Fig. 1. Pore water Cr(VI) concentrations: (A) after 6 mo of operation; and (B) after 11 mo of operation. The Phragmites australis (without acetate) microcosm was only sampled once after 6 mo of operation. Lines represent nonlinear regression curves of the concentrations against depth. Chromium(VI) removal rates were calculated based on the regression curves to minimize the effects of experimental variations.