The Medieval metal industry was the cradle of modern large scale atmospheric lead pollution in northern Europe

There is great concern for contamination of sensitive ecosystems in high latitudes by long-range transport of heavy metals and other pollutants derived from industrial areas in lower latitudes. Atmospheric pollution of heavy metals has a very long history, and since metals accumulate in the environment, understanding of present-day pollution conditions requires knowledge of past atmospheric deposition. We use analyses of lead concentrations and stable lead isotopes ((206)pb/(207)pb ratios) Of annually laminated sediments from four lakes in northern Sweden (similar to 65 degrees N) to provide a decadal record of atmospheric lead pollution far the last 3000 years. There is a clear signal in the sediments of airborne pollution from Greek and Roman cultures 2000 yea rs ago, followed by a period of "clean" conditions 400-900 A.D. From 900 A.D. there was a conspicuous, permanent increase in atmospheric lead pollution fallout. The sediments reveal peaks in atmospheric lead pollution at 1200 and 1530 A.D. comparable to present-day levels. These peaks match the history of metal production in Europe. This study indicates that the contemporary atmospheric pollution climate in northern Europe was established in Medieval time, rather than in the industrial period. Atmospheric lead pollution deposition did not, when seen in a historical perspective, increase as much as usually assumed with the Industrial Revolution (1800 A.D.).