Chinese Mines Pollute Tibet's Rivers, Streams

More primitive efforts at resource extraction have also damaged Tibet’s environment, said Lafitte, pointing to “the ongoing pollution legacy of literally hundreds of surface gold extraction operations in almost every streambed in Tibet.”

This was the result of an “unregulated boom” in the 1980s and 1990s when poor Chinese peasants came to Tibet from Sichuan and other nearby provinces because they were no longer able to make a living on their own land, Lafitte said.

The poorest used mercury and cyanide to extract the gold, Lafitte said.
http://www.rfa.org/english/news/tibet/mines-05062013154914.html