Huge algae outbreaks again pose a threat to drinking water supply from Taihu
and Chaohu, two of China's major freshwater lakes.
Satellite pictures showed blue-green algae covering about a third of both
lakes in the country's densely populated east, according to the National
Satellite Meteorological Center.
2,400-sq-km Taihu Lake, the country's third largest freshwater lake on the
border of Jiangsu and Zhejiang provinces, about 800 sq km is covered with the
fast-growing and foul-smelling green plant.
A large outbreak a few weeks ago contaminated the lake and resulted in the
shutdown of tap water to about 2 million residents in Wuxi, Jiangsu Province.
But the latest outbreak has not affected drinking water safety because the
algae is found far from the water intake points, said Li Jianqiu, a spokesman
with Wuxi utilities bureau.
The nearby city of Changzhou, which uses the Yangtze River as its water
source, has also not been affected, said a government spokesperson.
In the 780-sq-km Chaohu Lake in Anhui, China's fifth largest freshwater lake,
280 sq km is carpeted by algae.
Last week, the satellite monitoring system showed that patches of algae had
spread over 40 sq km in the lake, a source of drinking water for some 260,000
Zhang Zhiyuan, a spokesman for the Anhui provincial environmental protection
bureau, said the situation was being closely watched.
File photo shows that workers remove
algae in a Beijing lake.[AFP]
He said the water from the Yangtze River will be diverted to the lake to
improve water quality.
Zhang Bangguo, an expert with the Chaohu bureau of environmental protection,
said excessive nutrients in the lake, including nitrogen and phosphate from
fertilizers, industrial runoff and untreated sewage, as well as high
temperatures, have provided good conditions for the algae bloom.
"A large algae bloom can break out any time given suitable sunlight and
temperature," Zhang said.
"Once the conditions for algae growth are ripe, it's very difficult to
effectively control it in the short term," Li Yucheng, a professor at Anhui
University's School of Life Sciences, was quoted as saying yesterday by the
"Relief measures can only reduce the harm from an outbreak to a minimum but
cannot solve the problem totally."
(China Daily 06/18/2007 page1)