LIUZHOU, Guangxi - Cadmium pollution in a river in south China's Guangxi Zhuang autonomous region has been controlled and no new leaks have been found following a spill from an industrial plant, local environmental authorities said Sunday.

Armed police dump bags of alkali into water to dissolve the contamination at the Nuomitan waterpower plant in Liucheng county of Liuzhou city, Guangxi Zhuang autonomous region, Jan 27, 2012. [Photo/Xinhua]

Cadmium concentrations in the Longjiang River in the city of Yizhou, where the spill occurred, have been brought within acceptable levels, said Gan Jinglin, head of the environmental protection bureau of the downstream city of Liujiang.

The contamination was first detected on January 15 and has been traced to a plant belonging to Guangxi Jinhe Mining Co, Ltd.

The cadmium pollutants are mainly concentrated near the Luodong hydropower station on the Longjiang River and still pose a threat to water safety in Liujiang, according to experts with a task force in charge of handling the incident.

"Since the pollutants were spread over a large section of the Longjiang River and are moving downstream, Liujiang is still threatened, but we have been able to secure safe drinking water for local residents," Gan said.

The cadmium concentration at the Nuomitan hydropower station, located 56 km away from the Hexi water plant in Liuzhou, was eight times higher than the official limit of 0.005 milligrams per liter as of noon on Sunday.

Water located within a 16-km radius from the Hexi water plant is considered vital for water supply safety. The Sunday morning tests showed that the cadmium concentration on a section of river located 16 km from the plant was 0.0041 milligrams per liter, just below the official limit, Gan said.

"However, the rising cadmium concentration means that the pollutants are approaching, and it is still unknown when the concentration peak will occur and how high it will be," Gan said. "We are keeping a close eye on the river's water quality."

"The Nuomitan hydropower station is a vital spot for the control of pollutants and it determines water safety in Liuzhou," said Tang Zhenguo, deputy head of Liucheng county.

The lives of fishermen along the Liujiang River have been severely affected by the cadmium pollution.

The family of Xie Shuisheng from Fengshan township, Liucheng county, lives on a boat.

"We have to drive our boat to the Rongjiang River to fetch drinking water, as we were informed a couple of days ago that the Longjiang River was polluted and the water is undrinkable," Xie said.

"We dare not to fetch water from the river before the threat is eased," Xie added.

Other fishermen are worried about the pollution's negative effects on the river's fish.

Cadmium is a carcinogenic chemical mostly used in industrial effluents.

A chemical agent designed to clump the contaminants together has been dumped into a dam on the Longjiang River to assist in clean-up efforts.

All seven of the heavy metal production plants located upstream of the river have suspended operations in order to curb potential sources of new pollution.

Jinhe Mining Co, Ltd is suspected to be one of the sources of the pollutant, as its dumping site is not up to the national standard, according to Wu Haique, director of the environmental protection bureau of the city of Hechi.

However, further investigations into other plants must be conducted as more proof is needed to ascertain the sources of the pollution, Wu said.