroxide along with a classical Na-citrate-bicarbonate-dithionite method were used. The two former reagents were used to dissolve Mn oxides without significant dissolution of Fe oxides, and the latter reagent was used to dissolve both Mn and Fe oxides. Soil nodules and matrix were separated by hand. Inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry after fusion with lithium metaborate, and X-ray diffraction were used to determine the elemental and mineralogical composition of the nodules and soil matrix. The latter was composed of kaolinite, gibbsite, goethite, hematite, and quartz. In the nodules, lithiophorite LiAl2(MnIV2Mn III)O6(OH)6 was detected in addition to the above-mentioned minerals. The presence of hollandite (BaMn8O 16) and/or coronadite (PbMn8O16) in the nodules is also possible. In comparison to the matrix, the nodules were enriched in Mn, Fe, K, and P, and relatively poor in Si, Al, and Ti. The nodules were also enriched in all trace elements determined. Phosphorus, As and Cr were associated mainly with Fe oxides; Cu, Ni, and V were associated with both Fe and Mn oxides; and Ba, Co, and Pb were associated mainly with Mn oxides. Distribution of rare earth elements indicated a strong positive Ce-anomaly in the nodules, compared to the absence of any anomaly in the matrix. Some of Ce was associated with Mn oxides. The improved methods achieved almost complete release of Mn from the sample without decreasing the selectivity of dissolution, i.e., without dissolving significant amounts of Fe oxides and other minerals, and provided reliable information on associations of trace elements with Mn oxides. These methods are thus proposed to be included in sequential extraction schemes for fractionation of trace elements in soils and sediments.
UR - http://www.scopus.com/inward/record.url?scp=1942456815&partnerID=8YFLogxK
U2 - 10.1016/j.apgeochem.2003.12.002
DO - 10.1016/j.apgeochem.2003.12.002
M3 - Article
AN - SCOPUS:1942456815
SN - 0883-2927
VL - 19
SP - 973
EP - 979
JO - Applied Geochemistry
JF - Applied Geochemistry
IS - 6
ER -