A 250-year high-resolution record of Pb flux and crustal enrichment in central Greenland

[1] Records of contaminant deposition from ice cores document the impact of changing emissions on remote regions. While variations in Greenland ice core Pb concentrations before and after 1970 have been attributed primarily to leaded gasoline emissions, discontinuous coarse sampling in these studies provided limited temporal resolution. Using a continuous, high-resolution record of Pb and other trace element concentrations from 1750 to 1998, we show that large, sustained increases in Pb deposition in Greenland occurred >50 years before the introduction of leaded gasoline and that non-gasoline lead contamination likely accounted for >50% of the cumulative increase in lead deposition and crustal enrichment since industrialization. After 1970, mandated emission reductions led to a >75% decline in annual lead flux, with most of the decline occurring from 1970 to 1985. Additional elemental and isotopic tracers will be needed to provide Pb provenance.