Present Century Record of Organolead Pollution in High Altitude Alpine Snow

Organolead compounds are tracers of lead additives used as anti-knocking agents in leaded gasoline, and snow/ice cores are useful archives of environmental pollution. Determination of these species in those archives provides information on their influence on the Pb pollution by monitoring the changes of organolead concentrations during the years. Organolead compounds have been analyzed by gas chromatography coupled to microwave-induced plasma atomic emission spectrometry (GC−MIP-AES) in a series of snow pit and snow/ice core samples deposited in a high altitude site in the Mont Blanc area between 1956 and 1994. Measured concentrations ranged from 0.1 to 3 pg/g for dimethyllead, 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 organolead compounds were detected in ice deposited before 1962. Concentrations of total alkyllead increased from 1962 till the late 1980s but then declined significantly during the 1990s. Changes in consumption of these species in France were compared with the obtained data. A delay of several years was observed between the restricted consumption of these additives and the subsequent decrease in concentrations observed in the ice. Furthermore, the data were compared with two records for organolead pollution obtained for the Northern Hemisphere: one for Central Greenland snow and the other for vintages originating from the Rhône Valley in southeast France.