STUDY OF NITROGEN AND PHOSPHORUS FLOW IN WATER, AQUATIC PLANTS AND SEDIMENT

Using aquatic plants to control nitrogen (N) and phosphorus (P) loads and restore eutrophic lakes has been put into practice since the 1980s.However, existing studies can hardly illustrate the law of N&P flow in water, aquatic plants and sediment during the growth of plants.In this study, three typical aquatic plants, two emerged plants and one submerged plant from Lake Gehu, China, were chosen to study the rule of N&P flow.The N&P contents and some related parameters in the water, sediment and plant samples were measured and the correlations between them were analyzed.The results show that the flow of N&P is generally controlled by the growth of plants, and N can flow directly between plants and sediment while P transfer is more significant in water and sediment.In emerged plants, 70-75% total nitrogen (TN) and over 50% total phosphorus (TP) is concentrated in leaves at early and medium stages of growth, and at the decline stage N&P transfer to roots.Results also show that reaping plants around August and purifying sediment after plants decay can make nutrient removal efficiency.