Controlling of Internal Phosphorus and Nitrogen Loading in Lake Sediment by Submerged Macrophytes and Its Application

The mechanisms and effects of submerged macrophytes in controlling lake sediment nitrogen (N) and phosphorus (P) internal loading are described and analyzed. Submerged macrophytes can decrease nitrogen and phosphorus contents in the sediment and reduce nitrogen and phosphorus release through several mechanisms, such as growth and reproductive assimilation, promotion of microbial metabolism and decomposition, improvement of physical and chemical environment of sediments, and inhibition of sediment resuspension. Statistical results based on simulation and field studies show that the average N and P removed from sediment by submerged macrophyte was 1 136 and 387 mg·kg^-1·a^-1, respectively, which was positively related with the initial concentrations of pollutants in sediment. With submerged macrophyte, the inhibition rate of N and P release was reduced by 62.6% to 107.7%, and 41.2% to 253.8%, respectively, compared to no-plant area. The restoration of submerged macrophyte is an effective measure to control the internal loading, while the removal of N and P is affected by many factors. When the submerged plant recovery technique is applied, the appropriate species should be used and collocated reasonably. To achieve better control effects, restoration of submerge macrophytes should be used in combination with other measures in space and process flow.