According to the Lindberg team, the new findings may help explain why mercury levels in Arctic seabirds, seals and beluga whales have increased over the last few decades, even though global atmospheric emissions of mercury have declined during the last 20 years.
The Alaska study also shows that some of the mercury has the potential to be transformed by bacteria, an indication that this mercury may enter polar food webs.
The mercury sunrise depends on ultraviolet light, open water and active sea ice, all of which have been increasing in Polar Regions over the last few decades. According to the Barrow data, the polar sunrise triggers a series of chemical reactions that convert the elemental mercury vapor into a highly soluble form of oxidized gaseous mercury that rapidly accumulates in the polar snowpack.
Fossil-fuel combustion releases about 6,500 tons of mercury into the atmosphere every year. This mercury vapor remains in the air, where it is carried to all parts of the globe, including the remote polar environments. Ebinghaus and Lindberg agree that mercury sunrises probably occur to some extent throughout polar coastal regions. They estimate that between 50 and 300 tons of mercury are being dumped from the atmosphere into these polar environments annually.