A study was conducted last year of 30 of the country's major rivers that carry processed water to the sea. Their combined run-off volume accounted for 81.5 percent of the nation's total.

The results showed a significant increase over the previous year in the levels of pollutants discharged via the Yangtze River, Pearl River, Yellow River, Minjiang River and several others.

The volume of major pollutants such as chemical oxygen demand (COD), oil, ammonium, phosphate, arsenic and heavy metals (copper, lead, zinc, cadmium and mercury) was about 13.82 million tons.

Of the total, COD accounted for 11.93 million tons (86.3 percent), nutritive salts 1.73 million tons (12.5 percent), oil 117,000 tons, heavy metals 30,000 tons and arsenic 6,000 tons.

(China Daily May 11, 2007)