The process, spatial and temporal distributions and mitigation strategies of the eutrophication of Lake Chaohu (1984-2013)

Abstract

通过文献调研,分析巢湖富营养化的历程及其与合肥市社会、经济与人口发展的关系,同时利用遥感解译和野外调查监测方法分析2012和2013年巢湖主要富营养化指标及蓝藻水华的空间分布特征,并进一步探讨各个阶段湖泊治理措施对巢湖富营养化过程的影响.研究发现:近30年间,1984-1994年是巢湖水质的主要恶化阶段,在1990s中期巢湖的富营养化达到了近30年的峰值,这主要是经济快速发展、污染治理投入有限所致;1995-2007年,巢湖的水质逐步改善,恢复到1980s中期略高的水平,这得益于“九五”和“十五”期间的大量投入,对污、废水进行处理,限制了污染物直接入湖;但是2008年以来,巢湖的水质改善效果并不明显,富营养化维持在较高水平波动,这可能是因为合肥市经济快速发展背景下,原有的污、废水处理后入湖的减排方式已经不能进一步有效削减巢湖的污染负荷.巢湖富营养化在空间分布上呈现西高东低的渐变趋势,这主要是由西部主要入湖河流污染所致.通过对比2012和2013年的空间分布数据发现,2013年主要入湖污染河流河口水质相对2012年均有所好转,其中十五里河河口的好转比南淝河河口明显.综合长期及全湖富营养化水平的变化分析,现阶段巢湖富营养化的治理亟需改变经济发展模式,调整产业结构,实施污废水尾水提标改造、畜禽养殖污染控制和面源污染控制等控源工程,以进一步降低巢湖的富营养化程度.;In the present study, we analyzed the eutrophication process in Lake Chaohu and its correlation with socioeconomic and population development in Hefei city. We also investigated the spatial and temporal distribution characteristics of total nitrogen, total phosphorus, ammonia nitrogen, permanganate index and cyanobacterial blooms in 2012 and 2013 in Lake Chaohu. The results showed that the water quality of Lake Chaohu started to deteriorate in 1984, and down to the worst in 1994 due to the increasing pollution and lacking of capital investment. During the period of 1995-2007, the water quality was getting better because of the limitation of direct waste water and sewage draining into the lake. After year 2008, the water quality did not show significant improvement and maintained a high level of eutrophication. In terms of spatial distributions, eutrophication in Lake Chaohu presented obviously different patterns: eutrophication level gradually degrades from the west to the east, which attributes to the source of pollution from the primary three rivers(Nanfei River, Shiwuli River and Pai River) in the west. The results from investigation also showed that the pollution from these rivers was less in 2013 than that in 2012, and the reduction in Shiwuli River was more apparent than that in Nanfei River. However, the reduction of pollution in the whole lake was not significant. Our findings suggest that in order to further reduce pollution, it is necessary to change economic development pattern and industrial structures and execute targeted pollution source control.