Thursday, 26 September 2013
oceanic iron cloud spreads for more than 1,000 k
The oceanic iron cloud spreads for more than 1,000 kilometers (621 miles) across the Atlantic from west of Angola, Africa, to northeast of Rio de Janeiro, Brazil. The iron-rich waters flow 1,500 to 3,500 meters (4,921 – 11,482 feet) beneath the surface of the ocean. The complete extent and shape of the iron plume remains to be discovered.
“We had never seen anything like it,” said Mak Saito, Woods Hole Oceanographic Institute scientist and lead author of the study, in a press release. “We were sort of shocked—there’s this huge bull’s-eye right in the middle of the South Atlantic Ocean. We didn’t quite know what to do with it, because it went contrary to a lot of our expectations.”
Cracks in the Earth crust, or hydrothermal vents, on the ocean floor released the iron. However, the type of vent came as a surprise to the Woods Hole Oceanographic Institute and University of Liverpool oceanographers who discovered it.
A long ridge splits the Atlantic Ocean as geological forces gradually force the ocean wider. The slow-spreading Atlantic ridge was thought to produce less iron and other chemicals than vents in regions with speedier splits, like the ridge in the eastern Pacific.
“This study and other studies like it are going to force the scientific community to reevaluate how much iron is really being contributed by hydrothermal vents and to increase those estimates, and that has implications for not only iron geochemistry but a number of other disciplines as well,” said Saito.
The Atlantic Ocean iron plume may provide a smorgasbord for oceanic phytoplankton, the tiny, plant-like organisms that form the base of many marine food webs.
Those phytoplankton provide food for fish and whales. The plankton also suck in large amounts of carbon dioxide. When the plankton die they can carry that carbon with them to bottom of the ocean.