http://www.nsf.gov/news/news_
May 8, 2011
Similar to humans, the bacteria and tiny plants living in the ocean need iron for energy and growth. But their situation is quite different from ours--for one, they can't turn to natural iron sources like leafy greens or red meat for a pick-me-up.
So, from where does their iron come?
New research results published in the current issue of the journal Nature Geoscience point to a source on the seafloor: minute particles of pyrite, or fool's gold, from hydrothermal vents at the bottom of the ocean.
Scientists already knew the vents' cloudy plumes, which spew forth from the earth's interior, include pyrite particles, but thought they were solids that settled back on the ocean bottom.
Now, scientists at the University of Delaware and other institutions have shown the vents emit a significant amount of microscopic pyrite particles that have a diameter 1,000 times smaller than that of a human hair.
Because the nanoparticles are so small, they are dispersed into the ocean rather than falling to the sea floor.
Barbara Ransom, program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research, called the discovery "very exciting."
"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," she said.
The project also received support from another NSF program, the Experimental Program to Stimulate Competitive Research, or EPSCOR.
The mineral pyrite, or iron pyrite, has a metallic luster and brass-yellow color that led to its nickname: fool's gold. In fact, pyrite is sometimes found in association with small quantities of gold.
Scientist George Luther of the University of Delaware explained the importance of the lengthy amount of time pyrite exists suspended in its current form in the sea, also known as its residence time.
Pyrite, which consists of iron and sulfur as iron disulfide, does not rapidly react with oxygen in seawater to form oxidized iron, or "rust," allowing it to stay intact and move throughout the ocean better than other forms of iron.
"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," Luther said.
"It's an ongoing iron supplement for the ocean--much as multivitamins are for humans."
Publish PostBlooming algae can produce nasty odours.
The Canning River could get a bit smelly if an algae bloom continues to worsen between Riverton and Cannington.
The Swan River Trust is monitoring elevated levels of single-cell algae, gymnodinium, which can bloom to reach high numbers.
Trust principal scientist Kerry Trayler said while this particular species is not known to be harmful to humans or produce toxins; it can strip the water of oxygen and produce foul odours.
Dr Trayler said fish and other animals in the river could be affected if oxygen levels continue to drop in the areas between Riverton and Bacon Street, Cannington, however tidal movements could push the bloom significantly downstream.
Fish that are affected by low oxygen levels will be slow-moving and sluggish.
The Department of Health has maintained its long-standing advice to the community not to eat mussels, cockles or oysters from the Swan and Canning Rivers.
The state has closed areas of the Nauset Marsh system between Orleans and Eastham on Cape Cod to shellfishing because of concerns about toxic "red tide".
Among the areas included are Nauset Harbor, Town Cove, and Mill Pond in Orleans and Salt Pond in Eastham.
Digging, harvesting or collecting and/ attempting to dig, harvest or collect shellfish and the possession of shellfish, including carnivorous snails, from the defined areas is prohibited.
The state said experts from the Woods Hole Oceanographic Institute have seen increasing levels of the toxic plankton in the marsh system.
