Study On The Adaptability Of Plants And Purification Ability Of Water Quality On Wetland-ecological Island In River Management

At present, there are some shortcomings in technique of artificial floating island used in urban river management, such as secondary pollution, difficult management, affect landscape and leisure, and ecological function. So, to explore novel ecological restoration technology for urban river has important theoretical and practical significance.Wetland ecological island, combined with the characteristics of both artificial wetland and ecological island technology, creates new ecological restoration technology applied in urban river water environment. This paper through pilot in water ecological research and testing base and rivers demonstrating engineering, by comparison of different plants adaptability, purification potential and effect of water purification in traditional ecological island and wetland-ecological island, analysis of the suitable plant-ecological island combination; comparison of plants over-winter situation, adaptability and nitrogen and phosphorus accumulation in 2 types of wetland ecological island, studying on suitable for the growth of plants in different ecological islands and suitable plants for growth ecological island type. The conclusions are as followings.1. Test, analysis of the adaptability of plants and plant purification potential, accumulation of wetland-ecological islands plants on growth and phosphorus was higher than that in conventional ecological island; Iris sibirica adaptability and purification potential was higher than that of Phragmites communis. Analysis of plant of water quality purifying effect, ecological island with plants pollution removal rate were higher than the control group without plants; in addition to the NO3--N removal, the purification effect of wetland-ecological islands of polluted water is higher than that of the conventional type ecological island, the removal rate of TN is the lowest, the highest removal rate of nitrate nitrogen. Phragmites communis and Iris sibirica compared, in addition to NO3--N removal, purification effect of Iris sibirica is higher than that of Phragmites communis.2. In the urban river, Iris sibirica and Iris pseudacorus can be evergreen in winter in Suzhou area. Germination period of Typha orientalis around March, Pontederia cordata in the mid to late 3 to April generally. Germination time is as follows: Typha orientalis >Pontederia cordata > Scirpus tabernaemontani. Germination rate of plants was Pontederia cordata > Scirpus tabernaemontani > Typha orientalis. In the period from January 2014- October 2014, the water quality improved. Potassium permanganate index decreased by 39.02%, TP concentration decreased by 44%, TN and NH3-N were decreased 55.70%, 67.2%, COD concentration and BOD concentration changed little.3. A type of ecological islands was more conducive to 3 kinds of plants’ heights and root numbers increased, plants growth and nitrogen and phosphorus accumulation, improving the ability of removing nitrogen and phosphorus in the wetland system. The total biomass and underground biomass of Iris pseudacorus, Iris sibirica, Pontederia cordata in A island is 1.214, 1.951, 1.750 times and 1.869, 2.266, 1.472 times of B island. The optimal scheme for plant adaptability and purification potential is: Pontederia cordata >Iris sibirica > Iris pseudacorus > Scirpus tabernaemontani.4. Before and after rainfall of the urban river, ecological island internal concentrations higher than the external ecological island. After rainfall, the content of COD and BOD5 increased more violent, the concentration of TP decreased, TN, NH3-N concentration changed little. Wetland ecological island on the removal of pollutants play a role in the urban river. Wetland ecological island on Purification and ecological effect of landscape river played a role, status and the urban river sluggish stodgy, not only improved the water purification and river repair effect, but also added the effect of landscape in the limited space. Iris sibirica and Iris pseudacorus can be evergreen winter in the Suzhou area, suitable for urban river management in winter and landscape effect is better.