Discovery.Com
Mercury used
in hydraulic mining in California's mountains more than a century
ago is showing up in catfish and bass in two northern Sierra Nevada
watersheds.
California
officials issued warnings about eating fish caught in the Bear
River and Yuba River following a report released on Tuesday by
the U.S. Geological Survey (USGS). The group's research revealed
that the region's fish were contaminated with high levels of liquid
elemental mercury, commonly known as quicksilver.
Mercury was
used in hydraulic mining to separate gold from ore, enabling it
to be extracted later. Charlie Alpers, the study's chief scientist,
estimated that three to eight million pounds of mercury had been
dumped into the region during the Gold Rush in the process.
Although twelve
bodies of water in California have health advisories related to
mercury in fish, there are no such warnings for the state's historic
gold country.
Jason May,
a USGS biologist, warned of the more insidious presence of methylmercury,
which becomes more concentrated as it moves up the food chain.
Predatory fish such as brown trout and bass tend to have the highest
concentrations of methylmercury.
Mercuric poisoning
can cause developmental problems, nerve damage, motor skill deficiencies
and behavior disorders. Infants and unborn babies whose nervous
systems are still developing are particularly susceptible.
Hydraulic
mining, also known as placer mining, was a quick and expedient
way to remove gold ore from mountainsides using high-pressure
hoses. The technique left huge portions of land eaten away, and
the subsequent erosion has had a vast environmental impact on
the region.
|
