Influence of plant photosynthetic characteristics on DO distribution, purification effect in constructed wetlands
植物光合特性及其对湿地DO分布、净化效果的影响

The aim of this study is to investigate the plant photosynthetic characteristic and its influence on the distribution of dissolved oxygen (DO) and removal efficiency of pollutants in constructed wetlands. The photosynthetic characteristics of several typical plant species, such as Reed, Canna, Ipomoea and Dracaena were measured. Besides, the relationship between net photosynthesis rate (Pn) and DO distribution as well as the pollutant removal effect in constructed wetlands were investigated. Therefore, most appropriate plants were selected out and then the DO condition would be improved. Thus the nitrogen removal effect could be enhanced. Results indicated that Pn had distinct effect on the DO distribution, and the DO concentration in the midst of wetland was higher than that in ends. Accordingly, the oxygen supply capability of plants was verified and reed was the preferred plant in present study, particularly demonstrating stronger oxygen supply capability. Results also showed that Pn was remarkably related with the removal effect of TN and NH~+_ 4 -N. As a result, oxygen supply could be strengthened to enhance nitrogen removal effect by means of selecting plants with strong oxygen supply capacity or appropriately increasing planting density.