Lead isotopic fingerprinting of 250-years of industrial era pollution in Greenland ice

Emissions from mid-latitude industrial activities (e.g., mining, smelting, coal combustion) result in long-range atmospheric transport of lead (Pb) to the Arctic. While previous measurements of elemental concentrations and Pb isotopic ratios in ice and sediments have been used to suggest potential sources of toxic heavy metal pollution in these regions, high resolution Pb isotope records are largely unavailable due to the low Pb concentrations found in Arctic ice. Here we present and interpret a high-resolution, 1759-2008 record of Pb isotopes measured in a central Greenland ice core; the first high-resolution Pb isotope record for Greenland to include the First Industrial Revolution. Records of past industrial activities coupled with Pb isotopic signatures for regional ores and coals suggest Pb pollution prior to the mid-19th century was dominated by emissions from mining and combustion of coals in England, Scotland, and Wales. Rapid 1860s increases in Pb levels and decreases in Pb-206/Pb-207 ratios coincided with expansion of coal consumption in Europe and North America. Significant influence of 20th century smelting of Australian Broken Hill Pb ores in Europe resulted in a less radiogenic Pb isotope signature. The phase-out of leaded gasoline and other emissions reductions following passage of air quality legislation in the United States had a pronounced effect on Pb-206/Pb-207 ratios, with values falling from 1.187 in 1978 to 1.154 in 1983. Increasing Pb-208/Pb-207 ratios through the 1990s and 2000s indicate rising influence of long-range transport from Asia countering declines in European emissions. This 250-year high resolution Pb isotope reconstruction allows attribution of Pb sources to central Greenland with unprecedented detail.

Automated summary

This article presents a high-resolution, 1759-2008 record of lead isotopes measured in a central Greenland ice core. The study provides detailed tracing of lead pollution from mid-latitude industrial activities over a 250-year period. The results suggest that mining and coal combustion in England, Scotland, and Wales were the dominant sources of lead pollution prior to the mid-19th century. The expansion of coal consumption in Europe and North America led to rapid increases in lead levels and changes in lead isotope ratios. The smelting of Australian Broken Hill lead ores in Europe and long-range transport from Asia also influenced the lead isotope signatures.