Origins of nutrient salt in eutropic lakes and its control

Analyzed are the main origins of nutrient salt in eutropic lakes, including the area-source pollution induced by runoff from farms, livestock cultivation, and aqui-culture in river basins and the inner-source pollution induced by the re-suspension of liquid nutrient salt discharged from bed sediment of eutropic lakes to surface water. Then, multiple measures for control of area-source pollution are reviewed, and an introduction is given to the bottom sludge dredge method for remediation of inner-source pollution, and some ecologic measures for pollution remediation, including the restoration of higher aquatic vegetation, development of purification areas of aquatic plants, and construction of artificial wetlands. It is pointed out that the control of the nutrient salt should combine with the local natural condition and the degree of lake eutrophication, and that multiple measures should be taken to restore the structure and functions of the ecological system of eutropic lakes progressively and further to solve the problems of eutrophication.