Hydrothermal vents provide a fascinating view into a part of our planet that was only vaguely imagined a quarter-century ago and is still not well understood today. Beyond their intrinsic interest, vents
- play an important role regulating the temperature and chemical balance of the oceans;
- help us investigate the origin of life on our planet and elsewhere in our solar system;
- hold promise for solving medical and industrial problems on the earth's surface;
- are a potential source of recoverable resources; and
- generate controversy about their future exploration and exploitation.
Geochemists theorize that all the water in the world's oceans is recycled through hydrothermal vents once every 6 - 8 million years in a process called hydrothermal circulation.
This image shows how water seeps into cracks in the ocean's crust, is heated by magma, and eventually reemerges through a hydrothermal vent. It loses magnesium (Mg) and sulfide (SO4) and gains metals such as copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), and sulfur (S) on its journey.
Oceanographer Peter Rona of Rutgers estimates that the amount of water entering fissures each year is equal to the annual flow of the Amazon River.
Hydrothermal circulation has a significant impact on the temperature and chemical balance of the oceans. It removes magnesium and sulfate from seawater, and adds calcium, potassium, gases such as hydrogen sulfide and methane, and trace metals such as iron and manganese. Until the discovery of hydrothermal vents, scientists had believed that the chemical balance of the oceans was determined primarily by run-off from the continents. Now run-off and hydrothermal infusion are thought to be equally important.
At one time, scientists believed volcanic and hydrothermal vents might be a site of "cold fusion." Today, however, according to Professor Gary McMurtry, a geochemist at the University of Hawaii, "The tritium associated with magmatic waters probably comes from fallout sources, while the helium-3 associated with volcanoes is largely from primordial sources deep within the earth's mantle."
Vent fluids containing microbial cells as well as gases rise from the ocean floor for tens to hundreds of meters to eventually become diluted plumes spread horizontally by the currents. Scientists have detected effects of hydrothermal vents 1000 kilometers (621 miles) and farther away from their source on the Juan de Fuca Ridge off the coast of Oregon.
Megaplumes can form quickly, within a matter of hours, and are often associated with volcanic activity and a shifting of the earth's tectonic plates. A vent that opened in February, 1996 produced a plume of hot water, minerals and microbes that was 9.66 km (6 mi.) wide.
Life Found on Other Planets? -->
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