Date of Award
Master of Science
Department of Systems Engineering and Management
Michael L. Shelley, PhD
Constructed wetlands used for storm water treatment accumulate metals primarily in their sediment. This sediment has the potential to produce toxic effects in benthic organisms at some period in time. Bioavailability of metals in sediment is directly linked to pore water metal activity. The mechanisms that influence pore water metal activity are included in physical, chemical, and biological processes. A system dynamics model was developed to represent these processes and the major influences affecting pore water metal activity in a treatment wetland receiving storm water influent. The model structure and behavior was tested and validated using several system dynamics validation techniques. The model was run using the metals Pb, Cu, and Cd. The model indicated that the chemical processes of acid-volatile sulfide (AVS) and organic carbon in binding metal in reduced sediment were the greatest influences in controlling metal bioavailability. The effect of bioturbation, as represented in the model, was negligible. Amount of organic carbon in the sediment seems to play the greatest role in controlling metal bioavailability in the long run. This model provides a platform for guiding future research in sediment toxicology, specifically in treatment wetlands.
DTIC Accession Number
Wood, Timothy S., "A System Dynamics model of the Bioavailability of Metals in Constructed Wetland Sediment" (1997). Theses and Dissertations. 5792.