Abstract
The native species, Carex dispalata, Carex thunbergii and Phalaris arundinacea, whose height does not obstruct the View, were compared with Phragmites australis for their adaptability to polluted water and their water purification capability. The results show a stable growing condition of Carex dispalata even in water with a relatively high pollution load. Although the TN values indicate that the purification capability of Carex dispalata is about 70% of the capability of Phragmites australis, the results also suggest nitrification to the root system caused by oxygen supply. The values of TP, COD, BOD show that the removal speed of Carex dispalata and Phragmites australis is about the same. Also the seasonal fluctuation of the contents of nitrogen and phosphorus, which are fixed in the above-the-ground part of Carex dispalata, is small, suggesting that the plants tend to retain these nutrients in the part rather than transporting them to the rhizomes. Therefore, it became clear that we can expect the water purification capability of Carex dispalata in water with a relatively high pollution load, and that it is a useful species for landscape creation and maintenance.
