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Blue-green algae outbreaks likely to occur again
By Li Jing (China Daily)
Updated: 2008-04-21 10:10
Outbreaks of blue-green algae, which sparked last year's water pollution crisis in Wuxi in Jiangsu province, may hit the Taihu Lake again this summer, say some scientists and top environmental officials. "Large-scale outbreaks of blue-green algae are very likely to occur as temperatures rise," says Zhang Lijun, vice-minister of Environmental Protection (MEP), who led a one-week inspection trip in Jiangsu and Zhejiang provinces in early April. In late March, signs of blue-green algae blooms were spotted in southern part of the Taihu Lake earlier than previous years. Blue-green algae occur naturally as part of the food chain and is found in the rivers and lakes all over the world. But scientists say blue-green algae can become overly abundant in warm, shallow, undisturbed surface water that receives a lot of sunlight and an overabundance of nutrients, such as nitrogen and phosphorus. Pollution can greatly boost the outbreaks. Last May, in the lakeside city of Wuxi, a sudden overgrowth of the blue-green algae polluted the intake area for drinking water, which resulted in the suspension of the fresh water supply to half of the 2.3 million city's residents for a week. Located in the highly developed and densely populated Yangtze River Delta, Taihu Lake, China's third largest freshwater lake has become increasingly polluted in the recent years. "During the last two decades, the overall water quality of Taihu Lake dropped from the national standard Grade II to worse than Grade V, or unfit for human contact," says Jin Xiangcan, a leading expert on water environment at Chinese Research Academy of Environmental Science, who just finished a research project on algae control at Taihu Lake. Jin says the excess nutrients in the Taihu Lake were a result of continuous sewage and industrial pollution that provide favorable conditions for algae's growth. There are no short-term solutions to clear the nitrogen and phosphorus compounds from the lake, says Jin. He adds that the blue-green algae infestation would last at least three to five years, even if all the sources immediately stopped discharging waste into the lake, says Jin. This is probably the reason that vice-minister Zhang has described the combat to clear Taihu Lake a "a protracted battle." He urged local authorities closely monitor the blue-green algae to ensure that the outbreaks would not again threaten the drinking water supply. Lacking effective measurements to prevent more blue-green algae blooms, fishing them out was necessary to try to minimize the damage. But last year, the algae started to decay before it was first removed from the lake and the water soon became foul smelling. (For more biz stories, please visit Industries)
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