ABSTRACT
Following reports of field situations in which chemistry of acid coal mine drainage improved upon passage through naturally occuring wetlands, the possibility that man-made wetland systems might provide a low-cost, low-maintenance alternative to chemical treatment of mine drainage led to a considerable amount of interest and research. In this chapter, the authors report the results of a laboratory pilot study in which replicate model wetland systems were subjected to inputs of water at uniform flow rates but differing Fe concentrations. Measurements of hydrologic fluxes, water chemistry, and substrate chemistry were used to evaluate effects of Fe concentration in influent waters on Fe retention within these model wetland systems. Iron retention in model wetlands was not homogeneous but more pronounced near inflow ends, which suggests a progressive removal of Fe as water flows. Microbially mediated Fe oxidation may play an important role in Fe retention and increase the “effective” life of wetlands created for the treatment of acid mine drainage.
