Andean ice core reveals air pollution before Industrial Revolution

Science : The Quelccaya Ice Cap in Peru serves as a record of the tropical region’s wet and dry seasons, which can be easily traced in the alternating layers of clean and dusty snow compacted in the glacier. A study of ice cores by Paolo Gabrielli of the Ohio State University and his colleagues has also revealed details about air pollution in the region over time. Around 1400 CE, the Incas began mining and smelting silver, which released lead and other materials into the atmosphere. Gabrielli’s team found that, between 1450 and 1900, levels of lead in the ice cores doubled and concentrations of antimony increased 3.5 times. The researchers believe the largest contributor was the Potosí silver mine operated by the Spanish, who came to South America in the 16th century. Air pollution decreased slightly during the 1800s, perhaps due to the South American wars of independence and the economic downturns that accompanied them. However, pollution levels increased drastically between 1900 and 1989 as mining expanded to copper and molybdenum and the number of automobiles multiplied. In that period, silver levels in the ice cores tripled, copper and lead levels doubled, and molybdenum levels increased more than twofold.