China needs to get to grips with its gold mining pollution crisis

If you use mercury, you amalgamate the gold with the mercury and then burn it off, and so the mercury will deposit itself somewhere within the ecosystem. Mercury is what we call biopersistent – it gets eaten up by organisms and then stays in the environment for a very long time. And it’s a neurotoxin, so you don’t see the impact right away. It actually has a much more insidious impact over many years. Mercury pollution across China is widely documented.
With cyanide, it’s different. Cyanide has an immediate impact, but it’s not biopersistent. Cyanide can actually decompose in sunlight. So you can get a sudden fish kill from a cyanide spill but it doesn’t have the long-term persistent impact that mercury might have.
https://www.chinadialogue.net/article/show/single/en/6996-China-needs-to-get-to-grips-with-its-gold-mining-pollution-crisis