Many people still associate mercury with thermometers and most also know that it is toxic. Because of its toxicity, mercury is on its way out from products in Europe but a lot of it is still circulating in air, water, soil and ecosystems.
The legacy of the human use of mercury has resulted in hundreds of thousands of tonnes of mercury being released into the environment. The levels of mercury in the atmosphere at the moment are up to 500 % above natural levels. In the oceans, the concentrations of mercury are about 200 % above natural levels.