NORTHERN HEMISPHERIC ORGANIC LEAD EMISSIONS IN FRESH GREENLAND SNOW

Ionic alkyllead species have been determined in fresh or slightly aged surface snow from Greenland relying on ultraclean sampling, high-resolution separation of individual species, and ultrasensitive determination procedures. The samples were collected from January to August 1989 on a precipitation event basis at Dye 3 (south Greenland) and in late spring and summer 1987 and 1989 at or near the Summit site (central Greenland). Evidence for long-range transport of organolead compounds into the very remote environment is given, and the nature and extent of the global pollution by organolead compounds are evaluated. Triethyl- and diethyllead species were found in all the samples, whereas methyllead species were absent in the late spring and summer samples. Monoalkyllead, mixed ionic organolead, and tetraalkyllead species were always found to be below 10-20 fg/g. The average total organolead concentrations form January to April was very high (476 fg/g, values between 100 and 800 fg/g, 0.3-2% of the total Pb), whereas the average summer concentration (May-August) was a factor of 5 lower (82.6 fg/g, values between 15 and 220 fg/g, less than 0.4% of the total lead). The variations in the concentrations measured are interpreted in terms of backwards air mass trajectories. Source regions influencing Dye 3 at different times are indicated. Organolead compounds in Greenland are established to be valuable indicators of the global character of the lead pollution originated specifically in the use of leaded gasoline.