#quelccaya

Pre-Industrial Revolution Pollution

Glacial ice is like a time capsule; it stores a record of what was in the atmosphere at the time the ice was formed. Scientists have used cores from the Quelccaya Ice Cap in the Peruvian Andes to discover that humans started polluting the atmosphere long before the Industrial Revolution.

800 kilometers (500 miles) away from Quelccaya, in what is now Bolivia, the Inca had long refined silver, but in too small of quantities to cause much pollution. Then the Spanish Empire conquered the area. Incas were forced to work in the mines of Potosí on the Cerro Rico mountain, at the time the richest silver-producing area in the world, significantly boosting mining activity.

In 1572, the Spanish further increased production by introducing a new process to extract silver from the lead-rich ore. It required grinding the ore into a powder, and since there was significantly more lead than silver, the result was large quantities of lead dust being released into the atmosphere, along with smaller quantities of arsenic, antimony, bismuth, and molybdenum.

The Quelccaya Ice Cap is well-situated for tracking pollutants; winds bring dust to the mountain where it gets trapped under snow that eventually turns into glacial ice. Researchers analyzed the chemicals in the ice cores going back in time to 800 C.E. They found much higher concentration of lead along with the other elements starting around the same time that the new refining process was introduced. It didn’t taper off until the 1800s when Bolivia and other South American countries declared their independence.

The team verified that the pollutants came from Potosí by comparing the chemical signatures to other data sets closer to known pollution sources. This included sedimentary lake records near Cerro Rico. Samples from those sites showed that other mines contributed pollution as well, but not as much as the much larger Potosí mines.

Of course this early pollution is nowhere near as abundant as what’s been released since the Industrial Revolution. The scientists noted that the ice containing the mine pollution still appeared to be perfectly clean ice. Even so, they note that it must have been a considerable source of pollution to travel those 800 kilometers and affect the chemistry of Quelccaya’s snow.

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Photo Credit: Edubucher http://bit.ly/1FtHshM