Staff

Numa Pfenninger

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Numa Pfenninger

Technician

Department Water Resources & Drinking Water

About Me

I am a technician, working for two different research groups. I am interested in the interaction between solids (e.g., soils, filter materials) and water, involved in different research projects. An important part of my job is to support students and postdocs as well as the training of apprentices (lab technicians).

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Publications

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Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock

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.
Voegelin, A.; Pfenninger, N.; Petrikis, J.; Majzlan, J.; Plötze, M.; Senn, A.-C.; Mangold, S.; Steininger, R.; Göttlicher, J. (2015) Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock, Environmental Science and Technology, 49(3), 5390-5398, doi:10.1021/acs.est.5b00629, Institutional Repository

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Address

E-Mail: numa.pfenninger@eawag.ch
Phone: +41 58 765 6849
Fax: +41 58 765 5802
Address: Eawag
Überlandstrasse 133
8600 Dübendorf
Office: LA C67
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Research Group

Molecular Environmental Geochemistry

Environmental Inorganic Geochemistry

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