J. Phys. IV France
Volume 107, May 2003
Page(s) 483 - 486

J. Phys. IV France
107 (2003) 483
DOI: 10.1051/jp4:20030346

Isotopic evidence of spatial magnitude of the Pb deposition near a lead smelter

P. Flament1, M. Franssens2, K. Debout1 and D. Weis2

1  Université du Littoral - Côte d'Opale, LABEL, UMR 8013 du CNRS, ELICO, 32 avenue Foch, 62930 Wimereux, France
2  Université Libre de Bruxelles, Département Sciences de la Terre et de l'Environnement, CP 160/02, 1050 Brussels, Belgium

In order to détermine the dry deposition of lead around a Pb-Zn refinery, two cross-sectional sampling experiments, using deposition plates, have been performed on a daiiy basis, ucder representative meteorological situations (north-easterly and south-westerly winds). The amount of lead deposited as well as its isotopic composition (expressed by the 206Pb/ 207Pb ratio) are systematically measured. For a daily production of approximately 670 metric tons of (Pb+Zn) the dry fallout, greater than 1000  $\mu$g Pb.h -1.m -2 on the edge of the plant, falls to about 100  $\mu$g Pb.h -1.m -2, four kilometres away from the refinery. This value is still ten times higher than th urban background ( <10  $\mu$g Pb.h -1.m -2). The spatial extension of the dry deposition plume is evidenced by the evolution of the isotopic signature of the refinery (1.10 < 206Pb/ 207), clearly distinct from the urban backgrounde signature (1.15 < 206Pb/ 207Pb <1.16). As a first estimate, the extension of the deposition plume seems not to be linked to the wind speed. At the opposite, diffuse emissions from slag heaps are related to this parameter.

© EDP Sciences 2003