title: Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock.
abstract: We investigated the speciation and extractability of Tl in soil developed from mineralized carbonate rock. Total Tl concentrations in topsoil (0-20 cm) of 100-1000 mg/kg are observed in the most affected area, subsoil concentrations of up to 6000 mg/kg Tl in soil horizons containing weathered ore fragments. Using synchrotron-based microfocused X-ray fluorescence spectrometry (μ-XRF) and X-ray absorption spectroscopy (μ-XAS) at the Tl L3-edge, partly Tl(I)-substituted jarosite and avicennite (Tl2O3) were identified as Tl-bearing secondary minerals formed by the weathering of a Tl-As-Fe-sulfide mineralization hosted in the carbonate rock from which the soil developed. Further evidence was found for the sequestration of Tl(III) into Mn-oxides and the uptake of Tl(I) by illite. Quantification of the fractions of Tl(III), Tl(I)-jarosite and Tl(I)-illite in bulk samples based on XAS indicated that Tl(I) uptake by illite was the dominant retention mechanism in topsoil materials. Oxidative Tl(III)uptake into Mn-oxides was less relevant, probably because the Tl loadings of the soil exceeded the capacity of this uptake mechanism. The concentrations of Tl in 10 mM CaCl2-extracts increased with increasing soil Tl contents and decreasing soil pH, but did not exhibit drastic variations as a function of Tl speciation. With respect to Tl in contaminated soils, this study provides first direct spectroscopic evidence for Tl(I) uptake by illite and indicates the need for further studies on the sorption of Tl to clay minerals and Mn-oxides and its impact on Tl solubility in soils.
authors.affiliation: †Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Voegelin
authors.affiliation: †Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland.
authors.forename: Numa
authors.initials: N
authors.lastname: Pfenninger
authors.affiliation: ‡Friedrich-Schiller-University Jena, Institute of Geosciences, Mineralogy, Burgweg 11, D-07749 Jena, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Petrikis
authors.affiliation: ‡Friedrich-Schiller-University Jena, Institute of Geosciences, Mineralogy, Burgweg 11, D-07749 Jena, Germany.
authors.forename: Juraj
authors.initials: J
authors.lastname: Majzlan
authors.affiliation: §ETH Zurich, Institute for Geotechnical Engineering, CH-8093 Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Plötze
authors.affiliation: †Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland.
authors.forename: Anna-Caterina
authors.initials: AC
authors.lastname: Senn
authors.affiliation: ∥Karlsruhe Institute of Technology, ANKA Synchrotron Radiation Facility, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mangold
authors.affiliation: ∥Karlsruhe Institute of Technology, ANKA Synchrotron Radiation Facility, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Steininger
authors.affiliation: ∥Karlsruhe Institute of Technology, ANKA Synchrotron Radiation Facility, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Göttlicher
mesh_terms: D000143:Acids / Q000737:chemistry; D001151:Arsenic / Q000032:analysis*; D002254:Carbonates / Q000032:analysis*; D004787:Environmental Pollution / Q000032:analysis; D005290:Ferric Compounds / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013052:Spectrometry, X-Ray Emission; D013431:Sulfates / Q000737:chemistry; D013557:Switzerland; D013793:Thallium / Q000032:analysis*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000143:Acids; D002254:Carbonates; D005290:Ferric Compounds; D008903:Minerals; D010070:Oxalates; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; C492331:jarosite; C099089:illite; D013793:Thallium; D001151:Arsenic