A barge sank on the Chao Phraya River in the Phra Nakhon Si Ayutthaya province of Thailand.   The barge had a cargo of 2,300 tons of sugar which was release into the river.   The sugar quickly dissolves and causes the oxygen levels in the river to drop.   The Pollution Control Department states the dissolved oxygen level in the river is at 1.9 mg/litre which is much lower than the normal levels of 3 to 6 mg/litre.   Also, the barge rests in a narrow section of the river which has stopped river traffic.  Clean up operations are being conducted and hopes that rainfall and water released by a dam upriver will restore the water quality.  Authorities are demanding the barge to be removed quickly as possible.