It was not only modern people who polluted the atmosphere. 2.000 years ago, the Romans melted precious metals in earth quarries, so they were getting silver and spraying the lead smoke into the sky.
Some of this bullet hit the Greenland glaciers and blended into the layers of ice that accumulated without stopping. Nowadays, scientists studying the annual sediments of these ice layers reveal that the ups and downs of lead pollution during the Roman period shed light on the timing of many historical events, including the wars that Julius Caesar made.
Dennis Kehoe, an academic at the University of New Orleans, Tulane University in the field of Roman economic history and law, says the level of detail in the ice is "amazing". What really affected Kehoe was that the values of lead pollution closely corresponded with what he had known about the development and collapse of the Roman economy based on silver coins known as the denarius of ancient historians. Kehoe said, "Indeed, this is a rise and a collapse of a monetary system based on silver. Prices were indexed to silver, so silver was a must for them. "
Scientists have had information about the increase of lead pollution in the Roman period since the 1990s. In those years, researchers measured lead levels from a few places, from the length of ice cores extracted from Greenland's ice sheets, each measurement corresponding to a two-year period. Subsequent investigations confirmed the same situation in soil samples taken from peat marshes in Spain, Scotland and the Faroe Islands.
An archaeologist from Oxford University and a Romanologist Andrew Wilson formed a team with ice nucleus experts to get a clearer picture of what was happening. The team measures the level of lead pollution on a roughly 400-meter cross-section from the glaciers of Greenland's 1100 to 800-degree ice-cold layers. The ice layer was gradually melted from one end to the other, the dissolved ice was taken to be analyzed, and about 12 measurements were obtained annually during the Roman period. The investigations revealed that all the lead in the ice did not come from the pollution that occurred in the melting process of mines, and that some of them were related to the naturally occurring emissions of dust and volcanoes that the researchers estimated and calculated from the total lead count.
The results were published in a scientific review of the 1900-year timeline of the incredibly detailed Roman lead pollution, Proceedings of the National Academy of Sciences . Lead pollution was the highest level in the 1st century AD, when the Roman Empire was at its peak. It was roughly six times higher than it was in the 11th century. However, after the appearance of the Antonine Evas, which caused millions of deaths, in 165 BC, the lead pollution suddenly fell to the pre-Roman level and stayed there for 500 years. In the mid-Roman era, especially during the last few centuries BC, when war broke out in Spain, which is an important point in lead-silver melting, the level of lead pollution decreased.
The team, based on air circulation schemes, suggested that the Roman empire, largely from the western, eastern and western Europe, suffered from the Roman accumulation of lead accumulating less than one billionth of a meter of grams a year. In comparison, Joe McConnell, environmental scientist and research editor at the Desert Research Institute in Reno, Nevada, says that the amount of lead in Greenland is roughly 50 times lower than in 1900.
The ancient historian Kevin Butcher of the University of Warwick, England, says that his work brings "many interesting questions" to minds. There are a few confusing points of lead pollution and incompatibility between the highest levels of silver coin production. Is the Romans melting silver or wondering if they were storing it without converting it to a coin? According to Butcher, the information obtained is "thought provoking".
Science Mag. 14 May 2018.