Air Pollution from 16th-century discovered in Peru’s Ice


Deep inside an ice cap in the Peruvian Andes, scientists have traced air pollution from 16th-century Spanish silver mines. In an announcement made on Monday, scientists said the pollution appeared to have originated from what is now called Bolivia, located hundreds of miles away at the Potosí mountaintop silver mines. The imprint of metal-rich smog was actually discovered in Peru.

Designated as a UNESCO World Heritage site, Potosí is located at an altitude of about 13,120 feet. Efforts were being diligently made by the Inca people to extract and refine silver from Potosí for generations before the Spanish arrived.

A boom was witnessed in the mining activity during the colonial period, and Potosí was confirmed to be the largest source of silver in the world.

About 160,000 colonists had been living in Potosí alongside about 13,500 indigenous people by the 17th century. Amalgamation, a new technology introduced by the Spanish in 1572 to expedite the process of silver production, was the key to the success of the mines. The process involved grinding of lead-rich silver ore into powder and mixing it with mercury.

Release of thick clouds of lead-laden dust into the atmosphere had taken place during milling. Researchers extracted a long ice core from the Quelccaya Ice Cap in 2003 to conduct a study on the climatic changes in South America during the past 2,000 years. They missed on a section of the ice ore from the colonial era that was stained with soot.

After chemical analysis, the researchers discovered that the Quelccaya began catching much larger quantities of metals, especially lead, just before 1600.

“The metallurgic activities of the Inca had most likely only a local impact on the environment surrounding their mining operations,” said Paolo Gabrielli, a study author and research scientist at the Byrd Polar and Climate Research Center at Ohio State.

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