August 12, 2015

Better estimates of worldwide mercury pollution

New findings show Asia produces twice as much mercury emissions as previously thought.

(August 12, 2015) 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 has conducted a new analysis that provides more accurate estimates of sources of mercury emissions around the world. The analysis pairs measured air concentrations of mercury with a global simulation to calculate the fraction of mercury that is either re-emitted or that originates from power plants and other anthropogenic activities. The result of this work, researchers say, could improve estimates of mercury pollution, and help refine pollution-control strategies around the world.

The new analysis shows that Asia now releases a surprisingly large amount of anthropogenic mercury. While its increased burning of coal was known to exacerbate mercury emissions and air pollution, the MIT team estimates that Asia produces more than double the mercury emissions previously estimated.

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