So much for the grand plan by enthusiasts for dusting the ocean with iron to produce a high plankton content. It turns out that by itself it produces a toxic red tide. Now the schemes touted for promoting CO2 sequestration were at best fanciful and this shows that they were a long way from even been thought out. Yet it is not a total loss.
The need for Oceanic fertilization is obvious. Throwing sacks of fertilizer over board is a bone stupid way to do it, particularly since the improved biomass is likely to benefit fish stocks thousands of miles away. Yet there is something there. It tells us that the potential for fertilization in terms of an increased global fishery is actually huge.
Such a fishery would be able to support a global population way larger than 100 billion.
The better way to provide fertilization is to establish vertical elevator tubes that reach well into the deep. The tubes them selves would be perhaps a hundred meters wide and formed with a concrete composite so it may be cast in place and slowly sunk with oil filled bladders to provide neutral buoyancy. Such a structure could be cable stayed to keep in place with anchor weights.
Once built, the natural gradient in temperature and pressure will drive bottom water from the bottom to the surface, emulating the upwelling activity along natural sea mounts. Thus we gain a fast moving column of water shooting out through the top of the tube. Once established a slow turbine can be placed in the throat to slow the flow rate enough to allow a gentle escapement and draw of power.
It is conceivable that such a device which is built while avoiding any difficult deep sea engineering would be also self financing and last for centuries. Some care would have to be provided to manage fouling but if the structure is as large as I am envisaging, this will never be a significant problem except in terms of buoyancy management. Of course it should be possible to bring the entire structure to the surface as needed to run defouling operations and may be needed.
The by product of such a device would be a massive flow of nutrient rich bottom water onto the surface to be carried down current stimulating massive plankton growth and the resultant sea life
My point is that this is technology well inside our ability and it can be placed strategically throughout the oceans in tiers to take advantage of particular currents. Thus hundreds of such power stations could be placed at the head of a major current and the whole downstream would become a huge fishery comparable to the Grand Banks .
Iron Stimulates Blooms Of Toxin-Producing Algae In Open Ocean
by Staff Writers
Silver noted that blooms of Pseudo-nitschia must occur naturally in the open ocean as a result of iron deposited by dust storms, volcanic eruptions, and other airborne sources.
A team of marine scientists has found that toxin-producing algae once thought to be limited to coastal waters are also common in the open ocean, where the addition of iron from natural or artificial sources can stimulate rapid growth of the harmful algae.
The new findings, reported this week in the Proceedings of the National Academy
Blooms of diatoms in the genus Pseudo-nitschia, which produce a neurotoxin called domoic acid, are a regular occurrence in coastal waters.
During large blooms, the algal toxin enters the food chain, forcing the closure of some fisheries (such as shellfish and sardines) and poisoning marine mammals and birds that feed on contaminated fish. But until now, blooms of these algae in the open ocean have attracted little attention from researchers.
"Normally, Pseudo-nitschia cells are sparse in the open ocean, so they don't have much effect. But these species are incredibly responsive to iron, often becoming dominant in algal blooms that result from iron fertilization. Any iron input might cause a bloom of the cells that make the toxin," said Mary Silver, professor emerita of ocean sciences at the University of California, Santa Cruz, and lead author of the new study.
Because both natural and artificial additions of iron to ocean waters cause phytoplankton (single-celled algae) to grow vigorously, and because phytoplankton take up carbon dioxide as they grow, iron fertilization of the oceans has been suggested as way to reduce atmospheric concentrations of carbon dioxide and thereby combat global warming.
"This work definitely reveals a wrinkle in those plans," said coauthor Kenneth Coale, director of Moss Landing Marine Laboratories.
"It is much easier to break an ecosystem than it is to fix one. In light of these findings, we should redouble our efforts to reduce carbon emissions, the primary culprit for ocean ecosystem damage worldwide."
In 2007, Silver accompanied Ken Bruland, professor of ocean sciences at UCSC, on a research cruise to study iron chemistry in the Gulf of Alaska . She saw Pseudo-nitschia cells often in samples collected at sea, and analysis of the samples back in the lab showed the presence of the domoic acid toxin.
Those findings prompted her to team up with Coale to analyze old samples collected during iron-enrichment experiments conducted in 1995 and 2002. Coale was the principal investigator or chief scientist for these studies.
"We thought the toxin would have broken down, but it was still there," Silver said.
In addition to samples from the two iron-enrichment experiments, the researchers analyzed samples from three natural populations in the North Pacific. The results showed that oceanic waters throughout the Pacific contain Pseudo-nitschia populations associated with the domoic acid neurotoxin.
Silver noted that blooms of Pseudo-nitschia must occur naturally in the open ocean as a result of iron deposited by dust storms, volcanic eruptions, and other airborne sources. "It is a natural phenomenon and likely has been for millions of years," she said.
"But those are sporadic occurrences. To do iron enrichment on a large scale could be dangerous because, if it causes blooms of Pseudo-nitschia, the toxin might get into the food chain, as it does in the coastal zone."
In addition to Silver, Coale, and Bruland, the coauthors of the PNAS paper include Sibel Bargu and Ana Garcia at Louisiana State University; Susan Coale and Kathryn Roberts at UC Santa Cruz; and Claudia Benitez-Nelson and Emily Sekula-Wood at the University of South Carolina. This research was funded by the National Science Foundation, U.S.Department of Energy, and U.S.
No comments:
Post a Comment