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发表于 2009-7-28 09:12:19
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Years of mineral exploitation had disastrous effects on the area's forests, groundwater and even its geology.
EPB's current director, Tian Hongchang, said a huge area between 100 and 150 meters deep underground was hollowed out in the mining process. Miners built five levels of tunnels, stacked one on top of the other and fanning out like a spider's web, beneath Wanshan's streets.
"The most serious area had seven layers of tunnels, and the narrowest area was only seven or eight meters thick, relying on only a few ore pillars for support," said Tian. "One could say that the city of Wanshan is built on an excavation hole on the verge of collapse."
But even more worrisome than the dangerous labyrinth of tunnels, Tian said, is the serious contamination of the area's environment. During its 45-year life-span, Guizhou Mercury discharged some 20.2 billion cubic meters of mercury gas, 42.6 billion cubic meters of industrial waste and 51.9 million tons of wastewater. Some of these emissions exceeded safety standards by thousands of times.
Few of these discharges were processed, leaving high levels of metallic mercury in the environment. Liu estimates at least 350 tons – equal to nearly 10 percent of the world's annual mercury emissions -- were released into the Wanshan environment.
A study by Guizhou Zunyi Medical College and other organizations the year Guizhou Mercury went bankrupt found airborne mercury levels of 0.0053 milligrams per cubic meter, 1.67 times the limit set by the government. Mercury levels in drinking water exceeded standards by more than 36 times.
Cheng Jinping, an associate professor at Shanghai Jiaotong University's School of Environment and Engineering, told Caijing that most of the mine's mercury emissions were in the form of inorganic mercury, for which the human body's absorption rate is relatively low. However, when mixed with water, relatively harmless inorganic mercury acidifies and becomes deadly methyl mercury.
In this way, methyl mercury accumulated in the area's rice paddies and vegetable plots, poisoning food. |
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