Scientists found clear traces of lead pollution deep within the Peruvian Quelccaya Ice Cap that were dated back in the 16th Century, 200 years before the Industrial Revolution. Researchers speculate that the pollution was caused by the conquistadors that ran silver-mining businesses with help from the natives.
Although, the ice cap was located in the Peruvian Andes, the source of the man-made pollution was in Bolivia, on top of Potosí Mountain, where silver-rich mines had been exploited since ancient times.
UNESCO has already listed Potosí as a World Heritage Site because of its sites rich in industrial artifacts. Historians claim that the Incas had been extracting silver from these mines long before they were invaded by the conquistadors.
However, after the arrival of the Spanish the industry for extracting and refining silver bloomed, turning Potosí into the world’s most important silver provider during the colonial era. Historical records show that by the end of 17th century nearly 160,000 colonists had settled in Potosí.
The economic boom of the site was due to the cheap labor force, since more than 13,000 Incas were used as slaves by the colonists in the silver ore extracting business, and to amalgamation, a special technique employed in the process of ore refining.
Although the technique was highly effective, it was also very polluting. Amalgamation was introduced by the Spanish conquistadors in 1572 to speed up the silver refining process. The silver ore, which was also rich in lead, was ground into a powder, which was later mixed with mercury to separate silver from the rest of the components.
But the grinding process resulted in thick clouds of dust loaded with laden particles, which were released into the atmosphere and carried away by the wind in remote places. Thus, scientists explained, the lead pollution from Potosí imprinted the Peruvian ice cap located 500 miles/ 800 kilometers away.
In 2003, scientists extracted a long ice core from the ice cap to analyze the natural climate change in the region over the past two millennia. With the bare eye, researchers weren’t able to notice the soot polluted area matching the colonial era. But with help from chemical analysis, they found that between 1,600 and the early 1800s the Quelccaya Ice Cap was heavily stained by human-made lead pollution.
In the early 1800s, the silver extracting industry collapsed due to the South American Wars of Independence, according to the findings.
The findings were published Monday in the Proceedings of the National Academy of Sciences.
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