Arctic Sea-Ice Cracks Are a Source of Mercury Pollution

Tiny tempests above cracks in Arctic sea ice help pull down toxic mercury and ozone from the sky — an unexpected new source of mercury pollution in the polar environment, according to research published today in the journal Nature.

Low concentrations of mercury vapor, from sources such as coal-fired power plants and gold mining, pollute the atmosphere everywhere on Earth. The gas can travel thousands of miles from its source, even reaching the North and South poles.

Mercury leaves the atmosphere above the Arctic every spring. About 20 years ago, scientists discovered how it escapes: a strange chemistry triggered by the sun that takes place mainly along coastal areas. When the sun peeks above the horizon after a long, dark winter, the solar rays jump-start chemical reactions that quickly remove mercury and ozone from the lowest layers of the atmosphere. (The ozone destroyed during this process is a pollutant, not the protective ozone in Earth's stratosphere, a layer of the atmosphere above the one humans live in, called the troposphere.) Read more...