Gold Mining and the Environment

As much as two grams of mercury can be released into the environment for every gram of gold recovered. The mercury often enters river basins, spreading the mercury across national borders and into larger bodies of water. It is estimated that the Amazon basin receives 40 tons of mercury a year, while mining in Indonesia adds 150 tons to the Java Sea annually.
In March of 2008, an investigation into mercury emissions led to a state-ordered shutdown of the processing plant of a major gold mine in northeastern Nevada. Mercury from Jerritt Canyon and other gold mines in the state has contaminated lakes across the region.

Mercury vapor has serious health consequences for animals and humans. The amount of vapor released by mining activities has been proven to damage the kidneys, liver, brain, heart, lungs, colon and immune system. Chronic exposure to mercury may result in fatigue, weight loss, tremors, and behavioral and personality shifts.
http://www.brilliantearth.com/gold-mining-environment/