A cofferdam of Dushan flood control works is breached to discharge water of Taihu lake in Wuxi, east China's Jiangsu Province, June 1, 2007. Breaches were made on some cofferdams of China's third-largest Taihu lake to sluice water polluted by an blue-green algae bloom. Water authorities had also diverted the Yangtze River to dilute the lake water. (Xinhua/Cheng Binghong)
WUXI,
Jiangsu, June 2 (Xinhua) -- A team of water pollution experts have succeeded in
dispelling the unpleasant odor from the water supply of east China's Wuxi city,
but authorities say the water is still not safe to drink.
Domestic supplies would resume soon, but the city's 2
million residents should continue to drink bottled water rather than risk the
tap water, which was polluted by an algae bloom in the main water source.
Wuxi Mayor Mao Xiaoping said a team led by Professor
Zhang Xiaojian, of Beijing's Tsinghua University, succeeded in dispelling the
stench produced by the blue-green algae at Taihu Lake with potassium
permanganate, an oxidant.
Workers also added active carbon powder at treatment
plants.
"It took Professor Zhang and his team 17 hours of
trials to reach the right formula to eliminate the unpleasant odor," said Mao.
Residents have been told to run their taps to clean
the pipes.
Wu Jianxuan, vice mayor of Wuxi, announced Friday
that domestic tap water rates would be reduced by half in June in compensation.
Both officials refused to give an exact date for the
resumption of a drinkable water supply.
Blue-green algae is an aquatic plant that occurs
naturally in rivers, lakes, damp soil, tree trunks, hot springs and snow.
"Bloom" is the common term used to describe an increase in the number of algal
cells to a point where they discolor the water, form scum, produce unpleasant
tastes and odors, affect shellfish and fish populations or otherwise create a
nuisance and seriously reduce water quality.
Experts blame three factors -- high temperatures,
less rainfall and low water levels, and abnormally high concentrations of
phosphorus and nitrogen in the lake water -- for the outbreak of blue-green
algae bloom in the Taihu Lake.
Since last Tuesday, many residents of Wuxi, have
turned on their taps to receive yellowish, stinking water.
The pollution led to a panic buying of bottled water
and bread.
Local authorities are allocating more bottled water
from neighboring cities of Suzhou, Changzhou, Nanjing and Shanghai.
The city's pricing bureau has banned water price
hikes. Vendors who deliberately drive up prices face fines of up to 300,000 yuan
(39,200 U.S. dollars).
The local meteorological observatory recorded an
average temperature in the Taihu Lake region of 17.1 degrees Celsius in the
first five months, 0.7 degrees higher than previous years and the highest since
1955.
Rainmakers fired 39 rockets containing silver iodide
from eight sites around Taihu Lake on Thursday afternoon and Friday morning,
inducing a rainfall of more than 20 mm.
Meanwhile, the city government of Wuxi, 128 km
northwest of Shanghai, has opened a number of deep wells, which had been sealed
off for fear of excessive extraction, for use during the emergency.
Water authorities have also diverted the Yangtze
River to dilute the lake water, according to the Taihu Valley Administration
under the Ministry of Water Resources.
China has seen string of water pollution accidents,
with more than 140 cases since 2005 when drinking water to millions of people in
the northeastern city of Harbin was stopped after a chemical spill contaminated
the Songhua River.
Among the top 10 environmental pollution cases listed
by the State Environmental Protection Administration (SEPA) last year, seven
were connected with water pollution, including four that directly led to unsafe
drinking water.
Major supermarket chains have transported emergent supply of bottled water from neighboring cities to the eastern Chinese city of Wuxi in Jiangsu Province to relieve the severe water shortage. Local citizens are buying the bottled water on May 31, 2007. (Xinhua Photo) Photo Gallery>>>
WUXI, Jiangsu, May 31 (Xinhua) -- China has stepped up the diversion of the Yangtze River to dilute water polluted by blue-green algae in a lake that provides drinking water for millions of people in the eastern Chinese city of Wuxi, Jiangsu Province.
Water from the nation's longest river is flowing into Taihu lake at a rate of 150 cubic meters per second, up from the earlier 127 cubic meters per second, and the lake has received a total of 190 million cubic meters of Yangtze water since May 11, said the Taihu Valley Administration under the Water Resources Ministry on Thursday. Full story
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