An international research team working with National Institute of Standards and Technology (NIST) scientists at the Hollings Marine Laboratory (HML) in Charleston, S.C., has suggested for the first time that mercury cycling in the flora and fauna of the Arctic may be linked to the amount of ice cover present. Their study* is the latest work reported from the Seabird Tissue Archival and Monitoring Project (STAMP), a multiyear joint effort of NIST, the U.S. Fish and Wildlife Service (USFWS), the U.S. Geological Survey (USGS) and the Bureau of Indian Affairs to track trends in pollutants in northern marine environments using seabird eggs.
Overall mercury levels in northern environments have been documented for some 20 years. However, the new study marks the first time that the tracking has been done using a sophisticated analysis of mercury isotopes (forms of the same atom that have different atomic masses) and an effect called "mass-independent fractionation" or MIF.
MIF is a relatively unusual change in the relative abundance of different isotopes of the same element (fractionation) that can be the result of photochemical reactions. Determining the relative amount of the MIF isotopes of mercury is considered valuable because the data can be used to trace the reactions in nature that led to the fractionationand in turn, provide a better understanding of how the reactions work and how they impact the cycling of mercury in the environment.
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
|Contact: Michael E. Newman|
National Institute of Standards and Technology (NIST)