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Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentiere, France)

Guillaume Morin, Farid Juillot, Philippe Ildefonse, Georges Calas, Jean-Claude Samama, Pierre Chevallier and Gordon E. Brown
Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentiere, France)
American Mineralogist (February 2001) 86 (1-2): 92-104

Abstract

Lead speciation was determined in a soil developed on a geochemical anomaly arising from a Pb-Zn stratabound deposit in Largentiere (Ardeche, France). This geological setting offers the opportunity to determine the preferred form(s) of Pb following soil formation on this unique anomaly. In the soil profile studied, Pb concentrates in the B-horizon (2055 mg/kg Pb) relative to both the A- (1330 mg/kg Pb) and C- (1874 mg/kg Pb) horizons. Plumbogummite (PbAl (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 5) . H (sub 2) O) is the main host of Pb in the soil profile. Pb also appears to be associated with Mn-(hydr)oxides, as shown by micro-analyses (EMPA, SEM-EDS, and mu -SXRF), in the form of inner-sphere Pb (super 2+) complexes, as suggested by Pb L (sub m) -edge EXAFS spectroscopy. Linear least-squares fitting of background-subtracted, k (super 3) -weighted Pb L (sub m) -edge EXAFS functions derived from bulk soil samples was carried out using Pb L (sub m) -EXAFS spectra of 22 Pb-containing model compounds. Quantitative assessment of Pb speciation revealed that, whereas plumbogummite is the most abundant Pb phase in the soil profile, Pb (super 2+) -Mn-(hydr)oxide surface complexes are gradually replaced by Pb (super 2+) -surface complexes with other phases, possibly Pb (super 2+) -organic complexes, upward in the soil profile. The presence of large amounts of Pb-phosphate in the Largentiere soil suggests that low solubility phosphates may be important long-term hosts of Pb in Pb-contaminated soils that have sufficiently high phosphorous activities to cause formation of these phases.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 86
Serial Issue: 1-2
Title: Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentiere, France)
Affiliation: Universites de Paris VI et VII, Laboratoire de Mineralogie-Cristallographie, Paris, France
Pages: 92-104
Published: 200102
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 71
Accession Number: 2001-073735
Categories: Mineralogy of non-silicatesGeochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N44°32'60" - N44°32'60", E04°17'60" - E04°17'60"
Secondary Affiliation: Ecole Nationale Superieure de Geologie, FRA, FranceUniversite de Paris XI, FRA, FranceStanford University, USA, United StatesStanford Synchrotron Radiation Laboratory, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200123
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