Mercury in Fish

Photo_ArealViewMesosResizedElevated levels of methyl-mercury (Hg), a potent neurotoxin, in fish are found in many lakes worldwide. As part of my Master’s thesis, I produced the first experimental evidence of a direct link between the loading rate of inorganic mercury (Hg) to freshwater ecosystems and the amount of methyl-Hg bioaccumulated by fish. The findings of my study were significant because, at the time, it was not clear whether proposals to reduce Hg emissions from coal-fired power plants would lower methyl-Hg levels in fish.

To better understand the effects of Hg emission reductions, I simulated different rates of atmospheric Hg deposition in large, in-lake mesocosms at the Experimental Lakes Area, Ontario. I added inorganic Hg highly enriched with a stable isotope, which allowed me to track its environmental fate and bioaccumulation. The added Hg was quickly converted to methyl-Hg and incorporated into all levels of the food web, with concentrations of methyl-Hg in the environment and fish in direct proportion to the loading rate of inorganic Hg.

My Master’s research generated four peer-reviewed publications, including two in the high-impact journal Environmental Science & Technology. One of these publications was selected for a special news feature. These papers have been highly cited, receiving a total of 118 scholarly citations, and were referenced in the U.S. Federal Register for the development of new Hg emission standards.


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