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Hydrothermal Vents

Hydrothermal vents


Hydrothermal vents are hot springs located on the ocean floor. The vents spew out water heated by magma, molten rock from below the earth's crust. Water temperatures of higher than 660°F. have been recorded at some vents.

Water flowing from vents contains minerals such as iron, copper , and zinc. The minerals fall like rain and settle on the ocean floor. Over time, the mineral deposits build up and form a chimney around the vent.

The first hydrothermal vents were discovered in 1977 by scientists aboard the submersible Alvin. The scientists found the vents near the Gal ápagos Islands in the eastern Pacific Ocean. Other vents were discovered in the Pacific, Atlantic, and Indian oceans.

In 2000, scientists discovered a field of hydrothermal vents in the Atlantic Ocean. The area called the "Lost City" contained 180-feet tall chimneys. These were the largest known chimneys.

Hydrothermal vents are located at ocean depths of 8,200 to 10,000 feet. The area near a hydrothermal vent is home to unique animals. They exist without sunlight and live in mineral-levels that would poison animals living on land. These unique animals include 10-foot-long tube worms, 1-foot-long clams, and shrimp.

[Liz Swain ]

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Hydrothermal Vents

Hydrothermal Vents

A hydrothermal vent is a geyser that is located on the floor of the sea. The first such vent was discovered in 1977 on the floor of the Pacific Ocean. Since then, vents have been discovered at a variety of locations in the Pacific Ocean, Atlantic Ocean, Indian Ocean, and even in the water under the polar ice cap.

The vents tend to be located deep in the ocean. For example, in the Atlantic Ocean, some 7,000 ft (2,134 m) beneath the surface, hydrothermal vents are associated with underwater mountain chain called the Mid-Ocean Ridge. This ridge is geologically active with an upwelling of hot magma and volcanic activity. The tectonic plate movements cause faulting and the seawater that enters the cracks is superheated by the molten magma. The superheated water and steam and spews out through hydrothermal vents.

Some vents, known as black smokers, spew out a black-colored mixture of iron and sulfide. White smokers eject a whitish mix of barium, calcium, and silicon.

This eruption through the hydrothermal vents is continuous, in contrast with the sporadic eruptions of surface geysers. The material that emerges from hydrothermal vents is extremely hot (up to 750°F [398.89°C]) and is very rich in minerals such as sulfur. The minerals can precipitate out of solution to form chimneys. The construction of a chimney can occur quickly. Growth of 30 ft (9 m) in 18 months is not unusual. The tallest of these chimneys that has been measured was the height of a 15 story building.

A vibrant community of bacteria, tubeworms that are unique to this environment, and other creatures exists around hydrothermal vents. The entire ecosystem is possible because of the activity of the bacteria. The work of Holger Jannasch (1927-1998) at the Woods Hole Oceanographic Institution, established that these bacteria utilize sulfur to produce energy in a process of chemosynthesis that does not require direct light from the sun. The chemical energy is then available for use by the other life forms, which consume the bacteria, or consume the organisms that rely directly on the bacteria for nourishment. For example, the tubeworms have no means with which to take in or process nutrients. Their existence relies entirely on the bacteria that live in their tissues.

Research lead by scientists at Woods Hole is progressing to catalogue the life at hydrothermal vents, particularly the bacterial varieties, and to genetically compare the bacteria from different locations around the globe. An expedition planned for 2007 will for the first time study the hydrothermal vents in the Arctic Ocean.

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