An environmental simulation model for transport and fate of mercury in small rural catchments

The development of an extensively modified version of the environmental model GLEAMS to simulate fate and transport of mercury in small catchments is presented. Methods for parameter estimation are proposed and in some cases simple relationships for mercury processes are derived. An application is presented for the agricultural organic soils in the South Florida Everglades (USA). Model results compare well with the limited available field observations. Mass balance and sensitivity analyses indicate that atmospheric deposition and reduction leading to evasion are the most important parameters controlling concentrations of total mercury in the upper soil. For methyl mercury, the methylation and demethylation rates are also important. Because of the special characteristics of the soils examined here, results should be interpreted in a relative sense. Limitations and potential uses of the current status of model are discussed.