Pollution From Algae May 'Kill' DianchiBlue-green algae - which has threatened Dianchi Lake, the biggest lake in Southwest China's Yunnan Province, for three decades - will soon be out of control again, provincial government sources said on Thursday.The provincial government has spent more than 3 billion yuan (US$361 million) during the past decade trying to bring the algae under control. However, Yunnan Vice-Governor Chen Xunru conceded that the best solution to the problem is still unclear. Blue-green algae, a kind of water plant, grows easily in polluted water with a high concentration of nitrogen and phosphorous and with temperatures around 18 degree centigrade. Too much blue-green algae will remove oxygen from the water killing fish and other aquatic life, and can turn Dianchi into a "dead"lake. Blue-green algae has been threatening Dianchi Lake since 1970s. Last year, blue-green algae covered 20 square kilometres of the lake, one-fifteenth of the lake's total area. Since 1993, the provincial government has tried to curb the growth of blue-green algae. Four sewage treatment plants were built near the lake. They are able to treat a total of 365,000 tons of waste water each day. A government-led campaign last year spurred 249 of the 253 factories along the lake to stop dumping their industrial sewage into the lake. The government also spent 250 million yuan (US$30 million) to dredge 4.2 million cubic metres of mud. However, these efforts fell short. The network to collect sewage is incomplete, and more than 80 per cent of domestic sewage with fertilizers and pesticides still flow into the lake through 16 rivers, experts said. |
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