Quicksilver and Gold: Mercury Pollution from Artisanal and Small-Scale Gold Mining

More mercury is used for ASGM—an estimated 1,400 metric tons in 2011—than for any other use of the metal.⁵ The ASGM industry emits an estimated annual average of 1,000 metric tons of inorganic mercury, about one-third of which is thought to go into the air while the rest winds up in piles of mining waste (“tailings”), soils, and waterways.⁷ Some of the inorganic mercury that reaches aquatic ecosystems also gets converted by microbes into organic methylmercury, which accumulates in fish.
http://ehp.niehs.nih.gov/120-a424/