MODELING MOBILITY AND EFFECTS OF CONTAMINANTS IN WETLANDS

Early efforts at modeling wetland ecosystems were aimed primarily at r eflecting biomass or nutrient dynamics. A number of models have been d eveloped 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 b iomass or nutrient dynamics. Practically no contaminant flux was incor porated into these models. With few exceptions, the ecosystems were co nsidered spatially homogeneous. At the same time that the ecosystem mo dels were being developed, considerable effort was given to modeling v arious wetland processes, such as circulation and sediment transport. Other process-level modeling included plant and animal uptake and elim ination of both organic chemicals and heavy metals. The level of detai l in these process models, however, has not been applied to most ecosy stem models. There has been a recent trend, however, to increase the c omplexity of ecosystem-level models and to incorporate spatial dynamic s. These developments should greatly enhance the ability to simulate c ontaminant transport and effects in wetlands.