The density of the pollutants in the toxic slick in the Songhua River in northeast China has dropped sharply, the country's new environmental chief said on Saturday.

Zhou Shengxian, newly appointed minister of the State Environmental Protection Administration (SEPA), said that, besides the reduction in the concentration of benzene and other chemicals, work to combat the pollutants in the river would enter a new phase.

The density will be further diluted by the time the slick reaches Tongjiang, where the Songhua meets the Heilong River (called Amur in Russia) which forms the border between China and Russia, Zhou said.

The slick was still about 200 kilometers from Tongjiang last night.

The current density already meets the drinking water standard in Russia, environmental experts said.

The immediate priority was still to ensure the safety of the drinking water for residents of Jiamusi. The leading edge of the slick arrived in Huachuan County of Jiamusi yesterday.

"From now on, we will switch our working focus to appraise the impact of the pollutants on the ecosystem," China Central Television quoted Zhou as saying.

A chemical plant blast caused the slick on November 13 in Jilin, Jilin Province, in the upper reaches of the Songhua. About 100 tons of benzene and other chemicals spilled into the river, which disrupted the normal water supply of cities downstream and affected the normal life of millions of residents.

Although Jiamusi has a population of more than 2 million, the city was little affected by the slick because it relies on underground water as its main water source.

Also, a four-member team from the United Nations Environment Program arrived in Jiamusi on Saturday and joined with experts from China and Russia yesterday at the water sampling station.

By 8 AM on Saturday, the density of nitrobenzene at the Jiamusi Checking Station was 0.173 milligrams per litre and later fell to 0.162 milligrams per litre. By 8 AM yesterday, the density at the same place was 0.074 milligrams per litre.

China's Ministry of Science and Technology had already granted its first batch of 25 million yuan (US$3.08 million) for six research projects on how to deal with the water pollution, including the benzene problem, in the Songhua River.

(China Daily December 12, 2005)