Climate change going berzerk in Artic.
Thread: Climate change going berzerk in Artic.


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Another NIST article:

Eggs Show Arctic Mercury Cycling May Be Linked to Ice Cover

Overall mercury levels in northern environments have been documented for some 20 years.

Ultraviolet radiation from sunlight can fractionate mercury on the ocean surface via a process known as photodegradation. Laboratory research has shown that this reaction preferentially selects for some isotopes of mercury to move into the atmosphere while others become more abundant in the ocean. Plankton absorb the water-borne mercury, fish eat the plankton, and finally, sea birds eat the fish and pass the ingested mercury into their eggs. Therefore, the eggs are key tissues for mercury monitoring. For the current study, field groups made up of biologists and native Alaskans (for whom seabird eggs are a food source) collected eggs laid by murres, a bird species that nests year-round in three coastal regions of Alaska.

Examination of murre eggs from the northernmost nesting areas where sea ice exists all year long revealed lower amounts of MIF mercury isotopes than in eggs collected from sites in southern Alaska where there is no ice cover. Conversely, the mercury in eggs from nests near ice-free seas reflected significantly greater effects of mass-independent fractionation. The researchers believe that ice prevents UV light from reaching the mercury, effectively suppressing photodegradation.

With the potential for global warming to dramatically reduce Arctic sea ice in the future, the relationship between ice cover and distribution of mercury in the environment is obviously an important one to investigate further. The international research team next plans to use its seabird egg isotope monitoring system to distinguish the sources of mercury contamination in coastal areas to those from oceanic waters. For this study, eggs will be collected along Alaska's Norton Sound that receives runoff from the Yukon River—including high concentrations of cinnabar, the ore from which mercury is derived—and compared to eggs from remote island colonies that are more influenced by atmospheric and oceanic mercury sources.

full article link:
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