Nitrobenzene pollution from a chemical plant explosion has continued to drop in the Songhua River in the northeast, the environmental protection agency said yesterday.

The environmental watchdog agency reported the nitrobenzene density has continued to drop at Jiamusi, 244 kilometers upstream from Tongjiang city, where the Songhua River joins the Heilongjiang River and then flows into Russia.

The report said the concentration of nitrobenzene at Jiamusi at 8pm on Monday was 0.0077 milligrams per liter. Meanwhile, the chemical was measured at 0.0222 and 0.0687 mg/l at 8am and 4pm on Sunday at Donghe, which is 130km upstream from Tongjiang.

But the chemical density at Donghe is growing, according to the latest monitoring figures.

The nitrobenzene density was measured at 0.0527 mg/l at 2am yesterday at Huachuan, 202 kilometers upstream from Tongjiang.

The nitrobenzene density has been falling as the slick flows downstream due to evaporation and settling.