Comparison on purification capacity of soil nitrogen and phosphorus in different wetland plants

Wetland plants are very important component of wetlands;these plants are necessary for the degradation of pollutants and water/soil purification.In this paper,three aquatic plants(i.e.Iris wilsonii,Nymphaea tetragona,and Phragmites australiss) were chosen to compare the diversity on nutrition absorption and soil nitrogen and phosphorus purification capacity based on field control test.The results showed that net accumulated biomass varied intensively among different wetland plants,which ranged from 12.81 to 119.43g m-2,with the highest biomass of Iris wilsonii and lowest of Phragmites australiss.Besides,the absorption rate of nitrogen and phosphorus in the above vegetations changed from 23.96%～41.86% and 2.18%～12.73% respectively with the highest uptake ratio of Nymphaea tetragona.Furthermore,obvious discrepancy(i.e.12.20%～45.28% and 33.30%～52.56% respectively) was calculated in soil nitrogen and phosphorus decomposition ratio under different wetland plants.Consequently Iris wilsonii was having the highest calculated decomposition ratio of soil nitrogen and phosphorus.Similarly Phragmites australiss was having the lowest decomposition ratio of soil nitrogen,whereas Nymphaea tetragona was found lowest in the decomposition ratio of soil phosphorus.Overall,the removal of soil phosphorus from three plants was found superior to that of soil nitrogen.Therefore,species with higher removal ratio would be considered superior in the use of purification capacity.In addition,the higher percent of nitrogen and phosphorus in the ground surface plants seemed better for removing them when reaping,which was beneficial for purification to some extent.Moreover,it is useful to reveal the purification mechanism of surplus nutrient from wetland plants,and provide scientific reference for wetland restoration and plant screening projects,which is also significant for wetland protection and restoration.