(Xinhua)
Updated: 2007-09-04 16:11

WUHAN - A Chinese scientist believes he has found a potential solution to China's growing problem of blue-green algae outbreaks in the country's lakes.

Yu Dan, Professor of Botany and Zoology with the College of Life Sciences at Wuhan University, said that growing more aquatic weeds could curb lake contamination.

Yu reached the conclusion after his research team succeeded in removing large swathes of algae from the Liangzi Lake, situated between the three industrial cities of Wuhan, Erzhou and Huangshi on the middle reaches of the Yangtze River, through the growth of aquatic weeds.

"Aquatic weeds and algae are the two primary kinds of lake-borne plants and are fighting against each other in the same environment," said Yu. "A good growth of aquatic weeds can absorb more nutrients such as nitrogen and phosphorus, depriving the algae and improving the quality of the lake water."

Blue-green algae grows easily in polluted water with a high concentration of nitrogen and phosphorous and a temperature of around 18 degrees Celsius. An excess of blue-green algae removes oxygen from the water, killing fish and other aquatic life.

Liangzi Lake, the second largest lake in Hubei Province, has a water area of 28,000 hectares. It fell victim to frequent algae outbreaks in the late 1980s as a result of unrestricted development of aquaculture on the lake, coupled with the emergence of a large number of industrial projects and mining businesses which directly discharged waste water into the lake, causing the ecological environment of the lake to deteriorate.

The local government has closed business ventures, dismantled 2,000 hectares of aquacultural grounds, improved the environment around the lake and introduced fishing bans to curb the lake's degradation.

In the meantime, Chinese scientists led by Professor Yu have grown 13,333 hectares of aquatic weeds in the Liangzi Lake since 1992. Aquatic weeds are now growing in 80 percent of the lake.

The efforts appear to have paid off. Local environmental protection organizations now monitor that the water in the Liangzi Lake has attained the I-category and II-category levels, which both meet drinking water standards.

The practise of planting weeds has also been implemented in Changtan Reservoir in Taizhou, East China's Zhejiang Province. The reservoir was crippled by an algae bloom from 1999 to 2001.

Yu brought water weed seeds and propagating agents to Changtan Reservoir in 2002 and grew 666 hectares of aquatic weeds. The quality of water in the lake returned to the II-category level a year later.

Yu hopes to use the weed-planting technique to reduce pollution in other major lakes in China but there are no concrete plans at present and he is quick to recognize the scale of the task ahead.

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