Far more atmospheric mercury was deposited on the surface of Antarctic ice during the coldest glacial periods than during warmer times, according to a study online in Nature Geoscience. This suggests that, like today, the polar regions were an important sink for atmospheric mercury.

Paolo Gabrielli and colleagues used state-of-the-art analytical techniques to measure mercury concentrations in ice from the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core. Their reconstruction covered the past 670,000 years, and found that concentrations were highest during the coldest and dustiest intervals. They suggest that the colder temperatures enhanced reactions between dust, airborne sea salts and atmospheric mercury, resulting in the transport of mercury to the snow below.