Black smoker

From Wikipedia, the free encyclopedia

Black smokers are a type of hydrothermal vent found on the ocean floor. The vents are formed in fields hundreds of meters wide when superheated water from below the Earth's crust comes through the ocean floor. It can also be known as a Sea Vent. The superheated water is rich in dissolved minerals from the crust, most notably sulfides, which crystallize to create a chimney-like structure around each vent. When the superheated water in the vent comes in contact with the cold ocean water, many minerals are precipitated, creating the distinctive black color. The metal sulfides that are deposited can become massive sulfide ore deposits in time.

Black smokers were first discovered in 1977 around the Galápagos Islands by the National Oceanic and Atmospheric Administration. They were observed using a small submersible vehicle called Alvin. Today, black smokers are known to exist in the Atlantic and Pacific Oceans, at an average depth of 2100 meters. The temperature of the water at the vent can reach 400 °C, but does not usually boil at the seafloor due to the high pressure it is under at that depth. The water is also extremely acidic, often having a pH value as low as 2.8 — approximately that of vinegar. Each year 1.4 × 10¹⁴ kg (370 trillion gallons) of water is passed through black smokers.

Contents 1 Black smoker ecosystem 2 See also 3 External links 4 References

[edit] Black smoker ecosystem

Although life is very sparse at these depths, black smokers are the center of entire ecosystems. Sunlight is nonexistent, so many organisms — such as archaea and extremophiles — must convert the heat, methane, and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. In turn, more complex life forms like clams and tubeworms feed on these organisms. The organisms at the base of the food chain also deposit minerals into the base of the black smoker, thus completing the life cycle.

A species of phototrophic bacterium has been found living near a black smoker off the coast of Mexico at a depth of 2500 m. No sunlight penetrates that far into the waters. Instead, the bacteria, part of the Chlorobiaceae family, use the faint glow from the black smoker for photosynthesis. This is the first organism discovered in nature to use a light other than sunlight for the photosynthetic process (Beatty, et al., 2005).

New and unusual species are constantly being discovered in the neighborhood of black smokers: for instance, the Pompeii worm in the 1980s, and, in 2001, during an expedition to Indian Ocean's Kairei hydrothermal vent field, an armor-plated gastropod. The latter uses iron sulfides (pyrite and greigite) for the structure of its dermal sclerites (hardened body parts), instead of calcium carbonate. The extreme pressure of 2500 m of water (approximately 25 megapascals or 246.73 atmosphere) is thought to play a role in stabilizing iron sulfide for biological purposes. This armor plating probably serves as a defense against the venomous radula (teeth) of predatory snails, co-existing in the same community. This snail, which is unique in its kind, has not yet been named to date.

[edit] See also

• Cold seep
• Hydrothermal vent
• Alvin submersible
• Lost City

[edit] External links

• Ocean Explorer (www.oceanexplorer.noaa.gov) - Public outreach site for explorations sponsored by the Office of Ocean Exploration.
• NOAA, Ocean Explorer Gallery, Submarine Ring of Fire 2006 Gallery, Submarine Ring of Fire 2004 Gallery - A rich collection of images, video, audio and podcast.
• NOAA, Ocean Explorer YouTube Channel
• Submarine Ring of Fire, Mariana Arc - Explore the volcanoes of the Mariana Arc, Submarine Ring of Fire.
• Hydrothermal Vent Systems Information from the Deep Ocean Exploration Institute, Woods Hole Oceanographic Institution
• How to Build a Hydrothermal Vent Chimney

[edit] References

cs:Černý kuřák

de:Black Smoker et:Must tossutaja it:Black smoker ja:ブラックスモーカー nl:Black smoker ru:Гидротермальные источники срединно-океанических хребтов sk:Čierny fajčiar fi:Musta savuttaja