Mercury contamination in California to last 10,000 years

Toxic remnants of gold rush will seep into San Francisco area waterways for millennia

By Jessica Shugart, 11:43 AM October 28, 2013

California’s gold rush ended more than a century ago, but the contamination it caused will last thousands of years, a new analysis shows.

Some hydraulic gold mining processes use the toxic metal mercury to separate gold from gravel. In the mid-1800s, gold mining released more than a cubic kilometer of mercury-laden sediments into Northern California’s Sierra Nevada foothills. The sediments fanned out and inundated rivers that flow into the San Francisco Bay. Researchers estimate that 90 percen...

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