Environmental News Network: Once mercury is emitted into the atmosphere from the smokestacks of power plants, the pollutant has a complicated trajectory; even after it settles onto land and sinks into oceans, mercury can be re-emitted back into the atmosphere repeatedly. This so-called grasshopper effect keeps the highly toxic substance circulating as legacy emissions that, combined with new smokestack emissions, can extend the environmental effects of mercury for decades. Now an international team led by MIT researchers...