Part of the Pearl River that flows through the southern section of city Guangzhou was again polluted Monday by dirty and disgusting black water from an upper river branch.

The southern Guangzhou section of the Pearl River is distinctively polluted by black water on Monday, October 20, 2008. [Yangcheng Evening News]

The Yangcheng Evening News in southern Guangdong Province reported that such pollution has kept occurring over the past two years. However, there are still no convincing explanations as to how that happens and what the pollutants are despite continuous complaints and some so-called official investigations.

According to one investigation conducted by the local environmental protection bureau on Monday, the pollution, they said, was caused by dirty black silt dredged up from the river bed when a power plant discharged its waste along that upper branch river it sits by, but the extended period of pollution weakened this explanation.