Research On Fate Of Phosphorus And Balance Of Phosphorus Total Amount In The Course Of Purifying Eutrophic Water By Water Hyacinth

How to control the lake eutrophication becomes the focus and difficulty in the field of water pollution at present. Large scale confined growth of water hyacinth has been widely used in Dianchi Lake, Taihu Lake for water improvement and nutrients reduction successfully. However, for the fate and balance of phosphorus and other related issues are unclear:① is the plant absorption of phosporus by water hyacinth leading to the ecological restoration of the system?② are the different life forms of plants absorbing the same phosphorus sources? The phosphorus is mainly from sediment or water? In response to these problems, researches were conducted to provide data to assess the application of water hyacinth to promote ecological restoration techniques. The main findings are as follows:1. Floating plants and emergent plants could effectively reduce the total phosphorus, total dissolved phosphorus, soluble reactive phosphorus concentrations in water. Water hyacinth, water lettuce and cattails had a higher removal rate than control. Submerge plant Hydrilla removed less total phosphorus, total dissolved phosphorus, soluble reactive phosphorus in water than the control group. For total phosphorus removal capacity:water hyacinth>lettuce>cattail>blank>hydrilla; for total dissolved phosphorus removal capacity: water hyacinth>lettuce>cattail>blank>hydrilla; for soluble reactive phosphorus removal capacity:lettuce>water hyacinth>cattail>blank>hydrilla. Past 80 days of experiment, the water hyacinth, water lettuce and cattail removed 95.0%,94.3% and 92.0% of total phosphorus. Water hyacinth removed up to 90% of total phosphorus from the eutrophic water after 30 days, which show strong absorption ability of water hyacinth to total phosphorus in eutrophic water.2. In the process of restoration of eutrophic water systems using water hyacinth, plants absorbed phosphorus being the most important way to reduce the phosphorus in the system, accounting for over 80% of the total phosphorus removed from the system; 10% of total phosphorus removed system contributed to the adsorption and root shedding from water hyacinth. Root shedding along is less than 2% of the total phosphorus.In the control group, sediment released phosphorus into the water body due to very low concentration of phosphorus in water.3. Sediment played an important role in the nutrient balance. In this experiment. About 32.0% of water hyacinth assimilated phosphorus came from water and 70.6% of that came from sediment, Purification of phosphorus from eutrophic water absorption in water and sediment of water hyacinth; Lettuce absorbed phosphorus mainly from eutrophic water; Cattail biomass increased very little, in reducing the water total phosphorus concentration and phosphorus content, increase slightly, from the table view, the main source of water for the absorption of phosphorus element; Submerged plant hydrilla absorbed phosphorus mainly from sediment and absorbed less phosphorus than control, but reduced phosphorus content in sediment; The control group without plant growth, phosphorus content is lower, the release of phosphorus from water.In summary, the absorption and accumulation of phosphorus in water hyacinth, water lettuce, cattails and hydrilla could effectively improve the water quality. Water hyacinth could absorbe up to 80% of phosphorus from the water. Under the condition of this experiment, water hyacinth purification of eutrophic water phosphorus from water and sediment; water lettuce of eutrophic water absorption of phosphorus from water; cattail purification of eutrophic water absorption of phosphorus from the water; Sediment is the main source of phosphorus supply for hydrilla.