Topline
Poorly monitored and often illegal small-scale gold mines have released “devastating” levels of toxic mercury in one of the most protected and biodiverse areas of the Amazon rainforest, threatening human health and hampering attempts to conserve fragile tropical ecosystems, according to a study published Friday in Nature Communications.
A chemically deforested area of the Amazon jungle caused by illegal mining activities in the Madre … [+]
CRIS BOURONCLE/AFP via Getty Images
Key Facts
Researchers from institutions in the United States, Canada and Peru found unexpectedly high quantities of mercury in the Peruvian Amazon’s trees and in the tail feathers of songbirds, which can suffer from impaired singing and navigation ability, reduced reproductive ability and increased chance of death if they’re exposed to mercury.
Testing in Peruvian Amazon regions targeted by small-scale gold mining found that soil and tree leaves retained more mercury—which is deposited via rainfall—in places with full forest canopy than in deforested areas.
The atmosphere near some Amazon mining sites—which are often unsanctioned and difficult to monitor—had a background mercury concentration of about 10.9 nanograms per cubic meter, similar to or higher than in urban and industrial areas in the United States, China and South Korea.
Peru’s Madre de Dios region, where illegal gold mining is common, was declared the site of a “chronic mercury epidemic” in 2016 after 40% of people tested in 97 villages showed dangerously high levels of mercury, a problem usually attributed to eating fish.
Researchers suggested small-scale gold mining be formalized and regulated to ensure that it does not take place in national reserves and their surrounding buffer zones.
Surprising Fact
Small-scale gold mining is the world’s largest source of mercury pollution, greater even than coal combustion, researchers said.
Key Background
Small-scale gold miners use mercury to retrieve tiny particles of gold mixed in with soil. After the mercury and gold combine, the gold is extracted by vaporizing the mercury. The element then enters the atmosphere and is passed up the food chain from one organism to another, sometimes accumulating in high quantities in predatory fish like shark, swordfish and king mackerel. If ingested in sufficient quantities, mercury can cause brain damage, birth defects and other disorders.. In February 2019, then-Peruvian President Martín Vizcarra announced he was suspending civil liberties and dispatching 1,500 police and military officers to Madre de Dios to crack down on illegal gold mining, which has been blamed for deforestation and mercury pollution in the Amazon. By December 2020, illegal gold mining had been reduced by 78% in the Peruvian Amazon, according to the nonprofit Amazon Conservation Association, but over 1,000 hectares of land had still faced new deforestation since the government launched its crackdown.
Further Reading
“Alarming Levels of Mercury Are Found in Old Growth Amazon Forest” (New York Times)
