More efforts are being put into mitigating cadmium pollution in a river in Guangxi Zhuang autonomous region that threatens the water safety of downstream cities, local authorities said Monday.

Environmental protection workers have been dumping neutralizers, made from dissolved aluminum chloride, at five locations on the Longjiang River to dissolve the contamination.

Cleanup work will be conducted at two more locations, six km downstream of Luodong hydropower station, where the pollutants were concentrated Sunday night, and another further downstream, somewhere near Sancha hydropower station, said Qin Bin, deputy secretary of the Hechi city committee of the Communist Party of China.

"It is a critical time right now as the downstream drinking water safety is in jeopardy, so we will take every measure possible and optimize our strategies to bring down cadmium concentration levels," Hechi mayor He Xinxing added.

There is a pollution belt stretching for 100 km on the Longjiang River in which the cadmium concentration is over five times higher than the official limit of 0.005 milligrams per liter, while some pollutants have flowed close to a major drinking water source for downstream city Liujiang, according to the emergency headquarters handling the incident.

The Longjiang River is a tributary upstream of the Liujiang River which runs through Liujiang city.

Tests conducted at 8 a.m. Monday show that the cadmium concentration of the water within a 16-km radius of the Hexi water plant of Liujiang was just slightly under the restricted level, according to the headquarters.

Despite the daunting perspective, officials are still hopeful.

"There is 100,000 tonnes of groundwater available in Liujiang, so we are confident that we can guarantee the drinking water supply for people's everyday use," said an official with the headquarters.

The contamination was first detected on Jan. 15 and was traced to a plant belonging to Guangxi Jinhe Mining Co. Ltd.

In Hechi, the pollution killed many fish and prompted panic buying of bottled water over the past week.

Cadmium is a carcinogenic chemical mostly found in industrial effluents.

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.