SOURCES OF METHYL MERCURY TO FRESH-WATER ECOSYSTEMS - A REVIEW

The recent development of sensitive analytical techniques for the determination of MeHg concentrations in water has resulted in a rapid advancement in our understanding of MeHg production and transport in lake and reservoir systems. Results from three recent whole-ecosystem studies have shown that there ard three important sources of MeHg to aquatic systems - precipitation, runoff from wetlands, and inlake methylation. Data from these three studies are used to construct a simple model that illustrates how the relative importance of these sources can vary with rates of atmospheric deposition of MeHg, lake type, percentage of wetlands in the terrestrial catchment and the percentage of water surface area that covers flooded terrain.