Studies On The Purification Of Aquatic Plants And Its Utilization In Residential Areas Of Changsha

Aquatic plant is an important element of the waterscape,and it plays important roles in the landscaping and water purification.In recent years,the quality requirements concerning the living environment for urban residents improved continuously accompanying the development of socioeconomic.However,the constructed waterscape in the residential areas always ignore the ecological factors and management treatments.Therefore,eutrophication becomes a common phenomenon for the waterscape.The structure of water bodies and the aquatic plants in the residential water in Changsha were investigated here.Comparative experiments were further conducted on the purification effects of the Lythrum salicaria,Acorus tatarinowii,Calla palustris and Nymphaea tetragona for water bodies of waterscape.1.Thirty residential water bodies in Changsha were investigated,and results showed that 87%of the water bodies did not achieve the national water quality standard of entertainment landscape.The eutrophication phenomenon was serious due to the hard bottom and bulkhead,and the lack of aquatic plants or just with single plant species.2.Four commonly applied aquatic plants(i.e.Lythrum salicaria,Acorus tatarinowii,Calla palustris and Nymphaea tetragona) were selected and planted to do the comparative purification experiments.The results showed that 75%,93.3%, 98.2%and 85.27%of the total phosphorus(TP) were removed within five days by loosestrife,Lythrum salicaria,Acorus tatarinowii,Calla palustris and Nymphaea tetragona,respectively.Fifteen days after the experiment began,99.2%,98.18%, 98.96%and 97.76%of the total nitrogen(TN) were removed by loosestrife,Lythrum salicaria,Acorus tatarinowii,Calla palustris and Nymphaea tetragona,respectively. Both the removal rate of chemical oxygen demand(COD) and biochemical oxygen demand(BOD₅) by Acorus tatarinowii＞Nymphaea tetragona＞Calla palustris＞Lythrum salicaria.The concentration of dissolved oxygen(DO) showed that the water bodies with Nymphaea tetragona＞Lythrum salicaria＞Acorus tatarinowii＞Calla palustris after 15 days in the experiments,and the DO in the areas with Nymphaea tetragona and Lythrum achieved the water quality standard of entertainment landscape.The pH value(ranged from 6.5 to 8.5) measured up the water quality standard of entertainment landscape. 3.This study raise appropriate conditions for the aquatic plants in aspects of the structure of bulkhead and bottom,and also bring forward a reconstruct scheme for the hard bulkhead and bottom.The results of the investigation and experiments suggest that we should pay attention to application of aquatic plants.Attention also should be paid to do the collocation of the stick out plants,float plants and submerged plants; strengthen with seasonal plants.As the Science and Educational Village waterscape of Hunan Agricultural University for an example,this study conducted water body reconstruction and allocate the aquatic plants.