Beijing Water Authority said on Thursday minor algae blooms have
been found in some water areas in the capital, and warned the city
faces risks of algae outbreaks.
Zhang Shiqing, director of the authority's rivers and lakes
department, said about 100 square meters of algae blooms have been
found in water areas of Chaoyang district in eastern Beijing and
the Summer Palace in the capital's northwest.
The algae blooms were triggered by poor ventilation and slow
water flows, he said, adding that the algae had been cleared.
Nine other water areas, including Houhai, Yuyuantan lake and the
Bayihu lake, are also prone to algae blooms, he added.
Zhang said the conditions were right for algae blooms. "There
has been scant rainfall this year to dilute the water, some of
which was already polluted by garbage. The summer heat is also
helpful."
Statistics with the authority show Beijing is home to 118.39
kilometers of rivers with 8.66 million square meters of water
area.
He said the department has cleared 27,000 cubic meters of
garbage and silts from water areas. It also introduced water
lilies, snails and shellfish to boost biological diversity, and
catalysts and chlorine to purify water.
Eighteen monitoring stations had been set up, he added.
Algae blooms in rivers and lakes were unlikely to affect water
supplies in the city, as the major water sources were underground
water and reservoirs in suburban Miyun and Huairou districts, Zhang
said.
Algae blooms are usually formed in water that is rich in
nutrients, when the number of algal cells increase to a point where
they discolor the water, form scum, produce unpleasant tastes and
odors, and seriously reduce water quality.
In the last two months, blue-green algae outbreaks have been
reported in Taihu Lake, Chaohu Lake, the southwestern Dianchi Lake,
and a reservoir that provides water to Changchun, capital of
northeast China's Jilin Province, endangering domestic water
supplies.
(Xinhua News Agency July 20, 2007)