Environmental authorities of China and Russia finished taking samples from border rivers for quality tests on Wednesday in the first national-level joint operation since 2005.

Environmental experts from both sides took water samples from the Heilongjiang, Wusuli and Suifen rivers and Xingkai Lake.

They would analyze the samples separately and compare the results, said the Heilongjiang Provincial Bureau of Environmental Protection.

Experts will examine chemical oxygen demand, contents of heavy metals, benzene, and pesticides, riverbed mud, and other indices to determine water quality.

It is the first joint operation since China and Russia signed the Joint Monitoring Plan on Border Rivers in 2006, after an accident at a Chinese chemicals plant sent nitrobenzene and other chemicals into the Songhua River that flows into the Heilongjiang River in 2005.

The contamination forced Harbin, capital of Heilongjiang Province in China's northeast, to temporarily stop water supplies to 3.8 million people.

The plan requires both sides to operate the testing program for five years from 2007. In the first year, environmental departments will carry out two tests. The second is expected to be held in August.

Heilongjiang Province and Russia's Khabarovsk have been conducting border river monitoring since 2002 in an effort to ensure water quality and improve environmental protection.

(Xinhua News Agency June 29, 2007)