The Assessment of the Eutrophication Status and Analysis on the Main Controlling Factor of Erlongshan Reservoir

Based on the practical monitoring data of Erlongshan Reservoir, the paper estimated the status of the eutrophication by the comprehensive trophic state index method. The results indicated that the Erlongshan Reservoir was between mesotropher and Light eutropher with the index from 46.5903 to 57.3904. The degree of eutrophication was in the order of high flow period>average and low period. According to the analysis on the variation law of mass concentration ratio of TN to TP and available nitrogen to resolvable orthophosphate, determining the limiting factor for eutrophication was phosphorus in Erlongshan Reservoir.