Mercury and mercury isotopes in the environment

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Mercury (Hg) is a globally distributed and highly toxic pollutant.  Although mercury poses proven health risks, much of the natural cycle of mercury is not well understood and new approaches are necessary to better elucidate and quantify Hg sources and transformations in the environment.  Dr. B.A. Bergquist recently demonstrated that the isotopes of Hg undergo a unique isotopic fractionation that provides an indelible fingerprint for directly tracking and understanding Hg cycling in the environment.   This isotopic signature, mass independent fractionation (MIF), is generated when mercury undergoes important chemical transformations in lakes and in the ocean.  Thus far, we show that the MIF preserved in fish tissue can be used to understand sources of Hg in food webs.  Further, MIF in natural samples can be used to estimate the fraction of toxic methylmercury that has been detoxified and released from individual lake habitats to the atmosphere.   However, this is only the beginning of an exciting new approach for studying Hg.  These findings pave the way tracing the mobility and toxicity of the Hg in the environment and will facilitate fingerprinting of the sources of Hg exposure to animals and humans.This grant will fund equipment necessary to utilize Hg isotopic signatures to investigate Hg cycling and bioaccumulation in aquatic ecosystems and to understand Hg sources to the environment.  In order to perform this research, it is necessary to accurately and precisely measure Hg concentrations in a variety of sample types including sediments, natural waters, air, snow, fish tissues, and other biological samples.  The requested equipment, a Hg analyzer system and microwave digestion unit, will allow for the accurate determination of Hg concentrations in a variety of sample types and over a large range in concentrations.