Even the ancient Romans…
The question of the extent to which air pollution is caused by human activities or is also caused by natural occurrences is repeatedly discussed. When analyzing a Greenland ice sample, scientists from Australia and France found evidence that lead from mines was already heavily polluting the atmosphere in Roman times. Already 300 years before Christ there was a heavy pollution of the atmosphere with lead in the northern hemisphere. Chemical analysis of an approximately 275-meter-long piece of core from the Greenland ice has provided unmistakable evidence. dr Kevin J. Rosman of Curtin University of Technology in Perth, Australia, traces the source of this contamination to ancient Carthaginian and Roman mines in Spain. Together with colleagues from the Domaine Universitaire in France, he presents his findings in the December issue of Environmental Science & Technology. Rosman and his collaborators studied the amounts of four different lead isotopes present in the 2,000-year-old ice. Measurements were very difficult to make as lead concentrations were in the range of one picogram per gram of ice. The result is an unmistakable "fingerprint" that can be compared to the original sources. "This piece of Greenland ice contains the whole history of human pollution," says Rosman. While other researchers have used isotopes of lead to find out where trade routes ran and to prove the authenticity of ancient finds, he goes one step further in his investigation: The origin of the impurities in the ancient atmosphere is determined.
The ratios of lead isotopes in the ice have shown that the main source of this lead is in Spain. The findings support the importance of these mining areas to the Carthaginians, who controlled them from 535 to 205 BC, and later to the Romans, who took over from 410 BC. Rosman was even able to pinpoint its origin to a specific region: he believes that about 70% of “Greenland” lead comes from the Rio Tinto mining area in southwestern Spain.
"Our work," says Rosman, "proves that human activities, and not natural phenomena, significantly altered the composition of the atmosphere; even in ancient Roman times. Huge amounts of lead were produced as a by-product of smelting sulphide ores to extract silver. In any case, lead was used extensively in Roman times and is therefore also mentioned as a Roman metal. Because it is a corrosion-resistant metal and easy to work with, it has found uses in piping, architecture, and shipbuilding. It was also used as a food preservative and added to wine to stop the fermentation process. Later, the high toxicity became a he alth problem." Rosman even wonders how these issues "could have contributed to the fall of the Roman Empire."
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