基于滇池水生态系统演替的富营养化控制策略

自20世纪80年代以来,滇池开始爆发大规模蓝藻水华。滇池治理一直以提高水质为主要目标,以污染控制为主要手段。近10年来,滇池水质虽呈现明显好转趋势,但长期实施的污染控制工程并未有效抑制蓝藻水华爆发。通过浅析滇池富营养化特征,分析当前治理思路和方法中存在的不足,并结合生态系统稳态转换理论和一些国内外富营养湖泊治理经验,认为滇池具备在较高营养盐浓度(V类水质)下恢复清水草型生态系统的可能性,提出滇池治理可以适当降低对水质的要求,在污染物控制的基础上辅以生态修复措施的治理思路,最终实现滇池生态系统由浊水-藻型向清水-草型演替。

Study on eutrophication control strategy based on the succession of water ecosystem in the Dianchi Lake

With rapid increase in local population and of consequences of massive municipal and industrial sewage discharged into the lake,pollution of the Dianchi Lake has been deteriorated since the 1980s.The lake is in a status of heavy eutrophication,accompanied with cyanobacteria bloom.During the past decade,many pollution control projects have been implemented in the Dianchi Lake to eliminate external nutrient loads and improve the water quality.However,after the vast capital has been injected,the nutrient level still stays at an unacceptable level,although external pollutant load has been gradually reduced to a bit lower level.On the other hand,the characteristics of shallow lake dominating the water quality of the lake is insensitive to the reduction of external nutrient loads.In this paper,we analyze the evolution process of eutrophication in the Dianchi Lake and elaborate how human activities damaged the ecosystem in the lakeside zone and accelerated the eutrophication process.The existing pollution control projects,which cost too much,can hardly meet the requirements of nutrients control.According to the stable states theory and the simulation of the relationship between nutrition degree and algae outbreak in the Dianchi Lake,we believe that there exists a probability to recover the ecosystem in Dianchi Lake from turbid state to clear state,from phytoplankton dominated state to plants dominated state.Thus,we suggest that the projects of ecosystem recovery in the Dianchi Lake should be implemented by combining pollutant control with ecological restoration.