The proliferation of pits and ponds created in recent years by miners digging for gold in Peru’s Amazon has altered the landscape and amplified the risk of mercury poisoning, a new study shows. In some watersheds, there’s been a 670% increase in land area covered by abandoned mining pits that have filled in with water. Low-oxygen conditions in these ponds accelerate the conversion of submerged mercury, a leftover from the mining, into highly toxic methylmercury.
