Present century record of organolead pollution in high altitude alpine snow

Organolead compounds are tracers of lead additives used as anti-knocking ag ents in leaded gasoline, and snow/ ice cores are useful archives of environ mental pollution. Determination of these species in those archives provides information on their influence on the Pb pollution by monitoring the chang es of organolead concentrations during the years. Organolead compounds have been analyzed by gas chromatography coupled to microwave-induced plasma at omic emission spectrometry (GC-MIP-AES) in a series of snow pit and snow/ic e core samples deposited in a high altitude site in the Mont Blanc area bet ween 1956 and 1994. Measured concentrations ranged from 0.1 to 3 pg/g for d imethyllead, from 0.08 to 3.4 pg/g for trimethyllead, from 0.01 to 0.57 pg/ g for diethyllead, and from 0.01 to 0.13 pg/g for triethyllead. No organole ad compounds were detected in ice deposited before 1962. Concentrations of total alkyllead in cre a sed from 1962 till the late 1980s but then decline d significantly during the 1990s. Changes in consumption of these species i n France were compared with the obtained data. A delay of several years was observed between the restricted consumption of these additives and the sub sequent decrease in concentrations observed in the ice. Furthermore, the da ta were compared with two records for organolead pollution obtained for the Northern Hemisphere: one for Central Greenland snow and the other for vint ages originating from the Rhone Valley in southeast France.