Reconstruction and water purification of submerged macrophytes community in eutrophicated Gehu Lake during summer

In-situ enclosure experiment was conducted in Gehu Lake to investigate the effect of environmental change on growth and purification performance of different single and mixture submerged macrophytes community.Results showed that the average biomass of submerged macrophytes was significant linearly correlated with transparency and water level,which indicated that the growth of submerged macrophytes was highly dependent on the light intensity and water depth.The permanganate index and TN in test area were higher than that in control area except for the test area planting Potamogeton malaianus.Compared with control area,planting Vallisneria spiralis,Ceratophyllum demersum and Ceratophyllum demersum-Elodea nuttallii could removal more than 25% of NH3-N,TP and chlorophyll-a;Compared with water open area,TP removal rate in test area of planting Ceratophyllum demersum-Elodea nuttallii,Vallisneria spiralis-Potamogeton malaianus,Vallisneria spiralis-Elodea nuttallii was 33.5%,20.8% and 9.9% respectively;Chlorophyll-a removal rate in Ceratophyllum demersum-Elodea nuttallii planting area was 41.4%.There is a significantly linear relation between TP and chlorophyll-a,so submerged macrophytes could effectively control the algae growth through the TP removal.The average removal rate of NH3-N,TP and chlorophyll-a in Vallisneria spiralis,Ceratophyllum demersum-Elodea nuttallii community and Vallisneria spiralis-Potamogeton malaianus community were consistence with V-t regression equation.The communities of Ceratophyllum demersum-Elodea nuttallii and Vallisneria spiralis-Potamogeton malaianus which had perfect stability and water purification efficiency were best for the submerged macrophytes community reconstruction.