J. Phys. IV France
Speciation and mobility of Zn, Cu and Pb in a truck farming soil
contaminated by sewage irrigation
T. Kirpichtchikova1, 2, A. Manceau1, B. Lanson1, M.A. Marcus3 and T. Jacquet2
Environmental Geochemistry Group, LGIT, Université J. Fourier, CNRS, BP. 53,
38041 Grenoble cedex 9, France2
Site et Concept, 16 rue Jules Vallées, 75011 Paris, France3
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.
The forrns and mobility of Cu (290 mg/kg), Zn (1103 mg/kg), and Pb (535 mg/kg) in a soil used for
intensive truck farining from the Region Ile-de-France, and which has been irrigated for more than a century with
sewage water ftom the city of Paris, have been studied by chemical treatments and advanced x-ray techniques.
Elemental associations and forms of metals were determined qualitatively and quantitatively by a combination of
physical techniques, including
PIXE (Cu, Zn, Pb),
SXRF (Cu, Zn),
EXAFS (Zn) and powder EXAFS (Zn). The
nature, number, and relative proportion of Zn species were obtained by principal component analysis and
decomposition of Zn K-edge EXAFS spectra. These data collectively indicate that Cu is associated mainly with
organic matter, and that Zn and Pb are bound essentially to mineral constituents. Four Zn-containing species were
positively identified: Zn-phosphate and phyllosilicate as dominant species, and Zn-Fe oxyhydroxide and willemite
) as minor species. Studies are underway to determine the structural forms of Cu and Pb. Depending on the
chemical treatment, up to 70% Cu, ~50% Zn, and ~85% Pb can be removed in a few days with citrate and EDTA.
Citrate is generally at least as efficient as EDTA, and it has the advantage ofbeing easily biodegradable and, hence,
less harmful to ecosystems.
© EDP Sciences 2003