J. Phys. IV France
Volume 107, May 2003
Page(s) 505 - 508

J. Phys. IV France
107 (2003) 505
DOI: 10.1051/jp4:20030351

Stable Pb isotopes and PAHs as indicators of lead contamination sources in a lake of the Rouyn-Noranda area

C. Gallon1, C. Gobeil1, A. Tessier1 and R. Carignan2

1  INRS-ETE, Université du Québec, 2700 rue Einstein, CP. 7500, Sainte-Foy, Québec G1V 4C7, Canada
2  Département de Sciences Biologiques, Université de Montréal, Montréal, Québec H3C 3J7, Canada

We determined the depth distribution of total Pb and its stable isotope composition ( 206Pb/ 207Pb 206Pb/ 208Pb, 206Pb/ 204Pb) in a dated sediment core collected at the deepest site, in the hypolimnion of a headwater Canadian Shield lake, located 25 km downstream from a metal smelter in operation since 1927. The isotopic ratios reveal the occurrence of one natural and two anthropogenic types of Pb over the last century. One of the anthropogenic Pb, prédominant in the sediments accumulated in the early 20 $^{\rm th}$ century, likely derives from coal combustion ( $^{206}{\rm Pb}/^{207}{\rm Pb}\approx 1.185$). The second anthropogenic Pb has a signature similar to that of the ore processed during several decades at the smelter ( $^{206}{\rm Pb}/^{207}{\rm Pb} \approx 1.000$); its contribution to the total Pb concentration sharply increased from 1927 to 1975 and then decreased steadily to the sediment surface.

© EDP Sciences 2003