Mercury is an efficient magnet for gold. The early California miners routinely lined their sluices with the silvery globules to amalgamate the precious metal. Up to 10 percent of an estimated 65,000 tons of mercury extracted from the Coast Range between 1850 and 1920 was lost to streams in the Coast and Sierra mountains. Modern gold miners working suction dredges still find pockets of the Argonauts' quicksilver lodged deep in the "guts" of rivers.
| Fish advisories due to mercury contamination | |
 San Francisco Bay/Delta system | |
| Species Bass: Striped - larger than 27 inches |
Advisory No consumption: Populations at risk (1) No consumption: All consumers No consumption: Populations at risk Restricted consumption (2): All consumers |
 Santa Clara County (3), Alamitos Creek, Alamden Reservoir, Calero Reservoir, Guadalupe Creek, Guadalupe River, Guadalupe Reservoir | |
| Species All fish |
Advisory No consumption: All consumers |
 Napa County: Lake Berryessa | |
| Species All fish Bass: Largemouth, smallmouth Catfish: Channel, white Trout: Rainbow | Advisory No consumption: Populations at risk Restricted consumption: All consumers |
 Solano County: Lake Herman | |
| Species Bass: Largemouth |
Advisory Restricted consumption: All consumers |
 Lake County: Clear Lake | |
| Species All fish Bass: Largemouth Blackfish: Sacramento Catfish: Brown, bullhead, channel, white Crappie: Black |
Advisory No consumption: Populations at risk Restricted consumption: All consumers |
 San Luis Obispo County: Lake Nacimiento | |
| Species Bass: Largemouth |
Advisory No consumption: Populations at risk Restricted consumption: All consumers |
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(1) Populations at risk: Children, pregnant women and women of child-bearing age. (2) Restricted consumption: Quantity and frequency should be restricted by indicated population to no more than one meal per month. (3) All Santa Clara County locations include associated percolation ponds. | |
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Mercury in the ecosystem Mercury in aquatic environments takes on a vicious life of its own. Bacteria converts the metal into the more toxic methyl-mercury, which can be taken up by insects, the fish that eat the invertebrates and humans who eat the fish. Mercury's concentration increases at each level up the food chain in a process known as biological magnification. | |
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Health effects of mercury
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Deteriorates the nervous system|
Recovering mercury The mercury that stuck to the gold was removed and recovered by heating the amalgam. The quicksilver changed from a solid to a gas in the furnace. Upon cooling, the mecury vapor coverted to liquid for reuse. | |
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1. The amalgam of gold and mercury was placed in the furnace and heated. 2. Mercury turns to gas at a lower temperature than gold, so the vapor would be composed of mercury. 3. The mercury vapor was then cooled further down the pipe into liquid mercury. |
Sources: Tom Suchanek, a research ecologist at the University of California, Davis; Information Center for the Environment, UC Davis; California Department of Conservation Division of Mines and Geology; Teale Data Center; CALFED Program
Bee graphic: Mitchell Brooks
