Succession of nine plateau lakes and regulation of ecological safety in Yunnan Province

The Nine plateau lakes are those lakes whose areas are larger than 30km2 in Yunnan province.These lakes are Dianchi Lake,Erhai Lake,Fuxian Lake,Chenghai Lake,Lugu Lake,Qilu Lake,Xingyun Lake,Yangzonghai Lake,and Yilong Lake.The nine plateau lakes are important for economic development and for ecological security.However,all lakes are facing different environmental issues such as eutrophication and water quality degradation.Different strategies should be proposed according to the various conditions of the lakes.Three types of prevention,control and treatment strategies were proposed based on the succession process,the ecology stages,the economic and social development,the eutrophication stages,the water qualities,and the dominant ecological functions.

Nitrogen forms and pollution load of Dianchi Lake inflow river runoff in rainy season

With the control of point source pollution in Dianchi Lake basin, and the expansion of Kunming city, non-point source pollution has become the main source pollution of urban water environment and Dianchi Lake. To reveal the nitrogen pollution characteristics in watershed, this research selected key monitoring points and sections at Baoxiang river basin in rainy season which is the peak transported time of non-point source pollution, the nitrogen and hydrological indicators are monitored systematically. The different forms of nitrogen are analyzed, the pollution load of nitrogen are calculated and studied at cardinal sections; combined with the literature data, we compared the water nitrogen characteristics of Dianchi basin and Taihu basin, the main results are as follows:(1) In summer, water nitrogen form of Baoxiang river in the Caohe area is dominated by nitrate nitrogen, while in other areas it is dominated by ammonia nitrogen which is accounted for 31%-50% of total nitrogen;(2) The water pollution loads of Baoxiang river tended to increase from upstream to downstream, from June to August the total nitrogen pollution mainly comes from urban areas and the pollution load is 166.408 t;(3) In Dianchi Lake watershed and Taihu Lake watershed nitrogen concentration of inflow river is higher than that of the lake, nitrate nitrogen concentration between inflow river and lake shows a little difference, while ammonia nitrogen concentration of inflow river is higher than that of the lake. The results can provide the theoretical basis for nonpoint source pollution control and urban water environment planning and improvement in Dianchi Lake Basin.