A black smoker in the Atlantic Ocean

A black smoker or sea vent is a type of hydrothermal vent or underwater hot spring found on the ocean floor. They are formed in fields hundreds of meters wide when superheated water from below Earth's crust comes through the ocean floor. This water is rich in dissolved minerals from the crust, most notably sulfides. When it comes in contact with cold ocean water, many minerals precipitate, forming a black chimney-like structure around each vent. The metal sulfides that are deposited can become massive sulfide ore deposits in time.

Black smokers were discovered in 1977 on the East Pacific Rise by scientists from Scripps Institution of Oceanography. They were observed using a small submersible vehicle called Alvin. Now black smokers are known to exist in the Atlantic and Pacific Oceans, at an average depth of 2100 meters. The most northerly black smokers are a cluster of five named Loki's Castle,"Boiling Hot Water Found in Frigid Arctic Sea". livescience.com. 2008-07-24 discovered in 2008 by scientists from the University of Bergen at 73 degrees north, on the Mid-Atlantic Ridge between Greenland and Norway. These black smokers are of interest as they are in a more stable area of the Earth's crust, where tectonic forces are less and consequently fields of hydrothermal vents are less common."Scientists Break Record By Finding Northernmost Hydrothermal Vent Field". Science Daily. 2008-07-24 The world's deepest black smokers are located in the Cayman Trough, 5,000 m (3.1 miles) below the ocean's surface."World's deepest undersea vents discovered in Caribbean". BBC News. 2010-04-12

The water at a vent can reach 400 °C (752 °F), but does not usually boil at the seafloor because the water pressure at that depth exceeds the vapor pressure of the aqueous solution. 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.

Deep sea vent biogeochemical cycle diagram.

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 — convert the heat, methane, and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. 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, therefore 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 2,500 m (8,200 ft). 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 photosynthesis.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 a scaly-foot gastropod in 2001 during an expedition to the Indian Ocean's Kairei hydrothermal vent field. 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 250 atmospheres) 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 in that community.

• Van Dover CL, Humphris SE, Fornari D, Cavanaugh CM, Collier R, Goffredi SK, Hashimoto J, Lilley MD, Reysenbach AL, Shank TM, Von Damm KL, Banta A, Gallant RM, Gotz D, Green D, Hall J, Harmer TL, Hurtado LA, Johnson P, McKiness ZP, Meredith C, Olson E, Pan IL, Turnipseed M, Won Y, Young CR 3rd, Vrijenhoek RC (2001). "Biogeography and ecological setting of Indian Ocean hydrothermal vents". Science 294 (5543): 818–23. doi:10.1126/science.1064574. PMID 11557843. PMID 11557843
• Van Dover, Cindy Lee (2000). The Ecology of Deep-Sea Hydrothermal Vents. Princeton University Press. ISBN 0-691-04929-7.
• Beatty JT, Overmann J, Lince MT, Manske AK, Lang AS, Blankenship RE, Van Dover CL, Martinson TA, Plumley FG. (2005). "An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent". Proceedings of the National Academy of Sciences 102 (26): 9306–10. doi:10.1073/pnas.0503674102. PMID 15967984. PMID 15967984

• 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
• Giant black smoker retrieved from abyss - a vent chimney retrieved by an Australian CSIRO Research Vessel north of Papua New Guinea in April-May 2000.
• Ancient Black Smoker - Parys Mountain, Anglesey

ca:Xemeneia mineralitzant cs:Černý kuřák de:Schwarzer Raucher et:Must tossutaja fa:دودکش سیاه it:Fumarola nera nl:Black smoker ja:ブラックスモーカー pt:Fumarola negra ru:Гидротермальные источники срединно-океанических хребтов simple:Black smoker sk:Čierny fajčiar fi:Musta savuttaja uk:Чорні курці vi:Ống khói đen