Field studies were undertaken on both a wetland, which is downgrabient from a radioactive waste storage area at Chalk River Laboratory, and a grassland near Pickering nuclear power station. The purpose for this study was to quantify HTO (tritiated water/vapor) transfer in the land surface environment. The amounts of evaporation and transpiration were separately estimated, because the specific activity of tritium (HTO) is commonly different between surface and subsurface soil. Most of the water and tritium fluxes are attributed to transpiration in the season examined. Measured tritium concentrations in leaves at daytime agreed with predicted values, which are based on a simple equation. The ratios of organically bound tritium (OBT) to free water tritium ranged from 0.2 to 0.8 in this study.