Evaluation Of The Algae And Ecosystem Health In Nansi Lake

Nansi Lake is one of the important storage lake, and also the main water source of Shandong Province for industrial, agricultural and domestic water. It's water quality not only affects the sustainable development of Nansi Lake area, but also affects the water quality safety of the East Route South-to-North Water Transfer Project. At present, the lake eutrophication has become the major environmental problem in our country. At the same time, the algal "bloom" is an important factor, which affects the safety of water supply in lake. Therefore, it has important practical significance and value guide to analyze the algae growth factor of the East Route South-to-North Water Transfer Project and evaluate the ecosystem health of Nansi Lake for carrying out the Eastern Route Project Successfully, reducing the risk of diversion water quality, protecting the water quality safety of the water receiving region, and promoting the healthy development of the social and economic along the South-to-North Water Transfer Project.In this paper, spss13.0 software is used for analyzing the correlation between the main environment factors and chlorophyll a, algae density, based on the water temperature, total nitrogen, total phosphorus, pH, CODMn, turbidity, transparency and DO and other factors as independent variables, chlorophyll a and algae as the dependent variable. Deeply analyze the grow status of the green algae, cyanobacteria, diatoms and other phytoplankton affected by the main environmental factors.In the meantime, the ecosystem health status of Nansi Lake is evaluated in this paper, with the method as follows:Firstly, build the ecosystem health evaluate indicators system for Nansi Lake, which is come from the three parts mainly:the environmental factors indicators, the structure indicators and the system indicators (including ten sub-indicators), considering the actual situation of the Nansi Lake and the data obtainable situation when selecting evaluate indicators. Secondly, determine the ecosystem health evaluation criterion for Nansi Lake, divide the health status into five levels; Thirdly, calculate the each indicator weight of Nansi Lake by weighted average method; Finally, get the ecosystem health status from the fuzzy comprehensive evaluation method. The evaluation results:the health level of Nansi Lake is general. It is the ecosystem health level for five monitoring sites as follows:Qian baikou is in illness, Er jiba is in common illness, t Nanyang is in excellent, Da juan and Daodong's health statue is in common.