植物光合特性及其对湿地DO分布、净化效果的影响

为了研究人工湿地中植物的光合特性及其对湿地系统中溶解氧(DO)分布和污染物净化效果的影响,通过中试试验考察了芦苇、美人蕉、空心菜、富贵竹等几种典型湿地植物的光合作用特性及其与湿地DO分布、污染物去除效果之间的关系,藉此优选湿地植物,改善DO分布,强化脱氮效果.结果表明,植物净光合速率(Pn)对DO分布影响显著,湿地中段DO浓度高于两端,证明了植物对湿地系统存在供氧作用,其中芦苇产氧输氧能力最强,为湿地首选植物;此外,Pn还与湿地TN、NH4 -N去除效果显著相关.因此,可通过优选光合产氧输氧能力强的植物或采用适当增加种植密度等方式加强供氧以强化脱氮效果.

Influence of plant photosynthetic characteristics on DO distribution, purification effect in constructed wetlands

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.