16th Century Air Pollution Discovered Frozen in Peru's Ice from Spanish Conquistadors

When did air pollution first appear in South America? Apparently, it was present even during the 16^th century. Researchers have discovered remnants of air pollution in the Quelccaya Ice Cap, revealing a bit more about the past history of the region.

In the 16^th century, during its conquest of South America, the Spanish Empire forced Incas to work extracting silver from the mountaintop mines of what is now Bolivia; at the time, it was the largest source of silver in the world. In 1572, the Spanish introduced a new technology that boosted production and sent thick clouds of lead dust over the Andes and northwest into Peru, where it then settled on the ice cap.

The researchers took cores of the Quelccaya Ice Cap and examined them using a mass spectrometer. This allowed them to measure the amount and type of chemicals present in the ice dating back to 800 AD. More specifically, the researchers looked for antimony, arsenic, bismuth, molybdenum and lead, which are involved in the refining process.

"This evidence supports the idea that human impact on the environment was widespread even before the industrial revolution," said Paolo Gabrielli, one of the researchers, in a news release.

The researchers found that there were spikes in the concentrations of these elements before Spanish rule, but that these layers are likely part of natural contamination sources, such as volcanic eruptions. Just before 1600, though, the researchers found even higher concentrations, and the high amounts persisted until the early 1800s, which is when South American countries declared independence from Spain.

"The fact that we can detect pollution in ice from a pristine high altitude location is indicative of the continental significance of this deposition," said Gabrielli. "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 reveal a bit more about the history of the region and its pollution. It also shows that human-made pollution can spread across vast distances and impact areas far removed from the initial source.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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