2. Materials and methods
2.1. Experimental setup
The IVCW microcosms were located near Donghu lake of Wuhan
city, China. Two parallel pilot-scale IVCWs, each with a downflow
chamber (1 m×1 m×1 m) in series with an up-flow chamber(1 m×1 m×1 m) (Fig. 1), were constructed in the field. Gravel of 10–20 mm diameter in size was filled to a depth of 50 cm and 40 cm
for the down-flow chamber and up-flow chamber, respectively,
followed by a 35 cm thick layer of 2–10 mm diameter gravel. The
porosity of the substrate was 0.40 and the effective volume of the
wetland bed was 0.6 m3.
Four species of macrophytes, C. indica (Canna L.), P. cordata
(Pontederia L.), T. orientalis (cattail), A. donax var. versicolor (A.
donax) were employed in the study. Cattail and A. donax were
transplanted to the down-flow and up-flow chambers of Plot 1,
respectively, at a density of 9 plants/m2. Similarly, canna and Pontederia
were transplanted to Plot 2.