Mercury Pollution in Mining

For one gram of gold produced artisanal gold miners dumps about two grams of liquid mercury into the environment. Together, the world's 15 to 20 million illegal gold miners release about 2000 tons of mercury into the environment every year, or 45 percent of man-made mercury pollution to the environment. Artisanal gold mining is truly the leading global mercury pollution of caused to the environment, ahead of water power plants.
http://www.world-mining.com/2014/12/mercury-pollution-in-mining.html