Influence Of Water Levels And PH On The Common Emergent Plants

With the development of the society, the status of eutrophic water is very severe: eutrophieation degree intensifies continuously, and the radio of eutrophic water increases every year. Due to low investment, running cost, easy maintenance and management, the artificial wetland is often considered to be effective means for the prevention and control of eutrophieation. At present, the numbers of the study on the effect of different wetland plants for water purification are large, but the research about the suitability of the wetland plants on the wetland environment and the study of water purifying effect are relatively small. Therefore, under the condition of different water level and pH, this paper was analyzing and comparing purifying effect of three kinds of common emergent plants, Acorus calamus Linn, Iris pseudoacorus, Canna indica, by laboratory simulation experiments. And then the purifying mechanism on nitrogen and phosphorus of Iris pseudoacorus was discussed. The main conclusions were as follows.(1) As the increasing water level, the purifying capacity of the three kinds of plants was improving.(2) The purifying capacity of TN、TP and NH3-N of the three kinds of plants was stronger in the acidic and neutral water than in the alkaline water. Under the condition of the alkaline water, the concentration of HPO2-4 was highest than the others.(3) Compared the change of the four seasons of nitrogen and phosphorus in water, the purification effect of them was different in different seasons. Nitrogen and phosphorus removal rate of three kinds of plants was about 100% in summer,80%～90% in autumn,50%～70% in spring, and under 50% in winter. Ammonium concentration was about O.Olmg/L in late summer, about 0.03mg/L in late spring and autumn, and about 0.06mg/L in late winter. The content of phosphate in the water of late spring, summer and autumn was lower than it in late winter. This showed that there was a certain relationship with purification effect and seasons, so it was necessary to take seasonal fluctuations into account when we chose the plants.(4) In summer, the primary mean on TN and TP removal of Iris pseudoacorus in the water was plant storage, while it was microbial action in winter. In summer, the contributin rates for TN revoral were plant storage (63.23%), microbial action (17.18%), and plant metabolism (14.02%). The contributin rates for TP revoral were plant storage (79.36%), microbial action (12.24%), and plant metabolism (8.22%). In winter, the contributin rates for TN revoral were microorganism in natural water (62.59%), increased microorganism due to existence of plant (13.36%), and plant direct action (17.78%). the contributin rates for TP revoral were microorganism in natural water (29.22%), increased microorganism due to existence of plant(51.19%), and plant direct action(21.45%).