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

The recent development of sensitive analytical techniques for the dete rmination of MeHg concentrations in water has resulted in a rapid adva ncement in our understanding of MeHg production and transport in lake and reservoir systems. Results from three recent whole-ecosystem studi es have shown that there ard three important sources of MeHg to aquati c systems - precipitation, runoff from wetlands, and inlake methylatio n. 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 o f wetlands in the terrestrial catchment and the percentage of water su rface area that covers flooded terrain.