J. Phys. IV France
Volume 107, May 2003
Page(s) 657 - 660

J. Phys. IV France
107 (2003) 657
DOI: 10.1051/jp4:20030389

Zn speciation in a soil contaminated by the deposition of a dredged sediment by synchrotron X-ray techniques

M.-P. Isaure1, 2, 1, N. Laboudigue2, Tamura1 and M.A. Marcus1

1  Environmental Geochemistry Group, LGIT-Maison des Géosciences, Université J. Fourier, CNRS, 38041 Grenoble cedex 9, France
2  Centre National de Recherche sur les Sites et Sols Pollués, 930 boulevard Lahure, BP. 537, 59505 Douai cedex, France

The nature and proportion of Zn species present in an agricultural soil overlaid by a dredged contaminated sediment have been untangled by the novel combination of three non-invasive synchirotron-based x-ray techniques: x-ray microfluorescence ( $\mu$SXRF), microdiffraction ( $\mu$XRD), and absorption spectroscopy (EXAFS). One primary (franklinite) and two secondary (phyllomanganate and phyllosilicate) Zn-containing minerals were identified in the initial soil, and another primary (ZnS) and a new secondary (Fe- (oxyhydr)oxide) Zn species in the covered soil. The quantitative analysis of EXAFS spectra recorded on bulk samples indicated that ZnS and Zn-Fe (oxyhydr)oxides amounted to $71\pm 10$% and $27\pm 10$%, respectively, and the other Zn species to less than 10%. The two new Zn species found in the covered soil result from the gravitational migration of ZnS particles initially present in the sediment, and from their further oxidative dissolution and fixation of leached Zn on Fe (oxyhydr)oxides.

© EDP Sciences 2003