Fig. 2. Fluxes of CH₄–C (mg m^–2 d^–1) (mean and standard error of the mean [SE]) from various sections within each examined constructed wetland. (a) and (b) Free surface water (FSW) wetlands; (c) and (d) overland and groundwater flow (OGF) wetlands; (e) and (f) horizontal subsurface flow (HSSF) wetlands; (g) and (h) vertical subsurface flow (VSSF) wetlands for the summer and winter seasons, respectively.