PREINDUSTRIAL ATMOSPHERIC LEAD CONTAMINATION DETECTED IN SWEDISH LAKE-SEDIMENTS

DESPITE evidence from Greenland ice cores for pre-industrial atmospheric trace-metal contamination(1,2) it is commonly assumed that air pollution in remote areas is a recent problem caused by industrial activities, fossil-fuel burning and emissions from motor vehicles. Here we report analyses of lake sediments from Sweden showing that atmospheric lead deposition increased above background levels more than 2,600 years ago. There was a small, but marked lead deposition peak about 2,000 years ago, and a more significant increase that began 1,000 years ago and accelerated during the nineteenth and particularly the twentieth centuries, with a deposition maximum at about AD 1970. Before the nineteenth century industrialization, lead concentrations in lake sediments from southern Sweden had already reached 10-30 times previous background levels as a result of atmospheric deposition. We suggest that this pre-industrial airborne pollution was derived from extensive production and use of lead in Europe, starting with the Greek and Roman cultures(3,4). The cumulative deposition from anthropogenic sources in pre-industrial times (similar to 600 BC to AD 1800) was at least as large as the cumulative deposition during the industrial period (AD 1800 to the present).