HEZHOU, Guangxi, July 9 (Xinhua) -- Police in south China believe they have located the source of toxic waste water that was discharged into a local river.
The source of the contaminants is believed to be the Huiwei Ore-Processing Company, which is situated on the upper reaches of the Hejiang River in the city of Hezhou in south China's Guangxi Zhuang Autonomous Region, according to initial police investigation.
Police found that the plant, which passed an environmental assessment in February 2008, had been illegally producing indium, a toxic rare metal used in alloys, electronics and electroplating.
Li Weizhang, director of the Public Security Bureau of Hezhou, said the company's indium production line was illegally installed. All processing materials were purchased from elsewhere and contained highly toxic thallium.
Senior engineer Wang Zhenxing, a member of an investigation panel from the South China Environmental Protection Supervision Center under the Ministry of Environmental Protection, said the company is suspected of changing its production process without authorization and discharging toxic waste water directly into the ground.
"When it rains, the toxic waste water flows into the nearby Haodong River, which then feeds into the Hejiang River," said Wang.
The company's head, a man surnamed Gong, has been placed under police custody.
A dam is being built on the Haodong River to prevent contaminated water from reaching the Hejiang River which runs across the autonomous region.
Once the dam is built, the contaminated water will be trapped, allowing local authorities to use a coagulating agent to reduce the concentration of pollutants in the water.
Contamination on the Hemianshi Reservoir, which is located on the Hejiang River, is less serious, so no coagulating agents are needed, experts said.
The pollution was first detected on Saturday, when authorities in Fengkai County in neighboring Guangdong Province said a local river had been tainted by upstream pollution.
Dead fish have been seen floating on the Hejiang River since July 1. Officials have warned local tap water plants and residents living on the lower reaches of the river to avoid drinking water or consuming products derived from the river.
Pollutants discharged from upstream will eventually flow into the Pearl River, a major water source in south China.
Local environmental authorities said Monday afternoon that rivers in the autonomous region have been vulnerable to environmental pollution due to the heavy presence of industrial activity, such as mining.
In January 2012, industrial effluents containing cadmium that were discharged by a mining company polluted the Longjiang River in Guangxi. Since then, local authorities have created a campaign to weed out mining companies that fail to comply with environmental standards.
During the campaign, 79 companies in Hezhou were found to have compliance issues, said Yang Zhongxiong, deputy director of the Bureau of Environmental Protection of Hezhou.
The city once thrived on mining activity, but when local mining resources were nearly exhausted in 2002, many major mining companies went bankrupt.
However, some small-scale miners tucked into the mountainous region have continued mining with insufficient oversight by local environmental authorities, posing the risk of toxic leaks in rivers that converge with downstream water sources in south China, according to Lei Shaohua, director of the Land Resources Bureau of Hezhou.
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