Statistics provided by the Bayangang monitoring post said the density of nitrobenzene in the river is 0.3590 milligrams per litre, 20.12 times above the standard.

But compared with the peak, which was 25.47 times above standard, it showed that the pollution belt was leaving the area toward Tonghe County, said Zhang Lijun, vice director of China State Environmental Protection Administration (SEPA)

Meanwhile, the Mulan monitoring post in the city of Jiamusi reported nitrobenzene density about 0.017 milligram per litre above the standard at 12:00 a.m. Tuesday.

Experts from Heilongjiang provincial environmental protection bureau said that the pollution belt will arrive at the city on Saturday.

The officials from SEPA and Heilongjiang provincial government have already arrived at the Mulan post to organize the monitoring and polluted water disposal measures.

Apart from timely monitoring and testing, the government at all levels in Heilongjiang are taking emergency measures to guarantee the water supply.

The government of Yilan County, which is located at the lower reaches of the Songhua River, asked all the residents of its Dalianhe Township to store water for five to seven days, for fear the water supply may be cut off when the pollution belt passes by.

The county government has also taken emergency measures to ensure water supply of 3,500 tons every day to the township, where more than two thirds of the residents take drinking water from the Songhua River.

The water pollution was caused by a chemical plant blast on November 13 in neighboring Jilin Province, resulting in serious leakage of poisonous substances into the Songhua River.

Harbin, capital of Heilongjiang with Songhua River as its main water supply source, enforced a four-day suspension of water supply since November 24.

Currently, the water supply in Harbin has resumed and the water quality of all its water supply stations have reached the national standard on Tuesday.