Remobilization Of Cobalt, Copper, Nickel, Lead, And Zinc In A Riparian Wetland Model

The mobility of chemically persistent metals in riparian wetland systems that could have a detrimental impact on the environment is an area of active research. This study utilized a physical model consisting of open water and wetland cells designed to simulate a natural riparian wetland to examine the mobility of five metals. The objective of the study was to determine if riparian wetlands have the potential to serve as permanent sinks for metals, or if they only serve as temporary sinks and with time metals could be remobilized and released. Specifically, this study examined the long-term behavior of Co, Cu, Ni, Pb, and Zn in a compressed time frame of 48 weeks by accelerating processes such as decomposition, inundation cycles, and sediment and cypress litter deposition that would occur naturally over a longer time scale. Concentrations of these metals, as well as ORP, were monitored throughout the study in both cells of the model. The results of this study show that the environmental conditions in the model allofor clear, observable remobilization of Co, Cu, Ni, and Pb. However, mobilization was primarily limited to the wetland cell and significant migration of metals to the adjacent open water cell was not observed. It is suggested that the mobilization of these metals occurred under reducing conditions where the dissolution of Fe and Mn-oxyhydroxides would have favored the release of metals previously adsorbed to these phases