A method for comprehensive speciation analysis of organolead compounds in polar snow at levels down to femtograms per gram is developed. The analytes are preconcentrated (250:1) in a singlestep extraction, derivatized by propylation using a Grignard reagent, and analyzed by capillary gas chromatography with microwave-induced plasma atomic emission detection (GC-MIP AED) after further on-line preconcentration (50:1). Extraction and derivatization efficiencies of organolead species at subprogram per gram levels and sources of the blank are extensively discussed. A number of snow samples collected at different locations in Greenland are analyzed, providing the first data on organolead levels in polar snow. Triand diethyllead species are the only compounds found in the majority of the samples.

Ionic alkyllead species have been determined in precisely dated consecutive layers of a 25-m-deep snow core obtained by drilling at the Summit site, relying on ultraclean sampling, high-resolution separation of individual species, and ultrasensitive determination procedures. Ethylleads were the only species found in the concentration ratio varying from 5 to 400 fg/g. The concentrations found show an increasing trend since the early 1970s until the late 1980s that is slightly blurred by seasonal variations. The results are correlated with the data on the distribution of organolead species in gasoline, the consumption levels of leaded gasoline in Europe and the United States, and the concentrations and isotopic compositions of total lead in particular samples. Unambiguous evidence of the gasolinerelated sources of lead in aged Greenland snow and ice during the past 70 years are provided. In contrast to Pb-(II), no dramatic drop in the northern hemispheric pollution by organic lead in the 1970s is observed.

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