Researchers discovered the earliest-known evidence of man-made pollution in South America buried in the Peruvian Quelccaya Ice Cap.
In the 16th century, the Spanish empire took over South America and forced Incas to work in silver mines located at the tops of mountains, The Ohio State University reported. Some of pollution from the thick clouds of lead dust caused by the mining was carried 500 miles north to where it was recently discovered by scientists.
The ice core provides the first record of human-induced air pollution in South America before the occurrence of the Industrial Revolution.
"This evidence supports the idea that human impact on the environment was widespread even before the industrial revolution," said Paolo Gabrielli, a research scientist at the Byrd Polar and Climate Research Center at Ohio State and corresponding author of the study.
To make their findings the researchers used a mass spectrometer to measure the types of chemicals present in ice dating as far back as 800 AD. The measurements revealed spikes in concentrations of lead and other substances before the Spanish rule, but these are believed to be related to natural phenomena. Starting around the year 1600 the ice started to capture larger quantities of these elements, and the high levels remained until about 1800 when the South American countries became independent from Spain. The findings line up with what is known about activity in the area from written records.
"The fact that we can detect pollution in ice from a pristine high altitude location is indicative of the continental significance of this deposition," Gabrielli said. "Only a significant source of pollution could travel so far, and affect the chemistry of the snow on a remote place like Quelccaya."
The findings could help us better understand the fate of pollution circulating through our atmosphere today.
The study was published in a recent edition of the Proceedings of the National Academy of Sciences and was funded by the National Science Foundation.
