Man already contributed to lead poisoning 8,000 years ago. Scientists from the University of Pittsburgh on the upper peninsula of Michigan. There, the team found the oldest remains of man-made metal pollution.
The discovery suggests that this pollution caused by mining, among other things, already existed much earlier in North America than in Europe, Asia and South America. The team came to the result by taking sediments from the lake. "Our findings show the influence of former Indians on the living environment," says David Pompeani, lead author of the research.
The Michigan Peninsula is the largest source of pure copper in North America: the ideal place for the team's research. Earlier, in the 1800s, scientists discovered evidence for prehistoric mining. They found tools such as hammers, ladders and grooves.
In June 2010, the team started collecting sediments on the peninsula. They did this at three lakes, all of which were near old quarries. They then analyzed the concentration of lead, titanium, magnesium, iron and organic matter. They also looked at increases in lead pollution thousands of years ago. “The results show that certain amounts of lead have been emitted by pre-agricultural peoples. They already started mining around 8000 years ago ". According to Pompeani, it is the first time that it can be proven that prehistoric pollution in the copper areas of Michigan can be detected in sediments from the lakes. This is in contrast to reconstructions of metal pollution in other parts of the world. These only provide evidence for lead pollution during the past 3000 years.
The researchers are now investigating other lakes near copper mines.