Hydrothermal Vents Fuel Marine Organisms with Iron

On dry land, animals get their daily iron supplies from plants or read meat, but in the deep ocean things are a bit more difficult. Yet organisms living here need iron just as much as their more complex counterparts on the surface. A new study shows that hydrothermal vents are providing the chemical.

These natural chimneys, which connect the planetary mantle with the crust, and allow for the venting of dangerous and hot gases, apparently release vast amounts of pyrite nanoparticles. Dubbed fool's gold, pyrite is a form of iron sulfide that tiny plants and bacteria on the ocean floor use instead of iron.

Until now, experts couldn't establish where there organisms were getting their supplies of the chemical from. The discovery was made even more difficult by the fact that the pyrite nanoparticles are more than 1,000 times smaller than the diameter of a human hair.

Due to their reduced size, they simply float around in the ocean after they are released in the water, rather than simply falling down to the bottom. In the new study, experts with the University of Delaware demonstrate that vast amounts of pyrite are released from these vents.

Details of the new work appear in the latest issue of the top journal Nature Geoscience. The team says that the discovery is very important, as it finally sheds more light on the intricate chemical cycles underlying the way our oceans function.

“These particles have long residence times in the ocean and can travel long distances from their sources, forming a potentially important food source for life in the deep sea,” explains researcher Barbara Ransom.

The expert holds an appointment as the program director of the Division of Ocean Sciences (DOS), at the US National Science Foundation (NSF). The new work was funded by DOS and the NSF Experimental Program to Stimulate Competitive Research (EPSCOR).

“As pyrite travels from the vents to the ocean interior and toward the surface ocean, it oxidizes gradually to release iron, which becomes available in areas where iron is depleted so that organisms can assimilate it, then grow,” explains George Luther.

“It's an ongoing iron supplement for the ocean--much as multivitamins are for humans,” the University of Delaware scientist adds. Pyrite was dubbed fool's gold because it has a bras-yellow-like color, which made many prospectors believe it was gold.

The fact that hydrothermal vents are allowing bacteria and small plants to survive in the oceans was unknown until now. This discovery adds to a string of conclusions other studies drew about this amazing structures.