Modeling Mobility and Effects of Contaminants in Wetlands

Abstract

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.

Drag, turbulence, and diffusion in flow through emergent vegetation

“…Freshwater and saltwater wetlands provide important transition zones between terrestrial and aquatic systems, mediating exchanges of sediment [Phillips, 1989], nutrients [Nixon, 1980;Barko et al, 1991], metals [Orson et al, 1992;Lee et al, 1991], and other contaminants [Dixon and Florian, 1993]. Wetland plants control these exchanges both directly through uptake and biological transformation and indirectly by altering the hydrodynamic conditions [Kadlec, 1995].…”

DNA-labeled clay: A sensitive new method for tracing particle transport

“…The processes controlling movement and transport of particulates are of great interest to earth scientists working in a range of environments. Migration and storage of contaminantladen sediments in wetlands (Dixon and Florian, 1993;Johns, 1995), colloidal and particle-associated contaminant transport through fractured and karst aquifers (Reimus et al, 1996;Mahler, 1997), erosion of soil from agricultural lands (Whitmore et al, 1997;Lobb and Kachanoski, 1997), and atmospheric transport of particulates (Beceiro-Gonzalez et al, 1997;Sandroni and Migon, 1997) are but a few examples of current research topics. Sediment-transport processes, far more complex than those of fluid flow, remain poorly understood, and models of these processes often do not adequately describe particle movement in the field.…”

Numerical Modeling of the Interactions Between Nonlinear Waves and Arbitrarily Flexible Vegetation

“…Aquatic marshes are ubiquitous at the land-water interface and are known to have significant effects on the hydrodynamics (Chen et al, 2007), sediment processes (Neumeier and Ciavola, 2004), and nutrient (Barko et al, 1991) and contaminant (Dixon and Florian, 1993) exchange. In addition, observations have documented the dissipative effect of vegetation on surface waves, suggesting that wetlands can mitigate damages to the upland.…”