What is the reason for this large-scale outbreak of cyanobacteria in Taihu Lake?

The blue-green algae broke out in Taihu Lake, and the tap water quality in our city suddenly became abnormal, which has never been encountered before. After careful research and scientific analysis by the expert group and relevant departments in recent days, the reasons have been determined:

Climate influence is an important reason for the large-scale outbreak of cyanobacteria in Taihu Lake this year. According to the climate impact assessment conducted by meteorologists, due to global warming, the cold air south of the Yangtze River was located in the north in the winter of 2007 (65438+ last February and 1 and this February), and its intensity was weak. In 2007, there was an obvious warm winter weather in Wuxi, which caused the cyanobacteria not to freeze to death in a large area last year, and accumulated conditions for the outbreak of cyanobacteria in May this year. Especially in the spring of this year, the temperature continued to be abnormally high, the precipitation was less, and the climate was abnormal, which led to the appearance of many meteorological indicators for seasonal change 25-30 days in advance and the early summer. These climatic factors have become an important reason for the sudden abnormality of water quality in our city due to the large-scale outbreak of cyanobacteria in Taihu Lake ahead of schedule this year.

A large number of cyanobacteria died, fermented and stinked to form a sewage mass, and suddenly invaded the water intake of Gong Hu water source, which was the direct cause of the sudden abnormality of tap water quality. After a detailed investigation and analysis of the sudden change of water quality in the water source area, the expert group agreed that under the specific wind direction and hydraulic conditions this year, a large number of cyanobacteria broke out in Taihu Lake and gathered in the reeds and nearby waters on the northern shore of Gong Hu Lake. Due to the changes of environmental factors such as temperature and climate, cyanobacteria died and sank to the bottom of the water. During the decomposition of cyanobacteria, a lot of dissolved oxygen in the water body is consumed, which leads to serious pollution and black odor, forming a large area of sewage mass (about 3 square kilometers) and suddenly invading the water source of Gong Hu Lake to get it.

In addition, Taihu Lake in Wuxi is located in the northwest of Taihu Lake. As a whole, it is a semi-closed lake bay, surrounded by the sea on three sides, and the fluidity of water is poor. Due to the southeast wind all the year round in Taihu Lake basin, the overall water pollution in Taihu Lake often drifts to Wuxi waters with the wind and accumulates, which leads to the increasing environmental bearing pressure and the deteriorating water quality in Wuxi waters of Taihu Lake, which has become a geographical factor for the outbreak of cyanobacteria and the sudden change of water quality in Taihu Lake.