Researchers extracted samples at nine sites along the Ergun, Heilongjiang, Wusuli and Suifen rivers and Xingkai Lake, and have finished lab analysis based on each country's standards, sources with the State Environment Protection Administration (SEPA), said.

The Chinese and Russian sides have gathered nearly 3,000 figures respectively this year on 40 indexes on chemical oxygen demand (COD), contents of heavy metals, pesticides, and riverbed mud to determine water quality.

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

The plan requires both sides to operate the testing program for five years from 2007. The first such test was carried out in June this year.

It was reported that water quality in three rivers - Heilongjiang, Wusuli and Songhua rivers has improved compared to the same period last year.

The Chinese government launched an 13.3 billion yuan ($1.8 billion) water pollution prevention plan along the Songhua River in 2006 and relevant departments have conducted intense inspection on pollution outlets along the river.

Source: China Daily