SWAN Village-to-Village Messaging System: Environmental Geochemistry of Mercury Mines Iin Alaska

Environmental Geochemistry of Mercury Mines Iin Alaska

Posted by Margaret on 3/24/2008, 3:56 pm
12.46.50.194

http://pubs.usgs.gov/fs/fs-0072-94/

ENVIRONMENTAL GEOCHEMISTRY OF
MERCURY MINES IN ALASKA
The U.S. Geological Survey (USGS), in cooperation with the U.S. Bureau of Mines, U.S. Fish and Wildlife Service, and Calista Corporation (an Alaska native corporation), is investigating potential environmental contamination around naturally occurring, mercury-rich mineral deposits in Alaska. Mercury deposits are scattered over a wide region in southwestern Alaska covering several thousand square kilometers. Cinnabar (mercury sulfide) is the most common mercury-rich ore mineral in the deposits, but liquid mercury is found at some localities. Several of the mercury deposits have been mined, but most of the deposits are small and have not been developed. None of the mercury mines in Alaska are currently operating due to economic factors. Mercury is used in the manufacturing of electrical instruments, fungicides, pharmaceuticals, munitions, paper production, and in the extraction of gold in mining.

ENVIRONMENTAL CONCERNS
Mercury is a heavy metal that has no known metabolic purpose and is toxic to living organisms. In humans, mercury adversely affects the central nervous system. Mercury can be converted from inorganic compounds such as cinnabar to organic forms such as methylmercury that is easily absorbed by organisms. Thus, mercury deposits and mines in Alaska are a potential hazard to residents and wildlife because drainage from these deposits enters streams and rivers that are part of local ecosystems.

The primary sources of mercury are naturally occurring mineral deposits, rocks, and volcanic eruptions, as well as man-made industrial sources, such as factory effluents and incinerations. Southwestern Alaska has no major sources of industrial mercury; however, mineral deposits in the area are of concern because mercury is highly concentrated around the deposits.

The USGS has measured the concentration of mercury in sediment, water, and fish collected from streams near some of these mercury mines and deposits and has compared these data with those from streams in unmineralized (background) areas to evaluate environmental effects of these deposits.