MODELING MOBILITY AND EFFECTS OF CONTAMINANTS IN WETLANDS

Early efforts at modeling wetland ecosystems were aimed primarily at reflecting biomass or nutrient dynamics. A number of models have been developed for different wetland types, including coastal salt marshes, mangrove wetlands, freshwater marshes, swamps, and riparian wetlands. The early ecosystem models were mostly simple compartment models with linear, constant-coefficient differential equations used to simulate biomass or nutrient dynamics. Practically no contaminant flux was incorporated into these models. With few exceptions, the ecosystems were considered spatially homogeneous. At the same time that the ecosystem models were being developed, considerable effort was given to modeling various wetland processes, such as circulation and sediment transport. Other process-level modeling included plant and animal uptake and elimination of both organic chemicals and heavy metals. The level of detail in these process models, however, has not been applied to most ecosystem models. There has been a recent trend, however, to increase the complexity of ecosystem-level models and to incorporate spatial dynamics. These developments should greatly enhance the ability to simulate contaminant transport and effects in wetlands.