Investigation and Evaluation of Rreservoir Eutrophication in Chongqing

The 36 reservoirs were investigated in Chongqing, concentration of chlorophyll a is 1.5952.3 mg/m~3;TP is 0.0020.598 mg/L;TN is 0.525.94 mg/L;SD is 0.483.2 m; COD_(Mn) is 0.759.3 mg/L. There are significant positive correlation between COD_(Mn),TN and chlorophyll-a, SD was significantly negative with chlorophyll-a, correlation between TP and chlorophyll-a was weak, the relation of chlorophyll-a, total phosphorus and transparency are showed by using regression method, corrected Carlson Trofic State Index are used to evaluate the eutrophication degree of 35 reservoirs, 27 reservoir were eutropher and 8 reservoir were mesotropher. Eutrophication condition of the reservoir in main city and west of Chongqing were more serious than which in Three gorges reservoir area. Nutrient output of 3 huge reservoirs were calculated and were contrasted with 67 sewage limbers, the amount of total nitrogen output only the 3 reservoirs were exceeded to 67 sewage and output of total phosphorus were about 16 percent occupied sewage.