Illicit Gold Mines Destroying Peruvian Rainforest

The average annual rate of forest loss has tripled since 2008, when the price of gold soared.

Environmental News Service reported Oct. 28 that the Madre De Dios region of the Peruvian Amazon Rainforest is being decimated by small, illicit gold mines. The gold mines grew from the 2008 financial crisis, which caused gold prices to soar and clandestine mines to proliferate in the low-lying southeastern region of Peru.

Researchers from the Carnegie Institution, in collaboration with officials from the Peruvian Ministry of Environment, mapped the true extent of gold mining by combining information from field surveys with airborne mapping and high-resolution satellite monitoring. The maps show that the average annual rate of forest loss has tripled since 2008, when the price of gold soared.

The research team used the Carnegie Landsat Analysis System-lite, known as CLASlite, to detect and map both large and small mining operations. CLASlite uses algorithms to detect changes to the forest in areas as small as 10 square meters, about 100 square feet, allowing scientists to find small-scale disturbances that cannot be detected by traditional satellite methods.

The team supported the satellite results with on-ground field surveys and data from the Carnegie Airborne Observatory (CAO).  CAO uses Light Detection and Ranging, or LiDAR, a technology that sweeps laser light across the vegetation canopy to image it in 3-D. It can pinpoint the location of single standing trees at 3.5 feet (1.1 meter) resolution. The field and CAO data confirmed up to 94 percent of the CLASlite mine detections.

In addition to damaging tropical forests, gold mining releases toxic sediment into rivers, with severe effects on aquatic life. Other recent research has shown that Peru's gold mining has contributed to widespread mercury pollution, which affects the entire food chain, including the food ingested by people throughout the region.

The results of this research are published in the online early edition of the journal "Proceedings of the National Academy of Sciences" for the week of Oct. 28, 2013.